Patterns of Distribution of Bivalve Populations in a Mediterranean Temporary River

In the south of the Iberian Peninsula, many rivers are intermittent, a state most likely to be exacerbated by climate change, strongly affecting river biota. An additional challenge for native biota in this area is the arrival of new species, frequently aided by humans, and bivalves are particularly at risk. Here we assessed whether the native (Unio delphinus) and invasive (Corbicula fluminea) bivalves differed in habitat use. To address this question, we sampled populations of both species in six isolated permanent pools in the same river during summer in three consecutive years. U. delphinus occurred in all pools, while C. fluminea occurred only in the two most downstream pools. U. delphinus, but not C. fluminea, was found preferentially in patches under riparian vegetation cover. Both species were found in similar sediment types (coarse and fine gravel respectively). Although U. delphinus was present in all pools, recruitment was detected only in 2016, in one pool. We concluded that both species have the potential to compete for space, but a well-developed riparian vegetation cover may provide U. delphinus some advantage against C. fluminea

Angler’s preferences, perceptions and practices regarding non-native freshwater fish

It is globally recognized that freshwater anglers can have a decisive role in promoting fish introductions. The aim of this study was to analyze fresh water anglers’ actions and perceptions regarding fish introductions, comparing two distinct situations, one with recently arrived non-natives fishes and another with older fish introductions, using the Iberian Peninsula as a case study. To achieve this goal, a bilingual survey was implemented on-line in Portugal and Spain and in person (direct inquiries) in two Iberian regions: Lower Ebro (older fsh introductions) in Spain; and Lower Tagus (recent fish introductions) in Portugal. Results showed spatial diferences in perceptions and actions, namely about the target species, awareness of the impact of non-native fishes, fish introductions reported and proportion of anglers that wanted new fish species. In the Ebro river there is a high percentage of foreign anglers, higher awareness of fish introduction impact and lower introduction rates reported than in the Tagus river. However, popularity of non-native species like European catfish, was higher in the Ebro. In general, although risk behaviors such as use of fish as life bait was of low prevalence for both countries (approx. 5%), it corresponds to large numbers of fish being introduced. Our conservative estimates revealed 273,600 events of bait discharge per year. Regarding the intentional introductions, we estimated a total of 140,000 intentional introduction (illegal) events per year. These findings may help to improve monitoring, awareness and fisheries management programs led by governmental agencies.Fundação para a Ciência e a Tecnologia; Comissão Europeia; Governo da Catalunhainfo:eu-repo/semantics/publishedVersio

O peixe-gato-europeu (Silurus glanis) - um gigante no rio tejo: dispersão, distribuição e ecologia

O peixe gato europeu (Silurus glanis) é mais uma espécie não nativa que foi introduzida nos rios da Península Ibérica. Neste trabalho é apresentado o padrão de dispersão desta espécie no rio Tejo desde o primeiro registo em Espanha em 1998 até à atualidade. Mais de 80 registos foram obtidos principalmente através de fóruns e blogs de pesca desportiva. Atualmente estima-se que esta espécie esteja distribuída por mais de 700 km de linhas de água do rio Tejo e que ocupe preferencialmente zonas de albufeiras em cursos de água de ordem elevadas. Adicionalmente foi analisada a dieta de peixes capturados no rio Tejo por pescadores profissionais ao longo de 2016 e 2017 e os resultados preliminares são apresentados. Foram encontradas diferenças na composição da dieta entre os indivíduos de habitats lóticos e lênticos sendo que o grupo dos Crustáceos seguido dos Teleósteos foram as presas mais representativas. Também são discutidos os impactos desta espécie não nativa na composição, estrutura e funcionamento do ecossistema fluvial do rio Tejo

Comercio Electrónico de flora y fauna exótica invasora (código de conducta)

Este código de conducta pretende alertar de la venta y adquisición on-line de especies invasoras y fomentar una serie de recomendaciones que ayuden a reducir el riesgo que conlleva el comercio electrónico como vía de introducción de fauna y flora invasora. Los principales destinatarios de este código de conducta son: Profesionales dedicados al comercio de plantas y animales de compañía y a la acuariofilia: importadores (mayoristas), intermediarios (comercializadores y distribuidores) y tiendas (minoristas).Consumidores: aficionados y usuarios de jardinería, mascotismo o acuariofilia. Este código de conducta ha sido redactado en el marco del proyecto LIFE INVASAQUA (LIFE17 GIE/ES/000515) con la contribución de la Comisión Europea a través del programa LIFE. El proyecto LIFE INVASAQUA tiene entre sus objetivos facilitar y apoyar las políticas europeas sobre gestión de especies exóticas invasoras generando información útil para su implementación. Los códigos de conducta son documentos que pretenden fomentar una serie de recomendaciones y buenas prácticas para reducir la problemática asociada a la introducción de fauna y flora invasora. Esta versión 1.0 del documento tiene por objeto difundir la información entre organismos, asociaciones y entidades relacionadas para fomentar la adopción de sus recomendaciones y recoger nuevas aportaciones.El proyecto LIFE INVASAQUA (LIFE17 GIE/ES/000515) está financiado por el Programa LIFE de la Unión Europe

Black list and Alert list of the Aquatic Invasive Alien Species in the Iberian Peninsula: an action of the LIFE INVASAQUA

Resumen del trabajo presentado en VI Congreso Nacional sobre Especies Exóticas Invasoras y I Congreso Ibérico sobre EEI (EEI 2022) celebrado en Navarra del 20 al 23 de abril de 2022.One of the objectives of LIFE INVASQUA project is to develop tools that will be more efficient the Early Warning and Rapid Response (EWRR) framework for Invasive Alien Species in the Iberian Peninsula. Horizon scanning for high-risk IAS is basic in implementing measures to reduce new invasions, developing Alert lists, and to focus effort in the species already established, for instance making a Black list. We developed a trans national horizon scanning exercise focused on inland waters of Spain and Portugal in order to provide a prioritized lists (Black list and Alert list) of aquatic IAS that may pose a threat to aquatic ecosystems and socio economic sectors in the future. We followed a step approach of existing information about IAS (Plants, Freshwater Invertebrates, Estuarine Invertebrates and Vertebrates; 127 established taxa in Black list; 90 non established taxa in Alert list) combining with an expert scoring of prioritized taxa. IAS established in the Iberian aquatic system consistently highlighted as the worst included vertebrates (e.g. Cyprinus carpio, Gambusia holbrooki, Silurus glanis), freshwater and estuarine invertebrates (e.g. Procambarus clarkii, Dreissena polymorpha, Pacifastacus leniusculus, Ficopomatus enigmaticus, Callinectes sapidus, Corbicula fluminea) and plants (e.g. Eichhornia crassipes, Azolla filiculoides, Ludwigia grandiflora). Amongst taxa not yet established (Alert list), expert pointed to Perna viridis, Hydroides dirampha, Dreissena bugensis, Procambarus fallax f. virginallis, Perccottus glenii with higher risk of invasion, ecological and socioeconomic impacts. Over 20.6% of the taxa in the preliminary black list received no votes (no prioritization) by experts, 17.8% in the innitial alert list. Our horizon scanning approach is inclusive of all-taxa, prioritizes both established and emerging biological threats across trans-national scales, and considers not only the ecological impact, but also potential direct economic consequences as well as the manageability of invasive species.This work received funds from the LIFE Programme (LIFE17 GIE/ES/000515)

Código de conduta. Prevenção da introdução e dispersão de flora e fauna exótica invasora: agentes ambientais

De forma intencional ou involuntária, o ser humano transporta espécies entre locais desde tempos imemoriais. No entanto, nos últimos 50 anos, o ritmo de introdução de espécies exóticas no meio natural acelerou de forma alarmante, tornando-se numa das principais causas de perda de biodiversidade. A globalização, juntamente com as alterações climáticas, a destruição de habitats, o aumento do trânsito de pessoas e o comércio, são hoje os principais responsáveis pela perda de biodiversidade a nível global, acarretando também graves prejuízos para a economia e a saúde humana

Interactions between invasive crayfish and native river shrimp

In the south of Portugal there are only two species of strictly freshwater decapods: the native freshwater shrimp Atyaephyra desmarestii and the exotic crayfish Procambarus clarkii. The aim of this study is to understand if the exotic crayfish acts as river shrimp predator and if both species share the same type of microhabitat. We performed laboratory experiments to study predation and conducted field work in the river Sorraia to verify the microhabitat distribution of both species. Laboratory experiments demonstrated significant predation on river shrimp for crayfish with a cephalothorax length (CT) over 24 mm. The average daily consumption increases with crayfish CT to a maximum of 0.8 shrimps at 44 mm. Field work confirmed that both species share the same microhabitats although with small differences e.g. on the water quality variables such as conductivity and the percentage of oxygen saturation. These microhabitats are shallow pools with abundant aquatic vegetation with no preference for the type of substrate. In the field, both crayfish density and its cephalothorax length are negatively correlated with shrimp densities. In conclusion, P. clarkii can predate A. desmarestii and the major impacts are expected at high densities of large sized crayfish

Interactions between invasive crayfish and native river shrimp

In the south of Portugal there are only two species of strictly freshwater decapods: the native freshwater shrimp Atyaephyra desmarestii and the exotic crayfish Procambarus clarkii. The aim of this study is to understand if the exotic crayfish acts as river shrimp predator and if both species share the same type of microhabitat. We performed laboratory experiments to study predation and conducted field work in the river Sorraia to verify the microhabitat distribution of both species. Laboratory experiments demonstrated significant predation on river shrimp for crayfish with a cephalothorax length (CT) over 24 mm. The average daily consumption increases with crayfish CT to a maximum of 0.8 shrimps at 44 mm. Field work confirmed that both species share the same microhabitats although with small differences e.g. on the water quality variables such as conductivity and the percentage of oxygen saturation. These microhabitats are shallow pools with abundant aquatic vegetation with no preference for the type of substrate. In the field, both crayfish density and its cephalothorax length are negatively correlated with shrimp densities. In conclusion, P. clarkii can predate A. desmarestii and the major impacts are expected at high densities of large sized crayfish

The effect of reproductive occurrences and human descriptors on invasive pet distribution modelling: Trachemys scripta elegans in the Iberian Peninsula

Pet release is important for the introduction of invasive species but propagule pressure from this pathway is higher in areas with intense human presence. In fact, potential invaders are frequently released into areas with sub-optimal environmental conditions, and are not able to reproduce or establish viable populations. SDMs are mainly focused on determining species environmental suitability and in the case of invasive species modelling these do not integrate the invasion as a process, missing the crucial human contribution. Our model aims to introduce novelty by incorporating variables representing human activities such as pet shop densities or human areas. These are directly related with the studied species invasion pathway. Here we investigate the binomial influence of reproductive occurrences and human-related variables on invasive pet distribution modelling. As our model species, we used the red-eared slider turtle, Trachemys scripta elegans (T.s.e.), an iconic invasive species with worldwide dissemination. Ten variables (predictors) were selected for T.s.e. modelling. These were four bioclimatic (BIO1 = Annual Mean Temperature, BIO10 = Mean Temperature of Warmest Quarter, BIO11 = Mean Temperature of Coldest Quarter and BIO12 = Annual Precipitation), three topographic (altitude, slope and the compound topographical index (CTI)), and three human variables (pet shop density, distance to urban areas and human density). To model suitability for T.s.e. establishment we tested four combinations of three sets of descriptor variables (human, environmental and both), with two types of occurrence records (reproductive or all records), at a global (worldwide) or regional scale (Iberian Peninsula (IP)). For each combination, an ensemble of niche-based models (NBMs) was built using nine different types of models implemented in BIOMOD2. In worldwide modelling, the use of reproductive occurrence records enables the most accurate predictions. At a regional scale, the combination of environmental and human variables promotes higher accuracy than using human variables alone. For worldwide and regional modelling, the most important variables are associated with temperature (Mean Temperature of Coldest Quarter; Annual Mean Temperature; Mean Temperature of Warmest Quarter). For regional modelling the human variable with highest importance was human density. Our approach may be useful for the management of released pet invaders, namely identifying high invasion risk areas where management efforts should be prioritized. From our models we recommend that T.s.e. management efforts should be prioritized to coastal and lowland areas. This study highlights that when modelling invasive species distributions, it is very important to use records that accurately represent species establishment (e.g. species breeding). Moreover, it clarified that variables associated to propagule pressure can improve model performance, even though these are much less used than bioclimatic variables. This modelling framework may be applied to other invasive species with different invasion pathways, by using different variables, directly linked with the respective invasion vectors and taking into account anthropogenic pressure. These modelling procedures should provide a better view of areas at risk of invasion, should improve management efforts and should also provide important insights on the role of human vectors on the shaping of invasive species distribution