%0 Book Section %B Sales bêtes, mauvaises herbes %D 2018 %T De la nuisibilité à la patrimonialité en milieu marin. L'histoire d'une ambiguïté entretenue %A Patrick, Le Mao %A Nicolas Desroy %A Jérôme Fournier %A Laurent Godet %A Eric Thiébaut %B Sales bêtes, mauvaises herbes %I Presses Universitaires de Rennes %C Rennes %V 1 %G eng %6 1 %0 Journal Article %J Estuarine, Coastal and Shelf Science %D 2018 %T Distribution, associated species and extent of biofouling “reefs” formed by the alien species Ficopomatus enigmaticus (Annelida, Polychaeta) in marinas %A Maud Charles %A Robin Faillettaz %A Nicolas Desroy %A Jérôme Fournier %A Katherine Costil %K Alien species %K Benthic communities %K Biofouling %K Ficopomatus enigmaticus %K Marinas %K Normandy %X
Artificial structures in ports are commonly colonized by non-indigenous epifauna that tolerate high pollution levels. Bioconstructions built by alien species may offer sheltered microhabitats for motile (vagile) animals but biofouling often becomes detrimental to human activities. In this context, the present study provides an inventory of 1) the extent of biofouling related to the alien Polychaeta Ficopomatus enigmaticus on hard structures of marinas in Normandy, France, and 2) the biodiversity of sessile (attached) or vagile (motile) fauna associated with these “reefs”, including both native and alien species. Reefs built by F. enigmaticus were found in 6 out of 12 marinas with oligohaline-mesohaline waters. Significant differences in the total volume of biofouling were found among sites, with maximum values observed in Honfleur's old basin (459.52 mL per 0.04 m2). Ficopomatus enigmaticus greatly dominated the sessile invertebrate community both in volume (74–100%) and weight (70–100%) in 5 out of 6 marinas. The fouling formed by 5 alien species was colonized by 15 motile invertebrate taxa, including 3 cryptogenic or alien species. The alien crab Rhithropanopeus harrisi displayed the highest frequency of occurrence (>80%) and mean density (>300 ind m−2), and the global densities of sessile (except F. enigmaticus) and motile fauna were significantly correlated (r = 0.824; p < 0.05). While motile fauna density was also significantly correlated with the biovolume of B. improvisus and M. leucophaeata, it was not with F. enigmaticus (r = 0.421; p > 0.05). In line with previous studies, these results suggest that F. enigmaticus acts as an engineer offering shelter for reef-associated organisms. In addition, results suggest that at the regional scale, inter-site differences in motile fauna may reflect differences in environmental parameters such as salinity. The presence of F. enigmaticus at low salinity levels led to assess its potential distribution at the scale of the European coasts, suggesting that in the context of climate change, favorable conditions for spawning (>18 °C) will likely expand towards the North, and particularly in the eastern and northern Baltic Sea.
%B Estuarine, Coastal and Shelf Science %G eng %R https://doi.org/10.1016/j.ecss.2018.07.007 %0 Journal Article %J Estuarine, Coastal and Shelf Science %D 2018 %T Interplay between abiotic factors and species assemblages mediated by the ecosystem engineer Sabellaria alveolata (Annelida: Polychaeta) %A Auriane Jones %A Stanislas Dubois %A Nicolas Desroy %A Jérôme Fournier %XSabellaria alveolata is a gregarious polychaete that uses sand particles to build three-dimensional structures known as reefs, fixed atop rocks or built on soft sediments. These structures are known to modify the local grain-size distribution and to host a highly diversified macrofauna, altered when the reef undergoes disturbances.
The goal of this study was to investigate the different sedimentary and biological changes associated with the presence of a S. alveolata reef over two contrasting seasons (late winter and late summer), and how these changes were linked. Three different sediments were considered: the engineered sediment (the actual reef), the associated sediment (the soft sediment surrounding the reef structures) and a control soft sediment (i.e. no reef structures in close proximity). Univariate and multivariate comparisons of grain-size distribution, soft sediment characteristics (organic matter content, chlorophyll a, pheopigments and carbohydrate concentrations) and macrofauna were conducted between the different sediment types at both seasons and between the two seasons for each sediment type. A distance-based redundancy analyses (dbRDA) was used to investigate the link between the different environmental parameters and the macrofauna assemblages. Finally, we focused on a disturbance continuum of the engineered sediments proxied by an increase in the mud present in these sediments. The effects of a continuous and increasing disturbance on the associated fauna were investigated using pairwise beta diversity indices (Sørensen and Bray-Curtis dissimilarities and their decomposition into turnover and nestedness). Results showed a significant effect of the reef on the local sediment distribution (coarser sediments compared to the control) and on the benthic primary production (higher in the associated sediments). At both seasons, S. alveolata biomass and sediment principal mode were the environmental parameters which best differentiated the engineered, associated and control sediment assemblages. These two parameters are under the ecosystem engineer's influence stressing its importance in structuring benthic macrofauna. Furthermore, in late summer but not in late winter, presence/absence and abundance based beta diversity were positively correlated to our disturbance proxy (mud content) a tendency driven by a species replacement and a rise in the associated fauna density.
Our first set of results highlight the importance of S. alveolata reefs as benthic primary production enhancers via their physical structure and their biological activity. The results obtained using beta diversity indices emphasize the importance of recruitment in structuring the reef's macrofauna and – paradoxically – the ecological value of S. alveolata degraded forms as biodiversity and recruitment promoters.
Seagrass meadows form highly productive and valuable ecosystems in the marine environment. Throughout the year, seagrass meadows are exposed to abiotic and biotic variations linked to (i) seasonal fluctuations, (ii) short-term stress events such as, e.g., local nutrient enrichment, and (iii) small-scale disturbances such as, e.g., biomass removal by grazing. We hypothesized that short-term stress events and smallscale disturbances may affect seagrass chance for survival in temperate latitudes. To test this hypothesis we focused on seagrass carbon reserves in the form of starch stored seasonally in rhizomes, as these have been defined as a good indicator for winter survival. Twelve Zostera noltei meadows were monitored along a latitudinal
gradient in Western Europe to firstly assess the seasonal change of their rhizomal starch content. Secondly, we tested the effects of nutrient enrichment and/or biomass removal on the corresponding starch content by using a short-term manipulative field experiment at a single latitude in the Netherlands. At the end of the growing season, we observed a weak but significant linear increase of starch content along the latitudinal gradient from south to north. This agrees with the contention that such reserves are essential for regrowth after winter, which is more severe in the north. In addition, we also observed a weak but significant positive relationship between starch content at the beginning of the growing season and past winter temperatures. This implies a lower regrowth potential after severe winters, due to diminished starch content at the beginning of the growing season. Short-term stress and disturbances
may intensify these patterns, because our manipulative experiments show that when nutrient enrichment and biomass loss co-occurred at the end of the growing season, Z. noltei starch content declined. In temperate zones, the capacity of seagrasses to accumulate carbon reserves is expected to determine carbon-based regrowth after winter. Therefore, processes affecting those reserves might affect seagrass resilience. With increasing human pressure on coastal systems, short- and small-scale stress events are expected to become more frequent, threatening the resilience of seagrass ecosystems, particularly at higher latitudes, where populations tend to have an annual cycle highly dependent on their storage capacity.
Species ranges are shifting globally to track temperature changes in response to climate warming, with substantial variability among taxa. In
the English Channel, a biogeographical transition zone between the cold temperate and warm temperate provinces of the North-East Atlantic, distribution shifts have been relatively well documented for plankton, fish and intertidal benthic organisms, but little information is available on sublittoral benthos. Following a description of the magnitude of the sea bottom temperature (SBT) rise, the changes in the distribution and occupancy of 65 benthic invertebrate species were analysed by comparing data collected throughout the English Channel at more
than 200 stations sampled during a cool period in the 1960s–1970s and at present in 2012–2014. A non-uniform rise in SBT for the last three
decades was observed at the regional scale, varying from 0.07 to 0.54C per decade. This rise differs from that reported for sea surface temperature
(SST) in stratified areas suggesting that SBT should be used rather than SST to analyse responses of subtidal organisms to climate change. Despite shifts in both minimum and maximum sea bottom isotherms (2.5 and 3.2 km.year1, respectively), the distribution centroid shift of most species remained <1.0 km.year1, regardless of the average temperatures they usually experience. Conversely, decreases were observed in the occurrence of most cold-water species and increases were found in the occurrence of most warm-water species. These results suggest that ongoing climate change could lead to a decrease in benthic biodiversity at range limits, especially where connection routes are lacking for new migrants.
This study aims to describe the patterns of soft bottom macrozoobenthic richness along French coasts. It is based on a collaborative database developed by the “Réseau des Stations et Observatoires Marins” (RESOMAR). We investigated patterns of species richness in sublittoral soft bottom habitats (EUNIS level 3) at two different spatial scales: 1) seaboards: English Channel, Bay of Biscay and Mediterranean Sea and 2) 0.5° latitudinal and longitudinal grid. Total observed richness, rarefaction curves and three incidence-based richness estimators (Chao2, ICE and Jacknife1) were used to compare soft bottom habitats species richness in each seaboard. Overall, the Mediterranean Sea has the highest richness and despite higher sampling effort, the English Channel hosts the lowest number of species. The distribution of species occurrence within and between seaboards was assessed for each major phylum using constrained rarefaction curves. The Mediterranean Sea hosts the highest number of exclusive species. In pairwise comparisons, it also shares a lower proportion of taxa with the Bay of Biscay (34.1%) or the English Channel (27.6%) than that shared between these two seaboards (49.7%). Latitudinal species richness patterns along the Atlantic and English Channel coasts were investigated for each major phylum using partial LOESS regression controlling for sampling effort. This showed the existence of a bell-shaped latitudinal pattern, highlighting Brittany as a hotspot for macrobenthic richness at the confluence of two biogeographic provinces.
%B Journal of Sea Research %V 130 %P 96 - 106 %G eng %U http://www.sciencedirect.com/science/article/pii/S1385110116302660 %R https://doi.org/10.1016/j.seares.2017.03.011 %0 Journal Article %J Limnology and Oceanography %D 2017 %T Seasonal and latitudinal variation in seagrass mechanical traits across Europe: The influence of local nutrient status and morphometric plasticity %A L.M. Soissons %A M.M. van Katwijk %A G. Peralta %A F.G. Brun %A P.G. Cardoso %A T.F. Grilo %A B. Ondiviela %A M. Recio %A M. Valle %A J.M. Garmendia %A F. Ganthy %A I. Auby %A L. Rigouin %A Laurent Godet %A Jérôme Fournier %A Nicolas Desroy %A L. Barillé %A P. Kadel %A R. Asmus %A P.M.J. Herman %A T.J. Bouma %XSeagrasses are marine flowering plants distributed worldwide. They are however threatened, mostly due to the increase of human activities. Seagrasses have the capacity to adapt their morphological, physiological, and mechanical traits to their local conditions. Mechanical traits have been identified as a good tool to investigate a plant-species capacity to withstand physical forces or disturbances but are still sparsely studied in seagrasses. With this study, we aimed to assess how the mechanical traits of a broadly spread seagrass species vary along a latitudinal gradient in relation to its morphometric plasticity and nutrient status. We found that seagrasses acclimate their mechanical traits in relation to their physiological or morphological traits, both over the growing season and across a latitudinal range: leaves were weaker and thinner in northern areas, particularly at the end of the growing season. Besides the influence of the latitudinal gradient, leaf mechanical strength and stiffness were both strongly affected by their morphometric plasticity. Moreover, we showed that leaves mechanical traits change depending on their nutrient status: leaves were stronger and stiffer in oligotrophic conditions as compared to more eutrophic conditions. Thus, our results imply that, under eutrophication, leaves become weaker and thus more vulnerable to physical forces. This vulnerability is higher in the north at the end of the growing season. The latter is consistent with the more ephemeral character of northern seagrass meadows, in contrast to the more evergreen southern meadows.
%B Limnology and Oceanography %G eng %U http://onlinelibrary.wiley.com/doi/10.1002/lno.10611/full %R 10.1002/lno.10611 %0 Journal Article %J Estuarine, Coastal and Shelf Science %D 2016 %T How do macrobenthic resources concentrate foraging waders in large megatidal sandflats? %A Ponsero, Alain %A Sturbois, Anthony %A Nicolas Desroy %A Patrick Le Mao %A Jones, Auriane %A Jérôme Fournier %XThe relationship between foraging shorebirds, macrobenthos and sedimentary parameters has been widely studied across Western Europe. Megatidal areas have large zones uncovered when the water retreats. Consequently, in such cases, the tide also influences foraging activities. This paper examines the use of an intertidal space by waders to define how macrobenthic resource concentrates foraging activity of birds in a large megatidal sandflat. This approach combines accurate spatial distribution of waders (Oystercatcher, Eurasian curlew, Bar-tailed Godwit and Redknot) according to their activity with ecological/biological parameters. A differential exploitation of the flat is clearly shown, with macrobenthic biomass appearing as one of the main explanatory factor for the four species considered on the western part of the bay and altitude (shore elevation) in the eastern part. The novelty of this study relates to the large area, also presumed to be a functional unit, while considering at the same time the singularities of the different parts of the flat. This multi-scale approach identifies important factors influencing the differential distribution patterns observed. The different selected parameters present an important variability in their contribution, underlining the complexity of explaining the distribution of foraging birds. Consequently, the study of such complex phenomena needs to consider additional variables to improve the relevance of explanatory models.
%B Estuarine, Coastal and Shelf Science %G eng %R 10.1016/j.ecss.2016.05.023 %0 Journal Article %J Oecologia %D 2016 %T Pollen limitation may be a common Allee effect in marine hydrophilous plants: implications for decline and recovery in seagrasses %A B.I. Van Tussenbroek %A L.M. Soissons %A T.J. Bouma %A R. Asmus %A I. Auby %A F.G. Brun %A P.G. Cardoso %A Nicolas Desroy %A Jérôme Fournier %A F. Ganthy %A J.M. Garmendia %A Laurent Godet %A T.F. Grilo %A P. Kadel %A B. Ondiviela %A G. Peralta %A M. Recio %A M. Valle %A T. Van der Heide %A van Katwijk, M M %B Oecologia %P 1-15 %G eng %R 10.1007/s00442-016-3665-7 %0 Journal Article %J Estuarine, Coastal and Shelf Science %D 2015 %T Biogenic reefs affect multiple components of intertidal soft-bottom benthic assemblages: the Lanice conchilega case study %A De Smet, Bart %A D'Hondt, An Sophie %A Pieterjan, Verhelst %A Jérôme Fournier %A Laurent Godet %A Nicolas Desroy %A Rabaut, Marijn %A Magda, Vincx %A Jan, Vanaverbeke %K beaches %K benthos %K biogenic reefs %K community composition %K Lanice conchilega %K tidal flats %XBiogenic reefs composed of the tube-building polychaete Lanice conchilega are important from a conservation point of view because they noticeably increase the biodiversity in otherwise species poor
environments. However, up to now, little or no attention has been paid to the intertidal epi- and hyperbenthic communities associated with the reefs. Therefore, this is the first study which focuses on
the effect of L. conchilega reefs on the entire bentho-pelagic community at two different locations. Environmental variables were measured and macro-, epi- and hyperbenthic communities were sampled
within a L. conchilega reef and a control area at two locations in France: the bay of the Mont Saint-Michel (BMSM) and Boulogne-sur-Mer (Boulogne). The effect of the reef presence on the benthic community
was studied with a 3-factor (Reef, Location and Period) Permanova. In addition, the relationship between the benthic community and the environmental variables was investigated using Distance-based linear
models (DistLM). Most collected organisms were sampled in the reef area (macrobenthos: 91%, epibenthos: 81% and hyperbenthos: 78.5%) indicating that, independent of the location, the L. conchilega
reefs positively affect all three associated benthic communities. However, the extent of the effect seems to be most pronounced for the macrobenthos and less distinct in case of the hyperbenthos. The macro-,
and epibenthos are mainly structured by biotic variables (L. conchilega density and macrobenthic food availability respectively), while the hyperbenthos is rather structured by environmental variables. In
general, L. conchilega reefs do not only affect abundances and diversity but they substantially steer the structure of the intertidal benthic sandy beach ecosystem.
Based on a parallel sampling conducted during autumn 2008, a comparative study of the intertidal benthic macrofauna among 10 estuarine systems located along the Channel and Atlantic coasts of France was performed in order to assess the level of fauna similarity among these sites and to identify possible environmental factors involved in the observed pattern at both large (among sites) and smaller (benthic assemblages) scales. More precisely this study focused on unraveling the observed pattern of intertidal benthic fauna composition and diversity observed at among-site scale by exploring both biotic and abiotic factors acting at the among- and within-site scales. Results showed a limited level of similarity at the among-site level in terms of intertidal benthic fauna composition and diversity. The observed pattern did not fit with existing transitional water classification methods based on fish or benthic assemblages developed in the frame of the European Water Framework Directive (WFD). More particularly, the coastal plain estuaries displayed higher among-site similarity compared to ria systems. These coastal plain estuaries were characterized by higher influence of river discharge, lower communication with the ocean and high suspended particulate matter levels. On the other hand, the ria-type systems were more dissimilar and different from the coastal plain estuaries. The level of similarity among estuaries was mainly linked to the relative extent of the intertidal “Scrobicularia plana–Cerastoderma edule” and “Tellina tenuis” or “Venus” communities as a possible consequence of salinity regime, suspended matter concentrations and fine particles supply with consequences on the trophic functioning, structure and organization of benthic fauna. Despite biogeographical patterns, the results also suggest that, in the context of the WFD, these estuaries should only be compared on the basis of the most common intertidal habitat occurring throughout all estuarine systems and that the \{EUNIS\} biotope classification might be used for this purpose. In addition, an original inverse relation between γ-diversity and area was shown; however, its relevance might be questioned.
%B Journal of Sea Research %V 90 %P 95 - 110 %8 07/2014 %G eng %U http://www.sciencedirect.com/science/article/pii/S1385110114000495 %R http://dx.doi.org/10.1016/j.seares.2014.02.014