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Prosjektleder: Trine Dale Dette er hovedrapport for prosjektet «Hvordan forebygge og håndtere episoder med skadelige alger og maneter i oppdrettsnæringen» finansiert av Fiskeri og havbruksnæringens forskningsfinansiering. Hovedmålet i prosjektet har vært å sammenstille eksisterende kunnskap, erfaringer og teknologiske løsninger som er i bruk for å forebygge og håndtere episoder med skadelige alger og maneter og basert på dette utforme og formidle anbefalinger og om mulig beste praksis i ulike situasjoner. Det er utviklet en prototype av et verktøy som på en enkel og lettfattelig måte fremstiller anbefalinger og beste praksis samt kunnskapen som danner bakgrunn for disse. Fiskeri og havbruksnæringens forskningsfinansiering.

Polar regions are currently warming at a rate above the global average. One issue of concern is the consequences on biodiversity in relation to the Northward latitudinal shift in distribution of temperate species. In the present study, lasting almost two years, we examined two phenological traits, i.e. the shell growth and behavioural rhythm of a recently re-established species in the high Arctic, the blue mussel Mytilus sp. We compared this with a native species, the Islandic scallop Chlamys islandica. We show marked differences in the examined traits between the two species. In Mytilus sp., a clear annual pattern of shell growth strongly correlated to the valve behaviour rhythmicity, whereas C. islandica exhibited a shell growth pattern with a total absence of annual rhythmicity of behaviour. The shell growth was highly correlated to the photoperiod for the mussels but weaker for the scallops. The water temperature cycle was a very weak parameter to anticipate the phenology traits of both species. This study shows that the new resident in the high Arctic, Mytilus sp., is a highly adaptive species, and therefore a promising bioindicator to study the consequences of biodiversity changes due to global warming. © 2020 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited.

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Dates of the different periods studied during the experience lasting 712 days, from 5 May 2016 to 17 April 2018. In total 8 periods studied: 2 polar days; 2 polar nights; 2 periods with days with light / dark alternation centered on the spring equinox (Spring LD alternation); 2 periods with days with light / dark alternation centered on the autumn equinox (Autumnal LD alternation). 16 days of record are missing due to electrical failure.

Individual double-plotted actogramms of valve opening amplitude (VOA) in the Kongsfjorden, Ny-Alesund, Svalbard recorded during 712 days (from 05/05/2016 to 17/04/2018) . (A) The blue mussels Mytilus sp. (n = 15) and (B) the scallops C. islandica (n = 7).

Upper panel and lower panel show the individual (doted lines) and mean (solid bold line) cumulative growth of the shells for Mytilus sp. (n = 15) and C. islandica (n = 6) respectively, during the 712-days of the in situ experiences for). SE: spring equinox; SS: summer solstice; AE: autumn equinox, WS: winter solstice.

Polar regions are currently warming at a rate above the global average. One issue of concern is the consequences on biodiversity in relation to the Northward latitudinal shift in distribution of temperate species. In the present study, lasting almost two years, we examined two phenological traits, i.e. the shell growth and behavioural rhythm of a recently re-established species in the high Arctic, the blue mussel Mytilus sp. We compared this with a native species, the Islandic scallop Chlamys islandica. We show marked differences in the examined traits between the two species. In Mytilus sp., a clear annual pattern of shell growth strongly correlated to the valve behaviour rhythmicity, whereas C. islandica exhibited a shell growth pattern with a total absence of annual rhythmicity of behaviour. The shell growth was highly correlated to the photoperiod for the mussels but weaker for the scallops. The water temperature cycle was a very weak parameter to anticipate the phenology traits of both species. This study shows that the new resident in the high Arctic, Mytilus sp., is a highly adaptive species, and therefore a promising bioindicator to study the consequences of biodiversity changes due to global warming.