Non-indigenous macrozoobenthic species on hard substrata of selected harbours in the Adriatic Sea

Cut the rope: Short-term colonization of mooring lines by fouling community within the port of Livorno (Northern Tyrrhenian Sea, Western Mediterranean), focusing on alien species recruitment

The early stages of fouling development on artificial substrates were examined for spatial-temporal variation in the commercial and touristic harbours (use destinations) of the port of Livorno (Tuscany, Italy). The experiment was carried out by submerging two types of experimental ropes with different surface textures, considering three times of submersion. Particular attention was paid to the colonization dynamics of non-indigenous species (NIS). The type of rope did not significantly affect fouling development. However, when the NIS assemblage and the whole community were taken into account, the colonization of ropes varied depending on the use destination. The touristic harbour exhibited a degree of fouling colonization higher than the commercial one. NIS were observed in both harbours since the beginning of colonization, eventually achieving higher population densities in the touristic harbour. The use of experimental ropes represents a promising quick cost-effective tool for monitoring of NIS presence in port environments.

Fish eDNA detections in ports mirror fishing fleet activities and highlight the spread of non-indigenous species in the Mediterranean Sea

Gathering comprehensive marine biodiversity data can be difficult, costly and time consuming, preventing adequate knowledge of diversity patterns in many areas worldwide. We propose fishing ports as "natural" sinks of biodiversity information collected by fishing vessels probing disparate habitats, depths, and environments. By combining rapid environmental DNA metabarcoding (eDNA) surveys and data from public registers and Automatic Identification Systems, we show significant positive relationships between fishing fleet activities (i.e. fishing effort and characteristics of the fishing grounds) and the taxonomic fish assemblage composition in eleven Mediterranean fishing ports. Overall, we identified 160 fish and 123 invertebrate OTUs, including at least seven non-indigenous species, in some instances well beyond their known distribution areas. Our findings suggest that eDNA assessments of fishing harbours' waters might offer a rapid way to monitor marine biodiversity in unknown or under-sampled areas, as well as to reconstruct fishing catches, often underreported in several regions.

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.

Short-term colonization of fouling communities within the port of Livorno (Northern Tyrrhenian Sea, Western Mediterranean): Influence of substrate three-dimensional complexity on non-indigenous species establishment

The influence of substrate morphology on early stages of fouling development was assessed through submerged experimental substrates with different morphological complexity. The experiment was carried out within commercial and touristic harbours of the port of Livorno (Italy), analysing the communities at three steps of colonization (14, 28, 42 days). We assessed the effect of substrate complexity on recruitment of non-indigenous species (NIS), combined with the influence of port use destinations. NIS were recorded in both use destination areas since the first step of colonization. Substrate morphological complexity significantly affected fouling colonization and particularly NIS assemblages. We found that high-complexity substrates are particularly suitable for NIS establishment in comparison with less complex ones. The touristic harbour exhibited a potential for fouling colonization higher than the commercial harbour. These results contributed to the understanding of factors involved in NIS establishment and spread, as well as in their spatial-temporal dynamics within port environments.

Biotic resistance of native fouling communities to bioinvasions could not be demonstrated by transplant experiments in Northern Italy

Biotic resistance is considered an important driver in the establishment of non-indigenous species (NIS), but experiments in the marine environment have led to contradictory results. In this context, a transplant experiment of fouling communities was carried out over five months. Settlement panels were moved from low impact (species-rich native communities) to high impact sites by NIS in two Italian areas to test the biotic resistance hypothesis. Fouling communities displayed significant differences among treatments before and after the transplant, thus indicating the maintenance of a peculiar fouling community in transplanted panels. On the other hand, newly recruited species were similar between treatments and neither a facilitation nor a mitigation role from native fouling communities on NIS was observed. Our results highlight the importance to better investigate the factors affecting the high variability obtained in experiments testing this hypothesis, with the aim to identify potential solutions for NIS management in ports.

Settlement of Bivalve Spat on Artificial Collectors (Net Bags) in Two Commercial Mussel Parks in the North-Western Adriatic Sea

Among aquaculture activities, shellfish culture is considered more sustainable and beneficial in terms of food security. Currently, only a few bivalve species are reared and there is a need to explore the possibility to introduce new candidates for shellfish farming. Due to the lack of information on bivalve recruitment in the North-Western Adriatic Sea, in this study, the possibility to collect natural spat of commercial species was investigated. Artificial collectors (net bags) were deployed in two sites, Pellestrina and Caleri (North-Western Adriatic Sea), within two commercial mussel parks, during the spring–summer and summer–autumn periods. At both sites, collectors were placed at a distance of 1 m from each other, from 5 to 14 m depth. The influence of season, site and depth on bivalve recruitment was inspected and the presence of invasive species was also evaluated. In all, 28 bivalve taxa were found, and a higher settlement rate was observed in summer–autumn compared to the spring–summer period. Mytilus galloprovincialis, Flexopecten glaber, Mimachlays varia and Aequipecten opercularis were the most abundant species in spring–summer. In the summer–autumn period, in both sites analysed, a very high quantity of Anadara transversa and F. glaber were found. Indeed, these species were dominant at Pellestrina and Caleri, respectively. Another non-indigenous species, Arcuatula senhousia, was also detected. Relevant amounts of Pectinidae spat, F. glaber in particular, were collected and the optimal depth range for the scallop spat collection was found to be between 8 and 14 m. Our results highlight the relevant potential of Pectinidae spat collection along the North-Western Adriatic coasts, even though the presence of invasive species needs to be monitored.

Data-Driven Recommendations for Establishing Threshold Values for the NIS Trend Indicator in the Mediterranean Sea

In the present work, we analysed time series data on the introduction of new non-indigenous species (NIS) in the Mediterranean between 1970 and 2017, aiming to arrive at recommendations concerning the reference period and provisional threshold values for the NIS trend indicator. We employed regression analysis and breakpoint structural analysis. Our results confirm earlier findings that the reference conditions differ for the four Mediterranean subregions, and support a shortening of the reporting cycle from six to three years, with a two-year time lag for the ensuing assessment. Excluding Lessepsian fishes and parasites, the reference period, defined as the most recent time segment with stable mean new NIS values, was estimated as 1997–2017 for the eastern Mediterranean, 2012–2017 for the central Mediterranean, 2000–2017 for the Adriatic and 1970–2017 for the western Mediterranean. These findings are interpreted primarily on the basis of a basin scale temperature regime shift in the late 1990s, shifts in driving forces such as shellfish culture, and as a result of intensified research efforts and citizen scientist initiatives targeting NIS in the last decade. The threshold values, i.e., the three-year average new NIS values during the reference period, are indicative and will ultimately depend on the choice of species and pathways to be used in the calculations. This is discussed through the prism of target setting in alignment with specific management objectives.

Harbour type and use destination shape fouling community and non-indigenous species assemblage: A study of three northern Tyrrhenian port systems (Mediterranean Sea)

Fouling communities were studied in three port systems of Northern Tyrrhenian Sea (Western Mediterranean), focusing on the occurrence of non-indigenous species (NIS). For each port system two harbour types (large port and recreational marina) were sampled and, within each large port, fouling samples were collected considering two use destinations (commercial and touristic harbour). Among the 431 taxa identified, forty-two were alien or cryptogenic, four of which were new records for the study area. Harbour type and use destination shaped fouling communities and NIS assemblages, with their relative influence varying among different port systems. High fouling variability was detected within port environments and between different marinas. NIS showed the highest occurrence in large ports, in which the touristic harbour generally hosted the greatest amount. Therefore, the touristic harbours within large ports were identified as susceptible areas for NIS establishment and their possible subsequent spread at local scale through recreational maritime traffic.

Ecological status assessment and non-indigenous species in industrial and fishing harbours of the Gulf of Gabès (central Mediterranean Sea)

Port Biological Baseline Surveys (PBBS) are standardized surveys of the indigenous and non-indigenous marine biodiversity within harbour activities. They provide a baseline for monitoring changes in the structure and function of harbour communities. This study conducted in 12 fishing and industrial harbours from January to December 2018 was the first initiative of a Port Baseline Survey aimed to assess the impact of biological invasions in harbours of the Gulf of Gabès (GG), Tunisia. A total of 174 macrobenthos species were recorded, belonging to eight phyla, with a dominance of crustaceans (32%), molluscs (31%) and polychaetes (20%). Among these species, 57 were non-indigenous species (NIS) for Tunisian waters, while 27 species were recorded for the first time in GG harbours, and three decapods (Dyspanopeus sayi, Hippolyte prideauxiana and Pilumnus minutus) and one amphipod (Hamimaera hamigera) were newly recorded from Tunisian waters. Two main categories of harbours are distinguished according to their macrobenthic communities and environmental conditions. The industrial harbours yield higher richness and abundance of NIS than the fishing harbours. The ALEX metric is used to evaluate the biological invasion status of the Gulf of Gabès harbours and shows that their status ranges from unaffected in fishing harbours to extremely affected in industrial harbours. Three biotic indices (AMBI, BO2A and BENTIX) are applied to assess the ecological status of harbours, which varies from moderate to good. ALEX and the other biotic indices are significantly correlated with harbour characteristics, maritime traffic and edaphic factors (organic matter and chemical contamination). The present study provides a data baseline for the implementation of environmental policies and management plans in the future.

Early detection of marine invasive species following the deployment of an artificial reef: Integrating tools to assist the decision-making process

Early detection and rapid response plans are a set of principles to reduce the establishment, spread and impact of invasive species and it is a critical step in management in marine ecosystems. Two potentially invasive ascidians attached to the hull of a recently sunk fishing vessel were early detected in Patagonia. With the aim of assisting in the management decision-making process during the early steps of a rapid response, we conducted several analyses through different approaches. First, we identified the species through classic taxonomical and genetic analyses. Then, we evaluated the regional and international shipping connectivity to study potential donor regions and finally, we used species distribution models (SDMs) to predict the potential distribution of these species. The potentially invasive ascidians were identified as Styela clava and Styela plicata, and this is the first record for both species in the Nuevo gulf, Patagonia Argentina. Both species have a widespread distribution around the world with strong ecological and economic impacts documented. Shipping traffic analysis suggested that S. plicata could have arrived by secondary spread from regional ports, while the arrival of S. clava was likely to be associated with international shipping traffic. Furthermore, the SDM predicted that S. clava has suitable coastal areas along the entire Southwestern Atlantic shoreline, where it is currently absent. On the contrary, the SDM predicted that further southward spread of S. plicata is unlikely, being limited by the minimum annual temperature. We discussed the different approaches, tools, and expertise integrated in this work in the light of the decision-making process for the early detection of marine invasive species in the Southwestern Atlantic. Moreover, we call attention to the increased creation of artificial habitats through the intentional sinking of ships and the potential consequences of these actions in the conservation of marine ecosystems.

Non-indigenous species in Mediterranean ports: A knowledge baseline

Port areas have been considered bioinvasion hotspots due to the concentration of several invasion vectors. However, the actual distribution of non-indigenous species (NIS) in Mediterranean ports is still poorly understood. Here we conducted a literature review with the aim to provide a knowledge baseline about NIS distribution in Mediterranean ports. NIS distribution in Mediterranean ports showed a high degree of heterogeneity in terms of studies across the whole basin, with a limited knowledge on both specific taxa and geographical areas, as well as a generally low proportion of investigated ports. The low rate of specific studies designed to monitor these particular environments may represent the main source of knowledge gaps. Mediterranean ports host NIS from all regions of the world, playing a key role in marine bioglobalization. Our synthesis represents the first baseline addressing the presence of NIS in Mediterranean ports, which may be useful to define plans of NIS management and strategies focusing on a network of recognised focal hotspots.

Macrozoobenthos in the Adriatic Sea ports: Soft-bottom communities with an overview of non-indigenous species

The present paper is a contribution to the first initiative of the Port Baseline Survey (PBS) for Non-indigenous species (NIS) in the Mediterranean Sea. It presents a report on the soft-bottom macrobenthos from the five Adriatic ports: Bari, Ancona (Italy), Koper (Slovenia), Pula, Rijeka (Croatia), with a focus on the presence and contribution of NIS to native assemblages. Out of 451 species identified, only four were common to all ports. A total of eight NIS were recorded, five in surveyed ports and three in the lagoon connected to the Port of Koper. The highest number of NIS was recorded in Bari, and the highest abundance in Ancona and Bari. Generally, the number, abundance and contribution of NIS seems too low to cause a substantial impact on native communities in surveyed ports. The suitability of methods adopted for PBS for soft-bottom NIS was discussed and suggestion for methodological improvement is provided.