title: Combined Effects of Temperature and Seston Concentration on the Physiological Energetics of the Manila Clam Ruditapes philippinarum.
abstract: The suspension-feeding Manila clam Ruditapes philippinarum is a native species of the western Pacific that is now widely distributed around the globe because of its commercial importance. To determine the adaptive physiological responses to changing thermal and nutritional conditions, clearance, filtration, feces production, ammonium excretion, respiration rates, and scope for growth (SFG) were measured in adult clams. The clams were exposed to 24 treatments involving the combination of four water temperatures (8, 13, 18, and 23°C) and six concentrations of suspended particulate matter (SPM: 9.5 to 350.5 mg L(-1)). Physiological rates were standardized by using the mean (480 mg) of tissue dry weights of experimental clams using allometric equations between physiological variables and tissue dry weight. Higher clearance rates were recorded at higher temperatures and lower SPM concentrations, and these rates decreased with increasing SPM concentration at individual temperatures. Consumed energy increased with increasing temperature and SPM concentration, peaking at around 100-200 mg L(-1) at 18-23°C. Whereas fecal energy was largely determined by SPM concentration, ammonia excretion was mainly governed by temperature. Respiration rate studies revealed a predominant quadratic effect of temperature on the metabolism, indicating a lack of acclimatory adjustment of metabolic rate to rising temperature. SFG values were positive under almost all the treatment conditions and were much higher at higher SPM concentrations (> 45 mg L(-1)), with the highest level being recorded at 18°C and 100-200 mg L(-1) SPM. Increased filtration rate offset the increased metabolic cost at warm temperatures. Our holistic findings suggest that a high degree of physiological plasticity allows R. philippinarum to tolerate the wide range of temperatures and SPM concentrations that are found in tidal flats, accounting in part for the successful distribution of this species over a wide variety of geographical areas.
authors.affiliation: School of Environmental Science and Engineering, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea.
authors.forename: Hee Yoon
authors.initials: HY
authors.lastname: Kang
authors.affiliation: School of Environmental Science and Engineering, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea.
authors.forename: Young-Jae
authors.initials: YJ
authors.lastname: Lee
authors.affiliation: School of Marine Biomedical Science (BK 21 PLUS), Jeju National University, Jeju, Republic of Korea.
authors.forename: Kwang-Sik
authors.initials: KS
authors.lastname: Choi
authors.affiliation: Department of Marine Bioscience, Gangneung-Wonju National University, Gangneung, Republic of Korea.
authors.forename: Hyun Je
authors.initials: HJ
authors.lastname: Park
authors.affiliation: Department of Science Education, Daegu University, Gyeongsan, Republic of Korea.
authors.forename: Sung-Gyu
authors.initials: SG
authors.lastname: Yun
authors.affiliation: School of Environmental Science and Engineering, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea.
authors.forename: Chang-Keun
authors.initials: CK
authors.lastname: Kang
mesh_terms: D000818:Animals; D049872:Bivalvia / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D004734:Energy Metabolism / Q000187:drug effects; D052638:Particulate Matter / Q000032:analysis* / Q000494:pharmacology; D012044:Regression Analysis; D013696:Temperature
chemical_list: D052638:Particulate Matter