ABSTRACT. Multivariate statistical analyses of data on environmental variables and benthic fauna from 14 oil and gas fields obtained from 24 surveys collected between 1985 and 1993 are presented. At all fields oil-based drilling mud was used. The purpose of this study was to investigate contamination gradients, assess effects on benthic fauna both spatially and temporally and to evaluate measures such as diversity indices, indicator species and multivariate analysls techniques in assessment of pollution. Results from analyses of baseline surveys of environmental variables and fauna were charactensed by a lack of distinct gradients in station placement, having a typical shot-gun pattern in PCA-, DCA-and MDS-ordination analyses. Likewise there was no consistency in which environmental variables correlated with the fauna. Contamination was assessed using all the physical and chemical data in classification and PCA-ordination analyses Clear patterns were found using 4 categories, conveniently termed initial, moderate, severe and gross. The categories were usually apparent as rings radiating from the platform. Initial contamination of the outermost areas at most fields was shown as elevated levels of barium and total hydrocarbons (THC) and sometimes also by elevated levels of zinc, copper, cadmium and lead. Three fields were studied in particular and showed contaminated areas of over 100 km2 (Valhall), over 15 km2 (Gyda) and over 10 km2 (Veslefrikk). After a period of 6 to 9 yr contamination had spread, so that nearly all of the outermost stations 2 to 6 km away from the platforms showed evidence of contamination. Thus, the existing sampling design is no longer suitable for assessment of the area contaminated. Effects on the fauna showed, as with contamination, 4 categories. Analyses hnking fauna and environmental variables indicated that the effects were mainly related to THC, barium and strontium, but also to metals like zinc, copper, cadmium and lead, which are all discharged in drill-cuttings. Effects on the fauna closely followed the patterns of contamination with only a few stations at each field that were contaminated not showing effects. Thus the areas showing effects were only slightly less than the areas contaminated. Subsequent to cessation of discharges biodegradation of oil and reduced concentrations of THC were observed. Yet there was an extension of areas where the fauna was affected several years after cessation of dnll-cutting discharges This may indicate that barite and related compounds associated with the discharges also have an environmental impact. However, preliminary results from fields using only water-based mud clearly indicate a reduction in environmental contamination and biological Impact, compared to effects reported here, for oil-based drill-cuttings. Diversity indices appl~ed to the data did not show the extent of effects and such Indices alone should not be used to interpret changes. The consistent patterns that the multlvariate techniques were able to detect showed that these methods...

The effects of pollution by organic matter, oil or industrial waste on marine communities are remarkably similar. Diversity values fall, biomass and numbers of organisms initially rise and then fall as the pollution load is increased. Diversity indices are, however, insensitive to pollution-induced changes and have to be assessed subjectively. Departure from a log-normal distribution of individuals among species offers a sensitive and objective method of assessing perturbation effects on communities. Under severe pollution stress, the dominant species are those which have a flexible life-history ranging from direct development to a planktonic larva and the ability to undergo short-term genetic selection. Species have a somewhat less flexible life-history strategy show increased abundance under conditions of slight pollution. The increase in abundance of seven or eight neither rare nor common species, which gives the departure from a log-normal distribution, is suggested as being the most significant and the earliest detectable change caused by pollution in a community. Thus the presence of a species in a polluted area may be more a question of life-history strategy than the tolerance of adverse environmental conditions. If this hypothesis is correct, considerable doubt must beplaced on the ecological relevance of data from toxicity tests.

Sanders (1968; Am. showed that, contrary to general opinion at the time, the deep-sea had high species diversity when compared with estuarine and coastal areas. This paper stimulated a series of studies and theoretical arguments aimed at explaining why the deep-sea had such high diversity. It is now accepted that the deep-sea has high diversity and it has been suggested that in the deepsea there may be up to 10 million new species yet to be described (Grassle & Maciolek 1992; Am. . Surprisingly, however, there have not been any recent comparisons between the fauna of the deep-sea and shallower areas. Here I present data from a survey taken from the continental shelf of Norway which allows a quantitative comparison to be made with recent data from the deep-sea. Species diversity is very similar to that of the deep-sea and speciesarea curves have almost identical slopes. These data suggest that the Norwegian continental shelf has species diversity equal to that of the deep-sea and thus leads one to question the paradigm that the deep-sea has exceptionally high diversity.

There are surely scientific, genetic or ecological arguments which show that differences exist between the relapsing fever (RF) spirochaetes and the Lyme borreliosis (LB) group of spirochaetes, both of which belong to the genus Borrelia. In a recent publication, Adeolu and Gupta [1] proposed dividing the genus Borrelia into two genera on the basis of genetic differences revealed by comparative genomics. The new genus name for the LB group of spirochaetes, Borreliella, has subsequently been entered in the GenBank database for some species of the group and in a validation list (List of new names and new combinations previously effectively, but not validly, published) [2]. However, rapidly expanding scientific knowledge and considerable conflicting evidence combined with the adverse consequences of splitting the genus Borrelia make such a drastic step somewhat premature. In our opinion, the basis of this division rests on preliminary evidence and should be rescinded for the following reasons:(1) The proposed split of the genus rests on differences in conserved signature indels (CSI) and conserved signature proteins (CSP) between LB and RF spirochaetes. A major omission in the study published by Adeolu and Gupta [1] is the exclusion of a Borrelia clade containing RF-like species that utilize hard ticks as vectors and reptiles as reservoir hosts [3,4].To identify proteins that are uniquely present in various groups of Borrelia, BLAST searches [5] were performed by Adeolu and Gupta [1] using each protein in the genomes of Borrelia burgdorferi sensu stricto (s.s.) B31 T and Borrelia recurrentis A1 as queries. Out of 1041 and 1390 protein coding genes (i.e. the number of proteins reported in GenBank accession numbers NC_011244 and NC_001318) present in B. recurrentis A1 and B. burgdorferi s.s. B31 T , respectively, 15 CSI (seven for LB, eight for RF) and 25 CSP (21 for LB, four for RF) were found to be unique for the respective groups. However, two of the four CSPs that are apparently unique for the RF group species are not found in all members of this group and therefore do not represent true signature proteins. Hence, just two CSPs and eight CSIs are unique to the RF group.