The mesopelagic communities (macro-zooplankton and micronekton communities ~2 to 20 cm in length including small fish, crustaceans, squids and gelatinous organisms) living in the twilight zone of the ocean have been identified as one of the least investigated components of open ocean ecosystems. Mesopelagic communities are mid-water prey at 200–1000 m depth and based on their biomass, make the largest daily animal movement on earth. They transfer energy from primary producers to higher predators, and actively transport carbon from the surface waters to the deep-ocean by linking epipelagic and deep-water food chains. Knowledge of the structure and function of biota in the deep ocean is necessary to assist in managing human impacts, and especially to predict the behaviour of oceans in a changing climate using ecosystem models. Ecosystem models need observations on the distribution and abundance of mesopelagic functional groups at shelf and basin scale to validate predictions.

Vessels of opportunity programs collect underway active bioacoustic data while transiting ocean basins. These acoustic snapshots provide an indicator of abundance, distribution, and behaviour of mesopelagic communities. Thus improving the measurement situation with several major international efforts to sample the world’s oceans. The mapping complement established observing systems measuring physical, chemical, and biological environment of the ocean. This will help to advance scientific knowledge of marine food chains and manage marine ecosystems sustainably.

MESOPP report on Acoustic data from vessels of opportunity provides ecosystem modellers with a brief overview of:

  • Variables contained in the processed acoustic data to assist interpretation of bioacoustic data.
  • Bioacoustic metrics used in literature to study mesopelagic zone.
  • Effects of data processing routines on the metrics derived for the use in ecosystem models.
  • Potential limitations of the data for uptake in ecosystem models.

(A previous deliverable in the MESOPP project explained the acoustic data processing routines and quality checking methods)

See the reports in the Scientific articles & contributions page.