In a squeeze: Epibiosis may affect the distribution of kelp forests

The processes limiting the population recovery of the kelp Saccharina latissima after recent large‐scale loss from the south coast of Norway are poorly understood. Previous investigations do, however, suggest that the impacts of biotic interactions (epibiosis and competition) and increased water turbidity are important. We investigated the depth‐related patterns of growth, epibiosis, and mortality in two sample populations of kelp, from the south and the southwest coast of Norway. The investigations were performed over a period of seven months, in a crossed translocational study, where kelps were mounted on rigs at six depths (1, 3, 6, 9, 15, and 24 m). In a second experiment, the amounts of light blocked by different epibiont layers growing on the kelp frond were investigated. While growth decreased with depth in spring and summer, the kelp grew faster at 15 m than at shallower depths in fall. Survival was low both in shallow water and below 15 m depth. Epibionts covered the kelp growing at depths from 1 to 9 m, and the laboratory study showed that the coverage may have deprived the individuals of as much as 90% of the available light. Although the depth‐related results we present apply—in the strictest sense—only to kelp translocated on rigs, we argue that the relative patterns are relevant for natural populations. Growth and survival of S. latissima is likely to be reduced by heavy loads of epibionts, while depths where epibionts are sparse may be close to the lower limit of the kelps depth distribution along the south coast of Norway. This suggests that a vertical squeeze, or narrowing of the distribution range of kelp forests may be occurring in Norway.publishedVersio

Undersøkelse av hydrografiske og biologiske forhold i Indre Oslofjord Årsrapport 2022

Prosjektleder: André StaalstrømDen økologiske tilstanden i vannmassene er «moderat» på alle stasjoner for perioden 2020-2022. Den utslagsgivende parameteren er dårlige oksygenforhold, som kan knyttes til overgjødsling som fører til for mye nitrogen i vannmassen. I bassenget Håøybukta er det bedre oksygenforhold enn i resten av fjorden, og reketettheten viste seg å være mer enn dobbelt så høy som på de øvrige stasjonene. Helsetilstanden til blåskjell i Indre Oslofjord er ikke tilfredsstillende og ansees for å være sterkt stresset. Dette kan skyldes stor forekomst av giftige alger av slekten Dinophysis som ble observert i 2022. Det var forekomst av trådformede ettårige alger (lurv) på de syv undersøkte stasjonene, og indeksen for nedre voksegrense ga moderat tilstand for alle stasjoner som ble klassifisert, og ved Steilene er det dokumentert en negativ trend. Samlet sett så gir overvåkningen i 2022 et enda tydeligere signal enn tidligere om at konsentrasjon av nitrogen i vannmassene må reduseres.Fagrådet for vann & avløpsteknisk samarbeid i indre OslofjordpublishedVersio

Three decades of change in the Skagerrak coastal ecosystem, shaped by eutrophication and coastal darkening

Global coastal ecosystems are under accelerating pressure from human activities and climate change. In this study we explore a long-term time series (mostly 1990–2016) from major Norwegian rivers, together with coastal time series from the Norwegian Skagerrak coast. The aims are to: 1) analyse long-term trends in riverine loadings to Skagerrak, changes in coastal water quality and pelagic and benthic species composition, and 2) to describe the relationships between human drivers (eutrophication and coastal darkening) and community structure of benthic communities. Riverine discharge and transport increased by 23–85% over the time period, corresponding to a 40–78% increase in concentrations of suspended particulate material in coastal waters and reduced surface salinity, connected to the reported coastal darkening of coastal waters. There was a worsening in ecological status for hard-bottom benthic communities (0–30 m) and a reduction in the lower growth depth limit of several macroalgae species. A structural shift in the community composition from macroalgae towards increased abundance of animals was found to be related to coastal darkening and reduced eutrophication. The concentration of coastal inorganic nutrients (DIN, PO4) declined by 27–36%, in response to management efforts to reduce eutrophication in European regional seas. Results indicate that reduced eutrophication was related to increased ecological status of the deep soft-bottom community (350 m), with a reduction in opportunistic polychaetes and an increase in filter feeding bivalves. This work highlights how climate change and other human-induced changes in a boreal ecosystem intensifies land-ocean interactions, and calls for more adaptive monitoring, where traditional water quality programs and policies need to evolve iteratively as new information emerges and the major drivers of the systems change.publishedVersio

Kunnskapsoppsummering om marine områder som er viktige for karbonlagring

Prosjektleder: Gunhild BorgersenDenne rapporten presenterer en kunnskapsoppsummering om marine områder og naturtyper som er viktige for karbonlagring i Norge. Oppsummeringen omfatter sammenstilling av eksisterende kunnskap om naturtypenes utbredelse og evne til å binde og lagre karbon, mulige trusler mot disse naturtyper, samt identifisering av kunnskapshull. Marine naturtyper som omtales er tareskog, tang, ålegrasenger, helofytt-saltvannssump, bløtbunnsområder, plante- og dyreplankton, fisk og pattedyr. Arbeidet inkluderer i tillegg et online kartverktøy som sammenfatter informasjon om arealutbredelser og karbonlagring knyttet til de ulike naturtypene fremhevet i rapporten. Kartverktøyet er tilgjengelig som selvstendig webapplikasjon, mens bruken og mulighetene er beskrevet i rapporten.MiljødirektoratetpublishedVersio

Undersøkelse av hydrografiske og biologiske forhold i Indre Oslofjord Årsrapport 2021

Prosjektleder/Hovedforfatter André StaalstrømVannkvaliteten er moderat på alle målestasjonene i Indre Oslofjord, inkludert Drøbaksundet. Det var dypvannsfornyelse i Bunnefjorden i 2021, kun litt over to år etter forrige dypvannsfornyelse. NFR sitt nye dypvannsutslipp i Bunnefjorden har gitt signifikant mer vertikal omrøring, som sannsynligvis var medvirkende til at dypvannet ble fornyet tidligere enn forventet. Drøbakjetéen har en positiv virkning på den vertikale omrøringen i fjorden og må bevares. I november 2021 ble det observert den største planteplanktonoppblomstringen i Oslofjorden på flere tiår.publishedVersio

Kelp forest distribution in the Nordic region

Kelp forests are productive coastal ecosystems that provide a range of ecosystem services. Mapping the distribution and area occupied by kelp forests is a critical step to identify their ecosystem functions and services, including their role in the carbon cycle, and to detect changes in their distribution. We compiled quantitative data of the dominant genera Laminaria and Saccharina across the Nordic region, allowing us to separate kelp forests (areas with dense or moderately dense kelp coverage) from occurrences of single or few individuals. By fitting boosted regression trees to the compiled data, we modelled and predicted the distribution of kelp forests across the Nordic region. Despite the large scale of the analyses, the models captured well the kelps’ environmental affinities and predicted the presence of kelp forests with high accuracy. Dense kelp forests are found along the rocky shores of all the Nordic countries, except in the brackish Baltic Sea, with largest areas in Norway, Greenland and Iceland. The results of this study set the scene for future studies on the importance of kelp forests in the Nordic region, including their contribution to the marine carbon budget.Kelp forest distribution in the Nordic regionpublishedVersio

"Hanging gardens" - comparing fauna communities in kelp farms and wild kelp forests

A growing need for food is causing increased interest for seaweed farming globally. This requires knowledge of the industry’s effects on the marine environment. We therefore aimed to explore the communities hosted by a kelp farm compared to that of wild kelp forests. The study was performed in mid-western Norway. Kelp associated fauna were collected from farmed kelp (Saccharina latissima and Alaria esculenta), in wild kelp forests (S. latissima, A. esculenta and Laminaria hyperborea), and from fauna traps in the water column. The study showed that the kelp farm had lower taxa abundance and richness and a lower biodiversity than the wild kelp forests. Nonetheless, the farmed kelp hosted many associated species, with communities different from what was found on ropes without kelp (i.e., in the water column). The fauna communities among the farmed kelp were more similar to what was found in the wild L. hyperborea kelp forest than to its wild counterparts. The difference between the fauna communities of ‘old’ and ‘young’ farmed kelp (grown for 3 and 7 months, respectively) was not significant, but the fauna was dominated by the isopod species Idotea pelagica in the young forest and by amphipods, mainly belonging to the genus Caprella, in the older. The study contributes to our knowledge of kelp farms’ ecological role in the marine environment, which is of importance for today’s management as well as for ensuring a sustainable future development of the kelp farming industry.publishedVersio

Feltveileder for Kartlegging av marin naturvariasjon etter NiN (2.2.0).

Formålet med veilederen Veilederens hovedformål er å bidra til at resultatene av praktisk kartlegging i sjø i henhold til NiNs type og beskrivelsessystem blir så gode som mulig og sammenlignbare på tvers av kartleggere. Dette innebærer å beskrive hvordan, og i hvilken grad, den observerte naturvariasjonen bør forenkles under kartlegging. Veilederen skal oppsummere den kunnskapen som trengs for å kartlegge i sjø etter NiN, og i overenstemmelse med prinsippene som er omtalt i hovedveilederen (Bryn m. fl. 2018). Feltveilederen skal gi de generelle rammene for NiN-kartlegging i sjø, inkludert metodikk og verktøy, og har kartleggere som målgruppe. Denne feltveilederen dekker NiNs natursystemnivå med tilhørende type- og beskrivelsessystem for saltvannsbunnsystemer og marine vannmasser, og omfatter ikke andre deler av NiN. Veilederens Del D gir en beskrivelse av de ulike marine hovedtypene og miljøvariablene (LKMene) som definerer typeinndelingen. Denne delen gir også en veiledning til kartlegging av de ulike marine naturtypene på natursystemnivået for målestokkene 1:5 000, 1:20 000 og 1:100 000, i enkelte tilfeller også for målestokkene 1:500 og 1:2 500 (som er spesielt relevant for Fast fjærebeltebunn og evt. andre naturtyper som har liten arealutbredelse og som lar seg avgrense direkte i felt). Hovedveilederen (Bryn m. fl. (2018)) skisserer noen sentrale forutsetninger som en veileder for kartlegging av naturtyper avhenger av, blant annet at det finnes et type- og beskrivelsessystem som er tilpasset praktisk kartlegging. Det betyr at det må finnes tilstrekkelig erfaring med praktisk bruk av systemet. Disse forutsetningen er i all hovedsak ikke oppfylt for kartlegging i sjø. Det er derfor viktig å presisere at dette er en første-generasjons veileder for kartlegging i sjø etter NiN (versjon 2.2.0) på natursystemnivå. Etter hvert som denne veilederen testes i felt, vil erfaringer høstes og bidra til en videre utvikling og en revidering basert på nye erfaringer og evt. nye metoder som måtte utvikles.Feltveileder for Kartlegging av marin naturvariasjon etter NiN (2.2.0).publishedVersio

Pilotprosjekt - Kartlegging av marin natur i Møre og Romsdal. Årsrapport 2017

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Habitat features and their influence on the restoration potential of marine habitats in Europe

To understand the restoration potential of degraded habitats, it is important to know the key processes and habitat features that allow for recovery after disturbance. As part of the EU (Horizon 2020) funded MERCES project, a group of European experts compiled and assessed current knowledge, from both past and ongoing restoration efforts, within the Mediterranean Sea, the Baltic Sea, and the North-East Atlantic Ocean. The aim was to provide an expert judgment of how different habitat features could impact restoration success and enhance the recovery of marine habitats. A set of biological and ecological features (i.e., life-history traits, population connectivity, spatial distribution, structural complexity, and the potential for regime shifts) were identified and scored according to their contribution to the successful accomplishment of habitat restoration for five habitats: seagrass meadows, kelp forests, Cystoseira macroalgal beds, coralligenous assemblages and cold-water coral habitats. The expert group concluded that most of the kelp forests features facilitate successful restoration, while the features for the coralligenous assemblages and the cold-water coral habitat did not promote successful restoration. For the other habitats the conclusions were much more variable. The lack of knowledge on the relationship between acting pressures and resulting changes in the ecological state of habitats is a major challenge for implementing restoration actions. This paper provides an overview of essential features that can affect restoration success in marine habitats of key importance for valuable ecosystem services