Effects of temperature on caffeine and carbon nanotubes co-exposure in Ruditapes philippinarum

In the marine environment, organisms are exposed to a high and increasing number of different contaminants that can interact among them. In addition, abiotic factors can change the dynamics between contaminants and organisms, thus increasing or even decreasing the toxic effect of a particular compound. In this study, the effects of caffeine (CAF) and functionalized multi-walled carbon nanotubes (f-MWCNTs) induced in the clam Ruditapes philippinarum were evaluated, acting alone and in combination (MIX), under two temperature levels (18 and 21 degrees C). To assess the impact of such compounds, their interaction and the possible influence of temperature, biochemical and histopathological markers were investigated. The effects of f-MWCNTs and caffeine appear to be clearly negative at the control temperature, with lower protein content in contaminated clams and a significant decrease in their metabolism when both pollutants were acting in combination. Also, at control temperature, clams exposed to pollutants showed increased antioxidant capacity, especially when caffeine was acting alone, although cellular damages were still observed at CAF and f-MWCNTs treatments. Increased biotransformation capacity at 18 degrees C and MIX treatment may explain lower caffeine concentration observed. At increased temperature differences among treatments were not so evident as at 18 degrees C, with a similar biological pattern among contaminated and control clams. Higher caffeine accumulation at MIX treatment under warming conditions may result from clams' inefficient biotransformation capacity when exposed to increased temperatures. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

In this study, the effects of caffeine and functionalized multi-walled carbon nanotubes on clams were evaluated at different temperature levels. The results showed negative impact of these compounds at the control temperature, with a decrease in protein content and metabolism. The biotransformation capacity at 18 degrees Celsius may explain the lower caffeine concentration observed and differences among treatments were less evident at the increased temperature level.