Investigating the cryptogenic status of the sea squirt Didemnum perlucidum (Tunicata, Ascidiacea) in Australia based on a molecular study of its global distribution

Didemnid species are assessed as species with a high invasive potential for Australia and as such are listed as target species for both state and national monitoring programs. The presence of the sea squirt Didemnum perlucidum (Monniot, 1983) was first documented in Australia in 2010 and has since then been detected extensively throughout the state of Western Australia and in the Northern Territory. These detections have raised important questions as to the origin and potential impact of this species in Australia. The current study was initiated to review the current known global geographic range of D. perlucidum and to obtain specimens that could support molecular studies aimed at evaluating the potential origin of this species in Australia. Characterization of 5’ COI mitochondrial sequences from 286 specimens revealed a remarkably low level of genetic diversity across the current known range of D. perlucidum and the existence of one main widespread genetic haplotype. Such findings suggest that all locations sampled in this study may in fact represent introductions of D. perlucidum and that the natural native range of the species remains unknown. Our demonstration that specimens (n=187) originating from across a broad expanse of the Australian West Coast were comprised of a single haplotype also lends support to the hypothesis that D. perlucidum is a species that has been introduced recently into Australia. This hypothesis is supported by the fact that D. perlucium distribution in Australia is mostly confined to artificial structures, it has displayed invasive characteristics, and its presence is now being detected across an increasingly wide geographical area. Given the demonstrated low level of genetic COI variation across its known global distribution, lack of clarity around its native range, and limited availability of data on this species globally, we recognize the requirement for further work to more fully elucidate the exact origins and patterns of distribution of D. perlucidum in Australia. This study represents the most comprehensive mapping of the current global distribution of D. perlucidum conducted to date and will hopefully motivate further studies aimed at elucidating this species biology, origin, high-risk routes and impacts

Investigating the cryptogenic status of the sea squirt Didemnum perlucidum (Tunicata, Ascidiacea) in Australia based on a molecular study of its global distribution

Didemnid species are assessed as species with a high invasive potential for Australia and as such are listed as target species for both state and national monitoring programs. The presence of the sea squirt Didemnum perlucidum (Monniot, 1983) was first documented in Australia in 2010 and has since then been detected extensively throughout the state of Western Australia and in the Northern Territory. These detections have raised important questions as to the origin and potential impact of this species in Australia. The current study was initiated to review the current known global geographic range of D. perlucidum and to obtain specimens that could support molecular studies aimed at evaluating the potential origin of this species in Australia. Characterization of 5’ COI mitochondrial sequences from 286 specimens revealed a remarkably low level of genetic diversity across the current known range of D. perlucidum and the existence of one main widespread genetic haplotype. Such findings suggest that all locations sampled in this study may in fact represent introductions of D. perlucidum and that the natural native range of the species remains unknown. Our demonstration that specimens (n=187) originating from across a broad expanse of the Australian West Coast were comprised of a single haplotype also lends support to the hypothesis that D. perlucidum is a species that has been introduced recently into Australia. This hypothesis is supported by the fact that D. perlucium distribution in Australia is mostly confined to artificial structures, it has displayed invasive characteristics, and its presence is now being detected across an increasingly wide geographical area. Given the demonstrated low level of genetic COI variation across its known global distribution, lack of clarity around its native range, and limited availability of data on this species globally, we recognize the requirement for further work to more fully elucidate the exact origins and patterns of distribution of D. perlucidum in Australia. This study represents the most comprehensive mapping of the current global distribution of D. perlucidum conducted to date and will hopefully motivate further studies aimed at elucidating this species biology, origin, high-risk routes and impacts

Looks can be deceiving:Didemnum pseudovexillumsp. nov. (Ascidiacea) in European harbours

A strongly divergent lineage, putatively a new cryptic species, of colonial ascidian was first detected as an anomalous sample in a population genomics study of the well-known worldwide invasive species Didemnum vexillum Kott, 2002. This putative new taxon, found in a marina in Roscoff, France, is indistinguishable from Didemnum vexillum in the external aspect and coexists with it in syntopy. However, morphological characters such as spicules and larvae allow a clear-cut distinction. In accordance with the preliminary results based on genome-wide analyses, morphological traits and mitochondrial sequences of the cytochrome oxidase I gene both support the establishment of a new species Didemnum pseudovexillum sp. nov. Previous unidentified sequences in public databases showed that the new species is also present in NW Mediterranean marinas. Didemnum pseudovexillum sp. nov. is assigned for the time being a cryptogenic species status, although its presently known disjoint distribution across two biogeographic regions and its presence in ports are suggestive of an introduced species. Further studies should be performed to ascertain its current distribution and putative natural range and settle its native vs. non-native status. This finding casts doubts on previous reports of Didemnum vexillum and also calls for caution when performing fast field surveys of non-indigenous species such as rapid assessment surveys (RAS) or BioBlitz surveys, based solely on external characters

The highly competitive ascidian Didemnum sp. threatens coral reef communities in the Wakatobi Marine National Park, Southeast Sulawesi, Indonesia

Coral reefs in the Wakatobi Marine National Park (WMNP), Indonesia, are protected but have been degrading in several areas due to local anthropogenic stressors. In affected areas, benthic surveys revealed the occurrence of a dominant ascidian species of the genus Didemnum, which may negatively impact the benthic community composition and structure. We quantified the abundance, substrate preference, and growth rate of Didemnum sp. in non-degraded and degraded reefs to assess its impact on the benthic community. While Didemnum sp. occurred in similar high abundances in both, non-degraded (0.66%) and degraded (0.75 %) reef sites, this species showed a substantially (>10-fold) increased growth rate in degrading reefs (2.7 ± 0.98% day−1 increase in colony size, compared to 0.17 ± 0.39 % day −1 in non-degraded reefs). Furthermore, Didemnum sp. colonized many different substrates and showed the ability to overgrow live corals quickly. These observations indicate that Didemnum sp. can be a severe threat to a reef community by outcompeting live corals and call for further studies on the interaction between environmental pollution and Didemnum growth patterns in coral reefs

Environmental DNA Based Surveillance for the Highly Invasive Carpet Sea Squirt Didemnum vexillum : A Targeted Single-Species Approach

Funding Information: The authors would like to thank the site operators, owners and Solway Firth Partnership for allowing access and sample collection at studied sites visited during this study. Thanks also to Frank Armstrong, Katy Beaton, Maria Campbell, Pablo Dias, James Dooley, Judith Horrill, Nial McLeod, Warren Murray, Andrea Taylor, Joe Triscott, and Bill Turrell for contributing to field work and sample collection. The authors thank National Museums Scotland and particularly Fiona Ware for the loan of reference material (specimen register number NMS.Z.2015.82.8, 9 and 14 and NMS.Z.2018.2.2) which was used in the present study. KS thank the Japan Society for the Promotion of Science for post-doctoral fellowship funding.Peer reviewedPublisher PD

Distribuição e impacto de espécies incrustantes na maricultura de Santa Catarina

Orientadora: Profa. Dra. Rosana M. da RochaDissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Biológicas, Programa de Pós-Graduação em Ecologia e Conservação. Defesa : Curitiba, 30/09/2021Inclui referênciasResumo: A maricultura é responsável tanto pela introdução intencional de espécies não nativas para fins comerciais, como por fornecer substrato para espécies epibiontes/incrustantes introduzidas, que podem reduzir a qualidade dos bivalves e causar a depreciação de equipamentos (boias, cordas, embarcações, etc.). Neste sentido, o Capítulo I e II apresentam uma lista de espécies-alvo com resultados de levantamentos de distribuição, frequência e do impacto das incrustações, realizados em oito fazendas de mexilhões nos municípios de maior produtividade em Santa Catarina. Styela plicata foi a espécie mais difundida e ocorreu em mais de 70% de todos os substratos avaliados em cada local. De norte a sul, outras espécies muito frequentes (> 50% dos substratos) foram Megabalanus coccopoma, Aplidium accarense e Didemnum perlucidum na Penha, Schizoporella errata em Governador Celso Ramos, Branchiomma luctuosum e M. coccopoma em Palhoça e Florianópolis. As espécies-alvo eram geralmente mais frequentes em boias do que em long-lines, e as principais espécies incrustantes eram M. coccopoma, S. plicata e S. errata. Já nas pencas de mexilhões, S. plicata (98% das pencas), B. luctuosum, M. coccopoma, S. errata (>50%) e D. perlucidum (40%). Também descobrimos que os mexilhões eram 19-36% menores em tamanho e até 60% mais leves quando recobertos pelas espécies D. perlucidum, M. coccopoma e/ou S. errata, mas, considerando a classificação de impacto, Mytilus galloprovincialis classificou-se com maiores impactos negativos para os produtores. Mytilus foi introduzido recentemente em Santa Catarina e tem causado prejuízos sem precedentes à produção na região de Bombinhas. O monitoramento do mexilhão invasor e de Perna perna em Bombinhas, ao longo de um ano, revela que o recrutamento é sazonal e semelhante ao longo do ano, tornando impossível evitar a espécie invasora nos coletores de Perna. Análises moleculares apontam para a possibilidade de um único evento de introdução e o Mar Mediterrâneo como a região de origem dos indivíduos introduzidos no estado. No Capítulo final desta tese, apresentamos um estudo do potencial da maricultura de Santa Catarina em tornarse fonte de propágulos de espécies incrustantes para outras regiões do país. Considerando dois cenários representativos de emissões de gases do efeito estufa, descobriu-se que as áreas de habitat com alta adequabilidade ambiental permanecem no futuro (2040-50). Os estados de Pernambuco e Ceará, estão em maior risco devido à alta adequabilidade às espécies D. perlucidum e M. coccopoma e conectividade relativamente maior apontada pelo volume de cargas recebido em navios de contêineres saindo de Santa Catarina.Abstract: Mariculture is responsible both for the intentional introduction of non-native species for commercial purposes, as well as for providing substrate for introduced epibiont/fouling species, which can reduce the quality of bivalves and cause depreciation of equipment (buoys, ropes, vessels, etc.). In this sense, Chapter I and II present a list of target species with results of the distribution and frequency survey, carried out in eight mussel farms in the municipalities with higher productivity and estimates of species impact in southern Brazil. The ascidian Styela plicata was the most widespread species and occurred in more than 70% of all substrates evaluated at each site. From north to south, other very frequent species (> 50% of substrates) were the barnacle Megabalanus coccopoma and the ascidians Aplidium accarense and Didemnum perlucidum in Penha, the bryozoan Schizoporella errata in Governador Celso Ramos, the polychaete Branchiomma luctuosum and M. coccopoma in Palhoça and Florianópolis. The target species were usually more frequent on buoys than on long-lines, and the main fouling species were M. coccopoma, S. plicata and S. errata. Fouling mussel socks were S. plicata (98% of the socks), B. luctuosum, M. coccopoma, S. errata (>50%) and D. perlucidum (40%). We found that mussels were 19-36% smaller in size and weighed 60% less when covered by species D. perlucidum, M. coccopoma and/or S.errata but, considering the impact classification, Mytilus galloprovincialis ranked higher in the negative impacts to the producers. Mytilus was recently introduced in Santa Catarina and has caused unprecedented damage to production in Bombinhas. The monitoring of the invasive mussel and Perna perna in Bombinhas, over the course of one year, reveals that similar trends in seasonal recruitment makes it impossible to avoid the invasive species in Perna collectors. Molecular analyses point to the possibility of a single introduction event and the Mediterranean Sea as the region of origin of the individuals introduced into the state. In the final Chapter of this thesis, we present a study on the potential of Santa Catarina mariculture becoming a source of propagules of fouling species to other regions of the country. Considering two representative scenarios of greenhouse gas emissions, we found that habitat areas with high suitability remain in the future (2040-50). The states of Pernambuco and Ceará are at greater risk due to the high environmental suitability to the species D. perlucidum and M. coccopoma and connectivity indicated by the volume of goods transported in container ships with Santa Catarina as port of call

Avaliação global do risco de invasão de ascídias (Chordata:Tunicata) utilizando modelagem de nicho

Orientador : Profª. Drª. Rosana Moreira da RochaTese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Biológicas, Programa de Pós-Graduação em Ecologia e Conservação. Defesa: Curitiba, 04/11/2016Inclui referências : f. 46-58Área de concentraçãoResumo: Os ecossistemas podem ser transformados pelas espécies invasoras que causam tanto perdas ecológicas, quanto econômicas. Ascídias são invertebrados sésseis e seus representantes são modelos importantes para o estudo de dinâmicas de introduções. Estes organismos são abundantes em substratos artificiais e possuem larvas de curta duração, impossibilitando transpor grandes distâncias geográficas. Portanto, a dispersão transoceânica geralmente depende do transporte humano. Além disso, introduções recorrentes são comuns, aumentando o risco de invasão. Análises de risco que avaliem a probabilidade de organismos de portos doadores sobreviverem em portos receptores permitem antecipar medidas mitigatórias. Apresentamos uma avaliação, considerando dezenove espécies-alvo (algumas consideradas invasoras de preocupação global), utilizando como ferramenta a modelagem de distribuição de espécies baseada no nicho (MNE). A MNE consiste na combinação de variáveis ambientais e registros de presença (ocorrência) de espécies para parametrizar modelos de previsão de locais adequados à sobrevivência das espécies. Neste estudo testamos um conjunto de algoritmos (Random Forest - RF, Support Vector Machine - SVM e MaxEnt) por sua habilidade de predição, validamos utilizando medidas independentes (area under the curve - AUC) e dependentes do limiar (true skill statistics - TSS). As variáveis ambientais utilizadas na análise foram temperatura oceânica superficial, salinidade e clorofila a. Os três algoritmos foram bem sucedidos para as espécies (TSS>0,4) e os valores AUC para os conjuntos de modelos para cada espécie apresentaram pouca variação (AUC>0,7). Os modelos finais obtidos a partir do ensemble destes três algoritmos mostraram que existem condições ambientais para a expansão da distribuição de todas as espécies avaliadas em novas áreas de introdução. Considerando a adequabilidade ambiental e a conectividade entre áreas doadoras e receptoras através de rotas comerciais marítimas, foi possível determinar que as áreas mais vulneráveis à invasão pelas espécies estudadas foram o Atlântico sudoeste e o Pacífico nordeste. Regiões bastante invadidas como o Atlântico noroeste e o Mediterrâneo ainda comportam possibilidade de expansão regional das populações já conhecidas. Testando uma combinação de algoritmos informamos áreas que devem ser priorizadas para o monitoramento de futuras introduções e áreas em que medidas imediatas no controle populacional de espécies já estabelecidas devem ser tomadas devido ao risco de expansão de sua distribuição.Abstract: Ecosystems can be transformed by invasive species that cause both ecological and economic losses. Sea squirts are sessile invertebrates and their representants are important models for the study of issues on introduction dynamics. These organisms are abundant in artificial substrates and have short life span larvae, making it impossible to transpose large geographic distances. Therefore, the transoceanic dispersion generally depends on the human transport. In addition, oftentimes introductions are common issues, increasing the risk of invasion. Risk assessments on the likelihood of donors ports species survive in recipients ports allow anticipate mitigation measures. We present an evaluation considering nineteen target species (some considered invasive of global concern), using distribution modeling based on the niche of species as tool (ENM). The ENM is the combination of environmental variables and presence records (occurrence) of species to parameterize forecasting models of suitable sites for species survival. This study tested a set of algorithms (Random Forest - RF, Support Vector Machine - SVM and MaxEnt) for its predictive ability, validated using independent (area under the curve - AUC) and dependent threshold measurements (true skill statistics - TSS). Environmental variables used in the analysis were sea surface temperature, salinity and chlorophyll a. The three algorithms produced good predictions for the species (TSS> 0.4) and AUC values for each species showed little variation (AUC> 0.7). The final model obtained from the ensemble of these three algorithms showed environmental conditions for the expansion of distribution of all species assessed and new suitable áreas for introductions. Considering the environmental suitability and connectivity between donor and recipient areas through maritime trade routes, it was determined that the areas most vulnerable to invasion by species studied were the Southwest Atlantic and Northeast Pacific. Regions often invaded as the Northwest Atlantic and the Mediterranean also contain possibility of regional expansion of known populations. Testing a combination of algorithms we reported areas that should be prioritized for monitoring future issues and areas where immediate action on population control of already established species should be taken because of the risk of expansion of its distribution given its environmental suitability

Biodiversidade Da Comunidade Bêntica De Ambientes Rochosos Na área Marinha Protegida De Currais, Sul Do Brasil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)This study describes the biodiversity of benthic invertebrates on hard substrates in the Currais Marine Protected Area (Currais MPA), in the state of Paraná. The benthic community was sampled during 2012 to 2015, in winter and summer, at two islands and four groups of artificial reefs (ARs). Samples were collected along shallow (2-4 m) and deep (6-8 m) transects at the islands and ~18 m transects at the ARs. We also searched the literature to review all published records of benthic invertebrates on hard substrates in the Currais MPA. We recorded 176 taxa in the phyla Annelida (class Polychaeta), Arthropoda (class Maxillopoda, order Sessilia), Bryozoa, Cnidaria, Chordata (class Ascidiacea), Echinodermata, Mollusca and Porifera, in 13 classes, 40 orders and 75 families. With these 102 new records, our list comprises 58% of all recorded species. Of these, 58 taxa were first records for the state of Paraná. This remarkable number of new records highlights that biodiversity studies are lacking in Paraná. Fifteen non-indigenous species and one endangered species, the sea star Coscinasterias tenuispina (Lamarck, 1816), are included. This is an important transitional area to monitor expansion or constriction of the latitudinal distributions of species, in the context of climate change, that may influence the geographical distribution of species (both native and invasive). This study is the first inventory of marine hard substrate habitats of the Currais MPA with a surprisingly diverse community. © 2016, Universidade Estadual de Campinas UNICAMP. All rights reserved.164305201/2014-0, CNPq, Conselho Nacional de Desenvolvimento Científico e TecnológicoConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Bacteria associated with tunicate, Polycarpa aurata, from Lease Sea, Maluku, Indonesia exhibiting anti-multidrug resistant bacteria

Bacteria associated with tunicate, Polycarpa aurata, from Lease Sea, Maluku, Indonesia exhibiting anti-multidrug resistant bacteria. Biodiversitas 20: 956-964. Tunicate is a rich secondary metabolites producer with various biological activities whether as an original producer or produced by the associated microorganisms. In this study, a total of 11 tunicate specimens were identified as Polycarpa aurata with four color variations based on morphological characteristic and COI gene identification and BLAST analysis. The P. aurata associated-bacteria were isolated and tested for antimicrobial activity against multi-drug resistant (MDR) bacteria. A total of 86 axenic isolates were successfully purified. Furthermore, nine isolates (10.5%) exhibited antibacterial activity on preliminary screening. Nine prospective isolates were fermented in respective medium (Zobell 2216, modified M1 or modified ISP2 media) then extracted using ethyl acetate. The ethyl acetate extracts from liquid fermentation were tested against MDR Escherichia coli, MDR Bacillus cereus, Methicillin-Resistant Staphylococcus aureus (MRSA) and Methicillin-Sensitive and Staphylococcus aureus (MSSA). As a result, seven isolates (8.1%) still retained the activity at the extract concentration 150 µg/disk. Molecular analysis based on 16S rDNA sequencing revealed the most active isolates, TSB 47, TSC 10 and TSB 34 identified as Bacillus tropicus, Vibrio alginolyticus and Virgibacillus massiliensis, with BLAST homology 99%