Predation risk increases in estuarine bivalves stressed by low salinity

Area of Science:

• Marine Ecology
• Environmental Science
• Aquaculture

Background:

• Estuarine salinity is decreasing due to increased heavy rainfall frequency and intensity.
• This environmental change poses physiological and ecological risks to marine organisms.
• Bivalves are crucial commercial species in European estuaries.

Purpose of the Study:

• To investigate the impact of low salinity stress on the predation risk of three key European bivalve species.
• To compare the predatory behavior of native and non-indigenous predators on stressed bivalves.
• To understand how altered salinity affects bivalve population dynamics through predator-prey interactions.

Main Methods:

• Laboratory experiments exposing juvenile bivalves (Venerupis corrugata, Cerastoderma edule, Ruditapes philippinarum) to low salinities (5, 10, 35) for two days.
• Choice experiments presenting bivalves to common predators: Carcinus maenas (shore crab) and Bolinus brandaris (gastropod).
• Measurement of predator consumption rates and predatory behavior (handling time, rejections, consumption rate).

Main Results:

• Both predators consumed significantly more low-salinity stressed bivalves than non-stressed ones.
• Bolinus brandaris exhibited more generalist predatory behavior than Carcinus maenas.
• Native bivalves (C. edule, V. corrugata) were consumed more than the introduced R. philippinarum, likely due to salinity vulnerability and physical traits.

Conclusions:

• Low salinity stress increases bivalve vulnerability to predation by both native and non-indigenous predators.
• Changes in estuarine salinity due to increased precipitation can significantly alter predator-prey dynamics.
• These shifts in bivalve-predator interactions have implications for the population dynamics and management of commercially harvested shellfish.