ABSTRACT
Over thirty species of littoral marine Gammaridea occur along the coasts of the North Atlantic. From one to several species can coexist in a single region. There is an evident, inverse relationship between egg incubation time and temperature (from 14 to >120 days) and consequent trends in the size of the animals on reaching maturity (from 5 mm in warmer waters to 30 mm in the coldest ones) and in lifespan (from <6 months to >5 years). Littoral gammarids are a good example of the shrinking size effect of increasing temperatures and size-related species diversity. In large species, the annual cohorts of the population (3-5 annual size groups) functionally replace the adults of smaller species. The ongoing warming of the European Arctic seas may extend the distribution limits of boreal species so that more Gammarus species may appear on northern coasts hitherto occupied by just one or at most two species.
ABSTRACT
The study aimed to estimate the total oxygen flow through the shallow littoral of the Gulf of Gdansk (southern Baltic Sea). Daily primary production and daily oxygen consumption by meso- and macroplankton and meio- and macrobenthos were measured, as well as the remaining (abiotic/microbial) oxygen consumption of the water column and bottom sediment. The daily gross primary production was 5.0 l of oxygen m(-2), oxygen consumption was 9.2 l m(-2), of which 16% were used by the water column and 84% by the bottom sediment. Abiotic oxygen consumption in water column contributed to less than 5% of the total oxygen consumption, and in the bottom sediment to 67%. Mesoplankton in the water column and meiobenthos in the bottom sediments were the major oxygen consumers in the littoral (67% and 26%, respectively).
