Bathyal feasting: post-spawning squid as a source of carbon for deep-sea benthic communities

Area of Science:

• Marine Biology
• Deep-Sea Ecology
• Oceanography

Background:

• Oceanic carbon budgets show a gap between deep-sea ecosystem energy needs and organic matter supply.
• This discrepancy suggests unmeasured food sources reaching the seafloor.
• Squid populations are vast and expanding, potentially increasing their role in marine food webs.

Purpose of the Study:

• To investigate the role of squid carcasses as a food source for deep-sea benthic communities.
• To quantify the carbon contribution of squid falls to the seafloor in the Gulf of California.

Main Methods:

• Remotely operated vehicle (ROV) surveys were conducted in the Gulf of California.
• Observations of squid carcasses and egg sheets were recorded, along with associated scavenger species.
• Carbon deposition rates were estimated based on observed food fall events.

Main Results:

• 64 post-brooding squid carcasses and egg sheets were documented across 11 ROV dives.
• Various deep-sea scavengers, including Ophiuroidea, Holothuroidea, Decapoda, Asteroidea, and Enteropneusta, were observed feeding on the remains.
• Estimated annual squid carcass deposition rates ranged from 0.05 to 12.07 mg C m⁻² d⁻¹ in observed areas.

Conclusions:

• Sinking squid carcasses are a significant, yet underestimated, carbon vector to the deep seafloor.
• This phenomenon plays a crucial role in supporting deep-sea scavenger communities.
• Further research with standardized methods in squid-rich regions is needed to assess the global impact of squid falls on carbon budgets.