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De Wit, R., Rey-Valette, H., Balavoine, J., Ouisse, V., & Lifran, R. (2017). Restoration ecology of coastal lagoons: new methods for the prediction of ecological trajectories and economic valuation. Aquatic Conserv: Mar. Freshw. Ecosyst., 27(1), 137–157.
Résumé: * Conservation of the seven lagoons of the Palavas complex (southern France) has been severely impaired by nutrient over-enrichment during at least four decades. The effluents of the Montpellier wastewater treatment plant (WWTP) represented the main nutrient input. To improve the water quality of these lagoons, this WWTP was renovated and upgraded and, since the end of 2005, its effluents have been discharged 11 km offshore into the Mediterranean (total investment €150 M). * Possibilities of ecosystem restoration as part of a conservation programme were explored by a focus group of experts. Their tasks were: (i) to evaluate the impact of the reduction of the nutrient input; (ii) if necessary, to design additional measures for an active restoration programme; and (iii) to predict ecosystem trajectories for the different cases. Extension of Magnoliophyta meadows can be taken as a proxy for ecosystem restoration as they favour the increase of several fish (seahorse) and bird (ducks, swans, herons) species, albeit they represent a trade-off for greater flamingos. Additional measures for active ecosystem restoration were only recommended for the most impaired lagoon Méjean, while the least impaired lagoon Ingril is already on a trajectory of spontaneous recovery. * A multiple contingent valuation considering four different management options for the Méjean lagoon was used in a pilot study based on face-to-face interviews with 159 respondents. Three levels of ecosystem restoration were expressed in terms of recovery of Magnoliophyta meadows, including their impact on emblematic fish and avifauna. These were combined with different options for access (status quo, increasing access, increasing access with measures to reduce disturbance). The results show a willingness of local populations to pay per year about €25 for the highest level of ecological restoration, while they were only willing to allocate about €5 for additional footpaths and hides.
Copyright © 2015 John Wiley & Sons, Ltd. |
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Giakoumi, S., Halpern, B. S., Michel, L. N., Gobert, S., Sini, M., Boudouresque, C. - F., et al. (2015). Towards a framework for assessment and management of cumulative human impacts on marine food webs. Conservation Biology, 29(4), 1228–1234.
Résumé: Effective ecosystem-based management requires understanding ecosystem responses to multiple human threats, rather than focusing on single threats. To understand ecosystem responses to anthropogenic threats holistically, it is necessary to know how threats affect different components within ecosystems and ultimately alter ecosystem functioning. We used a case study of a Mediterranean seagrass (Posidonia oceanica) food web and expert knowledge elicitation in an application of the initial steps of a framework for assessment of cumulative human impacts on food webs. We produced a conceptual seagrass food web model, determined the main trophic relationships, identified the main threats to the food web components, and assessed the components’ vulnerability to those threats. Some threats had high (e.g., coastal infrastructure) or low impacts (e.g., agricultural runoff) on all food web components, whereas others (e.g., introduced carnivores) had very different impacts on each component. Partitioning the ecosystem into its components enabled us to identify threats previously overlooked and to reevaluate the importance of threats commonly perceived as major. By incorporating this understanding of system vulnerability with data on changes in the state of each threat (e.g., decreasing domestic pollution and increasing fishing) into a food web model, managers may be better able to estimate and predict cumulative human impacts on ecosystems and to prioritize conservation actions.
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Hori, M., Hamaoka, H., Hirota, M., Lagarde, F., Vaz, S., Hamaguchi, M., et al. (2018). Application of the coastal ecosystem complex concept toward integrated management for sustainable coastal fisheries under oligotrophication. Fish. Sci., 84(2), 283–292.
Résumé: Harmonizing coastal fisheries with water-quality improvement has become an essential factor for the sustainable use of coastal ecosystem services. Here, we present the scope of our study based on an interdisciplinary approach including ecological actions, socio-economic actions and socio-psychological actions. We chose to focus on the interaction between oyster aquaculture and seagrass vegetation as a typical ecological action using the coastal ecosystem complex (CEC) concept. Coastal organisms have adapted their traits to the environment over a long period of time, so that restoration of the CEC represents reconstruction of the original process of coastal production. Subtidal seagrass vegetation with intertidal oyster reefs is the original CEC in Japan, which would be expected to enhance coastal production by improving the production efficiency without adding nutrients. A simple field experiment examining carbon and nitrogen contents and stable isotope ratios revealed that oyster spats cultivated on a tidal flat adjacent to seagrass beds had higher nitrogen contents and higher delta C-13 ratios than spats cultivated in an offshore area using only pelagic production. This result suggests that utilization of the CEC, which enables oysters to use both pelagic and benthic production, has potential to sustain a food provisioning service for humans, even in oligotrophic conditions.
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Jueterbock, A., Bostrom, C., Coyer, J. A., Olsen, J. L., Kopp, M., Dhanasiri, A. K. S., et al. (2020). The Seagrass Methylome Is Associated With Variation in Photosynthetic Performance Among Clonal Shoots. Front. Plant Sci., 11, 571646.
Résumé: Evolutionary theory predicts that clonal organisms are more susceptible to extinction than sexually reproducing organisms, due to low genetic variation and slow rates of evolution. In agreement, conservation management considers genetic variation as the ultimate measure of a population's ability to survive over time. However, clonal plants are among the oldest living organisms on our planet. Here, we test the hypothesis that clonal seagrass meadows display epigenetic variation that complements genetic variation as a source of phenotypic variation. In a clonal meadow of the seagrassZostera marina, we characterized DNA methylation among 42 shoots. We also sequenced the whole genome of 10 shoots to correlate methylation patterns with photosynthetic performance under exposure to and recovery from 27 degrees C, while controlling for somatic mutations. Here, we show for the first time that clonal seagrass shoots display DNA methylation variation that is independent from underlying genetic variation, and associated with variation in photosynthetic performance under experimental conditions. It remains unknown to what degree this association could be influenced by epigenetic responses to transplantation-related stress, given that the methylomes showed a strong shift under acclimation to laboratory conditions. The lack of untreated control samples in the heat stress experiment did not allow us to distinguish methylome shifts induced by acclimation from such induced by heat stress. Notwithstanding, the co-variation in DNA methylation and photosynthetic performance may be linkedviagene expression because methylation patterns varied in functionally relevant genes involved in photosynthesis, and in the repair and prevention of heat-induced protein damage. While genotypic diversity has been shown to enhance stress resilience in seagrass meadows, we suggest that epigenetic variation plays a similar role in meadows dominated by a single genotype. Consequently, conservation management of clonal plants should consider epigenetic variation as indicator of resilience and stability.
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Le Fur, I., De Wit, R., Plus, M., Oheix, J., Simier, M., & Ouisse, V. (2018). Submerged benthic macrophytes in Mediterranean lagoons: distribution patterns in relation to water chemistry and depth. Hydrobiologia, 808(1), 175–200.
Résumé: A large spectrum of coastal lagoon types with a wide range of environmental conditions is observed along the French Mediterranean coast. These comprise wide trophic and salinity gradients, ranging from oligotrophic to hypertrophic status, and from nearly freshwater to slightly above marine Mediterranean Sea water salinities, respectively. The statistical analysis of a long-term dataset, including water column variables and observations of macrophyte genera, showed that salinity, depth, and then trophic status, were important factors explaining the distribution of benthic macrophytes for the soft-bottom sediments in the 34 studied French Mediterranean lagoons. Based on this, we assumed that the vegetation succession along the eutrophication gradient was different according to the lagoon salinity ranges. Euhaline and polyhaline lagoons follow the well-known Schramm schematic model, where aquatic angiosperm such as seagrasses dominate under oligotrophic conditions, and opportunistic macroalgae and phytoplankton dominate under eutrophic and hypertrophic conditions. In oligohaline and mesohaline lagoons, the succession is probably an intermediate scheme between the successions observed in small temperate lakes and in marine coastal ecosystems due to the presence of both brackish and freshwater species. We thus propose a conceptual scheme for the oligohaline and mesohaline lagoons.
Mots-Clés: southern france; eutrophication; coastal lagoon; Eutrophication; Depth; Salinity; environmental-factors; seagrass; aquatic vegetation; Canonical correspondence analysis (CCA); canonical correspondence-analysis; French coastal lagoons; potamogeton-pectinatus; spatiotemporal dynamics; Submerged aquatic vegetation (SAV); thau-lagoon
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