Further Evidence for Seasonal Breeding Cycles in Deep Sea

INDICATION of cyclic reproductive activity in abyssal benthic organisms was revealed in an analysis of data on isopod crustaceans from the Scotia Sea near Antarctica1. Recent studies2 of deep-sea echinoderms have provided further information about seasonal breeding in the uniform climate of the deep-sea environment. It might be possible that some abyssal species propagate throughout the year; however, Orton's view3 of continuous breeding as a general rule for all animals inhabiting stenothermal regions such as the polar seas and tropics, as well as the deep sea, is not true in the light of present findings. Hult4, basing his ideas on his collections of Skagerrak isopods, argued that a rich population sample containing reasonably equal proportions of all stages of female in any given locality suggests that there is breeding throughout the year. Such samples are seldom seen in deep-sea collections and, as pointed out earlier, females in reproductive stages are usually very rare in abyssal collections1.