SUSTAINable AQUAculture in the North: identifying thresholds, indicators and tools for future growth

The Norwegian salmon farming industry is predicted to grow substantially, especially in the less developed region of Northern Norway. It is critical for the national economy, the global reputation of the industry and the environment that this is planned, managed effectively and truly sustainable. The benthic environments in these Northern regions are thought to comprise predominantly hard and mixed bottom habitats. Unlike soft-sediment habitats, mixed and hard-bottom habitats are poorly studied and there is no established approach for monitoring aquaculture related effects. This situation is compounded by a lack of basic information about the specific organisms that are present, and their spatial distribution. Thus, there is a clear and pressing need to increase our knowledge about potential interactions between farm wastes and the mixed- and hard-bottom habitats of Northern Norway. The ?StustainAqua? project studied the environmental tolerances of some of the dominant and potentially important marine fauna of these habitats (e.g. sponges, corals, anemones etc.). The goals were to identify alternative biological indicators of ecosystem effects, to facilitate the development of a defensible method for environmental monitoring. Two alternate approaches were explored; one based on visual indicators of enrichment, and the other utilising modern next-generation sequencing techniques (environmental DNA) to examine both the veneer of mobile sediments that overlies most hard substrates, and the changes to the microbiomes of specific taxa in response to enrichment. The latter was achieved by conducting a translocation experiment with four species cultured in strategic proximities to a salmon farm. This project also aimed to increase capability for predicting the spatial extent of effects so that impacts to ecologically sensitive or valuable habitats can be avoided by developing new model input parameters and then improving and testing two of Norway's leading depositional models. The study effectively characterized epifauna communities found in the Altafjord area and in the process, developed a new cost-effective method for quantitative video surveys of benthic communities. Resulting data were then used used to describe ecological responses to waste, and to identify several useful indicator species. Four epifauna species targeted for translocation (Hormathia digitata, Craniella sp., Drifa florida, Polymastia sp.) revealed some potentially useful stress indicators that can be used to detect sublethal effects (i.e., signs of impact before the individuals are lost). An innovative substrate-independent benthic sampler (?SIBS?) was developed to sample directly from hard substrates which is proving capable of clearly elucidating organic enrichment gradients and should contribute significantly toward solving ?the hard-bottom problem?. Salmon feces decay and pellet break up experiments were conducted which yielded new input parameters for depositional models, which have been constructed for the three main study farms.

1. Epifauna habitats in northern Norway are now better described and we have some new information about their relative sensitivities to farm waste, which is critical for future farm planning, monitoring and management. 2. The visual survey technique coupled with the SIBS sampling device and potential sublethal effects indicators provides contribute significantly towards solving 'the hard bottom problem? with regards to fish farm environmental monitoring. 3. Knowledge of the distribution and sensitivity of the soft coral Duva florida has been utilised to inform assessment of a new farm situated in close proximity to a similar colony. Miljødirectoratet have sought advice from these findings and how they should undertake a similar monitoring exercise. 4. Knowledge, skills and technology obtained from the video survey work has been integral in the development of the new Alternativ overvåking av hard- og blandingsbunn ved marine akvakulturanlegg veileder.

Norway's large and important salmon farm industry is expected to grow substantially in the near future. Much of this expansion will occur in the north due to space availability and increasing sea temperatures. It is critical for both the national economy and the global reputation of the industry that this growth is planned and managed effectively and is sustainable - long-term. The benthic environments in these Northern regions are thought to be predominantly comprised of hard and mixed bottom habitats that are relatively unique. Unlike for soft-sediment habitats, many of the hard-bottom inhabitants are poorly understood in terms of their tolerance of farm derived-wastes, and critically, there is presently no defensible approach for monitoring the effects. This situation is compounded by a paucity of basic information on their composition and spatial distributions. Thus, there is a clear and pressing need to increase our knowledge about potential interactions between farm-derived wastes and the mixed and hard-bottom habitats of Northern Norway. This project plans to address this problem by studying the environmental tolerances of the prevalent fauna, identifying alternative indicators of ecosystem effects, and in doing so, developing novel approaches to environmental monitoring. Two potential alternate approaches will be examined; one based on visual indicators of enrichment, and the other utilising state-of-the-art next-generation sequencing techniques to describe the associated microbial communities. In addition, this projects aims to increase our ability to predict effects and to position farms such that overlapping farm effects can be avoided and any ecological sensitive or valuable habitats can be protected. This will be achieved by updating, validating and improving two leading depositional models, such that they are able to reliably predict the spatial distribution of organic wastes from the farms as well as the associated potential effects boundaries.