Acquisition of active acoustic data is the only synoptic approach to monitor the mesopelagic layer of the ocean which play a critical role both in the Earth carbon cycle and the functioning of marine ecosystem. Such technology is becoming mature and is still not enough deployed despite its high potential scientific value .

acoustic recording

snapshot of acoustic recording (probably a fish school interacting with a zooplankton layer) (UPMC/LOcean)

Several institutes from Australia and Europe collect acoustic data in the Southern Ocean and have developed first initiatives to integrate these key data in web databases (IMOS; SOOS; SONA). The IMOS public access acoustic database with associated documented processing routines and meta-data represents the underlying structure to build on for global accessible acoustic data for model uptake. The ICES WGFAST meta-data standard provides the framework for this data to be globally visible and useable. Based on these developments a common accepted international standard methodology needs to be progressed to combine and use these data in marine ecosystem models including micronekton functional groups.

These models are needed first to estimate the biomass and dynamics of these key components of the system, and then to provide the missing information for the understanding of predator behavior and ecology, analyzing the exploitation of marine resources, either being part of the micronekton (e.g krill, mesopelagic fish) or its predators (large fish), and projecting the impacts of climate change on the ecosystem and the carbon cycle.

New approaches in acoustic based on the use of multi-frequencies, and especially the new echo-sounder EK80 that are or will be installed on several EU and Australian Research Vessels, should help to discriminate the different groups of micronekton (e.g fish, krill, shrimps, jellyfish,…). Enhancement in the definition of micronekton groups and foodweb in the models need to be designed in close link with the information provided by these new tools.

See the MESOPP project report: