Human disturbance reduces diversity among seagrass fish communities

While human activity is known to impact a variety of ecosystems, the effect of human activity on coastal biodiversity is largely unknown. Coastal seagrass meadows are important nursery grounds for commercial and ecologically significant fish species. Globally, these ecosystems have declined at an average rate of seven per cent a year since 1990, making their preservation all the more urgent.

In a collaborative effort involving government, non-government organizations and academics examined 89 seagrass meadows across Canada’s Pacific Coast, including meadows in Saanich Inlet, Victoria Harbour and Sooke Harbour, disturbance was measured by the proportion of overwater structures such as ferry terminals and marinas, amount of shoreline modification, and the number of people living in a particular watershed. The study found that in areas with high levels of human disturbance, the same few fish species thrived. While hardy species such as the threespine stickleback dominated in high-disturbance areas, sensitive rockfish species and slow-swimming egg-guarders, such as pipefish and gunnel fish, were more likely to be found in areas with less human disturbance.