- Prof Stuart Jenkins
- Dr Hilmar Hinz
Long term change in the marine benthos
One of the most powerful approaches to understanding man's impact on marine ecosystems is to examine change at the population and community level over appropriate time scales. In terms of many of the most pervasive anthropogenic impacts in the marine environment (fishing pressure, climate change, eutrophication), this means analysing time series over multi-decadal scales.
The work of Norman Holme
Norman Holme, a staff member at the Marine Biological Association in Plymouth, UK developed an extensive body of work investigating the benthic ecology of the English Channel. He left an invaluable record of the marine benthos of this area over the period 1949 to 1980. We have utilised some of his work to attempt to understand both changes in distribution of soft sediment biota and changes in community compostion over a 50+ year time scale. Repeating a portion of his Channel wide survey of 1958/59 on board our research vessel, the Prince Madog in 2006, we showed that although there were some notable changes in distribution of benthic organsims, the magnitude of change was much lower than in some other components of the Channel ecosystem (interdial biota, fish, plankton) ( Hinz et al 2011).
The Eddystone Reef
Conservation agencies have a difficult task when selecting areas of the seabed to protect. A laudable aim is to apply protection from mans' activites (in many cases demersal fishing activities) in order that communities revert to those which bear some resemblance to communities prior to the implementation of industrialised levels of fishing. One question which is asked is: 'But what did the seabed used to look like and is it very different to that which we see today?' Funded by Natural England, we compared the present state of benthic community of gravel beds around the Eddystone Reef off the SW coast of England with the position over one hundred years ago.
Changes were clearly evident as expressed in Capasso et al (2010): Echinoderm diversity showed a clear reduction between 1895 and 2007. The sea urchins Echinus esculentus, Spatangus purpureus, and Psammechinus miliaris and large star-fish Marthasterias glacialis showed reductions in abundance,in some cases being entirely absent from the survey area in 2007. Polychaetes showed a shift from tubiculous species to small errant and predatory species such as Glycera, Nephtys, and Lumbrineris spp. Within the group Mollusca large species such as Pecten maximus and Laevicardium crassum decreased in abundance while small species increased.
A benthic time series in North Wales
In 2008 we re-established a benthic time series in North Wales by building on the work of Dr Ivor Rees who, with School of Ocean Sciences Masters students, had consistently sampled the infauna of Red Wharf Bay on the north coast of Anglesey over a period of 20 years. This area has not been subject to intensive fishing and thus provides the opportunity to examine relatively natural inter-annual variation in benthic assemblage composition over recent decades. Understanding of natural cycles of change provides an important context with which to view a range of anthropogenic impacts.
Keeping pace with climate change
Climate change is a major threat to biodiversity and distributions shifts are one of the most significant threats to global warming, but the extent to which these shifts keep pace with a changing climate is yet uncertain. Understanding the factors governing range shifts is crucial for conservation management to anticipate patterns of biodiversity distribution under future anthropogenic climate change. We evaluate changes in the distribution of 65 North Sea benthic invertebrate species between 1986 and 2000 by examining their geographic, bathymetric and thermal niche shifts and test whether species are tracking their thermal niche The velocity of climate change (VoCC) of mean SST accurately predicted both the direction and magnitude of distribution centroid shifts, while maximum SST did the same for contraction of the trailing edge. The VoCC of SBT was not a good predictor of range shifts. No good predictor of expansions of the leading edge was found. Our results show that invertebrates need to shift at different rates and directions to track the climate velocities of different temperature measures, and are therefore lagging behind most temperature measures. If these species cannot withstand a change in thermal habitat, this could ultimately lead to a drop in benthic biodiversity.
Hiddink, J. G., Burrows, M. T. and Molinos, J. G. (In press)
Temperature tracking by North Sea benthic invertebrates in response to climate change. Global Change Biology.
Capasso, E., Jenkins, SR., Frost, M., Hinz, H. (2010)
Investigation of benthic community change over a century-wide scale in the Western English Channel. Journal of the Marine Biological Association of the UK 90(6):1161-1172
Hinz H, Capasso E, Lilley M, Frost M, Jenkins JR. (2011)
Temporal differences across a bio-geographical boundary reveals slow response of sub-littoral benthos to climate change. Marine Ecology Progress Series 432: 69-82