ST. PETERSBURG, FL - Marine organisms are affected by increasing temperatures and by declining oxygen and pH levels associated with changes in the global climate. Dr. Brad Seibel and fellow researchers seek to better understand how these changes affect unique as well as commercially important species in the oceans and to eventually map critical areas of depleted oxygen concentrations.
Squids are an interesting group of organisms in that they have extremely high metabolic requirements yet they are also incredibly sensitive to oxygen concentrations in the water column because their bodies are constrained in how they are able to utilize oxygen. They circumvent the issue by resting when at depth to decrease their metabolic rate.
Working especially with the jumbo squid (Dosidicus gigas), one of Dr. Seibel’s research projects follows changes in the distribution of this species due to climate effects on temperature, oxygen and pH. What regions of the ocean, as well as to what depth ranges these squids will migrate is of great interest.
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Dosidicus gigas swims in a flow tunnel. Credit: Stephani Gordon, Open Boat Films.
Another project focuses on zooplankton, small organisms near the base of the food chain that feed on phytoplankton and smaller zooplankton. These tiny organisms are more efficient than squid at extracting oxygen but also show signs of migration related to the changing climate, especially vertical migration in which they seek higher oxygen concentrations at shallower depths.
A third project looks at black sea bass, longfin squid and spiny dogfish sharks, three commercially important species in the northeastern U.S. Flow chambers allow researchers to measure metabolic rates while the organism is swimming against a current and while at rest in order to determine its total metabolic scope. An optimal aerobic scope exists at a certain temperature, above which activity, growth, and reproduction will suffer.
In addition to studying specific effects on organisms, Dr. Seibel and his group plan to map areas of low oxygen, called Oxygen Minimum Zones, which they have found to occur at finer spatial scales than was previously understood.