Is long-term ecological functioning stable: The case of the marine benthos?

It is widely acknowledged that human activities are contributing to substantial biodiversity loss and that this threatens ecological processes underpinning human exploitation of ‘ecosystem services’ (defined by the Millennium Ecosystem Assessment as ‘the benefits people obtain from ecosystems’). In the present study we consider three ‘intermediate ecosystem services’ in both contemporary and ancient marine systems and although ‘ecosystem services’ per se did not exist in the Jurassic our study seeks to consider the future provision of these services and so the term is retained. We consider the temporal patterns in benthic marine ecosystems: (1) spanning four decades at two offshore stations in the North Sea, UK and (2) over millennial scales in Late Jurassic UK palaeocommunities. Biological traits analysis is used to link changes in taxonomic composition to variations in ecological functioning and the potential supply of three ‘intermediate’ ecosystem services: the ability to provide food to fish and other predators, benthic nutrient regeneration and carbon cycling. We examine whether changes in taxonomic composition drive temporal variation in functioning, whether this variation increases over time and the extent to which species turnover is comparable in contemporary and ancient systems. Taxonomic variability was of a similar magnitude in all three systems and there was evidence for changes in functioning linked to changes in several (key or rivet) taxa. During other periods resilience maintained functioning in the face of taxonomic change. These results suggest that in these benthic systems the Biodiversity–Ecosystem Functioning relationship is idiosyncratic, but a degree of temporal stability in functioning is maintained such that the ecosystem services they underpin would also be stable during decadal and longer-term changes

Discards in North Sea fisheries: causes, consequences and solutions

Discards refer to that part of the catch returned to the sea during fishing operations. This study assesses the consequences, causes, and potential solutions to the discard problem using the example of North Sea fisheries. Fishermen's immediate objectives during fishing operations and the low confidence in projected gains from discard reduction measures have promoted use of unselective trawls while the poor enforcement of the quota system has exacerbated discard quantities. It is concluded that a reduction in discard rates is required for a long-term solution to the ecological and economic costs of discarding and the development of fishing opportunity incentives can promote the use of more selective fishing techniques.Discards North Sea Fisheries management Fishermen's behaviour

Approaches to classifying benthic habitat quality

Implementing ecosystem-based management requires methods of assessing the quality of habitats to deliver the high-level objective of achieving healthy ecosystems. 'Habitat' has been interpreted in different ways and this has confused the debate over which attributes constitute 'quality'. Three definitions of quality for habitats are advanced: 'species', 'reference' and 'functional' . Operational measures associated with these are evaluated in terms of their utility to deliver policy objectives. It is concluded that functional definitions/measures of quality are most appropriate to deliver ecosystem-based management although measures of species and reference quality may support assessment of the functional quality of habitats.Habitats Ecosystem health Ecosystem-based management