Seafood Species Research Articles

Elemental fingerprints of bivalve shells (Ruditapes decussatus and R. philippinarum) as natural tags to confirm their geographic origin and expose fraudulent trade practices

Bivalves are some of the most valued and consumed seafood species worldwide. However, these organisms can represent a threat to consumers’ health, particularly species harvested from contaminated areas (e.g., historical pollution by heavy or toxins produced by phytoplankton). The elemental composition of bivalve shells generally mirrors the geochemical conditions of the habitat where these organisms have grown. As such, in this study, the geographic origin of two economically important bivalves, the grooved carpet shell ( Ruditapes decussatus ) and Manila clam ( R. philippinarum ), sourced from several locations along the NW, W and SW Iberian coast was confirmed based on the EF of their shells. Overall, random forest analyses of EF (expressed as ratios to Ca) correctly identified the site of harvest of individuals with remarkably high success rate among locations (96.3% for R. decussatus and 98.1% for R. philippinarum ). In general, the most relevant ratios for this discrimination success were the same for both species (i.e., Ba/Ca, Co/Ca, Fe/Ca and Mn/Ca). However, species-specific differences in the EF of shells could also be perceived for specimens of the two bivalve species sampled in the same location. The present findings can allow authorities to expose fraudulent practices associated with the mislabeling of geographic origin of bivalves, namely R. philippinarum , whose harvest in one of the sampled locations (Tagus estuary) is currently forbidden due to public health issues, and develop origin certification for highly valued bivalve species sourced from specific locations (such as R. decussatus from Ria Formosa). • Elemental fingerprints (EF) of bivalve shells ( Ruditapes spp.) differed spatially. • The EF of shells trace the geographic origin of R. decussatus and R. philippinarum . • The EF of shells presented species-specific variations within the same location. • Spatial variations of EF can allow origin certification and expose illegal fishing.

Signature of climate-induced changes in seafood species served in restaurants

Signature of climate-induced changes in seafood species served in restaurants

The value of monitoring in efficiently and adaptively managing biotoxin contamination in marine fisheries

Harmful algal blooms (HABs) can produce biotoxins that accumulate in seafood species targeted by commercial, recreational, and subsistence fisheries and pose an increasing risk to public health as well as fisher livelihoods, recreational opportunities, and food security. Designing biotoxin monitoring and management programs that protect public health with minimal impacts to the fishing communities that underpin coastal livelihoods and food systems is critically important, especially in regions with worsening HABs due to climate change. This study reviews the history of domoic acid monitoring and management in the highly lucrative U.S. West Coast Dungeness crab fishery and highlights three changes made to these programs that efficiently and adaptively manage mounting HAB risk: (1) expanded spatial-temporal frequency of monitoring; (2) delineation of clear management zones; and (3) authorization of evisceration orders as a strategy to mitigate economic impacts. Simulation models grounded in historical data were used to measure the value of monitoring information in facilitating efficient domoic acid management. Power analysis confirmed that surveys sampling 6 crabs (the current protocol) have high power to correctly diagnose contamination levels and recommend appropriate management actions. Across a range of contamination scenarios, increasing the spatial-temporal frequency of monitoring allowed management to respond more quickly to changing toxin levels and to protect public health with the least impact on fishing opportunities. These results highlight the powerful yet underutilized role of simulation testing and power analysis in designing efficient biotoxin monitoring programs, demonstrating the credibility of these programs to stakeholders, and justifying their expense to policymakers.

Microplastic contamination in seafood from Dongshan Bay in southeastern China and its health risk implication for human consumption

Microplastic (MP) pollution has been a considerable concern due to its ubiquity in the environment and its potential to harm human health. Unfortunately, the exact levels of MP in various species of seafood species have not been established. It is also unclear whether or not consuming seafood contaminated with MPs directly jeopardizes human health. Here, eight popular species of seafood in Dongshan Bay, China were investigated to determine the presence of MP pollution and its implications on human health. The abundance, color, size, shape, type, surface morphology, danger of the MPs extracted from the seafood were analyzed. Results showed that the average MP abundance in the shellfish and fish was 1.88 ± 1.44 and 1.98 ± 1.98 items individual−1, respectively. The heavy presence of fibers may be attributed to the shellfish and fish's feeding behaviors as well as their habitat and environment. The sizes of MPs found were below 1.0 mm. The main types of MP found in the shellfish were PES and PET, whereas the main types found in the fish were PS and PES. Risk assessment suggested that MPs in the shellfish (risk Level V) posed a greater and more direct threat to human health if the shellfish is eaten whole. The MPs in the gastrointestinal tracts (GITs) of fish (risk Level IV) have a relatively limited effect on human health since GITs are seldom consumed by humans unless the fish is heavily processed (canned or dried). MPs-induced health risk is predicted using a technique called molecular docking. The results of this study not only establish levels of MP pollution in popular seafood species but also help understand the implications of consuming MP-contaminated seafood on human health.

Plastics, prawns, and patterns: Microplastic loadings in Nephrops norvegicus and surrounding habitat in the North East Atlantic

The presence of microplastics (MPs), a contaminant of emerging concern, has attracted increasing attention in commercially important seafood species such as Nephrops norvegicus. This species lend themselves well as bioindicators of environmental contamination owing to their availability, spatial and depth distribution, interactions with seafloor sediment and position in the ecosystem and food chain. This study assesses the abundance of MPs in N. norvegicus and in benthic sediments across six functional units in the North East Atlantic. Assessment of the relationship between MP abundance in N. norvegicus, their biological parameters and their surrounding environment was examined. Despite the lack of statistical significance, MP abundances, size, shape, and polymer type recorded in N. norvegicus mirrored those found in the surrounding environment samples. The three main polymers identified in both organisms and sediment were polystyrene, polyamide (nylons), and polypropylene. The level of MP contamination in N. norvegicus could be related to local sources, with relatively low abundances recorded in this study for the North East Atlantic in comparison to other regional studies. Furthermore, larger organisms contained a lower abundance of MPs, demonstrating no accumulation of MPs in N. norvegicus. Based on the results of this study, data on MP ingestion could be used to study trends in the amount and composition of litter ingested by marine animals towards fulfilling requirements of descriptor 10 of the Marine Strategy Framework Directive.

Circulating trimethylamine N-oxide levels following fish or seafood consumption.

Some species of fish and seafood are high in trimethylamine N-oxide (TMAO), which accumulates in muscle where it protects against pressure and cold. Trimethylamine (TMA), the metabolic precursor to TMAO, is formed in fish during bacterial spoilage. Fish intake is promoted for its potential cardioprotective effects. However, numerous studies show TMAO has pro-atherothrombotic properties. Here, we determined the effects of fish or seafood consumption on circulating TMAO levels in participants with normal renal function. TMAO and omega-3 fatty acid content were quantified across multiple different fish or seafood species by mass spectrometry. Healthy volunteers (n = 50) were recruited for three studies. Participants in the first study consented to 5 consecutive weekly blood draws and provided dietary recall for the 24h preceding each draw. In the second study, TMAO levels were determined following defined low and high TMAO diets. Finally, participants consumed test meals containing shrimp, tuna, fish sticks, salmon or cod. TMAO levels were quantified by mass spectrometry in blood collected before and after dietary challenge. TMAO + TMA content varied widely across fish and seafood species. Consumption of fish sticks, cod, and to a lesser extent salmon led to significant increases in circulating TMAO levels. Within 1 day, circulating TMAO concentrations in all participants returned to baseline levels. We conclude that some fish and seafood contain high levels of TMAO, and may induce a transient elevation in TMAO levels in some individuals. Selection of low TMAO content fish is prudent for subjects with elevated TMAO,cardiovascular disease or impaired renal function.

Potentially toxic elements and microplastics in muscle tissues of different marine species from the Persian Gulf: Levels, associated risks, and trophic transfer

Selected potentially toxic elements (PTEs), including As, Cd, Co, Cr, Cu, Hg, Ni, Pb, Se, and Zn, along with microplastic particles (MPs) were characterized in the muscle of seafood species in order to study potential health risk and also investigate biomagnification of the contaminants. The results revealed high levels of the analyzed PTEs and MPs in crustaceans. The cancer risk among the consumer population (adult and children) posed by As is higher than the acceptable lifetime risk of 10−4. Portunus plagicus and Platycephalus indicus had the highest and lowest amount of MP particles in their muscles, respectively, among investigated species. Finally, PTEs (except Hg) and MPs are not biomagnified in the collected species. The results of this research emphasize the importance of accounting for health risks posed by potential pollutants via consumption of contaminated seafood.

Determination of phthalic acid esters and di(2-ethylhexyl) adipate in fish and squid using the ammonium formate version of the QuEChERS method combined with gas chromatography mass spectrometry

In the present study, the ammonium formate version of the QuEChERS method, considered highly advantageous in relation to instrument maintenance and other issues, was applied for the first time to extract a group of twelve phthalic acid esters (PAEs, i.e. dipropyl phthalate, DPP; diisobutyl phthalate, DIBP; dibutyl phthalate, DBP; diisopentyl phthalate, DIPP; di-n-pentyl phthalate, DNPP; dihexyl phthalate, DHP; butyl benzyl phthalate, BBP; dicyclohexyl phthalate, DCHP; di(2-ethylhexyl) phthalate, DEHP; di-n-octyl phthalate, DNOP; diisononyl phthalate, DINP; and diisodecyl phthalate, DIDP) and one adipate (di(2-ethylhexyl) adipate, DEHA) from two species of fish (Scomber colias and Katsuwonus pelamis) and one of squid (Loligo gahi). The method was validated in terms of linearity, trueness and matrix effects. Determination coefficients (R2) for matrix-matched calibration curves were higher than 0.99 in all cases, being the lowest calibration levels in the range 0.5–10 ng/g. Mean recovery values were between 70 and 117% with relative standard deviation values ≤20%. Matrix effects were soft (between −20 and +20%) for most analytes and matrices, except in squid samples, which was mostly medium with a moderate ion suppression. The analysis of 10 samples of each type showed the presence of DIBP, DBP and DEHP at concentrations up to 44.2 ± 2.1 ng/g of wet weight in some of the samples and species, still not representing concerning values when considering the daily intake of such species of seafood in the human diet (tolerable daily intake -TDI- values were not exceeded). Results demonstrated that the ammonium formate version of the QuEChERS method can be applied with success for the extraction and determination of the selected PAEs and DEHA in fish and squid samples.

Large volume headspace GC/MS analysis for the identification of volatile compounds relating to seafood decomposition.

Decomposition in seafood products in the United States is monitored by the Food and Drug Administration (FDA) laboratories using sensory testing, which requires highly trained analysts. A large‐volume headspace (LVHS) gas chromatography/mass spectrometry (GC/MS) method was developed to generate analytical results that can be directly compared to sensory evaluation. Headspace vapor was withdrawn from a 1‐L vial containing 50 g seafood sample using a large volume headspace autosampler. Various volatile compounds were collected simultaneously. Analytes were preconcentrated by a capillary column trapping system and then sent through a cryo‐focuser mounted onto the GC injector. A selected ion monitoring (SIM) MS acquisition method was used to selectively monitor 38 compounds of interest. Samples of red snapper, croaker, weakfish, mahi‐mahi, black tiger shrimp, yellowfin tuna, and sockeye salmon that have been assessed and scored by an FDA National Seafood Sensory Expert (NSSE) were used for method performance evaluation. Characteristic compounds potentially associated with seafood quality deterioration for each seafood species were identified by quantitative analysis using pooled matrix‐matched calibrations and two‐sample t‐test statistical analysis. Classification of fresh and decomposed samples was visualized on the analysis of variance (ANOVA)–principal component analysis (PCA) score plots. The results determined that the LVHS‐GC/MS technique appeared promising as a screening tool to identify compounds representative of sensory analysis.

Dietary exposure of zinc oxide nanoparticles (ZnO-NPs) from canned seafood by single particle ICP-MS: Balancing of risks and benefits for human health

The present study aims to give information regarding the quantification of ZnO-NPs in canned seafood, which may be intentionally or unintentionally added, and to provide a first esteem of dietary exposure. Samples were subjected to an alkaline digestion and assessment of ZnO-NPs was performed by the single particle ICP-MS technique. ZnO-NPs were found with concentrations range from 0.003 to 0.010 mg/kg and a size mean range from 61.3 and 78.6 nm. It was not observed a clear bioaccumulation trend according to trophic level and size of seafood species, although the mollusk species has slightly higher concentrations and larger size. The number of ZnO-NPs/g does not differ significantly among food samples, observing an average range of 5.51 × 106 - 9.97 × 106. Dissolved Zn determined with spICP-MS revealed comparable concentration to total Zn determined with ICP-MS in standard mode, confirming the efficiency of alkaline digestion on the extraction of the Zn. The same accumulation trend found for ZnO-NPs was observed more clearly for dissolved Zn. The ZnO-NPs intake derived from a meal does not differ significantly among seafood products and it ranges from 0.010 to 0.031 µg/kg b.w. in adult, and from 0.022 to 0.067 µg/kg b.w. in child. Conversely, the intake of dissolved Zn is significantly higher if it is assumed a meal of mollusks versus the fish products, with values of 109.3 µg/kg b.w. for adult and 240.1 µg/kg b.w. for child. Our findings revealed that ZnO-NPs have the potential to bioaccumulate in marine organisms, and seafood could be an important uptake route of ZnO-NPs. These results could be a first important step to understand the ZnO-NPs human dietary exposure, but the characterization and quantification of ZnO-NPs is necessary for a large number of food items

Interactions of Environmental Chemicals and Natural Products With ABC and SLC Transporters in the Digestive System of Aquatic Organisms.

An organism’s diet is a major route of exposure to both beneficial nutrients and toxic environmental chemicals and natural products. The uptake of dietary xenobiotics in the intestine is prevented by transporters of the Solute Carrier (SLC) and ATP Binding Cassette (ABC) family. Several environmental chemicals and natural toxins have been identified to induce expression of these defense transporters in fish and aquatic invertebrates, indicating that they are substrates and can be eliminated. However, certain environmental chemicals, termed Transporter-Interfering Chemicals or TICs, have recently been shown to bind to and inhibit fish and mammalian P-glycoprotein (ABCB1), thereby sensitizing cells to toxic chemical accumulation. If and to what extent other xenobiotic defense or nutrient uptake transporters can also be inhibited by dietary TICs is still unknown. To date, most chemical-transporter interaction studies in aquatic organisms have focused on ABC-type transporters, while molecular interactions of xenobiotics with SLC-type transporters are poorly understood. In this perspective, we summarize current advances in the identification, localization, and functional analysis of protective MXR transporters and nutrient uptake systems in the digestive system of fish and aquatic invertebrates. We collate the existing literature data on chemically induced transporter gene expression and summarize the molecular interactions of xenobiotics with these transport systems. Our review emphasizes the need for standardized assays in a broader panel of commercially important fish and seafood species to better evaluate the effects of TIC and other xenobiotic interactions with physiological substrates and MXR transporters across the aquatic ecosystem and predict possible transfer to humans through consumption.

Migration of bisphenol A and its related compounds in canned seafood and dietary exposure estimation

Abstract The present study sought to investigate the migration of target bisphenols, such as bisphenol-A (BPA), bisphenol-F (BPA), bisphenol-A diglycidyl ether (BADGE), bisphenol-A (2,3-dihydroxypropyl) glycidyl ether (BADGE·H2O), bisphenol-A bis(2,3-dihydroxypropyl) ether (BADGE·2H2O), and bisphenol F diglycidyl ether (BFDGE) in 102 samples of several canned seafood, namely canned Antarctic krill, scallop, oysters, mussel, clam, and mantis shrimp stored for months at different temperatures through a high-performance liquid chromatographic-fluorescence detector combined with a microwave-assisted extraction method. Except for BFDGE, the other five bisphenols were observed in most of the analyzed samples. The canned shrimp showed the highest migration of BPA (0.089 mg/kg), exceeding the specific migration limit (SML) of BPA (0.05 mg/kg) specified by the European Union, while the migration levels of BADGE and its derivatives were within their SMLs. The migration behavior of bisphenols in the canned seafood was majorly affected by the analytes, storage conditions, and food types. BPA, BADGE·H2O, and BADGE·2H2O were characterized by a rapid migration during the first half of the shelf life, which increased with the increase of temperature, followed by a stabilization or decline of their concentrations for prolonged durations. Besides, the migration of target bisphenols was significantly influenced by the storage temperature in some seafood species. Notably, higher migration level of BPA was found in samples with higher fat content. The average dietary exposure of Chinese adults to BPA, BPF, BADGE·2H2O, BADGE·H2O, and BADGE of canned seafood was estimated at 11.69, 1.21, 6.47, 8.74, and 4.71 ng/(kg·d), respectively. The target hazard quotient values of all the analyzed bisphenols were below 1 for the Chinese adults, suggesting an insignificant exposure to these bisphenols through canned seafood consumption.

Fish Flow: following fisheries from spawning to supper

Novel methodologies now make it possible to track the complete geographical movements of seafood species from reproduction to human consumption. Doing so will better inform consumers and assist resource managers in matching fisheries and conservation policies with natural borders and pathways, including stock boundaries, networks of marine protected areas, and fisheries management areas. Such mapping necessitates an unprecedented synthesis of natural and social sciences, including knowledge of adult fish population abundance and movements, egg output, larval dispersal, and recruitment to juvenile and adult habitats, as well as fisheries stock assessment, capture, and distribution through human social networks. The challenge is to fully integrate oceanography, population genetics, ecology, and social sciences with fisheries biology to reveal the patterns and mechanisms of “Fish Flow” from spawning to supper. As practitioners representing all five of these disciplines, we believe that Fish Flow analyses will promote sustainable fisheries management and marine conservation efforts, and may foster public knowledge, wise seafood choices, and appreciation of social–ecological interconnections involving fisheries.

Universal primer design for crustacean and bivalve-mollusc authenticity based on cytochrome-b gene

Abstract. Dwiyitno D, Hoffman S, Parmentier K, Keer CV. 2021. Universal primer design for crustacean and bivalve-mollusc authenticity based on cytochrome-b gene. Biodiversitas 23: 17-24. Fish and seafood authenticity is important to support traceability practices and protect the public from economic fraud and adulteration. Molecular-based techniques of PCR are known as the most common methods for identifying seafood species. Nevertheless, these techniques rely on the appropriate primer set designed to amplify specific DNA fragments on targeted species. For efficiency application on a wide range of species, a universal primer set is more valuable than a specific primer. The present study developed universal primers, especially for identifying crustaceans and molluscs based on the cytochrome b mitochondrial DNA (Cyt b). The initial primer pair of CytBL1/CytBH originally designed for fish species was applicable to amplify the Cyt b gene on most selected fish samples, but not for crustacean and mollusc samples. Based on annealing profile, sequence evaluation (92-100% similarity), and RT-PCR analysis, the universal primer couple of CytBL1C/CytBHW designed in the present study potentially applied to identify crustacean and mollusc samples, especially shrimp and bivalve-mollusc.

Quantitative risk-benefit assessment of Portuguese fish and other seafood species consumption scenarios.

Portugal has high fish/seafood consumption, which may have both risks and benefits. This study aims to quantify the net health impact of hypothetical scenarios of fish/seafood consumption in the Portuguese population using a risk-benefit assessment methodology. Consumption data from the National Food, Nutrition and Physical Activity Survey 2015-2016 (n 5811) were used to estimate the mean exposure to methylmercury and EPA + DHA in the current and the alternative scenarios considered. Alternative scenarios (alt) were modelled using probabilistic approaches to reflect substitutions from the current consumption in the type of fish/seafood (alt1: excluding predatory fishes; alt2: including only methylmercury low-level fishes) or in the frequency of weekly fish/seafood consumption (alt3 to alt6: 1, 3, 5 or 7 times a week, replacing fish/seafood meals with meat or others). The overall health impact of these scenarios was quantified using disability-adjusted life years (DALY). In the Portuguese population, about 11450 DALY could be prevented each year if the fish/seafood consumption increased to a daily basis. However, such a scenario would result in 1398 extra DALY considering the consumption by pregnant women and the respective risk on fetal neurodevelopment. Our findings support a recommendation to increase fish/seafood consumption up to 7 times/week. However, for pregnant women and children, special considerations must be proposed to avoid potential risks on fetal neurodevelopment due to methylmercury exposure.

SYBR-Green real-time PCR assay with melting curve analysis for the rapid identification of Mytilus species in food samples

Mytilus spp. mussels are one of the most commonly cultivated species in the European Union, being M. galloprovincialis, M. edulis and M. chilensis the main species marketed here. Therefore, the identification of this seafood species is critical for labelling, traceability and food safety purposes. In the present study, 174 samples have been employed for the development of an alternative fast, simple, reliable and cost-effective methodology for the identification of Mytilus spp. mussels commercialized in Europe. This real-time PCR assay with a SYBR Green post-PCR melting curve analysis targeting the polyphenolic adhesive protein gene developed was successfully applied to fresh, frozen and canned mussels, showing 100% of specificity, sensitivity and precision. Besides, results have demonstrated the applicability of the assay in different platforms without special software requirements. Therefore, the methodology described in this study is useful for the authentication of mussel samples and could be easily applied as a fast routine food control laboratory test.

Review of the toxic trace elements arsenic, cadmium, lead and mercury in seafood species from Algeria and contiguous waters in the Southwestern Mediterranean Sea.

An assessment is made of published data on concentrations of four toxic trace elements arsenic (As), cadmium (Cd), lead (Pb), mercury (Hg), and methyl mercury (MeHg) in seafood species from Algerian coastal waters. The data relate mainly to fish and mollusks, with Pb and Cd being the most studied elements. In contrast, no studies were found for As and MeHg in mollusks and crustaceans, and none for total Hg in crustaceans. Data analysis has shown that the element concentrations depend on the element analyzed, in particular its chemical form, and they vary with the species studied and the area where the organisms were sampled. As concentrations in muscle of sardine (Sardina pilchardus) from the eastern zone (Bejaia) (2.98mgkg-1 wet weight), Pb in muscle of tuna (Euthynnus alletteratus) (0.49mgkg-1 wet weight) from the western region (Mostaganem) and in muscle tissue of the mussel (Mytilus galloprovincialis) (10.67mgkg-1 dry weight) from Oran all exceed the threshold risk limits set by national and international regulations. Given these findings, to guarantee seafood safety for the Algerian consumer, it is recommended to carry out monitoring of these trace elements in seafood species caught along the Algerian coast, particularly the most consumed fish, i.e., sardines, and predators such as swordfish and tuna which can accumulate high concentrations of toxic metals, particularly Hg. Obtaining a regional assessment based on similar analyses from Tunisia and Morocco was severely hampered since few similar species or taxonomic groups were analyzed in all three countries.

Perceptions of plastic pollution in a prominent fishery: Building strategies to inform management

Plastic ingestion in seafood species, and human consumers, are thought to have potential harmful impacts. However, there is limited information from seafood industry stakeholder groups, including processors, traders and fishers, about how they perceive plastic pollution, its impacts and potential management. Using the South Australian Marine Scalefish Fishery as a case study, we uncover levels of awareness, knowledge and concern, as well as impacts and potential solutions of marine plastic pollution from commercial and recreational fishers and fishmongers. Stakeholders highlight key areas of concern and motivations to champion the mitigation of plastic pollution, and promote management pathways with increased stakeholder support, including the implementation of education resources, improvement of waste disposal facilities and exploration of plastic-free fishing equipment. Understanding the perceptions of stakeholder groups will inform policy makers and empower managers to build awareness strategies, shift opinions through communication and reduce plastic pollution.

Microplastic Abundance in Blood Cockles and Shrimps from Fishery Market, Songkhla Province, Southern Thailand

Microplastics have been one of the major pollutants in the marine environment throughout the recent decade. At present, microplastic contamination in marine ecosystems of Thailand region has become an increasing environmental concern because the ingestion of microplastics in marine organisms may adversely influence the safety of seafood. Cockles and shrimps widely distribute among marine organisms in Thailand since they are one of the commercial sources of seafood, which may be a route of exposure to microplastics towards human. This study documents a market survey in order to understand the extension of microplastic presence in blood cockles (Anadara granosa), fine shrimp (Metapenaeus elegans) and Indian white shrimp (Fenneropenaeus indicus) sold in the fishery market in Singhanakorn district, Songkhla province. These selected species are widely consumed and economically important, especially in the southern Thailand region. The total microplastic concentration in blood cockles is 4.71±0.06 n/g (wet weight) and 2.64±0.01 n/individual; in fine shrimp is 0.50±0.19 n/g (wet weight) and 3.70±1.12 n/individual; in Indian white shrimp is 0.69±0.48 n/g (wet weight) and 3.45±0.04n/individual. Discovered microplastics in all the species samples were mainly composed of microplastic fibres and black colour was found to be more predominant. Our results indicate that microplastic contamination is present in Thailand’s commercial seafood species. As microplastic able to be transferred to human through food web, we suggest further market-based survey studies on other seafood sources.

Factors Influencing Colonization and Survival of Juvenile Blue Crabs Callinectes sapidus in Southeastern U.S. Tidal Creeks

Tidal creeks along the southeastern U.S. and Gulf of Mexico coastlines provide nursery habitats for commercially and ecologically important nekton, including juvenile blue crabs Callinectes sapidus, a valuable and heavily landed seafood species. Instream and watershed urbanization may influence the habitat value that tidal creeks provide to blue crabs. We investigated natural and anthropogenic factors influencing juvenile blue crab occupancy dynamics in eight first-order tidal creeks in coastal North Carolina (USA). An auto-logistic hierarchical multi-season (dynamic) occupancy model with separate ecological and observation sub-models was fitted to juvenile blue crab presence/absence data collected over replicate sampling visits in multiple seasons at three fixed trapping sites in each creek. Colonization and survival are the processes operating on occupancy that are estimated with this formulation of the model. Covariates considered in the ecological sub-model included watershed imperviousness, the percent of salt marsh in each creek’s high tide area, percent salt marsh edge, site-level water depth, and site-level salinity. Temperature, salinity, and dissolved oxygen were covariates considered in the observation sub-model. In the ecological sub-model, watershed imperviousness was a meaningful negative covariate and site-level salinity was a positive covariate of survival probability. Imperviousness and salinity were each marginally meaningful on colonization probability. Water temperature was a positive covariate of detection probability in the observation sub-model. Mean estimated detection probability across all sites and seasons of the study was 0.186. The results suggest that development in tidal creek watersheds will impact occupancy dynamics of juvenile blue crabs. This places an emphasis on minimizing losses of natural land cover classes in tidal creek watersheds to reduce the negative impacts to populations of this important species. Future research should explore the relationship between imperviousness and salinity fluctuations in tidal creeks to better understand how changing land cover influences water chemistry and ultimately the demographics of juvenile blue crabs.