Bioenergetic responses of Gammarus salinus and Mytilus edulis to oil and oil dispersants in a model ecosystem

Abstract

As part of a multifaceted study to assess the impact of oil and oil dispersants on a model littoral ecosystem in the Baltic Sea, bioenergetic (O:N ratio) measurements were made for 2 of the predominant species, the mussel M. edulis and the amphipod G. salinus. In addition, ammonia excretion and respiration rate measurements for G. salinus and byssal thread production rates and spawning frequency observations for M. edulis were made. Four days after the start of the exposure, significant effects on byssal thread production rates and spawning frequency were observed for the oil/dispersant treatment. After 12 d [days] the oil/dispersant group apparently had recovered; the oil-only group was exhibiting abnormal spawning behavior. No effects on ammonia excretion rates, respiration rates or O:N rates were observed after 1 d for G. salinus. After 10 d, highly significant differences were recorded between experimental groups and controls for all 3 parameters. While both oil and oil/dispersant treatments produced subtle physiological alterations in the animals investigated, the use of a chemical dispersant apparently resulted in a more rapid recovery of the species investigated than would have occurred if the oil had not been chemically dispersed.