Catch my drift? Between-farm dispersal of biofouling waste from salmon pen net cleaning: Potential risks for fish health.

Biofouling is a serious challenge for global salmon aquaculture and farmers have to regularly clean pen nets to avoid impacts on stock health and farms' structural integrity. The removed material is released into the surrounding environment. This includes cnidarian species such as hydroids, whose nematocyst-bearing fragments can impact gill health and fish welfare. There is also increasing evidence of the association of parasites and pathogens with biofouling organisms and cleaning fragments. It is unknown whether and how far local current regimes disperse biofouling material and whether this material reaches and interacts with adjacent pens or even neighbouring farms downstream, or wild fish populations in surrounding environments. We focussed on the cnidarian hydroid Ectopleura larynx, one of the most abundant biofouling species on Norwegian aquaculture installations. Using a 3D hydrodynamic model parameterised with physical and biological properties of hydroid particles (derived via field and laboratory studies), we simulated the dispersal of net cleaning waste from two Norwegian salmon farms. Our results demonstrate that net cleaning waste is extensively dispersed throughout neighbouring pens, and even to adjacent aquaculture facilities. Salmon were exposed to concentrations of biofouling particles up to 41-fold elevated compared to background concentrations, and for up to 30.5 h. Maximum dispersal distance of hydroid particles was 5.5 km from the point of release, achieved largely within 48 h. Least-cost distance calculations show that this distance exceeds the nearest-neighbour distance of 70 % of Norway's salmon farms (654 farms). Our study provides some evidence that actions taken to manage biofouling at salmon farms may affect neighbouring farms and surrounding natural environments. The results highlight the potential risks associated with net cleaning: the dispersal of harmful cnidarian particles, associated pathogens, and non-indigenous species, thus underlining the need for novel farming or net cleaning technologies that prevent the release of potentially harmful cleaning waste.

Effects of petrogenic pollutants on North Atlantic and Arctic Calanus copepods: From molecular mechanisms to population impacts.

Oil and gas industries in the Northern Atlantic Ocean have gradually moved closer to the Arctic areas, a process expected to be further facilitated by sea ice withdrawal caused by global warming. Copepods of the genus Calanus hold a key position in these cold-water food webs, providing an important energetic link between primary production and higher trophic levels. Due to their ecological importance, there is a concern about how accidental oil spills and produced water discharges may impact cold-water copepods. In this review, we summarize the current knowledge of the toxicity of petroleum on North Atlantic and Arctic Calanus copepods. We also review how recent development of high-quality transcriptomes from RNA-sequencing of copepods have identified genes regulating key biological processes, like molting, diapause and reproduction in Calanus copepods, to suggest linkages between exposure, molecular mechanisms and effects on higher levels of biological organization. We found that the available ecotoxicity threshold data for these copepods provide valuable information about their sensitivity to acute petrogenic exposures; however, there is still insufficient knowledge regarding underlying mechanisms of toxicity and the potential for long-term implications of relevance for copepod ecology and phenology. Copepod transcriptomics has expanded our understanding of how key biological processes are regulated in cold-water copepods. These advances can improve our understanding of how pollutants affect biological processes, and thus provide the basis for new knowledge frameworks spanning the effect continuum from molecular initiating events to adverse effects of regulatory relevance. Such efforts, guided by concepts such as adverse outcome pathways (AOPs), enable standardized and transparent characterization and evaluation of knowledge and identifies research gaps and priorities. This review suggests enhancing mechanistic understanding of exposure-effect relationships to better understand and link biomarker responses to adverse effects to improve risk assessments assessing ecological effects of pollutant mixtures, like crude oil, in Arctic areas.

An annual profile of the impacts of simulated oil spills on the Northeast Arctic cod and haddock fisheries.

We simulate the combined natural and pollutant-induced survival of early life stages of NEA cod and haddock, and the impact on the adult populations in response to the time of a major oil spill in a single year. Our simulations reveal how dynamic ocean processes, controlling both oil transport and fate and the frequency of interactions of oil with drifting fish eggs and larvae, mediate the magnitude of population losses due to an oil spill. The largest impacts on fish early life stages occurred for spills initiated in Feb-Mar, concomitant with the initial rise in marine productivity and the earliest phase of the spawning season. The reproductive health of the adult fish populations was maintained in all scenarios. The study demonstrates the application of a simulation system that provides managers with information for the planning of development activities and for the protection of fisheries resources from potential impacts.

Simulating crude oil exposure, uptake and effects in North Atlantic Calanus finmarchicus populations.

A simulation model framework (SYMBIOSES) that includes a 3-dimensional ocean physics and biology model and a model for transport and fate of oil was used to investigate the potential for bioaccumulation and lethal/sublethal effects of oil components in the copepod Calanus finmarchicus in the Lofoten-Vesterålen archipelago of Norway. The oil model is coupled with the biology model by way of a bioaccumulation model, from which mortality and reduction in reproduction are calculated via a total body burden (TBB). The simulation results indicate that copepod body burden levels are affected by the spill type (surface spill, subsea blowout) and the spill timing (spring, autumn). The effects of oil component bioaccumulation on the copepod population for all scenarios are small, though greatest in the subsea blowout scenarios. We attribute this to the limited spatial and temporal overlap between copepods and oil in the environment simulated by the model. The coupling of the processes of oil transport, bioaccumulation/excretion and the associated effects are discussed in the context of the model framework and with a view towards applications for Ecological Risk Assessment (ERA).

Multiscale modelling of cage effects on the transport of effluents from open aquaculture systems.

Most Atlantic salmon mariculture operations use open sea cages for the grow out phase. The ultimate fate and effects of the effluents and the possibilities of disease transfer between fish farms are major concerns for farmers, governance and the general public alike. Numerical model systems applied to studying and managing effluents and disease transfer in mariculture must realistically resolve the hydrodynamics in the vicinity of the fish farms. In the present study, the effects of the aquaculture structures on the current patterns were introduced in the ocean model system SINMOD. The drag parameters for the ocean model were determined by comparing the simulation results from the ANSYS Fluent ® software suite and SINMOD in an idealized channel setting with uniform currents. The model was run for a number of realistic scenarios in high horizontal resolution (∼30 m) with sea cages influencing the flow field. Comparisons between extensive current measurements and the simulation results showed that the model system reproduced the current local current field well. By running simulation scenarios with and without the effects of the sea cages on the flow field, it was possible to assess the importance of such effects for numerical dispersal models and aquaculture environment interactions simulations and hence for assessment of environmental impacts.

Assessing impacts of simulated oil spills on the Northeast Arctic cod fishery.

We simulate oil spills of 1500 and 4500m3/day lasting 14, 45, and 90days in the spawning grounds of the commercial fish species, Northeast Arctic cod. Modeling the life history of individual fish eggs and larvae, we predict deviations from the historical pattern of recruitment to the adult population due to toxic oil exposures. Reductions in survival for pelagic stages of cod were 0-10%, up to a maximum of 43%. These reductions resulted in a decrease in adult cod biomass of <3% for most scenarios, up to a maximum of 12%. In all simulations, the adult population remained at full reproductive potential with a sufficient number of juveniles surviving to replenish the population. The diverse age distribution helps protect the adult cod population from reductions in a single year's recruitment after a major oil spill. These results provide insights to assist in managing oil spill impacts on fisheries.

Crude oil affecting the biomass of the marine copepod Calanus finmarchicus: Comparing a simple and complex population model.

In the current study differences were evaluated between a complex 3D multistage population model (SINMOD) and a simpler consumer-resource population model for estimating the effects of crude oil on the marine copepod Calanus finmarchicus. The SINTEF OSCAR model was used to simulate hypothetical oil spills in the Lofoten area in 1995, 1997, and 2001. Both population models simulated a negligible effect of crude oil on the Calanus' biomass when assuming low species sensitivity. The simple model estimated a larger effect on the biomass (up to a 100% decline) compared to the complex model (maximum decline of 60-80%) at high species sensitivity to crude oil. These differences may be related to the inclusion of copepod advection in the complex model. Our study showed that if little data is available to parameterize a model, or if computational resources are scarce, the simple model could be used for risk screening. Nevertheless, the possibility of including a dilution factor for time-varying biomass should be examined to improve the estimations of the simple model. The complex model should be used for a more in depth risk analysis, as it includes physical processes such as the drift of organisms and differentiation between developmental stages.

The role of environmental biotechnology in exploring, exploiting, monitoring, preserving, protecting and decontaminating the marine environment.

In light of the Marine Strategy Framework Directive (MSFD) and the EU Thematic Strategy on the Sustainable Use of Natural Resources, environmental biotechnology could make significant contributions in the exploitation of marine resources and addressing key marine environmental problems. In this paper 14 propositions are presented focusing on (i) the contamination of the marine environment, and more particularly how to optimize the use of biotechnology-related tools and strategies for predicting and monitoring contamination and developing mitigation measures; (ii) the exploitation of the marine biological and genetic resources to progress with the sustainable, eco-compatible use of the maritime space (issues are very diversified and include, for example, waste treatment and recycling, anti-biofouling agents; bio-plastics); (iii) environmental/marine biotechnology as a driver for a sustainable economic growth.

Modelling produced water dispersion and its direct toxic effects on the production and biomass of the marine copepod Calanus finmarchicus.

Zooplankton is a key group in North Atlantic and Arctic food chains, and assessment and minimization of adverse effects from petroleum activities to this resource are important. The potential direct effects of produced water discharges on the biomass of Calanus finmarchicus were evaluated using a fully coupled, high resolution 3D hydrodynamic-ecological model system (SINMOD). Several scenarios with varying effects of produced water concentrations were considered. In order to reduce numerical dilution of the produced water effluents, a "sub grid" model component of higher resolution (80 m horizontal resolution vs 800 m for the main model grid) was developed and implemented. The results show that dilution and dispersion of produced water varies between locations. In general, realistically simulated concentrations of produced water were too low to have significant effects on the C. finmarchicus biomass and reproduction according to the toxicity-dilution profiles used, even when the toxicity of the produced water was increased 10-fold. The decrease in C. finmarchicus biomass was partially compensated by a slight increase in production.

Apparent hyperalgesia after lesions of the descending serotonergic pathways is due to increased tail skin temperature.

It has been suggested that the descending serotonergic pathways exercise a tonic inhibition on nociception in the spinal cord. In this study 5,6-dihydroxytryptamine (5,6-DHT, 20 micrograms base) injected intrathecally in rats reduced spinal serotonin concentration to 3.5% of control levels without significantly affecting spinal noradrenaline. The lesion reduced the mean tail-flick latency by approximately 35% and increased the mean tail skin temperature by approximately 3.5 degrees C; both parameters gradually returned to normal values within 2-3 weeks. Both in controls and in lesioned animals there was a highly significant negative correlation between tail skin temperature and tail-flick latency. Multiple regression analysis showed that the effect of lesioning on tail-flick latency was non-significant when the effect of skin temperature was taken into account. Thus the reduced tail-flick latency after lesions of descending serotonergic pathways, usually interpreted as increased nociception, may be due to changes in tail skin temperature.