%0 Journal Article %J Ecological Indicators %D 2019 %T Changes in marine phytoplankton diversity: Assessment under the Marine Strategy Framework Directive %A Rombouts, I. %A Nathalie Simon %A Anais Aubert %A T. Cariou %A Eric Feunteun %A Laurent Guerin %A M. Hoebeke %A A. McQuatters-Gollop %A F. Rigaut-Jalabert %A Luis Felipe Artigas %K community composition %K Good environmental status %K Indicators %K Marine policy %K MSFD %K OSPAR %K Pelagic habitat %K Plankton %X The Marine Strategy Framework Directive requires EU Member States to assess the Good Environmental Status (GES) of their marine waters in a coherent and strategic manner. For the regional assessment of biodiversity, the OSPAR Intersessional Coordination Group of Biodiversity Assessment and Monitoring (ICG-COBAM) provides substantial advice. Through expert working groups, phytoplankton indicators are currently being developed to measure the state and the change in pelagic diversity, to quantify food web dynamics and to measure the extent of eutrophication impacts. We developed a multi-metric indicator that is compliant with the common OSPAR indicator “Changes in plankton diversity” (PH3). The aim was to describe the structure of the phytoplankton community (alpha diversity) and to detect significant temporal changes (beta diversity) to evaluate the health of pelagic habitats. In this pilot study, we used three coastal time-series in the Western Channel and the north of the Bay of Biscay (North Atlantic, France) to test the efficiency and the performance of several existing diversity indices. We validated two alpha diversity indices, namely the Menhinick Index (D) and the Hulburt Index (δ), based on their complementary ecological information, their strong relationship with habitat characteristics, and their relative ease of interpretation for stakeholders. Temporal shifts or rate of change in community structure were detected by the Local Contributions to Beta Diversity index (LCBD; a beta diversity measure). For the years where significantly high LCBD values were found, the Importance Value Index (IVI) was calculated to potentially identify the taxa (genus) responsible for the “unusual” community structure. For example, at the Ouest Loscolo site in 2008, an elevated LCBD (0.45) coincided with a high dominance value (Hulburt’s Index) caused by the occurrence of a monospecific bloom of Leptocylindrus spp. (IVI = 73%) in July (2.22 × 106 cells L−1) and October (8 × 106 cells L−1). In this way, PH3 informs on different aspects of phytoplankton diversity from a community to a genus level. At the current stage of development, however, PH3 acts as a “surveillance” rather than an operational indicator since the relationship to GES is not directly tracked. In the future, by additional testing of PH3 and extending the geographical scope, the robustness of the assessment could be further determined across the OSPAR Maritime Area. %B Ecological Indicators %V 102 %P 265 - 277 %G eng %U http://www.sciencedirect.com/science/article/pii/S1470160X19301190 %R https://doi.org/10.1016/j.ecolind.2019.02.009 %0 Journal Article %J Ecological Indicators %D 2019 %T A new type of plankton food web functioning in coastal waters revealed by coupling Monte Carlo Markov chain linear inverse method and ecological network analysis %A Meddeb, M. %A Nathalie Niquil %A Grami, B. %A Mejri, K. %A Haraldsson, M. %A Chaalali, A. %A Pringault, O. %A Hlaili, A.S. %K Bacteria (microorganisms) %K bacterium %K Carbon %K Chemical contamination %K coastal water %K Coastal waters %K ecological modeling %K Ecology %K ecosystem function %K Ecosystems %K Electric network analysis %K Food microbiology %K food web %K Food web model %K Food webs %K inverse analysis %K Inverse problems %K Markov chain %K Markov processes %K Mediterranean sea %K Monte Carlo analysis %K Monte Carlo methods %K net primary production %K network analysis %K Phytoplankton %K picoplankton %K Plankton %K Protozoa %K protozoan %K Seasonal variation %K trophic status %K Trophic structure %X Plankton food webs (PFW) typology is based on different categories of functioning, according to the dominant processes and the role played by heterotrophic bacteria, small vs large phytoplankton, and small vs large zooplankton. Investigating the structure and the function of planktonic food webs in two SW Mediterranean waters (inshore and marine sites) at four seasons, using inverse (LIM-MCMC) and ecological network (ENA) analyses, we identified a new type of food web, called the “bacterial multivorous food web”. This food web adds to the conventional trophic continuum as previously reported. The “bacterial multivorous food web” present in winter showed the lowest primary production among seasons, but highest bacterial production. Several food web ratios characterized this new typology e.g. picophytoplankton net primary production to total primary production varied from 0.20 to 0.28; bacterial to primary production ratio is higher than values reported in global scale (≅1); bacterial net production to the potential protozoan prey net production was high (>0.2). In this special food web, carbon was mostly recycled, with a moderate fraction channeled to deep waters, which lead to a higher retention of carbon inside the ecosystem. This winter PFW also seemed to be the most organized, specialized, stable and mature, as related to common interpretations of ENA. The spring was characterized by herbivorous food web, with highest activity coinciding with low stability. Although less usual, the herbivorous pathway was also observed during summer, in inshore waters. The autumn food webs, which functioned as multivorous or microbial food webs, appeared to be stable and mature. Finally, our study demonstrates the usefulness of food web models derived ratios combined with ecological network analysis indices to conduct evaluation of the structure and functioning of ecosystems and potentially to support management decisions in marine environment. © 2019 %B Ecological Indicators %I Elsevier B.V. %V 104 %P 67-85 %G eng %U https://www.sciencedirect.com/science/article/abs/pii/S1470160X19303243 %R 10.1016/j.ecolind.2019.04.077 %0 Journal Article %J Progress in Oceanography %D 2018 %T Plankton food-web functioning in anthropogenically impacted coastal waters (SW Mediterranean Sea): An ecological network analysis %A Meddeb, M. %A Grami, B. %A Chaalali, A. %A Haraldsson, M. %A Nathalie Niquil %A Pringault, O. %A Sakka Hlaili, A. %K Algae %K anthropogenic effect %K Anthropogenic impacts %K Anthropogenic pressures %K Bizerte %K Bizerte Bay %K Chemical analysis %K Chemical contamination %K coastal water %K community structure %K Ecological network analysis %K Ecology %K ecosystem function %K ecosystem modeling %K Ecosystems %K eutrophication %K food web %K Food webs %K Functional properties %K Inverse problems %K Lakes %K Linear inverse models %K Markov processes %K Mediterranean coastal waters %K Mediterranean ecosystem %K Mediterranean sea %K Monte Carlo methods %K network analysis %K Phytoplankton %K Plankton %K primary production %K Tunisia %K Zooplankton %X The study is the first attempt to (i) model spring food webs in three SW Mediterranean ecosystems which are under different anthropogenic pressures and (ii) to project the consequence of this stress on their function. Linear inverse models were built using the Monte Carlo method coupled with Markov Chains to characterize the food-web status of the Lagoon, the Channel (inshore waters under high eutrophication and chemical contamination) and the Bay of Bizerte (offshore waters under less anthropogenic pressure). Ecological network analysis was used for the description of structural and functional properties of each food web and for inter-ecosystem comparisons. Our results showed that more carbon was produced by phytoplankton in the inshore waters (966–1234 mg C m−2 d−1) compared to the Bay (727 mg C m−2 d−1). The total ecosystem carbon inputs into the three food webs was supported by high primary production, which was mainly due to >10 µm algae. However, the three carbon pathways were characterized by low detritivory and a high herbivory which was mainly assigned to protozooplankton. This latter was efficient in channelling biogenic carbon. In the Lagoon and the Channel, foods webs acted almost as a multivorous structure with a tendency towards herbivorous one, whereas in the Bay the herbivorous pathway was more dominant. Ecological indices revealed that the Lagoon and the Channel food webs/systems had high total system throughput and thus were more active than the Bay. The Bay food web, which had a high relative ascendency value, was more organized and specialized. This inter–ecosystem difference could be due to the varying levels of anthropogenic impact among sites. Indeed, the low value of Finn's cycling index indicated that the three systems are disturbed, but the Lagoon and the Channel, with low average path lengths, appeared to be more stressed, as both sites have undergone higher chemical pollution and nutrient loading. This study shows that ecosystem models combined with ecological indices provide a powerful approach to detect change in environmental status and anthropogenic impacts. © 2018 %B Progress in Oceanography %I Elsevier Ltd %V 162 %P 66-82 %G eng %U https://www.sciencedirect.com/science/article/abs/pii/S0079661117300782 %R 10.1016/j.pocean.2018.02.013