A review of indicators and identification of gaps: Deep-sea habitats

Abstract

A range of national and international legislation, obligations and commitments aim to promote and maintain a healthy and biologically diverse marine environment from shallow coastal waters to the deep sea. In addition, a set of Contributory Marine Objectives (CMOs) have been developed to meet the Government’s overall vision for clean, safe, healthy, biologically diverse and productive seas. These objectives require sustained and routine observations of oceanic and coastal ecosystems to achieve their goals. This report evaluates the applicability of existing and suggested (where gaps have been highlighted) environmental indicators that can be used to monitor and assess the state of UK deep-sea habitats. These indicators are reviewed against potential anthropogenic pressures, ecosystem structure and function, as well as statutory obligations and CMOs.

The principal anthropogenic pressures that may have an impact on UK deep-sea habitats are identified as demersal fisheries, Oil and gas industry activities, land-based/shipping pollution and climate change. At present, there are no routine UK deep-sea environment monitoring programmes and the only protected area in UK deep water is the Darwin Mounds region. This investigation has identified seventeen potential indicators of impacts that can be mapped to the assessment framework, which will be used to implement an integrated monitoring programme.

The review of the anthropogenic pressures with regard to relevant indicators highlighted many gaps in current deep-sea habitat monitoring efforts. Gaps that could currently be covered or addressed by suggested indicators are:

• The impact of demersal fishing on UK deep-water habitats. This activity is not routinely monitored and its impact is unknown in the vast majority of UK deep-sea habitats, although it is thought to be the principle threat. (Indicator: photographic transects to measure extent, abundance and diversity of habitats).

• No routine monitoring programmes on the sustained impact of oil and gas industry activity on deep-sea habitats are in place, although the industry is required to perform initial environmental
impact assessments. (Indicator: community change around drill sites).

• The extent and impact of litter/debris (shipping, fishing and land-based) is unknown in the deep sea (Indicator: photographic transects, will show extent but not effects).

Anthropogenic pressures that cannot be addressed with current operational indicators may be addressed by indicators that are under development. Other gaps in monitoring effort require
more research to improve knowledge of the habitats and the impacts caused by the pressures. Also, monitoring effort should not focus only on ‘charismatic’ species (e.g. corals and sponges).

The critical review of the indicators highlighted significant gaps in their accurate implementation:

• The extent, abundance and diversity of specific UK deep-sea habitats are poorly understood, or remain unknown. Surveys still recover many species new to science and there is a paucity of
knowledge of deep-sea ecological processes.

• The UK does not currently monitor bioaccumulation of contaminants of any kind in deep-sea organisms.

• There is no ecotoxicological information for deep-sea organisms.

• Molecular and biochemical indicators are potentially useful in revealing contaminant exposure and the health of species, but such techniques remain under development.

The review of the indicators in addressing ecosystem structure and function revealed that while some can be used to address ecosystem structure (e.g., photographic transects to reveal extent of specific habitats, species abundance and diversity), there are presently no indicators available to address the issue of ecosystem function directly. Within the deep sea higher biodiversity appears to support higher rates of ecosystem processes and increased efficiency with which these processes are performed. Anthropogenic effects that negatively affect
biodiversity will therefore have a negative impact on ecosystem function. Indicators that monitor biodiversity may therefore act as proxies for monitoring ecosystem function.

A review of the current indicators in place suggests that regional and international statutory obligations and CMOs are not being fully addressed or fulfilled, primarily because there are no routine monitoring programmes in UK deep-sea waters. Photographic transects of the seafloor are potentially the most useful for routine monitoring and assessment of the fragile or vulnerable deep-water habitats found in UK waters and will help to address legal obligations. Such habitats include seamounts, carbonate mounds and reefs (notable for the presence of the deep-water coral, Lophelia pertusa), sponge aggregations, octocoral ‘gardens’ and chemosynthetic habitats (cold seeps and pockmarks). However, for monitoring, management and protection programmes to work successfully, we need to increase our knowledge of the location and ecology of these deep-sea habitats in UK waters.

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