Effect of Fluoxetine Hydrochloride on Routine Metabolism of Lambari (Deuterodon iguape, Eigenmann, 1907) and Phantom Shrimp (Palaemon pandaliformis, Stimpson, 1871)

HIGHLIGHTS Fluoxetine increases the metabolic rate and excretion of ammonia in both species. O:N ratio in fish showed higher values in the highest concentrations of fluoxetine. The LC50 - 96 hour values of Palaemon pandaliformis represented greater toxicity. Both species are a good biological model for fluoxetine exposure studies.

Abstract Fluoxetine is an emerging pollutant that acts as a selective serotonin reuptake inhibitor (SSRI) and being a hydrolytic molecule that is photolytically stable and accumulaties in biological tissues, its disposal in the aquatic environment can interfere with the physiology of fish and shrimp. Thus, the objective of this study was to analyze the effects of fluoxetine on routine metabolism (metabolic rate, specific ammonia excretion and O:N ratio) of Deuterodon iguape and Palaemon pandaliformis. For this, five groups of each species, were exposed to different concentrations of fluoxetine for 24 hours (D. iguape) and 2 hours (P. pandaliformis). The results demonstrated that in D. iguape exposure to fluoxetine significantly increased both the metabolic rate by 75%, 85%, 55% and 50% for concentrations of 0.05; 0.1; 0.5 and 1.0 mgL-1, respectively, and the specific ammonia excretion by 40%, 48% and 20% for concentrations of 0.05; 0.1 and 0.5 mgL-1, respectively, when compared with their control. The O:N ratio was statistically greater in concentrations of 0.5 and 1.0 mgL-1. Concerning P. pandaliformis, exposure to fluoxetine increased metabolic rate at concentrations 30.0 and 60.0 µgL-1, and also increased specific ammonia excretion at concentrations 10.0, 30.0 and 60.0 µgL-1, when compared with the control group. It was concluded that exposure to fluoxetine increases the routine metabolism of both species and that at the concentration 1.0 mgL-1, Deuterodon iguape required different energy substrates.

Seasonal variation in oxygen : nitrogen ratio of Soletellina diphos of Bhatye estuary, Ratnagiri coast, India.

In present investigation, oxygen consumption rate (OCR) and ammonia excretion rate (AER) of estuarine clam Soletellina diphos was estimated seasonally. The OCR in clams was higher in all size groups during winter season, while in summer lowest OCR was observed. Smaller clams consumed more oxygen than medium and large sized groups, respectively. AER was maximum during winter season, while minimum during summer season. The OCR and AER in small size clams were higher than medium and large sized clams. The maximum O: N ratio value (5.16) was observed in small size clams during summer followed by medium (3.27) and large size (2.66) clams, while minimum O:N ratio value was recorded in post-monsoon for small (3.23), medium (2.01) and large size (1.77) clams respectively. The smaller clams showed higher O:N ratio than medium and large size groups respectively. In present study, the O: N ratio was used as a tool to identify the stress or impact of seasonal variation on the natural population of clams from Bhatye estuary at Ratnagiri.