Meeting Abstract

P2-144  Saturday, Jan. 5 15:30 – 17:30  Response of zooplankton to a phytoplankton bloom in coastal waters of the Western Arabian Gulf CLARDY, TR*; HEINLE, MJ; THOMAS, BK; AL-NUWAIRAH, MA; DAS, PB; QURBAN, MA; HIKMAWAN, TI; PRIHARTATO, PK; ABDULKADER, KA; King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia; King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia; King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia; King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia; King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia; King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia; Environmental Protection Department, Saudi Aramco, Dhahran, Saudi Arabia; Environmental Protection Department, Saudi Aramco, Dhahran, Saudi Arabia; Environmental Protection Department, Saudi Aramco, Dhahran, Saudi Arabia tclardy@kfupm.edu.sa

Phytoplankton blooms can have significant positive or negative effects on the structure and abundance of zooplankton communities. A diatom bloom comprised of Skeletonema sp. and Thalassiosira sp. was encountered off Khobar, Saudi Arabia. A suite of environmental and biological parameters within the bloom and at a reference site were measured to assess the effect of the bloom on zooplankton. The dominant copepod species at both sites, Acartia ohtsukai, showed a 15x reduction inside the bloom. The fitness of individual A. ohtsukai inside and outside the bloom was compared using body volume. Measurements of the prosome and urosome from 50 males and 50 females from each location were made to calculate the body volume of individual copepods. There were no significant differences in copepod volume between sites for either sex, indicating the bloom was not affecting the fitness of individual copepods. Both Skeletonema and Thalassiosira produce aldehydes that compromise embryonic development in copepod eggs. The reduction in zooplankton density associated with the bloom was likely a result of population-level effects on reproduction rather than a reduction in individual fitness.