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Tuatara aims to stimulate and widen interest in the natural science in New Zealand, by publishing articles which (a), review recent advances of broad interest; or (b), give clear, illustrated, and readily understood keys to the identification of New Zealand plants and animals; or (c), relate New Zealand biological problems to a broader Pacific or Southern Hemisphere context. Authors are asked to explain any special terminology required by their topic. Address for contributions: Editor of Tuatara, c/o Victoria University of Wellington, Box 196, Wellington, New Zealand. Enquiries about subscriptions should be sent to: Business Manager of Tuatara, c/o Victoria University of Wellington, Box 196, Wellington, New Zealand.
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In Both Pre-Human Times, and since the arrival of man about 1,000 years ago, many New Zealand land birds have become endangered or extinct. Some controversy has developed about the importance of man, and his manifold influences on the environment in causing these changes (Myers, 1923, Greenway, 1958, Williams, 1962, 1964, Fleming, 1962a, b). One aspect of this problem, which needs study, is ‘why did certain species become extinct or endangered while others persist?’ We need to know whether extinctions have occurred randomly, or whether the extinct species have something in common which may indicate possible reasons for the extinctions. If some such common characteristic can be found, then I think we have begun to understand the extinctions.
Data on which analyses were based were derived primarily from Oliver (1955), Fleming (1962a, b), Fleming et al (1953) and Williams (1962). Although the validity of some of the taxa used by these workers may be questioned, especially concerning the
Williams (1962) listed the birds in New Zealand which are extinct, or which, in his opinion, are in serious danger of extinction; I have adopted Williams' listing, and dealt with the following orders:— Dinornitbiformes, Apterygiformes, Podicipitiformes, Anseriformes, Psittaciformes, Galliformes, Gruiformes, Strigiformes, Columbiformes and Passeriformes. I also followed Williams in examining separately, the status of the species in the North, South, Stewart and Chatham Islands. To some extent, at least, each island constitutes a separate faunal area within the New Zealand region, since there are endemic species or subspecies in each and extinctions have occurred independently in each.
Oliver (1955) showed that most if not all, of the extinct land birds have been found as subfossil remains, or in moa excavations, and Fleming (1962a) reached a similar conclusion. If these extinct species are regarded as having survived until even the last two thousand years, it seems reasonable to regard their extinctions as contemporary in the geological time scale. On this basis I am taking the extinctions recorded by Oliver, Williams and Fleming, as having occurred in a contemporaneous bird fauna.
In analysis, I have listed separately the bird faunas of the North, South, Stewart and Chatham Islands. From this list, for each area, I determined the level at which each species is endemic to the New Zealand region, i.e. whether it belongs to an endemic order, family, genus, species, subspecies, or to a nonendemic subspecies; and I also noted whether each species has been recorded as either extinct or endangered, or is not so recorded. Then within the list for each island, I determined the percentage of species, endemic at each of the above taxonomic levels, which is in the extinct or endangered category (table 1).
Fleming (1962a) estimated approximate arrival times in New Zealand of the ancestors of the endemic orders, families, genera etc, as follows:— endemic orders in the late Cretaceous, more than 70 million years ago; families 25 to 70 million years ago; genera one to 25 million years ago; species 15,000 to one million years ago; subspecies 1,000 to 15,000 years ago; nonendemic subspecies in the last 1,000 years, some since the European settlement of New Zealand, about 120 years ago. I have taken the midpoints of these time intervals, such that the times for each are, say, 85 million years (order), 47½ million years (family), 12 million years (genus), 507,000 years (species), 8,000 years (subspecies) and 500 years (nonendémic subspecies). In fig 1, these levels were inserted along a log scale, such that the proximity of the taxa to each other is in accord with their time of arrival in the New Zealand region, as projected by Fleming (1962a).
The New Zealand land bird fauna is small, comprising only about 97 species. Fleming (1962a) postulated that since the late Cretaceous (at which time he considered that the moas and kiwis — orders Dinornithiformes and Apterygiformes — were in New Zealand), the fauna has been built up by immigration. The geographic relationships of the fauna were analysed by Falla (1953). The migratory and sea birds have extremely diverse relationships with southern temperate, Antarctic, Indo-Pacific, Holarctic and other, widespread species. The more recently arrived land birds are almost exclusively Australian, but the relationships of the older, endemic orders and families of birds are presently unclear. How the first, flightless birds arrived in New Zealand is a perplexing
The number of invasions which has contributed to the present New Zealand bird fauna can be estimated by determining the number of phylogenetic stocks that has evolved in the New Zealand region — the number of species in each genus and the distribution patterns of the genera and species, e.g. nonendemic species and nonendemic genera with only one species in New Zealand have clearly dispersed to New Zealand and have their closest relatives elsewhere; nonendemic genera with several endemic or nonendemic species could have dispersed one or more times. Fleming (1962a) considered that the moas and kiwis may represent two invasions, and each of the endemic families of passerines seems likely to represent a separate, single invasion. With increasing endemicity and age, these estimations become increasingly difficult and less reliable, but the figures do provide some insight into the manner in which the fauna has been derived. In table 2 I have listed estimates of the maximum and minimum number of invasions which could have built the fauna. Compared with the total number of species (97), the number of invasions (44-59) seems to be very high; the ratio of invasions to species is around 0.5:1.0. And if we eliminate the speciose moas from consideration, there are about 70 species produced from between 43 and 58 invasions, and a ratio of 0.61-0.84:1.0, i.e. the figure for invasions is only a little lower than that for species in the fauna.
Apart from the moas (27 species), the bird groups invading New Zealand have not radiated or diversified to the extent seen in the birds of other islands and island archipelagoes (like the
Cyanorhamphus has four New Zealand species, Petroica has three and these are most diverse genera in the fauna. Thus it seems that the fauna has grown almost entirely by periodic invasion from Australia; a few of the invaders have split into several endemic species, mostly, it seems, by isolation on islands, and otherwise the endemic species have evolved phyletically.
Falla (1953) reported that the fauna is disharmonious. Although one tends to think of birds as easily able to overcome barriers to dispersal, Mayr (1964) suggested that birds differ drastically in their ability to cross water gaps, and found that large birds like ducks, herons and hawks cross water gaps easily, but that members of other families, especially small, forest-inhabiting land birds may ‘respect zoogeographic barriers extremely well’. Mayr (1965) showed that though there are 60 families of birds in New Guinea, only 16 of these make significant contributions to the bird fauna of Polynesia. Such differences in dispersal ability from group to group, are supported by an examination of the structure of the New Zealand bird fauna. It is especially true that the forest inhabiting species have diversified to produce subspecies on the various islands of the New Zealand region, suggesting little dispersal, even within the region. And comparison of the compositions of the bird faunas of Australia (donor) and New Zealand (recipient), suggests that differences in dispersal ability have profoundly affected the structure of the New Zealand fauna. In table 3, I have listed (from Keast, 1961) the number of species in the Australian fauna in each of the orders of birds which have representatives in the New Zealand fauna. Comparison of the percentages which each order contributes to the New Zealand and Australian faunas shows that the New Zealand fauna is by no means a random sample of the Australian, but that certain orders are over-represented, e.g. the Anseriniformes, while others are very much under-represented, e.g. Passeriformes. While it is likely that there are ecological reasons for some of the differences, it seems likely that variations in dispersal ability have also made important contributions. In addition to the small amount of
Although there is bound to be some debate about how critical the state of some species is, many New Zealand birds are extinct, or considered to be in danger of extinction. The 27 or so species of moa are all extinct, but otherwise the extinct or endangered species are scattered throughout the various orders. The quite well represented rails and ducks have been seriously affected, also some families of passerines. On a regional basis, much extinction has occurred in the Chatham Island fauna and comparatively little in Stewart Island. The faunas of the more substantial land areas in the North and South Islands have extinction rates intermediate between those for the Chatham Islands and Stewart Island (see fig. 1). The reasons for these differences are not obvious, although for the Chathams, the high rate may be related to fragmentation and flooding of a formerly more extensive land area (see Fleming, 1962c). The isolation of the Chathams is such that extinctions are not easily remedied by invasions from mainland New Zealand. This is not the case in Stewart Island, where species or subspecies not endemic to the island can reinvade easily from the South Island.
It is clear, from table 1 and figure 1, that there is a close relationship (not necessarily causal) between extinction and level of endemism. For each of the four islands considered, extinction is highest at the higher levels of endemism and lowest at lower levels. From this, it appears that the higher the level a given species is endemic to the New Zealand region, the more prone it is to extinction.
The value of the data at the ordinal level is of doubtful significance. When compared with the ratite birds anywhere else, New Zealand has an extraordinarily large number; but perhaps New Zealand acted as a centre for the radiation of large grazing birds, in the absence of grazing mammals and of mammalian and reptilian predators. And the land mass involved may have been significantly larger in the Tertiary than now. Sedentary, flightless birds may speciate more freely than their flighted relatives, but we can only conjecture here.
The foregoing results show that extinction has not occurred randomly in the New Zealand bird fauna, but that it is related in some way to evolutionary age. Species which have had a long evolutionary history in New Zealand seem now to be susceptible to extinction. This suggests some peculiarity in the evolutionary process in the New Zealand bird fauna, which in a time related manner affects the present viability of the species. It is acknowledged by several writers (e.g. Simpson, 1953, Darlington, 1948, Brown, 1957) that island evolved species, for a variety of reasons, tend to have ‘limited evolutionary potential’ (Brown, 1957), and this seems pertinent to the problem of island extinctions. MacArthur and Wilson (1967) have postulated that extinction may occur rapidly enough on isolated islands, to impose upper limits on the number of species present. Mayr (1965) noted that the bird
The present (i.e. last one or two thousand years) extinction rate for New Zealand birds must be higher than in former times. The existing rate of 45 recent extinctions (Williams, 1962) in a known fauna of 97 species (47%), with many more species endangered, and the significant bias towards the decline and extinction of the old, and survival of the recent elements, would have produced a much more recent fauna than we now have, had this rate been in effect for long. Clearly then, extinction has accelerated with the arrival of man in New Zealand, and perhaps because of his presence.
Fleming (1962a) postulated that there was much bird colonisation in the late Tertiary and little in the Pleistocene, but that the present invasion rate is high. Reasons for much invasion in the late Tertiary are not readily apparent, though a reduction during the Pleistocene is understandable. Falla's (1953) analysis showed that the fauna is largely of Australian origin, and we should expect few species to have been invading colder New Zealand from warmer Australia at a time when climates were deteriorating. Increased post-Pleistocene invasion may be related to rising temperatures, which would increase the favourability of New Zealand habitats for Australian birds.
In historic times there has been a remarkable amount of invasion. Fleming (1962a) recorded 12 species in the late Holocene prior to the arrival of the white man, and seven more established in the last
Zosterops australis, Notophoyx novaehollandiae. If the observed rate had been occurring long, saturation would have been achieved long ago, and the percentage of old endemics would probably be much lower than it is. Again, I think we are observing a high rate of colonisation as an ‘artifact’ of man's presence; this is due to the opening up of new habitats and increasing the niche diversity, as a by-product of agriculture and forestry, the maintenance of large areas of marginal (Wilson, 1965) or transient habitats and the establishment of new forest types. Examination of the record of stragglers to New Zealand, in Notornis (the journal of the New Zealand Ornithological Society), shows that a veritable stream of strange birds has been arriving in New Zealand from Australia and the Pacific, some species arriving repeatedly. Most of these have been solitary birds and few appear to have stayed long, but it has apparently only taken the provision of new habitats by man, to allow the species, which may have been straggling to New Zealand for centuries, to become established. The landscape of New Zealand has changed dramatically during the last 100 years, and an examination of the habitats of the recently established species will show the extent that man's activities have affected the rate of successful invasion. The welcome swallow (Hirundo neoxena) which is recently established in New Zealand, is reported breeding mostly in association with man; nests have been found mostly under bridges, but also in buildings, vehicles and boats (Edgar, 1966, Wagener, 1966, Turbott, 1965). How much the niches left vacant by earlier extinctions have been occupied by newcomers is not known.
Extinction rates on islands may have been high always, as a result of random genetic effects and lethal fluctuations in population size. The process of extinction in New Zealand has apparently been accelerated by the arrival of man, by his own predation, the introduction of other predators (mustelids, cats, dogs, rats, hedgehogs), the destruction and modification of existing habitats (deforestation and river disturbance), forest modification by browsing herbivores (many species of deer, plus pigs, goats and Australian opossums), and the introduction of many new bird species, with their diseases and parasites. All of these have probably played a role in initiating or accelerating the decline and extinction of New Zealand bird species. If extinction is primarily a product of the presence of man and his associated biota, then the extinction of the old endemics, which tend to be less active ground feeders, and weak fliers becomes more easily understood.
During the past one or two thousand years, there has been substantial decline and extinction of New Zealand land birds. The small land bird fauna is derived principally from Australia. Immigration, mostly if not entirely across the sea, began in late Mesozoic times and the fauna has been built up by immigration, followed mostly by phyletic evolution, with little speciation. The fauna is a fragment of the Australian fauna, selected by ability to cross oceanic barriers between Australia and New Zealand.
Analysis of extinction and decline of species, and of extinction and immigration rates shows that there has been much more extinction amongst the old endemics than amongst most recent species, and that both the extinction and immigration rates must be higher now than in pre-human times in New Zealand.
I am grateful to the following for reading and commenting on draft of the manuscripts:— Drs. K. J. Boss, P. J. Darlington, Allen Keast, Ernst Mayr, Giles
In a Country of such varied relief as New Zealand the distribution of plants is frequently controlled by the ecological factors associated with altitude. There is adequate geological evidence that this relief has persisted throughout the Quarternary. The existence of such relief introduces some doubt into the climatic interpretation of macrofossil floras, as the transport of plant remains from higher altitudes can result in the preservation at one place of fossil assemblages representing more than one climatic zone.
Plant remains are all potentially easily transportable by water to the lake or estuarine sediments which have preserved them in the past, and are preserving them today, but the possible distances of transport are less well known.
A second point of doubt concerns the proportion of vegetation preserved as fossils. The ultimate preservation of plant remains depends much on their relative resistance to damage, either by abrasion in transport or by microbiological decomposition during sedimentation. But little is known of the potential fossilisation of plants of the New Zealand flora.
In this paper, records of recent plant remains in mountain areas are compared with the distribution of source plants in such areas. Such comparisons can outline a direction to be followed in resolving the two different questions which must be answered before valid paleoclimatic interpretation can be made from fossil floras:
— Do the plant remains in a basin represent only the vegetation on the shores of that basin, or do they represent, as well, plants growing in a higher and colder climatic zone?
— What proportion of the total flora around the basin of deposition is likely to be preserved?
Sampling was done on and about Lake Pounui, which is at about 30 m altitude in the eastern foothills of the Rimutaka Range (N.Z.M.S. Sheet N.165). The lake is 1.7 km long and 0.8 km wide and not more than 10 m deep, and fed by streams entering it through aggraded
loc. cit.) is over 2 km distant.
Prevailing winds are northerly to westerly and are frequently strong. Southerly and easterly winds are less frequent and the lake is relatively sheltered from them by the surrounding hills. There is no record of rainfall at the lake but it is 1575 mm annually at Wairongomai, 8 km away, lying to the east of the axial range, as does Lake Pounui.
Vegetation: An assessment, based on an 8 point abundance scale, was made of the native vegetation around the lake. A map (Fig 1.) was compiled: the categories of vegetation being delimited by change in physiognomic species.
Sediment sampling: On the lake margin and in the shallow water of the swamps, samples were scooped from the bottom with a handheld canister of 400 ml capacity.
In open water samples were taken with a simple limnological dredge consisting of a canvas cone, with a steel reinforced mouth, and two of its three attached lines weighted. This apparatus, dragged from a dinghy, took samples each of about 10 m length of lake bottom and generally yielded about 100 cc of sediment. The location of sample stations is shown on Fig. 1.
The greater part of the lake shore is surrounded by extensive remnants of indigenous forest, by swamp vegetation in the aggraded valleys and by fire-induced scrubland dominated by indigenous species. The vegetation on the south-eastern shore has been converted to grassland farming but carries trees remnant from coastal forest. The vegetation (Fig. 1) consists of the following:
Hill forest dominated by Nothofagus solandri var. solandri with abundant N. truncata.
Swamp forest with Podocarpus dacrydioides and
Monocotyledonous swamp, with Typha muelleri dominant.
Remnant coastal forest south-east of the lake, with Myoporum laetum and
Leptospermum shrubland.
The first part of Table I shows the specific composition of these communities which are, apart from the coastal forest and swamp vegetation, a vegetation analogous to that described in detail by Druce (1958) in the western foothills of the Rimutaka Range.
There are two groups of samples: Firstly those from the swamps marginal to the lake, where plant remains deposited by direct fall and wind transport would be expected to dominate, with water transport being the case only in flood periods. The second group comprises those samples taken in open water, where there is a possibility of water transport before ultimate settling and preservation.
The Swamp Samples (Stations 8, 9). The matrix was a yellow brown clayey silt. Leaf fragments taken from the swamp are almost exclusively those of plants growing in the swamp or on dry land immediately adjacent. They represent the following plants growing in the swamp: Eugenia maire, Freycinetia banksii, Laurelia novae - zelandiae, Metrosideros perforata and
From dry ground adjacent have come:
Metrosideros robusta, Nothofagus solandri var. solandri,
N. truncata and their hybrid, and Pseudopanax arboreum; from more than 2 km away a solitary leaf of Nothofagus menziesii, either blown from higher country, or, more likely, carried from a riparian tree by the free-flowing portion of the stream above the swamp.
A total of 57 species was recorded in the communities around and on the swamp but only 9 are represented as potential fossils. Eight of these have coriaceous leaves, slow to decompose on the forest floor; only Pseudopanax arboreum has a softer, rapidly decomposing leaf.
The Lake Samples. The second group of samples, from the lake bottom, consists of Station 1 close inshore in shallow water, and Stations 2-7 from the open waters of the lake.
Station 1 was from shallow water equidistant from a rocky bank and from a marginal swamp. The matrix was entirely organic, of leaves and twigs, and yielding large quantities of the shrubs Leptospermum ericoides, L. scoparium and
Deeper water samples (Stations 2-7) were from a matrix of grey clayey silt. Plant remains washed from this silt represent the more common species of the vegetation of the surrounding hills: Coprosma rhamnoides, Leptospermum (2 spp.)
Underlining across the table indicates species found in swamp or lake sediments. Botanical names for the pteridophytes, gymnosperms and dicotyledons are those of Allan (1961) except where otherwise indicated.
vegetation on the lake shore. The leaves are all coriaceous. In all, the lake sediments yielded 8 of the possible total of 32 species available.
Notably absent from the lake sediments were remains of woody plants of the swamp vegetation. It can be concluded that fragments of such plants are effectively trapped in the dense foliage of the swamp floor plants. This filtering effect of the swamp may also account for the absence of any plant remains from higher altitudes.
Support for this contention comes from two localised records of plant remains from a free-flowing river and a lake fed by such rivers:
In the Mead River, a tributary of the Clarence (N.Z.M.S. Sheet S35) leaves of Nothofagus cliffortioides var. cliffortioides and N. fusca were found on the river bed 5 km from, and 600 m below, the lowest station of these trees.
On the eastern shore of Lake Taupo (N.Z.M.S. N103) leaves of Nothofagus menziesii were found, 30 km and 300 m below stands of this species. In both cases the rivers transporting the leaves are free-flowing, consequently plant remains from higher altitudes did not risk being trapped in swamps.
The results of sampling of potential basins of fossil deposition have shown that plant remains in a densely vegetated swamp are almost exclusively of plants growing in or close to that swamp. The exception, Nothofagus menziesii, of distant origin, both horizontally and vertically, could have been trapped by the swamp vegetation after stream transport over a distance exceeding 2 km.
In the lake sediments the plant remains represented only the dominant members of the vegetation surrounding the lake, and no remains were found that had been transported any distance to the lake. The absence of remains allochthonous to the lakeside vegetation supports the idea that the swamps in all the feeding streams act as filters, catching plant remains brought from higher country by these streams.
In the case of plant remains carried by unimpeded rivers, the transport of such remains from higher zones of vegetation is evidence that potential macrofossils can be carried considerable distances, and remain recognisable. In almost all cases the remains were of coriaceous leaves, a fact in agreement with general principles of fossilisation.
The nature of the sediments containing plant remains can also contribute to interpretation of fossil floras.
In the case of Lake Pounui, the sediments in the swamp and in the deep waters of the lake were all of fine texture, being those
Such relationships must be considered in the interpretation of macrofossil floras. Floras from deep series of uninterrupted silts and clays with highly organic strata are likely to have been associated with relatively slow flowing rivers and the presence of swamps, and are less likely to contain elements from higher zones of vegetation. Plant macrofossil beds intercalated with conglomerates should indicate the existence of more rapidly flowing rivers, and imply the possibility of inclusion in the fossil flora of plant remains from higher zones of vegetation than that around the basin of deposition.
I am grateful to those who helped in this study, both in the field and in the preparation of the manuscript: Mr. A. Rohde, formerly of ‘Wharekauhau’, Western Lake Road; Professor
Lichens are able to colonize almost any surface not permanently covered by water, ice or snow; and as many can endure extremes of heat or of cold that would prove fatal to other plants, they are to be found in all latitudes and at all elevations. Since they require little or no nourishment from the substrate they usually occupy such sterile substrates as rock, wood, bark, leaves, heath and peat soils, bricks, tiles, and even asphalt, where they have no competition with other plant types. Nevertheless most lichens are restricted to a single type of substrate, though others less fastidious may occupy two or more. Similarly some species are found only at one altitudinal level such as lowland, montane, subalpine, or alpine, while others range over two or more such zones. The only species known to occur from sea level to 9,000 feet is Stereocaulon corticatulum.
New Zealand covers the twelve degrees of south latitude between 35° and 47°, and has an altitudinal range of 12,000 feet, while the annual rainfall ranges from about twelve inches in some areas to as much as 250 inches in others. As a result there is a very wide range of ecological conditions reflected in an extensive lichen flora of possibly 1400 species.
Of these indigenous species about 20% occur north of the equator, some of which are in fact cosmopolitan. There is also a strong endemic element with some species ranging the greater part of the Dominion and others confined to localised areas such as North Auckland or Otago and Southland. Species such as Cladia retipora, C. sullivanii, or Chondropsis semiviridis are restricted to Australasia while others like Neuropogon spp., Stereocaulon argus, or Thelidia splachnirima belong to a subantarctic element. Some 200 species are common to New Zealand and Tasmania and a large number including many species of Cladonia, Menegazzia, Placopsis, Pseudocyphellaria, and Psoroma are indigenous both to New Zealand and Southern South America. A subalpine association met with both in this country and in Britain comprises Alectoria minuscula, A. nigricans, Cetraria islandica, Cornicularia aculeata and Solorina crocea.
A number of lichens are found only on coastal rocks, some are confined to subalpine habitats, and some to alpine rocks, but a majority of species, especially the epiphytic, belong to the lowland and montane area. The transition from subtropical rain forests to subantarctic beech forest takes place at approximately 2,000 feet, but
Alectoria, Agyrophora, Cetraria, Cladia, Cladonia, Dermatocarpon, Diploschistes, Hypogymnia, Lecanora, Lecidea, Neuropogon, Omphalodiscus, Pannaria, Parmelia, Parmeliella, Pertusaria, Pseudocyphellaria, Porina, Ramalina, Rhizopogon, Rinodina, Siphula, Solorina, Stereocaulon, Thamnolia, Umbilicaria and Usnea.
Relatively few collections of alpine lichens have been made. On Mt. Tapuaenuku in Marlborough (9,400 ft.), there is no permanent snowline, but on rocks between 7,000 feet and the summit J. Scott Thomson collected the following typical saxicolous lichens:— Alectoria pubescens var. reticulata, Agyrophora zahlbruckneri, Caloplaca elegans, Neuropogon acromelanus, N. ciliata, N. antarctica, Omphalodiscus subaprina, Stereocaulon corticatulum, and
There is much diversity among lichens in regard to their tolerance of shade intensity. The deeper the degree of shade within the forest the fewer the lichens present both of species and of individuals. For the same reason the lichens of the forest canopy differ from those on the lower trunks. However in Central Otago, the lichens on the southern or shady side of tall rock stacks far outnumber those on the sunny northern face but for different reasons. Lichens thrive best when moist and dry conditions follow in quick succession; hence, in areas both of scanty or of excessive rainfall the lichen flora tends to diminish. Foliose lichens thrive best and attain their maximum size in the calm, moist conditions of the forest interior, but fruticose and crustose species are most numerous on substrates exposed to full daylight. The only foliose lichens in alpine stations are small, black members of the family Umbilicariaceae.
Coastal rocks and cliffs support a copious and varied lichen vegetation some species being restricted to this station, some most
Lichina pygmaea var. intermedia, Arthopyrenia halodytes or A. balanophila—the two last named found only on the valves of barnacles stationed on the rock. Encrusting rocks and boulders from just below high tide levels to some distance above, the black thalli of V errucaria maura are common on many rocky coasts. Cliff faces below the lowest level of shrubs and herbs have as the dominant lichens other species of Verrucaria such as V. adguttata and V. aucklandica in the North Island or V. lacrimans and V. otagensis on the Otago coasts. The genus Placopsis, especially on volcanic rocks, is also common — P. gelida, P. parellina, P. perrugosa, P. trachyderma, and P. rhodophthalma, all being present.
Coastal rocks beyond the spray zone are frequently encrusted with extensive patches of the golden or reddish Xanthoria parietina, a species of wide distribution in similar stations overseas. Caloplaca has a number of coastal species such as C. archeila, C. acarocarpa and C. circumlutosa but much the most attractive species is C. etesiae. Though not restricted to coastal rocks Pertusaria graphica is the commonest and most widespread of six or seven coastal species. Other coastal lichens include many crustose species of
As in the previous station some lichens are restricted to the substrate and others occur elsewhere as well. The following species are wholly or almost wholly so restricted: —Caloplaca blastenioides, C. murorum, C. pyracea, and C. Thomsoni; Blastenia alboflavida, Lecanora jertilissima, L. pulvinaris, Leptogium plicatile, Placynthium nigrum, Porina rhodinula, Thelidium neozelandicum and Toninia tumidula. Other common lichens on calcareous rocks but not restricted to them include Bacidia subcerina, Buellia epipolium, Pannaria nebulosa, Parmeliella microphylla, Parmelia epheboides, P. perlata all but the last being crustose species. Physcia caesia is to be seen on limestone but occurs on rocks of all kinds. The coastal Verrucaria otagensis may be confined to calcareous sandstone but this needs verification.
The majority of mountain ranges in New Zealand are composed of metamorphic rocks such as greywacke or schist, but there are hundreds of square miles of mountainous country as yet unexplored in respect to the lichen flora especially at the upper subalpine and
Flat tops and southern faces of montane rocks bear Parmelia spp., Lecanora blanda, L. atra, Pertusaria subverrucosa, Rhizocarpon geographicum, Umbilicaria polyphylla, and Usnea glomerata; and near the base Pseudocyphellaria mougeotina, Coccocarpia cronia and Teloschistes jasciculatus. Common Parmelias are P. arnoldii, P. caperata, P. conspersa, P. perlata. P. prolixa, P. rudecta, P. rutidota and P. tasmanica and more locally P. epheboides, P. petriseda and P. waiporiensis. In rock crevices Cladonia capitellata, C. fimbriata and Cladia aggregata are occasionally present. The common species on the northern side are Anaptychia spp., Heppia guepinii, Physcia caesia and Caloplaca spp.
At subalpine levels the following saxicolous lichens occur on Mt. Maungatua—Lecanora blanda, Lecidea confluens, L. schistiseda, S. caespitosum all at 3,000 ft. as well as Umbilicaria vellea and Usnea torulosa. On the Kakanui Range Cetraria pubescens, Neuropogon ciliata, Parmelia mougeotina, Umbilicaria corrugata, and U. cylindrica are present at 5,000 ft., and on Mt. Ida U. decussata, U. hyperborea and Omphalodiscus subaprinus.
Without further research it is not possible to say which lichens if any are restricted to such rock types as granite, volcanic lavas, greywacke, etc.; but it can be said that on volcanic lavas (basalt, dolerite, etc.) Parmelia species are constantly present and in particular P. caperata, P. conspersa, P. perlata, P. cetrata, P. laevigata, P. perforata, P. saxatilis, P. trichotera and several others in section Melanoparmelia. Very common also are Placopsis gelida, P. perrugosa, P. rhodocarpa and P. trachyderma. Volcanic rocks form a congenial substrate for Candelaria vitellina, Dermatocarpon insigne, Diploschistes spp., Rinodina thiomela, Sterocaulon corticatulum and above 1,000 ft. S. gregarium. The writer has no information about high level lichens on the North Island volcanoes. On most rock types Buellia, Lecanora. Lecidea and Pertusaria are well represented.
A large number of lichens grow on bark, leaves, logs, shrubs and posts, those within the forest being of necessity shade tolerant to some degree. The dominant and largest lichens belong to the family Stictaceae. In different localities the species may differ but wide-spread and very common members of this family are Sticta filix, and S. latifrons, Pseudocyphellaria billardieri, P. carpoloma, P. chloroleuca, P. coronata, P. flavicans, P. fossulata, P. freycinetii, P. impressa and P. psilophylla, and in the wetter areas P. glabra and P. homeophylla.
Common but less conspicuous lichens on the bark of forest trees belong to the following genera — Collema, Coenogonium, Leptogium, Megalospora, Menegazzia, Myxodictyon, Pannaria, Parmeliella, Pertusaria, Phlyctella, Psoroma, Pyrenula, Sagenidium, Sphaerophorus, and Thelotrema. The lichen epiphytes of the subalpine beech forests mostly belong to the same genera with Sticta and Pseudocyphellaria still dominant, the usual species including Sticta filix, S. latifrons, Pseudocyphellaria coronata, P. fossulata, P. hirta, P. subcaperata, and less commonly P. rubella and P. obvoluta. In stations to which sunlight has access species of Parmelia, Ramalina and Usnea may become established.
Branches and twigs are here exposed to stronger light and support a lichen flora differing considerably from that within the forest. Here the dominant genus is Usnea (U. capillacea, U. xanthopoga etc.) often smothering the tree-tops (living and dead) so densely as to be visible at distances of a mile or more. Commonly the pioneers are crustose lichens (Arthonia, Arthothelium, Bacidia, Catillaria, Lecidea, Lopadium) soon to be followed by the larger fruticose or foliose lichens belonging mainly to Hypogymnia, Menegazzia, Pannoparmelia, and Parmelia, or to Usnea and Ramalina. In the wetter areas Sphaerophorus stereocauloides, Pseudocyphellaria coronata, P. hirta, may follow.
Because exposed to full light, the trees of open hillsides and similar stations also bear lichen epiphytes distinct from those of trees within the forest. Thus Parmelia spp. absent within the forest are perhaps the commonest lichens on trees in the open. Other conspicuous species in lowland stations include both Teloschistes chrysophthalmus on the branches, and Xanthoria parietina on the trunks of smooth-barked trees. The latter is usually var. incavata, a pale yellow variety that forms circular patches to 8 in in diameter. In damp localities species of Hypogymnia, Ramalina, and Usnea are frequent. The most common and conspicuous crustose lichen is Haematomma punicea known by its numerous white bordered pink
Lecanora, Lecidea, Opegrapha and other script lichens, any Pyrenula, etc. abound. Trees on the forest margin commonly have Parmelia perlata, P. trichotera and various species of Stictaceae less common on fully isolated trees.
Damp logs on the forest floor afford a congenial substrate for several species both of Leptogium and of Peltigera and occasionally for Pseudocyphellaria hookeri, all almost black in colour and containing a blue-green phycobiont. Sphaerophorus melanocarpus var. australis and S. tener may also occur here.
Logs and tree stumps in open stations in areas of high rainfall as at Cascade Creek on the road to Milford Sound, support a luxuriant lichen flora of a dozen Cladonia spp., Cladia aggregata, Sphaerophorus tener, and Stereocaulon ramulosum. On similar substrates in drier climates red fruited species of Cladonia (C. bacillaris, C. floerkeana, C. macilenta and C. pleurota) are common as are species of Parmelia, absent in the wetter areas. Brown-fruited Cladonias very commonly noted here include C. barbonica, C. cornutoradiata, C. pityrea, and C. verticillata. Wooden fence posts frequently support various species of Hypogymnia, Menegazzia and Parmelia and of Ramalina and Usnea.
Shrubs on the forest margin, on open hillsides, and in the subalpine belt each support a number of lichen species rare or absent in the other stations, as well as others common to all. Lichens found on the topmost twigs of shrubs on the forest margin are as a rule mainly species either of Parmeliaceae or Usnaceae, with Teloschistes and Haematomma as occasional associates. Usneas of this substrate include P. florida, U. inermis, U. simplex, and U. xanthopoga and less frequently U. contexta. Ramalina geniculata R. dilacerata, R. leiodea, R. menziesii and R. pollinaria are the more usual species on shrubs in the Otago area, associated crustose lichens being species of Lecanora, Candelaria, Haematomma, Pannaria, and more rarely Pyrenula.
Subalpine shrubs have as a rule a more numerous and varied lichen flora in which Parmelia and Pseudocyphellaria are often well represented, but a full catalogue for this substrate has not been compiled. Conspicuous species are Hypogymnia enteromorpha by reason of its largely black colour, and H. inflata because of its swollen, sausage-like thallus. Another distinctive lichen more common on the ground or on the bases of tussock grasses, but also present on shrub bases, is Pertusaria dactylina. In swampy places Usnea capillacea and U. contexta occur both on the ground and on low shrubs.
The dominant genus of epigean lichens is Cladonia, all of its seventy species occurring on soil at times, even though many are more usually seen on logs. Barren heath and peat soils commonly have a Cladonia cover of many species, the most frequently seen including C. borbonica, C. capitellata, C. carassensis, C. cariosa, C. cervicornis, C. chlorophaea, C. cornutoradiata, C. crispata, C. deformis, C. degenerans, C. fimbriata, C. gracilis var. chordalis, C. leptoclada, C. pityrea, C. pleurota, C. scabriuscula, C. subdigitata, and C. verticillata. The associated lichens are usually species of Baeomyces, Cladia or Stereocaulon.
Swampy and boggy subalpine soils are commonly inhabited by the three species of Cladia — C. aggregata and C. retipora on raised mounds, and C. sullivanii usually on wetter ground; and in Otago by Cladonia carneola and C. aueri, two species found also near sea level at Awarua and in Stewart Island. Raised mounds in the bog also in many places (e.g. Arthurs Pass) support Cladonia deformis, C. leptoclada, C. pleurota, C. pyxidata and C. subdigitata. The genus Siphula is represented by five or six species of which the commonest and most widespread is S. medioxima. In common with Thamnolia vermicularis the Siphulas are found both on boggy and grassland soils.
In grasslands Hypogymnia lugubris is frequently seen and more rarely H. enteromorpha. In Stewart Island and in Fiordland Sphaerophorus tener is plentiful and on the subalpine soils of Otago mountains Alectoria minuscula, A. nigricans, Cetraria islandica, Cornicularia aculeata and Solorina crocea are to be seen. Many species of Sticta and Pseudocyphellaria normally epiphytic are also to be found on subalpine grassland soils. Such include Sticta filix, Pseudocyphellaria aurata, P. carpoloma. P. crocea, P. delisea, P. durvillei, P. endochrysea, P. flavicans, P. leehleri, P. mougeotiana and also Lobaria laetevirens.
As a Non-Ecologist I am often impressed with the apparent contradiction between principle and practice in ecological research.
Approaches to ecology involve on the one hand, assertion of the involvement and complexity of animal relationships with their organic and physical environments. The literature shows on the other hand, that in marine ecology at least, actual research activity in field studies whether in the littoral or deep ocean, tends to be carried out at a relatively uncomplicated level. The complexities of association and community relationships are more often stressed in discussion and in theoretical approaches perhaps because field research as practiced is felt to be in some way inadequate.
The situation is more evident in marine ecological studies because of the difficulties of sampling in a mobile and often hidden environment which can obscure the detail of even the simplest relationships that are readily observable on land.
It may thus be that field studies in marine ecology have been less numerous and less effective than they might have been, for lack of clearly defined aims of study. The assumption by some workers that the natural situations they explored were dominated by inter-active processes may be unjustified and the failure of the community concept to act as a focus for study perhaps indicates that the concept itself, (meaning as it does, all things to all workers) has intrinsic defects. Some views of marine communities have almost implied an anthropomorphic conscious organisation among the organic components.
If ecology be the study of inter-relations among organisms and their organic and physical environments, then several kinds of investigation clearly throw light on these inter-relations and can be considered as contributions within the very broad definition of ecological study.
We can examine these studies for example with respect to the marine benthos, commencing with the organic factors. The first enquiry is of the uniqueness of a species and its existence in the area considered: then of the distribution of individual species or higher groups: and for example, of the availability of detrital and filterable food.
The parameters of the physical environment that can be examined are numerous and selection is generally made on grounds of feasibility of examination or measurement. In the fluid environment, we can for example measure distributions of water temperature and salinity and specific chemical components; daily,
The substrate can be characterised by examining amongst other variables, the grain size composition of sediments; the occurrence of exposed hard surfaces; the mobility of sediments; rate of deposition of sediments; and their chemical and petrological nature.
This sort of categorisation is typical of that explored in several current texts on ‘ecology’. The examples are of variables that can be sampled and measured directly. We thus have one essential element of ecological study — definitive ecology — that presents investigators with clear targets, the ultimate sum of which is the definition of the physical and organic environment.
Many present day approaches to ‘ecology’, seek correlations between pairs or groups of distributions of organisms or physical factors. This might be called associative ecology, following logically and readily from the availability of definitive material.
Similar distributions of organisms can be recognised and the nature and distribution of such associations examined. Correlations can usefully be sought of sediment type (defined perhaps by dominant grade component, by median diameter or by minimum percentage of one grain size) with occurrences of particular organisms. The most elementary correlations of animal with substrate, for example of various sessile animals with hard bottom, of filter feeders with strong currents and limited sediment supply are long established and well known. In most cases the correlation can be shown only in representational fashion. The properties of parameters that cause them to have the same distributional response in the total environment are mostly obscure, and generally not suggested by the associative method.
Both these segments of study are more properly ‘eco-geography’ than ‘ecology’. Both are dominantly static in concept since long or short term variations are generally not easily susceptible to study.
The third element of ecology endeavours to find events, processes mechanisms and responses that determine the correlations, and might be termed explanatory ecology. As an area of study this has suffered substantially from lack of achievable and acceptable targets for study in the marine field.
It is clear that such explanatory studies will produce results that by field methods are not demonstrably certain, but are the product of reasonable speculation and hypothesis. It is equally clear that the simple assertion of causal relationships does not constitute an advance in knowledge.
It is likely that two main sorts of determinative mechanisms can produce the animal in the place in which it is found.
Independent mechanisms (availability).
Interactive mechanisms (selection).
Among the first are for example the availability of larvae of suitable substrate, or appropriate temperatures.
Among the second are competition among species for area or volume of substrate, resistance to predation, and modification of the environment by one animal to permit the entry of another.
Orientation:— The targets of any ecological study must be arbitrarily set, for there are few natural limits. One might extend any field examination to the aquarium, and the laboratory, in search for the physiological basis for an animal's response to environmental demands. Equally individual or group behaviour may play a substantial part in determining the existence and viability of an animal in a given environment.
If the main aim is to interpret field studies then these can as a practical measure be examined as affecting a single species or a large group. The effect of the environment on the animal and that of the animal on the environment can be studied.
Alternatively one may, after recognising a particular association of species, or a group of animals with similar food demands, or a particular substrate niche, then look for the determinant factors in the environment selecting the observed fauna and the feed-back to the environment consequent on the existence of the selected animals.
Or one may proceed with the aim of recognising processes with less regard for the absolute species than for example for a mode of feeding or method of protection.
Scale of Application:— These aspects of ecological study can be applied to investigations of variability over large or small areas. The limited sampling of a large region will obviously produce broad-scale coarse results — contributions to zoo-geography and correlations of animal distribution with regional environmental differences. Such studies nevertheless lead directly to examination of fundamental questions of the nature of distributional boundaries and to consideration of the dependence of present situations on circumstances inherited from the late geological past.
Where closer observation is possible by camera and television or by acquiring undisturbed samples of large area and volume, then small areas of seafloor can be examined in fine detail and finer scale processes sought. Repeated sampling over small areas may well reveal successional or advective changes taking place in the fauna. Progress on all scales is needed.
The wide regional study has neither more nor less merit than detailed examination of a small area, the recognition and solution of taxonomic problems neither more nor less merit than determination of the sequence of events following a successful mollusc spatfall. Ideally it can be hoped that all the elements of the total study of marine ecology might advance in parallel with optimum interaction and feedback amongst them.
In Many Parts of the world diatoms can be found in sediment at the bottom of the sea. If we merely separate and identify their silica frustules or shells (described in ‘Tuatara’ by Cassie, 1959), we may be able to extend their classification and possibly indicate their mode of evolution. But if we also count them and find the proportions of species at different levels of sediment cores, the way is opened to fascinating interpretations of past distributions of water and land masses. These are based on whether the same species occurs at the present day in warm or cool currents, and more or less saline water. For instance Jousé. or Zhuze, (1966) has deduced the fluctuations of the Quarternary climate from cores in the Indian and Pacific oceans, as has Donahue (1966) for the Southern ocean.
The species composition of buried layers is more validly compared with the present surface of the sediment than with the plankton floating above, as those species most abundant in the plankton may be hardly found in the sediment; Round (1967, 1968) proved this for the Gulf of California. The presence of a particular silica frustule depends on its thickness and the time for which it drifted in ocean currents after losing its organic skin, (Lewin 1959). Much of the finer sculpturing is lost by all frustules before reaching the sediment. Freshwater diatoms are sometimes found in mid-ocean cores. This may indicate the possible extent of drifting according to Kolbe (1956) who found them in the Indian Ocean, or Zhuze et al. (1959) in the Southern Ocean, but Kolbe (1957) suspected that in his Atlantic cores freshwater species were wind-blown over 1000 km from the Niger swamplands. Unfortunately, some of the principal planktonic genera — Rhizosolenia, Chaetoceros and Bacteriastrum — have very thin walls to aid flotation, so they only occur in sediments as occasional spores of Chaetoceros and ‘ends’ of Rhizosolenia (see Round 1968). Ethmodiscus rex, on the other hand, is an elusive diatom in the plankton but strangely is dominant in subtropical sediments. As some diatoms can live by absorbing sugar solutions rather than by photosynthesising (Lewin 1953), Wood (1956) thought that live E. rex might inhabit bottom sediments. This now seems unlikely, so Zhuze et al. (1959) consider that its abundance is due to resisting dissolution and to being sorted by bottom currents. As diatoms are widely grazed by ciliates, copepods and other animals, many sinking frustules are broken (Raymont 1963).
Before we can decide on the geological ages of different levels of cores, or on past climatic and oceanic fluctuations, reasonable correlations should be sought in evidence from different groups of fossils. Riedel and Funnell (1964) found Tertiary radiolarians frequently reworked among Quaternary coccoliths and foraminifera in Pacific cores, showing this stratigraphy based on radiolarians alone would have been incorrect. Pollen spectra and diatoms from the Argentine basin show that a warmer land climate coincided with the presence of subtropical water masses (Groot et al. 1965). In New Zealand, a previous issue of ‘Tuatara’ (April, 1968) reported a symposium on the Tertiary climate here, at which evidence from such varied organisms as higher plants, corals, foraminifera, molluscs, coccolithophores and diatoms indicated that the mid-Tertiary climate became nearly subtropical before cooling down. It was suggested that although the earth as a whole was cooling, New Zealand's drift towards the equator compensated for this at the beginning of the Tertiary. It is essential for any study of this type to have accurate information on the present day distribution of the organisms involved.
Diatoms have been identified in water samples taken at various seasons from several places round the coast of New Zealand (Cassie, 1961, Taylor 1968) and New South Wales (Wood 1964) and the pattern of their distribution tentatively correlated with the currents and water masses described by Brodie (1960) and Rochford (1957). More complete pictures have been built up of the seasonal cycles in the
Several methods which do not involve counting individual cells are used to obtain an indication of the quantity of phytoplankton present in a water sample. Only the simplest measurements work in clear water which is free of silt or mud; these are the depth at which a white ‘Secchi disc’ can no longer been seen, dry weight, or colour shade estimation of acetone-extracted pigment from fine net samples (Hardy 1956). More refined techniques have been developed which separate active chlorophyll from its degradation products, or which attempt to measure actual photosynthetic rates by C14 carbonate uptake or oxygen evolution. These methods are used in assessing ‘primary production’ and they have been critically reviewed by Strickland (1965). Chlorophyll a values have been followed for two years at Kaikoura (Bradford 1968), but as Kaikoura is situated at the Subtropical Convergence variations of water masses tend to obscure the seasonal cycle. Cassie and Cassie (1960) estimated the primary production of their August bloom of Chaetoceros armatum and found it to be far greater than any previous measurements in the Pacific Ocean. Many ‘hit and run’ determinations of chlorophyll concentrations and primary production have been made in the oceans without much consideration of diurnal, seasonal or technical variations; the results are compared by Anderson and Banse (1961).
As the population of New Zealand increases attention will turn more towards exploitation of its surrounding waters, to fish-farming and to measurement and control of water pollution. Just as success in stock-rearing demands care and understanding of pastures, so developing fish-farming will need a deeper knowledge of the growth of algae. In this broad field biologists and others from very different disciplines will come across problems worth investigating not only for their local value but also for their worldwide interest.
I wish to thank Dr. J. F. Harper and Mr.
Indicate books of general interest.
Although Recent Authors (e.g., Stokell, McDowall, and Woods) have published much work on the taxonomy and distribution of the Galaxiidae in New Zealand, there is, with the exception of Galaxias maculatus (Hefford, 1931a, 1931b, 1932, 1934a, 1934b; McDowall, 1968), little information on the behaviour and life histories of these fishes.
The Galaxiidae generally are secretive fishes, and their ability to exist in large numbers undetected by all but the most assiduous observers helps to explain why so little is known about them. This fact, together with recent warnings of some possible future extinctions (Stokell, 1955; McDowall, 1966a; Skrzynski, 1968), makes it very desirable that their life histories and behaviour should be fully understood in order that any necessary measures can be taken to preserve them.
This paper presents data on growth and behaviour of galaxiid fishes kept in aquariums, which are compared where possible with what has been found to occur in the natural environment. These data are not the result of any particular programme of investigation
As the chief aim of almost all the attempts to keep Galaxiidae was to observe the behaviour of the fish, conventional aquariums with angle-iron frames and glass on all sides were normally used. They ranged in size from 24in. × 12in. × 12in. to 72in. × 15in. × 18in. The back glass was usually blacked out. Aluminium covers incorporating electric lights were used to prevent the fish from jumping out of the tanks. The lights were used only to inspect the fish at night or to promote plant growth when this was required.
Water used in the tanks was usually uncontaminated stream water. Sometimes tap water from the Wellington City mains was used, but this was left to stand for several days before being stocked with fish. Once a tank was established the water was rarely changed.
If the fish became infected with a disease or parasite which proved difficult to eradicate by the various methods described in most aquarium handbooks, an extremely effective technique was to clean out the tank, fill it with 10 per cent formalin, and leave it for two days with the contained air lines, filters, etc. The formalin was then drained off, and the tank was refilled with fresh water and drained several times over a period of a week; the tank was then ready for re-use.
Depending on the species of fish kept, air pumps were used to operate filters, for aeration, and for water agitation for fish which normally inhabit fast waters.
Aquariums were maintained at room temperatures, but if sickness in a fish was thought to be due to too high temperatures, the fish was removed to a cooler situation.
The tank bottoms were covered with river gravel and with rocks so arranged that fish had the illusion of cover while being visible to the observer. This was accomplished by laying flattish rocks one on top of the other to form small caves running from front to back. Some tanks were well planted with water weeds, which gave additional cover, but this was not essential, as the galaxiids usually inhabit waters devoid of higher plant life.
Fish were measured (length to caudal fork) after being narcotised in a mild solution of MS 222.
The fish were fed with a wide variety of live foods augmented with some patent dried fish foods, minced liver, and fish. Whiteworms (Enchytraeus sp.), Daphnia, ostracods, and copepods were given to whitebait and small fish; earthworms, woodlice, crushed snails, grubs, caterpillars, flies, and moths — whatever was most easily available at the time — were given to the larger fish. The
For a constant supply of live food, whiteworm cultures were most satisfactory, and these were fed on slightly moistened waste bread.
Young fish usually adapt to aquariums better than older fish, and whitebait — which Woods (1963) described as ‘the transparent, free-swimming and shoaling juveniles of at least five species of galaxias’— are abundant at a time when they are probably most adaptable to aquarium life.
The transparent juveniles of five species having marine whitebait (McDowall, 1964, 1965, 1966b, and in press) are the subjects of this section. They enter estuaries in mixed shoals on the flood tides during spring and can be obtained all round the New Zealand coasts. Although species composition varies from place to place (McDowall, 1965), and all except G. maculatus appear to be rare on the east coasts of both islands, the most likely places to obtain the different species can be predicted (McDowall, 1965; Woods, 1966). Galaxias brevipinnis tends toward snow-fed rivers, but G. fasciatus, G. postvectis, and G. argenteus prefer warmer bush-and swamp-fed waters. Galaxias maculatus will be found in all types of rivers except those running off steep hill faces directly into the sea.
Whitebait were safely transported in water in insulated (foam plastic) bins or in water sealed in plastic bags protected with sawdust or some other suitable material in a box or tin.
Released into a tank, whitebait will begin to feed in a few hours, especially if the tank has been ‘seeded’ with Daphnia in advance.
Successes in rearing batches of whitebait were variable, and the reasons for this are not understood. With G. maculatus, rearing was almost always 100 per cent successful, but with the other species there was sometimes failure. Galaxias fasciatus usually settled in well, provided that the depth of water was kept down to 10in. or less, but these fish were extremely slow growing in a tank, and in a mixed batch of fish were at an early disadvantage, being the smallest of the whitebait. They sometimes sickened and died off in numbers, even when kept separate from other species.
Although two separate small lots of G. postvectis all lived, less than 50 per cent of all whitebait introduced into tanks and known to have been this species survived. Mortalities were unexplained, deaths occurring at temperatures between 15.6 and 19.2°C, though more than 50 per cent of a smaller number of G. brevipinnis under the same conditions survived.
The fourth species of whitebait. G. argenteus, has not been handled in sufficient numbers to make comparisons, but of three whitebait known to have been G. argenteus, two were reared to the late immature stage and the third died under the same circumstances as the G. postvectis referred to above.
Galaxias brevipinnis adapted surprisingly easily to aquarium life, considering the fairly rapid waters which it normally inhabits. Woods (1966) stated this species died at temperatures between 17 and 20°C, but the author found it capable of withstanding 19°C for periods of a day or two, and up to 23°C once the fish had been established for a few weeks. At temperatures below 17°C this species usually attains the late immature stage without loss.
In nature, with the exception of G. maculatus, the whitebait shoals break up at some stage after entering fresh water, and the different species occupy their own distinctive habitats.
Galaxias maculatus remains in the lower, easily accessible reaches of the rivers or may find its way into coastal lagoons and swamps. Extensive rapids, low falls, and modern bridge culverts with a free fall at the outlet bar its upstream progress. Galaxias fasciatus and G. brevipinnis often inhabit streams with a flow of less than about 10 cusecs — the former in pools and the latter in the fast ripples — and both are capable of surmounting large falls while they are migrating upstream. Galaxias fasciatus is also found in swamps. Galaxias postvectis has been caught mostly in the pools of bush streams, but its adult habitat is not really known. Galaxias argenteus is found mostly in slow streams and deep swamps, but it has also been taken from some lakes.
This fish is probably the best known of all the native freshwater fishes, and this is due in part to the ease with which it can be reared in almost any kind of container. To the student it is important, because its growth to first maturity in an aquarium can be comparable with that of fish in the natural environment; it is therefore useful as a guide to the suitability of conditions in the aquarium.
Inanga have a naturally short life cycle (Burnet, 1965; McDowall, 1968). In a tank many of them died after about six months, when they were 1 + years old and fully mature. They then measured from about 55 mm to about 80 mm. However, death did not always occur at this time, for some fish were found to survive for a further twelve months, maturity either being delayed or gonad resorption taking place, a facet worth further study. These fish attained lengths of 110 mm or more. These age/lengths for 1 + and 2 + years fish are comparable with data on fish from the natural environment (Burnet, 1965; McDowall, 1968). The occasional fish which
Occasionally G. maculatus females in a tank were found by the author to be spent, but this was a rare occurrence and the spawn has not been seen. Presumably it was eaten by the occupants of the tank.
In a large tank (72in. × 15in. × 18in.) inanga formed a shoal, which included other species, and remained in mid-water except in temperatures below about 10°C, when they tended to become less active and sometimes lay on the bottom. Very large individuals, too, tended to leave a shoal and remain inactive under cover indefinitely. Temperatures as high as 24.5°C did not appear to inhibit normal activity.
The behaviour of G. maculatus toward all other species of fish was pacific unless the other fish was small enough to be eaten. Inanga fed readily on most animals small enough for them to eat, either dead or alive, and would also take patent dried fish foods. They fed from the surface, from mid-water, or from the bottom with impartiality, as has been found with wild fish (McDowall, 1968).
Galaxias maculatus was sometimes introduced to an aquarium as an adult, but it was very often infected with whitespot (Ichthyophthirius), and though this parasite may be dealt with in a number of ways, it was a great nuisance and highly infectious.
The banded kokopu were much slower growing in an aquarium than any of the other whitebait species. Captured as whitebait at about 45 mm in length, they attained only 60-65 mm in a further twelve months. The only two specimens which survived to twenty-six months reached lengths of 103 mm and 104 mm, but one fish, which was 72 mm long when caught in April, increased by only 7 mm in the subsequent sixteen months. This was slower growth than the species attained in a stream near Wellington, where 1 + years fish ranged from about 70-100 mm, and 2 + years fish about 105-125 mm (Fisheries Research Division, unpublished data).
In the wild a few male G. fasciatus at lengths of only 62 and 63 mm were found to be ripe during April after what is assumed to have been only about six months in fresh water. Females have been known to shed spawn in a tank after eighteen months in captivity, having been well past the whitebait stage when captured (it is not known if the eggs were fertile, as they were eaten by adult fish before development could occur (
In the pools of small streams banded kokopu tend to form shoals, and over a dozen fish may be seen which may span a large size range. In tanks these fish were generally solitary, though the species was not kept in numbers on its own and may well have shoaled under these circumstances. In a large, deep tank (72in. × 15in. × 18in.), with a mixed population of fish, a single small G. fasciatus remained near the surface of the water and was easily intimidated by other species. In smaller tanks G. fasciatus was better conditioned and lived peacefully with G. maculatus or G. postvectis and with Retropinna spp. and Gobiomorphus spp. of similar size range.
Under aquarium conditions the banded kokopu exhibited the same feeding habits as the inanga, but was more adept at catching large insects on or just above the surface of the water. It seized big live moths by the abdomen, dragged them down, and broke off the head and thorax of each by dashing the insect against a rock. It then slowly swallowed the abdomen, part of which protruded from the fish's mouth for some time afterward.
The author has had little success with the adaptation of adult Galaxias fasciatus to tank life. The fish have invariably broken out with a fungus (Saprolegnia) a few days after capture, even when no injury was apparent, though this has not been the experience of G. fasciatus in covered bath tubs. However, rearing from the whitebait may offer the most satisfactory means of acquiring adult fish, and this would probably be most successful if the G. fasciatus could be separated from the other whitebait at an early date.
The least known of the whitebait species, this kokopu has been taken by the author in large numbers as whitebait from the Buller River, and there may be substantial populations of it in the deeper pools of this river and its tributaries.
Once past the whitebait stage, this species appeared well suited to aquarium life. In tanks longer than 3ft. 6in., it attained lengths of 105 to 121 mm after twelve months' captivity, and one fish reached 135 mm after twenty-four months. No data are available on growth in the natural environment, but the observed growth was good, compared with that of the other kokopu.
After the early deaths of some fish of this species (at the whitebait stage already referred to) the survivors thrived in temperatures which did not drop below 21°C for several weeks during summer and which exceeded 23°C at times. As whitebait and early juveniles they were mid-water swimmers, but after about two months they took up solitary positions under cover. At this stage there was some skirmishing over choice of refuge, but this soon ceased, and though the fish met when being fed, there was little aggressiveness between them, and even less towards other species.
Later, however, when the fish had been in fresh water for about twenty-one months, prolonged battles occurred near the surface of the water, with the combatants circling and biting at each other. It is not known whether these fights were due to the increasing size of the fish and their need for more territory or if they were connected with approaching sexual maturity, but one fish which died of disease at twenty-two months was found to be a ripe male. It was 126 mm long — only about half the size of some specimens which have been taken from the wild.
The short-jawed kokopu is by nature a bottom feeder, but it readily took food which was still falling through the water; it also learned to go to the surface for food if it saw other species doing so, though the under-shot lower jaw caused it to miss often. The fish gradually lost the habit of rising to the surface as they grew bigger. They were never observed to eat other fish or try to do so, even when small bullies (Gobiomorphus spp.) and whitebait were placed in the tank with them.
No attempt has been made by the author to adapt adult Galaxias postvectis to tank life, but G.
It was probably G. argenteus which Graham (1956) kept for a few days in a salt water tank. Although he described it as G. fasciatus, the measurements given — 15in and 2½lb — are far greater than any other measurements recorded for this species.
Galaxias argenteus is the largest growing of the New Zealand Galaxiidae, but it may be mistaken for the banded kokopu during the early immature juvenile stage. Both McDowall (1966b) and Woods (1968) stated that the markings of juvenile G. argenteus are quite distinct from those of other species, but neither of them had examined very many juvenile G. argenteus, and both the young and adults of G. fasciatus may vary (see Woods, 1968, fig. 7). If there was any doubt about the identity of small live striped kokopu, their behaviour in a tank quickly indicated the presence of G. argenteus, for they were very pugnacious and harrassed G. fasciatus almost constantly.
There are very few records available of small G. argenteus from the wild — possibly because they have been mistaken for the banded kokopu — and there is no information on growth rate. Only a few specimens have been kept in tanks, and one reached 95 mm after fourteen months in fresh water. This appears to indicate a slow growth rate when it is considered that many fish of this species grow to 300 mm and that much larger specimens have been recorded. G. G. argenteus is great and probably exceeds six years.
A large G. argenteus is a hungry feeder once it has settled down, but adults may take several weeks to do this, and then only come out from cover to feed at night. The steady reduction in numbers of small fish in the same tank as G. argenteus indicated that it was to some extent piscivorous, though its apparent slow movements seemed ill suited to the catching of agile species like G. maculatus and Retropinna retropinna, which were among the missing fish. It has been supposed that G. argenteus normally takes these fish from ambush, and G.
An apparent shunning of light, exhibited by the adult giant kokopu during the first weeks of captivity, is not always a feature of its behaviour in the natural environment. Although it may often be seen at night by torch light in places where it is not to be seen during the day, it may sometimes be at the surface of quiet, deep swamp pools during the day. At such times it readily takes a baited hook and can be caught far more easily in this way than by any other method.
Like the banded kokopu, G. argenteus would take its food from any zone of the water, and worms, crushed snails, raw meat, and moths were all acceptable.
Adult giant kokopu adapted to tank life fairly well and did not seem to be as prone to disease as G. fasciatus.
This fish is an inhabitant of ripples and cascades, where it dwells under stones, and the fact that it settled fairly well to aquarium life was a paradox which it shared with the torrent fish (Cheimarrichthys fosteri).
Captive taiwharu made good growth for the first year, and lengths in excess of 90 mm have been recorded in this time, with one fish reaching 106 mm after fourteen months in captivity. These measurements are comparable with data on a small population in a Wellington stream where the same year class ranged from about 87 to 103 mm and from 78 to 102 mm in November of two successive years (Fisheries Research Division, unpublished data).
As opposed to the satisfactory growth rate for fish captured as juveniles, a fish which was 80 mm long when first captured in September 1965 (1 + years) had increased by only about 15 mm during the subsequent three years—a fact which highlights the desirability of obtaining fish while they are juveniles.
A specimen of G. brevipinnis has been kept in captivity for six years by G.
In behaviour the captive taiwharu was an inquisitive fish, constantly active, as was noted by Woods (1963), and after capture as whitebait it shoaled freely with such other fish as G. maculatus and R. retropinna for many months — behaviour which has certainly not been observed in the natural environment, where, as an adult, it would be unlikely to overlap the habitats of these fish. If a much larger fish of another species was placed in the same tank with it, G. brevipinnis reverted to an undercover existence and was not seen for days at a time
Galaxias brevipinnis is naturally a bottom feeder, but like G. postvectis it learned to take food from the surface of the water and became more adept at it than did the latter species. Owing to its small mouth it needed to be supplied with reasonably small animals as food. These were supplemented with dried food, which the fish learned to take.
Of the Galaxiidae dealt with in this paper the dwarf galaxias at first proved the most difficult to keep alive and healthy. Several early attempts to keep this fish were entirely unsuccessful, the longest survival being three months.
Current work, however, indicates that this species may have only a two-year life cycle (C. L. Hopkins, pers. comm.), and this may account for some of the early adult mortalities, though not for similar losses of fry.
Recently, success has been gained by keeping these fish in a cool room, in shallow water not more than 2 or 3in. deep and well agitated by aerators. Gradual increase in the depth of water after a time apparently caused the fish to leave their cover and swim about in mid-water, where they were unbalanced and distressed.
Four specimens have now been held in tanks for ten months, three being young adults when first caught and the fourth a fry. At the beginning of August spawn was laid by one of the three adults, but the eggs failed to develop and it is thought that no male fish is present (C. L. Hopkins pers. comm.).
Free-swimming fry of G. divergens captured in the field may be reared on very fine dried foods, but once the fish have taken to the bottom, live foods are necessary, and white worms have proved satisfactory. Currently, free-swimming fry are being fed on newly hatched brine shrimps.
This species does not occur in the North Island, and the author has had only six live specimens. One died shortly after arrival in Wellington, and a second was eaten by a G. argenteus during an experiment, but the other four survived for twenty months before dying of a severe infection of whitespot.
The average increase in length of the four latter fish was 14 mm over the twenty months (means of 72 and 86 mm at capture and at death respectively), but it is not known how this would compare with the growth of fish in the natural environment.
The behaviour of this species in tanks varied greatly according to circumstances, but it was generally more active than was expected for a fish which normally dwells under cover. In a large tank with 16in. of water depth and with a variety of shoaling and bottom-dwelling species G. vulgaris would spend most of the time actively swimming in mid-water with the shoaling fish. This was very surprising, since Benzie (1961) found that adult G. vulgaris exhibited no intraspecific social behaviour.
In smaller tanks with less than 12in. of water G. vulgaris was found to be aggressive toward such mid-water species as smelt (Retropinna retropinna), but shy of bottom dwellers like Gobiomorphus huttoni. It spent much time swimming around just off the bottom, with its nose down on the gravel. If the tank contained no other species, it would rest on the bottom, either under or near to cover, but it became very active when food was offered.
Although mainly bottom feeders, captive Galaxias vulgaris would take food from the surface, as this species has been observed to do in the quieter waters of its natural habitat (Benzie, 1961), Both live insects and dried foods were taken readily by captive fish.
Davidson (1951) gave an account of the keeping of the brown mudfish in aquariums, in which she met with varied success. Contrary to what is usual with most other fish, the adults seem to adapt to tank life far better than fry and juveniles. Young fish captured by the author have usually died within two months, having grown an average of 6 mm in the interim, and no visible cause of death has been noted.
Growth of adult fish appeared to be satisfactory, but it has not been possible so far to compare it with that of wild stock, which may vary considerably in any case according to whether or not drought conditions force the fish to aestivate.
Tank breeding of these fish is possible, for the author currently has three juveniles which were first observed as fry on July 27,
Neochanna apoda has been observed to spent the daylight hours resting on the bottom of the tank, under weeds, stones, or whatever cover was available, with several fish sharing the same cover and lying packed close together in physical contact. At night they were seen to emerge and move slowly around the tank or lie motionless among the weeds close to the surface of the water as described above. If the tank was aerated, they would sometimes swim actively up and down the stream of bubbles emitted by the air line.
Although up to seven mudfish have been kept in one 30in. × 12in × 12in. tank, little aggressiveness has been noted among them, but M. M. Davidson (pers. comm.) reported an instance of cannibalism among fish which were being transported after capture.
On several occasions when a single N. apoda was placed with other species it became extremely aggressive (Eldon, 1968) and entered into battle with species of Galaxiidae, Retropinnidae, Eleotridae, and small eels, with which it was confronted. However, possibly because of its rather small mouth, it seldom inflicted any real damage. Paradoxically, when a single eleotrid was placed in a tank containing several mudfish, to enable a study to be made of the reaction of both species, it was completely ignored by the mudfish.
Whiteworms were a convenient food for mudfish and were taken readily, but the fish would also take earthworms and some insects provided that they were not too large.
The author has no personal experience of this species, but W. Skrzynski (pers. comm.) kept four specimens in a tank for three and a half years, and they grew from an estimated 50 mm at capture to an average length of 90 mm in that time.
These fish did not breed, though both sexes were found to have been present when the fish were examined after their deaths; death may have been premature, as all four fish died shortly after they had to be moved to another tank.
There was no aggressiveness among the black mudfish, which were kept in 2in. of water in a 24in. × 12in. tank.
Although supplementary food in the form of whiteworms was given to the N. diversus from time to time, the tank was largely selfsupporting, the fish apparently feeding on a population of snails (Potamopyrgus sp.) which maintained itself on the plant and algae growth.
Many species of Galaxias will live for a considerable time in a suitable aquarium and there is no reason why spawning behaviour of some of the species should not be eventually observed in captivity, especially if some form of water circulation can be maintained. In the event of successful breeding techniques being evolved it may be possible to save seriously threatened species, such as G. burrowsius, from extinction (Skrzynski, 1968).
If tanks are to be used to study the growth and behaviour of a single species of Galaxiidae, additional tanks for study of interspecific behaviour are an advantage. The main fault with the author's arrangements has been too much mixing of species, partly to observe reactions and partly because of shortage of space. This situation frequently causes trouble when one species dominates the tank or falls sick and affects the others. The only exception to this rule of segregation would be the keeping of one or two G. maculatus with the study fish to act as controls.
Except for G. argenteus and possibly G. postvectis only shallow tanks of 12in. or less are required, but the surface area should be as large as practicable.
Dried foods and raw meat may be used to supplement the fish feed, but live foods should always form the major part of the diet.
Details are given of the behaviour and growth of nine species of Galaxiidae kept in captivity, and these are compared with data collected in the field.
I thank those people whose personal communications helped to complete this paper, particularly Mr. G.
by Margaret A. Leslie.
Published by A. H. and
One of the richest and most exciting fields for the study of a biological community is undoubtedly the rocky shore. Such a study is often undertaken as part of the courses in general science and biology in our secondary schools, and Margaret Leslie's book is certain to be welcomed by both students and teachers as a most helpful aid to the enjoyment and success of this study.
The introduction provides a useful survey of the environmental conditions encountered by the organisms of the rocky shore, and the reader is introduced to some of the problems as well as to the advantages of living in such surroundings. This allows the reader to see the animals in relation to a particular habitat rather than as a collection of unrelated and structurally distinct organisms.
There is also much useful information in the appendix on methods used in studying such an area. This includes a list of equipment, needed, methods of constructing a quadrat and transect, sampling, recording results, and notes on the preservation of organisms. The methods are outlined concisely but in sufficient detail to allow students to carry out their investigations without the close supervision of someone more experienced.
As the title indicates, the major part of the book is devoted to a description of the more common animals of the rocky shore. They are grouped according to phylum: the distinctive features of each phylum are described and any technical terms are explained. A particularly pleasant feature of the book is that on the page facing the written description of any organism is a labelled diagram with a scale included. The textual description which emphasises the distinguishing features of an organism, together with the illustration should enable the student to identify the organism quite easily. There are no photograph but this deficiency is offset by the clarity of the diagrams. An excellent glossary of technical terms as well as a comprehensive index will help any student who has difficulty with the text.
The author states that her book is aimed at meeting the requirements of sixth-form biology students, university and training college students, and amateur naturalists’. She is to be congratulated on producing a book which is certain both to find a place on the library shelves of our schools and colleges, and also to be used by nature lovers who enjoy a visit to our rocky shores. The bibliography is interesting and should suggest a considerable amount of further reading for the student. The price of $2.50 is very reasonable for such a book.
Owing to increased printing costs the subscription to Tuatara, which had not changed since 1962, has been increased from $1 to $2 per volume. The editorial committee is very grateful to those subscribers who have eased our financial situation by paying their subscriptions in advance and especially to those who made additional contributions, which in some cases were extremely generous.
Tuatara will no longer carry advertisements as in recent years the financial return from these has been very small.