Periodic Reporting for period 2 - SUMMER (Sustainable management of mesopelagic resources)
Okres sprawozdawczy: 2021-03-01 do 2022-08-31
With a potential biomass of mesopelagic fish of 10 times more than all other fish together, we have to evaluate whether and how mesopelagic resources can be exploited without compromising the essential ecosystem services they provide. As the mesopelagic is among the last untouched ecosystems of the planet, this is the last chance and first time to do things in the right way, i.e. to first obtain scientifically sound data, create models and exploitation scenarios and only then - if regarded possible from an ecological and economic point of view - exploit in a sustainable manner.
In terms of the carbon transport, we highlight how little is known about the physiological ecology of mesopelagic fish, trophic pathways within the mesopelagic food web, and how these link to primary production in the surface ocean. However, in order to understand the main uncertainties SUMMER has developed and online tool (SUMMER fish estimator (shinyapps.io)) to assess the impact of the main factors influencing the total fish biomass. Regarding these active fluxes and based on a end to end model, it has been obtained how that migratory mesopelagic fish are responsible for export of about 1.39 PgC y-1, which represents about 9-28% of the total export of carbon to the twilight zone.
Regarding the potential availability of the Ocean Twilight Zone (OTZ) as a source of PUFA (e.g Omega-3) novel insights into the identity and biogeography of potential microbial omega-3 producers has been developed based on metagenomic data mining . However, the exact products of the putative omega-3 biosynthetic gene clusters identified remain unknown and should be assessed further to verify their ability to produce these fatty acids. Also, most of the identified candidates remain uncultured, which implies that this is not a short-term route to obtain microbial PUFA suppliers. With all the available information an economic analysis of it is worth to exploit or not the OTZ has been performed. Result is clearly driven by the uncertainty, in terms of the ecological effects on other species, carbon sequestration and provisioning of fishmeal and fish oil, and even further on the economic parameters of the evaluation (i.e. prices of all these ecosystem services). Nevertheless, results suggest that currently the nonexploitation or low exploitation rates are preferred than a generalized commercial exploitation. An online tool to analyse different exploitation rates of mesopelagic fish has been developed (in this reporting period) and will be delivered in the next reporting period
Within this period SUMMER partners have published 26 peer-reviewed articles and 7 are under review. 21 data resources were published in open access in RP2, including georeferenced data archived at PANGAEA, genetic resources published via GenBank’s Short Read Archive, and data and code deposited at GitHub with DOI registration at Zenodo. SUMMER datasets at PANGAEA are now also findable through the Group of Earth Observations System of System (GEOSS) Portal hosted by the European Space Agency (ESA).
So far, it has been obtained new insight in terms of biodiversity of this sea layer, carbon fluxes and therefore the role of the OTZ in the carbon sequestration, and specifically of the diel vertical migration of mesopelagic fishes. Based on these results, a tradeoff analysis of the ecosystem services currently provided by the mesopelagic layer and their potential under exploitation has been performed. SUMMER has also tested and validated methods to estimate abundance of biomasses of mesopelagic fishes. Based on that the two main objectives of SUMMER are on track: How to estimate biomass and answer the question of fishing them or not, from the social perspective. It is acknowledged, that results are still under big uncertainties, but SUMMER is on track to reduce them in the next reporting period.