The oceans’ twilight zone must be studied now, before it is too late

Abstract

he twilight zone contains the largest and least exploited fish stocks of the world's oceans. Spanning from just below 200 metres to 1,000 metres deep, it is an interface between the well-studied marine life in the sunlit zone above and the ecosystems of the abyss below. It has a major role in removing carbon dioxide from the atmosphere and storing it for centuries or longer. The twilight zone is also privy to the largest migration on Earth. Huge numbers of fishes and zooplankton move hundreds of metres towards the surface each night to feed, before retreating back down at dawn. Yet the zone is poorly understood-physically, biogeochemically and ecologically. Exploitation and degradation of the mysterious layer between the sunlit ocean surface and the abyss jeopardize fish stocks and the climate. The elongated bristlemouth (Sigmops elongatus) is abundant in the oceans' twilight zone.

Advancing Global Ecological Modeling Capabilities to Simulate Future Trajectories of Change in Marine Ecosystems

“…However, a slight decline is observed under IPSL CMA5-LR RCP8.5 scenario. These results are relevant in the light of their important biomass and key role in supporting the marine ecosystems (Irigoien et al, 2014) and the current discussion about their potential for exploitation vs. sensitivity to cumulative impacts (Hidalgo and Browman, 2019;Martin et al, 2020). Figure 14) compared to the climate impact simulations (Figure 9).…”

“…Our modeling complex indirectly represents the third dimension of depth by vertically stratifying species groupings, their interactions, and the flows of energy and matter. However, the vertical use of the water column may be altered by climate change and future exploitation (Brito-Morales et al, 2020;Jorda et al, 2020;Martin et al, 2020). As new insights into these still underexplored deep-sea habitats become available, future iterations of our work may have to revisit the representation of processes that take place in the water column.…”

Remote assessment of the fate of phytoplankton in the Southern Ocean sea-ice zone

“…In comparison, other estimates of net community production based on export or nitrate drawdown relative to winter 27 , are on a seasonal to annual time scale. Some of the most recent BGC-Argo floats are equipped with Underwater Vision Profilers (UVP6) which will allow counting organisms from bacteria to zooplankton 52 . The ability to discern the fate of SIZ phytoplankton is essential for understanding the current magnitude of, and future trends in the highlatitude biological pump and ecosystems.…”

Marine wild-capture fisheries after nuclear war

“…The total biomass of all fish species is highly uncertain (69), meaning that this potential is poorly known, but the biomass of unexploited mesopelagic fishes is believed to be larger than the total global biomass of currently exploited wild finfish (70). If a global food crisis would induce the rapid development of more effective harvesting technologies for these dispersed fish and other currently unexploited species, fisheries could further mitigate terrestrial crop failures, but with potentially large and poorly understood consequences for marine ecosystems (71,72).…”