Reguera B.,Spanish Institute of Oceanography |
Riobo P.,CSIC - Institute of Marine Research |
Rodriguez F.,Spanish Institute of Oceanography |
Diaz P.A.,Spanish Institute of Oceanography |
And 5 more authors.
Marine Drugs | Year: 2014
Several Dinophysis species produce diarrhoetic toxins (okadaic acid and dinophysistoxins) and pectenotoxins, and cause gastointestinal illness, Diarrhetic Shellfish Poisoning (DSP), even at low cell densities (<10 3 cells·L-1). They are the main threat, in terms of days of harvesting bans, to aquaculture in Northern Japan, Chile, and Europe. Toxicity and toxin profiles are very variable, more between strains than species. The distribution of DSP events mirrors that of shellfish production areas that have implemented toxin regulations, otherwise misinterpreted as bacterial or viral contamination. Field observations and laboratory experiments have shown that most of the toxins produced by Dinophysis are released into the medium, raising questions about the ecological role of extracelular toxins and their potential uptake by shellfish. Shellfish contamination results from a complex balance between food selection, adsorption, species-specific enzymatic transformations, and allometric processes. Highest risk areas are those combining Dinophysis strains with high cell content of okadaates, aquaculture with predominance of mytilids (good accumulators of toxins), and consumers who frequently include mussels in their diet. Regions including pectenotoxins in their regulated phycotoxins will suffer from much longer harvesting bans and from disloyal competition with production areas where these toxins have been deregulated. © 2014 by the authors; licensee MDPI.
Andrefouet S.,IRD Montpellier |
Rilwan Y.,Marine Research Center |
Hamel M.A.,IRD Montpellier
Atoll Research Bulletin | Year: 2012
In order to propose spatially-explicit conservation strategies driven by biodiversity for Baa Atoll, habitat maps were created from LANDSAT and Quickbird satellite images. The LANDSAT derived habitat map described the atoll geomorphology following the Millennium Coral Reef Mapping Project typology, which is made of 5 different hierarchical levels. The Quickbird derived high spatial resolution habitat map is a map of both geomorphological and benthic hierarchical information. Benthic information comes from 24 field stations surveyed in May-June 2009 for this project, and from an independent survey that quantified forereef coral cover and dominant growth forms for all the reefs found in Baa Atoll in June 2008. The Quickbird derived habitat map is created to take advantage of this extensive data set, which minimizes mapping errors on forereefs. Other reef zones were also mapped by considering the hierarchical level (geomorphology and benthic if possible) that minimized photo-interpretation uncertainty. Both habitat maps were processed to display habitat richness for all virtual management units found along a regular grid (1 km 2-cell). The differences due to different spatial and thematic resolution are discussed.
Andrefouet S.,Institute Of Recherche Pour Le Developpement |
Menou J.-L.,Institute Of Recherche Pour Le Developpement |
Naeem S.,Marine Research Center
Atoll Research Bulletin | Year: 2012
In order to guide conservation efforts in Baa Atoll in the Republic of Maldives, macro-invertebrate species (principally sponges, sea stars, urchins, holothurians, crinoids, ophiuroids, ascidians, bivalves, gastropods, anemones, zooanthids, anthipatharian, gorgonians, alcyonaceans, and flatworms) were inventoried on 21 sites to provide an index of benthic species richness (number of species). A total of 182 species were recorded and identified. Richness ranged between 6 to 40 species per sampling sites. The richest sites were hard-bottom submerged lagoonal patch reefs experiencing high currents. Ecological rarity dominates the macro-invertebrate community pattern with 95 species found in only one sampling site. This new data set brings fresh knowledge on Baa Atoll and Maldives in order to identify biodiversity hot-spots. Further work will investigate the sensitivity of biodiversity conservation planning and sitting algorithms to this data set.
Barnes R.S.K.,University of Cambridge |
Barnes R.S.K.,Marine Research Center
Hydrobiologia | Year: 2010
A preliminary attempt was made to quantify the alpha diversity of fiddler crabs (Uca spp.) along a short transect across the interface between an intertidal mudflat and a largely Avicennia mangrove at Ambeua on the Indonesian island of Kaledupa in Sulawesi Tenggara, by means of visual counts within 2 m2 quadrats. An astounding diversity of up to six seemingly coexisting species per quadrat-and a total of seven such species within an area of 4 m2-was revealed. Four species of the ecologically equivalent sentinel crabs (Macrophthalmus) were also present in the quadrats. Seven fiddler crab species equates to more than half those known from Wallacea, more than one-third of all those known from Indonesia, and almost one-fifth of the entire Uca fauna of the Indo-West-Pacific. © Springer Science+Business Media B.V. 2009.
Bigot L.,University of Reunion Island |
Amir H.,Marine Research Center
Atoll Research Bulletin | Year: 2012
A survey of scleractinian corals for 21 stations in Baa Atoll (Republic of Maldives) was conducted in June 2009. The goal of the survey was to i) compile for the first time for this atoll a scleractinian coral check-list, ii) estimate the atoll total richness, iii) estimate intra-atoll richness variation and iv) describe preliminary patterns of community structure according to geomorphology and location criteria. The survey was stratified by the main reef geomorphological units. A total of 173 species of scleractinia belonging to 49 genera were recorded, including several species new to Maldives. Conversely, a number of species of genera quite common in the Indian Ocean were absent of the list of Pocilloporidae. Average richness per station was nearly 60 species. Richness ratio between slopes and flats/tops were between 3 and 1.3, with an average of 2.1, highlighting richer slopes than flats and tops. Differences of community composition between geomorphologic strata and between oceanic/lagoonal reefs were significant. Central lagoonal reefs provided highest richness, and highest coral cover as well. These findings are critical to plan for the conservation of Baa Atoll biodiversity.
El Samad O.,Lebanese Atomic Energy Commission |
Aoun M.,Lebanese Atomic Energy Commission |
Nsouli B.,Lebanese Atomic Energy Commission |
Khalaf G.,Marine Research Center |
Hamze M.,National Council for Scientific Research CNRS
Journal of Environmental Radioactivity | Year: 2014
This investigation was carried out in order to assess the marine environmental radioactive pollution and the radiological impact caused by a large production plant of phosphate fertilizer, located in the Lebanese coastal zone. Natural radionuclides (238U, 235U, 232Th, 226Ra, 210Po, 210Pb, 40K) and anthropogenic 137Cs were measured by alpha and gamma spectrometry in seawater, sediment, biota and coastal soil samples collected from the area impacted by this industry. The limited environmental monitoring program within 2km of the plant indicates localized contamination with radionuclides of the uranium decay chain mainly due to the transport, the storage of raw materials and the free release of phosphogypsum waste. © 2013 Elsevier Ltd.
Puttonen I.,Åbo Akademi University |
Mattila J.,Åbo Akademi University |
Jonsson P.,University of Stockholm |
Karlsson O.M.,IVL Swedish Environmental Reserach Institute Ltd |
And 5 more authors.
Estuarine, Coastal and Shelf Science | Year: 2014
Phosphorus contents in the sediments were determined in archipelago areas of the northern Baltic Sea (Svealand in Sweden and Åland, SW Finland and W Uusimaa in Finland) during 2008-2012. Spatial and vertical distribution of phosphorus was studied by analysing sediment samples from 345 stations of different seabed substrate types. A sequential extraction method was applied to evaluate the pool of the potentially mobile phosphorus, i.e., the amount of phosphorus that can be expected to be released from sediments to water with time, and possibly support primary production. In addition, vertical distribution of immobile phosphorus forms in the sediments was used as a tool to assess phosphorus burial. The uppermost 2cm of sediments were calculated to contain 126,000tonnes of phosphorus in the study area covering 19,200km2 of the seafloor. Subtracting the assumed average background content (i.e. that assumed to be buried) of this total phosphorus content gave an estimation of 31,000-37,000tonnes of potentially mobile phosphorus at the sediment surface. Redox sensitive iron-bound phosphorus accounts for two thirds of this pool. Compared with the total phosphorus input from the catchment of the entire Baltic Sea - 29,000 tonnes in 2009 - it can be concluded that the store of phosphorus that can be released with time from the sediments is large, and that internal phosphorus recycling processes thus may play a key role in phosphorus fluxes in the coastal zone. Spreading of hypoxia in the future, as recent modelling and sediment proxy results suggest, is likely to severely deteriorate the water quality, particularly in the archipelago areas where the water exchange is slow. © 2014 Elsevier Ltd.
Olafsdottir G.A.,University of Iceland |
Olafsdottir G.A.,Marine Research Center
Proceedings. Biological sciences / The Royal Society | Year: 2014
Atlantic cod (Gadus morhua) vertebrae from archaeological sites were used to study the history of the Icelandic Atlantic cod population in the time period of 1500-1990. Specifically, we used coalescence modelling to estimate population size and fluctuations from the sequence diversity at the cytochrome b (cytb) and Pantophysin I (PanI) loci. The models are consistent with an expanding population during the warm medieval period, large historical effective population size (NE), a marked bottleneck event at 1400-1500 and a decrease in NE in early modern times. The model results are corroborated by the reduction of haplotype and nucleotide variation over time and pairwise population distance as a significant portion of nucleotide variation partitioned across the 1550 time mark. The mean age of the historical fished stock is high in medieval times with a truncation in age in early modern times. The population size crash coincides with a period of known cooling in the North Atlantic, and we conclude that the collapse may be related to climate or climate-induced ecosystem change.
Anderson R.C.,Manta Marine Pvt Ltd. |
Adam M.S.,Marine Research Center |
Goes J.I.,Bigelow Laboratory for Ocean Sciences
Fisheries Oceanography | Year: 2011
The Republic of Maldives in the central Indian Ocean is home to large numbers of manta rays, Manta alfredi. They are known to undertake seasonal migrations within the Maldives, but these movements have not been well documented. The aims of this study were to map the seasonal distribution of manta rays within the Maldives, and to provide some indications of the physical and biological oceanographic processes affecting their distribution. The seasonal distribution of mantas was determined from a national survey of fishermen, interviews with experienced divers and personal observations. The data demonstrate that the distribution of mantas is strongly influenced by the seasonally reversing monsoon currents. Mantas occur on the downstream sides of the atolls, and are rare on the upstream sides, switching sides biannually as the monsoon currents change direction. These seasonally alternating currents are driven by monsoon winds which also alternate according to the season, and bring clear oceanic water to the upstream sides of the atolls. As the currents pass over the Maldives ridge, nutrient-rich waters are lifted to the surface, promoting phytoplankton blooms (as demonstrated by the distribution of chlorophyll-a) on the downstream sides of the atolls. This manifestation of the island mass effect supports an abundance of zooplankton, which in turn supports the manta rays. © 2011 Blackwell Publishing Ltd.
Fleming-Lehtinen V.,Marine Research Center |
Laamanen M.,Helsinki Commission
Estuarine, Coastal and Shelf Science | Year: 2012
Secchi depth, as a proxy of water transparency, provides valuable information on the availability of light to the underwater ecosystems. Changes in water transparency have also been widely linked to eutrophication and phytoplankton biomass. This study aimed to describe the development of water transparency in the Baltic Sea through a unique century-long set of Secchi depth observations. Furthermore, the aim was to explain the role of phytoplankton in determining water transparency in these optically complex waters. Water transparency in the open Baltic Sea has decreased during the last one hundred years. The development differs between the sub-basins of the Baltic Sea. The decrease has been most profound in the north-eastern Baltic sub-basins, but apparent also in parts of the Southern and Central Baltic. In many of the northern areas the decrease has accelerated during the last decades, whereas in the Southern Baltic a recent increase was observed. The analysis of simultaneous chlorophyll . a observations during the period from 1972 to 2006 revealed that during summer time, 13-17% of the light attenuation can be attributed to phytoplankton. In spring, the average proportion is between 31 and 42%, with great variation between observations. We find Secchi depth a suitable indicator of eutrophication, integrating various organic matter related features. It should always be applied with sufficient background information of the optical properties of the water mass, and complemented by other indicators. © 2012 Elsevier Ltd.