Brown Shrimp Research Articles

Coping with the “dirt”: brown shrimp and the microplastic threat

Microplastic pollution is an emerging threat to marine biota. Uptake of microplastics can impair nutrition and affect the performance of organisms. However, the vulnerability to microplastics seems to vary between species for yet widely unexplored reasons. We investigated the stomach content of the brown shrimp, Crangon crangon, from the southern North Sea and performed feeding experiments and anatomical studies of the digestive organs to comprehend the distribution of fluorescent microparticles within the shrimp. Shrimp collected in their natural environment contained between 51 and more than 3,000 sand grains and fragments of bivalve shells in their stomachs. Sand grains may have been ingested to exploit the associated biofilm or to support maceration of food. Bivalve shell fragments were particularly abundant in summer when shrimp fed on freshly settled mussels. Shrimps' stomach can be cleaned from ingested particles by regurgitation. In an experimental approach, we administered fluorescent microbeads of 0.1, 2.1, and 9.9 μm diameter. Only the smallest particles (0.1 μm) entered the midgut gland, which is the principal site of nutrient resorption in crustaceans. A fine-meshed chitinous filter system in the stomach of the shrimp prevents the passage of particles larger than about 1 μm. C. crangon appears well adapted to handle natural microscopic particles. This trait might also be advantageous in coping with microplastic pollution.

Shell disease does not affect biochemical profiles of the North Sea brown shrimp Crangon crangon.

The brown shrimp Crangon crangon is a key component of the North Atlantic coastal food web and an important target species for the fishery economy. As the brown shrimp contains large amounts of protein and essential fatty acids, its consumption makes it a beneficial choice for humans. Commercially harvested crustaceans like C. crangon are frequently affected by bacterial shell disease, with necrotizing erosions and ulcerations of the cuticle. To determine whether shell disease influences the nutritional value of C. crangon, total protein and lipid contents, as well as fatty acid compositions of muscle tissue and hepatopancreas, together with the hepatosomatic index, were examined in healthy and affected individuals. The biochemical composition of the tissues did not differ significantly between the 2 groups. Also, the hepatosomatic index, as an indicator of energy reserves in shrimps, was similar between healthy and affected animals. Our results indicate that the nutritional value of C. crangon is not affected by shell disease, as long as it remains superficial as in the present study.

Oxygen-dependence of upper thermal limits in crustaceans from different thermal habitats.

The critical thermal maximum (CTMAX) is the temperature at which animals exhibit loss of motor response because of a temperature-induced collapse of vital physiological systems. A central mechanism hypothesised to underlie the CTMAX of water-breathing ectotherms is insufficient tissue oxygen supply for vital maintenance functions because of a temperature-induced collapse of the cardiorespiratory system. The CTMAX of species conforming to this hypothesis should decrease with declining water oxygen tension (PO2) because they have oxygen-dependent upper thermal limits. However, recent studies have identified a number of fishes and crustaceans with oxygen-independent upper thermal limits, their CTMAX unchanged in progressive aquatic hypoxia. The previous studies, which were performed separately on cold-water, temperate and tropical species, suggest the oxygen-dependence of upper thermal limits and the acute thermal sensitivity of the cardiorespiratory system increases with decreasing habitat temperature. Here we directly test this hypothesis by assessing the oxygen-dependence of CTMAX in the polar Antarctic krill (Euphausia superba), as well as the temperate Baltic prawn (Palaemon adspersus) and brown shrimp (Crangon crangon). We found that P. adspersus and C. crangon maintain CTMAX in progressive hypoxia down to 40mmHg, and that only E. superba have oxygen-dependent upper thermal limits at normoxia. In E. superba, the observed decline in CTMAX with water PO2 is further supported by heart-rate measurements showing a plateauing, and subsequent decline and collapse of heart performance at CTMAX. Our results support the hypothesis that the oxygen-dependence of upper thermal limits in water-breathing ectotherms and the acute thermal sensitivity of their cardiorespiratory system increases with decreasing habitat temperature.

Occurrence of Penaeus aztecus, Ives, 1891 (Crustacea: Decapoda: Penaeidae) in the coastal water of Alexandria, Egypt

A sample of 347 specimens of the northern brown shrimp Penaeus aztecus, a western Atlantic species, was collected from July 2019 to June 2020 by local bottom trawlers off two fishing areas, Abu-Qir Bay and Ma’deya, east of Alexandria Coast, Egypt. The species identification was confirmed by morphological and genetic characters. Some aspects of the species’ morphometry and its monthly abundance were briefly discussed. The collected adults were observed from May to November with higher percentage of occurrence in August (29% of total shrimp catch). Sex ratio was 1: 1.2 (F: M). The total length of the adult specimen ranged from 91 mm to 210 mm. COI sequences gave a maximum identity of 99.56% with P. aztecus from Texas and USA, and 99.44% with species from the Eastern Mediterranean. The genetic distance among the studied species from Egypt, USA and the Eastern Mediterranean ranged from 0.2 to 0.7%. The results of this study suggest that P. aztecus may become a new resource for coastal Mediterranean shrimp fisheries.

Effects of the antidepressant fluoxetine on pigment dispersion in chromatophores of the common sand shrimp, Crangon crangon: repeated experiments paint an inconclusive picture

The effects of antidepressants in the environment are starting to generate considerable interest due to the fact that neurotransmitters influence a range of biological processes. Crypsis is an important behavioural and physiological response in many crustaceans modulated by monoamine and pigment dispersing/concentrating hormones. This study aimed to develop a test methodology and investigate the effects of the selective serotonin reuptake inhibitor (SSRI), fluoxetine, on a chromatophore index and overall carapace ‘darkness’ in the common sand shrimp Crangon crangon. Adult shrimp were exposed for either 1 h, 1 day or 1 week across a range of nominal fluoxetine concentrations (10 ng/L, 100 ng/L and 1000 ng/L) and the chromatophore index or carapace percentage ‘darkness’ was recorded following 30 min on white and black substrates. These experiments were repeated three times using different specimens. Animals became significantly darker (~20%) on darker background and lighter on light backgrounds as one might expect. However, time periods over which the animals were recorded had a significant impact on the colouration suggesting habituation to laboratory conditions. Fluoxetine exposure came up as a significant factor in two of the three trials for the chromatophore index but the results was inconsistent between trials. There was a high degree of correlation between the chromatophore index and the percentage darkness analyses however, there was no significant effects for fluoxetine exposure with the percentage darkness data. We conclude that the effects on antidepressants on colour change remain inconclusive from these experiments and we discuss potential areas to improve the repeatability of the experiments.

Testing a size sorting grid in the brown shrimp (Crangon Crangon Linnaeus, 1758) beam trawl fishery

The North Sea brown shrimp (Crangon crangon Linnaeus, 1758) fishery became Marine Stewardship Council (MSC) certified in 2017. As part of the certification, the fishermen proposed to incrementally increase the mesh size of the codend used from 22 mm to 26 mm. As this increase in mesh size could result in a substantial loss of marketable sized brown shrimp (shrimp with total length equal or higher than 50 mm), a combination of a size sorting grid with a bar spacing of 6 mm and a 22 mm codend was proposed by the Danish fishermen as a possible alternative to the increase in codend mesh size. The objective of the proposed gear was to release shrimp smaller than the marketable size before they reach the codend, while potentially limiting the loss of marketable sized shrimp. Therefore, the aim of this study was to investigate the size selective performance of brown shrimp in the above-mentioned gears. The results showed that the grid reduced catches of shrimp under the marketable size of 50 mm. Moreover, the combination of the grid and a 22 mm diamond mesh codend, with an estimated L50 of 44.9 mm and a selection range of 15.6 mm, had an overall selective performance similar to that of a 26 mm diamond mesh codend, both for shrimps under and above the marketable size.

Diet of Striped Bass in the Southern Gulf of St. Lawrence (Canada) with Emphasis on the Spring Spawning Aggregation

The southern Gulf of St. Lawrence (sGSL) population of Morone saxatilis (Striped Bass) increased over 50 fold between the mid-1990s and 2013–2015, which led to interest in how their feeding might affect populations of commercially and recreation-ally important species. Information on the feeding habits of Striped Bass in all Canadian waters is scarce; therefore, a large number (n = 2220) of sGSL Striped Bass (19–86 cm fork length [FL]) stomachs were collected seasonally (2013–2015) in the Miramichi Estuary (where almost the entire population of individuals >30 cm FL aggregates during spring) and smaller estuaries that empty into the sGSL (summer only), by means of trap nets and by angling. Striped Bass collected during May–early June fed almost exclusively upon Osmerus mordax (Rainbow Smelt) but also consumed a few juvenile Salmo salar (Atlantic Salmon). Striped Bass collected in trap nets during 5–30 June mainly ate a mix of Alosa pseudoharengus (Alewife) and A. aestivalis (Blueback Herring); those collected by angling consumed aquatic insects and Crangon septemspinosa (Sevenspine Bay Shrimp). Striped Bass collected during July–September (30–45 cm FL) ate C. septemspinosa, Palaemon vulgaris (Common Grass Shrimp), and small estuarine fishes. The autumn sample was too small to be considered representative of the population; nevertheless, these fish (32–73 cm FL) ate juveniles of Microgadus tomcod (Atlantic Tomcod), Urophycis tenuis (White Hake), and Gadus ogac (Greenland Cod). The data collected herein would permit reasonable estimates of prey consumed by the sGSL Striped Bass population during spring and, for fish <45 cm total length, during summer, but estimation of annual prey consumption by the sGSL Striped Bass population requires additional data.

Data Recovery from Old Filing Cabinets: Seasonal Diets of the Most Common Demersal Fishes in the Miramichi River Estuary (Atlantic Canada), 1991–1993

A recent data-recovery exercise uncovered a large amount of stomach-content data (n = 8209) from mainly demersal fishes collected seasonally in the Miramichi River Estuary, southern Gulf of St. Lawrence (sGSL), 1991–1993. Of the demersal species captured, all but Pleuronectes putnami (Smooth Flounder) represent transient species. Within the estuary, stomach samples were collected from all species (except Osmerus mordax [Rainbow Smelt]) captured by trawling and in commercial trap nets. Rainbow Smelt stomachs were collected during trawl surveys (May through October) in nearby coastal waters. The summer diet analyses were limited to Smooth Flounder (small bivalve specialist), Pseudopleuronectes americanus (Winter Flounder), and Rainbow Smelt. Many juvenile Urophycis tenuis (White Hake) entered the estuary during late September to feed and then departed during November. Numerous Gadus macrocephalus (Greenland Cod), Myoxocephalus scorpius (Shorthorn Sculpin), Winter Flounder, juvenile Clupea harengus (Atlantic Herring), Microgadus tomcod (Atlantic Tomcod), Rainbow Smelt, Morone saxatilis (Striped Bass), and Zoarces americanus (Ocean Pout) entered the estuary during autumn to overwinter, spawn, and feed. Winter Flounder, Smooth Flounder, Striped Bass, and Atlantic Herring fasted during winter. Crangon septemspinosa (Seven-spined Bay Shrimp) was the most important invertebrate prey (up to 95% of total prey mass) of all transient species. Large specimens of Greenland Cod, Shorthorn Sculpin, Ocean Pout, and White Hake also ate substantial numbers of small Rainbow Smelt, Atlantic Herring, Striped Bass, and Atlantic Tomcod. When combined with published data for the adjacent coastal zone, C. septemspinosa represents a nexus in 2 food webs and fits the description of a keystone species for the sGSL coastal zone and adjacent estuaries.

Identification of Species in Commercial Frozen Shrimp Meat in Taiwan

Attempts were made to identify species in commercial frozen shrimp meat samples collected in Taiwan. First, approximately 20 fresh specimens of each of the 10 common commercial shrimp species were identified by morphological methods. A 401 to 407-bp fragment of the cytochrome b gene was amplified from the shrimp meat by polymerase chain reaction (PCR) using the primer pair UCYTB151F/270R. By comparing the gene sequences and PCR-restriction fragment length polymorphism (RFLP) maps obtained using the endonucleases Alu I, Ssp I and Hae III, the 10 species of shrimp could be successfully differentiated. The PCR-RFLP method was proved applicable for the species identification of 10 marketed shrimp samples.

Quantitation of Total Protein Content in Some Common Edible Food Sources by Lowry Protein Assay

The nutrient value or quality of different proteins varies due to amino acid composition, ratios of essential amino acids, vulnerability to hydrolysis during digestion, source, and the effects of transforming. To enhance the biological activity of proteins, better gripping is needed for the various correlated parameters that influence their nutrient value. This research article attempts to contribute to this effort. It analyzes the Lowry method used for protein quantity evaluation. Recent studies on the nutrient quality of 11 common protein sources including oyster mushroom (Pleurotus ostreatus), white button mushroom (Agaricus bisporus); chicken (Gallus gallus domesticus); black Bengal goat (Capra hircus); brown shrimp (Metapenaeus monoceros); Mola carplet (Ambylpharyngodon mola), Rohu fish (Labeo rohita), Reba carp (Cirrhinus reba), slender rasbora (Rasbora daniconius), banded gourami (Trichogaster fasciata); and egg albumin are evaluated. The highest amount of protein present in brown shrimp, i.e., 85.982 mg/mL. This study is intended to trigger interest in the use of new protein sources for nourishing the booming world population.

New Records of Penaeus aztecus Ives, 1891 from the Eastern Ionian Sea

Brown shrimp Penaeus aztecus Ives, 1891 seems to be well adapted in the Ionian Sea since its first occurrence in the coastal zone of the island of Corfu during 2013. In the current work, we present additional new records from Argostoli Gulf (Cephalonia Island), Sagiada Bay (Therspotia, NW Greece) and Mesoggi (Corfu Island), which verify the wider distribution of the species. Moreover, direct contacts with shrimpers in the region, suggested that commercial exploitation of the species has been recently established. Although it poses potential threats to the lucrative caramote shrimp (Penaeus kerathurus) populations, which support the income of the fishing communities in the region, the presence of P. aztecus populations represents a new promising fisheries resource.

Molecular aspects of lipid metabolism in the midgut gland of the brown shrimp Crangon crangon.

The brown shrimp, Crangon crangon, is well adapted to the variable environmental conditions in the southern North Sea. It is very abundant, has high reproduction rates, and holds a key position in coastal ecosystems. This species has very low lipid deposits in the midgut gland, suggesting that the main function of the midgut gland is metabolic turnover rather than energy storage. Based on seasonal gene expression studies and established transcriptome data, we investigated key components of lipid metabolic pathways. Gene expression of triacylglycerol lipase, phospholipase, and fatty acid desaturase were analyzed and compared with that of other digestive enzymes involved in lipid, carbohydrate, and protein catabolism. Our results suggest that gene expression of digestive enzymes involved in lipid metabolism is modulated by the lipid content in the midgut gland and is related to food availability. Brown shrimp seem to be capable of using cellular phospholipids during periods of food paucity but high energetic (lipid) requirements. Two of three isoforms of fatty acid binding proteins (FABPs) from the midgut gland involved in fatty acid transport showed specific mutations of the binding site. We hypothesize that the mutations in FABPs and deficiencies in anabolic pathways limit lipid storage capacities in the midgut gland of C. crangon. In turn, food utilization, including lipid catabolism, has to be efficient to fulfill the energetic requirements of brown shrimp.

Culture potentials of brown shrimp, Metapenaeus monoceros (Fab.) under different stocking densities in south-western region of Bangladesh

An experiment was conducted to evaluate the production potentials of brown shrimp, Metapenaeus monoceros under three different stocking densities such as 10, 20 and 30 /m2 in treatments T1, T2 ,and T3 in brackishwater ponds. After 90 days of culture total production was recorded as 577, 608 and 764 kg/ha in T1, T2 and T3 respectively. Total production was significantly higher (p&lt;0.05) in T3 compared to T1 and T2. Net benefit was recorded as BDT 143,109/ha, BDT 121,825/ha and BDT 162,516/ha in T1, T2 and T3 respectively. Cost benefit ratio was 2.23, 1.80 and 1.91 in T1, T2 and T3 respectively. Net benefit in T3 (BDT 162,516/ha) was higher than T1 and T2. The brown shrimp have high rates of growth, together with that they tolerate wide ranges of salinity and environmental parameters, makes them highly attractive for culture purposes.

IDENTIFIKASI JAMUR MIKROSKOPIK DARI TAMBAK UDANG Litopenaeus vannamei SISTEM SEMI-INTENSIF

Litopenaeus vannamei is one of the most common shrimp species cultivated with the semi-intensive system in Indonesia. This system required large food and probiotic input during cultivation and certainly will impact the water quality and the presence of the microbial colony. The unhealthy water circulation will increase microbe pathogen. Fungi is one of ubiquitous microbe that often appears in shrimp pond. The aim of this study is to identify and calculate the biology index from shrimp cultivation ponds. This research was implemented in March 2019 – April 2020. The method of this research is purposive sampling to get the fungi culture from inlet, outlet and rejuvenate shrimp ponds. The identification of fungi was done with macroscopic and microscopic examination. The result found 9 isolates fungi comprised of 8 species. There were 4 fungi identified from the inlet shrimp pond, Aspergillus sp 1, Aspergillus sp 4, Penicillium sp, and Trichoderma sp 2, while from outlet pond were Aspergillus sp 1, Trichoderma sp 1 and from rejuvenating shrimp ponds were Saccharomyces cerevisiae, Trichoderma sp 1 and Penicillium sp. There were no fungi found from L. vannamei, because all of the L. vannamei shrimp in healthful condition.

Sobre a carcinofauna acompanhante na pesca industrial do camarão-rosa na plataforma continental Amazônica

Este trabalho foi realizado com objetivo de quantificar a carcinofauna acompanhante por estação do ano, período do dia e faixa de profundidade na pesca industrial do camarão-rosa na Plataforma Continental Amazônica. O estudo foi realizado a partir de 152 registros de operações de pesca ou arrastos de fundo, sendo 72 na época de chuva (dezembro a maio) e 80 na época de seca (junho a novembro), com duração média de 3,5 ± 1,5 horas, totalizando 532 horas de arrasto, nos meses de julho e setembro de 2010 e março e abril de 2011, entre os estados do Pará e Amapá. Inicialmente a fauna acompanhante foi classificada em cinco grupos: peixes, camarão-rosa, crustáceos, moluscos e outros. Em seguida, foi realizada a triagem das comunidades de crustáceos: caranguejos, portunídeos, camarões, lagostas e estomatópodes, onde cada grupo foi quantificado em peso e número de exemplares. Das amostras coletadas no período do estudo, obteve-se uma relação camarão-rosa/fauna acompanhante na época de chuva de 1:3, e na época de seca de 1:30. A carcinofauna diferiu significativamente entre época do ano e entre faixa de profundidade, mas não entre o período do dia. A relação entre o volume (kg) de camarão-rosa capturado e carcinofauna oscilou muito, com o valor médio de 1:1. Nas pescarias industriais de camarão-rosa na costa norte do Brasil a relação camarão/carcinofauna acompanhante é influenciada pela estação do ano e faixa de profundidade, sendo menos danosa a essa biodiversidade no primeiro semestre de cada ano.

Market Efficiency Indicators in Marine Fish Marketing in Goa, India

The Indian State of Goa has a coastal length of 104 Kms and the State contributes 1.85% to the marine fish production of the country. A study was conducted to assess the market efficiency indicators such as Gross Marketing Margin, Percentage Share of Fisherman in the Consumers Rupee (PSFCR) and the Coefficient of variation. The study revealed that high value fishes such as cobia, silver Whiting, seer fishes, prawns and milk shark recorded a comparatively higher price spread. Varieties which recorded higher PSFCR were speckled prawn (72.86%), cobia (70.31%), seerfish (69.98%), Brown shrimps or ginga prawns (69.43%), pony fish (67.58%) and milk shark (65.61%). At the point of first sales, high value fishes such as cobia, seerfishes, prawns and silver biddy had a co-efficient of variation of less than 10% indicating a higher price stability. High value fishes such as ribbon fishes, seerfishes, cobia, indian white prawn, barracudas, brown prawns, speckled prawns, kadal shrimps and half beaks were among the list of fishes which recorded a low co-efficient of variation of less than 10% at the point of last sales.

Use of a methanolic olive leaf extract (Olea europaea) against white spot virus syndrome in Penaeus vannamei: Comparing the biochemical, hematological and immunological changes

The main goal of this study was to investigate the biochemical, hematological, and immunological impacts of olive (Olea europaea) leaf extract (OLE) in Penaeus vannamei experimentally infected by white spot syndrome virus (WSSV). A total of 160 juvenile whiteleg shrimp (11.1 ± 0.2 g), obtained from a private sector in Hormozgan Province (Iran), were kept for two weeks to acclimatize to conditions in the facility aquarium. The health status of the shrimp was assured by random sampling before experiment action; PCR testing confirmed the absence of common shrimp diseases. Three groups, each consisting of 20 shrimp fed with three different doses of OLE (50, 100, 200 mg/kg of the shrimp biomass), and a positive control group (not feeding with OLE), were all orally subjected to a virus challenge two weeks later. For comparison, three negative control groups with 20 shrimp were fed three different doses of OLE, and another group was fed with a diet lacking OLE. The PCR test confirmed the presence of the WSS virus in the treatment and positive control groups, while the negative control groups did not show any infections. The hemolymph of shrimp was taken on days 1, 8, and 22 from all groups after challenge for evaluation of hemolymph total protein, glucose, oxyhemocyanin (OxH), superoxide dismutase (SOD), phenoloxidase (PO) activity, coagulation time, and total hemocyte count (THC). Results showed that shrimp survival significantly increased up to 65% when fed with high doses of OLE for seven days. The maximum hemolymph total protein and glucose levels significantly belonged to the treatment that was challenged by WSSV without receiving OLE. The present findings indicate WSS infection caused a significant decrease in OxH level compared to that of the control groups. Therapeutic feeding with OLE could significantly decrease the SOD and PO activities, and the hemolymph clotting time. We did not see no remarckable effects of OLE on the total hemocyte count. In conclusion, the various indices studied in this research showed that the olive leaf extract would be useful in the control and prevention of white spot syndrome.

Making the most of available monitoring data: A grid-summarization method to allow for the combined use of monitoring data collected at random and fixed sampling stations

Statistical habitat models, such as spatial generalized linear mixed models (GLMMs) and spatial generalized additive models (GAMs), provide valuable products to habitat assessments and ecosystem-based fisheries management (EBFM) efforts. In particular, derived spatial distribution maps and quantitative relationships of marine organisms to environmental variables (e.g., suitability indices) can be employed to develop or validate ecosystem simulation models. Recent studies fitted spatial GLMMs and spatial GAMs to encounter/non-encounter data collected by different regional monitoring programs that use random sampling designs, so as to enable the production of distribution maps and suitability indices in bulk. However, despite these large efforts, it was not possible to obtain distribution maps for a number of species and life stage combinations, including the juvenile stages of coastal fish species such as croaker (Micropogonias undulatus). In this study, we introduce a grid-summarization method that allows for the combined use of encounter/non-encounter data collected by multiple monitoring programs at random and fixed sampling stations. We demonstrate our grid-summarization method for contrasting species of the western U.S. Gulf of Mexico: red snapper (Lutjanus campechanus), for which data delivered by monitoring programs employing random sampling designs have a satisfactory spatial coverage and the use of monitoring data collected at fixed sampling stations is not necessary; and croaker and brown shrimp (Farfantepenaeus aztecus), for which the combined use of monitoring data collected at random and fixed sampling stations enables or improves the generation of distribution maps. We compare spatial GLMMs and spatial GAMs that rely on the grid-summarization method (“new models”) to spatial GLMMs and spatial GAMs that do not rely on the grid-summarization method (“status-quo models”). We found that the grid-summarization method that allows for the combined use of monitoring data collected at random and fixed sampling stations results in reasonable seasonal distribution maps and suitability indices for the species and life stage combinations (e.g., croaker early juveniles, small brown shrimps) that are undersampled by the monitoring programs that employ random sampling schemes. We also found that the grid-summarization method provides reasonable seasonal distribution maps and suitability relationships for species and life stage combinations (e.g., red snapper adults) for which the status-quo method already provided reasonable results and the combined use of monitoring data collected at random and fixed sampling stations is not necessary. For these species and life stage combinations for which the status-quo method worked well, the choice of the grid-summarization method over the status-quo method depends on whether the fisheries analysts wish to produce smoother distribution maps and whether they target higher predictive accuracy at the expense of lower discrimination accuracy when working with spatial GAMs. Our results suggest that additional monitoring datasets that were previously excluded can be employed by statistical habitat models, thereby enabling generation of distribution maps and suitability indices for a wider range of species, life stage and season combinations.

Exploration of the virome of the European brown shrimp (Crangon crangon)

Crangon crangon is economically a very important species. Recently, promising culture attempts have been made, but a major problem is the uncontrollable mortality during the grow-out phase. As of yet, the life cycle of C. crangon is not closed in captivity so wild-caught individuals are used for further rearing. Therefore, it is important to investigate the virome of C. crangon both in wild-caught animals as in cultured animals. In recent years, next-generation-sequencing (NGS) technologies have been very important in the unravelling of the virome of a wide range of environments and matrices, such as soil, sea, potable water, but also of a wide range of animal species. This will be the first report of a virome study in C. crangon using NGS in combination with the NetoVIR protocol. The near complete genomes of 16 novel viruses were described, most of which were rather distantly related to unclassified viruses or viruses belonging to the Picornavirales, Bunyavirales Nudiviridae, Parvoviridae, Flaviviridae, Hepeviridae, Tombusviridae, Narnaviridae, Nodaviridae, Sobemovirus. A difference in virome composition was observed between muscle and hepatopancreatic tissue, suggesting a distinct tissue tropism of several of these viruses. Some differences in the viral composition were noted between the cultured and wild shrimp, which could indicate that in sub-optimal aquaculture conditions some viruses become more abundant. This research showed that a plethora of unknown viruses is present in C. crangon and that more research is needed to determine which virus is potentially dangerous for the culture of C. crangon.

Polymerase chain reaction as a promising tool for DNA-based diet studies of crustaceans

Studying the diet of crustaceans based on the direct visual inspection of the gut contents can be difficult because they can ingest only a portion of the prey and further crush it into very small pieces, making a very few food items identifiable. Here, the usefulness of molecular methods to identify the species present in the gut contents of two crustaceans, the shore crab Carcinus maenas and the brown shrimp Crangon crangon, was tested. Stomach contents were removed, and their total genomic DNA extracted followed by amplification (PCR) with four specific prey mtDNA primers. Since both crustaceans are opportunistic predators, preying upon around 40 different species, the study was restricted to common potential preys in the sampled area, the Minho Estuary (Portugal): the common goby Pomatoschistus microps, the ragworm Hediste diversicolor, the flounder Platichthys flesus and the peppery furrow shell Scrobicularia plana. After testing the most appropriate methodology for DNA extraction and PCR amplification to detect the presence of each potential prey with positive control samples, the same methodology was applied to the stomach content samples. The molecular methods allowed for detection of the presence of P. microps, P. flesus and H. diversicolor in the stomachs of both crustaceans. Therefore, once potential prey and their availability in the system are known, PCR technique can be an alternative tool to overcome some of the limitations of traditional methods in the study of the crustaceans’ diet, even when stomach contents include a great part of ‘detritus’. This study reflects also the need to develop more tools (primers) to improve the assessment of predator–prey interactions in aquatic ecosytems.