Terminology

Hammett & Hammett (1945) regard the word 'season', applying to summer, winter, spring and autumn, as a "waste-bucket word of loose usage", unless limited to the interval between a solar equinox and a solar solstice. For the present paper we have not defined the word with the exactitude of Hammett & Hammett. But we do define it specifically with regard to Wellington Harbour in terms of approximate temperature range, as follows: winter, 9°C-12.5°C; summer, 15.5°C-20°C; autumn and spring, 12.5°C-15.5°C.

There is no doubt that loose usage of the words winter, summer, etc. can be misleading. For example, peak production of Obelia medusae in Wellington Harbour is winter, namely July-August (= temperature 9°C-12.5°C, latitude, 41.2°S). In Perseverance Harbour, Campbell Is., it is summer, namely February-March (= temperature 9°C-10°C, latitude 52.3°S). Thus, if peak production of medusae is not also defined for Perseverance Harbour in terms of temperature and/or latitudinal range, it could imply a correlation between the season of peak production in this southern hemisphere locality, and the season of peak production recorded for northern hemisphere localities. Formation of gonangia reaches a peak through increasing warm water (summer) conditions in the northern hemisphere (Hammett & Hammett, 1945: Russell, 1953). In the southern hemisphere the peak is reached through decreasing temperatures. When seasonal terminology is disregarded, Perseverance Harbour is seen to be similar to other southern hemisphere localities in the New Zealand region where maximum production occurs in cold water temperatures about 9°C. That is, winter, in seasonal terms of the lower latitudinal range of Wellington Harbour waters.