Atlantic Populations Research Articles

Movement behavior of satellite-tagged leatherback turtles from Panama in response to chlorophyll, primary productivity, temperature, and eddy kinetic energy

Leatherback turtles Dermochelys coriacea are globally endangered. This study tracked 30 individuals from the North Atlantic population tagged on the Caribbean Panama rookery (San San Pond Sak protected area, Bocas del Toro) over a period of 3 yr. We used satellite telemetry to investigate the probability that turtles switched between migration and foraging behavioral states as a function of environmental variables. We mapped the extensive migratory routes of these turtles and analyzed these using data derived from remote sensing, including chlorophyll, productivity, and sea surface temperature (SST), to assess how these influence their migratory and foraging behaviors. We also considered oceanographic processes, i.e. mesoscale eddies coinciding with the turtles’ migration paths, to understand their behavioral responses. Our observations revealed that while some turtles undertook extensive migrations to high-use areas in the Northeast and Northwest Atlantic, the majority remained within the boundaries of the Gulf of Mexico. The study effectively differentiated migration and feeding behavior, noting a clear positive relationship between feeding activities and chlorophyll concentration, while productivity played only a marginal role, and no influence was found for SST and mesoscale eddies. This study advances knowledge of North Atlantic leatherback turtle migrations, underscoring the importance of integrated, multidisciplinary marine conservation efforts. Understanding the impact of climate warming on migration paths and food source availability necessitates a holistic approach encompassing changes in physical oceanography, nutrient dynamics, and interactions from plankton to higher trophic levels. Additionally, as leatherback turtles traverse various international territories, the research emphasizes the need for collaborative data collection for their effective protection.

Developmental Thermal Reaction Norms of Leatherback Marine Turtles at Nesting Beaches.

Accurate scientific information is critical for undertaking appropriate conservation and management practices for imperiled species. One source of concern is that research findings might vary for non-biological reasons, including experimental design and analytical methods. To illustrate, we provide detailed modern analysis of reproductive data for leatherback turtles (Dermochelys coriacea). This species exhibits significant fluctuations in nesting densities across different regions, possibly driven by local rather than global factors. Key factors influencing these changes include hatching success and sex determination, both sensitive to incubation temperatures (e.g., lower temperatures yield more males, higher temperatures yield females). This study updates the understanding of temperature-dependent sex determination (TSD) in this species using Bayesian statistics. Growth rate data from the West Pacific and Northwest Atlantic populations show a similar, monotone increase with temperature, affirming the reliability of the models used. The analysis of TSD patterns indicates that observed differences are more likely due to study methodologies and clutch-specific factors rather than regional differences. These findings challenge previous assumptions, showing that leatherback TSD does not conform to a simple on/off pattern but is influenced by multiple, interacting environmental factors. Population dynamics models must account for these complexities, recognizing that both sex ratios and hatching success are critical to understand the rapid changes observed in some leatherback populations.

Stock identification of sympatric Atlantic cod populations in the Gulf of Maine and mixed stock fishery analysis using otolith-based techniques

Sympatric populations of Atlantic cod with distinct spawning times in winter and spring have been identified within the Gulf of Maine. A new western Gulf of Maine stock assessment unit in U.S. waters lumps winter and spring spawning populations into a single stock unit and future monitoring and assessment of their abundance will require mixed stock analysis. The goal of this study was to evaluate the utility of otolith-based stock identification techniques to discriminate spawning populations. Significant differences in otolith structure and microchemistry were identified between winter and spring spawners with the highest degree of classification accuracy based on both features. Mixed stock analysis applied to fishery samples of unknown origin indicated the contemporary (2015-2016) commercial fishery is dominated by winter spawners. Exploratory classification of historical fishery samples suggested a change over time with spring and winter spawners present in near equal proportion in the early 1990s and winter spawners dominating in the early 1980s. Otolith-based stock composition analysis has the potential to support monitoring and assessment of cod populations in the Gulf of Maine.

Overwintering humpback whales adapt foraging strategies to shallow water environments at the mouth of the Chesapeake Bay, Virginia, USA

AbstractSome humpback whales from the Northwestern Atlantic population forgo migration to the Caribbean, spending winter months feeding along the U.S. mid‐Atlantic coast. We studied the foraging behavior of these whales at the mouth of the Chesapeake Bay, Virginia during winter from 2017 to 2022. While shipping channels here reach depths of up to 30 m, most of the area is 11–15 m deep. This shallow‐water environment poses physical constraints on classical humpback whale feeding modes. We deployed 20 digital acoustic tags (DTAGs) on humpback whales and identified foraging lunges from accelerometer data, detecting 788 lunges from 10 animals. Tagged whales averaged a single lunge per dive, lunging primarily in a horizontal orientation, with limited maneuvering compared to other study sites. Our results indicate that some elements of humpback whale foraging behavior are conserved across environments, but that the shallow depths in our study area constrain how animals are able to feed. The relatively high lunge rates we observed suggest this area is an important foraging ground. However, foraging in shipping channels increases the risk of ship strikes, which frequently occur in this area.

Is the typical stage of Penicillus capitatus Lamarck (Bryopsidales, Halimedaceae) a possible indicator of climate warming?

In this study, through morphological and molecular analysis approaches, we documented the presence of the typical stage (adult stage) of Penicillus capitatus during the coldest seasons of the year, typically periods when this form had never been reported in the Mediterranean. Indeed, the typical stage is common throughout the year in the western Atlantic (native range of the species), whereas it is rare in the Mediterranean, where the Espera stage (juvenile stage) is the main stage. To date, in the Mediterranean, the adult stage has been found only in the warmer months of the year. Therefore, the observation of the typical stage in the Mediterranean Sea during the cold season might suggest a general increase in the seawater temperature in this basin, rendering this stage of P. capitatus a potential climate bioindicator. Furthermore, owing to the molecular analysis methods adopted, it was possible to assess the relationships between the Mediterranean and Atlantic populations of this species.

Evidence for gene flow from the Gulf of Mexico to the Atlantic Ocean in bonnethead sharks (Sphyrna tiburo).

Gene flow is important for maintaining the genetic diversity required for adaptation to environmental disturbances, though gene flow may be limited by site fidelity in small coastal sharks. Bonnethead sharks (Sphyrna tiburo)-a small coastal hammerhead species-demonstrate site fidelity, as females are philopatric while males migrate to mediate gene flow. Consequently, bonnetheads demonstrate population divergence with distance, and Atlantic populations are genetically distinct from those of the Gulf of Mexico. Indeed, Florida forms a vicariant zone between these two bodies of water for many marine species, including some sharks. However, while bonnetheads are expected to have limited dispersal, the extent and rate of bonnethead migration remain uncertain. Thus, we aimed to determine their dispersal capacity by evaluating connectivity between disparate populations from the Gulf of Mexico and Atlantic Ocean. Using 10,733 SNPs derived from 2bRAD sequences, we evaluated genetic connectivity between Tampa Bay on the Gulf Coast of Florida and Biscayne Bay on the Atlantic coast of Florida. While standard analyses of genetic structure revealed slight but significant differentiation between Tampa Bay and Biscayne Bay populations, demographic history inference based on the site frequency spectrum favored a model without divergence. However, we also estimate that if population divergence occurred, it would have been recent (between 1500 and 4500 years ago), with continuous unidirectional gene flow from Tampa Bay to Biscayne Bay. Our findings support the hypothesis that bonnetheads can migrate over relatively large distances (>300 miles) to find mates. Together, these results provide optimism that under proper management, a small-bodied globally endangered shark can undergo long migrations to sustain genetic diversity.

Genetic Sex and Origin Identification Suggests Differential Migration of Male and Female Atlantic Bluefin Tuna (Thunnus thynnus) in the Northeast Atlantic

ABSTRACTKnowledge about sex‐specific difference in life‐history traits—like growth, mortality, or behavior—is of key importance for management and conservation as these parameters are essential for predictive modeling of population sustainability. We applied a newly developed molecular sex identification method, in combination with a SNP (single nucleotide polymorphism) panel for inferring the population of origin, for more than 300 large Atlantic bluefin tuna (ABFT) collected over several years from newly reclaimed feeding grounds in the Northeast Atlantic. The vast majority (95%) of individuals were genetically assigned to the eastern Atlantic population, which migrates between spawning grounds in the Mediterranean and feeding grounds in the Northeast Atlantic. We found a consistent pattern of a male bias among the eastern Atlantic individuals, with a 4‐year mean of 63% males (59%–65%). Males were most prominent within the smallest (< 230 cm) and largest (> 250 cm) length classes, while the sex ratio was close to 1:1 for intermediate sizes (230–250 cm). The results from this new, widely applicable, and noninvasive approach suggests differential occupancy or migration timing of ABFT males and females, which cannot be explained alone by sex‐specific differences in growth. Our findings are corroborated by previous traditional studies of sex ratios in dead ABFT from the Atlantic, the Mediterranean, and the Gulf of Mexico. In concert with observed differences in growth and mortality rates between the sexes, these findings should be recognized in order to sustainably manage the resource, maintain productivity, and conserve diversity within the species.

Adaptation in landlocked Atlantic salmon links genetics in wild and farmed salmon to smoltification

Increased knowledge of heritable traits in Atlantic Salmon (Salmo salar) is important to overcome bottlenecks in salmonid aquaculture. Atlantic salmonid populations, both landlocked and anadromous, represent an interesting model to gain insight into anadromy related traits, most notably, the probability to smoltify. While a previous study has identified several genomic regions diverging between anadromous and landlocked populations across the species range, the present study explores these data further with the aim to uncover if some of these genomic regions are linked to beneficial genetic traits associated with smoltification. In this study 17 of these loci were monitored in 669 anadromous salmon originating from 36 full-sibling families that had been reared under common garden conditions. The Smolt Index was calculated, using multiple visual markers, and provided a means of assessing smoltification stage. One SNP, located in Ssa04, showed a significant association with probability to smoltify, where individuals homozygous for the landlocked variant (LL) displayed a decrease in probability of smoltifying after one winter when compared with the homozygous for the anadromous variant (AA). This effect was independent of individual fish size. A separate common garden study comprising 200 individuals from either anadromous or landlocked strains showed that expression levels of ncor1, a thyroid mediator hormone located on the same chromosomal region (Ssa04), were significantly reduced in landlocked individuals post smoltification but remained constant in their anadromous counterparts. This study therefore suggests that while size is still the most important trigger for the induction of smoltification, there may also be an additional genetic component or trigger that has been ‘lost’ during the years deprived of SW transfer. In conclusion, the LL genotype identified here could potentially be used by the industry to delay smoltification and may also represent one of the first clues to the genetic regulation of smoltification in Atlantic salmon.

Genetic and environmental considerations for the utilization of Pinus pinaster Ait. provenances across a region lacking proper local genetic materials

Maritime pine (Pinus pinaster Ait.) covers vast areas and is of economic importance in southwestern Europe, particularly in Galicia (NW Spain). Galicia is a heterogeneous region with an Atlantic climate in the coast and a Mediterranean-like climate in the inland, where forest reproductive materials (FRM) with proper adaptation, productivity and timber quality are not available. Thus, there is a need for tailored FRM recommendations for reforestation in this region. P. pinaster is particularly sensitive to environmental variation and shows significant intraspecific genetic variability in this sensitivity, so understanding population responses to environmental variation becomes crucial for proper selection of FRM. Taking advantage of volume growth and stem straightness 13 years after planting, assessed on c. 7500 trees from 25 P. pinaster populations established in seven common gardens across inland Galicia, we analyzed intraspecific variation in sensitivity to climate, geographic, edaphic and site quality factors. We used Mantel correlations and factorial regression models to distinguish the environmental parameters explaining the observed population × site interaction. We also estimated population phenotypic plasticity across sites and the existing genetic relationship between growth and stem straightness to define the optimal selection strategy for productivity purposes. Results showed a quantitatively significant population × site interaction for growth whereas it was almost negligible for stem straightness. In the case of growth, no specific environmental factor was able to explain the population relative performance across test sites, being site quality the only significant factor but with low power to describe the patterns found. Population differences were maximized in higher site quality conditions, where the largest gains from planting selected populations would be expected. Tree growth and straightness were not genetically correlated. Based on these results, subdividing inland Galicia for deployment of P. pinaster FRM throughout specific selections for each subregion is not recommended. Selecting FRM based on average growth and its phenotypic stability should be also avoided, as both properties were negatively correlated. We recommend selecting FRM based on the results from high quality sites, where Atlantic origin populations with high levels of genetic improvement showed the fastest growth. The inclusion of selection criteria based on stem straightness did not alter recommendations given that fast growing FRM showed intermediate or slightly above-average straightness. The limited explanatory power of climate factors for the population × site interaction prevents adjusting recommendations in light of the projected climate change.

The influence of environment on invasive Carpobrotus sp. populations across genetic clusters

The study aims to explore the natural variation in the metabolome of different populations of the invasive plant Carpobrotus from different genetic clusters and geographical origins to enhance our comprehension of its involvement in the adaptation process and phenotypic diversity. The metabolomic profile of shoots was analysed in four populations from two different genetic clusters (Cluster A: Cádiz and A Lanzada; Cluster B: La Marina and Samil) and two different biogeographical regions in Spain (Atlantic: Samil and A Lanzada; Mediterranean: Cádiz and La Marina), collected in the field and subsequently grown in the greenhouse. In addition, climatic, and physiological parameters were analysed. The Mediterranean populations (Cádiz and La Marina) showed lower initial weight and length measurements in morphological parameters than the Atlantic populations. On the contrary, only root parameters showed significant differences in growth parameters among populations. The analysis of ion levels revealed a consistent pattern of higher concentrations in shoots compared to roots, with significant differences among populations, particularly in sodium (Na+) and chlorides (Cl−) levels. Regarding metabolomic analysis, clear correlations between the metabolome, genetic and climatic conditions of Carpobrotus sp.pl populations are described. Pairwise comparisons using t-tests and Principal Component Analysis (PCA) indicated that the differences in metabolomic profile between the Samil and La Marina populations, which correspond to the same genetic cluster (cluster B), were smaller than in the rest of the comparisons indicating that populations from the same genetic cluster were more similar metabolically than those from the same climatic region. The study identified key metabolites representative of each cluster, with significant differences in amino acids, organic acids, and sugars contributing to the variation among populations. Pathway analysis highlighted the impact of climatic conditions on metabolic pathways, particularly in populations from Cluster A. In conclusion, the different populations were more similar according to the genetic cluster than to the climatic region of origin when studied at the metabolomic level. Consequently, the metabolites more representative of each cluster were also identified.

Mitochondrial, nuclear and morphological differentiation in the swimming crab Liocarcinus depurator along the Atlantic-Mediterranean transition

Environmental gradients in the sea may coincide with phenotypic or genetic gradients resulting from an evolutionary balance between selection and dispersal. The population differentiation of the swimming crab, Liocarcinus depurator, an important by-catch species in the Mediterranean Sea and North-East Atlantic, was assessed using both genetic and morphometric approaches. A total of 472 specimens were collected along its distribution area, and 17 morphometric landmarks, one mitochondrial gene (COI) and 11 polymorphic microsatellite markers were scored in 350, 287 and 280 individuals, respectively. Morphometric data lacked significant differences, but genetic analyses showed significant genetic differentiation between Atlantic and Mediterranean populations, with a steeper gradient in COI compared to microsatellite markers. Interestingly, nuclear differentiation was due to an outlier locus with a gradient in the Atlantic-Mediterranean transition area overlapping with the mtDNA gradient. Such overlapping clines are likely to be maintained by natural selection. Our results suggest a scenario of past isolation with local adaptation and secondary contact between the two basins. Local adaptation during the process of vicariance may reinforce genetic differentiation at loci maintained by environmental selection even after secondary contact.

Examining fish scale biomineral from Atlantic salmon populations.

Fish scale microchemistry can be used to make life-history inferences, although ecological studies examining scale composition are relatively rare. Salmon scales have an external layer of calcium phosphate hydroxyl apatite (HAP). The structure, hardness, and calcium content of this layer have been shown to vary within and between species. This variation may lead to misinterpretation of trace element profiles. This study uses backscatter scanning electron microscopy with electron dispersive spectrometry to compare scales from salmon populations and to present a more detailed analysis of scale HAP than was previously available. Our findings extend the range of salmon populations for which HAP Ca is available and confirm previous findings that the HAP Ca is relatively invariable within this species.

Further evidence for diversification within the Diogenes pugilator complex (Anomura, Diogenidae) in the Mediterranean and Black Seas

Abstract We document an unrecognised genetic lineage within the European hermit crab Diogenes pugilator species complex. Specifically, we propose the revalidation of the previously synonymised species D. ponticus, for specimens previously identified as D. pugilator from the Adriatic, Ionian, Aegean, and Black Seas. Analyses of the mitochondrial genes COI and 16S rRNA resulted in a clear genetic separation to East Atlantic and Western Mediterranean populations of Diogenes. Morphological analyses confirmed differences in the individuals assigned to D. ponticus compared to the congeners D. curvimanus and D. pugilator and thereby a concordance between molecular and morphological characters. Despite the relatively high morphological resemblance to D. armatus, the molecular differentiation and the remarkable geographic segregation within the species complex suggest at least one speciation or radiation event in the past, underlining the growing importance of molecular methods in the identification of species and evolutionarily significant units. Major oceanographic processes that are known to shape genetic variability and population genetic structure in the marine environment are pointed out as possible structuring factors for the observed intrageneric divergence. The evidence of long evolutionary independence is therefore considered sufficient to re-establish the validity of D. ponticus as a valid species in the northern-central and north-eastern Mediterranean Sea and the Black Sea and is redescribed accordingly.

Panmixia and local endemism: a revision of the Eubranchus rupium species complex with a description of new species.

Species of the genus Eubranchus Forbes, 1838 (Mollusca: Gastropoda: Nudibranchia) are common faunistic elements of boreal benthic ecosystems, associated with hydroid communities. Recent studies have suggested that the widely distributed trans-Arctic E. rupium (Møller, 1842) constitutes a complex of at least three candidate species, but the detailed taxonomy of the complex remains unresolved. The purpose of the present paper is to conduct an integrative taxonomic study including molecular genetic methods (a phylogenetic analysis using COI , 16S rRNA and histone H3 with application of species delimitation methods) and morphological study (light and scanning electron microscopy) of E. rupium and closely related species. The specific aims of this study were to establish the species boundaries, morphological variability, and the phylogeographic structure within this group. The phylogeographic analysis included a TCS -based network analysis, an analysis of molecular variance (AMOVA), divergence time estimations, and ancestral area reconstructions. We demonstrate that specimens initially identified as E. rupium included three distinctive species: the nominal E. rupium with an amphiboreal range, the new species Eubranchus novik sp. nov. from the Sea of Japan, for which a taxonomic description is provided in this paper, and Eubranchus sp. from the northern Kuril Islands, which requires the collection and study of additional material for formal description. Our results confirm the amphiboreal distribution of E. rupium , as no geographic structure was found across Pacific, Arctic and Atlantic populations, and the results of the AMOVA analysis showed no differences between groups of samples from different geographic regions. The divergence of the 'Eubrancus rupium species complex' is estimated from the late Miocene or the Miocene-Pliocene boundary to the late Pliocene. It is hypothesised that the most probable ancestral region for the Eubranchus rupium species complex is the north-western Pacific, and the subsequent speciation likely occurred due to dispersal followed by allopatric speciation. ZooBank: urn:lsid:zoobank.org:pub:228E0C46-0BF7-4DDD-9C00-67B50E298D65.

The effect of surveillance fishing on migration distance of Atlantic Salmon during the spawning period

AbstractObjectiveSurveillance fishing surveys can be performed to estimate the proportion of farmed salmon represented in the spawning stock of native Atlantic Salmon Salmo salar populations. These surveys take place after the recreational fishing period and therefore closer to the spawning period than the open recreational fishing season. Although catch‐and‐release angling has been demonstrated to affect salmon migration during the summer months, surveillance fishing that is conducted close to the spawning time could have more severe effects.MethodsTo test this, the migration distance of Atlantic Salmon (n = 74) caught in the Orkla River, Norway, was tracked by use of radiotelemetry. One group was tagged during the regular fishing season in the summer (control group), whereas another group was tagged in autumn during surveillance fishing (surveillance group).ResultSixty‐one salmon remained for analysis after we excluded fish that were recaptured, died, or migrated to other rivers. Relocation of the salmon during autumn (October 11–31) was used to compare movements and test for differences in migration using negative binomial regression because distances were nonnegative integers. During the tracking period, the surveillance group moved 12 ± 14 km (mean ± standard deviation) and the control group moved 13 ± 15 km; both groups moved 1 ± 2 km/day on average. There was no evidence that surveillance fishing impacted movement of the salmon compared to controls. However, one salmon died after tagging and three were not released due to injuries; total mortality of 9% during surveillance fishing could be unsustainable for smaller populations. Consequently, factors such as surveillance sample size, the status of the salmon population, and the population size should be assessed for each river individually when deciding the necessity of and approach to surveillance fishing.ConclusionThe results support existing recommendations to use careful handling and to end surveillance at least 2 weeks prior to the expected onset of spawning, thus providing a sufficiently long period for recovery after surveillance fishing.

Food chain without giants: modelling the trophic impact of bowhead whaling on little auk populations in the Atlantic Arctic.

In the Atlantic Arctic, bowhead whales (Balaena mysticetus) were nearly exterminated by European whalers between the seventeenth and nineteenth centuries. The collapse of the East Greenland-Svalbard-Barents Sea population, from an estimated 50 000 to a few hundred individuals, drastically reduced predation on mesozooplankton. Here, we tested the hypothesis that this event strongly favoured the demography of the little auk (Alle alle), a zooplanktivorous feeder competitor of bowhead whales and the most abundant seabird in the Arctic. To estimate the effect of bowhead whaling on little auk abundance, we modelled the trophic niche overlap between the two species using deterministic simulations of mesozooplankton spatial distribution. We estimated that bowhead whaling could have led to a 70% increase in northeast Atlantic Arctic little auk populations, from 2.8 to 4.8 million breeding pairs. While corresponding to a major population increase, this is far less than predicted by previous studies. Our study illustrates how a trophic shift can result from the near extirpation of a marine megafauna species, and the methodological framework we developed opens up new opportunities for marine trophic modelling.

Ontogenetic variation in the marine foraging of Atlantic salmon functionally links genomic diversity with a major life history polymorphism.

The ecological role of heritable phenotypic variation in free-living populations remains largely unknown. Knowledge of the genetic basis of functional ecological processes can link genomic and phenotypic diversity, providing insight into polymorphism evolution and how populations respond to environmental changes. By quantifying the marine diet of Atlantic salmon, we assessed how foraging behaviour changes along the ontogeny, and in relation to genetic variation in two loci with major effects on age at maturity (six6 and vgll3). We used a two-component, zero-inflated negative binomial model to simultaneously quantify foraging frequency and foraging outcome, separately for fish and crustaceans diets. We found that older salmon forage for both prey types more actively (as evidenced by increased foraging frequency), but with a decreased efficiency (as evidenced by fewer prey in the diet), suggesting an age-dependent shift in foraging dynamics. The vgll3 locus was linked to age-dependent changes in foraging behaviour: Younger salmon with vgll3LL (the genotype associated with late maturation) tended to forage crustaceans more often than those with vgll3EE (the genotype associated with early maturation), whereas the pattern was reversed in older salmon. Vgll3 LL genotype was also linked to a marginal increase in fish acquisition, especially in younger salmon, while six6 was not a factor explaining the diet variation. Our results suggest a functional role for marine feeding behaviour linking genomic diversity at vgll3 with age at maturity among salmon, with potential age-dependent trade-offs maintaining the genetic variation. A shared genetic basis between dietary ecology and age at maturity likely subjects Atlantic salmon populations to evolution induced by bottom-up changes in marine productivity.

Sex-specific overdominance at the maturation vgll3 gene for reproductive fitness in wild Atlantic salmon.

Linking reproductive fitness with adaptive traits at the genomic level can shed light on the mechanisms that produce and maintain sex-specific selection. Here, we construct a multigenerational pedigree to investigate sex-specific selection on a maturation gene, vgll3, in a wild Atlantic salmon population. The vgll3 locus is responsible for ~40% of the variation in maturation (sea age at first reproduction). Genetic parentage analysis was conducted on 18,265 juveniles (parr) and 685 adults collected at the same spawning ground over eight consecutive years. A high proportion of females (26%) were iteroparous and reproduced two to four times in their lifetime. A smaller proportion of males (9%) spawned at least twice in their lifetime. Sex-specific patterns of reproductive fitness were related to vgll3 genotype. Females showed a pattern of overdominance where vgll3*EL genotypes had three-fold more total offspring than homozygous females. In contrast, males demonstrated that late-maturing vgll3*LL individuals had two-fold more offspring than either vgll3*EE or vgll3*EL males. Taken together, these data suggest that balancing selection in females contributes to the maintenance of variation at this locus via increased fitness of iteroparous vgll3*EL females. This study demonstrates the utility of multigenerational pedigrees for uncovering complex patterns of reproduction, sex-specific selection and the maintenance of genetic variation.

Multi‐year monitoring shows higher species richness and diversity of fish assemblages in a Danish seagrass meadow as compared to neighbouring non‐vegetated areas

AbstractSeagrass meadows provide an important nursery and feeding habitat for fish, globally. However, limited data exist on how these vegetated coastal ecosystems affect local fish stocks over longer time periods. By means of beach seine hauling with a bio‐monitoring seine net, we collected fish data in Kronborg Bay (Denmark) over 4 years. The bay contains both vegetated and bare sediment areas in close proximity to Kronborg Castle in Elsinore and is part of the Øresund strait; a dynamic marine environment linking the Baltic Sea with the inner Danish waters (Kattegat). We investigated the biodiversity and fish abundance in a healthy seagrass meadow and compared it with a bare adjacent sediment area. We show that seagrass is important for fish species like the Atlantic cod, the two‐spotted goby, and the broadnosed pipefish. The seagrass meadow harboured more fish species and higher biodiversity, while the number of individuals was higher in the adjacent bare sediment area as a result of high abundances of lesser sand eel. Pilou's evenness and the Shannon‐Wiener index showed 2–4‐fold higher biodiversity in the seagrass meadow. The seagrass meadow harboured about 35% more fish species than the bare adjacent sediment. The Atlantic cod was almost entirely found in the seagrass meadow, while lesser sand eel that showed an overall increase in abundance in both habitats, represented the largest proportion of the total number of fish individuals (up to about 60%) and was mostly found on the bare adjacent sediment. Species abundance was analysed for changes over time, where, for example the European plaice showed an increase in abundance over the 4‐year period of investigation. Seagrass meadows can thus be very important for the Atlantic cod population in the Øresund strait and generally for local fish productivity, abundance and diversity.

Amphiatlantic Dolphins’ Prey: Indicators of Speciation, Trophic Competition and Global Warming? A Review

A review of the prey of three amphiatlantic dolphin species, Tursiops truncatus, Stenella coeruleoalba and Delphinus delphis, is carried out. The main objective of this work is to review the feeding of these species in the Atlantic in order to assess the degrees of trophic competition and speciation pressure. A total of 103 fish families, 22 cephalopod families and 19 crustacean families have been counted, from which the species identified to the genus level only included seventy-one fish, twenty cephalopods and five crustaceans, and the total species identified included three-hundred-one fish, fifty cephalopods and twenty-six crustaceans. The most consumed prey were fish, followed by cephalopods and crustaceans. The exclusive prey consumed by each of the three dolphin species, as well as those shared by all or at least two of them, have also been counted. T. truncatus is the most general; however, the western Atlantic populations exhibit high dietary specialization compared to the eastern Atlantic populations, reflecting strong speciation pressure on both sides of the Atlantic. D. delphis and S. coeruleoalba, despite their amphiatlantism, have hardly been studied in the western Atlantic, except for a few references in the southern hemisphere, so the fundamental differences between the two species and their comparison with T. truncatus have been established with records from the eastern Atlantic. All three dolphin species have been observed to be expanding, especially D. delphis. This northward expansion and that of their prey is discussed.