Comparative life-histories, population dynamics and productivity of Schistomysis populations (Crustacea, Mysida) in European shelf environments

• Abundance fluctuations during an annual cycle were interpreted according to environmental data.
• Brood size and intramarsupial mortality were estimated from examination of marsupial content of brooding females.
• Individual longevity and voltinism were appreciated from analysis of demographic data.
• Annual secondary production was calculated using size-frequency and empirical methods.

A biological study of suprabenthic mysids of genus Schistomysis (Crustacea, Mysida, Mysidae) was carried out based on quantitative samples collected in coastal waters of the SE Bay of Biscay (NE Atlantic) and the Catalan Sea (W Mediterranean). Aspects of the ecology of species noted during this study are summarized and the results of previous researches are incorporated. Small and large-scale environmental factors (swash and surf climate, depth, temperature, day–night and seasonal cycles) contributed significantly to population distributions. All Schistomysis   populations are characterized by faster individual growth and earlier maturity at higher temperature, resulting in intensive recruitment during spring or summer seasons in combination with higher fecundity of genitors. Regarding productivity, our production and P/B¯ estimates ranged between 2255–26,321 mg AFDW/100 m3/year and 6.09–9.73, respectively. These production values are similar to those found for comparable marine mysids with two or three generations per year. The observed demographic heterogeneity and production of populations has ecological implications in the Bay of Biscay and Mediterranean areas, where Schistomysis species are dominant components of littoral and shelf suprabenthic communities.