Jean-Claude Dauvin

Assessing coastal benthic macrofauna community condition using best professional judgement - Developing consensus across North America and Europe

Benthic indices are typically developed independently by habitat, making their incorporation into large geographic scale assessments potentially problematic because of scaling inequities. A potential solution is to establish common scaling using expert best professional judgment (BPJ). To test if experts from different geographies agree on condition assessment, sixteen experts from four regions in USA and Europe were provided species-abundance data for twelve sites per region. They ranked samples from best to worst condition and classified samples into four condition (quality) categories. Site rankings were highly correlated among experts, regardless of whether they were assessing samples from their home region. There was also good agreement on condition category, though agreement was better for samples at extremes of the disturbance gradient. The absence of regional bias suggests that expert judgment is a viable means for establishing a uniform scale to calibrate indices consistently across geographic regions.

Benthic indicators: From subjectivity to objectivity - Where is the line?

Over the last few years, the interest in using benthic indicators to assess marine environments has increased dramatically after a rather long period of relative stagnation, mostly due to the need to assess the status of coastal marine waters required by North American and European regulations. Numerous papers on this topic have been published in the domain of ecology, using a variety of different terms to refer to two categories of information: benthic species and the status of benthic communities. Nowadays, the abundant literature on these two categories makes it possible to comment on (1) the definition of the different terms used by benthic researchers, (2) the current increase of papers of rising complexity about benthic indicators, and (3) the subjectivity and objectivity involved in using benthic indicators. Faced with the increase in the number of methods, we recommend pragmatism and thus the transfer of simple methods to the research consultancies that are responsible for assessing benthic quality in numerous impact studies. Using certain procedures, such as the sentinel species, the best professional judgement (BPJ) and taxonomic sufficiency (TS), should clearly be encouraged.

Biological components from the Seine estuary: first results

The Seine estuary plays an important role in the dynamics of the eastern English Channel ecosystem. Nevertheless, its biological compartment is poorly known. This constitutes an important handicap to establish the precise state of the health of this major European estuary. The objectives of this study were to identify the life resources of the estuary: macrobenthos, mesozooplankton, suprabenthos, and fish populations and to define the main trophic links in two parts of the estuary (i. e. the polyhaline and oligohaline zones). There is an impoverishment of the biological diversity from the polyhaline zone to the oligohaline zone. The benthic and pelagic fauna of the Seine estuary is similar to other North-Eastern Atlantic estuaries. But the pelagic fauna, especially the copepod Eurytemora affinis and the shrimp Palaemon longirostris seemed to be more abundant in the Seine estuary than in other estuaries. Two macrobenthic communities occurred in the estuary: a diversified and abundant Abra alba-Pectinaria koreni community in the outer part of the estuary and a Macoma balthica community in the inner part. This latter was especially poor in specific richness, density and biomass, in all areas, except on tidal mud flats. Two trophic chains were identified. In the oligohaline zone corresponding to the maximum turbidity zone (high turbidity, low concentration of oxygen), the trophic chain was exclusively planktonic due to the dredging of the estuary which prevented permanent benthic fauna formation. In this zone, the number of fishes was relatively low in spite of high biomass of mesozooplankton and suprabenthos. In the outer part of the estuary, low turbidity and high concentration of oxygen are more favourable to fish populations which feed especially on benthic fauna.

Polychaetes from the Atlantic seamounts of the southern Azores : biogeographical distribution and reproductive patterns

A study of the polychaetes living on isolated seamounts was undertaken to give data on marine biogeography and the dispersal of marine invertebrates. The data from the Meteor and Josephine seamounts came from Hartmann-Schroder and Rosenfeldts work in the 1980s. Data from Hyeres came from Bellans work in the 1960s, and data from the Atlantis and Hyeres seamounts were obtained during the Seamount 2 French expedition on board the ‘Suroit’ in 1993. Thirty-five sites from 280 to 2205u2006m were sampled: 16 on Atlantis (13 with polychaetes), and 19 on Hyeres (16 with polychaetes). In all 84 polychaete taxa from four seamounts were studied: Atlantis, 36; Hyeres, 33; Josephine, 34; and Meteor 50, but data analysis was based on the following number of taxa: Atlantis, 31; Hyeres, 29; Josephine, 34, and Meteor 48. Two groups of sites were identified by cluster analysis: I, Atlantis and Hyeres; and II, Josephine and Meteor. Only seven species were present at all sites. Nine families were present only in group I and six other families only in group II. Hesionidae (three species) occurred in group I, conversely Syllidae (16 species) were sampled only in group II. Some of the species were cosmopolitan (31%), 49% had a large distribution in the Atlantic, 11% were lusitano–mauretanian species, and only 6% were endemic; 51% of the species have direct development against 46% of the species which had a planktotrophic development and 3% a lecithotrophic development. Results of the biogeographical distribution and reproductive patterns of the polychaetes collected on these four sites were compared.

Ecological Quality Status of the soft-bottom communities on the algerian coast: General patterns and diagnosis

Between 1995 and 2001, the soft-bottom communities along the 1180 km of the Algerian coast were sampled in nine gulfs and 12 harbours, providing a total of 655 samples. Eight macrozoobenthos-based biotic indices (S, N, H, BQI, AMBI, BENTIX, BO2A and ITI) were selected to describe the general patterns of the coastal water quality status and to establish a quality diagnosis for the different zones subjected to anthropogenic pressure (e.g., harbour construction, industrial and urban pollution). Reference values were determined for each of the eight indices selected by analyzing the indices parameter distribution. The Ecological Quality Ratio (EQR) was estimated for each index, resulting in an EQR Mean Score and an EQR Bad Score. From these EQR, we defined an EQS for each sample. The agreement between these EQS was analysed using the Kappa method in order to propose a survey strategy for the Algerian coastal waters that would take into account the soft-bottom biological compartment. The results clearly indicate that high and good quality assessments are prevalent in the gulfs, while quality assessments in harbours vary greatly from bad to good. The effect of pollution observed in the harbours can be classified in two main groups, according to when they were constructed and their relative degree of openness to the sea, which permits better water circulation and probably dilutes the pollution.

Inventory of benthic amphipods from fine sand community of the Iberian Peninsula east coast (Spain), western Mediterranean, with new records

Recent sampling surveys (2004-2008) of the shallow (12-20 m) soft-bottom homogeneous fine-sand community have allowed the collection of 55 marine amphipod species (53 Gammaridea and 2 Caprellidea) along the 250 km of Iberian Peninsula east coast (Spain, Mediterranean Sea). Among the species recorded, one recently described is new to science, five were collected for the first time in the Spanish Mediterranean and 14 were recorded for a second time confirming their presence. Of these 20 species; six are considered to be endemic to the Mediterranean Sea, seven are also north-eastern Atlantic species, and the last seven have a wide geographical distribution in the Indo-Pacific or Arctic and the Atlantic Oceans. Finally, multivariate analyses of species distribution showed changes among locations according to the north- south axis and depth, parameters that highly influence the benthic communities.

Do hydrodynamic factors affect the recruitment of marine invertebrates in a macrotidal area

For marine benthic invertebrates exhibiting complex life cycles, changes in populations’ distribution and abundance are governed by a large variety of physical, chemical and biological processes. From field observations in the Bay of Seine and laboratory experiments conducted since 1987 on the polychaete Pectinaria koreni, the present study highlights the relative importance of hydrodynamical and biological factors which affect individuals within both the planktonic and benthic phases at different scales of space and time in a macrotidal area. Pectinaria koreni is one of the main macrofaunal component of the Abra alba muddy fine sand community of the eastern Bay of Seine. Despite a highly advective and diffusive environment, a relative larval retention near adult population was reported due to some local hydrodynamics features (e.g. tidal residual circulation, Seine river plume front) and the interaction between the vertical current structure and the larval vertical migration. Although larval retention could be disrupted by wind induced currents, multiple spawning events over the reproductive period increase the likelihood that at least one larval cohort ensures a high recruitment during the life-span. Following a massive settlement whatever the sediment grain size, the newly settled larvae exhibited a high immediate decrease of their densities as a result of postlarval mortality and migration. Postlarval drifting was induced by a combination of physical factors (i.e. tidal currents and swell) and postlarval behaviour in response to sediment texture and adult/settlers interactions. According to the hydrodynamics of the bay, this process may generate a postlarval transport from offshore bottoms to coastal suitable habitats and counteract the demographic effects of larval dispersal. A conceptual model of factors governing the recruitment and population maintenance of Pectinaria koreni is proposed and discussed in comparison with results obtained on another polychaete, Owenia fusiformis, in the same area.

First record of Hemigrapsus takanoi (Crustacea: Decapoda: Grapsidae) on the western coast of northern Cotentin, Normandy, western English Channel

The sighting of the brush-clawed shore crab Hemigrapsus takanoi on the western coast of northern Cotentin confirms the extension of this species into the western part of the English Channel. This new sighting remains enigmatic because the Normanno-Breton Gulf circulation patterns do not appear to promote natural transport of crab larvae from the Atlantic or from the eastern part of the English Channel. It has been suggested that the professional oyster transport could be the origin of this species presence on this part of the French coast.

New marine amphipod records on the Algerian coast

Recent sampling surveys (2011-2012) of the shallow (0-50 m) hard-bottom communities and re-examination of some softbottom communities (5-143 m) along the Algerian coast have allowed the collection of 33 species (five Caprelloidea, 27 Gammaridea and one Hyperiidea), which were not recorded before in the inventory of the marine amphipod fauna of Algeria (Bakalem & Dauvin, 1995; Grimes et al., 2009). This paper reports the number of specimens sampled for each of these 33 species and provides data on their geographical distribution and habitats. Fourteen of the species (43%) are considered to be endemic to the Mediterranean Sea; 15 others are north-eastern Atlantic and Mediterranean species, and the four last are cosmopolitan species. Twenty-nine of the new records are known for Italian waters and 19 in Greek waters where there is intensive amphipod inventory. The total number of marine amphipod fauna in Algeria is now 332