INTRODUCING SIBS: ‘SUBSTRATE INDEPENDENT BENTHIC SAMPLER’ FOR HARD AND MIXED-BOTTOM HABITATS: A PROOF OF CONCEPT STUDY

 As is the case in most countries, the  Norwegian standard for monitoring  of  organic impacts of salmon farming is centered

 around the analysis of chemical and biological parameters of soft-sediments habitats . However, m any fish farms are situated in areas with hard or mixed substrates and  this is likely to increase given the anticipated

 shift to more  physically  dynamic sites.

Although a nalogous changes are probably occurring on these mixed-bottoms

habitats , our knowledge of

any

potential interactions is severely lacking , and more critically,

 are going largely unmonitored due to the absence of a suitable sampling method.

 There are however emerging alternative biological indicators that may provide a solution. Recently, several studies have demonstrated

the potential of using genetic material from micro-organisms (e.g. bacteria, foraminifera etc.), assessed

 through rapid, high-throughput sequencing techniques, to discern benthic enrichment. To date, these have been necessarily restricted

to sampleable soft-sediment habitats. The small, ubiquitous, highly abundant and diverse nature of these

organisms means that they are likely to be present in the biofilms and/or flocculent layers that

 overly most hard- and mixed-bottom substrates.

 Here we present the first set of results using eDNA to describe the microbial communities of samples collected using a newly developed ‘Substrate Independent Benthic Sampler’ device. Samples were obtained from sand, shellsand , gravel, and bedrock using a low-cost surface operated suction device and are compared to more conventional  microbial  eDNA samples  from soft-sediments  and to macrofauna samples, where feasible. Minor differences were observed between sample types and farms, but in general, very g ood congruence wa s observed between the datasets with respect to distance from farm and anticipated benthic effects. Sampling of flocculent material overlying all substrates provides a potentially vital monitoring tool for the management of fish farm effects in the future.