Jérôme Jourde

Geographic patterns of biodiversity in European coastal marine benthos

Within the COST action EMBOS (European Marine Biodiversity Observatory System) the degree and variation of the diversity and densities of soft-bottom communities from the lower intertidal or the shallow subtidal was measured at 28 marine sites along the European coastline (Baltic, Atlantic, Mediterranean) using jointly agreed and harmonized protocols, tools and indicators. The hypothesis tested was that the diversity for all taxonomic groups would decrease with increasing latitude. The EMBOS system delivered accurate and comparable data on the diversity and densities of the soft sediment macrozoobenthic community over a large-scale gradient along the European coastline. In contrast to general biogeographic theory, species diversity showed no linear relationship with latitude, yet a bell-shaped relation was found. The diversity and densities of benthos were mostly positively correlated with environmental factors such as temperature, salinity, mud and organic matter content in sediment, or wave height, and related with location characteristics such as system type (lagoons, estuaries, open coast) or stratum (intertidal, subtidal). For some relationships, a maximum (e.g. temperature from 15–20°C; mud content of sediment around 40%) or bimodal curve (e.g. salinity) was found. In lagoons the densities were twice higher than in other locations, and at open coasts the diversity was much lower than in other locations. We conclude that latitudinal trends and regional differences in diversity and densities are strongly influenced by, i.e. merely the result of, particular sets and ranges of environmental factors and location characteristics specific to certain areas, such as the Baltic, with typical salinity clines (favouring insects) and the Mediterranean, with higher temperatures (favouring crustaceans). Therefore, eventual trends with latitude are primarily indirect and so can be overcome by local variation of environmental factors.

The role of physical variables in biodiversity patterns of intertidal macroalgae along European coasts

In the frame of the COST ACTION ‘EMBOS’ (Development and implementation of a pan-European Marine Biodiversity Observatory System), coverage of intertidal macroalgae was estimated at a range of marine stations along the European coastline (Subarctic, Baltic, Atlantic, Mediterranean). Based on these data, we tested whether patterns in macroalgal diversity and distribution along European intertidal rocky shores could be explained by a set of meteo-oceanographic variables. The variables considered were salinity, sea surface temperature, photosynthetically active radiation, significant wave height and tidal range and were compiled from three different sources: remote sensing, reanalysis technique and in situ measurement. These variables were parameterized to represent average conditions (mean values), variability (standard deviation) and extreme events (minimum and maximum values). The results obtained in this study contribute to reinforce the EMBOS network approach and highlight the necessity of considering meteo-oceanographic variables in long-term assessments. The broad spatial distribution of pilot sites has allowed identification of latitudinal and longitudinal gradients manifested through species composition, diversity and dominance structure of intertidal macroalgae. These patterns follow a latitudinal gradient mainly explained by sea surface temperature, but also by photosynthetically active radiation, salinity and tidal range. Additionally, a longitudinal gradient was also detected and could be linked to wave height.

Essence of the patterns of cover and richness of intertidal hard bottom communities: a pan-European study

Coastal ecosystems are highly complex and driven by multiple environmental factors. To date we lack scientific evidence for the relative contribution of natural and anthropogenic drivers for the majority of marine habitats in order to adequately assess the role of different stressors across the European seas. Such relationship can be investigated by analysing the correlation between environmental variables and biotic patterns in multivariate space and taking into account non-linearities. Within the framework of the EMBOS (European Marine Biodiversity Observatory System) programme, hard bottom intertidal communities were sampled in a standardized way across European seas. Links between key natural and anthropogenic drivers and hard bottom communities were analysed using Boosted Regression Trees modelling. The study identified strong interregional variability and showed that patterns of hard bottom macroalgal and invertebrate communities were primarily a function of tidal regime, nutrient loading and water temperature (anomalies). The strength and shape of functional form relationships varied widely however among types of organisms (understorey algae composing mostly filamentous species, canopy-forming algae or sessile invertebrates) and aggregated community variables (cover or richness). Tidal regime significantly modulated the effect of nutrient load on the cover and richness of understorey algae and sessile invertebrates. In contrast, hydroclimate was more important for canopy algae and temperature anomalies and hydroclimate separately or interactively contributed to the observed patterns. The analyses also suggested that climate-induced shifts in weather patterns may result in the loss of algal richness and thereby in the loss of functional diversity in European hard bottom intertidal areas.

Consistent patterns of spatial variability between NE Atlantic and Mediterranean rocky shores

Examining how variability in population abundance and distribution is allotted among different spatial scales can inform of processes that are likely to generate that variability. Results of studies dealing with scale issues in marine benthic communities suggest that variability is concentrated at small spatial scales (from tens of centimetres to few metres) and that spatial patterns of variation are consistent across ecosystems characterized by contrasting physical and biotic conditions, but this has not been formally tested. Here we quantified the variability in the distribution of intertidal rocky shore communities at a range of spatial scales, from tens of centimetres to thousands of kilometres, both in the NE Atlantic and the Mediterranean, and tested whether the observed patterns differed between the two basins. We focused on canopy-forming macroalgae and associated understorey assemblages in the low intertidal, and on the distribution of Patella limpets at mid intertidal levels. Our results highlight that patterns of spatial variation, at each scale investigated, were consistent between the Atlantic and the Mediterranean, suggesting that similar ecological processes operate in these regions. In contrast with former studies, variability in canopy cover, species richness and limpet abundance was equally distributed among spatial scales, possibly reflecting the fingerprint of multiple processes. Variability in community structure of low intertidal assemblages, instead, peaked at the largest scale, suggesting that oceanographic processes and climatic gradients may be important. We conclude that formal comparisons of variability across scales nested in contrasting systems are needed, before any generalization on patterns and processes can be made.

A new species of the genus Monokalliapseudes (Crustacea: Tanaidacea: Kalliapseudidae) from French Guiana

Abstract A new species, Monokalliapseudes guianae, is described from French Guianese estuaries. It is distinguishable from its only congener most notably by lacking an exopodite on pereopod 1 and by the nature of the basal article of the uropod. The inner distal corner of the basal article is only slightly produced and lacks a rounded lobe. The bases of pereopods 2 and 3 lack numerous long setae. Sexual dimorphism is observed in the antennule, cheliped, and pereopod 1. Depending on size, males can exhibit two forms of chelae. A new diagnosis is presented for the genus Monokalliapseudes.

Malmgrenia louiseae sp. nov., a new scale worm species (Polychaeta: Polynoidae) from southern Europe with a key to European Malmgrenia species

Malmgrenia louiseae sp. nov. is described from both the western Mediterranean in the Gulf of Lions, and the north-east Atlantic from off Portugal and the Bay of Biscay. The species was found in muddy sediments in shallow water and is possibly associated with echiurids or synaptid holothurians. Malmgrenia louiseae sp. nov. can be clearly distinguished from all other known Malmgrenia species by the presence of an infra-acicular process in addition to the supra-acicular process on the acicular lobe of the neuropodia, the lack of microtubercules on the elytra, two kinds of notochaetae (stout with blunt tip and slender with fine pointed tip), and exclusively unidentate neurochaetae. An identification key to the north-east Atlantic and Mediterranean Malmgrenia species is provided.

Chaetozone corona (Polychaeta, Cirratulidae) in the Bay of Biscay: a new alien species for the North-east Atlantic waters?

The cirratulid species Chaetozone corona is reported for the first time from the North-east Atlantic waters. Several specimens were collected during oceanographic surveys between 1996 and 2015 from soft bottom habitats along the coasts of Brittany (Western France). This species, originally described from the coast of California, was recently recorded for the first time from the Mediterranean Sea. We hypothesize that this species could have been recently introduced to the Atlantic coasts of Europe and colonized the northern coast of Bay of Biscay from the Loire estuary to the Iroise Sea. We discuss the potential vectors of introduction and the main environmental factors that could explain its current distribution. An identification key to all the known North-east Atlantic species of Chaetozone is given.

Persistent benthic communities in the extreme dynamic intertidal mudflats of the Amazonian coast: an overview of the Tanaidacea (Crustacea, Peracarida)

The extreme dynamics of the Amazonian coast and associated mudbanks raises questions about their unknown resistant infauna. In order to fill the gap, we investigated the seasonal variations of species composition, abundance and population structure of Tanaidacea in two dynamic mudbanks near the coast of French Guiana. Despite the low species richness recorded for this taxon, the very high densities and biomass of tanaids constituted a potential plentiful trophic resource for many coastal species, such as shorebirds, fish, shrimps, and crabs. The estuarine habitat at Sinnamary presented more tanaid species than the bare marine mudflat at Awala-Yalimapo. All species showed strong female-biased sex ratios and differed in range of total length and stage of maturity. The species with smaller body size with sexual maturity occurring at an earlier stage were dominant and widely distributed. Pore water salinity and predator pressure may be considered key factors driving seasonal variations of tanaid abundance and population structure. This study gives a novel insight into the macrobenthos communities along the highly dynamic Amazonian coast.