Global decline of pelagic fauna in a warmer ocean

Abstract

Pelagic fauna is expected to be impacted under climate change according to ecosystem simulations. However, the direction and magnitude of the impact is still uncertain and still not corroborated by observational-based statistical studies. Here we compile a global underwater sonar database and 20 ocean climate projections to predict the future distribution of sound-scattering fauna around the world's oceans. We show that global pelagic fauna will be seriously compromised by the end of the 21 st century, if we continue under the current greenhouse emission scenario. Low and mid latitudes are expected to lose from 3 to 22% of animal biomass due to the expansion of low-productive systems, while higher latitudes would be populated by present-day temperate fauna, supporting conclusions drawn from ecosystem simulations. We further show that strong-mitigation measures to contain global warming below 2°C would reduce these impacts to less than half.

A shallow scattering layer structures the energy seascape of an open ocean predator

“…Given burgeoning interest in scattering layer fisheries ( 66 ), predictions for climate change to cause a global decline of scattering layer fauna ( 67 ), and scattering layer research being predominantly focused on the globally distributed primary DSL ( 16 , 17 ), increased effort is needed to understand the ecology and biogeography of the SSL in the mid-latitudes. The occurrence of an SSL in multiple subtropical gyres ( 20 , 40 ), the oligotrophic Red Sea ( 68 ), and elsewhere under specific oligotrophic conditions ( 19 ), merits investigation to determine whether high light penetration driving the DSL(s) deeper increases ecological niche availability via vertical segregation.…”