SOFTORG aims at experimentally investigating how various sources of organic matter influence structural and functional parameters of soft bottom benthos, including fate of organic carbon in sediments. The project was initiated as a pilot project financed by NIVA in 2015 and has got further funding for 2016.
Benthic systems act as a sink for organic and inorganic particulate materials that sediment from the water masses, but also as a regenerator of nutrients. Organic matter remineralization may be considered a key function of the benthic compartment and benthic processing largely determines the amount and composition of organic carbon buried in marine sediments. It has been hypothesized that fjords are hotspots of carbon burial because they receive high rates of organic material, and may thus play an important role in climate regulation. During the last decades, an increased amount of dissolved organic matter has been observed not only in rivers, but also in coastal waters. The fate of riverine carbon is to a large degree unknown, and one of the key questions is to understand the proportion of carbon that is buried in marine sediments. This same key question applies to the fate of kelp detritus in sediments. Over the past decades, dramatic regime shifts from kelp forests to barren areas have occurred, with major implications for the production and export of kelp detritus. Thus, changing kelp coverage caused by natural and/or anthropogenic stressors may have substantial implications in the structure and function of adjacent ecosystems like soft bottom communities. A comprehensive understanding of the nature and extent of kelp subsidy to these communities is still lacking. We will perform simulated seabed studies at NIVAs experimental facility at Solbergstrand, where organic matter with an assumed varying degree of bioavailability and nutritional value will be added to intact soft bottom cores. Structural (biodiversity, community composition and biomass) and functional parameters (oxygen consumption, nutrient fluxes and profiles) will be measured, and sediment processing assessed. The project will support the strategic work of the Norwegian Blue Forest Network (NIVA, IMR, and GRID-Arendal) by investigating the fate of kelp detritus in sediments and is also related to the ongoing NFR project KELPEX.
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