Number Of Non-indigenous Species Research Articles

Development and Succession of Non-Indigenous and Cryptogenic Species over Two Different Substrates in the Port of Alicante (Western Mediterranean)

Artificial structures act as points of entry for non-indigenous species (NIS) in port areas and may support higher abundance and richness of them. The studies about NIS are increasing, but studies focusing on the variations in temporal recruitment and ecological mechanisms are still scarce. Thus, the aim of this work was to determine the colonization and development of non-indigenous sessile fouling species over two types of substrates (electrolytic carbonated and steel) during 12 months of immersion in the Alicante harbor. The biofouling communities of both substrates were analyzed in terms of abundance and species richness by status (native, cryptogenic, and NIS), and NIS assemblages of both substrates were studied by means of multivariate analyses. In total, 53 different species were identified, 38 in steel (six NIS and six cryptogenic) and 50 in the carbonated substrate (six NIS and 10 cryptogenic). Most NIS were more abundant and diverse after 9 months of immersion and had a preference for carbonated substrates. Furthermore, most of them were positively correlated in both substrates (mainly in steel) and it is noted that the number of NIS in the port of Alicante is increasing as new records have been detected.

Contributions to the Flora of the Andaman and Nicobar Islands

The Andamans and Nicobars are two groups of islands, lying in the Bay of Bengal between the latitudes 6°41' and 13°41' North and longitudes 92°11’ and 94°00' East. The Andamans consist of 204 islands, while the Nicobars are made up of 22 islands.Geology, soil and climate of these islands are discussed. A brief resume of the botanical history of these islands is presented.The vegetation of the Andamans is classified into 1. Mangrove forests 2. Beach forortr 3. Evergreen forests, situated at lower elevations in alluvial land and valleys 4. Deciduous forests 5. Moist evergreen forests at higher elevations 6. Vegetation in cleared lands and open areas. In Nicobars the following types of vegetation are met with 1. Beach forests 2. Evergreen forests 3. Grass lands 4. Marine vegetation. The floristic composition of these vegetations is discussed in detail.A floristic analysis is presented. The approximate number of Phanerogamic species may, amount to 1000 and 700 for the Andamans and Nicobars respectively. The flora has been subjected to the influence of Burma and Malaysia. A number of non-indigenous species have intruded and mixed well with the Andaman flora. A third feature is presence of plants of their own, with a number of endemic species.

Diversity and dynamics of tintinnids communities from Romanian Black Sea, in 2021

Tintinnids are tiny ciliates from microzooplankton that are very important due to their implication in the microbial food web and for the fact that in the last two decades a considerable number of non-indigenous species have entered and acclimatized in the Black Sea basin. The paper presents the species diversity and dynamic of microzooplanktonic tintinnids’ abundance as a result of two cruises carried out in May-June and August-September 2021, along the Romanian Black Sea coast. We identified 23 tintinnid species in total, with a higher diversity in the surface layer compared to those of depth. The species Eutintinnus sp. and Salpingella decurtata were found eclusively in the 10 m layer. Tintinnopsis cylindrica represented 74% of the mean biomass of tintinnid’s community from May-June, the best quantitative representation recorded in the Romanian coast's northern sector. Amphorellopsis acuta represented 91% of the mean biomass of tintinnid’s community in August-September. The biotic component was also correlated with temperature and salinity to give more information regarding spatial and temporal variations from one area to the other. The findings contribute to the knowledge of microzooplankton communities in the Romanian Black Sea region. The data on species composition, abundance distribution, and environmental correlations enhance our understanding of the ecological dynamics and potential ecological implications of tintinnid communities. This study brings valuable information to the understanding of the microzooplankton component in the Black Sea ecosystem.

Multi-indicator ‘state space’ approach to assessing changes in shallow urban reef ecosystem health

Tracking changes in ecosystem health is an important objective for environmental managers, but is often limited by an understanding of what constitutes a “healthy” system and how to aggregate a range of health indicators into a single meaningful metric. We used a multi-indicator ‘state space’ approach to quantify changes over 13 years in reef ecosystem health in an urban area that has undergone intense housing development. Based on nine health indicators (macroalgal canopy length and biomass, macroalgal canopy and habitat functional diversity, mobile and predatory invertebrate density and size, total species and non-indigenous species richness), we found that the overall health of the reef community declined at five of the ten study sites. This decline was associated with a large collapse in the gastropod community, a shortening of macroalgal canopies and an increase in the number of non-indigenous species. While the cause of this decline and mechanisms responsible are not fully understood, the decline correlated with an increase in sediment cover on the reefs and warming ocean temperatures over the monitoring period. The proposed approach provides an objective and multifaceted quantitative assessment of ecosystem health that can be easily interpreted and communicated. These methods could be adapted to other ecosystem types to inform management decisions regarding future monitoring, conservation and restoration priorities to achieve greater ecosystem health.

Detection and monitoring of invertebrate non-indigenous species through DNA metabarcoding in a recreational marina of the Northwest of Portugal

In marine and coastal ecosystems, the proliferation of non-indigenous species (NIS) is among the top causes of biodiversity loss. Thus, it is essential to prevent the entrance and proliferation of NIS by detecting their presence as early as possible at the most susceptible locations, such as ports and marinas. Molecular techniques, like DNA metabarcoding, may be faster and more effective in the early detection of NIS. Its high sensitivity allows the detection of species at any stage of their life cycle and when present at very low densities. However, the detection power can be affected by the methodologies employed through the DNA metabarcoding analytical chain. This study aimed to assess the seasonal effects, sampling method (hard and artificial substrates, zooplankton and eDNA) and genetic marker (COI and 18S) in the recovery of NIS through DNA metabarcoding. Sampling was conducted in 3 seasons (spring, autumn, and winter of 2020/2021) in the “Porto Atlântico” marina, which is located near a major commercial port of the North of Portugal (Leixões). Overall, 626 species were identified through DNA metabarcoding, with the dominance of Crustacea, Ascidiacea and Mollusca. The sampling method and season significantly affected the marine invertebrate species recorded, for both molecular markers, with a high proportion of species detected exclusively using one method (7 to 20%). Overall, 31 NIS were detected, 7 of which are considered invasive and 6 are presumed new records in mainland Portugal. Zooplankton sampling and winter were, respectively, the method and the season where the highest number of NIS was detected, but the maximum number was only attained when pooling the results from all sampling methods and seasons. Our study highlights that different sampling methods and genetic markers, over different seasons, are needed to detect NIS in marine habitats, since the number of species shared by these factors is low.

How many Non-Indigenous Species occurring in the Mediterranean Sea can actually be identified through environmental DNA? A gap analysis of NIS DNA barcodes in the reference libraries

The Mediterranean Sea is known for hosting a high diversity of species, with more than 17,000 reported marine species, one fifth which are endemic. Moreover, the number of non-indigenous species (NIS) in the Mediterranean Sea is recently reported to be increasing. The monitoring and the distribution of NIS is a key requirement for the conservation and management of the ecosystems, as also foreseen by the regulation (EU) No 1143/2014 of the European Parliament and of the Council of 22 October 2014 on the prevention and management of the introduction and spread of invasive alien species. A promising innovative approach for the identification of species and biodiversity is the use of molecular tools (DNA barcoding and metabarcoding). Combined with environmental DNA (eDNA) extracted from environmental samples like water or sediment, traces of species can be identified. Currently, the main limitation in the use of molecular tools (DNA barcoding and metabarcoding, eDNA) for species identification is the incompleteness of the DNA barcode reference databases. We assessed the extent of gaps in DNA barcode reference libraries, using the most updated inventory of 666 confirmed alien species occurring in the Mediterranean Sea. Also, the availability of primers for the amplification process was investigated. 32.58% of these species lack DNA barcodes in the reference libraries. Also, 70% of the retrieved NIS in the DNA barcode libraries lack the public availability of the primers used for the amplification process. The results of this study allow us to direct scientific efforts towards specific taxonomic groups in order to complete the NIS DNA barcode reference libraries and enable effective application of eDNA in investigations of the occurrence and the distribution of NIS in the Mediterranean Sea, and in the first sighting of still unknown NIS.

Surveillance of non-indigenous invertebrate species through DNA metabarcoding in recreational marinas in the North and Center of Portugal

DNA metabarcoding has been widely used in biodiversity assessments as a complement to traditional morphology-based techniques. This technique is useful for the early detection and surveillance of non-indigenous species (NIS) in aquatic ecosystems. When introduced to new locations, NIS can establish, and become invasive, which may cause severe alterations to native ecosystems and biodiversity. As most introductions in coastal ecosystems occur by transport in ships (through ballast waters discharges and biofouling), ports and marinas are priority hubs for the early detection of NIS. The aim of this study was to survey marine invertebrate NIS in four marinas in the north and center of Portugal using (e)DNA metabarcoding and different sampling methodologies. We sampled four marinas in three locations in Portugal spanning a distance of ca. 150 km: one in Viana do Castelo (VC), one in Porto (L), inside the port of Leixões, and two in Aveiro (Av1: Costa Nova and Av2: Oudinot). Viana do Castelo, Porto, and Oudinot marinas are more sheltered, located near the coast, with a lower current flow, while Costa Nova marina is located inside a channel, more exposed to the passage of ships and to a higher current flow. Samples were taken of the organisms colonizing the marinas’ hard substrates (e.g., pontoons, buoys, ropes), as well as from water, for environmental DNA (eDNA) analysis, and zooplankton, collected using a 55-µm mesh net. We used two molecular markers: the mitochondrial cytochrome c oxidase gene (COI) and the small subunit ribosomal RNA gene (18S) to produce amplicon libraries for each sample, which were high throughput sequenced in an Illumina MiSeq platform. mBRAVE and SILVAngs were then used to process the sequence data and to generate species-level assignments for COI and 18S data, respectively. A total of 23 NIS was detected in this study: 13 using each molecular marker. Only 3 NIS were detected using both markers. The highest number of NIS was detected in the Av1 marina with COI (11), whereas in the other marinas this number ranged from 5-9 NIS depending on the molecular marker. Six NIS were common to all the marinas, amongst which Amphibalanus amphitrite and Amphibalanus eburneus, two invasive barnacle species and Eriocheir sinensis, the Chinese mitten crab, a very well-known species with invasive behavior that causes severe ecological and economic damages. Fifty percent of NIS belonged to the phyla Arthropoda: Crustacea and Chordata: Ascidiacea. The sampling method that registered the highest number of NIS (9) was the eDNA from water in Av1, using COI. Overall, 18S detected approximately 1,6 times higher numbers of OTUs (237-267), phyla (16-21) and species (179-210) than COI, and only 5-6% of species were detected using both markers. Regarding the type of sampling method, the zooplankton samples retrieved the highest number of phyla (20 in VC; COI: 12 and 18S: 20) and more species (40 to 155; COI: 90 and 18S: 155), namely from Mollusca and Annelida. Between the three methods, there were only 21 (COI) to 28% (18S) of shared species. Crustacea dominated most samples collected from hard substrates. As for marinas, VC had the highest number of recovered OTUs (267), phyla (21) and species (210), when analyzed with the 18S marker, and the lowest number of OTUs (94) and species (86) was recovered in Av1 with COI. Coincidently, this was also the marina with the highest number of NIS probably due to its more exposed location. These results show the efficiency of NIS detection using (e)DNA metabarcoding but reveal the need to employ different molecular markers and sampling methodologies to guarantee a more comprehensive surveillance and detection of NIS in these environments.

Assessment of the colonization and dispersal success of non-indigenous species introduced in recreational marinas along the estuarine gradient

• NIS are more tolerant to the environmental gradients than the native species. • There is a higher incidence of NIS in recreational marinas with higher salinity. • NIS successfully spread from the recreational marinas into neighboring areas. • Middle zone of the estuary seems to be more susceptible to secondary spread. The introduction of non-indigenous species (NIS) is considered as one of the main causes associated with biodiversity loss. The number of NIS has increased significantly emphasizing the need to know and manage the processes of biological invasions. Recreational marinas are points of entry for potential colonizers and can act as stepping-stones for the spread of these species. The main objectives of this work were to assess the distribution patterns of the fouling communities within recreational marinas in the Tagus estuary and to evaluate NIS dispersion ability. The fouling communities were assessed at four different recreational marinas and neighbouring hard substrate areas along the estuarine gradient of the Tagus estuary. The native communities of those recreational marinas showed a spatial gradient consistent with the estuarine gradient, with higher similarity between marinas with higher marine influence. A total of 14 NIS were identified within the recreational marinas but none occurred at the marina with higher freshwater influence. Although NIS distribution pattern reflected, to some extent, the estuarine gradient, there was a lower heterogeneity between locations when compared to native communities, evidencing a greater tolerance of NIS to a wider range of environmental conditions. Nine of the NIS identified at recreational marinas were also found in the neighbouring areas, suggesting their dispersal ability. NIS that seem to be able to disperse outside the marinas have planktonic larval stages and higher environmental tolerance, which seems to have contributed to the successful spread. These results emphasize the importance of monitoring NIS occurrence in recreational marinas in order to have an early warning on the arrival of species with higher invasion risks and to prevent its dispersal to sensitive ecosystems.

Citizen-science for monitoring marine invasions and stimulating public engagement: a case project from the eastern Mediterranean

The distribution of marine life has been alarmingly reshaped lately and the number of non-indigenous species and their impacts are rapidly escalating globally. Timely and accurate information about the occurrence of non-indigenous species are of major importance for the mitigation of the issue. However, still large gaps in knowledge about marine bioinvasion exist. Mediterranean Sea is among the most impacted ecoregions globally. In this work we present a comprehensive overview of the project “Is is Alien to you? Share it!!!” which monitors non-indigenous species in Greece and Cyprus with the help of citizen scientists. The goal of this work is to present this project as a case study in order to demonstrate how citizen science can substantially contribute to the monitoring of biological invasions. We compared the projects database with the databased of ELNAIS and EASIN, for discuss weaknesses and advantages and future steps for advancing the effort. In total 691 records of marine alien and cryptogenic species were collected in these 2 years from Greece and Cyprus, with the density of records reaching 20 observations per km2 in some locations. The project has contributed significantly in the assessment of descriptor D2 “Exotic Species” of the Marine Strategy Framework Directive, with 3 new species for Greece. Future steps should focus on training citizens to report less reported taxa and raising the awareness of all relevant stakeholders.

Role of commercial harbours and recreational marinas in the spread of non-indigenous fouling species

The role of commercial harbours as sink and source habitats for non-indigenous species (NIS) and the role of recreational boating for their secondary spread were investigated by analysing the fouling community of five Italian harbours and five marinas in the western Mediterranean Sea. It was first hypothesised that NIS assemblages in the recreational marinas were subsets of those occurring in commercial harbours. However, the data did not consistently support this hypothesis: the NIS pools of some marinas significantly diverged from harbours even belonging to the same coastal stretches, including NIS occurring only in marinas. This study confirms harbours as hotspots for marine NIS, but also reveals that numbers of NIS in some marinas is higher than expected, suggesting that recreational vessels effectively facilitate NIS spread. It is recommended that this vector of NIS introduction is taken into account in the future planning of sustainable development of maritime tourism in Europe.

Invasions in Marine Communities: Contrasting Species Richness and Community Composition Across Habitats and Salinity

While many studies of non-native species have examined either soft-bottom or hard-bottom marine communities, including artificial structures at docks and marinas, formal comparisons across these habitat types are rare. The number of non-indigenous species (NIS) may differ among habitats, due to differences in species delivery (trade history) and susceptibility to invasions. In this study, we quantitatively compared NIS to native species richness and distribution and examined community similarity across hard-bottom and soft-sediment habitats in San Francisco Bay, California (USA). Benthic invertebrates were sampled using settlement panels (hard-bottom habitats) and sediment grabs (soft-bottom habitats) in 13 paired sites, including eight in higher salinity areas and five in lower salinity areas during 2 years. Mean NIS richness was greatest in hard-bottom habitat at high salinity, being significantly higher than each (a) native species at high salinity and (b) NIS richness at low salinity. In contrast, mean NIS richness in soft-bottom communities was not significantly different from native species richness in either high- or low-salinity waters, nor was there a difference in NIS richness between salinities. For hard-bottom communities, NIS represented an average of 79% of total species richness per sample at high salinity and 78% at low salinity, whereas the comparable values for soft bottom were 46 and 60%, respectively. On average, NIS occurred at a significantly higher frequency (percent of samples) than native species for hard-bottom habitats at both salinities, but this was not the case for soft-bottom habitats. Finally, NIS contributed significantly to the existing community structure (dissimilarity) across habitat types and salinities. Our results show that NIS richness and occurrence frequency is highest in hard-bottom and high-salinity habitat for this Bay but also that NIS contribute strongly to species richness and community structure across each habitat evaluated.

A national checklist of marine Mollusca in Spanish waters

A checklist of marine Mollusca recorded in Spanish jurisdictional waters is presented, based on a thorough literature search and a limited input of recent field work. The list is detailed according to the five demarcations of the Marine Strategy Framework Directive (NOR, Spanish north coast; SUR, Spanish coast of the Gulf of Cádiz; ESAL, Strait of Gibraltar and Alboran Sea; LEBA, East coast of Spain and Balearic Islands; CAN, the Canary Islands). The list differentiates coastal species living from the supralittoral zone to the shelf break, deep-sea benthic or demersal species, and holoplanktonic species, and also distinguishes between non-indigenous species and species endemic to a particular demarcation. A total of 2466 marine Mollusca species have been reported from Spanish waters, of which 1126 are recorded only from waters surrounding the Iberian Peninsula, 498 are recorded from the Canaries only, and 842 are shared. That total number represents around 5.5% of the global marine molluscan richness. Shore and shelf species are the most numerous (1837), followed by deep-sea benthic species (490) and pelagic species (139), but the contribution of the deep-sea species is most noteworthy in NOR. All eight molluscan classes were represented, but solenogastres and scaphopods were notably more represented than usual in NOR. Species richness in SUR and ESAL was higher than would be expected from their areas, supporting the claim that Andalusian waters have an exceptionally diverse molluscan fauna. Thirteen species collected from INDEMARES cruises are here reported for the first time in Spanish waters. The species recorded in Spanish seas represent more than half of the 4340 species of Mollusca recorded within the scope of the European Register of Marine Species, making this the highest species count in European seas. The Canary Islands demarcation holds by far the largest number of endemic species (127), but special mention is needed regarding the ca. 20 species endemic to the Strait of Gibraltar, a highly anomalous chorotype in the marine realm. The number of non-indigenous species (38) is surprisingly low compared with that of species known in the Mediterranean Sea, amounting to hardly 1.5% of the total and supporting the view that a high number of native species tends to reduce invasion success. The list is seen as a much needed tool for the identification of priority areas for biodiversity conservation, but requires permanent attention and curating in order to remain up-to-date.

Long-term physical, chemical and biological changes in a small, urban estuary

The Diep River estuary, a small estuary in suburban Cape Town, South Africa, has been subject to disturbance for centuries. Several earlier studies have documented conditions in the system, providing baselines against which to measure more recent changes. This study: (i) describes major physical and hydrological changes that have occurred within this estuary; (ii) documents faunistic changes subsequent to earlier biological surveys; and (iii) provides an up-to-date faunal list. Salinity measurements and both invertebrate and fish samples were taken at five stations along the estuary in summer and winter 2014. A census of sandprawn Callichirus kraussi densities was also undertaken to compare with earlier surveys. Developments within the Diep River catchment and estuary have resulted in extensive changes in flow and salinity regimes, causing marked reductions in summer salinity levels, changes in frequency of mouth closure, and deteriorations in water quality. These have resulted in major changes in faunal composition and distribution, including an increase in numbers of non-indigenous species. Surveys in the early 1950s recorded 47 invertebrate species, whereas only 23 were found in 1974. A total of 23 species were again recorded in 2014, but these included several freshwater forms not previously reported, which had entered the system due to lowered salinity values, as well as new alien introductions. Only six of the 69 taxa recorded were reported by all three surveys. There have been substantial declines in sandprawn abundance, from 40 million in 1998 to just over 12 million in 2014. In all, 12 fish species were recorded in the 1950s, nine in 1974, but only five in 2014, including the newly detected invasive mosquito fish Gambusia affinis and the translocated tilapia Tilapia sparrmanii. Thus, only three of the original native fish species remain. Contrary to these losses, the present bird fauna appear to be more abundant and diverse than previously. Regular monitoring is recommended to obtain a clearer understanding of ongoing changes, and major management interventions will be needed if further degradation is to be prevented.

The Enlargement of the Suez Canal and Introduction of Non‐Indigenous Species to the Mediterranean Sea

The Suez Canal is one of the most important waterways in the world – during the last year 17,148 ships passed through the Canal – reducing emissions, saving time, and operating costs to shippers. The rapid increase in ship size from the “Post-Suezmax” (> 12,000 TEU) to the latest container vessels (> 19,000 TEU) now requires enlargements of port facilities and canals. A project of this magnitude, and with potentially negative environmental outcomes, requires a transparent and scientifically sound “Environmental Impact Assessment” (EIA). An explicit obligation on Parties to the Convention on Biological Diversity (https://www.cbd.int/doc/ legal/cbd-en.pdf) was made to consider transboundary impacts on biodiversity, particularly those associated with invasive non-indigenous species. Although a nonbinding instrument, the “Rio Declaration on Environment and Development” sets forth important principles of international environmental law (UN 1992): States are responsible for ensuring that activities within their jurisdiction do not damage the environment of other States, and EIA, as a national instrument, shall be undertaken for proposed activities that are likely to have a significant adverse impact on the environment. To our knowledge, no Environmental Impact Assessment has been

The effects of city–suburb–exurb landscape context and distance to the edge on plant diversity of forests in Wuhan, China

We analysed the relative role of landscape context (city, suburb and exurb) and distance to the edge (from forest edge to 45 m in interior) on plant diversity of natural forests in Wuhan city. The results indicated that landscape context had significant effects on plant diversity, and both landscape context and distance to the edge affect vegetation and disturbance characteristics. Landscape context was the main factor affecting richness of woods, herbs, indigenous species, forest generalists and insect or wind pollination species. These species tended to be higher in exurban forests while non-indigenous species were higher in the urban forests. The number of non-indigenous species, forest specialists, herbs and insect pollination species also depended on distance to the edge or on both interactions. Richness of non-indigenous species decreased with increasing distance to the edge in urban forest. Vegetation characteristics that shrub cover was lower and disturbance characteristics that disturbed cover and human activity were higher in the urban edge than in the suburb and exurb edge, which decreased from the edge to the interior. Therefore, we should prioritize the preservation of less disturbed and frequented forests (suburban and exurban) to buffer the invasion of non-indigenous species, and to reserve more indigenous species.

Role of top-down and bottom-up forces on the invasibility of intertidal macroalgal assemblages

Despite the available information regarding the negative effects of non-indigenous species (NIS) on ecosystem structure and functioning, the mechanisms controlling NIS invasion remain poorly understood. Here, we investigated the relative roles of top-down and bottom-up control on the invasion of intertidal macroalgal assemblages by the macroalga Sargassum muticum (Yendo) Fensholt. Using a factorial experiment, nutrient availability and intensity of herbivory were manipulated along an intertidal rocky shore. We found that early recruitment of S. muticum was enhanced by low nutrient enrichment but no effect of grazers was observed. In contrast, at the end of the experiment (9-months after invasion) top-down control, together with the number of NIS and the percentage cover of ephemerals, was a significant predictor for the invasion success of S. muticum. In addition, both top-down and bottom-up forces played a significant role in structuring macroalgal assemblages, which indirectly could have influenced invasion success. Hence, by shaping community structure, main and interactive effects of bottom-up and top down forces may indirectly act on invasion. Our study highlights the importance of the recipient community structure on the invasion process and emphasizes the specific regulation of top-down and bottom-up forces in different stages of S. muticum invasion.

Country characteristics and non-indigenous species

ABSTRACTThis paper presents an econometric test of two hypotheses underlying the occurrence of non-indigenous species (NIS) at the global scale: openness of recipient nations which allows for international trade to act as a vector of NIS, and habitat fragmentation in recipient nations which facilitates establishment of introduced NIS. Explorative econometric methods have been utilised that combine the analysis of dimensionality with subset variable selection and multiple linear regression. Both NIS hypotheses are thereby supported, although slightly different in the cases of the mainland and island nations. It is concluded that expressions of openness have a larger impact on the number of NIS per unit territorial area in the mainland nations, whereas biota variables play a more dominant role in the case of the island nations. It is also concluded that different expressions of NIS occurrence affect the result, where NIS per area unit facilitates excellent explanatory performance.

Non-indigenous marine macroalgae in native communities: a case study in the British Isles

It has traditionally been considered that areas with high natural species richness are likely to be more resistant to non-indigenous species than those with lower numbers of species. However, this theory has been the subject of a debate over the last decade, since some studies have shown the opposite trend. In the present study, a macroalgal survey was carried out at 24 localities in Northern Ireland and southern England, using a quadrat approach in the lower littoral. The two opposing hypotheses were tested (negative versus positive relationship between native and non-indigenous species richness) in this marine environment. The effect of the presence of ‘impacts’, potential sources of disturbance and species introduction (e.g. marina, harbour or aquaculture), was also tested. A positive relationship was found between the number of non-indigenous species and the native species richness at the three different scales tested (quadrats, sites and localities). At no scale did a richer native assemblage appear to restrict the establishment of introduced species. The analyses revealed greater species richness and different community composition, as well as more non-indigenous species, in southern England relative to Northern Ireland. The presence of the considered impacts had an effect on the community composition and species richness in southern England but not in Northern Ireland. Such impacts had no effect on the non-indigenous species richness in either area.

Free-living benthic marine invertebrates in Chile

A comprehensive literature review was conducted to determine the species richness of all the possible taxa of free-living benthic marine invertebrates in Chile. In addition, the extent of endemism to the Pacific Islands and deep-sea, the number of non-indigenous species, and the contribution that the Chilean benthic marine invertebrate fauna makes to the world benthic marine invertebrate fauna was examined. A total of 4,553 species were found. The most speciose taxa were the Crustacea, Mollusca and Polychaeta. Species richness data was not available for a number of taxa, despite evidence that these taxa are present in the Chilean benthos. The Chilean marine invertebrate benthic fauna constitutes 2.47 % of the world marine invertebrate benthic fauna. There are 599 species endemic to the Pacific Islands and 205 in the deep-sea. There are 25 invasive or non-indigenous species so far identified in Chile. Though the Chilean fauna is speciose there is still a considerable amount of diversity yet to be described, particularly amongst the small bodied invertebrates and from the less well explored habitats, such as the deep-sea.

Pollution reduces native diversity and increases invader dominance in marine hard‐substrate communities

ABSTRACTAnthropogenic disturbance is considered a risk factor in the establishment of non‐indigenous species (NIS); however, few studies have investigated the role of anthropogenic disturbance in facilitating the establishment and spread of NIS in marine environments. A baseline survey of native and NIS was undertaken in conjunction with a manipulative experiment to determine the effect that heavy metal pollution had on the diversity and invasibility of marine hard‐substrate assemblages. The study was repeated at two sites in each of two harbours in New South Wales, Australia. The survey sampled a total of 47 sessile invertebrate taxa, of which 15 (32%) were identified as native, 19 (40%) as NIS, and 13 (28%) as cryptogenic. Increasing pollution exposure decreased native species diversity at all study sites by between 33% and 50%. In contrast, there was no significant change in the numbers of NIS. Percentage cover was used as a measure of spatial dominance, with increased pollution exposure leading to increased NIS dominance across all sites. At three of the four study sites, assemblages that had previously been dominated by natives changed to become either extensively dominated by NIS or equally occupied by native and NIS alike. No single native or NIS was repeatedly responsible for the observed changes in native species diversity or NIS dominance at all sites. Rather, the observed effects of pollution were driven by a diverse range of taxa and species. These findings have important implications for both the way we assess pollution impacts, and for the management of NIS. When monitoring the response of assemblages to pollution, it is not sufficient to simply assess changes in community diversity. Rather, it is important to distinguish native from NIS components since both are expected to respond differently. In order to successfully manage current NIS, we first need to address levels of pollution within recipient systems in an effort to bolster the resilience of native communities to invasion.