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HERMES-CORALFISH-2008
INTRODUCTION
Reef-forming colonial coldwater or deep water corals have a patchy distribution along the whole European Atlantic margin from north Norway to Mauritania. Even in the Mediterranean with its high deep-sea temperature of 13 degrees Celsius these .coldwater' corals are present, although much rarer than in the Atlantic. The main species in the Atlantic are Lophelia pertusa and Madrepora oculata, often growing together and sometimes even growing on each other. At some places these corals form patchy thickets of a few meters wide and about 1 meter high (e.g. Galicia Bank) in a hydrodynamic area, in other areas they can cover a large area with a more or less closed blanket of corals (e.g. Rockall Bank). In the Rockall Bank area these corals have formed many sea mounds, some of them 200-300m high. In the northern areas the corals can form real reefs, comparable to tropical corals, of kilometers long and tens of meters high, with colonies looking like huge cauliflowers with a diameter of about 2 meters (e.g. Sula- and Rxstreef, Norway). In the last decades our knowledge of the distribution, biodiversity and functioning of these coral communities has grown considerably in particular through projects funded by the European Commission, e.g. ACES, ECOMOUND, GEOMOUND and HERMES. However there are still many questions to solve and many areas to map.
Cold-water coral ecosystems are thought to be very rich in fauna, especially sponges, crustaceans, echinoderms and fishes. Therefore these ecosystems are classified as "hotspots for biodiversity" The HERMES project, financed by the EC, is set up primarily to investigate marine "hotspots of biodiversity" like cold-water coral reefs, to study how these ecosystems function, and to assess their importance for the oceanic environment. Apart from enlarging our scientific knowledge and understanding of the functioning of these reefs, it is also important that the new data can be used to set up rules for conservation or exploitation (e.g. fisheries, oil and gas exploration) for these vulnerable systems.
Within another project CORALFISH that is also funded by the EC and that started on 1 June 2008 the relation between fish and these coldwater coral communities is studied. Do these communities have an important role for certain fish populations as nurseries, as hiding and/or feeding places?
PROGRAM and GOALS for the HERMES/CORALFISH2008 EXPEDITION
During the past three years the department of Marine Ecology (MEE) of NIOZ has done research on Rockall Bank and Porcupine Bank (west of Ireland), Mingulay Reef (SE of the Outer Hebrides, Scotland) and on Tisler Reef (SW Sweden). For this expedition the targets were to study the coral communities of the Belgica Mound Province in the Porcupine Bight (first leg) and Hatton Bank (second leg).
BElGICA MOUNDS
The Belgica Mounds are situated on the eastern side of the Porcupine Bight. Several studies targeting these coral communities have been carried out. A summary of the research done so far and extra information based on ROV video footage can been found in Foubert et al. (2005). In December 2006 the area was designated as a special protected area of Ireland, and a special permit from Ireland is needed to carry out scientific research. Through the kind help of Dr. Eamonn Kelly (Wildlife Inspector)
this permit was received on short notice. Our goals for this area were to obtain some samples to study the biodiversity, biomass and density of macrobenthos, to study the foodweb by analyses of stable isotopes of selected benthic species, and to research the possible food resources. For Rockall Bank and Mingulay Reef we had found a clear correlation between the tidal currents, and temperature and fluorescence. From this we concluded that there is a regular lateral transport and downwelling of fresh material from the surface or the shallows to the coral community (Duineveld et al, 2007; Davies et al, submitted). For the Belgica Mounds we wanted to see if we could find any evidence that would also point to such a food transport mechanism.
For the CORALFISH project the fish population within the coral community will be studied by video surveys and by deploying a lander with baited HD Video camera.
Further for the BIOFUN project funded by the European Science Foundation the MOVE, a deep-sea crawler, was tested outside the Belgica Mound Province. The MOVE will be used during the BIOFUN expedition to the Galicia Bank in September 2008.
HATTON BANK
Hatton Bank is a large bank situated in the mid NE Atlantic Ocean. Together with the equally large Rockall Bank from which it is separated by a relatively shallow depression with a maximum depth of 1200m, it forms the Rockall Plateau. The top of the Bank lies at about 500m depth. The bottom fauna of Hatton Bank is not very well studied, and Roberts (2008) gives a first detailed study of some stations at Hatton Bank on the basis of seabed photographs taken during a baseline habitat mapping exercise in Aug 2005. Although several of the 13 photographic stations showed evidence of coral framework, it is difficult to assess the extension and abundance of coldwater corals on Hatton Bank from these data. Another source of coldwater occurrences at Hatton Bank is the database of the group of A Freiwald (Erlangen University), which was kindly offered to us. It contained 14 records of live corals, discovered by dredge, and originally reported by Chesher (1987), Long et al, (1999), Spiro et al. (2000) and Freiwald et al. (2002).
Hatton Bank is also an important deep-sea fishing area especially for the Spanish fishing fleet. In 2005, ICES reviewed the current knowledge of Lophelia pertusa distribution on Hatton Bank (ICES, 2005) following the request made by NEAFC. On the basis of this report NEAFC made a decision to prohibit bottom trawling and fishing with static gear (including bottom gillnets and longlines) on part of the bank from 1 January 2007 (http://www.neafc.org/measures/measures-2007/docs/rec-9-2007_hatton-rockall-closures.pdf). In 2007, ICES updated and corrected the information on Lophelia pertusa on Hatton Bank (Duran Muqoz et al., 2007a). NEAFC reacted by deciding to extend the Hatton closure to include the southern section of the bank from 1 January 2008 (NEAFC Recommendation IX.2007 and IX.2008, EC Regulation No 40/2008) (http://www.neafc.org/measures/current_measures/docs/09-rec_corals.pdf). Duran Muqoz et al. (2008) then presented new information and suggested an extra area for closure to fisheries on Hatton bank.
The goal of our expedition within the framework of the European HERMES project was to study part of Hatton Bank quite intensively to discover how extensive and abundant cold-water corals on Hatton Bank really are. Further we wanted to obtain enough data of the coral community to be able to compare the abundance, biomass, biodiversity and foodweb with those of Rockall Bank. We also tried to find evidence for a food source for these rich communities, as we had found at Rockall Bank and Mingulay Reef. And finally, in the framework of the European project CoralFish, we wanted to learn more about the importance of these coral communities for fish.
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station plot
Cruise report
Principal investigators
Measurement and sampling activities
Station list
Hydrographical data
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