Combined effects of temperature and salinity on Hemigrapsus edwardsi (Hilgendorf) and H. crenulatus (Milne Edwards) from Wellington Harbour, New Zealand. Technical Report
- Author
- Hicks, G.R.F.
- Year
- 1973
- Journal / Source
- Journal of Experimental Marine Experimental Biology and Ecology
- Volume
- 13
- Pages
- 1-14
- Keywords
- Crabs, intertidal, salinity, estuarine, soft substrates, Wellington Harbour
- Summary
- Tolerances to combined levels of temperature and salinity were studied in the New Zealand intertidal grapsid crabs Hemigrapsus edwardsi (Hilgendorf) and Hemigrapsus crenulatus (Milne Edwards). Field sampling established the seasonal environmental variation in temperature and salinity to which these species are subjected within Wellington Harbour and provided a basis for the choice of experimental levels. Temperatures of 5, 15 and 25°C and salinities of 0, 15, 35 and 45‰ were combined to produce 12 combinations to which animals were subjected in the laboratory. Estimated optimum conditions of temperature and salinity based on the ‘fitted response surface’ method are presented for summer and winter populations of both species. H. edwardsi survived better at low salinities only at low temperatures. It is postulated that estuarine penetration of this species in Wellington Harbour is prevented by the inability to withstand low salinities at higher temperatures. H. crenulatus survives in marine conditions when the temperature is high; a combination of low temperatures and low salinities is detrimental and the species is suspected of burrowing in the substratum to avoid these lethal conditions during colder months.
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