Researchers create report card for quantifying human impacts on coastal ecosystems

Along Canadian coastlines, marine plants form important and extensive habitats such as seagrass meadows, kelp forests, and rockweed beds that provide food and shelter to a wide variety of animals, store large amounts of carbon, increase biodiversity, and prevent coastal erosion.

Unfortunately, their nearshore location makes these habitats particularly vulnerable to the many human activities that occur both on land and in the sea. Many management agencies have recognized the importance of protecting these nearshore plant-based ecosystems, and many countries are committed to including them in marine protected areas or other conservation zones.

Read this open access paper on the FACETS website.

However, it remains unclear how to select areas for protection or other management measures given the wide variety and different intensities of human activities along our coasts.

Researchers have developed a comprehensive human impact metric that resembles a report card assessing which human impacts are affecting coastal ecosystems by where and how much. This metric includes 12 impact scores from land- and sea-based human activities including land-use practices, nutrient run-off, water quality, invasive species, fishing, and aquaculture.

Furthermore, the metric includes activities occurring at the local scale directly adjacent to a habitat as well as those occurring throughout a coastal bay or estuary.

This human impact metric was then applied to 180 seagrass beds in 52 bays across Atlantic Canada. Our results reveal a wide range and intensity of impact scores that provide insight into where coastal bays and seagrass beds are most affected by human activities and thus need management attention.

For example, in Prince Edward Island and New Brunswick many seagrass beds are affected by high nitrogen loading and shellfish aquaculture, while those along the Atlantic coast of Nova Scotia are more affected by invasive species and fishing. On the other hand, our results also show where coastal bays and seagrass beds are least affected by human activities, which would be ideal places for protection and conservation.

Lastly, results reveal several cases where the intensity at larger bay-scale impacts are different from local-scale impacts, emphasizing the need for measuring and managing impacts at multiple spatial scales.

The paper highlights the implications of the new research for management and conservation planning, and the potential application of the impact metric to other coastal regions and habitats in Canada and beyond.

Read the full paper — A human impact metric for coastal ecosystems with application to seagrass beds in Atlantic Canada by Grace E.P. Murphy, Melisa C. Wong and Heike K. Lotze.