Southern Atlantic Coast Research Articles

Radiocarbon Dating of Marine Shells from the Gulf of Cadiz: The marine radiocarbon reservoir effect, its variability during the Holocene and palaeoenvironmental inferences.

The ocean reservoir is deficient in radiocarbon compared with the atmosphere and, consequently, an offset in 14C age exists between coeval samples containing marine carbon versus those containing terrestrial carbon. A record of past reservoir ages is preserved in the 14C ages of contemporary marine and terrestrial material. The quantification of the marine radiocarbon reservoir effect (ΔR) is of crucial importance to the correct calibration of the 14C ages of marine samples. For the southern Atlantic Iberian coast, for the last 3000 yr, ΔR takes the following values +69±17 14C yr (Barlavento coast), -26±14 14C yr (Sotavento coast), and -108±31 14C yr (Andalusian coast), which are in accordance with the oceanographic conditions present in each area. Results also suggest that during the 5th millennium cal BP very different oceanographic conditions (high positive ΔR values) prevail in the Barlavento and in the Atlantic Andalusian coastal areas and, consequently, in all the northern Gulf of Cadiz region, perhaps due to the extension of the Azores Front eastward along the Azores Current penetrating into the Gulf of Cadiz.

Geographic variation in plant community structure of salt marshes: species, functional and phylogenetic perspectives.

In general, community similarity is thought to decay with distance; however, this view may be complicated by the relative roles of different ecological processes at different geographical scales, and by the compositional perspective (e.g. species, functional group and phylogenetic lineage) used. Coastal salt marshes are widely distributed worldwide, but no studies have explicitly examined variation in salt marsh plant community composition across geographical scales, and from species, functional and phylogenetic perspectives. Based on studies in other ecosystems, we hypothesized that, in coastal salt marshes, community turnover would be more rapid at local versus larger geographical scales; and that community turnover patterns would diverge among compositional perspectives, with a greater distance decay at the species level than at the functional or phylogenetic levels. We tested these hypotheses in salt marshes of two regions: The southern Atlantic and Gulf Coasts of the United States. We examined the characteristics of plant community composition at each salt marsh site, how community similarity decayed with distance within individual salt marshes versus among sites in each region, and how community similarity differed among regions, using species, functional and phylogenetic perspectives. We found that results from the three compositional perspectives generally showed similar patterns: there was strong variation in community composition within individual salt marsh sites across elevation; in contrast, community similarity decayed with distance four to five orders of magnitude more slowly across sites within each region. Overall, community dissimilarity of salt marshes was lowest on the southern Atlantic Coast, intermediate on the Gulf Coast, and highest between the two regions. Our results indicated that local gradients are relatively more important than regional processes in structuring coastal salt marsh communities. Our results also suggested that in ecosystems with low species diversity, functional and phylogenetic approaches may not provide additional insight over a species-based approach.

Seasonal patterns and trends of fastest 2‐min winds at coastal stations in the conterminous USA

ABSTRACTWeather extremes have a substantial societal impact, particularly in increasingly densely populated coastal areas. This research uses ‘fastest 2‐min wind’ records at land‐based coastal automated weather stations in the conterminous United States to characterize seasonal patterns of ‘extreme’ wind speed. The records also are examined for evidence of trends in the fastest winds that may be indicative of changes in cyclone activity over the available period of record (13–19 years).Fastest 2‐min winds at stations along the Pacific, western Gulf, and northern Atlantic coasts have a winter maximum and a summer minimum, similar to the seasonal variation in mean wind speeds. In contrast, the fastest winds at southern Atlantic and eastern Gulf coast stations show a winter minimum and a summer maximum that is opposite what is observed for mean speeds. Over the period of available record, many coastal stations show positive trends in the fastest 2‐min wind speeds in winter, spring and summer. Negative trends are most frequent in the autumn. On an annual basis, the trends in fastest 2‐min winds are consistent with the results of satellite‐derived near‐coastal oceanic wind speed assessments. Examination of daily weather maps and synoptic composites supports the interpretation that extratropical cyclone activity is the primary driver of the fastest wind speeds at most stations, with tropical systems and mesoscale features such as thunderstorms producing some of the fastest winds during the summer and autumn.

A Molecular and Morphological Study of CorallinaSensu lato(Corallinales, Rhodophyta) in the Atlantic Iberian Peninsula

DNA barcodes and morphological observation were used to evaluate the number of species within the genus Corallina sensu lato in Atlantic Iberia and to identify a set of morphological characters that may discriminate them. Five species were detected: (i) C. officinalis, (ii) C. caespitosa, (iii) Ellisolandia elongata, (iv) Corallina sp. 1, and (v) Corallina sp. 2. The first three species were widespread whereas Corallina sp. 1 was only detected in southern Atlantic coasts of Iberia and Corallina sp. 2 occurred both in the Atlantic and the Mediterranean, nevertheless, with morphological and molecular differences. The widespread occurrence of the recently described C. caespitosa along Atlantic Iberia is substantiated with sequence data for the first time; it spans from the Bay of Biscay to Andalusia and the French Mediterranean. Molecular support is also provided for the presence of C. officinalis and E. elongata in Atlantic Iberia. Plants of C. officinalis were correctly identified attending to their external morphology, however two distinct species were detected under the two forms of C. elongata (“typical” and “elongated”) reported for Galicia in the literature (C. caespitosa and Ellisolandia elongata, respectively). Plant size, habit, branching, and shape of intergenicula seem the most informative morphological characters to discriminate among the various members of Corallina s.l. in Atlantic Iberia.

Ultrastructure and phylogeny of the parasite Henneguya carolina sp. nov. (Myxozoa), from the marine fish Trachinotus carolinus in Brazil.

Microscopic and molecular procedures are used to describe a new myxosporean species, Henneguya carolina sp. nov., found infecting the intestine of the marine teleost fish Trachinotus carolinus on the southern Atlantic coast of Brazil. Spherical to ellipsoid cysts, measuring up to ~750 µm, display synchronous development. Mature myxospores are ellipsoidal with a bifurcated caudal process. Myxospore body length, width, and thickness are 12.7 ± 0.8 (12.0-13.4) µm, 8.8 ± 0.6 (7.5-9.6) µm, and 5.8 ± 0.4 (5.0-6.4) µm, respectively; 2 equal caudal processes are 16.8 ± 1.1 (15.9-18.0) µm long, and the total myxospore length is 29.4 ± 0.8 (28.4-30.4) µm. Two pyriform polar capsules measure 5.0 ± 0.5 (4.6-5.6) × 2.4 ± 0.4 (1.9-2.9) µm, and each contains a polar filament forming 3 to 4 coils. Sporoplasm is binucleated and presents a spherical vacuole surrounded by numerous globular sporoplasmosomes. Molecular analysis of the small subunit rRNA gene by maximum parsimony, neighbor joining, and maximum likelihood reveals the parasite clustering together with other myxobolids that are histozoic in marine fish of the order Perciformes, thereby strengthening the contention that the host phylogenetic relationships and aquatic environment are the strongest evolutionary signal for myxosporeans of the family Myxobolidae.

A Parameter for Forecasting Tornadoes Associated with Landfalling Tropical Cyclones

Abstract The authors develop a statistical guidance product, the tropical cyclone tornado parameter (TCTP), for forecasting the probability of one or more tornadoes during a 6-h period that are associated with landfalling tropical cyclones affecting the coastal Gulf of Mexico and the southern Atlantic coast. TCTP is designed to aid forecasters in a time-limited environment. TCTP provides a “quick look” at regions where forecasters can then conduct detailed analyses. The pool of potential predictors included tornado reports and tropical cyclone data between 2000 and 2008, as well as storm environmental parameters. The original pool of 28 potential predictors is reduced to six using stepwise regression and logistic regression. These six predictors are 0–3-km wind shear, 0–3-km storm relative helicity, azimuth angle of the tornado report from the tropical cyclone, distance from the cyclone’s center, time of day, and 950–1000-hPa convective available potential energy. Mean Brier scores and Brier skill scores are computed for the entire TCTP-dependent dataset and for corresponding forecasts produced by the Storm Prediction Center (SPC). TCTP then is applied to four individual cyclone cases to qualitatively and quantitatively assess the parameter and compare its performance with SPC forecasts. Results show that TCTP has skill at identifying regions of tornado potential. However, tornadoes in some tropical systems are overpredicted, but underpredicted in others. TCTP 6-h forecast periods provide slightly poorer statistical performance than the 1-day tornado probability forecasts from SPC, probably because the SPC product includes forecaster guidance and because their forecasts are valid for longer periods (24 h).

Change in hailstone size distributions with an increase in the melting level height

In France, the melting level height varies, during the hail season, from about 1km in the spring to more than 4km in the summer, and this parameter appears to have a connection with the mean characteristics of hailfalls. In fact, a large 25-year sample of hail size distribution measurements, made with hailpad networks along the southern Atlantic coast, reveals strong correlations between the melting level height and the mean hailstone number in different hailstone diameter ranges. On average, an increase in the melting level height is associated with a decrease in the number of small hailstones (5 to 7mm diameter), has no apparent effect in the middle range (7 to 9mm), and is concomitant with an increase in the number of larger hailstones, particularly in the 11 to 21mm ranges. When the relationships giving the hailstone number in each diameter range as a function of the melting level height are applied to a given hailfall, an increase in the melting level height is then found to go together with changes in the total hailstone number and kinetic energy. From this observation, it is possible to estimate the potential effect of global warming on hailfalls with different hailstone size distributions. The trends in the monthly surface temperature and in the hail day melting level height observed at Bordeaux during the 1988–2012 period and the global warming projections made for the present century suggest that an increase in the melting level height of 500m is forecast to occur in this region between 2000 and 2040. The consequences of such an increase for a standard hailfall in the region will be a slight decrease (−12%) in the total number of hailstones, and a significant increase (40%) in total kinetic energy, but with no significant change in the hail frequency. This analysis is compared to the already observed increase in hail intensity in the area under study, and to observations, measurements, and numerical models in other parts of the world.

Diversity, environmental requirements, and biogeography of bivalve wood-borers (Teredinidae) in European coastal waters.

BackgroundBivalve teredinids inflict great destruction to wooden maritime structures. Yet no comprehensive study was ever carried out on these organisms in European coastal waters. Thus, the aims of this study were to: investigate the diversity of teredinids in European coastal waters; map their past and recent distributions to detect range expansion or contraction; determine salinity-temperature (S-T) requirements of species; flag, for future monitoring, the species that pose the greatest hazard for wooden structures.ResultsA total of nine teredinid species were found established in European coastal waters. Seven were considered cryptogenic, of unknown origin, and two were considered alien species. Teredo navalis and Nototeredo norvagica were the species with the widest distribution in European waters. Recently, T. navalis has been reported occurring further east in the Baltic Sea but it was not found at a number of sites on the Atlantic coast of southern Europe. The Atlantic lineage of Lyrodus pedicellatus was the dominant teredinid in the southern Atlantic coast of Europe. In the Mediterranean six teredinid species occurred in sympatry, whereas only three of these occurred in the Black Sea. The species that pose the greatest hazard to wooden maritime structures in European coastal areas are T. navalis and the two lineages of L. pedicellatus.ConclusionsCombined data from field surveys and from the literature made it possible to determine the diversity of established teredinid species and their past and recent distribution in Europe. The environmental requirements of species, determined using climatic envelopes, produced valuable information that assisted on the explanation of species distribution. In addition, the observed trends of species range extension or contraction in Teredo navalis and in the two lineages of Lyrodus pedicellatus seem to emphasise the importance of temperature and salinity as determinants of the distribution of teredinids, whereas their life history strategy seems to play an important role on competition.Teredo navalis and pedicellatus-like Lyrodus species should be monitored due to their destructive capability. The two alien species may expand further their distribution range in Europe, becoming invasive, and should also be monitored.

Effect of seasonality on oxidative stress responses and metal accumulation in soft tissues of Aulacomya atra, a mussel from the South Atlantic Patagonian coast

This study investigated the effects of pollution and its interaction with temperature on the oxidative status of the ribbed mussel Aulacomya atra in the southern Atlantic Patagonian coast. Animals were collected from four sites with different degree and type of human activity impact, during the summer and winter of 2011. Seawater chromium, copper, manganese, nickel and zinc concentrations were measured, as well as metal accumulation, lipid peroxidation, protein oxidation, reduced glutathione levels, and enzymatic activities of superoxide dismutase and glutathione-S-transferase in gills and digestive glands.Metal bioaccumulation and oxidative stress responses in both tissues were generally higher in mussels from harbor areas. Water temperature had a remarkable effect on gill SOD activity and protein oxidation during winter in mussels from all locations.Methodologically, we conclude that measuring both metal bioaccumulation and oxidative stress responses allowed for a more accurate assessment of the biological effects of metal present in seawater.

‘… Latin America without the downside’: racial exceptionalism and global tourism in Costa Rica

In this paper I address how the ideology of Costa Rican exceptionalism and whiteness has maintained racial inequality with the growth of global tourism. Whereas scholars of whiteness in Latin America typically ignore how the ideology has supported racial inequality in structural forms, I explore how discursive racial discourses influence how structural inequality practices in the tourism industry take form. I examine the narratives and symbols from public and private Costa Rican tourism actors who use Costa Rica's racial ideology of exceptionalism and whiteness to position the nation's cultural wealth. Two narratives to define Costa Rica are promoted: (1) environmental uniqueness; and (2) rural democracy traditions. These narratives support white inclusionary and black exclusionary practices in tourism economic activity. Because Costa Rica is perceived as ‘white’ and represents a ‘white habitus’, it distinguishes itself as a ‘democratic’ and ‘safe’ place to visit, while negatively racialized Afro-Costa Rican locations in the southern Atlantic coast are framed as ‘dangerous’ or ‘different’ and non-representative of the exceptional characteristics.

Hydrodynamic regulation of salt marsh contributions to aquatic food webs

Vegetated salt marsh habitats are widely considered critical for supporting many species of nekton, yet direct evidence of the processes controlling marsh habitat use for most species remains elusive. We related salt marsh flooding patterns and nekton trophic dynamics among 14 sites spanning 2500 km across the northern Gulf of Mexico (GoM) and southern Atlantic coasts of the USA. Functional access for nekton to marsh vegetation (edge flooded to ≥5 cm depth) ranged from 90% access in the western GoM and Pamlico Sound. Food web mixing models based on stable isotope analysis show that the impor- tance of Spartina trophic support for common nekton may be regulated by the duration of marsh surface flooding. In particular, the potential contribution of Spartina production was positively related to indices of marsh surface flooding for brown shrimp Farfantepenaeus aztecus, white shrimp Litopenaeus setiferus, small (≤60 mm carapace width) blue crabs Callinectes sapidus, grass shrimp Palaemonetes pugio, and killifish Fundulus heteroclitus/grandis. The value of Spartina salt marsh production to several common species of nekton appears to depend, at least in part, on direct access to the vegetated marsh surface, which is regulated by hydrodynamics. Hence, the substantial geographic and temporal variability in marsh flooding regulates the func- tional roles and value of these tidal wetlands for aquatic organisms.

Concentrations and distributions of metals in tissues of stranded green sea turtles (Chelonia mydas) from the southern Atlantic coast of Brazil

Silver (Ag), cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn) concentrations were analyzed in tissues of juvenile green sea turtles (Chelonia mydas) found stranded along the southern Atlantic coast in Brazil. Green sea turtles were collected (n=29), measured (curved carapace length: CCL) and had their muscle, liver, and kidney dissected for metal concentration measurements. Sex was identified in 18 individuals (10 females and 8 males) through gonad histology. No gender differences in CCL and tissue metal concentrations were observed. In the muscle, there was a negative correlation between CCL and Cd and Cu concentrations. Metal concentrations were lower in the muscle than in the liver and kidney. Zn concentration in the muscle was the highest of all metals analyzed (16.6mg/kg). The kidney showed the highest concentrations of Pb, Cd and Zn (5.4, 28.3 and 54.3mg/kg, respectively), while the liver had the highest values of Ag and Cu (0.8 and 100.9mg/kg, respectively). Tissue Ag, Zn and Cd concentrations were similar to those found in green sea turtles from other regions while Cu and Pb values were elevated, likely due to the metal-rich water and sediment reported in the collection area. In the liver and kidney, concentrations of non-essential (Ag, Cd and Pb) and essential (Cu or Zn) metals were positively correlated, likely due to an induced metallothionein synthesis to protect tissue against the toxic effect of metals. This is the first study to report and correlate the concentrations of essential and non-essential metals in tissues of green sea turtles in the Brazilian southern Atlantic coast, an important feeding and developing area for this turtle species.

Investigation of toxin profile of Mediterranean and Atlantic strains of Ostreopsis cf. siamensis (Dinophyceae) by liquid chromatography–high resolution mass spectrometry

Blooms of Ostreopsis spp. once confined to tropical and subtropical areas have recently spread to more temperate regions such as the Mediterranean and the Southern-Atlantic coasts of Europe. However, while O. confronta (cf.) ovata has caused several toxic outbreaks, the presence of O. cf. siamensis has been reported rather occasionally and in very few regions; as a consequence, O. cf. ovata toxin profile has been in-depth studied while poor information exists on toxicity of the Mediterranean and Atlantic O. cf. siamensis. In the present study toxin profile of Mediterranean and Atlantic O. cf. siamensis isolates also phylogenetically related has been studied through liquid chromatography–high resolution mass spectrometry (LC–HRMS) versus a palytoxin standard, a crude extract of O. cf. ovata containing all the ovatoxins so far known (ovatoxin-a to -f), and a Japanese O. siamensis extract which contained ostreocin-d and ostreocin-b. The Mediterranean and Atlantic O. cf. siamensis strains were shown not to produce either ostreocins, which are produced by the Japanese O. siamensis strain, or ovatoxins, which are produced by the Mediterranean O. cf. ovata. Only sub-fg levels of palytoxin on a per cell basis were detected in the Mediterranean strain. This study demonstrates that the Mediterranean and the Atlantic O. cf. siamensis strains are devoid of any appreciable toxicity. Thus, at least in the European area, O. cf. siamensis seems to present a much lower risk to human health than O. cf. ovata.

Fish composition and assemblage in the anthropogenic-modified tidally-restricted Doñana (Spain) marshlands

The Guadalquivir estuary is the largest estuarine area on the southern Atlantic coast of Europe; its anthropogenic tidally-restricted marshes are partly within the boundary of the Doñana National Park, southern Spain. Our two-year study describes the spatial and temporal patterns of the fish assemblages in the Doñana marshlands in terms of species richness, abundance and biomass. The main families were Mugilidae and Cyprinidae, which accounted for 40.9% of the total species richness. Unlike the fish assemblages found in other European estuaries, Doñana was dominated in both biomass and abundance by freshwater species, mainly invasive exotic species. The spatial analysis of the assemblage showed four significant fish groups corresponding to different habitats established a priori and related to the salinity gradient. Assemblages did not show a seasonal pattern and the temporal fish groups observed were mainly related to the hydrological cycle and the extreme drought that occurred during the study period.

Spatial forecasting of switchgrass productivity under current and future climate change scenarios

Evaluating the potential of alternative energy crops across large geographic regions, as well as over time, is a necessary component to determining if biofuel production is feasible and sustainable in the face of growing production demands and climatic change. Switchgrass (Panicum virgatum L.), a native perennial herbaceous grass, is a promising candidate for cellulosic feedstock production. In this study, current and future (from 2080 to 2090) productivity is estimated across the central and eastern United States using ALMANAC, a mechanistic model that simulates plant growth over time. The ALMANAC model was parameterized for representative ecotypes of switchgrass. Our results indicate substantial variation in switchgrass productivity both within regions and over time. States along the Gulf Coast, southern Atlantic Coast, and in the East North Central Midwest have the highest current biomass potential. However, these areas also contain critical wetland habitat necessary for the maintenance of biodiversity and agricultural lands necessary for food production. The southern United States is predicted to have the largest decrease in future biomass production. The Great Plains are expected to experience large increases in productivity by 2080-2090 due to climate change. In general, regions where future temperature and precipitation are predicted to increase are also where larger future biomass production is expected. In contrast, regions that show a future decrease in precipitation are associated with smaller future biomass production. Switchgrass appears to be a promising biofuel crop for the central and eastern United States, with local biomass predicted to be high (>10 Mg/ha) for approximately 50% of the area studied for each climate scenario. In order to minimize land conversion and loss of biodiversity, areas that currently have and maintain high productivity under climate change should be targeted for their long-term growth potential.

Distribution du phytoplancton dans les zones d’upwelling de la côte atlantique marocaine située entre les latitudes 32°30′N et 24°N

Marine phytoplankton was studied in January and July 2002 along of four transects: 32°30′N, 29°N, 24°30′N and 24°N. A total of 142 taxa were recorded in this area. The maximal specific richness, both in summer and in winter, was registered around Dakhla (24°N). The global spatiotemporal variability of species richness and specific diversity showed that the most structured and species-rich populations are situated in the coastal areas. The vertical variation of the two parameters showed homogeneity between depth levels. The maximal phytoplanktonic densities are recorded in the southern transects due to the permanent upwelling activity in the southern Atlantic coast. The bathymetric distribution of densities was more heterogeneous during summer, characterized by a high intensity of upwelling. The species Thalassionema nitzschioides, Asterionellopsis glacialis, Melosira, Chaetoceros and Leptocylindrus minimus are indicators of upwelling.

The symbiotic hesionid Parasyllidea humesi Pettibone, 1961 (Annelida: Polychaeta) hosted by Scrobicularia plana (da Costa, 1778) (Mollusca: Bivalvia: Semelidade) in European waters

Heretofore, the hesionid polychaete Parasyllidea humesi was only known from its original description, living in association with the bivalve Tellina nymphalis in mangrove swamps north of Pointe-Noire (Republic of Congo, West Africa). The discovery of a stable population in Rio San Pedro (Gulf of Cadiz, southern Atlantic coast of Iberian Peninsula) thus represents the second report for this species worldwide, and the first for European waters. Furthermore, the new population is associated with another bivalve, Scrobicularia plana. The host-symbiont relationship is characterized by a high host-specificity (the symbiont was absent from Ruditapes decussatus and Cerastoderma glaucum collected in the same habitat and location), regular distribution (one, exceptionally two symbionts per host and then being male and female), and prevalence ranging from 0.22 % (in Cano Sancti Petri) to 4.74 % (Rio San Pedro). The symbionts seem to affect the metabolism of their hosts and, thus, their normal growth, so this association may tentatively be considered as close to parasitism. Parasyllidea humesi seems to be restricted to salt marsh areas with stable marine salinities all over the year. As there is no evidence that the presence of P. humesi in the Gulf of Cadiz results from an introduction, we strongly suggest that it may be better considered as native to the region, with our finding representing the northernmost known geographical limit of its distribution.

Morphology and molecules on opposite sides of the diversity gradient: Four cryptic species of the Clionacelata (Porifera, Demospongiae) complex in South America revealed by mitochondrial and nuclear markers

A great number of marine organisms lack proper morphologic characters for identification and species description. This could promote a wide distributional pattern for a species morphotype, potentially generating many morphologically similar albeit evolutionarily independent worldwide lineages. This work aimed to estimate the genetic variation of South America populations of the Cliona celata species complex. We used COI mtDNA and ITS rDNA as molecular markers and tylostyle length and width as morphological characters to try to distinguish among species. Four distinct clades were found within the South American C. celata complex using both genetic markers. The genetic distances comparisons revealed that scores among those clades were comparable to distances between each clade and series of previously described clionaid species, some of which belong to different genera. Our results also suggest that one of the clades has a broad discontinuous distribution in the Atlantic Ocean, while another presents high gene flow between the southern Atlantic and Pacific coasts of South America. Conversely, spicule morphology was not able to distinguish each clade, due to the high degree of overlap among them. Therefore, we considered that each recovered clade correspond, in fact, to different species that cannot be differentiated via morphological characters, which are often used to describe species within the C. celata species complex.

Mapping QTL Controlling Southern Leaf Blight Resistance by Joint Analysis of Three Related Recombinant Inbred Line Populations

ABSTRACTSouthern leaf blight (SLB) is a foliar necrotrophic disease of maize (Zea mays L.) caused by the ascomycete fungus Cochliobolus heterostrophus (Drechs.) Drechs. It is particularly important in warm humid parts of the world where maize is cultivated, such as the southern Atlantic coast area of the United States and parts of India, Africa, and Western Europe. Quantitative trait loci (QTL) for resistance to SLB disease caused by C. heterostrophus race O were identified in three maize recombinant inbred populations assessed in two environments: Clayton, NC, in the summer and Homestead, FL, in the winter. The three populations were derived from the crosses B73 × CML254, CML254 × B97, and B97 × Ki14. Each of these populations was derived from a cross between a temperate maize line (B73 or B97) and a tropical maize line (Ki14 or CML254). Quantitative trait loci were identified by separate analysis of each population and by joint connected and disconnected analyses of all the populations. The most significant QTL identified were on chromosomes 3, 8, 9,and 10. Joint analysis led to more precise position estimates than separate analysis in each case. Results are discussed in the context of previous SLB QTL analysis studies and a recent flowering time QTL study that used the same populations. The chromosome 8 and 9 QTL colocalized with previously identified flowering time QTL which suggested that the perceived effect on SLB resistance at these QTL may have been mediated through an effect on flowering time

Diarrhetic shellfish poisoning toxin profile of shellfish from Southern Atlantic coasts of Morocco

During the monitoring program of phycotoxins conducted in 2005 and 2006, lipophilic shell fish toxins (LSTs) are involved in shellfish toxicity phenomena in the South Atlantic Moroccan coasts (Dakhla region). Toxicity was assessed by the traditional mouse bioassay (MBA); the content and the nature of the toxic components were established through Liquid chromatography (LC) coupled with mass spectrometry (MS). The ‘traditional’ DSP toxins group, okadaic acid (OA) and dinophysitoxins (DTXs) and their associated esters were exclusives contaminants of Dakhla’s shellfish (mussels, cockles, oysters and solen). Pectenotoxins, yessotoxins, and azaspiracids were not detected during this study. A survey of the phytoplankton community in the surrounding seawater revealed the presence of several potentially toxic species from the Dinophysis genus.