The key to understand the environmental effects of oil and gas activities depends upon differentiating natural variability and disturbance to biotic assemblages, from those brought about by production activities. A decision on whether a particular location is adversely impacted by human activities can only be made by understanding (1) what is a “normal” (unimpacted) assemblage for a particular location, and (2) how much variability in time and space might naturally occur. Deviations greater than natural variability, that are detected using appropriate sampling designs, may then be attributed to the putative source of disturbance. Variability in assemblage structure of marine macrobenthos is usually manifest on multiple spatial scales, from small-scale patchiness to regional-scale gradients. Therefore, multi-scale sampling designs are required to determine if oil & gas activities affects soft-bottom marine assemblages. In this study we sampled the northwestern Adriatic gas field over c. 80 km of coastline (from Ravenna to Rimini), using a hierarchical nested design at spatial scales varying from hundreds of metres to tens of kilometres. Very strong depth and latitudinal gradients dominate the dataset at large scales, and these gradients also affect variability at smaller scales, indicating that the benthos in this area are not subject to high levels of patchiness. Sampling at different distances from gas platforms reflects the positioning of the samples in space, rather than indicating any significant effect derived from the presence of platforms. The only exceptions occurred where samples very close to platforms were dominated by the mussel Mytilus galloprovincialis which had become dislodged from platform legs and formed dense mats on the bottom. Although sample processing is not yet complete, preliminary analyses indicate that gas platforms have minimal effects on Adriatic macrobenthos.
A multi-scale impact assessment of effects of north-western Adriatic gas fields on marine macrobenthos - BIODIVADR. 2007
ABBIATI M.;AIROLDI L.;
2007
Abstract
The key to understand the environmental effects of oil and gas activities depends upon differentiating natural variability and disturbance to biotic assemblages, from those brought about by production activities. A decision on whether a particular location is adversely impacted by human activities can only be made by understanding (1) what is a “normal” (unimpacted) assemblage for a particular location, and (2) how much variability in time and space might naturally occur. Deviations greater than natural variability, that are detected using appropriate sampling designs, may then be attributed to the putative source of disturbance. Variability in assemblage structure of marine macrobenthos is usually manifest on multiple spatial scales, from small-scale patchiness to regional-scale gradients. Therefore, multi-scale sampling designs are required to determine if oil & gas activities affects soft-bottom marine assemblages. In this study we sampled the northwestern Adriatic gas field over c. 80 km of coastline (from Ravenna to Rimini), using a hierarchical nested design at spatial scales varying from hundreds of metres to tens of kilometres. Very strong depth and latitudinal gradients dominate the dataset at large scales, and these gradients also affect variability at smaller scales, indicating that the benthos in this area are not subject to high levels of patchiness. Sampling at different distances from gas platforms reflects the positioning of the samples in space, rather than indicating any significant effect derived from the presence of platforms. The only exceptions occurred where samples very close to platforms were dominated by the mussel Mytilus galloprovincialis which had become dislodged from platform legs and formed dense mats on the bottom. Although sample processing is not yet complete, preliminary analyses indicate that gas platforms have minimal effects on Adriatic macrobenthos.
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