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Tube-dwelling and burrowing polychaetes, crustaceans, bivalves and echinoderms are important benthic fauna groups, extensively used in monitoring of environmental status.

Biodiversity is a useful tool for monitoring extent and duration of man made impacts to the marine environment. Activities like sewage discharge, aquaculture and drilling for petroleum resources are activities being effectively monitored by following successions in marine invertebrate communities. In this type of environmental monitoring, the fact that different species and species-groups react differently to external impacts is used, and variations in time and space in species composition of sessile bottom faunal assemblages is regularly monitored.

Benthic faunal communities, which often comprise more than 10000 individuals of more than 150 species per square m² are among the richest and most diverse faunal assemblages in the world. In Arctic areas, new benthic animal species are frequently found. To fully understand and monitor environmental change using benthic communities, knowledge on the individual species (how they look), reproductive strategy, life cycle and tolerance of environmental variation is essential.

One of the tasks of ASBD is to further our understanding of the benthic fauna in the area, and the processes that affect them. This is a direct contribution to improved interpretation of the baseline and follow-up surveys that take place routinely around the sites of petroleum exploration.

In order to do this, we need to improve our knowledge of the sea floor in the area, because several factors that may affect benthic faunal communities exist, but these are not taken into account during routine surveys. Such factors include:

macrobenthic foraminifera (e.g. Hyperammina);
dense mats of sponge spicules in certain areas off Finnmark:
pock-marks, trawl-tracks, historical ice-scours;
other geo-physical/biological sediment processes (bioturbation, microbial activity, implications for break-down processes etc.)

Pock-marks, gas seeps and ice scour

The existence of pockmarks have been recognised for decades

The existence of numerous pockmarks in the Barents Sea has been recognised for decades, and a number of geochemical studies have been carried out in recent years. Recent studies have investigated the structure, morphology and possible formation of pockmarks around the Goliat field. The biodiversity in and around pockmarks has been investigated in the Oslofjorden and in the Troll area of the Norwegian Sea, but to date there is no published study of the biodiversity of pockmarks in the Barents Sea. The MAREANO project has conducted underwater filming and grab sampling in several pockmarks in the Barents Sea, but the results are not yet fully published.

Last Updated (Wednesday, 04 May 2011 11:43)

Sponge spicule and macrofaunal foraminifera

Benthic faunal sample showing the a dominance of macrofaunal foraminiferans, mostly Hyperammina subnodosum (thin, reddish-brown thin stick-like objects in the sample). Photo Rune Palerud.

In the Barents Sea and particularly off the coast of northern Finnmark, large areas of the sea floor is covered in dense mats of sponge spicules, originating from the nearby sponge grounds. These present a serious challenge for benthic faunal surveys in two ways. Practically, the spicules cause physical damage to soft-bodied fauna such as polychaete worms during the sieving process and in its worst form can make many of the specimens unidentifiable (the spicules penetrate the epithelium, and the specimen either turns ‘inside-out’ during fixation, or it fragments). Secondly, a dense mat of spicules on the sediment surface must alter the physical properties of the sediment-water interface, and other habitat characteristics. Despite this, the presence of sponge spicules is not considered in the survey analyses, other than a mention in the sampling log.

Last Updated (Wednesday, 04 May 2011 11:58)

Mechanical disturbance

Cold corals are particularly suspectible to physical disturbance.

Much attention is paid to the real and potential disturbance of petroleum exploitation, but few discussions place this in context of other impacts. In the southern Barents Sea/Lofoten area, there has been an intensive fisheries industry for many decades, and much bottom trawling is carried out in the area. With the opening of the southern Barents Sea and now also the Lofoten area, the debate surrounding the co-existence of petroleum and fisheries industries is heated.

Last Updated (Wednesday, 04 May 2011 11:40)

Taxonomy

Borstenwurmer des Meeres. A variety of marine worms. In: Das Meer by Matthias Jacob Schleiden, 1804-1881.

The fundamental building-block for all analyses involving biodiversity is to be able to name organisms correctly.

In the North Sea, the benthic fauna has been studied for generations, and many of the taxonomic problems have been solved. However, as we move into the mixed waters of the Barents Sea-Lofoten area, the problems increase.

Last Updated (Monday, 21 March 2011 13:20)

Large scale benthic analysis

Benthic faunal analyses have been carried out in the Region IX area since 1998, and to date more than 150 stations have been sampled. These have mostly been in connection with routine offshore sediment surveys commissioned by the relevant petroleum operators. The data are stored in the national Environmental Monitoring Database (MOD). The results of the individual surveys are available on the Norwegian Pollution Control Authority web site (www.sft.no), but the data have never been analysed as a whole, nor in comparison with MOD data from regions farther south.

Last Updated (Thursday, 24 February 2011 15:21)