The aim of this research, which involved institutions from Europe, Africa and the Americas, was to assess how conservation measures influence the body size of this marine gastropod in the face of exploitation and specific local conditions
However, the results show that, although protected areas tend to harbour larger individuals, responses vary according to species, ecological context and local processes, which prove to be more decisive factors than the differences between the various regions studied
In the Canary Islands, reductions in the size of some species were detected over time, associated with exploitation pressure. The results highlight the importance of adapting management strategies to each species and location, both within the archipelago and on a global scale, by strengthening monitoring and taking into account factors such as recruitment and environmental conditions
The ECOAQUA University Institute at the University of Las Palmas de Gran Canaria (ULPGC), through its Biodiversity and Conservation (BIOCON) group, has taken part in an international research project that analysed 95,809 specimens of limpets from 12 species belonging to three genera (Cymbula, Patella and Scutellastra). The aim of this study, which involved universities, research centres and institutions from Spain, Portugal, South Africa and Mexico, was to determine how marine protection, habitat characteristics and local factors influence the size structure of limpet populations on a global scale.
However, the study’s results show that there is no single response to marine protection. Although limpets are generally larger in protected no-take zones, the differences depend on the species, the type of habitat and local processes, which prove to be more decisive than differences between regions. This is a key finding that will be of great use in redesigning protection strategies in the future.
Therefore, according to this research, the effective conservation of these intertidal communities requires site-specific strategies that integrate protection measures with local habitat conditions and the capacity to enforce conservation regulations.
File photo of black and white limpets collected for study in the intertidal zone.
The study, entitled ‘Global drivers of size variation in patellid limpets and their implications for marine protection and conservation outcomes’, has recently been published in the prestigious scientific journal ‘Global Ecology and Conservation’ (GECCO).
Of the eleven researchers who participated in this study, two are from the ECOAQUA University Institute at the ULPGC: Dr Joana Vasconcelos and Professor Rodrigo Riera, whose work has been crucial in data analysis, scientific coordination and the interpretation of results, making a key contribution to the development of the research and the drafting of the scientific paper.
The geographical scope of the study covered areas such as Madeira (Portugal), the Canary Islands (Spain), the western Mediterranean and the Strait of Gibraltar (Alborán Island, Ceuta, La Línea), the Pacific coast of Mexico (Jalisco and Nayarit) and South Africa (the southern Benguela and Agulhas bioregions).
Results in the Canary Islands
According to Rodrigo Riera, “in the Canary Islands, reductions in the size of some species have been observed over time, linked to fishing pressure”. The results highlight the importance, he says, of “tailoring management strategies to each species and location, stepping up monitoring and taking into account factors such as recruitment and environmental conditions”.
Map of the areas where the international study was conducted.
The average shell lengths of the species Patella aspera (white limpet) and Patella candei (Majorera limpet) were consistently below their respective size thresholds at 50% maturity. In Fuerteventura, specimens of Patella candei, listed in the national catalogue of endangered species, were significantly larger than those of Patella crenata (black limpet) from Tenerife. These taxa represent different sister lineages found on different islands, and the comparison highlights differences in shell size between islands within the candei–crenata complex.
Key intertidal herbivores for algae
Coastal ecosystems harbour great biodiversity and provide essential habitats for marine organisms. Limpets are key intertidal herbivores that regulate seaweed dynamics, and their population structure is highly sensitive to harvesting pressure, habitat characteristics and local environmental conditions, making them useful indicators of human impact and management effectiveness.
To conduct the research, an interregional and multi-oceanic comparison of the shell length of limpets was carried out to assess how size distributions are influenced by protection status (banned from capture versus harvested), substrate type and spatial scale.
The data revealed an overall positive effect of protection, with significantly larger individuals in closed areas across the global model, although responses varied between species and regions.
Most of the variability in size occurred between different sites rather than between regions, highlighting the dominant role played by small-scale environmental conditions, harvest intensity and the effectiveness of regulatory enforcement in determining population size structure.
In addition to ECOAQUA’s BIOCON group, the following organisations participated in the study: the Marine Biology Laboratory of the Department of Zoology, Faculty of Biology, University of Seville (Spain); MARE – Marine and Environmental Sciences Centre / ARNET - Aquatic Research Network, Regional Agency for the Development of Research, Technology and Innovation (ARDITI), in Madeira (Portugal); the Directorate of Marine Monitoring, Studies and Research Services, Regional Directorate for the Sea, Funchal Fish Market, in Madeira (Portugal); the Institute of Marine Sciences and Limnology at the National Autonomous University of Mexico, in Mazatlán, Sinaloa (Mexico); the Department of Studies for the Sustainable Development of Coastal Areas, CUCSUS, at the University of Guadalajara, in Jalisco (Mexico); and the Department of Biological Sciences and Marine Research Institute at the University of Cape Town, Rondebosch (South Africa).