A new research programme on fjord- and coastal ecology

In Porsangerfjord, Northern Norway, the kelp beds have disappeared due to overgrazing from sea urchins. During the same period, the coastal cod became severely depleted in the fjord. Recently, kelp and sprat experienced severe setbacks in the Hardangerfjord, Southern Norway. The Institute of Marine Research launches now a new, Strategic Institute Programme to explore the recent events observed in the ecosystems of these fjords.

The new research programme, EPIGRAPH, is aimed at improving the causal relationships and dynamics underlying the observed changes in the two fjord ecosystems. EPIGRAPH is an acronym for “Ecological Processes and Impacts Governing the Resilience and Alternations in the Prorsangerfjord and the Hardangerfjord”.

The Porsangerfjord

The rich kelp beds Laminaria hyperbora in the Porsangerfjord disappeared due to overgrazing by the green sea urchin, Strongylocentrotus droebachiensis. However, we do not know why this sea urchin suddenly became able to decimate the highly productive kelp forests. Simultaneously, the abundance of local cod, Gadus morhua, suffered a severe decline. Are there any relations between these events? The disappearance of kelp beds and the reduction of coastal cod are phenomenon observed in large parts of the coast in Central and Northern Norway. However, the Porsangerfjord is a suitable model area to study the ecological interactions and causal relationships. Just now, we are experiencing a large scale “natural experiment” as the Porsangerfjord is about to be invaded by the red king crap, Paralithodes camtschaticus, a new introduced species which has sea urchins high on his diet.

The working hypothesis of EPIGRAPH is that the ecosystem in the Porsangerfjord is governed by predation processes and is an example of a top-down regulated system. Five sub-projects are designed to challenge this hypothesis and they cover transport and distribution of egg and larvae from cod and red king crab, population dynamics and food availability in fish stocks, foraging behaviour of resident populations of harbour Phoca vitulina and grey Halichoerus grypus seals, interactions between kelp, sea urchin and red king crab and finally the biodiversity and productivity of benthic communities. These sub-projects will generate data for modeling the ecosystem using Ecopath with Ecosim.

The Hardangerfjord

The occurrence of the macro algae vegetation Laminaria saccharina in the Hardangerfjord is currently rapidly declining. Simultaneously, the abundance of sprat Sprattus sprattus, is severely reduced. Sprat was formerly a key species in the ecosystem of this fjord. We do not know the effects of an apparent increase of the nutrients in the fjord waters and if there are any causal links to the observed alternations in kelp vegetation and fish populations. The Hardangerfjord is an important area for fish farming, and we do not fully understand the interactions between wild and escaped farmed salmon Salmo salar, and the effects of salmon lice Lepeoptheirus salmonis on wild fish.

The working hypothesis of EPIGRAPH is that bottom-up processes govern the ecosystem of the Hardangerfjord and that nutrients play an important role in the causal relations and dynamics underlying the recent changes observed in the fjord. Eight sub-projects are established to challenge this hypothesis and the sub-projects cover inter alia oceanographic conditions, algae vegetation, zooplankton, population biology of sprat, abundance and diet of piscivorous fish and marine mammals, genetics of sprat, interaction of wild and escaped farmed salmon, and finally vulnerable habitats.

About EPIGRAPH

The acronym has an additional message: EPIGRAPH means “the script on the outside”, usually used on houses to explain their content. The EPIGRAPH programme is aimed at revealing improved understanding of the content of the fjord ecosystems, identify the essential interactions and the dynamics and functional relations between trophic levels. An important aspect is to explore how human activities impact the ecosystems. The fjords are utilized for a range of purposes including as recipient for run offs from cities, agriculture, industry and fish farms, they are used for transport, as spawning and nursing areas for important fish stocks that are harvested through commercial and recreational fisheries. We anticipate that the outcome of the programme will be of great importance for the development of holistic management plans for Norwegian fjord- and coastal waters.

EPIGRAPH is a collaborative effort among the Institute of Marine Research, the universities of Bergen, Tromsø, Ås and St Andrews of Scotland, NIVA and the Finnmark University College. The collaborators of EPIGRAPH will meet for annual conferences where the main aim is to draw on comparative studies in two ecosystems that possibly are governed by different mechanisms. The annual conferences will be convened in Porsanger and Hardanger, high on the agenda will be dialog with local authorities and the general public.