Observations on Diet Composition of Neogobius melanostomus Pallas 1811 (Gobiidae, Pisces) in the Gulf of Gdansk (Baltic Sea)

International audienceThis study documents the diet of Neogobius melanostomus (round goby) from three different habitats within the Gulf of Gdansk. Diet composition of the round goby in the Gulf of Gdansk appears similar to that in its natural environment within the Ponto-Caspian Basin. In its native habitat, the round goby feeds mainly on epibenthic organisms and opportunistically forages on seasonally abundant components of the benthic community. A natural mollusk-feeder, the round goby feeds mainly on the mussel Mytilus trossulus in the Gulf of Gdansk. This food preference most likely is due to the fact that M. trossulus is commonly distributed throughout most of the gulf and dominates the benthic biomass. The adult round goby prefers an environment full of hiding places that also can be used for nests. Thus, submerged stones or concrete structures covered with colonies of M. trossulus are its preferred habitat. Younger gobies are more abundant in the frontal areas of underwater concrete structures where the substrate is characterized by loose stones and the presence of Mya arenaria. These habitats have different faunal structures and, therefore, different trophic relations. The round goby, which is well suited for ecological expansion, has great potential to dominate the majority of the coastal zone of the Baltic Sea. Puck Lagoon, devoid of predatory fish and rich in mussel beds, is an ideal habitat for this gobiid species

Contribution de la méiofaune aux transferts des métaux dans le réseau trophique de la baie de Gdańsk (Baltique) et de la baie de Marennes-Oléron (Atlantique)

Les nématodes (groupe principal de la méiofaune) sont étudiés sous deux aspects: l un, écologique, vise à déterminer la structure taxonomique/trophique du peuplement et évaluer sa contribution au flux de carbone au sein du système benthique dans les Baies de Marennes-Oléron et Gdańsk. Les résultats des expériences de traçage radioactif (14C) ont permis de quantifier le flux de carbone des diatomées benthiques vers les nématodes et confirment l importance des nématodes dans le transfert du C au sein du réseau trophique benthique. L autre, écotoxicologique, s intéresse au compartiment comme réacteur biologique potentiel susceptible d accumuler, biotransformer et transférer les métaux aux maillons supérieurs du réseau trophique. Le compartiment des nématodes aux concentrations de métaux supérieures à celles de la macrofaune constituerait une voie importante de transfert des métaux dans la chaîne alimentaire et jouerait un rôle majeur dans le recyclage des métaux fixés par les diatomées.LA ROCHELLE-BU (173002101) / SudocSudocFranceF

Trophic ecology of coastal soft bottoms: a dive into the stew of marine sediment

Using stable isotope analyses, the present study looked at the fractionation of carbon and nitrogen isotopes between bulk sediment organic matter, particulates from the water column, and benthic consumers from the Northwestern Mediterranean continental shelf. Results showed that sedimentary organic matter in the area under study mainly consisted of phytoplankton detritus. In contrast to their available food source, consumers varied widely both in delta C-13 and delta N-15. Meiofauna fed selectively freshly settled organic particles and channeled energy and matter toward the next upper trophic level. Subsurface primary consumers that feed on less readily digestible sediment organic fractions showed enrichments in rare heavier isotopes as high as those of secondary consumers. Depth of feeding seemed to be a determining factor in their isotope fractionation. Within the sediment, infauna were relying on different food items with different isotope compositions, but metabolic pathways probably explained a great part of their C-13 and N-15 enrichment