736 VERNBERG 



(Shepard and Lutz, 1976). Ingram and Jenner (1976) also reported 

 on the influence of photoperiod and temperature on two species of 

 Odonata. Species and seasonsil differences were observed, but, 

 generally, development occurred more rapidly under long-day 

 conditions. 



In 1975 Lough reevaluated the literature on the combined effects 

 of temperature and salinity on survival and growth of bivalve larvae 

 using response-surface techniques. Generally, tolerance to both 

 temperature and salinity were greater in the late veliger larvae than in 

 the developing embryos. Each species had its own specific character- 

 istic response pattern, which changed as the larvae approached the 

 adult condition. In all species there was a significant temperature- 

 salinity interaction in relation to growth. Cain (1975) subjected 

 larvae of the bivalve Rangia cuneata to combinations of temperature 

 and salinity. Embryos were relatively insensitive to thermal shock. In 

 addition, growth was reduced in lower salinities. The combined 

 effects of temperature and salinity resulted in a higher level of 

 mortality than the sum of the mortalities for either of the two 

 factors alone. Recently, Fish and Fish (1977) found that embryonic 

 development of the prosobranch snail Hydrobia iduae was influenced 

 by temperature and salinity. Data were analyzed by fitting surface 

 responses. Hatching was recorded in salinities ranging from 8 to 

 60\o ^'^^ ^t temperatures up to 35° C, but the minimum incubation 

 time (5 days) was found over a range of 13 to 41% q salinity and 

 22.5 to 33°C. 



Fish development is also influenced by environmental factors. 

 Hamor aiid Garside (1976) subjected embryos of the Atlantic 

 salmon, Salmo salar, to various combinations of temperature, 

 dissolved oxygen, and water exchange. Survival during embryogenesis 

 and during the hatching period was limited primarily by oxygen 

 supply. Water exchange and temperature were next in importance, 

 but all three were statistically significant in affecting development. 

 May (1975) studied not only the effect of temperature and salinity 

 on fertilization, embryonic development, and hatching of the marine 

 fish Bairdiella icistia but also added the factor of parental salinity. 

 Fertilization was blocked at salinities of 10% o ^iud below. Tempera- 

 ture and salinity interacted, with development at high salinities being 

 most successful at low temperature and development at high 

 temperatures being most successful at low salinities. The overall 

 viability of eggs produced was greatly influenced by the stage of 

 maturity of the spawning female. The salinity tolerance of eggs was 

 not significantly changed when adults were matured sexually in 

 diluted seawater (15%o salinity). 



