Haemolymph inorganic ion composition of crustaceans from the Southern Ocean

Brachyuran and anomuran decapod crabs do not occur in the extremely cold waters of the Antarctic continental shelf whereas caridean and other shrimp-like decapods, amphipods and isopods are highly abundant. Differing capacities for extracellular ion regulation, especially concerning magnesium, have been hypothesised to determine cold tolerance and by that the biogeography of Antarctic crustaceans. Magnesium is known to have a paralysing effect, which is even more distinct in the cold. As only few or no data exist on haemolymph ionic composition of Sub-Antarctic and Antarctic crustaceans, haemolymph samples of 12 species from these regions were analysed for the concentrations of major inorganic ions (Na+, K+, Ca2+, Mg2+, Cl-, SO4 2-) by ion chromatography. Cation relationships guaranteed neuromuscular excitability in all species. Sulphate and potassium correlated positively with magnesium concentration. The Antarctic caridean decapod as well as the amphipods maintained low (6-20% of ambient sea water magnesium concentration), Sub-Antarctic brachyuran and anomuran crabs as well as the Antarctic isopods high (54-96% of ambient sea water magnesium concentration) haemolymph magnesium levels. In conclusion, magnesium regulation may explain the biogeography of decapods, but not that of the peracarids.

Abundance and of mesozooplanktopn in the Gulf of Lion during MOOGLI 1 and 3 in 1998 and 1999

The MOOGLI dataset contains mesozooplankton data collected in 1998-1999 in the Gulf of Lion (North Western Mediterranean Sea). Zooplankton taxonomy-related abundance per unit volume of the water column.

Seawater carbonate chemistry and biological processes during experiments with calcifiing organisms, 2009

Anthropogenic elevation of atmospheric carbon dioxide (pCO2) is making the oceans more acidic, thereby reducing their degree of saturation with respect to calcium carbonate (CaCO3). There is mounting concern over the impact that future CO2-induced reductions in the CaCO3 saturation state of seawater will have on marine organisms that construct their shells and skeletons from this mineral. Here, we present the results of 60 d laboratory experiments in which we investigated the effects of CO2-induced ocean acidification on calcification in 18 benthic marine organisms. Species were selected to span a broad taxonomic range (crustacea, cnidaria, echinoidea, rhodophyta, chlorophyta, gastropoda, bivalvia, annelida) and included organisms producing aragonite, low-Mg calcite, and high-Mg calcite forms of CaCO3. We show that 10 of the 18 species studied exhibited reduced rates of net calcification and, in some cases, net dissolution under elevated pCO2. However, in seven species, net calcification increased under the intermediate and/or highest levels of pCO2, and one species showed no response at all. These varied responses may reflect differences amongst organisms in their ability to regulate pH at the site of calcification, in the extent to which their outer shell layer is protected by an organic covering, in the solubility of their shell or skeletal mineral, and whether they utilize photosynthesis. Whatever the specific mechanism(s) involved, our results suggest that the impact of elevated atmospheric pCO2 on marine calcification is more varied than previously thought.