Recorded captures of American lobster (Homarus Americanus) in Swedish waters and an observation of predation on the European lobster (Homarus Gammarus)

publishedVersio

Taxonomic and genetic confirmed findings of snow crab (Chionoecetes opilio) larvae in the Barents Sea

The snow crab (Chionoecetes opilio) is an Arctic cold-water species native to the northwestern Atlantic Ocean and the northern Pacific Ocean. During the recent decades, a population has established in the Barents Sea. Several aspects of the snow crabs’ biology in this area have not been described, including time of hatching, intermoult duration of the different larval stages and larval distribution. Insight into the early-life stages might increase the understanding of the population's dynamics and further spreading in the Barents Sea as well as inform basis for making monitoring and management decisions. The present study investigated the presence and developmental stage of snow crab larva in plankton samples obtained in the central Barents Sea during a research survey in June and July 2019. Presence of snow crab larvae was confirmed through taxonomic and genetic identification. All larvae were identified as zoea I, which gives an indication of the timing of the hatching period. Morphological measurements coincide well with those reported in studies from the species native distribution range. No larvae of native Hyas spp. were found and overlap in temporal and spatial distribution is discussed. The study provides important information for development of further research into the biology of the snow crab in the Barents Sea.publishedVersio

Modelling chemical releases from fish farms: impact zones, dissolution time, and exposure probability

Tarpaulin bath treatments are used in open net-pen finfish aquaculture to combat parasitic infections, in particular sea lice. After treatment, the toxic wastewater is released directly into the ocean, potentially harming non-target species in the vicinity. We model the dispersion of wastewater chemicals using a high-resolution numerical ocean model. The results are used to estimate the impact area, impact range, dissolution time, and exposure probability for chemicals of arbitrary toxicity. The study area is a fish-farming intensive region on the Norwegian western coast. Simulations are performed at 61 different release dates, each on 16 locations. In our base case where the chemical is toxic at 1% of the treatment concentration, the release of a 16000 m³ wastewater plume traverses a median distance of 1.9 km before being completely dissolved. The median impacted area is 0.9 km² and the median dissolution time is 6.8 hours. These figures increase to 5.9 km, 7.0 km², and 21 hours, respectively, if the chemical is toxic at 0.1 % of the treatment concentration. Locations within fjords have slower dissolution rates and larger impact zones compared to exposed locations off the coast, especially during summer.publishedVersio

Deformities in larvae and juvenile European lobster (Homarus gammarus) exposed to lower pH at two different temperatures

The ongoing warming and acidification of the world's oceans are expected to influence the marine ecosystems, including benthic marine resources. Ocean acidification may especially have an impact on calcifying organisms, and the European lobster (Homarus gammarus) is among those species at risk. A project was initiated in 2011 aiming to investigate long-term effects of ocean acidification on the early life-cycle of lobster under two temperatures. Larvae were exposed to pCO2 levels of ambient water (water intake at 90 m depth), medium 750 (pH = 7.79) and high 1200 μatm pCO2 (pH = 7.62) at temperatures 10 and 18 °C. The water parameters in ambient water did not stay stable and were very low towards the end of the experiment in the larval phase at 10 °C,with pH between 7.83 and 7.90. At 18°, pH in ambient treatment was even lower, between 7.76 and 7.83, i.e. close to medium pCO2 treatment. Long-term exposure lasted 5 months. At 18 °C the development from stage 1 to 4 lasted 14 to 16 days, as predicted under optimal water conditions. Growth was very slow at 10 °C and resulted in three larvae reaching stage 4 in high pCO2 treatment only. There were no clear effects of pCO2 treatment, on either carapace length or dry weight. However, deformities were observed in both larvae and juveniles. The proportion of larvae with deformities increased with increasing pCO2 exposure, independent of temperature. In the medium treatment about 23% were deformed, and in the high treatment about 43% were deformed. None of the larvae exposed to water of pH >7.9 developed deformities. Curled carapace was the most common deformity found in larvae raised in medium pCO2 treatment, irrespective of temperature, but damages in the tail fan occurred in addition to a bent rostrum. Curled carapace was the only deformity found in high pCO2 treatment at both temperatures. Occurrence of deformities after five months of exposure was 33 and 44% in juveniles raised in ambient and low pCO2 levels, respectively, and 21% in juveniles exposed to high pCO2. Deformed claws were most often found in ambient and medium treatment (56%, followed by stiff/twisted walking legs (39%) and puffy carapace (39%). In comparison, at high pCO2 levels 71% of the deformed juveniles had developed a puffy carapace. Overall, about half of the deformed juveniles from the ambient and medium pCO2 treatment displayed two or three different abnormalities; 70% had multiple deformities in the high pCO2 treatment. Some of the deformities in the juveniles may affect respiration (carapace), the ability to find food, or sexual partners (walking legs, claw and antenna), and ability to swim (tail-fan damages)

Modelled dispersal of snow crab (Chionoecetes opilio) larvae and potential settlement areas in the western Barents Sea

Since the mid-1990s, a snow crab (Chionoecetes opilio) population has established in the eastern Barents Sea. Spawning females and newly hatched larvae are now also found in the central Barents Sea, warranting speculations on a further westward colonization by pelagic larvae. Here, we model the potential for larval dispersal and settlement into uncolonized areas in the western Barents Sea. We used a biophysical model of ocean currents and hydrography, coupled with a Lagrangian dispersal algorithm and larval survival functions as response to temperature. The model predicts limited dispersal from the central Barents Sea to western areas, primarily due to a mismatch between prevailing temperature regimes and temperature tolerances for the different larval stages. In addition, there was limited westward transport of water masses with temperatures that would allow completion of the pelagic larval development. We speculate that for larvae to successfully supply benthic recruits to the remaining uncolonized areas in the western Barents Sea, adult crabs would first need to establish new spawning aggregations, for example along the western slopes of the Barents Sea shelf. Immediate implications are limited potential for expanding the fishery to the western areas of the Barents Sea.publishedVersio

Havbeite med hummer: Artsrapport

Program for Utvikling og Stimulering av Havbeite (PUSH)Program for Utvikling og Stimulering av Havbeite (PUSH) startet opp høsten 1990, og programfinansiert feltaktivitet ble avsluttet i 1997. Denne rapporten presenterer hummeraktivitetene i programmet. Ansvarlig for denne rapport er styringsgruppe for hummerforsøkene på Kvitsøy. Styringsgruppen har bestått av Fiskerisjefen i Rogaland som leder og med representanter fra Fiskeridirektoratet, Havforskningsinstituttet, Kvitsøy kommune og fiskarlaget.publishedVersio

The impact of anti-sea lice pesticides, azamethiphos and deltamethrin, on European lobster (Homarus gammarus) larvae in the Norwegian marine environment

Anti-sea lice pesticides, used in the salmonid aquaculture industry, are a growing environmental concern due to their potential to adversely affect non-target crustaceans. Azamethiphos and deltamethrin are two bath treatment pesticides used on salmon farms in Norway, however, limited information is available on their impact on European lobster (Homarus gammarus) larvae in the Norwegian marine environment. Here, we firstly report the lethal (LC50) and effective (EC50) concentrations of azamethiphos and deltamethrin for stage I and stage II larvae, following 1-h exposures. Using a hydrodynamic model, we also modelled the dispersal of both compounds into the marine environment around selected Norwegian farms and mapped the potential impact zones (areas that experience LC50 and EC50 concentrations) around each farm. Our data shows that azamethiphos and deltamethrin are acutely toxic to both larval stages, with LC50 and EC50 values below the recommended treatment concentrations. We also show that the azamethiphos impact zones around farms were relatively small (mean area of 0.04–0.2 km2), however deltamethrin impact zones covered much larger areas (mean area of 21.1–39.0 km2). These findings suggest that deltamethrin poses a significant risk to European lobster in the Norwegian marine environment while the impact of azamethiphos may be less severe.publishedVersio

グンキモノガタリ ニオケル オンリョウ

担当教員: 久保勇(人文社会科学研究科)平成21年度(2009)教養コア科目授業C(芸術と文化)授業コード:G14C1510

Mortality in the rockpool shrimp Palaemon elegans following long-term exposure to low doses of the anti-parasitic drug Teflubenzuron

Anti-parasitic drugs used to control sea lice infestations in the salmonid aquaculture industry are a growing environmental concern due to their potential impacts on non-target crustacean species. This study examined the lethal effects of teflubenzuron, a common in-feed pharmaceutical drug used on Norwegian salmon farms, on a non-target species, rockpool shrimp Palaemon elegans, following an extended exposure period. The standard daily dose for treating salmon is 10 µg teflubenzuron g-1 fish. Adult shrimp were fed 1 of 6 low doses of teflubenzuron (0, 0.0025, 0.005, 0.05, 0.094, 0.188 and 1.88 µg g-1) twice a week for a period of 66 d. Cumulative mortality reached 15, 27, 82 and 100% amongst shrimp exposed to the highest treatment groups (0.05, 0.094, 0.188 and 1.88 µg g-1, respectively). Cumulative mortality amongst shrimp exposed to the 2 lowest teflubenzuron doses and control feed was low (5%). Dose response curves based on measured concentrations within the shrimp were used to calculate a series of lethal threshold concentrations (LCx). The LC5, LC50 and LC90 concentrations of teflubenzuron causing low, median and high levels of mortality in rockpool shrimp were estimated to be 1.2, 18.4 and 150.6 ng g-1, respectively. These concentrations are similar to those reported in wild crustacean species, including shrimp species in the vicinity of Norwegian fish farms, both during and after teflubenzuron medication, suggesting that exposure to low doses of this compound can pose a significant risk to wild shrimp populations.publishedVersio