Factors influencing the spatio-temporal occurrence of fish eggs and larvae in a northern, physically dynamic coastal environment

Abstract

Distribution patterns, abundance and species composition of the assemblages of fish eggs and larvae in Conception Bay, Newfoundland. Canada. during the early summers of 1990 and 1991 are described. Several species appear to use Conception Bay as a spawning ground. lnterannual and seasonal differences in both species composition and abundance in the bay appear to be associated with differences in environmental conditions, particularly with temperature. Both egg and larval abundances were lower by an order of magnitude in 1991 corresponding to the coldest and less saline waters. Temperature and wind were the environmental factors most associated with the spatial distribution of eggs. In both years, highest abundances of all species were usually found at the head and the eastern side of the bay, corresponding to the warmest waters under dominant westerly winds. On one occasion, greatest abundances and warmer waters were found on the western side of the bay, concomitant with a southerly wind episode. Clustering samples by their relative species composition revealed well-defined assemblages of fish larvae. The variability in relative species composition was strongly associated with the physico-chemical conditions of the surface layer and was consistent with patterns of seasonal successions observed in other ecosystems. We propose that temperature is the principal factor controlling spatio-temporal occurrence of fish eggs and larvae in Conception Bay and, most probably, in coastal waters of Newfoundland and Labrador, Canada. This association may be critical in ecosystems characterized by an extremely short growing season. Conception Bay may play an important role in the early-life history of fish inhabiting the northeast Newfoundland/Labrador shelf. Even if a smaller proportion of fish reproduced in the coastal reglon, their offspring may contribute signiflcantly to the number of individuals recruiting to the population if growth and survival are considerably higher in coastal areas than in offshore areas due to the presence of more favourable habitats for early-life stages of fish.

Larval fish assemblages in coastal waters of central Greece: reflections of topographic and oceanographic heterogeneity

“…temperature, salinity, integrated fluorescence) were calculated for three distinct water column layers (Laprise and Pepin, 1995) (Fig. 2B): The layer immediately below the sea-surface down to the depth where the temperature was 1°C less than that of the surface waters, was defined as the 'surface mixed layer' (SML).…”

Variability in transport of fish eggs and larvae. II. Effects of hydrodynamics on the transport of Downs herring larvae

“…The interaction of spawning site and hydrographic conditions plays an important role in the determination of larval drift or transport (Heath 1989, Laprise & Pepin 1995. Most of the dispersive drift from the spawning grounds of herring stocks in western European waters is in an easterly direction , although other studies have suggested that retention of larvae is important for recruitment success (Iles & Sinclair 1982, Sinclair & Tremblay 1984.…”

Environment and plasticity of myogenesis in teleost fish

“…Adverse environmental conditions in nature can be the cause of significant embryonic mortality (Laprise and Pepin, 1995). Sub-lethal environmental stress impacts on all aspects of development, including myogenesis, with potential consequences for the morphology, physiology, behaviour and survival of the hatched larvae.…”