Shellfishers’ Knowledge in Western Iberia: The Case Study of Edible Cockle (Cerastoderma Edule) In the Ria de Aveiro Lagoon

BackgroundCockles are an essential biological resource for several fishing villages in Europe, especially in Portugal. This bivalve is highly commercialized in the Aveiro coastal lagoon and has relevant socio-economic importance for local shellfishers. In the absence of a management plan, indications for carrying out new ecological studies on the cockle, and all the aggregated history of this natural resource in the Ria de Aveiro, sharing the ethnobiological knowledge of shellfishers becomes relevant in this scenario. We shared the highlights of local ecological knowledge (LEK) about the cockle (C. edule) in the Ria de Aveiro in favor of the adaptive management of this bioresource. MethodsRia de Aveiro is an ecologically prominent area in Europe due to its faunal biodiversity. Semi-structured interviews with sixty shellfishers in this coastal lagoon were carried out during April and May 2021. LEK data on the biology and ecology of the cockle (C. edule) were analyzed using an ethical-emic approach and the model of integration of different individual skills. These informal data were compared with previously published data for the species, the Fish Base, and GBIF databases. Interviews were categorized and analyzed using the Microsoft 365 MSO.Results and Discussion Five cockle capture tools were used in the traditional fishing of this bivalve in the Ria de Aveiro. The average minimum size of the cockle for capture was 23.4 mm, and the average capture per tide was 137.12 kg. The areas with the highest productivity and the most shellfish were RIAV1 and RIAV2. The habitat of the cockle is usually areas of sand and mud to an average depth of 2.71 cm. Feeds mainly small particles, plankton, mud, and algae. The main predators were crabs, European plaice, and bird species. Cockles spawn primarily in late spring and summer. As of 2010, there was a slight decrease in cockle stocks in the Ria de Aveiro due to overfishing, increased rainfall, and changes in the sediment. Shellfishers shared informal ecological and biological data often compared to previously published data for the species. Deeply considering and analyzing this knowledge is essential for a better understanding of the environmental context in the view of users of the natural resource in the Ria de Aveiro. ConclusionInformal data shared by shellfishers in the Ria de Aveiro were typical of filter-feeding bivalve mollusks. LEK may assist in planning future management plans for cockles, and unrefuted data may serve as untestable hypotheses. Understanding how fishers exploit the natural resource in the ecosystem can clarify and shape more adaptive socio-ecological actions. Ethnobiological studies in the Ria de Aveiro lagoon with other species may contribute to better management of this system since multiple fisheries are carried out in this coastal area.

What Is the Minimum Volume of Sample to Find Small Microplastics: Laboratory Experiments and Sampling of Aveiro Lagoon and Vouga River, Portugal

Small microplastics (<1 mm) comprise a great fraction of microplastics (<5 mm) found in the environment and are often overlooked due to the constrains of transporting and filtering large volumes of water in grab samplings. The objective of this work was to determine the minimum volume for reliable quantification of small microplastics in the environment. Different volumes (0.1, 0.25, 0.5, 1, 2.5 L) of laboratory spikes (fresh and saltwater) and environmental samples were filtered. Sampling volumes of 0.5 L or 1 L are a good compromise between drawbacks, such as effort, time, organic and mineral matter, potential contamination, and reliability of results, evaluated by interquartile range, accuracy, coefficient of variation, and recovery rates. Moreover, the observation of Nile Red-stained environmental samples under 470 nm produced six-times higher concentrations than samples under 254 nm, namely, 18 microplastics L−1 and 3 microplastics L−1 for the Aveiro Lagoon and 1 microplastics L−1 and 0 microplastics L−1 for the Vouga River, Portugal. This work also raises concerns about the underreporting of environmental concentrations of microplastics.

Climate Change Impact in the Ria de Aveiro Lagoon Ecosystem: A Case Study

Climate change and global sea-level rise are major issues of the 21st century. The main goal of this study is to assess the physical and biogeochemical status of the Ria de Aveiro lagoon (Portugal) under future climate scenarios, using a coupled physical/ eutrophication model. The impact on the lagoon ecosystem status of the mean sea level rise (MSLR), the amplitude rise of the M2 tidal constituent (M2R), the changes in the river discharge, and the rising of the air temperature was investigated. Under MSLR and M2R, the results point to an overall salinity increase and water temperature decrease, revealing ocean water dominance. The main lagoon areas presented salinity values close to those of the ocean waters (~34 PSU), while a high range of salinity was presented for the river and the far end areas (20–34 PSU). The water temperature showed a decrease of approximately 0.5–1.5 °C. The responses of the biogeochemical variables reflect the increase of the oceanic inflow (transparent and nutrient-poor water) or the reduction of the river flows (nutrient-rich waters). The results evidenced, under the scenarios, an overall decreasing of the inorganic nitrogen concentration and the carbon phytoplankton concentrations. A warm climate, although increasing the water temperature, does not seem to affect the lagoon’s main status, at least in the frame of the model used in the study.

FORAMINIFERA CHECK LIST AND THE MAIN SPECIES DISTRIBUTION IN THE AVEIRO LAGOON AND ADJACENT CONTINENTAL SHELF (PORTUGAL)

This work is based on a compilation of benthic foraminiferal data collected in the Aveiro Lagoon and in the adjacent continental shelf and upper slope (center of Portugal). It intends to provide an overall analysis from transitional to the outer continental shelf of the occurrence and distribution of species in living and to present updated taxonomic data and illustrations of most of the species found in the in the Aveiro Lagoon and in the adjacent continental shelf including in total assemblages. Cluster analysis (CA) and Principal Components Analysis (PCA) interpreted as depth functions allow us to identify the main species in different ecoenvironments and sectors of the study area. The most unusual living assemblage was documented in the lagoon inlet under very strong tidal currents activity, composed mostly by the following species (both in living and total assemblages): Rotaliammina concava, Lepidodeuterammina ochracea, Quinqueloculina seminula, Gavelinopsis praegeri, Paratrochammina haynesi, Remaneica helgolandica and Remaneicella gonzalezi. The distribution patterns of some Trochamminidae and Remaneicidae species whose ecology and distribution pattern are poorly known, have proved to be a marker of more or less hydrodynamic and stable/unstable environments in coastal and transitional marine environments. OCORRÊNCIA DE FORAMINÍFEROS E DISTRIBUIÇÃO DAS PRINCIPAIS ESPÉCIES NA LAGOA DE AVEIRO E NA PLATAFORMA CONTINENTAL ADJACENTE (PORTUGAL)ResumoEste trabalho baseia-se numa compilação de dados foraminíferos bentónicos recolhidos na Laguna de Aveiro e na plataforma continental adjacente (centro de Portugal). Pretende efetuar uma análise geral da distribuição de espécies nas associações vivas e totais (vivas e mortas) na área de estudo, em função da profundidade. Pretende ainda apresentar dados taxonómicos e ilustrações da maioria das espécies encontradas na Laguna de Aveiro e na plataforma continental adjacente. A análise de agrupamento (CA) e a análise de componentes principais (PCA), em função da profundidade, permitem identificar as principais espécies em diferentes ecossistemas e setores da área de estudo. A associação viva mais invulgar foi encontrada na embocadura da Laguna de Aveiro, um ambiente sujeito a forte corrente de maré. Essa associação era composta principalmente pelas seguintes espécies (na associação viva e total): Rotaliammina concava, Lepidodeuterammina ochracea, Quinqueloculina seminula, Gavelinopsis praegeri, Paratrochammina haynesi, Remaneica helgolandica and Remaneicella gonzalezi. Os padrões de distribuição de algumas espécies de Trochamminidae e Remaneicidae, cuja ecologia e padrão de distribuição são pouco conhecidos, mostraram ser um marcador de ambientes mais ou menos hidrodinâmicos e de estabilidade/instabilidade do substrato em ambientes marinhos costeiros e de transição. Palavras-chave: Ecologia. Taxonomia. Imagens digitais. Análise Estatística. Ambientes Transicionais e Costeiros Marinhos.