Kelps in Hot Water: How are seaweeds responding to a rapidly warming Gulf of Maine?

Submitted by Rachel Lasley-Rasher on Tue, 08/23/2016 - 23:16

NOTE: This blog was written by Thew Suskiewicz, a graduate student at Université Laval in Quebec working on a Sea Grant funded project with Dr. Robert Steneck 

These are dynamic times for the Gulf of Maine. Over the past decade, water temperatures here have risen faster than almost anywhere on the planet, and already fishermen and researchers are noticing drastic changes along our coast. Lobsters have been shedding up to six weeks earlier than average, Jonah crab landings have been steadily increasing, and areas once barren of fleshy seaweeds are now covered.

In 2004, I was working as a scientific technician for Dr. Bob Steneck at the University of Maine’s Darling Marine Center. We spent five months surveying more than 100 sites along the coast of Maine, from New Hampshire to the Canadian boarder. We found that seaweeds were more abundant in the western part of the state, and relatively rare east of Mount Desert Island. These patterns broadly reflected the distribution and history of urchin harvesting in the state: areas in western Maine had higher urchin harvesting during the 1990s and had more kelp in 2004, areas in the Down East region had less urchin harvesting in the 1990s and had less kelp in 2004. Now, with support from Maine’s Sea Grant program, we are revisiting more than a dozen of these sites, many of which haven’t been sampled since 2004.

Despite their ecological importance and proximity to Maine’s Highway 1, we know very little about the seaweed communities just offshore. Similar to how a hardwood forest and a grassy meadow support different animal communities on land, we know that different seaweed communities will do the same in the ocean. This project seeks to examine those seaweed communities, quantify the crabs and lobsters living there and compare what we see in 2016 to what we saw in 2004.

One of the biggest differences between 2016 and 2004 is the technology available to us. A decade ago, underwater digital cameras were expensive, bulky and lacked video capabilities. Today’s cameras are so much smaller and less expensive that we frequently take multiple cameras with us on a dive. Using open-source software we’re now able to take video files and create large scale photo-mosaics, which are essentially 100MP photos of the ocean floor created from thousands of overlapping video frames. These photo-mosaic files provide us with a permanent record we can reference in the future to detect changes, and allow us to address questions about the distribution of seaweeds and the species present in a way that we never could before.

I left Maine to pursue my Masters Degree in 2006, and what’s surprised me the most is just how fast the Gulf of Maine has changed in a single decade, even in the areas where we weren’t expecting to see large changes. So far we’ve sampled the Pemaquid and western Penobscot bay regions, and we’re seeing not only more seaweed, but also more species of seaweed.