Conquered from the Deep Sea? A New Deep-Sea Isopod Species from the Antarctic Shelf Shows Pattern of Recent Colonization

The Amundsen Sea, Antarctica, is amongst the most rapidly changing environments of the world. Its benthic inhabitants are barely known and the BIOPEARL 2 project was one of the first to biologically explore this region. Collected during this expedition, Macrostylis roaldi sp. nov. is described as the first isopod discovered on the Amundsen-Sea shelf. Amongst many characteristic features, the most obvious characters unique for M. roaldi are the rather short pleotelson and short operculum as well as the trapezoid shape of the pleotelson in adult males. We used DNA barcodes (COI) and additional mitochondrial markers (12S, 16S) to reciprocally illuminate morphological results and nucleotide variability. In contrast to many other deep-sea isopods, this species is common and shows a wide distribution. Its range spreads from Pine Island Bay at inner shelf right to the shelf break and across 1,000 m bathymetrically. Its gene pool is homogenized across space and depth. This is indicative for a genetic bottleneck or a recent colonization history. Our results suggest further that migratory or dispersal capabilities of some species of brooding macrobenthos have been underestimated. This might be relevant for the species’ potential to cope with effects of climate change. To determine where this species could have survived the last glacial period, alternative refuge possibilities are discussed.     

Do Larval Supply and Recruitment Vary among Chemosynthetic Environments of the Deep Sea?

Background

The biological communities that inhabit chemosynthetic environments exist in an ephemeral and patchily distributed habitat with unique physicochemical properties that lead to high endemicity. Consequently, the maintenance and recovery from perturbation of the populations in these habitats is, arguably, mainly regulated by larval supply and recruitment.

Methodology/Principal Findings

We use data from the published scientific literature to: (1) compare the magnitudes of and variability in larval supply and settlement and recruitment at hydrothermal vents, seeps, and whale, wood and kelp falls; (2) explore factors that affect these life history processes, when information is available; and (3) explore taxonomic affinities in the recruit assemblages of the different chemosynthetic habitats, using multivariate statistical techniques. Larval supply at vents can vary across segments by several orders of magnitude for gastropods; for bivalves, supply is similar at vents on different segments, and at cold seeps. The limited information on larval development suggests that dispersal potential may be highest for molluscs from cold seeps, intermediate for siboglinids at vents and lowest for the whale-bone siboglinid Osedax. Settlement is poorly studied and only at vents and seeps, but tends to be highest near an active source of emanating fluid in both habitats. Rate of recruitment at vents is more variable among studies within a segment than among segments. Across different chemosynthetic habitats, recruitment rate of bivalves is much more variable than that of gastropods and polychaetes. Total recruitment rate ranges only between 0.1 and 1 ind dm⁻² d⁻¹ across all chemosynthetic habitats, falling above rates in the non-reducing deep sea. The recruit assemblages at vents, seeps and kelp falls have lower taxonomic breadth, and include more families and genera that have many species more closely related to each other than those at whale and wood falls. Vents also have the most uneven taxonomic structure, with fewer recruits represented by higher taxonomic levels (phyla, orders, classes) compared to seeps and wood and kelp falls, whereas the opposite is true at whale falls.

Conclusions/Significance

Based on our evaluation of the literature, the patterns and regulatory factors of the early history processes in chemosynthetic environments in the deep sea remain poorly understood. More research focused on these early life history stages will allow us to make inferences about the ecological and biogeographic linkages among the reducing habitats in the deep sea.     

Microbial community composition of anoxic marine sediments in the Bay of Cádiz (Spain)

The composition of the microbial community inhabiting the anoxic coastal sediments of the Bay of Cádiz (southern Spain) was investigated using a molecular approach consisting of PCR cloning and denaturing gradient gel electrophoresis (DGGE), based on 16S rRNA sequences. The total cell count was 1-5 × 10? cells/g sediment and, as determined by catalyzed reporter deposition-fluorescent in situ hybridization (CARD-FISH), the proportion of Bacteria to Archaea was about 70:30. The analysis of 16S-rRNA gene sequences revealed a wide spectrum of microorganisms, which could be grouped into 111 operational taxonomic units (OTUs). Many of the OTUs showed high phylogenetic similarity to microorganisms living in marine sediments of diverse geographic origin. The phylogenetic groups that were predominantly detected were Firmicutes, Deltaproteobacteria, and Gammaproteobacteria, accounting for 23, 15, and 14% of the clones, respectively. Diversity in the domain Archaea was significantly lower than in the domain Bacteria. The majority of the archaeal OTUs belonged to the Crenarchaeota phylum. Since most of the sequences could not be identified precisely at the genus/species level, the functional roles of the microorganisms in the ecosystem could not be inferred. However, seven OTUs affiliated with the Delta- and Epsilonproteobacteria were identified down to the genus level, with all of the identified genera known to occur in sulfate-rich marine environments.     

Are Bacteria the Major Producers of Extracellular Glycolytic Enzymes in Aquatic Environments?

In aquatic microbial ecology, it has been considered that most extracellular enzymes except phosphatases are of bacterial origin. We tested this paradigm by evaluating the relationship between bacterial cell number and the activity of three glycolytic enzymes from 17 fresh waters and also from a laboratory experiment. Our large sets of pooled data do not seem to support such a simple explanation, because we found only a weak correlation of bacterial number with activity of α‐glucosidase (r_s = 0.63), β‐glucosidase (r_s = 0.45), and β‐N‐acetylhexosaminidase (r_s = 0.44). We also tested relations of the enzymatic activities to potential sources of natural substrates: dissolved organic carbon (DOC) and phytoplankton (as chlorophyll a). Their correlations with the enzymatic activities tested were very weak or insignificant. On the other hand, we found evidence for distinct producers of extracellular enzymes by analysing enzyme kinetics. The kinetics usually did not follow the simple Michaelis‐Menten model but a more complex one, indicating a mixture of two enzymes with distinct affinity to a substrate. In combination with size fractionation, we could sometimes even distinguish three or more different enzymes. During diatom blooms, the diatom biomass tightly correlated with β‐N‐acetylhexosaminidase activity (>4 μm fraction). We also documented very tight relationships between activity of both glucosidases and dry weight of Daphnia longispina (r_s = 1.0 and 0.60 for α‐ and β‐glucosidases, respectively) in an alpine clear‐water lake. Our data and evidence from other studies indicate that extracellular glycosidic activities in aquatic ecosystems cannot generally be assigned only to bacteria. Also invertebrate animals and other eukaryotes (fungi, diatoms, protozoa etc.) should be considered as potentially very important enzyme producers. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Phylogenetic Relationships Among Ten Sole Species (Soleidae,Pleuronectiformes) from the Gulf of Cádiz (Spain) Based on Mitochondrial DNA Sequences

The entire sequence of the mitochondrial cytochrome b gene and 2 partial sequences of the ribosomal RNA12S and 16S genes have been used to study the molecular phylogeny in 10 species of soles belonging to the genera Solea, Monochirus, Microchirus, Dicologlossa, and Synaptura from the Atlantic waters of the Gulf of Cádiz (Spain). The results obtained by means of different phylogenetic analyses (maximum likelihood, maximum parsimony, and neighbor-joining) were quite similar, supporting the monophyly of the Solea species. Nevertheless, they favor the differentiation of Dicologlossa cuneata and Dicologlossa hexophthalma in 2 distinct genera, since the most closely related species to the last one is Microchirus azevia. The fact that M. azevia is also more closely linked to Monochirus hispidus than to its congeneric Microchirus boscanion argues in favor of a taxonomic reorganization of these genera.     

Are copepods important grazers of the spring phytoplankton bloom in the western Irish Sea?

The spring phytoplankton bloom and copepod grazing were studied at a coastal and offshore station in the western Irish Sea during 1997. Maximum chlorophyll standing stocks of 132.8 mg m^-2 inshore and 199.4 mg m^-2 offshore were measured in late April. At that time, mean water column temperatures were 10 and 8C at the coastal and offshore station, respectively. Spring bloom production at the coastal station was estimated as 31.2 g C m^-2 and was dominated by the diatom Guinardia delicatula. Offshore, production was 28.2 g C m^-2 and the bloom was composed of small (10 m) phytoflagellates and the silicoflagellate Dictyocha speculum. Maximum copepod abundance (189 and 544 x 10³ individuals m^-2, inshore and offshore, respectively) coincided with the spring bloom. Pseudocalanus and Temora ingestion rates were derived from measurements of gut pigment fluorescence, and were found to vary during the course of the spring bloom as a result of changes in gut content. Grazing by late copepodite and adult Pseudocalanus and Temora was variable inshore, but overall accounted for 17% of bloom production. Offshore, 22% of bloom production was grazed with maximum grazing (76% of daily production) occurring at the end of the bloom. Large copepod species were not major grazers of the spring bloom. Greater utilization of spring bloom production by copepods in the western Irish Sea compared to regions of the North Sea is attributed to differences in population size at the time of the bloom.      

Early-Onset Atopic Dermatitis in Children: Which Are the Phenotypes at Risk of Asthma? Results from the ORCA Cohort

Background

Atopic dermatitis (AD) is known to predate asthma and other atopic disorders described under the term “atopic march”. However, this classic sequence is not always present and only a few studies have addressed children at risk of developing asthma. The objective of this study is to define early-onset AD phenotypes leading to asthma.

Methods

We performed a cluster analysis with 9 variables of 214 infants with early-onset AD prospectively enrolled in the ORCA cohort and followed each year on the occurrence of asthma until the age of 6.

Results

We identified 3 clusters - cluster 1 (n = 94) with low to no sensitization to food (27.7%) or aeroallergens (10.6%) and moderate AD severity (SCORAD 25.29 +/- 14.6) called “AD with low sensitization”; - cluster 2 (n = 84) characterized by a higher AD severity (SCORAD 32.66+/-16.6) and frequent sensitization to food (98.9%) or aeroallergens (26.2%), most likely multiple (96.4% for food allergens), called “AD with multiple sensitizations” - cluster 3 (n = 36) with parental history, moderate AD severity (SCORAD 24.46+/-15.7), moderate rate of sensitization to food allergens (38.9%) (exclusively single) with no sensitization to aeroallergens, called “AD with familial history of asthma”. Percentages of children suffering from asthma at the age of 6 were higher in clusters 2 and 3 (36.1% and 33.3% respectively versus 14.9% in cluster 1, p<0.01).

Conclusion

Two phenotypes in infants with early-onset AD convey a higher risk of developing asthma during childhood: multiple sensitization and familial history of asthma.     

Do clades of symbiotic dinoflagellates in scleractinian corals of the Gulf of Eilat (Red Sea) differ from those of other coral reefs?

The symbiotic association between corals and zooxanthellae has been a major contributing factor in the success of reef-building corals. Most of these endocellular microalgal symbionts belong to the dinoflagellate genus Symbiodinium. However, considerable genetic diversity was revealed within this taxon, as is evident in the several clades of Symbiodinium found in association with hermatypic corals all over the world. The coral reefs of Eilat (Aqaba), where winter temperature minima of 21 °C are close to threshold values that prevent reef development, are among the northernmost reefs in the world. Furthermore, due to the circulation patterns of the Gulf, the extremely high evaporation, and lack of any riverine inputs, the Gulf's waters are highly saline (40.5‰). In spite of the extreme location, a high diversity of coral species has been reported in this area. In this study, using PCR, we specifically amplified zooxanthellae 18S ribosomal DNA from symbionts of 11 coral species, and analyzed it with respect to RFLP and DNA sequence.Of the several clades described from the same coral hosts in other localities, only A and C were found in the present study. Symbiodinium populations in the host examined from Eilat were different relative to other parts of the world. This distribution is discussed in relation to reproduction strategy: broadcasting versus brooding. Based on our results, we suggest that clade A is transferred through a closed system. As mass bleaching in the Gulf has never been observed, we suggest that the adaptive mechanisms presumably favoring clade diversity were not yet significant in our relatively cool area.     

Are the Rates of Hypertension and Diabetes Higher in People from Lower Socioeconomic Status in Bangladesh? Results from a Nationally Representative Survey

ObjectiveA well-established belief regarding inequalities in health around the world is that hypertension and diabetes are higher in groups of lower socioeconomic status. We examined whether rates of hypertension, diabetes, and the coexistence of hypertension and diabetes are higher in people from a lower socioeconomic status than in those from a higher socioeconomic status in Bangladesh.MethodsWe investigated a nationally representative dataset from the 2011 Bangladesh Demographic and Health Survey with objective measures for hypertension and diabetes. A wealth index was constructed from data on household assets using principal components analysis. Chi-square tests and logistic regressions were performed to test the associations between wealth level, hypertension and diabetes.FindingsPeople from the highest wealth quintile were significantly more likely to have hypertension (Adjusted odds ratios [AOR] = 1.65, 95% confidence interval [CI] = 1.22-2.25), diabetes (AOR = 1.81, 95% CI = 1.21-2.71), and the coexistence of hypertension and diabetes (AOR = 2.17, 95% CI = 1.05-4.49) than people from the lowest wealth quintile. The odds of having hypertension, diabetes, and their coexistence were higher for older people, women, people who engaged in less physical labor, and people who were overweight and obese.ConclusionWealthier people, particularly people from the fourth and highest wealth quintiles, should be careful to avoid unhealthy lifestyles to prevent hypertension and diabetes. Health policy makers and planners are urged to target wealthier strata in terms of hypertension and diabetes initiatives while paying special attention to older people, women, people who engage in less physical labor, and individuals who are overweight.     

A life in the surf zone: Age and feeding habits of the pompano (Trachinotus ovatus,Linnaeus, 1758) on the beaches of the Gulf of Cádiz (south-west Iberian Peninsula)

Surf zones are crucial habitats for many fish species, where they spend the initial stages of their lives, finding food and shelter. One such species is the pompano (Trachinotus ovatus). The aim of this study was to examine the age and diet of the pompano within the surf zone, along with any potential variations in the environment. The average size of the specimens was 10.61 ± 4.91 cm. The length–weight relationship was total weight (TW) = 0.0136*total length (TL)^2.8512 (parameter a: 95% C.I. : 0.0130–0.0142 and parameter b: 95% C.I. : 2.8318–2.8705). The most abundant age classes were 0+ and 1+, making up 97% of the captured specimens, with significant differences in the abundance of age classes depending on the time of the day and season. The pompano primarily fed on clupeiforms, copepods, and mysids, with significant variations in diet based on the time of the day, season, and size of the specimens. This study contributes new information about the use of the surf zone by T. ovatus in its early years of life, underscoring the importance of these areas and their role as an additional ecosystem service.     

Profiles of Organic Food Consumers in a Large Sample of French Adults: Results from the Nutrinet-Santé Cohort Study

Background

Lifestyle, dietary patterns and nutritional status of organic food consumers have rarely been described, while interest for a sustainable diet is markedly increasing.

Methods

Consumer attitude and frequency of use of 18 organic products were assessed in 54,311 adult participants in the Nutrinet-Santé cohort. Cluster analysis was performed to identify behaviors associated with organic product consumption. Socio-demographic characteristics, food consumption and nutrient intake across clusters are provided. Cross-sectional association with overweight/obesity was estimated using polytomous logistic regression.

Results

Five clusters were identified: 3 clusters of non-consumers whose reasons differed, occasional (OCOP, 51%) and regular (RCOP, 14%) organic product consumers. RCOP were more highly educated and physically active than other clusters. They also exhibited dietary patterns that included more plant foods and less sweet and alcoholic beverages, processed meat or milk. Their nutrient intake profiles (fatty acids, most minerals and vitamins, fibers) were healthier and they more closely adhered to dietary guidelines. In multivariate models (after accounting for confounders, including level of adherence to nutritional guidelines), compared to those not interested in organic products, RCOP participants showed a markedly lower probability of overweight (excluding obesity) (25≤body mass index<30) and obesity (body mass index ≥30): −36% and −62% in men and −42% and −48% in women, respectively (P<0.0001). OCOP participants (%) generally showed intermediate figures.

Conclusions

Regular consumers of organic products, a sizeable group in our sample, exhibit specific socio-demographic characteristics, and an overall healthy profile which should be accounted for in further studies analyzing organic food intake and health markers.     

Distribution and production ofChironomus salinarius (Diptera: Chironomidae) in a shallow coastal lagoon in the Bay of Cádiz

The abundance, generation time and production ofChironomus salinarius larvae in a lagoon fish-pond system in the Bay of Cádiz were studied by taking monthly samples at 3 sites during 1991 and 1992. Numerical abundance and biomass of larvae showed considerable spatial, seasonal and interannual variation (ANCOVAs,P<0.001). The maximum mean annual density was 7048 larvae m^–2, and corresponded to a biomass of 3.08 g dry weight (DW) m^–2. It was recorded at the site with the lowest rate of water renewal. Seasonal patterns were similar at all sites, with main annual peaks of abundance and biomass in autumn-early winter. Chironomid density was positively related to the biomass of benthic macroalgae (P<0.001). The population studied was multivoltine with a probable average of five generations per year, with overlapping cohorts and a predominance of third- and fourth-instar larvae. Estimates of annual production ranged between 72.2 g DW m^–2 yr^–1 at the site with the lowest rate of water renewal in 1991 and 0.1 g DW m^–2 yr^–1 at the site with the highest rate of water renewal in 1992. Mean annual production and the production/biomass ratio for the system was estimated to be 16.8 g DW m^–2 yr^–1 and 12.7, respectively. Possible factors leading to the observed density fluctuations are discussed, as well as possible sources of error in production estimates.     

First record of the occurrence of "gill disease" in Mytilus edulis trossulus from the Gulf of Gdańsk (Baltic Sea, Poland)

We are presenting the first report of the occurrence of "gill disease" in Mytilus edulis trossulus from the southern Baltic Sea, Gulf of Gdańsk (Poland). The disease preliminary diagnosis was based on the presence of white and yellow "spots" causing deep indentations in the gills with degeneration, destruction and necrosis of gill filaments. Average prevalence of gill erosion in the blue mussels population was 15.8%. According to other authors, gill erosion may affect over 80% of the bivalve population resulting in mortality rates of up to 40%. The origin of the gill erosion remains unknown, but viruses are most likely involved in the etiology of these pathological conditions. The disease as such may indicate a decrease in the immunological resistance of organisms to infections and inflammations directly or indirectly caused by harmful factors in the ambient environment. Furthermore, the occurrence of numerous pathologies in bivalves is a particular problem in the Gulf of Gdańsk being a low biodiversity ecosystem. Pathologies reduce bilvalves' reproduction ability, worsen their physiological condition and increase their mortality rate. Those factors may also pose a significant ecological danger and lead to negative alterations of the ecosystem.     

Why Are Clinicians Not Embracing the Results from Pivotal Clinical Trials in Severe Sepsis? A Bayesian Analysis

Background

Five pivotal clinical trials (Intensive Insulin Therapy; Recombinant Human Activated Protein C [rhAPC]; Low-Tidal Volume; Low-Dose Steroid; Early Goal-Directed Therapy [EGDT]) demonstrated mortality reduction in patients with severe sepsis and expert guidelines have recommended them to clinical practice. Yet, the adoption of these therapies remains low among clinicians.

Objectives

We selected these five trials and asked: Question 1-What is the current probability that the new therapy is not better than the standard of care in my patient with severe sepsis? Question 2-What is the current probability of reducing the relative risk of death (RRR) of my patient with severe sepsis by meaningful clinical thresholds (RRR >15%; >20%; >25%)?

Methods

Bayesian methodologies were applied to this study. Odds ratio (OR) was considered for Question 1, and RRR was used for Question 2. We constructed prior distributions (enthusiastic; mild, moderate, and severe skeptic) based on various effective sample sizes of other relevant clinical trials (unfavorable evidence). Posterior distributions were calculated by combining the prior distributions and the data from pivotal trials (favorable evidence).

Main Findings

Answer 1-The analysis based on mild skeptic prior shows beneficial results with the Intensive Insulin, rhAPC, and Low-Tidal Volume trials, but not with the Low-Dose Steroid and EGDT trials. All trials'' results become unacceptable by the analyses using moderate or severe skeptic priors. Answer 2-If we aim for a RRR>15%, the mild skeptic analysis shows that the current probability of reducing death by this clinical threshold is 88% for the Intensive Insulin, 62–65% for the Low-Tidal Volume, rhAPC, EGDT trials, and 17% for the Low-Dose Steroid trial. The moderate and severe skeptic analyses show no clinically meaningful reduction in the risk of death for all trials. If we aim for a RRR >20% or >25%, all probabilities of benefits become lower independent of the degree of skepticism.

Conclusions

Our clinical threshold analysis offers a new bedside tool to be directly applied to the care of patients with severe sepsis. Our results demonstrate that the strength of evidence (statistical and clinical) is weak for all trials, particularly for the Low-Dose Steroid and EGDT trials. It is essential to replicate the results of each of these five clinical trials in confirmatory studies if we want to provide patient care based on scientifically sound evidence.     

The effect of epibenthic predators and macroalgal cover on the benthic macroinvertebrate community of a shallow lagoon in the Bay of Cádiz (SW Spain)

Three field predator exclusion experiments were conducted in 1992 on a lagoonal muddy pan of the Bay of Cádiz to measure the effects of large epibenthic predators (fish and crustacean decapods) on the benthic macroinvertebrate community at different periods of the year (May–June, August–September, November–December). At the end of each field experiment (30–31 days), benthic macrofaunal communities within exclosures and control plots (three replicates for each treatment) were compared. There were no considerable exclosure artifacts in all three experiments, but a great heterogenity in the spatial macrofaunal distribution was observed especially in the late autumn experiment. No systematic change in overall faunal characteristics was observed with the exclusion of epibenthic predators, except significantly greater mean individual sizes (all experiments) and lower total densities (June and December) within exclosures. For several benthic species, a statistically detectable increased density and larger mean individual size were also observed within exclosures in May–June and August–September experiments but not in December, probably related to the higher predatory activity during the warm season. Conversely, the amphipod Microdeutopus gryllotalpa showed lower density but also larger mean size when epibenthic predators were excluded. An algal cover (Ulva) was present at three field experiments and had a mixed effect on the density of benthic macrofauna. Some epifaunal species (or epifaunal stages) were positively affected by the algal biomass, while some infaunal species were negatively affected.     

Effects of fine-scale environmental heterogeneity on local genetic structure in Macoma balthica from the Gulf of Gdañsk (southern Baltic Sea)

Surveys of unionid populations have been incorporated into the Swedish national environmental monitoring program. Nevertheless there is still lack of knowledge of important aspects of the biology of many unionid species. There may also be differences between species. This work compares the spatial distribution of two unionid species, Anodonta anatina and Unio tumidus, at four sites in Sweden. Samples were taken at transects along the shoreline at different water depths on the surface bed and in the sediments. Individual mussel ages were determined. Our results indicated that younger mussel individuals do not show differences in horizontal spatial distribution compared to older mussel individuals. However, they showed a preference to be burrowed in the sediment compared to older individuals that were predominantly found at the sediment surface. We also found a large difference in burrowing frequency between species with a higher frequency of burrowed adult individuals of A. anatina than U. tumidus. This result may be due to the timing of our field survey that coincided with the period of glochidia release for U. tumidus. We can conclude that a monitoring program for freshwater mussel populations needs to be carefully planned in time.     

Connectivity across the Caribbean Sea: DNA Barcoding and Morphology Unite an Enigmatic Fish Larva from the Florida Straits with a New Species of Sea Bass from Deep Reefs off Cura?ao

Integrative taxonomy, in which multiple disciplines are combined to address questions related to biological species diversity, is a valuable tool for identifying pelagic marine fish larvae and recognizing the existence of new fish species. Here we combine data from DNA barcoding, comparative morphology, and analysis of color patterns to identify an unusual fish larva from the Florida Straits and demonstrate that it is the pelagic larval phase of a previously undescribed species of Liopropoma sea bass from deep reefs off Curaçao, southern Caribbean. The larva is unique among larvae of the teleost family Serranidae, Tribe Liopropomini, in having seven elongate dorsal-fin spines. Adults of the new species are similar to the golden bass, Liopropoma aberrans, with which they have been confused, but they are distinct genetically and morphologically. The new species differs from all other western Atlantic liopropomins in having IX, 11 dorsal-fin rays and in having a unique color pattern–most notably the predominance of yellow pigment on the dorsal portion of the trunk, a pale to white body ventrally, and yellow spots scattered across both the dorsal and ventral portions of the trunk. Exploration of deep reefs to 300 m using a manned submersible off Curaçao is resulting in the discovery of numerous new fish species, improving our genetic databases, and greatly enhancing our understanding of deep-reef fish diversity in the southern Caribbean. Oh the mother and child reunion is only a moment away. Paul Simon.     

Food supply for waders (Aves: Charadrii) in an estuarine area in the Bay of Cádiz (SW Iberian Peninsula)

We studied the composition, density, size distribution and biomass of the food supply for waders in an estuarine area in the Bay of Cádiz (SW Iberian Peninsula), in winter (January-February) and in the pre-migratory period (late March). The estuarine area comprises an intertidal mudflat and an adjacent salina or salt-pan. On the intertidal mudflat, the biomass was 53 and 37 g  AFDW.m^-2in winter and the pre-migratory period, respectively. The main food source on mudflat was the polychaete Nereis diversicolor (44–54 % of the total biomass). On the other hand, the biomass in the salina was comparatively very poor, ranging from 0.008 to 0.079 g  AFDW.m^-2in winter and ranging from 0.011 to 0.09 g AFDW in late March. The main source of food in the salina was the crustacean Artemia. The total biomass on the mudflat during the pre-migratory period was 1.4 times lower than in February. This depletion could be caused by wader predation, mainly by Nereis diversicolor consumption. Although the potential food on the mudflats could allow high intertidal densities of waders, the availability of high tide foraging areas in the salina seems to contribute to the maintenance of these high intertidal densities.