Carbon stocks in Norwegian eelgrass meadows across environmental gradients.

Seagrass meadows are well-known for their capacity to capture and store blue carbon in sediments. However carbon stocks vary significantly between meadows, spanning more than three orders of magnitude on both local and global scales. Understanding the drivers of seagrass carbon stocks could help improve strategies for incorporating blue carbon into management plans.

Marine protected areas can be useful but are not a silver bullet for kelp conservation.

Kelp forests are among the most valuable ecosystems on Earth, but they are increasingly being degraded and lost due to a range of human-related stressors, leading to recent calls for their improved management and conservation. One of the primary tools to conserve marine species and biodiversity is the establishment of marine protected areas (MPAs). International commitments to protect 30% of the world's ecosystems are gaining momentum, offering a promising avenue to secure kelp forests into the Anthropocene.

Kelp carbon sink potential decreases with warming due to accelerating decomposition.

Cycling of organic carbon in the ocean has the potential to mitigate or exacerbate global climate change, but major questions remain about the environmental controls on organic carbon flux in the coastal zone. Here, we used a field experiment distributed across 28° of latitude, and the entire range of 2 dominant kelp species in the northern hemisphere, to measure decomposition rates of kelp detritus on the seafloor in relation to local environmental factors. Detritus decomposition in both species were strongly related to ocean temperature and initial carbon content, with higher rates of biomass loss at lower latitudes with warmer temperatures.

Homogenization and miniaturization of habitat structure in temperate marine forests.

Humans are rapidly transforming the structural configuration of the planet's ecosystems, but these changes and their ecological consequences remain poorly quantified in underwater habitats. Here, we show that the loss of forest-forming seaweeds and the rise of ground-covering 'turfs' across four continents consistently resulted in the miniaturization of underwater habitat structure, with seascapes converging towards flattened habitats with smaller habitable spaces. Globally, turf seascapes occupied a smaller architectural trait space and were structurally more similar across regions than marine forests, evidencing habitat homogenization.

Depletion of coastal predatory fish sub-stocks coincided with the largest sea urchin grazing event observed in the NE Atlantic.

In this contribution, we propose fishery driven predator release as the cause for the largest grazing event ever observed in the NE Atlantic. Based on the evolving appreciation of limits to population connectivity, published and previously unpublished data, we discuss whether overfishing caused a grazer bloom of the sea urchin (Strongylocentrotus droebachiensis) resulting in overgrazing of more than 2000 km kelp (Laminaria hyperborea) forest along Norwegian and Russian coasts during the 1970 s. We show that coastal fisheries likely depleted predatory coastal fish stocks through modernization of fishing methods and fleet.

Green gravel: a novel restoration tool to combat kelp forest decline.

Kelp forests are in decline globally and large-scale intervention could be required to halt the loss of these valuable ecosystems. To date kelp forest restoration has had limited success and been expensive and unable to address the increasing scale of ecosystem deterioration. Here we developed and tested a new approach: "green gravel".

Detrital carbon production and export in high latitude kelp forests.

The production and fate of seaweed detritus is a major unknown in the global C-budget. Knowing the quantity of detritus produced, the form it takes (size) and its timing of delivery are key to understanding its role as a resource subsidy to secondary production and/or its potential contribution to C-sequestration. We quantified the production and release of detritus from 10 Laminaria hyperborea sites in northern Norway (69.

Carbon export is facilitated by sea urchins transforming kelp detritus.

With the increasing imperative for societies to act to curb climate change by increasing carbon stores and sinks, it has become critical to understand how organic carbon is produced, released, transformed, transported, and sequestered within and across ecosystems. In freshwater and open-ocean systems, shredders play a significant and well-known role in transforming and mobilizing carbon, but their role in the carbon cycle of coastal ecosystems is largely unknown. Marine plants such as kelps produce vast amounts of detritus, which can be captured and consumed by shedders as it traverses the seafloor.

Can multitrophic interactions and ocean warming influence large-scale kelp recovery?

Ongoing changes along the northeastern Atlantic coastline provide an opportunity to explore the influence of climate change and multitrophic interactions on the recovery of kelp. Here, vast areas of sea urchin-dominated barren grounds have shifted back to kelp forests, in parallel with changes in sea temperature and predator abundances. We have compiled data from studies covering more than 1,500-km coastline in northern Norway.

A snap shot of the short-term response of crustaceans to macrophyte detritus in the deep Oslofjord.

A test deployment of a time-lapse camera lander in the deep Oslofjord (431 m) was used to obtain initial information on the response of benthic fauna to macroalgal debris. Three macroalgal species were used on the lander baited plate: Fucus serratus, Saccharina latissima and Laminaria hyperborea and observed during 41.5 hours.

New microsatellite loci for the green sea urchin Strongylocentrotus droebachiensis using universal M13 labelled markers.

Background: The green sea urchin Strongylocentrotus droebachiensis has a wide circumpolar distribution and plays a key role in coastal ecosystems worldwide by destructively grazing macroalgae beds and turn them into marine deserts, so-called barren grounds. In the past decades, large established kelp forests have been overgrazed and transformed to such barren grounds on the Norwegian coast. This has important repercussions for the coastal diversity and production, including reproduction of several fish species relying on the kelp forests as nurseries.

The influence of physical factors on kelp and sea urchin distribution in previously and still grazed areas in the NE Atlantic.

The spatial distribution of kelp (Laminaria hyperborea) and sea urchins (Strongylocentrotus droebachiensis) in the NE Atlantic are highly related to physical factors and to temporal changes in temperature. On a large scale, we identified borders for kelp recovery and sea urchin persistence along the north-south gradient. Sea urchin persistence was also related to the coast-ocean gradient.