The study, carried out by the BIOCON group at the ULPGC institute at 15 coastal stations in Sweden, collecting more than 18,000 individuals from 37 taxonomic groups living among the roots of Zostera marina, would, if applied in the Canary Islands, enable more sustainable management and strengthen the conservation of the seagrass beds of the popular seba (Cymodocea nodosa), known as sebadales, whose reduction in recent decades is estimated at between 30% and 50% due to factors such as pollution, invasive species and coastal construction.
Seagrass beds are one of the most productive and valuable ecosystems on the planet, but also one of the most threatened by human activity. A new international study led by Professor Rodrigo Riera, from the Biodiversity and Conservation (BIOCON) group at the ECOAQUA University Institute, part of the University of Las Palmas de Gran Canaria (ULPGC), proposes a more comprehensive way of strengthening their conservation and assessing their ecological status: including the analysis of infauna, the organisms that inhabit the sediment.
In this way, ECOAQUA, through BIOCON, consolidates its role and that of the ULPGC as international leaders in benthic ecology and marine ecosystem management, offering a new scientific tool to advance towards more sustainable management of underwater habitats, both in the Atlantic and in northern Europe.
Under the title “Towards a more comprehensive environmental assessment: using infauna to conserve and manage Zostera marina beds”, the research, which was recently published in the prestigious scientific journal “PLOS One”, was conducted on the west coast of Sweden (Skagerrak), where the seagrass beds of the aquatic plant Zostera marina - which in Spain can be found in the Cantabrian Sea and in areas of the Atlantic Ocean - have been in decline for decades due to human impact and environmental changes.
Although epifaunal communities, those that live on the surface of the seabed sediment, have been studied extensively, infaunal communities, which live among the sediment particles in the marine environment, have been little explored to date.
This study, carried out in collaboration with the Department of Biological and Environmental Sciences at the University of Gothenburg (Sweden) and the Water Research Institute (IRSA) of the Italian National Research Council (CNR), analyses their spatial variability at 15 coastal stations, collecting more than 18,000 individuals from 37 different groups, from polychaetes and molluscs to chironomids and oligochaetes. The results showed that the biomass of Zostera marina and exposure to waves are determining factors in the structure of these communities.
Split underwater image by researcher Eduardo Infantes showing the Zostera marina bed located in front of the Kristineberg research station in Sweden, University of Gothenburg. Image obtained from https://www.eduardoinfantes.com/seagrass-lab/
Overall, the study provides a useful scientific basis for the management and conservation of seagrass beds, highlighting the value of infauna as a complementary ecological indicator.
This research is one of the first to use infaunal communities as a tool to assess the ecological status of Zostera marina beds on the Swedish coast, providing, according to Riera, a ‘more comprehensive and integrated view by combining information on infauna, epifauna and environmental factors, something that was unusual in previous studies’.
The results show that infaunal communities respond differently to epifaunal communities, providing valuable information on the ecological status and regression of these beds, so including both groups will improve the accuracy of ecological assessments. ‘This opens the door to improving the ecological diagnostic tools we use in coastal ecosystems,’ says Professor Riera.
Applications for seagrass beds in the Canary Islands
Although the study was conducted in Sweden, its results are directly relevant to the Canary Islands, as seagrass beds—especially those formed by the popular seagrass (Cymodocea nodosa), known as seagrass beds—perform ecological functions similar to those of Swedish Zostera marina: they provide habitat, food and shelter for numerous marine species, as well as protecting the coastline and storing carbon.
In the Canary Islands, seagrass beds or Cymodocea nodosa have suffered an estimated reduction of between 30% and 50% in recent decades due to human pressures such as pollution, anchoring, coastal construction and increased water turbidity.
Image of seagrass beds in Guguy, Gran Canaria.
According to Professor Rodrigo Riera, who, together with Joana Vasconcelos and Eduardo Infantes, also from the BIOCON group, and two other researchers, carried out this research, the results obtained in Sweden could be applied in the archipelago to "use infauna as a bioindicator of the ecological status of Canarian meadows, complementing studies based on epifauna or physical and chemical parameters, as well as developing more comprehensive environmental assessments that include both taxonomic and functional diversity, improving monitoring and conservation programmes.
In addition, he says, it would allow ‘the identification of areas with greater degradation or exposure to human impacts, helping to prioritise restoration and management actions’.
In summary, Riera points out that applying this approach in the Canary Islands ‘would reinforce the conservation of Cymodocea nodosa seagrass beds and improve the assessment of coastal ecological status through more comprehensive and sensitive biological methods’.
‘Integrating biological information from all levels of the ecosystem will allow us to monitor the effects of climate change and human pressures more reliably,’ he concludes.
On the other hand, returning to Sweden, the biotic indices applied (such as AMBI, M-AMBI and BQI) revealed that most of the meadows are in a moderately altered state, although with clear differences between areas. Areas with higher vegetation density, such as Skalhavet and Lindholmen, were in better ecological condition than more degraded areas, such as Finsbo and Kvarnekilen.
The study was funded by the Royal Swedish Academy of Sciences (KVA), through grants to the Kristineberg Centre for Marine Research and Innovation and the University of Gothenburg (Sweden); the Fundação para a Ciência e a Tecnologia (FCT) in Portugal, through various research projects and institutional support (references: SFRH/BSAB/143056/2018, UIDB/04292/2020, UIDP/04292/2020 and LA/P/0069/2020). In addition, researcher Joana Vasconcelos received support from the Viera y Clavijo Training Programme for Researchers of the Government of the Canary Islands (call VIERA Y CLAVIJO-2022-CIENCIAS-1).