Abstract
This paper is part of a continuing study of intrinsic controls of growth. develop ment and, implicitly, productivity of marine zooplankton. Copepods are particularly suitable for comparative studies of embryonic development rate because most spe cies hatch at a morphologically equivalent first naupliar stage. The effect of tem perature on size varies markedly among different geographical populations of the copepod Pseudocalanus minutus KrØyer, and it was assumed that embryonic devel opnient rate would vary likewise ( McLaren, 1965a ) . However, after trips in the spring of 1965 to Woods Hole, Mass., Halifax, N. S., and Millport, Scotland, it was clear that embryonic development rate varied only slightly, and attention was directed to other species. A summer trip to Frobisher, N. W. T., was made par ticularly to secure data on a large-egged form of Pseudocalanus living in Ogac Lake, a warm, landlocked fiord off Frobisher Bay (McLaren, 1965a). Successful experiments at Frobisher on the large Calan'us gla.cialis Jaschnov (see Grainger, 1961) were doubly useful because o@published data on C. finmnarchicus (Gunnerus) from Scotland and Norway (Marshall and Orr, 1953). A l)rief return to Halifax in April, 1966, added two niore species, Acartia claitsi Giesbrecht and Tortanus discaudatus (Thompson and Scott). Although the number of forms studied is rather small, the results are published at this time because they seem to have some general and theoretical interest. More work will be done to confirm the results and hopefully to extend their predictive value to other developmental stages. Use will be made of Bélehrádek's (1935, 1957) equation, in which rate of a metabolic function (here, development tinie D in days) is given by