Publication Abstract

Combining bioturbation and redox metrics: complementary tools for assessing seabed function.

S.N.R. Birchenough*, Parker, R.E.*, McManus, E.*,Barry, J.*

Marine systems are represented by a by a wide range of habitats. These systems are dynamic entities which have a high degree of complexity and may harbour high levels of biodiversity. Human-induced pressures (i.e. dredging, fishing, construction, pollution and others) often produce additional disturbance to these marine systems with repercussions for biodiversity.

Current national (e.g. Marine Bill, Charting Progress 2) and international (e.g. WFD, Habitats and Bird Directives, EUMSFD) legislation are focused on the quality and status of the marine environment. To this end, the UK has continued to work on the need to develop indicators which can assist with this process. This work has helped to identify the natural processes and man-made activities that are affecting marine systems. One of the marine descriptors within the EMSD is ‘seabed integrity’. This descriptor asks member states to ensure that the structure and function of ecosystems are safeguarded and benthic systems are not adversely affected.

To date, we have furthered our understanding of the seabed by, for example, studying benthic systems. For this purpose indicator tools, such as a suite of benthic indices, have been employed as measurers of ‘the health of benthic systems’. In most cases this information mainly relates to the structure of benthic populations. However, there is a gap in terms of what we can measure with regards to the function of the ecosystem and how individual benthic animals perform their roles within specific ecosystems. There is also not enough data to assess if the functions of the seafloor are safeguarded. This work has defined sediment function as an indicator to measure both carbon and nutrient cycling. These two processes are largely driven by the organisms controlling the redox potential of the sediments via bioturbation activities.