Arctic puzzle: Pioneering a northern shrimp (Pandalus borealis) habitat model in Disko Bay, West Greenland.

Recent advancements in spatial modelling leverage remote sensing data and statistical species-environment relationships to forecast the distribution of a specific species. Our study focuses on Disko Bay in West Greenland, recognized as a significant marine biodiversity hotspot in the region. We conducted comprehensive analyses using multiple datasets spanning from 2010 to 2019, incorporating shrimp and fish surveys, commercial shrimp fishery catches, high-resolution (25 × 25 m) multibeam bathymetry and backscatter data along with a medium-resolution (200 × 200 m) bathymetric model, measured and modelled oceanographic data, and satellite chlorophyll data. Through multivariate regression analysis, we tested the significance of various physical factors (seafloor depth, sediment class, bottom water temperature, bottom water salinity, bottom current velocity, space, and time), biological factors (chlorophyll a, Greenland halibut (Reinhardtius hippoglossoides)), and anthropogenic impact (shrimp fishery; standardized catch per unit effort) on the density of northern shrimp in the area. Our results indicate a significant association between northern shrimp density, seafloor depth, and sediment class, explaining 36 % of the variation in shrimp density. Subsequently, we developed a high-resolution (optimized) spatial linear mixed-effect model to map the distribution of northern shrimp across Disko Bay, representing the first model of its kind developed for an Arctic area. The optimal habitat for northern shrimp is characterized by medium-deep waters (approximately 150-350 m), turbulent conditions, and mixed sediments, predominantly located in the northern and southern regions of Disko Bay. Notably, the northern region hosts a relatively diverse benthic community, with northern shrimp and sponges as the primary contributors of epibenthic biomass. This novel high-resolution model significantly enhances our understanding of the physical drivers and detailed spatial patterns influencing the distribution of northern shrimp in the Arctic.

Spatial and economic quantification of provisioning service by eelgrass beds in Lake Notoro, Hokkaido, Japan.

Eelgrass beds provide a habitat for many high-value fishery resources, and provisioning services, one of the ecosystem services, need to be quantified. However, few examples have been evaluated spatially. We determined the distribution of eelgrass beds in Lake Notoro, a marine lagoon in Hokkaido, Japan, and quantified the provisioning services by the eelgrass beds in relation to Pandalus latirostris, a fishery resource. Acoustic measurement surveys of the eelgrass beds and catch surveys of the shrimp were conducted in July and August 2015. The relationship between catch per unit effort (CPUE) of shrimp and the distribution of eelgrass beds was shown. The estimated distribution area of eelgrass beds was 7.07 km2. Shrimp was frequently caught at water depths of 3-5 m, approximately 200 m from the edge of the eelgrass beds. The expected catch of shrimp in the fishing area of Lake Notoro in 2015 was 25.37 tons and US$ 463.6 thousand. Eelgrass beds were found to affect the fisheries production not only on the inside but also at the edge and outside. The entire coastal space should be evaluated, while considering the effect of the distribution of eelgrass beds, to quantify the provisioning services.

Effects of heatwave events on the seagrass-dwelling crustacean Pandalus latirostris in a subarctic lagoon.

Heatwaves often cause mass mortality of organisms in seagrass areas, and they eventually alter some ecological functions of seagrass ecosystems. In subarctic regions, however, the effects of heatwaves on seagrass areas are still unclear. In a subarctic lagoon of northern Japan, we examined the effects of heatwaves on the Hokkai shrimp, Pandalus latirostris, a commercially exploited species distributed in seagrass areas of northern Japan and eastern Russia. A long-term survey of the surface water temperature in the lagoon clarified a gradual increase in the frequency and intensity of heatwave events since 1999. Surveys of the water temperature at a seagrass area in the lagoon during summer have also demonstrated that the maximum water temperature had been exceeding 25 °C, unusually high for this location, regardless of water depth. These results indicate that the effects of heatwaves in seagrass areas in a subarctic region had become as severe as those in tropical and temperate regions. We also experimentally evaluated the effects of this unusually high water temperature (25 °C) on the survival of P. latirostris by changing the length of exposure time. Some individuals suffered damage to their intestinal mucosal structure after exposure for 12 h or longer, and all individuals died after exposure for 120 h. Our results suggest that heatwaves possibly cause mass mortality in P. latirostris in the following sequence: heat stress, damage to the intestinal epithelial mucosal structure, degradation of nutrient absorption and immunological function of the intestine, energy deficiency and disease infection, and finally mortality. This study, conducted in subarctic closed waters, concludes that it is essential to become familiar with not only trends in heatwaves but also the intermittent occurrence of unusually high water temperature in seagrass areas in order to better understand the process of mortality of organisms that inhabit these ecosystems.

Diacylglycerol acyltransferase (DGAT) in Crangon crangon and Pandalus montagui (Decapoda, Caridea) - Implications for lipid storage capacities and life history traits.

Lipids play essential roles in cell-structuring, cell-signaling, and as efficient metabolic energy stores. Lipid storage capacities determine life history traits of organisms and, thus, their ecological function. Among storage lipids, triacylglycerols (TAGs) are widespread in marine invertebrates. However, abilities to accumulate TAGs can vary even between closely related species, such as the caridean shrimps Crangon crangon and Pandalus montagui. The first species shows low TAG levels throughout the year in the main storage organ, the midgut gland, while the latter accumulates high TAG-levels, peaking in summer. TAGs synthesis is facilitated by the terminal step of the Kennedy-pathway, where the enzyme diacylglycerol-acyltransferase (DGAT) catalyzes the esterification of diacylglycerols with activated fatty acids. We investigated DGAT activity in the midgut gland using a fluorescent enzyme assay. Sequence information was extracted from whole transcriptome shotgun assembly data, that is publicly available on NCBI, and catalytic properties were deduced from molecular structure analysis. C. crangon showed significantly lower TAG synthesis rates than P. montagui, which explains the native TAG levels. Transcriptome data yielded several isoforms of DGAT enzymes in both species. C. crangon DGAT showed point mutations, which are capable of obstructing the catalytic capacity. The consequences are limited starvation resistance and, thus, presumably restricting C. crangon to a habitat with year-round sufficient food. In contrast, higher TAG synthesis rates presumably enable P. montagui to extend into northern subarctic habitats with limited food availability in winter. Moreover, the limited TAG synthesis and accumulation in the midgut gland may force C. crangon to direct energy into the ovaries, which results in multiple spawnings.

Environmental and climate variability drive population size of annual penaeid shrimp in a large lagoonal estuary.

Species with short life spans frequently show a close relationship between population abundance and environmental variation making these organisms potential indicator species of climatic variability. White (Penaeus setiferus), brown (P. aztecus), and pink (P. duorarum) penaeid shrimp typically have an annual life history and are of enormous ecological, cultural, and economic value to the southeastern United States and Gulf of Mexico. Within North Carolina, all three species rely on the Pamlico Sound, a large estuarine system that straddles Cape Hatteras, one of the most significant climate and biogeographic breaks in the world, as a nursery area. These characteristics make penaeid species within the Pamlico Sound a critical species-habitat complex for assessing climate impacts on fisheries. However, a comprehensive analysis of the influence of the environmental conditions that influence penaeid shrimp populations has been lacking in North Carolina. In this study, we used more than 30 years of data from two fishery-independent trawl surveys in the Pamlico Sound to examine the spatial distribution and abundance of adult brown, white, and pink shrimp and the environmental drivers associated with adult shrimp abundance and juvenile brown shrimp recruitment using numerical models. Brown shrimp recruitment models demonstrate that years with higher temperature, salinity, offshore windstress, and North Atlantic Oscillation phase predict increased abundance of juveniles. Additionally, models predicting adult brown, white, and pink shrimp abundance illustrate the importance of winter temperatures, windstress, salinity, the North Atlantic Oscillation index, and the abundance of spawning adult populations from the previous year on shrimp abundance. Our findings show a high degree of variability in shrimp abundance is explained by climate and environmental variation and indicate the importance of understanding these relationships in order to predict the impact of climate variability within ecosystems and develop climate-based adaptive management strategies for marine populations.

Acute and Sublethal Effects of Deltamethrin Discharges from the Aquaculture Industry on Northern Shrimp (Pandalus borealis Krøyer, 1838): Dispersal Modeling and Field Investigations.

Pharmaceutical deltamethrin (Alpha Max), used as delousing treatments in aquaculture, has raised concerns due to possible negative impacts on the marine environment. A novel approach combining different scientific disciplines has addressed this topic. Acute (mortality) and sublethal effects (i.e., fitness, neurological, immunological, and oxidative responses) of exposure of northern shrimp (Pandalus borealis) were studied in laboratory experiments. Passive water sampling combined with sediment analyses revealed environmental concentrations. Finally, dispersal modeling was performed to predict environmental concentrations. Ecotoxicological analyses showed mortality in shrimp after 1 h of exposure to 2 ng L-1 (1000-fold dilution of treatment dose), revealing a high sensitivity to deltamethrin. Sublethal effects included induction of acetylcholinesterase and acyl CoA oxidase activities and oxidative impairment, which may be linked to neurotoxic responses. Field concentrations of 10-200 ng L-1 in water (100 m from the pens) and

Effect of the Nordmøre grid bar spacing on size selectivity, catch efficiency and bycatch of the Barents Sea Northern shrimp fishery.

The introduction of the Nordmøre grid in shrimp trawls has reduced the bycatch of non-target species. In the Norwegian Northern shrimp (Pandalus borealis) fishery, the mandatory selective gear consists of a Nordmøre grid with 19 mm bar spacing combined with a 35 mm mesh size diamond mesh codend. However, fish bycatch in shrimp trawls remains a challenge and further modifications of the gear that can improve selectivity are still sought. Therefore, this study estimated and compared the size selectivity of Nordmøre grids with bar spacings of 17 and 21 mm. Further, the effect of applying these two grids on trawl size selectivity was predicted and compared to the legislated gear configuration. Experimental fishing trials were conducted in the Barents Sea where the bottom trawl fleet targets Northern shrimp. Results were obtained for the target species and two by-catch species: cod (Gadus morhua) and American plaice (Hippoglossoides platessoides). This study demonstrated that reducing bar spacing can significantly reduce fish bycatch while only marginally affecting catch efficiency of Northern shrimp. This is a potentially important finding from a management perspective that could be applicable to other shrimp fisheries where flexibility in the use of different grid bar spacings may be beneficial to maximize the reduction of unwanted bycatch while minimizing the loss of target species.

Reservoirs of Red-Spotted Grouper Nervous Necrosis Virus (RGNNV) in Squid and Shrimp Species of Northern Alboran Sea.

The production of the aquaculture industry has increased to be equal to that of the world fisheries in recent years. However, aquaculture production faces threats such as infectious diseases. Betanodaviruses induce a neurological disease that affects fish species worldwide and is caused by nervous necrosis virus (NNV). NNV has a nude capsid protecting a bipartite RNA genome that consists of molecules RNA1 and RNA2. Four NNV strains distributed worldwide are discriminated according to sequence homology of the capsid protein encoded by RNA2. Since its first description over 30 years ago, the virus has expanded and reassortant strains have appeared. Preventive treatments prioritize the RGNNV (red-spotted grouper nervous necrosis virus) strain that has the highest optimum temperature for replication and the broadest range of susceptible species. There is strong concern about the spreading of NNV in the mariculture industry through contaminated diet. To surveil natural reservoirs of NNV in the western Mediterranean Sea, we collected invertebrate species in 2015 in the Alboran Sea. We report the detection of the RGNNV strain in two species of cephalopod mollusks (Alloteuthis media and Abralia veranyi), and in one decapod crustacean (Plesionika heterocarpus). According to RNA2 sequences obtained from invertebrate species and reported to date in the Mediterranean Sea, the strain RGNNV is predominant in this semienclosed sea. Neither an ecosystem- nor host-driven distribution of RGNNV were observed in the Mediterranean basin.

DNA metabarcoding reveals the importance of gelatinous zooplankton in the diet of Pandalus borealis, a keystone species in the Arctic.

Information about the dietary composition of a species is crucial to understanding their position and role in the food web. Increasingly, molecular approaches such as DNA metabarcoding are used in studying trophic relationships, not least because they may alleviate problems such as low taxonomic resolution or underestimation of digestible taxa in the diet. Here, we used DNA metabarcoding with universal primers for cytochrome c oxidase I (COI) to study the diet composition of the northern shrimp (Pandalus borealis), an Arctic keystone species with large socio-economic importance. Across locations, jellyfish and chaetognaths were the most important components in the diet of P. borealis, jointly accounting for 40%-60% of the total read abundance. This dietary importance of gelatinous zooplankton contrasts sharply with published results based on stomach content analysis. At the same time, diet composition differed between fjord and shelf locations, pointing to different food webs supporting P. borealis in these two systems. Our study underlines the potential of molecular approaches to provide new insights into the diet of marine invertebrates that are difficult to obtain with traditional methods, and calls for a revision of the role of gelatinous zooplankton in the diet of the key Arctic species P. borealis, and in extension, Arctic food webs.

Evaluation of probiotic characteristics and whole genome analysis of Pediococcus pentosaceus MR001 for use as probiotic bacteria in shrimp aquaculture.

The development of non-antibiotic and environmentally friendly agents is a key consideration for health management in shrimp aquaculture. In this study, the probiotic potential in shrimp aquaculture of Pediococcus pentosaceus MR001, isolated from Macrobrachium rosenbergii, was investigated by means of feeding trial and genetic characterization. In the feeding trial, dietary supplementation with P. pentosaceus MR001 significantly increased weight gain and digestive enzyme activity (p < 0.05) in shrimp, Litopenaeus vannamei. The intestinal histology showed that shrimp given the probiotic diet had healthier guts than the control group. Also, the immune gene expression and the survival rate in the treatment group were significantly increased when compared with the control group. The genetic characteristics of P. pentosaceus strain MR001 were explored by performing whole-genome sequencing (WGS) using the HiSeq 2500 platform and PacBio system, revealing the complete circular genome of 1,804,896 bp. We also identified 1789 coding genes and subsequently characterized genes related to the biosynthesis of bacteriocins, stress resistance, and bile tolerance. Our findings suggest that insights in the functional and genetic characteristics of P. pentosaceus strain MR001 could provide opportunities for applications of such strain in shrimp diet supplementation.

Effects of simulated environmental discharges of the salmon lice pesticides deltamethrin and azamethiphos on the swimming behaviour and survival of adult Northern shrimp (Pandalus borealis).

Swimming behaviour was investigated in adult egg-carrying northern shrimp (Pandalus borealis) exposed to dilute concentrations of the pesticides Alpha Max® (active ingredient deltamethrin) and Salmosan® (active ingredient azamethiphos) used to control parasitic copepods in salmon aquaculture. These treatments are applied topically within fish nets or well boats. Following a short treatment period, the pesticides are directly discharged to sea, exposing non-target organisms such as P. borealis to diluted concentrations of these chemicals. Locomotor activity was measured continuously in individual shrimp over several days within which they were exposed to treatments of diluted AlphaMax® or Salmosan®. Dilutions were based on modelling and dispersion studies from the literature and were considered environmentally realistic for greater than 1 km from point of discharge. 24 h continuous flow treatments were delivered within a 3.5-day monitoring period to observe the timeline of events following the release of treatment water, addressing questions of temporal responses in locomotor activity, recognising key time points of significant events and assessing the survival capacity of the shrimp. Exposure of shrimp to 1 ng l-1 deltamethrin triggered an immediate increase in swimming activity which reduced in intensity over the following 22 h leaving all shrimp either moribund or dead. A further exposure trial exposing shrimp to 0.2 ng l-1 deltamethrin (nominal) showed an increase in activity at the start of exposure that continued throughout the 24 h delivery, returning to previous levels by the end of the 3.5-day monitoring period. All these shrimps survived for at least four weeks after exposure, putting the threshold concentration of deltamethrin leading to immobility or death in adult P. borealis within this study at greater than 0.2 ng l-1 (nominal) and less than 1 ng l - 1 (measured). Exposure of P. borealis to azamethiphos at 30 ng l-1 induced several periods of significantly increased activity within the first 10 h of exposure and an extended period of reduced activity during post exposure, though no morbidity was observed with this treatment. No significant increase in activity or morbidity was observed in shrimp during a water vehicle control assessment. Shrimps exposed to a combination of 30 ng l-1 azamethiphos and 1 ng l-1 deltamethrin broadly followed the response pattern shown by shrimp exposed to 1 ng l-1 deltamethrin alone. Pesticide residues were not detected in post exposure tissue analyses for either chemical. The potential ecological significance of increased swimming activity at the start of pesticide exposures is discussed.

Northern shrimp Pandalus borealis population collapse linked to climate-driven shifts in predator distribution.

The northern shrimp (Pandalus borealis Krøyer) population in the Gulf of Maine collapsed during an extreme heatwave that occurred across the Northwest Atlantic Ocean in 2012. Northern shrimp is a boreal species, and reaches its southern limit in the Gulf of Maine. Here we investigate proximate causes for the population collapse using data from fishery-independent surveys, environmental monitoring, and the commercial fishery. We first examined spatial data to confirm that the decline in population estimates was not due to a major displacement of the population, and then tested hypotheses related to fishing mortality and shifts in predation pressure. Fishing mortality may have contributed but could not explain the magnitude of the decline or the disappearance of pre-exploitable size individuals. Stomach contents analysis and biomass trends revealed no new fish predators of shrimp. However, longfin squid (Doryteuthis pealeii Lesueur) was unique among all species in showing time-series biomass peaks during spring, summer and fall of 2012, and spatial overlap with northern shrimp was unusually high in 2012. Longfin squid is a voracious and opportunistic predator that consumes crustaceans as well as fish. We hypothesize that the warmer temperatures of 2012 not only led to expansion of longfin squid distribution in Gulf of Maine, but had differential effects on migration phenology that further increased spatial overlap with northern shrimp. The weight of our evidence suggests that longfin squid predation was likely a significant factor in the collapse of northern shrimp in the Gulf of Maine.

Effects of crude oil and field-generated burned oil residue on Northern shrimp (Pandalus borealis) larvae.

In situ burning (ISB) is an oil spill clean-up option used by oil spill responders to mitigate impacts on the marine environment. Despite advantages such as high efficiency and potential applicability for challenging areas such as the Arctic, the actual environmental side effects are still uncertain. Acute and sublethal effects of the water accommodated fractions (WAFs from 25 g oil/L seawater) of a pre-weathered North Sea crude (Oseberg Blend 200 °C+) and field generated ISB residue were evaluated on Northern shrimp (Pandalus borealis) larvae. The larvae were first exposed for 96 h to a serial dilution of seven concentrations, and then maintained for two weeks in clean seawater post-exposure. No acute (mortality) or sublethal effects (feeding, development, or growth) were detected in any of the ISB residue concentrations. Significant larvae mortality was found in the three highest concentrations of crude oil (96-h LC50:469 µg/L total petroleum hydrocarbon) but no sublethal effects were found in the surviving larvae post-exposure. This study indicates that applying ISB could mitigate acute impacts of spilled oil on shrimp larvae.

Misidentification and notes on Plesionika semilaevis, Spence Bate, 1888 (Crustacean: Decapoda: Caridea) from the southern coast of India.

The commercial deep-sea caridean shrimp Plesionika martia (Milne-Edwards 1883) has long been recorded from India and constitutes an important species of deep-sea shrimp catches in the southern coast of India. However, the present study revealed that all the previous records of "Plesionika martia" is actually a misidentification of the closely related species P. semilaevis, which was recently obtained from Indian waters. The specimens were collected from three fish landing harbours (Sakthikulangara, Kalamuku, and Tuticorin) fished from the depth of about 150-250 m along the southern coast of India during 2014 to 2017. The level of interspecies genetic divergence between 16S rDNA (16.8-18.6%) and COI (26.1%) sequences of the Indian P. semilaevis and P. martia sequence retrieved from NCBI were found to be comparatively high. The current work illustrates the detailed morphological characters with color photographs of the species, P. semilaevis off the Indian Exclusive Economic Zone (EEZ).

Chitin isolation from crustacean waste using a hybrid demineralization/DBD plasma process.

Conventional isolation of chitin from crustacean waste demands the use of high amounts of hazardous chemicals, hence not leading to a sustainable process. Atmospheric-pressure dielectric barrier discharge (DBD) plasma has demonstrated an enhanced ability to remove proteins directly from the biomass without the formation of any waste. Simultaneously, organic acids have proven very efficient in the removal of inorganic minerals from crustacean waste. Therefore, a hybrid process composed of DBD plasma and demineralization using organic acids has been successfully applied for the isolation of chitin. Results showed that the integration of nitrogen-based plasma and lactic acid demineralization allowed the elimination of 90 % of the proteins and ensures the complete removal of minerals from shrimp shells waste. The isolated chitin was further characterized using distinct techniques, namely XPS, ATR-FTIR, XRD and SEM. Chitin degree of deacetylation and molecular weight were also assessed. Hence, this work presents a sustainable and feasible platform for the extraction and purification of chitin from crustacean waste with almost zero waste formed.

Possible climate-induced environmental impacts on parasite-infection rates of northern shrimp Pandalus borealis eggs in the Gulf of Maine.

The Gulf of Maine northern shrimp Pandalus borealis population once supported a significant commercial winter fishery for the New England states. However, the fishery has been on moratorium since 2014 due to consecutive recruitment failures. The issue of parasite-infected eggs, so-called 'white eggs,' has long been identified for the Gulf of Maine northern shrimp, which makes shrimp eggs nonviable and subsequently hampers the recruitment potential. Furthermore, the proportion of infected females was observed to increase with water temperature. As Gulf of Maine temperatures have been increasing for decades, it is important to re-visit issues related to white eggs to evaluate possible impacts of climate-induced environmental changes on the white egg infection rates. We used biological samples collected by the Northeast Fisheries Science Center in 2012-2016 to evaluate the probability that a female shrimp was infected (Pinf) and the proportion of white eggs in an infected female shrimp (pwe). Although Pinf was high, with an average of 73.81% over the Gulf of Maine, pwe was mostly <5%. The variation in both Pinf and pwe examined in this study was not well explained by environmental factors or female body size. However, the average rates of both Pinf and pwe observed in this study were higher than those observed in the 1960s when the bottom temperatures were cooler. The results can be used to account for egg mortality and provide information on potential impacts of possible climate-induced variability on shrimp population dynamics.

Effects of the sea lice bath treatment pharmaceuticals hydrogen peroxide, azamethiphos and deltamethrin on egg-carrying shrimp (Pandalus borealis).

This study investigated effects of sea lice pharmaceuticals on egg-bearing deep-water shrimp (Pandalus borealis). Both mortality and sub-lethal effects (behavior, embryo development, and reproductive output) were studied for each of three pharmaceuticals alone and in different sequential combinations. The most severe effect was observed for deltamethrin where 2 h exposure to 330 times diluted treatment dose (alone and in sequential application with hydrogen peroxide and azamethiphos) induced almost 100% mortality within a few days after exposure. Similar effects were not observed for hydrogen peroxide or azamethiphos. However, sequential treatment of hydrogen peroxide and azamethiphos (2 h exposure to each pharmaceutical; 500 times dilution) resulted in >40% mortality during the first week following treatment. No sub-lethal effects or loss of eggs in female shrimp could be related to exposure to the bath treatments. Future studies should investigate potential sub-lethal effects at exposure concentrations close to the no-effect concentration.

The sensitivity of the deepsea species northern shrimp (Pandalus borealis) and the cold-water coral (Lophelia pertusa) to oil-associated aromatic compounds, dispersant, and Alaskan North Slope crude oil.

This study investigated the sensitivity of two deepsea species using mortality of northern shrimp (Pandalus borealis) and polyp activity of stony coral (Lophelia pertusa) to dispersant, Corexit 9500 and aromatic hydrocarbons (toluene, 2-methylnaphthalene, phenanthrene) in 96-h tests. Resulting hydrocarbon toxicity data were fit to the Target Lipid Model to generate predictive models and determine species sensitivity. Toxicity of chemically enhanced water accommodated fractions of Alaskan North Slope crude oil (ANS-oil) was also investigated with shrimp using nominal loading, total petroleum hydrocarbons and biomimetic extraction (BE) as oil exposure metrics. Coral were more sensitive to dispersant than shrimp while similar sensitivity was observed for hydrocarbons. Study and literature findings indicate deepsea species exhibit acute sensitivities to dispersant, hydrocarbons and oil that are comparable to pelagic species. Results support use of passive sampling methods to quantify dissolved oil for interpreting oil toxicity tests and suggest models for predicting time-dependence of toxicity warrant re-evaluation.

On the "Plesionika martia" (A. Milne-Edwards, 1883) species group in Indian waters.

Material of the "Plesionika martia" (A. Milne-Edwards, 1883) species group from India had been reported as either P. martia or P. semilaevis Bate, 1888. Recent collection, however, revealed that both P .martia and P. semilaevis occur in Indian waters. COI barcoding gene sequence comparisons of the Indian and topotypic material of the four known species of the "P. martia" group showed that the Andaman Sea specimen is most similar to the topotypic specimens of P. martia even though there is high genetic divergence between them. For P. semilaevis, large sequence divergence is found in the topotypic material from the Philippines while the Indian specimens are genetically similar to one of the topotypic specimens. The characteristics of the Indian material of both species are described and illustrated.

Effects of exposing shrimp larvae (Pandalus borealis) to aquaculture pesticides at field relevant concentrations, with and without food limitation.

Anti-parasitic drugs used in the aquaculture industry are discharged to the sea after treatment of salmon. In this study, the effects of azamethiphos (AZA) in the Salmosan® formulation and deltamethrin (DEL) in the Alpha Max® formulation, have been assessed in Northern shrimp larvae (Pandalus borealis) when administered both separately and in combination. The exposure concentrations were 100 ng/L for AZA and 2 ng/L for DEL, each representing a 1000-fold dilution of the prescribed concentrations for salmon. These two chemicals were combined at these concentrations to give a third treatment (AZA + DEL). When larvae were exposed for two hours on the first, second and third days post hatch (dph), significantly increased mortality and reduced swimming activity were observed for larvae from the DEL and combined AZA + DEL treatments 4 dph, though not in larvae from the AZA treatment. A single pulse exposure, delivered on the first day post hatch, caused similar effects on mortality and swimming activity 4 dph as the three-pulse exposure. Mortality was driven by the presence of DEL in both experiments, with no amplification or reduction of effects observed when DEL and AZA were combined. Larvae were observed for 13 days following the single pulse exposure, with food limitation introduced as an additional stressor on day 4. In the DEL and AZA + DEL treatments mortality continued to increase regardless of food level, with no larvae completing development to stage II. The overriding toxicity of DEL masked any potential effects the reduced food ration may have exerted. Swimming activity was lower for AZA treated larvae than Control larvae 13 dph, when both groups were fed daily, though no other significant changes to mortality, development to stage II, feeding rate or gene expression were observed. Food limited Control and AZA larvae had lower swimming activity and feeding rate than daily fed Control larvae, with expression of pyruvate kinase and myosin genes also downregulated. However, there was no negative effect on survival or successful development to stage II in these treatments. In addition, mesencephalic astrocyte-derived neurotropic factor was downregulated in food limited Control larvae when compared with the daily fed Controls. Results from this study together with reported estimates of dispersion plume concentrations of discharged pesticides indicate that toxic concentrations of deltamethrin could reach shrimp larvae several kilometers from a treated salmon farm.