Ocean acidification alters temperature and salinity preferences in larval fish

Area of Science:

• Marine Biology
• Chemical Oceanography
• Ecology

Background:

• Ocean acidification (OA) affects marine animal senses like audition, olfaction, vision, and pH sensing.
• Little is known about how OA impacts other senses crucial for marine species' survival and dispersal.
• Marine and estuarine species rely on physicochemical cues for habitat detection and settlement.

Purpose of the Study:

• To investigate if ocean acidification alters larval fish preference for physicochemical cues used in dispersal between ocean and estuarine environments.
• To experimentally assess the behavioral response of larval fish (Lates calcarifer) to elevated temperature, reduced salinity, and estuarine water cues under acidified conditions.
• To determine the impact of elevated CO2 concentrations on the perception and evaluation of environmental cues during fish dispersal.

Main Methods:

• Experimental assessment of larval fish (Lates calcarifer) behavior.
• Exposure of larvae to elevated CO2 concentrations simulating future ocean acidification scenarios.
• Testing behavioral responses to manipulated water conditions: elevated temperature, reduced salinity, and natural estuarine water with olfactory cues.

Main Results:

• Larvae raised under elevated CO2 showed attraction to warmer water, a response absent in larvae under contemporary CO2 levels.
• Larvae under contemporary CO2 were deterred by lower salinity water, but CO2-treated larvae showed no such response.
• Only CO2-treated larvae preferred natural estuarine water (warmer, lower salinity, with olfactory cues), indicating altered sensory perception.

Conclusions:

• Ocean acidification significantly alters larval fish attraction to key physicochemical cues, affecting their dispersal and habitat selection.
• Altered perception of environmental cues due to OA can have profound implications for fish recruitment and population replenishment.
• The study highlights that OA impacts not only marine species but also freshwater species with marine life stages, negating behavioral responses to crucial environmental cues.