Hugues Blanchet

Indicator-Based Assessment of Marine Biological Diversity–Lessons from 10 Case Studies across the European Seas

The Marine Strategy Framework Directive requires the environmental status of European marine waters to be assessed using biodiversity as one out of 11 descriptors, but the complexity of marine biodiversity and its large span across latitudinal and salinity gradients have been a challenge to the scientific community aiming to produce approaches for integrating information from a broad range of indicators. The Nested Environmental status Assessment Tool (NEAT), developed for the integrated assessment of the status of marine waters, was applied to ten marine ecosystems to test its applicability and compare biodiversity assessments across the four European regional seas. We evaluate the assessment results as well as the assessment designs of the ten cases, and how the assessment design, particularly the choices made regarding the area and indicator selection, affected the results. The results show that only 2 out of the 10 case study areas show more than 50 % probability of being in good status in respect of biodiversity. No strong pattern among the ecosystem components across the case study areas could be detected, but marine mammals, birds, and benthic vegetation indicators tended to indicate poor status while zooplankton indicators indicated good status when included into the assessment. The analysis shows that the assessment design, including the selection of indicators, their target values, geographical resolution and habitats to be assessed, has potentially a high impact on the result, and the assessment structure needs to be understood in order to make an informed assessment. Moreover, recommendations are provided for the best practice of using NEAT for marine status assessments.

Seagrass burial by dredged sediments: Benthic community alteration, secondary production loss, biotic index reaction and recovery possibility

In 2005, dredging activities in Arcachon Bay (France) led in burying 320,000 m(2) of Zostera noltii intertidal seagrass. Recovery by macrobenthos and seagrass was monitored. Six months after works, seagrass was absent and macrobenthos drastically different from surrounding vegetated stations. Rapidly and due to sediment dispersal, disposal area was divided into a sandflat with a specific benthic community which maintained its difference until the end of the survey (2010), and a mudflat where associated fauna became similar to those in adjacent seagrass. Macrobenthic community needs 3 years to recover while seagrass needs 5 years to recover in the station impacted by mud. The secondary production loss due to works was low. In this naturally carbon enriched system, univariate biotic indices did not perform well to detect seagrass destruction and recovery. Multivariate index MISS gave more relevant conclusions and a simplified version was tested with success, at this local scale.

What Is Marine Biodiversity? Towards Common Concepts and Their Implications for Assessing Biodiversity Status

‘Biodiversity’ is one of the most common keywords used in environmental sciences, spanning from research to management, nature conservation and consultancy. Despite this, our understanding of the underlying concepts varies greatly, between and within disciplines as well as among the scientists themselves. Biodiversity can refer to descriptions or assessments of the status and condition of all or selected groups of organisms, from the genetic variability, to the species, populations, communities, and ecosystems. However, a concept of biodiversity also must encompass understanding the interactions and functions on all levels from individuals up to the whole ecosystem, including changes related to natural and anthropogenic environmental pressures. While biodiversity as such is an abstract and relative concept rooted in the spatial domain, it is central to most international, European and national governance initiatives aimed at protecting the marine environment. These rely on status assessments of biodiversity which typically require numerical targets and specific reference values, to allow comparison in space and/or time, often in association with some external structuring factors such as physical and biogeochemical conditions. Given that our ability to apply and interpret such assessments requires a solid conceptual understanding of marine biodiversity, here we define this and show how the abstract concept can and needs to be interpreted and subsequently applied in biodiversity assessments.

Limited Consequences of Seagrass Decline on Benthic Macrofauna and Associated Biotic Indicators

Marine phanerogams are ecosystem engineers, as their presence induces major environmental changes that impact on the benthic fauna. Consequently, modifications to the structure of benthic communities would be expected to be associated with seagrass decline. Since 2005, Zostera noltii seagrass beds in Arcachon Bay (France), the largest in Europe, have undergone a severe decline. Twelve stations distributed throughout the lagoon were sampled in 2002, and all were found to be densely planted at that time. Subsequently, the same stations were revisited in 2010 and seagrass cover had drastically decreased by that time. Based on benthic macrofauna, multidimensional scaling (MDS) analysis identified four groups. Years were separated. In 2002, two groups were distinct in relation to the water body, since in 2010 separation between the two other groups was related to seagrass occurrence. When looking at community structure and dominant species there were moderate differences within and between years, independent of seagrass decline. Seagrass loss did not drastically modify the species composition as they were preserved in the remaining seagrass patches. However, there was a drop in macrofauna abundance in unvegetated muddy compared with abundance in the remaining seagrass areas. Epifauna was particularly affected by seagrass decline. Among biotic indicators based on macrofauna, multivariate indicator MISS (Macrobenthic Index in Sheltered Systems) was in agreement with the similarity of macrofauna structure among groups, while other tested indicators performed badly in relation to seagrass occurrence. However, no index detected seagrass loss, highlighting the necessity of maintaining a separate survey on seagrass cover.

Main Ecological Features of Benthic Macrofauna in Mediterranean and Atlantic Intertidal Eelgrass Beds: A Comparative Study

Main Ecological Features of Benthic Macrofauna in Mediterranean and Atlantic Intertidal Eelgrass Beds: A Comparative Study The present study compares the intertidal eelgrass macrofauna in two geographically and ecologically disparate localities (central Mediterranean and eastern Atlantic). Both coastal ecosystems are developed on extensive large mudflats with eelgrass beds, hosting a great diversity of water birds and providing important socio-economic assets. These two distinct and distant geographical ecosystems are affected by numerous anthropogenic pressures. By reflecting the response of the structure and functioning of benthic communities to climate change, the two eelgrass ecosystems provide a natural laboratory to investigate global warming. The macrobenthic fauna community of Zostera (Zosterella) noltei eelgrass beds was studied by sampling 34 stations in the Kneiss Islands and 48 stations in Arcachon Bay. A total of 148 species are identified in the Kneiss islands and 117 species in Arcachon Bay, but only 23 species are common to both ecosystems. Diversity, abundance and community structure are significantly different between the two study areas, which could be explained by differences between Mediterranean and Atlantic climatic conditions and by anthropic factors (e.g. fishing pressure, pollution, nutrient inputs) affecting each ecosystem. Multidimensional scaling (n-MDS) analysis identifies two distinct geographical station groups on the basis of species and familylevel abundance. On the contrary, three assemblages are identified on the basis of trophic groups distributed between the separate ecosystems. In terms of ecological quality status, the Kneiss site appears to have a good ecological condition and hosts a variety of sensitive species. On the other hand, biotic indices indicate that the Arcachon site is moderately perturbed and that the benthic communities are unbalanced. It is expected that the present-day functioning of the Kneiss Islands ecosystem will become typical of the situation in Arcachon Bay in several decades time, with the development of warmer and drier conditions.

New records of Spio symphyta and Spio martinensis (‘Polychaeta’: Canalipalpata: Spionidae) from Arcachon Bay (France), NE Atlantic

This paper presents new records of Spio symphyta Meißner et al., 2011 and Spio martinensis Mesnil, 1896 (‘Polychaeta’: Canalipalpata: Spionidae) from Arcachon Bay (southern Bay of Biscay). For both species the new records represent an extension of their known distributional range. The two species have probably been present in Arcachon Bay for several years but were confused with other species of the genus Spio. Spio symphyta was identified at five locations in Arcachon Bay in 2009 and 2013 and S. martinensis at three stations in 2012 and 2013. A detailed and illustrated description of specimens from Arcachon Bay is provided. Important characters of Spio spp. occurring in the area are compared.