The effects of polycyclic aromatic hydrocarbons and crude oil exposure on thermal tolerance of larval and juvenile lumpfish (Cyclopterus lumpus)

Abstract

Polycyclic aromatic hydrocarbons (PAH) in crude oil can impair fish heart function. Since the heart helps sustain increasing energy demand during warming, PAH-induced cardiac perturbations could impair warming tolerance. I investigated how acute (24 hr) sublethal PAH exposure (methylnaphthalene, naphthalene, phenanthrene) affects tolerance to acute warming in larval and juvenile lumpfish (Cyclopterus lumpus), a widespread cold-water fish. I measured critical thermal maximum (CTmax) in larvae, and maximum heart rate (fHmax) and cardiac thermal tolerance metrics in juveniles. Cardiac thermal tolerance of juveniles was resistant to relevant levels of naphthalene and phenanthrene (and crude oil), whereas higher methylnaphthalene concentrations reduced the temperatures of peak fHmax and cardiac arrhythmia. Surprisingly, higher phenanthrene concentration increased larval CTmax. While lumpfish thermal tolerance was relatively resistant to PAHs, higher PAH exposures increased moribundity of both life stages. My findings help us understand how lumpfish may respond to oil exposure and warming in a changing climate.