Watch the explanatory video about the project
Santiago de Compostela, Tuesday, 30 July 2024. The Spanish National Research Council (CSIC), through the Institute of Marine Research (IIM, Vigo), has completed the research carried out within the project “Ecology of the wild common octopus: resolving its ecological unknowns to achieve sustainable fisheries management and aquaculture (ECOSUMA)”. The work has revealed several previously unknown aspects of the ecology of the common octopus in the wild, especially of its paralarval and juvenile stages.
The project, launched in 2020, was led by EcoBioMar in collaboration with the Department of Ecology and Marine Resources of the IIM.
Fieldwork was carried out in Galician and northern Portuguese waters using data collected during a biological and oceanographic research campaign aboard the CSIC vessel Sarmiento de Gamboa, as well as underwater sampling. The team also used historical data from previous projects to study changes in paralarval abundance and associated climatic parameters in the study area, which includes campaigns carried out over the last 25 years near the Atlantic Islands of Galicia National Park (PNIAG).
“Ecological studies of paralarvae before their settlement on the seabed suggested that they were transported towards oceanic waters during their planktonic phase. The pre- and post-settlement phases, as well as the ecology of juveniles once they reach the fishing grounds near the coast, were practically unknown. That is why we investigated, among other aspects, trophic relationships, movements, growth and age during these phases in an area affected by seasonal upwelling, in order to move towards an ecosystem approach that supports the management of this socio-economically important resource,” explains Ángel González.
The research team identified 33 prey species exclusively in octopus paralarvae, corresponding to organisms present in zooplankton, including copepods, hyperiid amphipods, crab larvae, ostracods, pteropods, squid larvae, cnidarians, siphonophores and algae. Thirteen prey species were found exclusively in juveniles and corresponded to benthic organisms such as gammarid amphipods, hermit crabs, velvet crabs, fish, isopods, polychaetes and one nematode. Only two prey items were detected in both paralarvae and recently settled individuals.
Another achievement of the project was the creation of a biobank of mesozooplankton samples. A total of 1,700 samples from different oceanographic campaigns carried out by the EcoBioMar research group were traced, processed and stored, together with their associated metadata (50 parameters per sample). The collection also includes samples from other research centres, such as the IEO Vigo Oceanographic Centre, which has taken part in zooplankton monitoring programmes in Galician waters for decades.
“By counting growth rings in the beaks, we also estimated ages between 5 and 24 days for paralarvae, between 29 and 89 days for recently settled individuals weighing between 1 and 38 grams, and between 92 and 260 days for specimens weighing 104 to 460 grams in total,” says Ángel González.
To bring the main results of the project to a broad audience, the team carried out several outreach activities, including talks, scientific articles and videos such as the one describing the activities used to learn about adult movements through acoustic telemetry.
The research team has reported these and other findings in several papers published in high-impact academic journals, including Frontiers in Ecology and Environment, Ecology and Evolution and Animal Biotelemetry.