Identification of potential invasive alien species in Spain through horizon scanning.

Invasive alien species have widespread impacts on native biodiversity and ecosystem services. Since the number of introductions worldwide is continuously rising, it is essential to prevent the entry, establishment and spread of new alien species through a systematic examination of future potential threats. Applying a three-step horizon scanning consensus method, we evaluated non-established alien species that could potentially arrive, establish and cause major ecological impact in Spain within the next 10 years. Overall, we identified 47 species with a very high risk (e.g. Oreochromis niloticus, Popillia japonica, Hemidactylus frenatus, Crassula helmsii or Halophila stipulacea), 61 with high risk, 93 with moderate risk, and 732 species with low risk. Many of the species categorized as very high or high risk to Spanish biodiversity are either already present in Europe and neighbouring countries or have a long invasive history elsewhere. This study provides an updated list of potential invasive alien species useful for prioritizing efforts and resources against their introduction. Compared to previous horizon scanning exercises in Spain, the current study screens potential invaders from a wider range of terrestrial, freshwater, and marine organisms, and can serve as a basis for more comprehensive risk analyses to improve management and increase the efficiency of the early warning and rapid response framework for invasive alien species. We also stress the usefulness of measuring agreement and consistency as two different properties of the reliability of expert scores, in order to more easily elaborate consensus ranked lists of potential invasive alien species.

The journey of hull-fouling mobile invaders: basibionts and boldness mediate dislodgement risk during transit.

Vessel hull-fouling is responsible for most bioinvasion events in the marine environment, yet it lacks regulation in most countries. Although experts advocate a preventative approach, research efforts on pre-arrival processes are limited. The performance of mobile epifauna during vessel transport was evaluated via laboratory simulations, using the well-known invasive Japanese skeleton shrimp (Caprella mutica), and its native congener C. laeviuscula as case study. The invader did not possess any advantage in terms of inherent resistance to drag. Instead, its performance was conditioned by the complexity of secondary substrate. Dislodgement risk was significantly reduced when sessile fouling basibionts were added, which provided refugia and boosted the probability of C. mutica remaining attached from 7 to 65% in flow exposure trials. Interestingly, the invader exhibited significantly higher exploratory tendency and motility than its native congener at zero-flow conditions. Implications in terms of en-route survivorship, invasion success and macrofouling management are discussed.

Ecological quality assessement of marinas: An integrative approach combining biological and environmental data.

The importance of marinas as infrastructures for recreational boating is increasing substantially. However, information on their soft-bottom benthic communities, a key tool for managing programmes, is still scarce. We combined environment features with macro- and meiofaunal soft-bottom community information for assessing the ecological status of marinas with an integrative approach. To address this issue, we focused on eight marinas of the Southern Iberian Peninsula. Macro- and meiofauna data revealed high benthic heterogeneity at a spatial scale. The environmental variables which correlated best with macrofauna were mainly phosphorus, granulometry, and total organic carbon, and secondarily important variables were faecal coliforms, the biocide Irgarol, and heavy metals; total hydrocarbon concentration was also significant for meiofauna. Annelida was the dominant phylum in terms of number of species (37%) and abundance (66%) and were better descriptors of the environmental conditions than Arthropoda and Mollusca. Although identification to the species level is desirable and mandatory for assessing biological pollution, significant differences among marinas and correlations between fauna and abiotic variables were already detected at the level of family and order. This implies that biota assessment at higher levels may still be useful in monitoring programmes limited by time and budget constraints. The major novelty of this study lies in the development of an integrative assessment method based on the following selected ecological indicators: Marinas Environmental Pollution Index (MEPI), Biocontamination Index (BCI), macrofaunal biotic indices (AMBI, M-AMBI, BENTIX, MEDOCC and BENFES), macrofaunal taxa richness and Shannon-Wiener's diversity, and nematode:copepod index. This approach was able to discriminate marinas of the Southern Iberian Peninsula based on their ecological status, which ranged from poor to good. The method can be useful to design standards for assigning "sustainable quality seals" to those marinas with better values of ecological indicators.

Is the invasive Caprella scaura Templeton, 1836 displacing its resident congener Caprella equilibra Say, 1818 in marinas of the South Iberian Peninsula? A long-term spatio-temporal approach.

Although marine invasions are increasingly a matter of concern, the impact of invasive species in the ecosystem and their ability to replace native taxa is still little understood. Data from 2011 to 2021 in marinas of the Southern Iberian Peninsula supported that the invasive amphipod Caprella scaura is replacing the resident Caprella equilibra over time. Six marinas where C. equilibra was abundant in 2011 and C. scaura was absent, are now dominated by C. scaura. Although this displacement is more evident in Mediterranean shores than in Atlantic coasts, it is very variable between marinas. The spreading of the invasive species in marinas of the Alboran Sea mainly occurred from 2011 to 2017, preventing C. equilibra from regaining its former distribution. The ultimate factors responsible for the displacement, such as the aggressive behaviour of C. scaura, environmental influences or physiological performance in a global warming context, should be further investigated experimentally.

Leakage of plastics and other debris from landfills to a highly protected lake by wintering gulls.

GENERAL CONTEXT: Gulls ingest plastic and other litter while foraging in open landfills, because organic matter is mixed with other debris. Therefore, gulls are potential biovectors of plastic pollution into natural habitats, especially when they concentrate in wetlands for roosting. NOVELTY: We quantified, for the first time, the flow of plastic and other anthropogenic debris from open landfills to a natural lake via the movement of gulls. We focused on Fuente de Piedra, an inland closed-basin lake in Spain that is internationally important for biodiversity. METHODOLOGY: In 2022, we sampled gull pellets regurgitated in the lake by lesser black-backed gulls Larus fuscus that feed on landfills, as well as their faeces, then characterized and quantified debris particles of ≥0.5 mm. By combining GPS and census data from 2010 to 2022, together with plastic quantification based on FTIR-ATR analysis, we estimated the average annual deposition of plastic and other debris by the wintering gull population into the lake. MAIN RESULTS: 86 % of pellets contained plastics, and 94 % contained other debris such as glass and textiles. Polyethylene (54 %), polypropylene (11.5 %) and polystyrene (11.5 %) were the main plastic polymers. An estimated annual mean of 400 kg of plastics were moved by gulls into the lake. Only 1 % of plastic mass was imported in faeces. DISCUSSION: Incorporating the biovectoring role of birds can provide a more holistic view of the plastic cycle and waste management. Biovectoring is predictable in sites worldwide where gulls and other waterbirds feed in landfills and roost in wetlands. We discuss bird deterrence and other ways of mitigating debris leakage into aquatic ecosystems.

Estuarine versus coastal marinas: Influence of the habitat on the settlement of non-indigenous peracarids on the polychaete Sabella spallanzanii (Gmelin, 1791).

Recreational marinas are key points for the introduction and secondary spread of non-indigenous species (NIS). However, little is known about the influence of the habitat surrounding the marina on NIS communities. To explore this issue, we compared peracarid assemblages associated to the widespread ecosystem engineer Sabella spallanzanii in lower estuarine marinas (with oceanic salinity) and coastal marinas of the south of the Iberian Peninsula. Sabella spallanzanii hosted a total of 23 species, 7 of them NIS. While NIS richness was similar between marinas located in estuaries and coastal habitats, NIS abundance was significantly higher in estuarine marinas. The NIS community structure was influenced by both the marina itself and the surrounding habitat. These results suggest that lower estuarine conditions promote NIS abundance in marinas, increasing potential invasion risks. This supports prioritization of estuarine marinas in NIS monitoring programs and the suitability of S. spallanzanii as a bioinvasion monitoring tool.

Biovectoring of plastic by white storks from a landfill to a complex of salt ponds and marshes.

Research into plastic pollution has extensively focused on abiotic vectors, overlooking transport by animals. Opportunistic birds, such as white storks (Ciconia ciconia) often forage on landfills, where plastic abounds. We assess plastic loading by ingestion and regurgitation of landfill plastic in Cadiz Bay, a major stopover area for migratory white storks in south-west Spain. On average, we counted 599 storks per day moving between a landfill and a complex of salt ponds and marshes, where they regurgitated pellets that each contained a mean of 0.47 g of plastic debris, dominated by polyethylene. Modelling reliant on GPS tracking estimated that 99 kg and >2 million particles of plastic were biovectored into the wetland during 2022, with seasonal peaks that followed migration patterns. GPS data enabled the correction of field censuses and the identification of plastic deposition hotspots. This study highlights the important role that biovectoring plays in plastic transport into coastal wetlands.

A horizon scan exercise for aquatic invasive alien species in Iberian inland waters.

As the number of introduced species keeps increasing unabatedly, identifying and prioritising current and potential Invasive Alien Species (IAS) has become essential to manage them. Horizon Scanning (HS), defined as an exploration of potential threats, is considered a fundamental component of IAS management. By combining scientific knowledge on taxa with expert opinion, we identified the most relevant aquatic IAS in the Iberian Peninsula, i.e., those with the greatest geographic extent (or probability of introduction), severe ecological, economic and human health impacts, greatest difficulty and acceptability of management. We highlighted the 126 most relevant IAS already present in Iberian inland waters (i.e., Concern list) and 89 with a high probability of being introduced in the near future (i.e., Alert list), of which 24 and 10 IAS, respectively, were considered as a management priority after receiving the highest scores in the expert assessment (i.e., top-ranked IAS). In both lists, aquatic IAS belonging to the four thematic groups (plants, freshwater invertebrates, estuarine invertebrates, and vertebrates) were identified as having been introduced through various pathways from different regions of the world and classified according to their main functional feeding groups. Also, the latest update of the list of IAS of Union concern pursuant to Regulation (EU) No 1143/2014 includes only 12 top-ranked IAS identified for the Iberian Peninsula, while the national lists incorporate the vast majority of them. This fact underlines the great importance of taxa prioritisation exercises at biogeographical scales as a step prior to risk analyses and their inclusion in national lists. This HS provides a robust assessment and a cost-effective strategy for decision-makers and stakeholders to prioritise the use of limited resources for IAS prevention and management. Although applied at a transnational level in a European biodiversity hotspot, this approach is designed for potential application at any geographical or administrative scale, including the continental one.

Exploring biocontamination in associated macrofaunal assemblages in marinas: Soft bottoms vs artificial hard substrate. Where and what to look for?

Marinas are hot spots of non-indigenous marine species (NIS). Introductions of NIS, regardless of their actual or potential impacts, can be considered as a biocontamination of the ecosystem. To characterize the biocontamination status of a marina it is important to know which habitats and major taxa can provide the most useful information. To address this issue, we analyze the associated macrofaunal community associated to soft substrate (sediment; SS) and artificial hard substrate (lateral surface of pontoons; AHS) of six marinas from Southern Spain. 9 NIS were found, including 8 crustaceans (7 peracarids) and 1 polychaete; 8 NIS were found on AHS and 4 in sediments. Indeed, site-specific BioContamination Index (SBCI) showed higher values in AHS than SS. Our results indicate peracarids in AHS should be the primary target for assessing the level of biocontamination in marinas. This may help scientists and environmental managers to stablish strategies for monitoring marine bioinvasions.

Environmental stress responses in sympatric congeneric crustaceans: Explaining and predicting the context-dependencies of invader impacts.

The role of ecophysiology in mediating marine biological pollution is poorly known. Here we explore how physiological plasticity to environmental stress can explain and predict the context-dependencies of invasive species impacts. We use the case of two sympatric skeleton shrimps, the invader Caprella scaura and its congener C. equilibra, which is currently replaced by the former on the South European coast. We compare their physiological responses to hyposalinity stress under suboptimal low and high temperature, while inferring on hypoxia tolerance. We use an energy-redox approach, analyzing mortality rate, the energetic balance and the consequent effects on the oxidative homeostasis. We found that decreased seawater salinity and/or oxygen levels can weaken biotic resistance, especially in females of C. equilibra, leading to periods of heightened vulnerability to invasion. Our approach provides mechanistic insights towards understanding the factors promoting invader impacts, highlighting the potential of ecophysiology for improving invasive species management.

Assessing environmental pollution levels in marinas.

Despite the growing interest in recreational boating and the increasing number of marinas along the world's coastlines, environmental knowledge of these ecosystems is still very scarce. Detailed data of pollutants in marinas are necessary to provide a global approach of environmental risks in the context of international management strategies. In the present study, a set of 64 variables (30 in seawater and 34 in sediments) were measured to compare marinas from the Southern Iberian Peninsula (SIP). Uni and multivariate analyses showed significant differences among marinas, evidencing the importance of management on a local scale. The most relevant variables determining these differences were turbidity and the biocide Irgarol 1051 in seawater, and granulometry, hydrocarbons and faecal coliforms in sediment. The use of normalization techniques with Al or Fe, and the suitability of different methodologies to measure Total Organic Matter in marinas were also discussed. Additionally, we perform a comprehensive literature review of worldwide marina stressors and develop a simple and straightforward method for assessing environmental quality. The method was tested using SIP marinas and was based on the comparison of 15 selected sediment stressors with background values, concentrations of worldwide sediment quality guidelines (SQGs), and reference conditions/security thresholds established by the programme of coastal waters in port areas (ROM 5.1). A global score was assigned using a new proposed index, Marinas Environmental Pollution Index (MEPI), ranging from 0 to 150 points according to the environmental quality (<90: bad, 90-120: moderate, >120: good). MEPI of marinas from SIP ranged from 60 to 110 points indicating bad or moderate levels of pollution. Environmental quality is one of the decisive factors for awarding eco-labels or eco-certifications, such as Blue Flags in marinas. Therefore, pollution baseline information and environmental tools are mandatory for correct assignation of these awards and necessary for assessing the efficiency of management actions.

Pore-size and polymer affect the ability of filters for washing-machines to reduce domestic emissions of fibres to sewage.

When clothes are worn and washed, they emit fibres into the ecosystem via discharges of sewage that have been linked to the global dispersion of clothing fibres. Facilities that treat sewage divert some fibres from sewage effluent to sludge, but no current methods of filtration eliminate their environmental release. While filters for washing-machines are sold to consumers with the argument they will reduce the emissions of fibres from clothes to the environment, there is insufficient scientific peer-reviewed evidence assessing their ability to retain fibres from washed clothes and reduce environmental contamination. To improve our understanding and develop more realistic methods to assess the efficiency of filters, we washed replicate cotton and polyester garments in replicate domestic front-loaded washing-machines with and without replicate filters (micro- and milli-meter-sized pores), and then quantified the masses of the fibres retained by the filters and those released in the effluent. Here we show micrometer-sized filters significantly reduced the mass of cotton by 67% (F2,6 = 11.69, P<0.01) compared to effluent from appliances with no filters, whilst filters in general reduced polyester fibres in their effluent by more than 65% (micrometer-sized pores) and 74% (millimeter-sized pores) compared to effluent from appliances with no filters (F2,12 = 5.20, P<0.05). While filters with micrometer-sized pores caught larger masses and total proportions of fibres than filters with millimeter-sized pores, the differences were only significant for the total proportions of cotton (t = 4.799 df = 4, P<0.01). For tests with garments of either types of polymer, the filtered effluent still contained up to a third of the original masses of fibres released from the garments. Given the diversity of clothes, polymers, appliances and filters currently sold to consumers, our work shows the value of increasing the rigour (e.g. more levels of replication) when testing filters and the need for further studies that test an even greater diversity of materials and methods in order to meet the growing demand for knowledge from governments, industry and the public.

Marine exotic isopods from the Iberian Peninsula and nearby waters.

Effective management of marine bioinvasions starts with prevention, communication among the scientific community and comprehensive updated data on the distribution ranges of exotic species. Despite being a hotspot for introduction due to numerous shipping routes converging at the Strait of Gibraltar, knowledge of marine exotics in the Iberian Peninsula is scarce, especially of abundant but small-sized and taxonomically challenging taxa such as the Order Isopoda. To fill this gap, we conducted several sampling surveys in 44 marinas and provide the first comprehensive study of marine exotic isopods from the Iberian Peninsula, the southern side of the Strait of Gibraltar (northern Africa) and the Balearic Islands. Exotic species included Ianiropsis serricaudis (first record for the Iberian Peninsula and Lusitanian marine province), Paracerceis sculpta (first record for the Alboran Sea ecoregion), Paradella dianae, Paranthura japonica (earliest record for the Iberian Peninsula) and Sphaeroma walkeri. Photographs with morphological details for identification for non-taxonomic experts are provided, their worldwide distribution is updated and patterns of invasion are discussed. We report an expansion in the distribution range of all species, especially at the Strait of Gibraltar and nearby areas. Ianiropsis serricaudis and Paranthura japonica are polyvectic, with shellfish trade and recreational boating being most probable vectors for their introduction and secondary spread. The subsequent finding of the studied species in additional marinas over the years points at recreational boating as a vector and indicates a future spread. We call for attention to reduce lags in the detection and reporting of small-size exotics, which usually remain overlooked or underestimated until the invasion process is at an advanced stage.

Impoverished mobile epifaunal assemblages associated with the invasive macroalga Asparagopsis taxiformis in the Mediterranean Sea.

There is an increasing concern about the ecosystem consequences of altering macroalgal assemblages. Many macrophytes are foundation species in coastal habitats, supporting much of the biodiversity of these ecosystems by providing essential resources such as food and habitat. The addition of invasive species strongly contributes to habitat modification, but the bottom-up impacts of non-native macroalgae on higher trophic levels remains difficult to predict. The main aim of this study was to evaluate the effects of the invasive macroalga Asparagopsis taxiformis on biodiversity by comparing the mobile macrofauna inhabiting this species to the dominant native species Halopteris scoparia. This is the first comprehensive study of the possible effects of this widespread invasive species on higher trophic levels. A hierarchical sampling design with two different spatial scales was conducted to explore the consistency of the patterns observed. Fifty-nine species belonging to superorder Peracarida were found, accounting 90% of all organisms. A. taxiformis hosted an impoverished epifaunal assemblage in comparison to that associated with the native seaweed, showing significantly lower values of diversity, abundance and number of epifaunal species across study locations. The structure of the associated macrofauna (both in terms of species composition, variability among samples and relative abundance of the species) was also different. Our results highlighted the strong influence of A. taxiformis in the resident community, with differences among the two macroalgae in all the parameters considered. Finally, our results also reflect a biotic homogenization of the epifaunal assemblages associated to A. taxiformis, a scarcely explored consequence of invasive processes in marine environments. Future studies exploring the cascading effects of the observed changes in the epifaunal assemblages would be necessary in order to estimate system responses to macroalgal invasions.

A new caprellid species (Crustacea: Amphipoda: Senticaudata) from Brazil.

A new species of caprellid, Pseudaeginella arraialensis, is described from Arraial do Cabo, Rio de Janeiro, Brazil. Abundant material was collected in Praia do Forno, associated to hydroids and algae of natural rocky substrata and fouling communities of artificial floating structures. The new species can be distinguished easily from the remaining species in the genus mainly by the pattern of dorsal projections, and by the setose antennae and gnathopod 2 in males. The dietary analysis revealed that the species is omnivorous, with a high contribution of small crustaceans in its diet. Detailed figures showing ontogenetic development and intraspecific variation of P. arraialensis are also included.

Towards Integrated Multi-Trophic Aquaculture: Lessons from Caprellids (Crustacea: Amphipoda).

The search for alternative live feed organisms and the progression of Integrative Multi-Trophic Aquaculture (IMTA) are currently being highly prioritised in EU strategies. Caprellids could potentially be an important exploitable resource in aquaculture due to their high levels of beneficial polyunsaturated fatty acids, fast growing nature and widespread distribution. Furthermore, since they are mainly detritivorous, they could be excellent candidates for integration into IMTA systems, potentially benefitting from uneaten feed pellets and faeces released by cultured fish in fish farms and sea-cage structures. Despite this, there is a lack of experimental studies to: (i) test inexpensive diets for caprellids, such as detritus, (ii) develop sustainable caprellid culture techniques and (iii) include caprellids in IMTA systems. The main aim of this study was to determine whether detritus (D) in the form of fish faeces provided an adequate diet for caprellids in comparison to other traditional diets, such as Artemia nauplii (A) or phytoplankton (P). Adult survival rate was shown to be significantly higher for caprellids fed with D. Conversely, hatchlings had the highest survival rate with A, although the juvenile growth rate and number of moults was similar in the three diets. With regard to lipid composition, caprellids fed with A had higher concentrations of Triacylglycerols (TAG) and Phosphatidylcholine (PC) while those fed with P or D were richer in polyunsaturated fatty acids, especially 22:6(n-3) (DHA). Interestingly, caprellids fed with D were also a rich source of 18:2(n-6) (LA), considered to be an essential fatty acid in vertebrates. It was found that detritus based mainly on fish faeces and uneaten feed pellets can be considered an adequate feed for adult caprellids, providing a source of both omega-3 (DHA) and omega-6 (LA) fatty acids. Hatchlings however seem to require an additional input of TAG and PC during juvenile stages to properly grow.

Environmental factors modulating the extent of impact in coastal invasions: The case of a widespread invasive caprellid (Crustacea: Amphipoda) in the Iberian Peninsula.

Understanding the respective roles of environment and interspecific interactions in shaping species' distributions is a critical aspect in determining the potential impacts of newcomer species on occupied habitats. The invasive caprellid amphipod Caprella scaura has successfully spread along southern Europe in a short time period, coinciding with a decline in the population of an ecologically similar congener, Caprella equilibra. To understand the mechanisms underlying the establishment success of this aggressive species and its potential role in shaping C. equilibra's distribution, we analyze the biotic and abiotic factors involved in the patterns of distribution and co-occurrence of both species along the Iberian Peninsula and northern Africa. Our analyses support that C. scaura is competitively displacing C. equilibra from the study area, but also point out the critical role of salinity and temperature in modulating this interaction and limiting the invasive success of C. scaura on the Iberian North-Atlantic coast.

The Panama Canal and the transoceanic dispersal of marine invertebrates: evaluation of the introduced amphipod Paracaprella pusilla Mayer, 1890 in the Pacific Ocean.

Although the Panama Canal is one of the major corridors for shipping and potential dispersal of marine invaders in the tropics, little is known about the effect that the Canal has had on the distribution of marine biota. In this study, we (a) document the existence of established populations of the Western Atlantic caprellid amphipod Paracaprella pusilla, Mayer, 1890 for the first time at the Pacific entrance to the Canal, (b) review its distribution in the Pacific Ocean, and (c) evaluate possible mechanisms of introduction. The confirmed distribution of P. pusilla in the Pacific Ocean is limited to Australia, Hawaii, and Panama, despite earlier published reports from Chile and China. Laboratory experiments demonstrated intolerance of P. pusilla to freshwater, causing 100% mortality, and suggest invasion of the Pacific coast of Panama occurred through the Canal via ships' ballast water or by secondary spread via ships (ballast water or hull fouling) from another Pacific region.