(Table 1) Permanent currents in the Campeche Bank area based on data of 24-hour stations

Data of twenty buoy stations were used to compile a new chart of permanent currents in the surface layer (10 m depth) for the region of the Yucatan shelf (Campeche Bank). It was found that vertical variations in direction of the currents are insignificant within the shallow plateau of the banks.

Stable Isotope composition of particulate organic matter and fauna in a deep Mediterranean cold-water coral bank

Cold-water corals (CWC) are frequently reported from deep sites with locally accelerated currents that enhance seabed food particle supply. Moreover, zooplankton likely account for ecologically important prey items, but their contribution to CWC diet remains unquantified. We investigated the benthic food web structure of the recently discovered Santa Maria di Leuca (SML) CWC province (300 to 1100 m depth) located in the oligotrophic northern Ionian Sea. We analyzed stable isotopes (delta13C and delta15N) of the main consumers (including ubiquitous CWC species) exhibiting different feeding strategies, zooplankton, suspended particulate organic matter (POM) and sedimented organic matter (SOM). Zooplankton and POM were collected 3 m above the coral colonies in order to assess their relative contributions to CWC diet. The delta15N of the scleractinians Desmophyllum dianthus, Madrepora oculata and Lophelia pertusa and the gorgonian Paramuricea cf. macrospinawere consistent with a diet mainly composed of zooplankton. The antipatharian Leiopathes glaberrima was more 15N- depletedthan other cnidarians, suggesting a lower contribution of zooplankton to its diet. Our delta13C data clearly indicate that the benthic food web of SML is exclusively fuelled by carbon of phytoplanktonic origin. Nevertheless, consumers feeding at the water sediment interface were more 13C-enriched than consumers feeding above the bottom (i.e. living corals and their epifauna). This pattern suggests that carbon is assimilated via 2 trophic pathways: relatively fresh phytoplanktonic production for 13C-depleted consumers and more decayed organic matter for 13C-enriched consumers. When the delta13C values of consumers were corrected for the influence of lipids (which are significantly 13C-depleted relative to other tissue components), our conclusions remained unchanged, except in the case of L. glaberrima which could assimilate a mixture of zooplankton and resuspended decayed organic matter.

Seawater carbonate chemistry and calcification in the Bahama Bank, 1964-1965

Carbon dioxide is lost from the ocean by calcium carbonate precipitation (-p), photosynthesis (-b) and gas evasion at the sea surface (-g). Among the most active sites are warm shallow seas. In this paper seasonal studies on the Great Bahama Bank relate these processes in an equation which takes into account the indirect effects of advection (a), evaporation (e), and eddy diffusion (d). Calcium carbonate precipitation is very seasonal and accounts for about half of the total losses. The delta sum CO2/deltaCa ratio is always about 1.87 on the bank. A high summer carbonate loss is inversely correlated with summer increases of chlorinity and temperature suggesting that CaCO3 is precipitated inorganically or biogenic production of CaCO3 is regulated by these parameters or both.