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Environments contain various forms of noise that can interfere with the ability of animal sensory systems to perceive information. One ubiquitous type of visual noise in shallow aquatic habitats is caustic flicker (or caustics), consisting of dynamically moving light patterns caused by the refraction of light when passing through the water's rippling surface. While some teleost fish avoid environments with caustic noise (where their prey can be more difficult to detect), it remains untested whether caustics affect the habitat selection of invertebrates. In the present study, we ask whether three invertebrate species, the shore crab Carcinus maenas, the brown shrimp Crangon crangon, and the common cuttlefish Sepia officinalis, prefer or avoid associating with environments with caustic noise, and whether caustics affect their behavioural activity and habitat exploration. To do this, we exposed the three species in binary choice experiments to different simulated caustic noise levels varying in their temporal (speed) and spatial (definition) components. Neither of the three tested invertebrate species spent more or less time in environments with higher caustic noise levels. While we also found no evidence that caustics affected the behavioural activity and exploration of Ca. maenas and S. officinalis, the brown shrimp Cr. crangon reduced its activity with increasing spatial caustic noise. However, all obtained effect sizes in this study were small, suggesting that caustic noise only minimally affects invertebrate behaviour. Overall, our results show that, unlike in teleost fish, caustics have limited influence on the habitat selection, exploration, and activity of crustaceans and cephalopods. [ABSTRACT FROM AUTHOR]

Knowing what birds eat is fundamental to understand the ecology and distribution of individuals and populations. Often, diet is assessed based on field observations and excrement analyses, which has previously been the case for Sanderling Calidris alba. This may have biased their known diets towards large prey with indigestible body parts that can still be recognized in faeces or regurgitations. A literature review of Sanderling diet worldwide showed that Sanderlings exploit a large diversity of prey. We carried out DNA metabarcoding on Sanderling faeces to get a complete view of their diet in the Wadden Sea during staging and moult from late July to early October. Given the diversity of available prey in the Wadden Sea, it was remarkable that 94% of the samples contained Brown Shrimp Crangon crangon which, next to the Shore Crab Carcinus maenas, were also the most abundant species in the samples. This study shows that whereas Sanderling can feed on a large variety of invertebrates, in the Wadden Sea during southward staging they primarily rely on Brown Shrimp [ABSTRACT FROM AUTHOR]

Upon settlement after a pelagic larval phase, brown shrimp Crangon crangon depend on intertidal flats. During low as well as high tide the young brown shrimp play roles as predators of meiofauna and as prey for fish and birds. Unlike the biology of the commercially important adults, knowledge on these juveniles remains sketchy. Here we provide an analysis of 35 years (1984–2018) of brown shrimp monitoring in May–June on intertidal flats in the westernmost Dutch Wadden Sea. Intertidal shrimp densities were sampled bi-weekly at three stations during low tide, using sampling corers. We show that over this 35-year period the appearance of shrimp on mudflats advanced by 12 days (− 0.34 days yr−1). Simultaneously, densities on 7 May increased by more than 2.4 times, from 28 shrimp m−2 in 1984 to 69 shrimp m−2 in 2018. Across years, mean shrimp length decreased from 12.6 to 10.7 mm, but length in early May did not change. The advancement in settlement and the increasing shrimp densities correlated with increases in the seawater temperatures in April more than during earlier times of the year. We propose four interpretations of these changes: (1) shrimp settle on the mudflat when they reach a certain 'threshold' length, (2) settlement of shrimp is controlled by a critical period of 'threshold' temperature sensitivity, (3) timing of shrimp settlement is a response to food availability on mudflats or (4) a direct response to inferred predation pressure. The different interpretations will lead to different scenarios of change in a warming world. [ABSTRACT FROM AUTHOR]

In this study, a microcosm experiment was conducted for 30 days to assess the impact of the presence of juvenile gray shrimp Crangon crangon on meiofauna. The results suggested that juvenile shrimp had a significant negative impact on the abundance of nematodes and copepods, but no effect on polychaetes. Moreover, nematodes showed a significant decline in individual weight. The collected nematodes were taxonomically identified and assigned to five functional traits: shapes of the tail and amphid, life history, feeding types, and adult length. The nematode traits were affected by the number of shrimp introduced, and descriptors followed normal or inversed bell-shaped curves. When no shrimp were present, the nematofauna had a higher species richness compared with treatments of 4, 8, and 12 shrimp. Bell-shaped curve patterns were common in relation to the two phases of feeding for C. crangon. During the first phase, C. crangon consumed the nematode species Oncholaimus campylocercoides; thereafter, shrimp fed mostly on the nematode Anticoma eberthi and copepods. [ABSTRACT FROM AUTHOR]

Meiobenthic nematodes are well-known bioindicators in aquatic ecosystem health programs. However, the explored taxa are still limited and practically devoted to the community level. The present study provided a new method of experimental isolation of a species from a pristine nematofauna. In our method, the nematofauna faced two types of sediment, namely, the leaves of Posidonia oceanica and shells of Mytilus galloprovincialis, under controlled laboratory conditions, and several changes in species composition occurred through gradual selection of the most adaptable nematode taxa to the new environments, which were previously defaunated. We used the selected nematode taxon, Marylynnia puncticaudata (Cyatholaimidae), to examine the possible effects of organic enrichment, and the results clearly showed that the body size of the nematodes significantly increased and they became fat when after enrichment using a powder made of marine agar (1200 mg l−1) and cuticles of Crangon crangon (900 mg l−1), but their relative body growth showed no discernible changes. [ABSTRACT FROM AUTHOR]

Growth rates are of fundamental interest for studying population dynamics of species when no age information is available. In these cases in situ growth proxies must be identified and validated, and here we tested whether RNA-DNA ratio (RD) and dry weight condition (DWC) can act as such proxies for the shrimp Crangon crangon. Growth rates (mm d–1) were determined for male and female shrimps (20 to 67 mm) reared at five different temperatures (5°C to 25°C) and caught in two different months (May, July). Due to the potential interactive effects of the factors sex, size, temperature and time, different statistical analysis were applied to test for linear interactions (factorial analysis of mixed data, FAMDs), nonlinear additive effects (generalized additive models, GAMs) and nonlinear interactions (nonlinear regression combined with GAMs). The FAMD indicated positive correlations between length, month and growth rate. A positive correlation between DWC and sex and between RD and temperature was also indicated. RD was not significant in the GAM but a nonlinear link between length, temperature and growth was found. Finally, an extended Bertalanffy growth model was fitted to sex-specific growth rates and in a second step a GAM was fitted to the differences (residuals) between observed and predicted growth. RD again had no significant explanatory power for growth and, although it is a commonly used growth proxy, we concluded that it is not a suitable index for evaluating length growth of C. crangon.

Two forms of NADP-dependent malic enzyme (ME, EC 1.1.1.40) were purified from the abdomen muscle of the crayfish Orconectes limosus (Rafinesque, 1817) and the shrimp Crangon crangon L., 1758 by affinity chromatography on 2′,5′-ADP-Sepharose 4B, with good qualitative recovery in a single step, using a substrate activation method with a malate–manganese chloride pair. The enzymes were identified by native polyacrylamide gel electrophoresis stained for protein and enzyme activity. The faster migrating mitochondrial enzyme from crayfish is inhibited by sulfhydryl reagent and loses its activity. Ellman's Reagent, 5,5′-Dithiobis-(2-nitrobenzoic acid) (DTNB), can be used for the differentiation and measurement of cytoplasmic and mitochondrial malic enzyme in decapod crustacean tissue. Résumé: Deux formes d'enzyme malique NADP dépendantes (ME, EC 1.1.1.40) ont été purifiées à partir du muscle abdominal de l'écrevisse Orconectes limosus (Rafinesque, 1817) et de la crevette Crangon crangon L., 1758 par chromatographie par affinité sur 2′,5′-ADP-Sepharose 4B, avec un bon retour qualitatif en une seule étape, en utilisant une méthode d'activation du substrat avec une paire malate-chlorure de manganèse. Les enzymes ont été identifiées par électrophorèse sur gel de polyacrylamide pour les protéines et l'activité enzymatique. L'enzyme mitochondriale de l'écrevisse qui migre le plus rapidement est inhibée par le réactif sulfhydryle et perd son activité. Le réactif d'Ellman (DTNB) peut être utilisé pour la différenciation et la mesure de l'enzyme malique mitochondriale cytoplasmique dans le tissu des décapodes. [ABSTRACT FROM AUTHOR]

In this study, logbook, landings, and vessel monitoring system data of German brown shrimp (Crangon crangon L.) fishers were combined to analyse spatial and temporal distribution patterns. Landings per unit effort (LPUE) were standardized to the efficiency level of a reference vessel. The standardization altered the spatial–temporal patterns of the LPUE as the vessels differed by a factor of up to 4.7. LPUE data were separated into two size classes according to sieve fractions. Small brown shrimps were characterized by LPUE values increasing early in the year in shallow waters, especially in estuaries in July. Subsequently, peak LPUE values are reached at the end of September in all depths, but with variable spatial patterns between years. LPUE data indicate a general outward migration between early summer and winter. In winter, large shrimp shows a clear increase in LPUE with depths mainly in regions adjacent to the Dutch coast and a reversed pattern close to the Danish coast. The large size class in winter—which consists mainly of mature or egg-bearing females—showed high LPUE values along two persistent diagonal bands in the German Bight. These patterns could lead to local recruitment overfishing, if fishermen are aware of such patterns. [ABSTRACT FROM AUTHOR]

Multiple enveloped viruses with rod-shaped nucleocapsids have been described, infecting the epithelial cell nuclei within the hepatopancreas tubules of crustaceans. These bacilliform viruses share the ultrastructural characteristics of nudiviruses, a specific clade of viruses infecting arthropods. Using histology, electron microscopy and high throughput sequencing, we characterise two further bacilliform viruses from aquatic hosts, the brown shrimp (Crangon crangon) and the European shore crab (Carcinus maenas). We assembled the full double stranded, circular DNA genome sequences of these viruses (~113 and 132 kbp, respectively). Comparative genomics and phylogenetic analyses confirm that both belong within the family Nudiviridae but in separate clades representing nudiviruses found in freshwater and marine environments. We show that the three thymidine kinase (tk) genes present in all sequenced nudivirus genomes, thus far, were absent in the Crangon crangon nudivirus, suggesting there are twenty-eight core genes shared by all nudiviruses. Furthermore, the phylogenetic data no longer support the subdivision of the family Nudiviridae into four genera (Alphanudivirus to Deltanudivirus), as recently adopted by the International Committee on Taxonomy of Viruses (ICTV), but rather shows two main branches of the family that are further subdivided. Our data support a recent proposal to create two subfamilies within the family Nudiviridae, each subdivided into several genera.

The restrictions and the concerted action of the global ban on the use and presence of tributyltin (TBT) in marine applications to protect ecosystems in the marine environment in 2008 was mainly based on the economic impact on shellfish industries and the dramatic extinction of local mollusk populations in the past. In contrast to the vast datasets on effects on mollusks, the knowledge on impacts on species from other taxa remained in the uncertain until almost two decades ago. The assumption on a long-term TBT-mediated pernicious metabolic bottom–up regulation of the crustacean Crangon crangon population was provoked by the outcome of an EU-project ‘Sources, Consumer Exposure and Risks of Organotin Contamination in Seafood.’ This study reported high TBT body burdens in C. crangon in 2003, at the start of the transition period to the global ban. Experimental research on the TBT impact in C. crangon focused on agonistic interference with natural ecdysteroid hormones at the metabolic pathways regulating growth and reproduction and the biogeochemical distribution of the chemical. In this paper, metabolic, topical and population-relevant biological endpoints in C. crangon and other crustaceans are evaluated in relation to the temporal and spatial trends on TBT’s occurrence and distribution in the field during and after the introduction of the tributyltin restrictions and endocrine-related incidents. Arguments are forwarded to relate the German Bight incident on growth and reproduction failure in the C. crangon population, despite the lack of direct evidence, to the pernicious impact of tributyltin in 1990/91 and previous years. The extreme occurrence of TBT in C. crangon from other parts of the southern North Sea and evidence on the high body burdens as dose metrics of exposure also feeds the suspicion on detrimental impacts in those areas. This paper further demonstrates the complexity of distinguishing and assessing the individual roles of unrelated stressors on a population in an integrated evaluation at the ecosystem level.

The European brown shrimp, Crangon crangon, is a highly valued commercial species in Europe. These shrimp fisheries are characterized by strong seasonal variations in average landings. Attempts to 'catch and hold' wild adults in land‐based rearing systems have been proven to be very difficult, due to inadequate feed, slow growth and high mortality. In this study, we have optimized design and operation procedures of a small‐scale static larval rearing system for the culture of C. crangon larvae. Focus was on optimizing larval survival via water temperature, feed selection, feeding regime and density. This is the first report that shows that C. crangon larvae can be reared at high densities of 300 larvae L‐1 with high survival of 73.5 (± 5.4)% under laboratory conditions. In these systems, larvae can be fed exclusively Artemia nauplii according to a feeding regime which is adjusted based on major moulting events. Addition of microalgae may further increase survival by 10%. The information gathered during this research can be applied to further optimize larval development in either flow‐through or recirculation systems. [ABSTRACT FROM AUTHOR]

The hydroxyproline content in Crangon crangon tissues from the Gulf of Gdansk (southern Baltic) was determined in males, non-ovigerous females and ovigerous females, depending on the individual body length, the study area (two profiles: Gdynia and Sopot) and the depth of occurrence. Individuals were collected and analyzed from April to August 2008. The research on the migratory species C. crangon indicates that the area and depth of its occurrence do not significantly affect the level of hydroxyproline in the tissues of this animal (p > 0.05). However, certain trends have been observed. Hydroxyproline participates in various life processes of C. crangon and its level in the tissues is significantly correlated with the sex of animals (p < 0.05). In males, hydroxyproline plays a major role in the body growth. Moreover, water temperature significantly affects the hydroxyproline content in males of different body sizes. Ovigerous females use hydroxyproline in the reproductive process. In non-ovigerous females, hydroxyproline participates both in the growth of organisms and in the reproductive period. Hydroxyproline can be an indicator of the collagen level, as well as an important factor in physiological processes. [ABSTRACT FROM AUTHOR]

Abstract Shrimp fisheries worldwide are characterized by considerable high by-catch rates. A promising innovation implemented to reduce the environmental impact in the brown shrimp (Crangon crangon) fishery is the use of electric pulses to stimulate shrimp. In recent years, several of these so called pulse trawls have been used in the North Sea, but limited catch comparisons have been conducted so far. This study is the first in which a direct catch comparison between a traditional beam trawl and a pulse trawl is executed over an entire fishing season. The results illustrate that pulse stimulation enables a discard reduction of small shrimp of up to 35% and a reduction of benthos and fish discards of up to 76%, with no loss of commercial shrimp. In addition, contact of the groundgear with the seabed is reduced by using a straight bobbin rope with less bobbins. Therefore, on conditions of associated management and regulation, pulse trawling is probably the best available alternative to the existing trawl gear to achieve a shrimp fishery with reduced by-catch rates. [ABSTRACT FROM AUTHOR]

The article introduces a series of papers published within the issue, including one on the use of metabarcoding of gut contents to establish the diet of the brown shrimp, Crangon crangon, another on the prey of the wolf spider and a paper on associations between birds and feather mites determined by DNA metabarcoding.

A thorough understanding of ecological networks relies on comprehensive information on trophic relationships among species. Since unpicking the diet of many organisms is unattainable using traditional morphology‐based approaches, the application of high‐throughput sequencing methods represents a rapid and powerful way forward. Here, we assessed the application of DNA metabarcoding with nearly universal primers for the mitochondrial marker cytochrome c oxidase I in defining the trophic ecology of adult brown shrimp, Crangon crangon, in six European estuaries. The exact trophic role of this abundant and widespread coastal benthic species is somewhat controversial, while information on geographical variation remains scant. Results revealed a highly opportunistic behaviour. Shrimp stomach contents contained hundreds of taxa (>1,000 molecular operational taxonomic units), of which 291 were identified as distinct species, belonging to 35 phyla. Only twenty ascertained species had a mean relative abundance of more than 0.5%. Predominant species included other abundant coastal and estuarine taxa, including the shore crab Carcinus maenas and the amphipod Corophium volutator. Jacobs' selectivity index estimates based on DNA extracted from both shrimp stomachs and sediment samples were used to assess the shrimp's trophic niche indicating a generalist diet, dominated by crustaceans, polychaetes and fish. Spatial variation in diet composition, at regional and local scales, confirmed the highly flexible nature of this trophic opportunist. Furthermore, the detection of a prevalent, possibly endoparasitic fungus (Purpureocillium lilacinum) in the shrimp's stomach demonstrates the wide range of questions that can be addressed using metabarcoding, towards a more robust reconstruction of ecological networks. [ABSTRACT FROM AUTHOR]

Given their positioning and biological productivity, estuaries have long represented key providers of ecosystem services and consequently remain under remarkable pressure from numerous forms of anthropogenic impact. The monitoring of fish communities in space and time is one of the most widespread and established approaches to assess the ecological status of estuaries and other coastal habitats, but traditional fish surveys are invasive, costly, labour intensive and highly selective. Recently, the application of metabarcoding techniques, on either sediment or aqueous environmental DNA, has rapidly gained popularity. Here, we evaluate the application of a novel, high‐throughput DNA‐based monitoring tool to assess fish diversity, based on the analysis of the gut contents of a generalist predator/scavenger, the European brown shrimp, Crangon crangon. Sediment and shrimp samples were collected from eight European estuaries, and DNA metabarcoding (using both 12S and COI markers) was carried out to infer fish assemblage composition. We detected 32 teleost species (16 and 20, for 12S and COI, respectively). Twice as many species were recovered using metabarcoding than by traditional net surveys. By comparing and interweaving trophic, environmental DNA and traditional survey‐based techniques, we show that the DNA‐assisted gut content analysis of a ubiquitous, easily accessible, generalist species may serve as a powerful, rapid and cost‐effective tool for large‐scale, routine estuarine biodiversity monitoring. [ABSTRACT FROM AUTHOR]

Heat-induced color changes of crustaceans are commonly described as the release of astaxanthin. In this study on Crangon crangon , it was found that astaxanthin plays a minor role in the (dis)coloration. By LC-HRMS, two polar, process dependent pigments were found. One pigment was identified as riboflavin and one as drosopterin (level-2 certainty). Thermal treatments had highest effect on drosopterin concentration changes and were chosen as indicator for a kinetic study of heat-induced color changes. The kinetic data fitted a consecutive step model ( r 2  = 0.971), including a first step in which drosopterin was released ( k d,85°C  = 0.95 ± 0.09 min −1 ; Ea d  = 105 ± 4 kJ/mol) and a second step where drosopterin is degraded ( k b,85°C  = 0.02 ± 0.002 min −1 ; Ea b =  190 ± 15 kJ/mol). The kinetic model shows that shrimp should be heated at lower temperatures (<80 °C) than the heating temperatures used by fishermen (86–101 °C), creating opportunities for quality optimization. Therefore, this study delivers essential information needed in a comprehensive quality optimization study of the cooked brown shrimp. [ABSTRACT FROM AUTHOR]

Brown shrimps (Crangon crangon) occur in high densities in the southern North Sea and support a large, but so far unmanaged fishery with >500 vessels. Cohort-based stock assessment is not possible, and catch per unit effort from scientific surveys and commercial landings are the only variables collected. Landings per unit effort are currently used to approximate the state of stock and to trigger catch restrictions, but, although decisive in interpreting unit catches or landings, factors affecting catch rates are rarely understood. Using data from two long-term (1997–2010) scientific surveys conducted in autumn and winter, respectively, in the southern North Sea and from a vertically resolving stow net deployed at two stations in the German Wadden Sea (2005–2007), we investigate the effects of season, reproductive state, size, tidal state, daylight, and water depth on catch rates of brown shrimp. Log-linear random intercept models revealed an influence of all factors examined on the catch rate. Depth had a clear effect on the composition of size and reproductive state, supporting the hypothesis that brown shrimp utilize selective tidal stream transport to migrate to depths preferred during certain periods within their life cycle. The vertical distribution of brown shrimp across the water column revealed that on average two thirds to three quarters of the brown shrimps were located above reach of the standard shrimp catching gear. Our findings indicate that multiple factors and interactions affect catch rates of brown shrimp and, thus, need to be accounted for when interpreting unit catches or landings for management purposes. We suggest that brown shrimps are not primarily demersal, and that stock size estimates solely relying on beam trawl data may underestimate the true density of shrimps per area. [ABSTRACT FROM AUTHOR]

Abstract: Despite electric pulse fishing being regarded as a promising environmentally friendly fishing method, very little is known about possible negative effects on early life stages of bottom‐dwelling species such as Sole Solea solea. Electrotrawling for brown shrimp Crangon crangon is increasingly used in shallow coastal zones and estuaries of the southern North Sea. As these fishing grounds are often important nurseries and spawning areas for various marine species, electrotrawling could therefore harm inhabiting fishes during their early life stages. Hence, this research aims to investigate the effect of electric pulses used to catch brown shrimp on the survival and development of Sole embryos and larvae. Exposure of Sole embryos at 2 d postfertilization and larvae at 11 d posthatching to pulsed DC used to catch brown shrimp did not result in a lower survival 8 d after exposure. Additionally, no differences in yolk sac resorption and morphometric length measurements of the notochord, muscle, eye, and head were observed in the developing larvae. [ABSTRACT FROM AUTHOR]

Crangon crangon bacilliform virus (CcBV) was first discovered in 2004 in European brown shrimp ( Crangon crangon ) caught along the English coast. This study describes a duplex PCR assay developed for the detection of CcBV, based on amplification of the lef-8 gene (211 bp) of CcBV and the E75 gene (105 bp) of C. crangon as an internal amplification control. The lef-8 and E75 primer pairs were designed based on preliminary genome sequencing information of the virus and transcriptomic data available for C. crangon , respectively. Sequencing of the resulting amplicons confirmed the specificity of this PCR assay and sequence analysis of the lef-8 fragment revealed amino acid identity percentages ranging between 31 and 42% with members of the Nudiviridae , proposing that CcBV may reside within this family. Finally, the duplex PCR assay was applied to samples of C. crangon hepatopancreas tissue collected along the Belgian coast to screen for the presence of CcBV. The prevalence of CcBV averaged 87%, which is comparable to previous reports of high prevalence, based upon histological analysis, in shrimp collected along the English coast. Development of a specific and sensitive PCR assay to detect CcBV will provide a useful tool for future aquaculture and research programs involving C. crangon . [ABSTRACT FROM AUTHOR]

The prevalence of black spot shell disease is increasing among marine crustaceans worldwide. Rising seawater temperatures – often stressful for ectothermic species – are assumed to enhance the occurrence of shell disease. In the North Sea > 50% of local populations of the brown shrimp ( Crangon crangon ) are affected by the disease. While fisheries are suffering because diseased crustaceans are barely merchantable, the impact of shell disease on life history traits of crustaceans is little understood. To determine the role of temperature on the development of black spots and its implications for survival and physiology in the brown shrimp, a prolonged (3 months) thermal stress experiment was performed. We measured the increment of shell disease and the effect of molting in shrimps kept at control (15 °C = equivalent to the seafloor temperature in the North Sea during sampling) and increased temperature (20 °C = according to predictions for the end of the century). The resting metabolic rate was analyzed to determine the physiological state of diseased compared to non-diseased animals. In the present study, the warmer temperature in the range of 20 °C did not increase the spot size of shell disease and no differences were observed between the two temperatures. The process of molting thereby seemed to diminish and in most of the cases even completely remove the signs of shell disease. At 15 °C but not at 20 °C, metabolic rate was reduced in diseased in contrast to healthy individuals. This study showed that shell disease might lead to a higher mortality rate and an impairment of the physiological state in C. crangon . [ABSTRACT FROM AUTHOR]

Thermoregulation in aquatic ectotherms is a complex behavioral pattern that is affected by various biotic and abiotic factors with one being salinity. Especially in coastal and estuarine habitats, altering levels of salinity involve osmoregulatory adjustments that affect total energy budgets and may influence behavioral responses towards temperature. To examine the effect of salinity on behavioral thermoregulation in a marine evertebrate ectotherm, we acclimated juvenile and sub-adult common brown shrimp ( Crangon crangon , L.) to salinities of 10, 20 and 30 PSU and investigated their thermal preference in an annular chamber system using the gravitational method for temperature preference determination. Thermal preference of individual brown shrimp was considerably variable and brown shrimp selected a wide range of temperatures in each level of salinity as well as within individual experimental trials. However, salinity significantly affected thermal preference with the shrimp selecting higher temperatures at 10 and 20 PSU when compared to 30 PSU of salinity. Body size had no effect on thermal selection and did not interact with salinity. Temperature preference differed by sex and male shrimp selected significantly higher temperatures at 10 PSU when compared to females. The results show that salinity strongly affects thermal selection in brown shrimp and confirms the strong interrelation of temperature and salinity on seasonal migratory movements that has been previously derived from observations in the field. In the field, however, it remains unclear whether salinity drives thermal selection or whether changes in temperature modify salinity preference. [ABSTRACT FROM AUTHOR]

Self-regulation is now widely regarded as an effective mechanism for collective action aimed at sustainable management of common pool resources. The brown shrimp (Crangon crangon) fishing industry in the Netherlands has been working on the implementation of a self-management strategy since 2007, as part of its ambition to get certified to the Marine Stewardship Council standard. Part of the self-management strategy is the development of a harvest control rule for reducing fishing effort when catches are low. Until recently, these attempts failed. The failure of the initiatives for self-management is examined within Ostrom's nested framework for understanding institutions for managing resource use. This framework emphasises the importance of strong vertical embeddedness of institutional arrangements for resource (co)management. Our analysis shows that, despite a strong vertical embeddedness, mismatches between different institutional frameworks at the same level (horizontal interaction) affect the performance of self-management at the organizational level. This inhibits the resource users' collective actions to self-manage their brown shrimp fishery, leading to a potential commons tragedy. [ABSTRACT FROM AUTHOR]

To optimize the quality of cooked brown shrimp ( Crangon crangon ), quantitative data on the influence of all relevant process parameters (treatment time, temperature, NaCl concentration) on several quality attributes are required. Surprisingly, kinetic data and models on heat induced quality changes of brown shrimp are scarce. In this study, the denaturation of muscle proteins was studied by differential scanning calorimetry. The thermal denaturation kinetics of actin, the most heat resistant muscle protein, were determined and showed a first order decay with k 72 °C = 0.038 ± 0.001 min −1 and Ea = 388 ± 7.3 kJ/mol. Spiking experiments showed that NaCl (concentrations in the range from 1 to 5% NaCl) had a negligible influence on the actin thermal stability. The kinetic data obtained can be used to quantitatively evaluate the doneness of cooked shrimp. [ABSTRACT FROM AUTHOR]

The high level of cadmium in the abdominal muscle of the brown shrimp Crangon crangon is due to the serious pollution of the water in the Gulf of Gdansk. The inhibition of malic enzyme (ME) activity by cadmium, and in consequence the reduced formation of NADPH, could interfere with cellular mechanisms for detoxifying the organism and reducing oxidative stress. The reduced glutathione (GSH) concentration in the abdominal muscle of C. crangon was calculated to be 5.8 mM. The objective of this study was to evaluate the part played by GSH in the effect of cadmium on the activity of NADP-dependent malic enzyme from abdominal muscles of brown shrimps. This enzyme is activated by certain divalent cations (Mg, Mn). The results demonstrate that cadmium inhibits ME activity from shrimp muscle, and that GSH and albumin can reduce this cadmium-inhibited NADP-dependent malic enzyme activity.

Spatial distributions of Cu, Pb, Cd, Ni and Zn concentrations in brown shrimps Crangon crangon (Linnaeus, 1758) collected on a cruise of FRV Walther Herwig III to the southern North Sea in January 2004, were investigated on a scale of 18 x 18 km to evaluate the range of spatial autocorrelations for the different variables under study. Semivariogram models obtained by geostatistical procedures indicated a distinct increase in variability for most variables with sampling distance. Only if samples are taken at distances above the estimated values for the practical range of the semivariogram can stochastic independence of the data be assumed. These are 6.6 km for Cd, 3.0 km for Ni and 5.2 km for Pb. Contour plots revealed a clear coincidence of high values for Cd, Ni and Pb with low shrimp mean body wet weight. Nevertheless, spatial autocorrelations were rather weak, since classical and geostatistical population estimates for the means and the 95% confidence intervals were in good agreement. The low detected concentrations of Pb in C. crangon were in good agreement with reported data for decapod crustaceans from other regions. For Zn reported values were distinctly below our 95% confidence intervals, while for Cu they were slightly above and for Cd distinctly above concentrations in C. crangon from this study. For Ni no comparative values exist. We conclude that with this integrated biomonitoring approach metal concentrations could be assessed more precisely and relations between biotic and abiotic variables could be evaluated.

The population structure, growth, distribution and secondary production of the brown shrimp Crangon crangon (L. 1758) were examined between June 2003 and August 2005 at five stations in the Mondego Estuary, Portugal, using a 2-m beam trawl. Occurrence of immature shrimps suggested almost continuous reproduction with two main recruitment periods in November and March/April; this recruitment pattern is unique and represents a latitudinal transition in the species’ life cycle. Severe drought in winter 2004 caused spatial shifts along the north arm of the estuary regarding post-larval settlement in spring 2005. Mean growth of all cohorts was 0.06 mm TL day-1, much lower than rates calculated elsewhere. Secondary production (P) of C. crangon was estimated at 4.6 mg AFDW m-2 y-1 (P/B– ratio of 8.7) in 2003/2004 and at 2.4 mg AFDW m-2 y-1 (P/B– ratio of 10.9) in 2004/2005. High abundances of individuals, predominantly juveniles, were observed in spring/summer with peaks in June 2003, April 2004 and July 2005. This study shows that this species dynamics must be analysed in a latitudinal context, meaning that the contribution of each component of the systems can vary according to environmental and climate variables.

Large-scale storage of CO2within sub-sea geological formations is a viable option for reducing the volume of this greenhouse gas released directly to the atmosphere from anthropogenic activities. Risks to benthic marine life following possible leakage of gas through the seabed from this carbon capture and storage (CCS) initiative are not yet well established. This study examined behavior (activity patterns) in brown shrimp (Crangon crangon), exposed to a range of reduced seawater pH conditions (7.6, 7, or 6.5) simulating leakage scenarios of varying scales. Brown shrimp have an endogenous rhythmicity associated with their activity, which dictates they are most active during hours of darkness, presumably as protection against vision-dependent predators. This endogenous rhythm in activity continues to be expressed when shrimp are held under constant low-light conditions in the lab and provides an ecologically relevant endpoint to measure when examining the influence of reduced pH on the behavior of these animals. No marked differences in activity pattern were observed between control shrimp maintained at pH 8.1 and those at pH 7.6. However, changes in activity were evident at pH 7 and pH 6.5, where significant shifts in timing and intensity of activity occurred. There was an unexpected increase in activity within periods of expected light, probably signaling efforts by shrimp to migrate away from reduced seawater pH conditions. The loss of this important member of the benthic community due to migration may have important consequences for many of the resilient species that remain. [ABSTRACT FROM PUBLISHER]

Ectothermic organisms rely on behavioral thermoregulation to modulate their body temperature and the final thermal preferendum (FTP) paradigm (FTPP) postulates that a given species holds a species-specific FTP. The FTPP, however, has been challenged by a considerable amount of recent findings on vertebrate ectotherms, indicating that the FTP is not as static as originally postulated but can be modulated by various factors. In contrast to vertebrates, evidence from invertebrate ectotherms is far more limited. To test for the validity of the FTPP and to study whether behavioral thermoregulation in a marine invertebrate varies seasonally, thermal preferenda of the common brown shrimp ( Crangon crangon , L.) were determined through a 14 month period. Thermal preferenda of males and females of different size groups were measured in an annular chamber system (4–25 °C) using the gravitational method for thermal preference testing. The results revealed that brown shrimp behaviorally selected a wide range of temperatures and did not show a single or constant thermal preferendum. Thermal preference was modulated following a seasonal pattern suggesting the existence of distinct seasonal preference zones rather than a species-specific preference temperature. Brown shrimp selected low temperatures during winter, however, a difference of 5 °C in preferred temperature was observed between a cold and a relatively mild one. Highest thermal preferenda did not coincide with field water temperatures but were observed after field water temperatures exceeded the annual temperature peak. Besides season, body size of brown shrimp significantly affected thermal selection and small individuals selected higher temperatures compared to large ones. A significant interaction of body size and water temperature at which the shrimp were caught was detected. The study further provides evidence that cohort identity as well as female reproductive state may affect thermal preference as well. The results of the study reveal that thermal selection in brown shrimp is complex, not static and that preference temperature can be modulated by various factors, representing the first evidence for a marine invertebrate ectotherm. [ABSTRACT FROM AUTHOR]

To optimize product quality of the cooked brown shrimp ( Crangon crangon ), quantitative data on the influence of all relevant process parameters (treatment time and temperature) on several quality attributes is required. Surprisingly, kinetic data and models on heat induced inactivation of important endogenous spoilage enzymes of the brown shrimp are not available today. In this study the thermal inactivation kinetics of the most important spoilage enzymes, proteases and polyphenoloxidase (PPO), were determined from isothermal heat treatments of enzyme extracts of the cephalothorax. For both enzymes, inactivation kinetics showed first order decay(s). Proteases showed two distinct stability fractions. A labile fraction, representing 42 ± 2% of the total activity with k l ,60 °C = 0.94 ± 0.14 min −1 and E a , l = 178 ± 8.5 kJ/mol, and a stable fraction, representing 58 ± 2%, with k s ,60 °C = 0.020 ± 0.002 min −1 and E a , s = 155 ± 7.0 kJ/mol. PPO showed a single fraction with k 60 °C = 1.58 ± 0.02 min −1 and E a = 161 ± 2.2 kJ/mol. Based on these results, the proteolytic activity, in particular the thermostable fraction, should be considered as a target in thermal processing of brown shrimp in relation to enzyme induced product quality changes during storage. [ABSTRACT FROM AUTHOR]

This study was performed to comprehensively reveal the composition of the microbial community of commercially cooked and machine peeled brown shrimp ( Crangon crangon ), packaged and stored under modified atmosphere without added preservatives. Three independent experiments, using both culture-dependent and culture-independent methods, were conducted over an entire shrimp season. Initial total aerobic psychrotrophic bacterial counts (APC) were relatively high on several general media ranging between 5.4 and 6.4 log cfu g −1 . After 7 days of storage at 4 °C, samples were considered microbiologically spoiled with no apparent difference in APC between samples from different periods. The dominant microbiota present after 7 days of storage was assessed by (GTG) 5 analysis of selected colonies and 16S rRNA gene sequence analysis. The dominant organism on general media was Arthrobacter bergerei , whereas on more selective media Shewanella putrefaciens , Brochothrix thermosphacta and Vagococcus salmoninarum were most abundant. Culture-independent denaturant gradient gel electrophoresis (DGGE) and Illumina next generation sequencing revealed Carnobacterium as a dominant genus at day 7 throughout the year, together with members of Shewanella and Psychrobacter . The differences in relative abundance of dominant genera between different months also indicated a possible seasonal influence on the microbial community. It could be concluded that the same major groups of spoilage bacteria were retrieved by culture dependent and independent approaches, but their relative abundance differed. [ABSTRACT FROM AUTHOR]

Ecosystem engineers can considerably affect the community composition, abundance and species richness of their environment. This study investigates the existence of positive or negative feedbacks of species that compose the community in intertidal biogenic reefs constructed by the ecosystem engineer Lanice conchilega . This tubeworm creates attractive nursery and feeding grounds for the predatory brown shrimp Crangon crangon , while at the same time is preyed upon by C. crangon . The effect of the predation pressure exerted by C. crangon on the bioirrigation and feeding activity of the tubeworm is up until now unknown and it is hypothesised that these activities are affected by the high densities of C. crangon in the reefs. A mesocosm experiment was set up to investigate the effects of predation pressure on the bioirrigation and feeding activity of L. conchilega in the i) absence; ii) restricted presence; and iii) unrestricted presence of C. crangon . Bioirrigation was quantified by the decrease of an artificially introduced bromide (Br − ) tracer, while feeding activity was measured from the incorporation of 13 C via stable isotope analysis. The bioirrigation rate of the L. conchilega reef equalled about 30 L·m − 2 ·d − 1 and was not affected by the presence of the predator. The food uptake of the tubeworm was however about three times lower in the unrestricted presence of C. crangon , presumably due to the retraction of the worm's body and tentacles in its tube induced by physical contact with the predator. Notwithstanding the impacted food uptake of L. conchilega , the tubeworm maintains its functional role in the presence of predators in soft-bottom intertidal areas. [ABSTRACT FROM AUTHOR]

The European brown shrimp, Crangon crangon, is a highly valued commercial species fished in the north-eastern Atlantic, especially the North Sea. The shrimp fisheries are mainly coastal and exert high pressures on the local ecosystems, including estuaries. The culture of the species provides an alternative to supply a niche market (large live/fresh shrimps) in a sustainable manner. However, after more than a century of biological research on this species, there is still little knowledge on its optimal rearing conditions. C. crangon remains a difficult species to keep alive and healthy for an extended period of time in captivity. This review is based on a comprehensive literature search and reflects on the current status of experimental rearing techniques used for this species, identifies the problems that compromise the closing of the life cycle in captivity and provides examples on how these problem issues were solved in the culture of commercial shrimp species or other crustaceans. The ability to consistently produce highquality offspring could initiate the commercial production of this valuable shrimp. A further advantage of the ability to consistently produce high-quality offspring of this species would facilitate research on the development of new bioassays with this ecologically and economically important species in a wide variety of biochemical and physiological studies. [ABSTRACT FROM AUTHOR]