Other Potential Agents of Change

Physical disturbance by storms

It is conceivable that severe storms could break up and scatter individual brittlestar beds. However, the decadal persistence of beds in areas such as the western Channel shows that at this geographic scale, populations can withstand the annual extremes of weather.

Pathogens or parasites

Dense aggregations of brittlestars would seem to offer ideal conditions for the rapid spread of pathogenic organisms or parasites, but so far no examples of this have been recorded. However, several examples are known of echinoderm populations that have been massively reduced by sudden oubreaks of epidemic disease. Cases include the mass mortality of the sea urchin Diadema antillarum throughout the Caribbean as a result of infection by a water-borne pathogen (Lessios, 1988), and the decimation of urchin populations in the North Atlantic by parasitic amoebae and nematodes (Hagen, 1995). Epidemic disease should therefore be considered as having the potential to significantly affect populations of bed-forming brittlestars.

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