Douglas B. Rasher
Bigelow Laboratory for Ocean Sciences

Robert Steneck
University of Maine

Matthew Suskiewicz
Bigelow Laboratory for Ocean Sciences

Kelp forests are the primary habitat of Maine’s nearshore waters. As the population of green sea urchins, which eat kelp, has declined, kelp forests are returning to their former glory beneath the surface. This project will identify how kelp forests are responding to changing environmental conditions. How fast and where are kelp forests returning? How are other inhabitants, such as crabs and urchins, affected by shifts in macroalgae? Are crabs eating urchins, and thus “locking Maine’s coastline into its historical seaweed-dominated state”?

Rasher, Steneck, and Suskiewicz will conduct subtidal surveys across five regions to estimate the diversity, relative abundance, and biomass of seaweeds on rocky reefs. They will compare the data to historical records from the same locations to determine changes over time (some of these data were collected with support from Sea Grant in 2016). They will establish experimental sites in each region to measure kelp growth and density under simulated harvesting conditions. Another experiment will determine rates of crab predation on sea urchins.

Elsewhere in the Northwest Atlantic, kelp forests are declining, possibly due to warmer temperatures and crowding from invasive non-native algal species  Also, harvesting of wild kelp has increased in Maine waters in recent years. Understanding differences in kelp productivity and susceptibility to harvest impacts will inform Maine’s seaweed industry and provide knowledge of the future of this important habitat.

Two-year project, 2018-2020
Sea Grant funds $149,980