Boreal marine fauna from the Barents Sea disperse to Arctic Northeast Greenland.

As a result of ocean warming, the species composition of the Arctic seas has begun to shift in a boreal direction. One ecosystem prone to fauna shifts is the Northeast Greenland shelf. The dispersal route taken by boreal fauna to this area is, however, not known. This knowledge is essential to predict to what extent boreal biota will colonise Arctic habitats. Using population genetics, we show that Atlantic cod (Gadus morhua), beaked redfish (Sebastes mentella), and deep-sea shrimp (Pandalus borealis) recently found on the Northeast Greenland shelf originate from the Barents Sea, and suggest that pelagic offspring were dispersed via advection across the Fram Strait. Our results indicate that boreal invasions of Arctic habitats can be driven by advection, and that the fauna of the Barents Sea can project into adjacent habitats with the potential to colonise putatively isolated Arctic ecosystems such as Northeast Greenland.

First evidence of microplastic ingestion by fishes from the Amazon River estuary.

This study investigated occurrence of microplastic particles in digestive tracts of fishes from the Amazon River estuary. A total of 189 fish specimens representing 46 species from 22 families was sampled from bycatch of the shrimp fishery. Microplastic particles removed from fish gastrointestinal tracts were identified using Attenuated Total Reflectance - Fourier Transform Infrared (ATR-FTIR). In total, 228 microplastic particles were removed from gastrointestinal tracts of 26 specimens representing 14 species (30% of those examined). Microplastic particles were categorized as pellets (97.4%), sheets (1.3%), fragments (0.4%) and threads (0.9%), with size ranging from 0.38 to 4.16 mm. There was a positive correlation between fish standard length and number of particles found in gastrointestinal tracts. The main polymers identified by ATR-FTIR were polyamide, rayon and polyethylene. These findings provide the first evidence of microplastic contamination of biota from the Amazon estuary and northern coast of Brazil.

Convergent Evolution of the Osmoregulation System in Decapod Shrimps.

In adaptating to different aquatic environments, seawater (SW) and freshwater (FW) shrimps have exploited different adaptation strategies, which should generate clusters of genes with different adaptive features. However, little is known about the genetic basis of these physiological adaptations. Thus, in this study, we performed comparative transcriptomics and adaptive evolution analyses on SW and FW shrimps and found that convergent evolution may have happened on osmoregulation system of shrimps. We identified 275 and 234 positively selected genes in SW and FW shrimps, respectively, which enriched in the functions of ion-binding and membrane-bounded organelles. Among them, five (CaCC, BEST2, GPDH, NKA, and Integrin) and four (RasGAP, RhoGDI, CNK3, and ODC) osmoregulation-related genes were detected in SW and FW shrimps, respectively. All five genes in SW shrimps have been reported to have positive effects on ion transportation, whereas RasGAP and RhoGDI in FW shrimps are associated with negative control of ion transportation, and CNK3 and ODC play central roles in cation homeostasis. Besides, the phylogenetic tree reconstructed from the positively selected sites separated the SW and FW shrimps into two groups. Distinct subsets of parallel substitutions also have been found in these osmoregulation-related genes in SW and FW shrimps. Therefore, our results suggest that distinct convergent evolution may have occurred in the osmoregulation systems of SW and FW shrimps. Furthermore, positive selection of osmoregulation-related genes may be beneficial for the regulation of water and salt balance in decapod shrimps.

New records of the rare pandalid shrimp Plesionika exigua (Rathbun, 1906 (Crustacea: Decapoda: Caridea) in the western Pacific.

The rare species Plesionka exigua (Rathbun, 1906) is recorded for the first time from three western Pacific localities New Caledonia, Vanuatu and Ryukyu Islands of Japan. Redescription, illustrations on distinguishing characters and color photograph are provided for this poorly known species.

Plesionika sanctaecatalinae Wicksten, 1983 (Crustacea Decapoda Caridea Pandalidae) from off the west coast of Pacific Mexico.

A large series of specimens of Plesionika sanctaecatalinae was obtained during sampling operations off the west coast of the Baja California Peninsula in 2012 and 2014 (TALUD cruises). This material was examined and compared to the original description, the holotype and two paratypes. Although the fresh material fit well with the type material examined, some discrepancies were noted in the illustrations of the original description, particularly regarding scaphocerite and the telson, and new illustrations are provided. The series of sample available from the TALUD cruises allow to increase considerably the number of localities known for this species in the California Current area. A series of unpublished records corresponding to material examined in the original description but not listed in details, allows for further increase of the number of reported localities where P. sanctaecatalinae has been collected. Its vertical distribution in the water column, however, remains unclear due to the fact that no discrete samples are available for this species.

Redescription of the early larval stages of the pandalid shrimp Chlorotocus crassicornis (Decapoda: Caridea: Pandalidae).

The first four larval stages of the pandalid shrimp Chlorotocus crassicornis (A. Costa, 1871) are described and illustrated from laboratory-reared material obtained from ovigerous females collected in the southwestern Spain and south Taiwan. The second to fourth larval stages of this species are reported for the first time to science. Detailed examination of the first larval stages reveals that previous description misidentified some key larval characters which have prevented its identification in plankton samples. It is found that the zoeal morphology of Chlorotocus is not very different from other pandalid larvae, and in fact closely resembles Plesionika and Heterocarpus.

The occurrence of Pandalopsis spinosior Hanamura, Kohno & Sakaji, 2000 (Crustacea: Decapoda: Caridea: Pandalidae) in Hokkaido, northern Japan, and reassessment of its diagnostic characters.

Pandalopsis spinosior Hanamura, Kohno & Sakaji, 2000 (Decapoda: Caridea: Pandalidae) was originally described on the basis of material collected in the Urup Strait, South Kurile Islands, but there have been no subsequent records of the species since the original description. The Marine Science Museum, Fukushima Prefecture (Aquamarine Fukushima) has carried out investigations on deep-water animals in the Nemuro Strait, off Shiretoko Peninsula, Hokkaido, Japan, amongst the collections a large, commercially important pandalid shrimp routinely identified with P. coccinata Urita, 1941. Examination of the specimens from the collections, however, resulted in an unexpected identification with P. spinosior, instead of P. coccinata. In this short article, diagnostic characters of P. spinosior are reassessed, and comparison with P. coccinata is made. The validity of P. zarenkovi Ivanov & Sokolov, 2001, for which possible synonymy with P. spinosior was suggested, is maintained for the time being.

Genetically distinct populations of northern shrimp, Pandalus borealis, in the North Atlantic: adaptation to different temperatures as an isolation factor.

The large-scale population genetic structure of northern shrimp, Pandalus borealis, was investigated over the species' range in the North Atlantic, identifying multiple genetically distinct groups. Genetic divergence among sample localities varied among 10 microsatellite loci (range: FST = -0.0002 to 0.0475) with a highly significant average (FST = 0.0149; P < 0.0001). In contrast, little or no genetic differences were observed among temporal replicates from the same localities (FST = 0.0004; P = 0.33). Spatial genetic patterns were compared to geographic distances, patterns of larval drift obtained through oceanographic modelling, and temperature differences, within a multiple linear regression framework. The best-fit model included all three factors and explained approximately 29% of all spatial genetic divergence. However, geographic distance and larval drift alone had only minor effects (2.5-4.7%) on large-scale genetic differentiation patterns, whereas bottom temperature differences explained most (26%). Larval drift was found to promote genetic homogeneity in parts of the study area with strong currents, but appeared ineffective across large temperature gradients. These findings highlight the breakdown of gene flow in a species with a long pelagic larval phase (up to 3 months) and indicate a role for local adaptation to temperature conditions in promoting evolutionary diversification and speciation in the marine environment.

Species identification of the Northern shrimp (Pandalus borealis) by polymerase chain reaction-restriction fragment length polymorphism and proteomic analysis.

Genomic and proteomic techniques for species identification of meat and seafood products are being widely used. In this study, a genomic approach was used to differentiate Pandalus borealis (the Northern shrimp), which belongs to the superfamily Pandaloidea, from 30 crustaceans consisting of 19 commercially relevant prawns/shrimps species that belong to the superfamily Penaeoidea, which include the families Penaeidae and Solenoceridae, and 11 other crustacean species, including prawns, shrimps, lobsters, and crabs. For this purpose, a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was designed based on the amplification of the 16S rRNA/tRNA(Val)/12S rRNA mitochondrial regions using the primers 16S-CruF and 16S-CruR. The 966-bp PCR products were produced and cleaved with the restriction enzymes AluI, TaqI, and HinfI, which provided species-specific restriction patterns. In addition, a proteomic approach, based on matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) and electrospray ionization-ion trap (ESI-IT) mass spectrometry, was used to identify and characterize new P. borealis-specific peptides that could be useful as potential markers of this species in protein-based detection methods. To our knowledge, this is the first time a molecular method has been successfully applied to identify a wide range of prawn and shrimp species, including P. borealis, for either whole individuals or processed products. However, validation of the methods proposed here is required by applying them to a larger sample of individuals from different populations and geographic origins in order to avoid mainly false-negative results.

Two juvenile hormone esterase-like carboxylesterase cDNAs from a Pandalus shrimp (Pandalopsis japonica): cloning, tissue expression, and effects of eyestalk ablation.

Methyl farnesoate (MF), a crustacean juvenile hormone (JH) analog, plays important roles in the regulation of a number of physiological processes such as molting, metamorphosis, and reproduction. Understanding its metabolic pathway is a key for various potential applications in crustacean aquaculture, including artificial seed production and enhancement of growth. Although the synthetic pathway of MF is well established, little is known about its degradation and recycling in crustaceans. In insects, juvenile hormone esterase (JHE), a carboxylesterase, is responsible for JH inactivation. Two cDNAs, encoding JHE-like carboxylesterases (CXEs) from the hepatopancreas and ovary of Pandalopsis japonica, were isolated by using a combination of in-silico data mining from an expressed sequence tag (EST) database and traditional PCR-based cloning. The full length Pj-CXE1 (2084bp) and Pj-CXE2 (1985bp) cDNAs encoded proteins composed of 584 and 581 amino acids, respectively. The active site sequence and domain organization of the Pj-CXEs were highly conserved, including the catalytic triad and other motifs, which suggested that both Pj-CXEs are biologically active carboxylesterases. Phylogenetic analysis of the deduced sequences of Pj-CXEs showed that both were most closely related to the JHEs from non-lepidopteran insects. End-point RT-PCR showed that Pj-CXE1 was expressed primarily in the gonad, whereas Pj-CXE2 was expressed in both the hepatopancreas and hindgut. Quantitative PCR showed that Pj-CXE1 was upregulated in the gonads by eyestalk ablation (ESA). In contrast, ESA had no significant effect on Pj-CXE2 expression in hepatopancreas or gonad. This is the first report of the cloning of two JHE-like CXE cDNAs in decapods and the upregulation of Pj-CXE1 by acute withdrawal of eyestalk neuropeptides. Further study is needed to understand the function of CXEs in MF metabolism and its regulation by eyestalk neuropeptides.

Crustacean fauna (Stomatopoda: Decapoda) associated with the deepwater fishery of Heterocarpus vicarius (Decapoda: Pandalidae) along the Pacific coast of Costa Rica

Commercial bottom trawlng is a successful and commonly used method to catch marine shrimps. However, the shrimp fishing gears are poorly selective, and in addition to the target species they catch and retain large quantities of non-target species (bycatch). This study presents data concerning species composition and depth distribution of the crustacean fauna (stomatopods and decapods) associated with Heterocarpus vicarius catches from Pacific Costa Rica. A total of 74 samples (three to five 20 min-tows each month) were taken between January 2004 and December 2005 with commercial shrimp trawlers at depths varying between 192 and 350 m. In all depth ranges analyzed, total catch of crustaceans was significantly higher than that of fishes. A total of 28 decapods and two stomatopod species were identified. In comparison to other bycatch composition of comparable fisheries in Latin America, the crustacean fauna of the H. vicarius fishery in Costa Rica is highly diverse. Most common species were Solenocera agassizii (Solenoceridae), Squilla biformis (Squillidae), Plesionika trispinus (Pandalidae), and Pleuroncodes sp. (Galatheidae), reaching total catch percentages of 57.2 %, 81.5 %, 91.8 %, and 99.6 % of individual catches, respectively. The results presented herein may contribute to the development of responsible management strategies for the deepwater fisheries in Costa Rica and Central America.

Las redes de arrastre son un método exitoso y comúnmente utilizado para la pesca de camarones marinos. Sin embargo, son poco selectivas y, junto con las especies comerciales, se pesca también grandes cantidades de otras especies (fauna acompañante). Este estudio presenta información acerca de la composición y distribución batimétrica de los crustáceos (estomatópodos y decápodos) asociados con las capturas de Heterocarpus vicarius en el Pacífico de Costa Rica. Entre enero del 2004 y diciembre de 2005, se tomaron 74 muestras en profundidades de 192-350 m (tres a cinco arrastres de 20 min cada mes), utilizando redes de arrastre comercial dirigidas a la pesca de camarones. En todos los intervalos de profundidad analizados, las capturas (kg) de crustáceos fueron significativamente mayores que las de los peces. Se identificaron 28 especies de decápodos y dos de estomatópodos. Al comparar la composición de especies de fauna acompañante de H. vicarius en Costa Rica con otras pesquerías de camarones en América Latina, se encuentra que la fauna de crustáceos es muy diversa. Las especies más comunes fueron Solenocera agassizii (Solenoceridae), Squilla biformis (Squillidae), Plesionika trispinus (Pandalidae) y Pleuroncodes sp. (Galatheidae),alcanzando porcentajes máximos de concentración - en un sólo arrastre - de hasta 57.2 %, 81.5 %, 91.8 % y 99.6 % de la captura, respectivamente. Los resultados presentados aquí pueden contribuir al desarrollo de estrategias de manejo responsable para las pesquerías de aguas profundas en Costa Rica y en Centroamérica.

Molecular and enzymatic properties of a cathepsin L-like proteinase with distinct substrate specificity from northern shrimp (Pandalus borealis).

We purified a cathepsin L-like proteinase to homogeneity from the hepatopancreas of northern shrimp Pandalus borealis by several chromatographic procedures. The purified proteinase showed the highest specificity for leucine residue at P2, a specificity pattern similar to cathepsins S and K whereas proline and arginine residues were not suitable as P2 substrates. However, unlike these proteinases, it accepted valine almost equally to the phenylalanine residue at P2. The shrimp cathepsin was strongly inhibited by E-64, leupeptin and antipain, while benzyloxycarbonyl-Phe-Tyr(t-Bu)-CHN2, a specific inhibitor of cathepsin L, remained largely ineffective. Next, we determined the primary structure of the shrimp enzyme by molecular cloning and investigated the residues constituting the S2 subsite, which is possibly involved in its unusual substrate specificity. The deduced amino acid sequence of the shrimp proteinase shared the highest identity of 65% with a cathepsin L-like proteinase from lobster, but its identity to the well-characterized mammalian cathepsins S, L, and K fell within narrower ranges of 52-55%. However, the shrimp proteinase differed from these cathepsins in some key residues including, for example, the unique occurrence of cysteine and glutamine residues at the structurally important S2 subsite. Interestingly, transcripts of this proteinase were exclusively detected in the shrimp gut coinciding with its broad pH activity and stability profiles, which is also unusual as a cysteine proteinase. These results suggest that the shrimp enzyme is homologous to mammalian cathepsins S, L, and K, but is distinct from each of these proteinases in both enzymatic and structural properties.