Abundance of mesozooplankton in the Alboran Sea during Almofront-2

The ALMOFRONT2 dataset contains mesozooplankton data collected in 1997 – 1998 in the Alboran Sea (South Western Mediterranean Sea) between : 37° 00' N, 2° 54' W and 35° 18' N, 0°00' E

Dynamique et nutrition du zooplancton en milieu lagunaire macrotidal (Bassin d'Arcachon) (Flux de carbone et d'azote associés, conséquences sur le pool nutritif et sur les organismes)

AIX-MARSEILLE2-BU Sci.Luminy (130552106) / SudocBORDEAUX1-Lab.Océanogr.Arcacho (330092101) / SudocBANYULS/MER-Observ.Océanol. (660162201) / SudocPLOUZANE-Bibl.La Pérouse (290195209) / SudocSudocFranceF

The feeding ecology of the copepod Centropages typicus (Kröyer)

Special issue The Biology and Ecology of Centropages typicus.-- 14 pages, 4 figures, 2 tablesHere we report on the current knowledge on the feeding ecology of the planktonic copepod Centropages typicus. We describe the foraging process of C. typicus from the detection of prey to their digestion, considering also the effects of several physical variables on the feeding activity of the species. C. typicus is an omnivorous copepod that feeds on a wide spectrum of prey, from small algae (3–4 μm equivalent spherical diameter, ESD) to yolk-sac fish larvae (3.2–3.6 mm length). It uses both suspensivorous and ambush feeding strategies, depending on the characteristics of the prey. In general, C. typicus exhibits selection for large motile prey, such as ciliates or dinoflagellates, both in nature and laboratory, and this selective pattern is enhanced under moderate intensities of turbulence. Daily rations in the field are somewhat lower than those found in the laboratory, which indicates food limitation. This fact, together with the relatively modest capacity of the species to adapt to fluctuations in food availability may explain the geographical distribution of C. typicus, being restricted to near-shelf waters. In general, it does not seem that C. typicus feeding severely impacts planktonic populations. However, the occasional importance of the species in certain ecosystems is also apparentThis work was supported by Grant CTM2004-02575/MAR and program Ramón y Cajal from the Ministry of Education and Science of Spain to A.C. and by the “Programme National Environnement Côtier of France” to F.C. and R.G.Peer reviewe

Carbon fluxes from the microbial food web to mesozooplankton. An approach in the surface layer of a pelagic area (NW Mediterranean Sea)

International audienceThe microbial food web structure, the carbon flux between mesozooplankton and the microbial community, and the importance of heterotrophs in the diet of marine zooplankton were investigated in the surface layer of a pelagie area of the NW Mediterranean Sea in five 24-h shipboard experiments. Heterotrophic flagellates grazed 65 % to 91 % of the bacterial production. However, the protozoan community seems also to utilize alternative carbon sources, such as small autotrophs. In most of the experiments, the estimated production of the protozoan > 7 ~ was sufficient to supply mesozooplankton carbon demand. Copepods stimulated bacterial growth, presumably through excretion and preference for heterotrophic flagellates. Variations of the experimentally estimated metabolic 0/N ratio (oxygen consumption through respiration, relative to nitrogen excretion) indicated that the mesozooplankton nutrition varied with the type of food web found on each occasion. Mesozooplankton directly interacted with the microbial food web by grazing upon heterotrophic protozoa, especially when small phytoplankton dominated the autotrophic community or under oligotrophic conditions

Variations pondérales, structurales et physiologiques du zooplancton en relation avec différents types de structures (upwelling marocain (région d'Agadir), front Alméria-Oran (ouest de la mer d'Alboran), Courant Nord Méditerranéen et zone de dilution rhodanienne (Golfe du Lion))

AIX-MARSEILLE2-BU Sci.Luminy (130552106) / SudocAIX-MARSEILLE2-Stat.Mar. Endoume (130552206) / SudocSudocFranceF

Elemental composition, biochemical composition and caloric value of Antarctic krill. Implications in Energetics and carbon balances

Samples of Antarctic krill were analyzed for elemental composition, biochemical composition, weight and caloric content. Sexes and maturity stages were separated. Mature females showed the highest caloric values (joules) and juveniles the lowest in a per animal basis. On unit of wet weight per animal basis, spent females showed the lowest caloric values. For the caloric values by animal, a significant difference was found between males, mature females, spent females and juveniles, either on a per animal basis or in the basis of 1 g of wet weight, showing a real difference between the groups, regardless of their individual size. Significant differences were found for carbon, nitrogen and lipids, but not for proteins, analyzed in % of dry weight. Carbon was lowest for spent females and highest for mature females. On the contrary, nitrogen values were lowest for mature females and highest for males. Mature females had the highest lipid content and males the lowest. All variables were significantly correlated. For the linear regression analysis, the best correlation found was between joules and carbon, followed by carbon vs. dry weight and joules vs. dry weight. In an analysis with two independent variables, the best correlation was found for joules vs. lipids and dry weight, followed by joules vs. carbon and nitrogen, and joules vs. lipids and proteins. The results obtained were used to make an analysis of the energy and carbon fluxes through the food chain in the sampled area, showing higher energetic and carbon ``densities'' in frontal areas, the POM calorific values showed an opposite pattern than that of krill. (C) 2009 Elsevier B.V. All rights reserved

Biomass, metabolism and nutrition of zooplankton in the Gulf of Lions (NW Mediterranean)

International audienc

Food web structure variability in the surface layer, at a fixed station influenced by the North Western Mediterranean Current

International audienceThe structure of the planktonic community and the influence of mesozooplankton migration on the microbial food web were investigated during six die' studies from June 92 to June 93 in the surface waters of a station in the NorthWestern Mediterranean Sea. Each die' study consisted of sampling at 5 and 40 m every 3 h over 24 h. Most of the times diel cycles did not show any convincing diel patterns in any of the variables studied. Clear zooplankton migration was evident in only two diel studies. The ratio of heterotrophic/autotrophic biomasses varied from 0 .68 to 3 .0, with a strong dominance of the heterotrophic biomass under oligotrophic conditions. Differences in food web structure were probably related to the influences of coastal water and the NorthWestern Mediterranean Current. Thus we found that the planktonic food web variability relatable to hydrodynamic variability, to be greater than die' variability. However, very large differences in food web structure among dates were evident. For example proportion of Chl a found in the < 10 tm fraction varied from 18 to 96%