European Atlantic Shelf Research Articles

Late Miocene palaeobiogeography of the Mediterranean-Atlantic Region: An analysis based on shelf ostracod assemblages of the Northwestern Morocco

A Late Miocene palaeobiogeographic framework of the Mediterranean-Atlantic Region, based on a comparative study of the continental shelf ostracod assemblages collected from a section in the Saïss Basin, northwestern Morocco, is proposed. Distribution data and statistical analyses allowed to identify six palaeoecoregions. Five of these units, that is South European Atlantic Shelf, Saharan Upwelling, Adriatic Sea, Western Mediterranean and Alboran Sea, were identified according to the ecoregions used in modern biogeographic frameworks. For the easternmost part of the Proto-Mediterranean basin a “Late Miocene Southeastern Mediterranean” palaeoecoregion is proposed. The Tortonian-Messinian palaeobiogeography of the so-called “Miocene European-West African Province”, preceding the onset of the Messinian Salinity Crisis, was under the influence of the relationships between Atlantic and Proto-Mediterranean biota in tropical, subtropical and possibly warm temperate waters.

Miocene sponge assemblages in the face of the Messinian Salinity Crisis-new data from the Atlanto-Mediterranean seaway.

The Messinian Salinity Crisis is considered as one of the most influential Cenozoic events that impacted negatively on the benthic fauna of the Mediterranean area. Changing environmental conditions, including a sharp reduction of water exchange between the Mediterranean Sea and the Atlantic Ocean, altered the geographical ranges of many organisms, including sponges (Porifera). Here, we report a unique assemblage of isolated sponge spicules from the upper Miocene of southwestern Spain. The newly recognized sponge fauna was inhabiting the Guadalquivir Basin-the corridor between the Mediterranean and the Atlantic Ocean at that time. It represents a taxonomically rich sponge community that consisted of members of "soft" and "lithistid" demosponges and hexactinellids. Demosponges are represented by at least thirty-four taxa, while hexactinellids are significantly rarer; only six taxa have been identified. From among eighteen taxa recognized to the species level, at least eight seem to be inhabiting this area to these days; six are recorded from adjacent areas, such as the Western Mediterranean, South European Atlantic Shelf, and the Azores, and three are present in the Red Sea and/or the Northern Atlantic. Intriguingly, some taxa seem to have their closest relatives in distant areas, such as the Indo-Pacific and Japanese waters which suggests that the range of some once widely-distributed populations shrunk after the isolation of the Mediterranean and the Messinian Salinity Crisis, surviving to the present day only in refugia.

Robust identification of potential habitats of a rare demersal species (blackspot seabream) in the Northeast Atlantic

Species distribution models (SDM) are commonly used to identify potential habitats. When fitting them to heterogeneous, opportunistically collated presence/absence data, imbalance in the number of presence and absence observations often occurs, which could influence results. To robustly identify potential habitats for blackspot seabream (Pagellus bogaraveo) throughout its distribution area in the Northeast Atlantic and the western Mediterranean Sea, we used an ensemble species distribution modelling (eSDM) approach, modelling gridded presence–absence data with environmental predictors for two types of occurrence data sets. The first data set displayed the observed unbalanced spatially heterogeneous presence/absence ratio and the second a balanced presence/absence ratio. The data covered the full distribution area, including the European Atlantic shelf, the Azorean region and the Western Mediterranean Sea. Across these regions, populations display variable status. The main environmental predictors for potential habitats were bathymetry and annual maximum SST. The fitted ensemble compromise (eSDM) was projected over the whole grid to create a habitat suitability map. This map exhibited higher probabilities of presence for the balanced-ratio data set. A binary presence–absence map was then generated using optimized presence probability thresholds for four validation indices. Using the true skill statistic to optimize the threshold, the surface areas of the binary presence–absence map was 53% smaller for the balanced data set than for the observed unbalanced data set. However, the choice of validation index had an even greater impact (up to 15 000%). This indicates that studies using opportunistic data for SDM fitting need to pay attention to the effects of presence/absence data imbalance and the choice of validation index to fully evaluate uncertainty.

Climate-induced changes in ocean productivity and food-web functioning are projected to markedly affect European fisheries catch

In European waters, climate-induced changes in ocean conditions will alter marine ecosystems, leading to potential repercussions for the European fisheries and the status of exploited species. Here, we used a new version of the EcoTroph model, forced by a regional high-resolution coupled hydrodynamic-ecosystem model, to investigate the effects of climate change on biomass and catch in 15 areas (ICES divisions) of the European Atlantic shelf ecosystems. Based on the projected changes in temperature, zooplankton and benthic secondary producers, we modeled the changes in biomass and catch at each trophic level by the end of the 21st century. We projected that total biomass and catch for the whole Atlantic European seas would decrease by 11.5 and 10.0%, respectively, by 2090-2099 relative to 2013-2017 under a ‘no mitigation’ greenhouse gases emissions scenario (RCP8.5). The projected decrease in catch is 310000 or 240000 t by 2090-2099 under a high (RCP8.5) or a moderate (RCP4.5) emissions scenario, respectively. Some areas, such as the Celtic Sea, would be more affected than others, while the climate impact on the bentho-demersal biomass and catches would be more pronounced, especially toward the higher trophic levels. Our study suggests that climate change may strongly impact European fisheries, with ecological consequences and potential socio-economic repercussions. Future studies using alternative climate and ecosystem models would allow the exploration of uncertainties in projected biomass and catch. While fisheries management is required to adapt to these changes, the projected impacts on catch cannot be avoided without aggressive mitigation of greenhouse gas emissions.

Corrigendum: Advection and composition of Dinophysis spp. populations along the European Atlantic shelf

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Advection and Composition of Dinophysis spp. Populations Along the European Atlantic Shelf

The main objective was to study relationships between the regional biogeography of Dinophysis species and water masses circulation along the European Atlantic coast. Hydrodynamic connectivities were estimated with a Lagrangian approach. Available and validated physical hindcasts from regional hydrodynamical models, with different resolutions were used. The target area is the Bay of Biscay (NE Atlantic) and connectivity was evaluated between a set of spatially distributed stations and during temporally specified periods. Different indexes related to connectivity properties such as mean, median, most frequent transit times were calculated. To illustrate the dispersion pattern, a molecular approach was jointly set-up to describe the species composition of this genus. At the seasonal scale, a high connectivity within the Bay of Biscay was observed with a slight northward connectivity from Galicia coastal waters to the Shelf of the Bay of Biscay. By comparison to the connectivity between shelf waters of French Brittany and English Channel waters, a higher connectivity between shelf waters of French Brittany and the Celtic Sea shelf was observed. The species mixing in the Bay of Biscay from Galicia waters to the Celtic Sea was confirmed by the genetic analyses despite the absence of Dinophysis sacculus in natural samples. The molecular methodology developed for this work, permitting at least the description of the species composition, also highlights, at the European scale, an unexpected low genetic variability which echoes the complex taxonomic classification inside the genus and the difficulties encountered by national monitoring programs to reach a taxonomic resolution at species level. It is now necessary to start some monitoring at the species level before realizing mid- or long-term forecasts.

Unreported catches, impact of whaling and current status of blue whales in the South European Atlantic Shelf

The North Atlantic blue whale was depleted by modern whaling and it is still considered to be highly endangered. Despite its protection in 1954, catches continued in the South European Atlantic Shelf (SEAS) region and immediately adjacent waters until 1979. We compiled catches and investigate abundance trends in the region using original data from whaling (1921–1985) and scientific surveys around the last years of exploitation (1981–1987). The struck and lost rate was estimated at 3.2% for sperm whales and 2.3% for baleen whales. The compiled records include 60 catches, with an additional 1–2 blue whales likely struck and lost. From these, 29 individuals had been correctly reported as blue whales but 31 were mislabelled as fin whales. After correcting for loss rates, the number of blue whales killed in the region was estimated at 61 in 55 years (1.12 individuals/year). The data from the 1950s shows some oversized fin whales but it is unclear whether they are due to an incorrect reporting of species or to incorrect measurements, so it cannot be discarded that the actual number of blue whales caught was slightly higher than estimated. Mean body length of reported blue whales was lower than in higher latitudes of the North Atlantic, probably reflecting geographical stratification with higher proportion of immatures in the SEAS. The ratio between catches or sightings of blue whales and those of fin whales was 5.9% in the southern part of the SEAS previous to exploitation, it declined to 0.02–0.18% in the 1920s, and increased thereafter up to 1.6% in the 1980–1990s. Taking as reference the population size of fin whales in the SEAS, that of blue whales at the end of the 1980s can be guessed to be at ca337-497 individuals. Considering accepted population estimates in other areas as well as the observed rates of increase, current abundance is thought to be over a thousand whales in the SEAs and at in the order of 4000–5000 individuals for the whole eastern North Atlantic basin.

Snapshot of Macroalgae and Fish Assemblages in Temperate Reefs in the Southern European Atlantic Ecoregion

Most of the biodiversity studies in the South European Atlantic Shelf ecoregion are limited to shallow subtidal or intertidal habitats, while deeper reef habitats, also of relevant ecological importance, are particularly understudied. Macroalgal communities, associated fauna, and sea surface temperature were studied in deep reefs (25–30 m) at two locations in this ecoregion: Parcel, North of Portugal (41° N), and Tarifa, Southern Spain (35° N). Specifically, algal assemblages were assessed using biomass collection and associated ichthyofauna was assessed using visual census techniques using scuba. Seawater surface temperature was higher (>3 °C) in the southern region—Tarifa, compared to the northern region—Parcel. Our survey revealed 18 fish species and 23 algae species. The highest abundance of cold-water species (both macroalgae and fish species) was recorded in Parcel and warm-water species were dominant in Tarifa. In light of climate global trends, both regions might experience biodiversity shifts towards tropicalization. Current knowledge on their biodiversity is imperative to further evaluate potential shifts.

Restructuring of the \u2018Macaronesia\u2019 biogeographic unit: A marine multi-taxon biogeographical approach

The Azores, Madeira, Selvagens, Canary Islands and Cabo Verde are commonly united under the term “Macaronesia”. This study investigates the coherency and validity of Macaronesia as a biogeographic unit using six marine groups with very different dispersal abilities: coastal fishes, echinoderms, gastropod molluscs, brachyuran decapod crustaceans, polychaete annelids, and macroalgae. We found no support for the current concept of Macaronesia as a coherent marine biogeographic unit. All marine groups studied suggest the exclusion of Cabo Verde from the remaining Macaronesian archipelagos and thus, Cabo Verde should be given the status of a biogeographic subprovince within the West African Transition province. We propose to redefine the Lusitanian biogeographical province, in which we include four ecoregions: the South European Atlantic Shelf, the Saharan Upwelling, the Azores, and a new ecoregion herein named Webbnesia, which comprises the archipelagos of Madeira, Selvagens and the Canary Islands.

Disentangling latitudinal diversity gradients in Taxonomic, Phylogenetic, and Functional diversity of Atlantic reef fishes

Disentangling latitudinal diversity gradients in Taxonomic, Phylogenetic, and Functional diversity of Atlantic reef fishes

Fish Species in a Changing World: The Route and Timing of Species Migration between Tropical and Temperate Ecosystems in Eastern Atlantic

The presence of tropical species has been reported in Atlantic-European waters with increasing frequency in recent years. Unfortunately, the history of their migrations is not well understood. In this study, we examined the routes and timing of fish migrations in several ecosystems of the East Atlantic Ocean, combining several publicly available and unpublicized datasets on species occurrences. The species studied were those noted as exotic or rare outside their previous known area of distribution. We used sea surface temperature (SST) data obtained from 30 years of satellite observation to define three distinct time periods. Within these periods, temperature trends were studied in six ecosystems: the North Sea, the Celtic Sea, the South European Atlantic Waters, the Mediterranean Sea, the Canary Current and the Guinea Current. We also incorporated bathymetry data to describe the distribution of species. Measurement across a relatively large spatial extent was made possible by incorporating the capabilities of GIS. While SST increased consistently over time in all of the ecosystems observed, the change in number of species differed among ecosystems. The number of species in the middle regions, such as the South European Atlantic Shelf and the Western Mediterranean Sea, tended to increase over time. These regions received numbers of species from the lower or the upper latitudes according to season. Of all of the species observed in the recent period, 7 species from the Canary Current tended to be found in the Western Mediterranean Sea, and 6 species from these two regions extended their distributions to the South European Atlantic Shelf. Twelve species from the Canary Current moved seasonally to the Guinea Current. In the northern regions, 13 species moved seasonally in the North Sea and the Celtic Seas, and 12 of these species reached the South European Atlantic Shelf. This study presents a picture of routes and timing of species migration at the biogeographical scale. It shows how species have shifted their area of distribution (mostly northward) along the Eastern Atlantic ecosystems or have increased their depth ranges probably to remain within their preferred temperature range in response to long-term and seasonal environmental changes.

Towards a functional characterization of rocky reefs marine habitats

Event Abstract Back to Event Towards a functional characterization of rocky reefs marine habitats María Rodríguez González1*, Natalí D. Lazzari1, Laura Palacín Fernández1, Jose A. Sanabria1 and Mikel A. Becerro1 1 Spanish Scientific Research Council, Natural Products and Agrobiology Institute CSIC, Spain Habitat heterogeneity is a major component of biodiversity as it determines species distribution and abundance. Habitat loss, with its associated loss of species, food resources, and ecosystem functioning, is identified as one of the major threats to marine biodiversity. Traditionally, the analysis of taxonomic diversity dominates community level approaches. But species losses or additions can generate major or minor impacts in multiple ecosystem processes depending on their functional traits. Recently, there are an increasing number of researches that approach ecosystem dynamics based on species functional traits. Yet, we still have no description of habitats based on their functional characteristics. Here, we carried out a functional level characterization of the different habitats present on Spanish littoral reefs. We have used underwater visual census that follow the Reef Life Survey methodology to quantify fish, invertebrate, and sessile communities in more than 250 locations scattered over the Spanish and Portuguese coasts. We have quantified the sessile community with over 5.000 photoquadrats distributed along five marine ecoregions: Alboran Sea, Macaronesian, Saharan upwelling, South European Atlantic Shelf and Western Mediterranean. We have described 16 functional traits, including algae, sessile animals, and substrate types. These traits have allowed us to determine 13 functional marine habitats differentially distributed over the coast of Portugal, Spain, and associated archipelagos. The largest functional habitat covers 18% of the rocky reefs and it is dominated by corticated macrophytes (28%), filamentous algae (20%), and bare rock (18%) functional groups. Functional habitats dominated by leathery functional group and filamentous functional group account of 2% and 3% of rocky reefs and are not represented in marine protected areas. Our results suggest that Spain and Portugal have a large number of functional habitats heterogeneously distributed in their coastal waters. Because each habitat is restricted to a specific range in the functional space, effective conservation of each habitat is mandatory to maximize the functional diversity of rocky reefs. Our characterization of functional habitats is a first approach to increase our understanding of the functional diversity of marine benthic communities, which can lead to more effective conservation actions. Keywords: Marine habitat, functional groups, Rocky reef, Biodiversity, conservation Conference: XIX Iberian Symposium on Marine Biology Studies, Porto, Portugal, 5 Sep - 9 Sep, 2016. Presentation Type: Oral Presentation Topic: 1. ECOLOGY, BIODIVERSITY AND VULNERABLE ECOSYSTEMS Citation: Rodríguez González M, Lazzari ND, Palacín Fernández L, Sanabria JA and Becerro MA (2016). Towards a functional characterization of rocky reefs marine habitats. Front. Mar. Sci. Conference Abstract: XIX Iberian Symposium on Marine Biology Studies. doi: 10.3389/conf.FMARS.2016.05.00068 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 18 May 2016; Published Online: 02 Sep 2016. * Correspondence: Miss. María Rodríguez González, Spanish Scientific Research Council, Natural Products and Agrobiology Institute CSIC, San Cristóbal de La Laguna, Santa Cruz de Tenerife, 38206, Spain, maria.rguez92@hotmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers María Rodríguez González Natalí D Lazzari Laura Palacín Fernández Jose A Sanabria Mikel A Becerro Google María Rodríguez González Natalí D Lazzari Laura Palacín Fernández Jose A Sanabria Mikel A Becerro Google Scholar María Rodríguez González Natalí D Lazzari Laura Palacín Fernández Jose A Sanabria Mikel A Becerro PubMed María Rodríguez González Natalí D Lazzari Laura Palacín Fernández Jose A Sanabria Mikel A Becerro Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Marine resilience distribution in the Alboran Sea ecoregion

Event Abstract Back to Event Marine resilience distribution in the Alboran Sea ecoregion Jose A. Sanabria1*, Natalí D. Lazzari1, María Rodríguez González1 and Mikel A. Becerro1 1 Spanish Scientific Research Council, Natural Products and Agrobiology Institute, Spain The Alboran Sea is an ecoregion in between the South European Atlantic Shelf and the Western Mediterranean ecoregions. Oceanographic conditions in the Alboran Sea are strongly influenced by Atlantic and Mediterranean currents, which suggest that this particular ecoregion could function as a transition zone from Atlantic to Mediterranean biodiversity. The Alboran Sea ecoregion is a major contributor to species richness of temperate seas and it is consider a biodiversity hotspot, but we know very little about the resistance and resilience of this region, i.e., the capacity of the region to resist to and recover from disturbance. Both resistance and resilience are critical components for a healthy ocean and a warranty to ensure effective conservation. Our study used a resilience framework to calculate an index based on a number of indicators that are known to directly affect the resilience of temperate benthic communities. Our results showed that marine resilience increased progressively and significantly from western to eastern Alboran Sea. Maximum resilience values occurred on marine protected areas. Whether the high resilience values of protected communities are a cause or a consequence of protection remains unclear, but our study supports the hypothesis that protection increases the capacity of the system to recover from disturbance and sets forth a number of hypotheses prone to experimental testing. Keywords: resilience, Alboran Sea, Marine diversity, protected areas, Rocky reef Conference: XIX Iberian Symposium on Marine Biology Studies, Porto, Portugal, 5 Sep - 9 Sep, 2016. Presentation Type: Poster Presentation Topic: 1. ECOLOGY, BIODIVERSITY AND VULNERABLE ECOSYSTEMS Citation: Sanabria JA, Lazzari ND, Rodríguez González M and Becerro MA (2016). Marine resilience distribution in the Alboran Sea ecoregion. Front. Mar. Sci. Conference Abstract: XIX Iberian Symposium on Marine Biology Studies. doi: 10.3389/conf.FMARS.2016.05.00156 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 18 May 2016; Published Online: 03 Sep 2016. * Correspondence: Mr. Jose A Sanabria, Spanish Scientific Research Council, Natural Products and Agrobiology Institute, San Cristobal de La Laguna, Santa cruz de Tenerife, 38206, Spain, jose.sanabria@csic.es Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Jose A Sanabria Natalí D Lazzari María Rodríguez González Mikel A Becerro Google Jose A Sanabria Natalí D Lazzari María Rodríguez González Mikel A Becerro Google Scholar Jose A Sanabria Natalí D Lazzari María Rodríguez González Mikel A Becerro PubMed Jose A Sanabria Natalí D Lazzari María Rodríguez González Mikel A Becerro Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Macroecological analysis of the fish fauna inhabiting Cymodocea nodosa seagrass meadows.

In this study, patterns in the taxonomic richness and composition of the fish fauna inhabiting Cymodocea nodosa seagrass meadows were described across their entire distribution range in the Mediterranean Sea and adjacent Atlantic Ocean. Specifically, the study tested whether there are differences in the composition of fish assemblages between those ecoregions encompassed by the distribution range of C. nodosa, and whether these differences in composition are connected with differences in bioclimatic affinities of the fish faunas. A literature review resulted in a total of 19 studies, containing 22 fish assemblages at 18 locations. The ichthyofauna associated with C. nodosa seagrass meadows comprises 59 families and 188 species. The western Mediterranean (WM) Sea has the highest species richness (87 species). Fish assemblages from the Macaronesia-Canary Islands, the Sahelian Upwelling, South European Atlantic Shelf and the WM differ, in terms of assemblage composition, relative to other ecoregions. In contrast, the composition of the fish fauna from the central and eastern Mediterranean overlaps. There is a significant serial correlation in fish assemblage composition between adjacent ecoregions along the distribution range of C. nodosa. Dissimilarities in assemblage composition are connected with the geographical separation between locations, and the mean minimum annual seawater temperature is the environmental factor that explains most variation in fish assemblage composition.

Five new records and one new species of Polycladida (Platyhelminthes) for the Cantabrian coast (North Atlantic) of the Iberian Peninsula

The Iberian Peninsula is part of the South European Atlantic Shelf within the Lusitanian ecoregion. Given the characteristics of this region, a great invertebrate biodiversity is expected. Nevertheless, no literature records of Polycladida are known for the Cantabrian Sea. Here, we report the presence of six polyclad species, including one new species.Notoplana vitrea, considered endemic to the Mediterranean Sea, was found in the Cantabrian Sea, demonstrating its presence in Atlantic waters. This species was previously reported for these waters on two natural history photographic websites: the importance of searching, indexing and disseminating this type of record for the scientific community is discussed.Discocelis tigrinais reported for the first time for the Cantabrian Sea, and is the northernmost record to date. In this paper,Pleioplana atomatais reported for the second time for the Iberian Peninsula, yet is the first record for the Cantabrian Sea. Although a literature record ofLeptoplana tremellarisfor the Iberian Peninsula exists, it is considered a misidentification ofL. mediterranea; therefore, this work provides the first record ofL. tremellarisfor the Iberian Peninsula. The cosmopolitan speciesCycloporus papillosusis also reported for the Cantabrian Sea. A new species,Imogine fafaisp. nov., is described and taxonomically compared with other species of the genus.

Including cetaceans in multi-species assessment models using strandings data: why, how and what can we do about it?

Including cetaceans in multi-species assessment models using strandings data: why, how and what can we do about it?

Cetacean abundance and distribution in European Atlantic shelf waters to inform conservation and management

The European Union (EU) Habitats Directive requires Member States to monitor and maintain at favourable conservation status those species identified to be in need of protection, including all cetaceans. In July 2005 we surveyed the entire EU Atlantic continental shelf to generate robust estimates of abundance for harbour porpoise and other cetacean species. The survey used line transect sampling methods and purpose built data collection equipment designed to minimise bias in estimates of abundance. Shipboard transects covered 19,725km in sea conditions ⩽Beaufort 4 in an area of 1,005,743km2. Aerial transects covered 15,802km in good/moderate conditions (⩽Beaufort 3) in an area of 364,371km2. Thirteen cetacean species were recorded; abundance was estimated for harbour porpoise (375,358; CV=0.197), bottlenose dolphin (16,485; CV=0.422), white-beaked dolphin (16,536; CV=0.303), short-beaked common dolphin (56,221; CV=0.234) and minke whale (18,958; CV=0.347). Abundance in 2005 was similar to that estimated in July 1994 for harbour porpoise, white-beaked dolphin and minke whale in a comparable area. However, model-based density surfaces showed a marked difference in harbour porpoise distribution between 1994 and 2005. Our results allow EU Member States to discharge their responsibilities under the Habitats Directive and inform other international organisations concerning the assessment of conservation status of cetaceans and the impact of bycatch at a large spatial scale. The lack of evidence for a change in harbour porpoise abundance in EU waters as a whole does not exclude the possibility of an impact of bycatch in some areas. Monitoring bycatch and estimation of abundance continue to be essential.

Regional Objective Analysis for Merging High-Resolution MERIS, MODIS/Aqua, and SeaWiFS Chlorophyll- a Data From 1998 to 2008 on the European Atlantic Shelf

In this paper, we define the method that is used to merge high-resolution multisensor chlorophyll-a (chl-a) data on the Ireland-Biscay-Iberia Regional Ocean Observing System area from 1998 to the present at a resolution of 1.1 km. The method is based on geostatistics and is known as kriging. The merged variable is the daily anomaly of chl-a, with the anomaly being defined as the difference between the daily image and the mean historical field for the considered day. For each day, the continuous anomaly image is generated using the kriging method, and the mean historical field is then added to obtain the cloudless field of chl- a. The initial satellite chl-a data set used in the merging procedure is derived from the daily level-2 water leaving radiances of three ocean color sensors: the Sea-Viewing Wide Field of View Sensor on the Orbview platform, the Moderate Resolution Imaging Spectroradiometer on the Aqua platform, and the Medium Resolution Imaging Spectrometer Instrument on the ENVISAT platform. The chl-a concentration is obtained using a specific algorithm developed by Ifremer, known as OC5 product. Before merging, each satellite-derived chl-a product has been compared to in situ data and has been validated using a matchup data set. After this validation against in situ data, intercomparisons between the satellite data sets have been performed. As the chl-a anomaly variability depends, in this region, on the season and the distance from the shore, local space-time semivariograms have been calculated to estimate the spatiotemporal dependence or covariance of the chlorophyll anomalies. The semivariograms, used in the estimation of the kriged anomaly, are defined by their nuggets (noise), their spatial and temporal range (maximum distance for a nonnull covariance between the anomalies), and their sill (maximum variance). The spatial range of the semivariogram has been approximated locally on a regular grid. The nuggets and the sills have been deduced from the square of the mean of the chl-a concentration (the climatological reference) as we have observed a classical proportionality effect between the square of the chl-a mean, the variance of the distribution, and the parameters of the semivariograms. Compared to each original product, the analysis shows a complete coverage and differences with the in situ data that are statistically equivalent to those observed with the initial satellite data set. The merged product offers a number of applications for environmental monitoring such as the monitoring of the eutrophication risk required by the Water Framework Directive of the European Union.

Remote sensing with SPOT-4 for mapping kelp forests in turbid waters on the south European Atlantic shelf

Remote sensing has become an increasingly used technique for the thematic mapping of large marine areas. In recent years, many researchers have successfully applied these techniques in different places for benthic mapping in clear waters; however, areas with turbid waters present important limitations that are gradually being solved by recent technological advances. In this context, the main objective of the present study is to develop and validate a methodology for mapping intertidal and subtidal kelp forests in the Galician coast (NW Spain), based on images from SPOT-4 (Satellite Pour l’Observation de la Terre). Three analysis methods have been applied: visual analysis and interpretation, unsupervised classification (cluster) and supervised classification (angular classification and maximum likelihood classification). Classification percentages higher than 70% in all substrates were obtained both using visual analysis and interpretation and maximum likelihood classification.

Metal distributions and their fluxes at the coastal boundary of a semi-enclosed ria

Water column samples have been collected in the outer channel of the Ferrol Ria (NW Spain) during four occasions over a tidal cycle. The objective was to study the exchange of dissolved and particulate Cd, Cu, Pb and Zn and particulate Al, Fe and Si between the ria and the adjacent coastal waters. This study provides the first extensive dataset on dissolved and particulate metal concentrations in the water column of a Galician ria. Typical concentrations of dissolved Cd (96 ± 31 pM), Cu (8 ± 4 nM), Pb (270 ± 170 pM) and Zn (21 ± 10 nM) were similar than in other European Atlantic shelf and coastal waters. The fraction of metals in the particulate phase followed the trend: Pb > Cu ∼ Zn > Cd. The outgoing water from the ria was enriched in dissolved and particulate Cu, Pb and Zn compared with incoming waters, whereas Cd concentrations were similar for both waters. The suspended particulate matter was composed of a mixture of marine and continental material. The latter end-member was found to arise from the metal-rich ria bed sediments, which is diluted by the dominant metal-poor marine end-member. The net output flux of Cu from the channel is balanced by the freshwater inputs to the ria, and the net Zn flux gave a positive output to coastal waters. For Pb, the net flux to the coastal waters is less than that input from the rivers, as a result of its particle reactivity and deposition in sediments. On the contrary, a net input flux of dissolved Cd from coastal waters was observed, highlighting the oceanic source of this metal in the Galician rias. Results from the budget calculations are in agreement with the differential geochemical behavior of these elements in coastal waters.