Sometime in the 1980’s and 1990’s the sea otters throughout the Aleutian Islands, Alaska began to disappear, causing their favorite food (green sea urchins) to explode in numbers. As this continued over the following decades, the sea urchin numbers became so great that they began to eat up all the kelp and associated algae, leaving behind urchin barren grounds (areas devoid of most seaweeds but with lots and lots of sea urchins). This also resulted in apparent changes in a host of associated invertebrates and fishes, such that now much of the Aleutian Islands have dramatically changed and no longer reflect the old dense kelp forest ecosystems. This begged the questions; what does this change mean to patterns of biodiversity? And what does this mean for the whole Aleutian Islands ecosystem’s primary production?
Our trip is being led by Drs. Matthew Edwards from San Diego State University and Brenda Konar from the University of Alaska Fairbanks. Drs. Edwards and Konar have both worked together in this ecosystem over the past few decades, beginning when they were graduate students in Dr. James Estes’ lab at the University of California Santa Cruz. Dr. Estes is the first to have described these changes and the causes of them, earning his induction into the National Academy of Sciences. Now, Drs. Edwards and Konar are following the work of Estes and trying to learn what these changes mean to the way the ecosystem functions.
On this research trip to the Aleutians, which has been funded buy the National Science Foundation, we are looking specifically at how patterns of biodiversity compare between kelp forests, urchin barren grounds, and areas in transition between these two states. Our work is primarily done on SCUBA (using dry suits of course), but there are activities involving benthic trawls to look at deeper habitats beyond the reach of traditional SCUBA to understand how the loss of kelp subsidies (i.e. drifting detached kelp) is impacting these habitats. In the shallower waters (20-40’) our group is dividing our efforts into two main categories. The Konar lab from UAF will be surveying the bottom and counting seaweeds and invertebrates, and collecting samples of each to get a measure of their biomass in each habitat. The Edwards lab from SDSU will be deploying benthic chambers to measure ecosystem production. These chambers are specially designed and equipped with Oxygen, light and temperature sensors to measure photosynthesis and respiration in each habitat. Also, we have along with us Dr. Ju-Houng Kim from (Chonam National University) in Korea who is working on the ship to measure how each individual species contributes to the overall patterns we are seeing. He has brought with him special equipment that measures photosynthesis and respiration for each species, and this information can be evaluated against what the Konar and Edwards labs are doing.
Check in with us from time to time over the next two weeks to follow our progress.