Long-Term Oceanographic and Ecological Research in the Western English Channel

Long-term research in the western English Channel, undertaken by the marine laboratories in Plymouth, is described and details of survey methods, sites, and time series given in this chapter. Major findings are summarized and their limitations outlined. Current research, with recent reestablishment and expansion of many sampling programmes, is presented, and possible future approaches are indicated. These unique long-term data sets provide an environmental baseline for predicting complex ecological responses to local, regional, and global environmental change. Between 1888 and the present, investigations have been carried out into the physical, chemical, and biological components (ranging from plankton and fish to benthic and intertidal assemblages) of the western English Channel ecosystem. The Marine Biological Association of the United Kingdom has performed the main body of these observations. More recent contributions come from the Continuous Plankton Recorder Survey, now the Sir Alister Hardy Foundation for Ocean Science, dating from 1957; the Institute for Marine Environmental Research, from 1974 to 1987; and the Plymouth Marine Laboratory, which was formed by amalgamation of the Institute for Marine Environmental Research and part of the Marine Biological Association, from 1988. Together, these contributions constitute a unique data series; one of the longest and most comprehensive samplings of environmental and marine biological variables in the world. Since the termination of many of these time series in 1987-1988 during a reorganisation of UK marine research, there has been a resurgence of interest in long-term environmental change. Many programmes have been restarted and expanded with support from several agencies. The observations span significant periods of warming (1921-1961; 1985-present) and cooling (1962-1980). During these periods of change, the abundance of key species underwent dramatic shifts. The first period of warming saw changes in zooplankton, pelagic fish, and larval fish, including the collapse of an important herring fishery. During later periods of change, shifts in species abundances have been reflected in other assemblages, such as the intertidal zone and the benthic fauna. Many of these changes appear to be related to climate, manifested as temperature changes, acting directly or indirectly. The hypothesis that climate is a forcing factor is widely supported today and has been reinforced by recent studies that show responses of marine organisms to climatic attributes such as the strength of the North Atlantic Oscillation. The long-term data also yield important insights into the effects of anthropogenic disturbances such as fisheries exploitation and pollution. Comparison of demersal fish hauls over time highlights fisheries effects not only on commercially important species but also on the entire demersal community. The effects of acute ("Torrey Canyon" oil spill) and chronic (tributyltin [TBT] antifoulants) pollution are clearly seen in the intertidal records. Significant advances in diverse scientific disciplines have been generated from research undertaken alongside the long-term data series.

The bactericidal effect of dendritic copper microparticles, contained in an alginate matrix, on Escherichia coli

Although the bactericidal effect of copper has been known for centuries, there is a current resurgence of interest in the use of this element as an antimicrobial agent. During this study the use of dendritic copper microparticles embedded in an alginate matrix as a rapid method for the deactivation of Escherichia coli ATCC 11775 was investigated. The copper/alginate produced a decrease in the minimum inhibitory concentration from free copper powder dispersed in the media from 0.25 to 0.065 mg/ml. Beads loaded with 4% Cu deactivated 99.97% of bacteria after 90 minutes, compared to a 44.2% reduction in viability in the equivalent free copper powder treatment. There was no observed loss in the efficacy of this method with increasing bacterial loading up to 10(6) cells/ml, however only 88.2% of E. coli were deactivated after 90 minutes at a loading of 10(8) cells/ml. The efficacy of this method was highly dependent on the oxygen content of the media, with a 4.01% increase in viable bacteria observed under anoxic conditions compared to a >99% reduction in bacterial viability in oxygen tensions above 50% of saturation. Scanning electron micrographs (SEM) of the beads indicated that the dendritic copper particles sit as discrete clusters within a layered alginate matrix, and that the external surface of the beads has a scale-like appearance with dendritic copper particles extruding. E. coli cells visualised using SEM indicated a loss of cellular integrity upon Cu bead treatment with obvious visible blebbing. This study indicates the use of microscale dendritic particles of Cu embedded in an alginate matrix to effectively deactivate E. coli cells and opens the possibility of their application within effective water treatment processes, especially in high particulate waste streams where conventional methods, such as UV treatment or chlorination, are ineffective or inappropriate.