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Date Permissions Signed


Date of Award


Document Type

Masters Thesis

Degree Name

Master of Science (MS)


Environmental Sciences

First Advisor

Sulkin, Stephen D.

Second Advisor

Bingham, Brian L., 1960-

Third Advisor

Donovan, Deborah Anne, 1964-


The influence of acidification of the world's oceans on marine populations and communities is a subject of growing concern. In the case of crustaceans, issues such as calcium dynamics of the molting process and direct effects on survival and development rates of larvae have received, at most, limited attention. My thesis research looked at phenomena that are important in the success of larval crustacean stages, but have received no attention; namely, the effects of ocean acidification on the swimming speeds, feeding rate, and gross growth efficiency of stage one larvae of the Dungeness crab, Metacarcinus (Cancer) magister, and the Pacific Green Shore crab, Hemigrapsus oregonensis. For five days, the larvae of these crab species were held in carbon dioxide enriched seawater at the current atmospheric value for the control treatment (400 ppmv) and the projected level for the year 2100 (IPCC) for the high treatment (1000 ppmv). After Day 1 and Day 5, swimming behavior of the larvae was tested by looking at their distance travelled over time (orthokinesis) and the number of turns taken over time (klinokinesis). Their feeding rates were also compared by measuring the number of Artemia sp. nauplii consumed and gross growth efficiency was tested by measuring larval growth in calories divided by the total number of calories consumed. There was no significant difference found in swimming behavior, feeding rates or gross growth efficiency of either M. magister or H. oregonensis larvae between the CO2 treatments on each day. In both species, the swimming behavior and number of turns were higher on Day 1 when compared to Day 5. Results for the feeding rate showed an increase after five days for both species. However, after five days of exposure to acidified seawater, M. magister larvae had a significantly higher rate of turning than did those placed in the control CO2 conditions. This shows that high levels of ocean acidification may not directly affect feeding rates, the efficiency with which larval M. magister and H. oregonensis transform energy consumed into growth or the total distances travelled per unit time,. But, it may have an effect on larval movement patterns which may in turn affect larval vertical distribution and dispersal.





Western Washington University

OCLC Number


Subject – LCSH

Crabs--Larvae--Effect of water acidification on--Washington (State); Crabs--Larvae--Nutrition--Washington (State); Crabs--Larvae--Behavior--Washington (State); Crabs--Larvae--Washington (State)--Growth

Geographic Coverage

Washington (State)




masters theses




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