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

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

Trophic Ecology of Coastal Soft Botoms: A Dive into the Stew of Marine Sediment

00000 WOS:000401091600007International audienceUsing 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

How do food sources drive meiofauna community structure in soft bottom coastal food webs?

International audienceMeiofauna have a strong role in the functioning of coastal ecosystems but how their food sources affect their community structure remains unclear, likely due to the influence of abiotic parameters and the small size of these organisms. The meiofauna and their potential food sources were sampled in several intertidal habitats (i.e., mudflat, seagrass bed, sandflat) of the Marennes-Oléron Bay, France, and the Sylt-Rømø Bight, Germany, to assess the relationships between habitat characteristics and meiofauna community structure. Biomass and quality (carbon/chlorophyll a ratios) of food sources were estimated. Meiofauna community structure based on density and biomass was determined, as well as nematode diversity and feeding types. Meiofauna density and biomass varied highly within habitats and within ecosystems, ranging from 1.7 × 10⁵ to 3.4 × 10⁶ ind. m⁻² and from 0.057 to 1.541 gC m⁻², respectively. Benthic microalgae and sediment organic matter are important drivers in these food webs as the density of two important trophic groups of nematodes, non-selective deposit feeders and epigrowth feeders, varied in accordance with these food sources. No clear relationship was observed between bacterial biomass and selective deposit feeders (i.e., bacterivores) probably due to the high production rate of bacteria. Complementary information about production rates of food source as well as data from trophic markers would provide complimentary information to better understand flows of organic matter in intertidal habitats, particularly for opportunistic species such as non-selective deposit feeders

Trophic importance of microphytobenthos and bacteria to meiofauna in soft-bottom intertidal habitats: A combined trophic marker approach

International audienceMeiofauna can play an important role in the carbon fluxes of soft-bottom coastal habitats. Investigation of their feeding behavior and trophic position remains challenging due to their small size. In this study, we determine and compare the food sources used by nematodes and benthic copepods by using stable isotope compositions, fatty acid profiles and compound specific isotope analyses of fatty acids in the mudflats, seagrass beds and a sandflat of the Marennes-Oléron Bay, France, and the Sylt-Rømø Bight, Germany. Suspended particulate organic matter was much more 13C-depleted than other food sources and meiofauna, highlighting its poor role in the different studied habitats. The very low proportions of vascular plant fatty acid markers in meiofauna demonstrated that these consumers did not rely on this food source, either fresh or detrital, even in seagrass beds. The combined use of stable isotopes and fatty acids emphasized microphytobenthos and benthic bacteria as the major food sources of nematodes and benthic copepods. Compound specific analyses of a bacteria marker confirmed that bacteria mostly used microphytobenthos as a substrate

Quantitative food web modeling unravels the importance of the microphytobenthos-meiofauna pathway for a high trophic transfer by meiofauna in soft-bottom intertidal food webs

Publisher: Elsevier B.V.International audienceMeiofauna are known to have an important role on many ecological processes, although, their role in food web dynamics is often poorly understood, partially as they have been an overlooked and under sampled organism group. Here, we used quantitative food web modeling to evaluate the trophic relationship between meiofauna and their food sources and how meiofauna can mediate the carbon flow to higher trophic levels in five contrasting soft-bottom intertidal habitats (including seagrass beds, mudflats and sandflats). Carbon flow networks were constructed using the linear inverse model-Markov chain Monte Carlo technique, with increased resolution of the meiofauna compartments (i.e. biomass and feeding ecology of the different trophic groups of meiofauna) compared to most previous modeling studies. These models highlighted that the flows between the highly productive microphytobenthos and the meiofauna compartments play an important role in transferring carbon to the higher trophic levels, typically more efficiently so than macrofauna. The pathway from microphytobenthos to meiofauna represented the largest flow in all habitats and resulted in high production of meiofauna independent of habitat. All trophic groups of meiofauna, except for selective deposit feeders, had a very high dependency on microphytobenthos. Selective deposit feeders relied instead on a wider range of food sources, with varying contributions of bacteria, microphytobenthos and sediment organic matter. Ecological network analyses (e.g. cycling, throughput and ascendency) of the modeled systems highlighted the close positive relationship between the food web efficiency and the assimilation of high-quality food sources by primary consumers, e.g. meiofauna and macrofauna. Large proportions of these flows can be attributed to trophic groups of meiofauna. The sensitivity of the network properties to the representation of meiofauna in the models leads to recommending a greater attention in ecological data monitoring and integrating meiofauna into food web models. © 2020 Elsevier B.V