WGEUROBUS – Working Group “Towards a EURopean OBservatory of the non-indigenous calanoid copepod Pseudodiaptomus marinUS”

Integrative approach to monitoring metazoan diversity and distribution in two Mediterranean coastal sites through morphology and organismal eDNA

Marine and coastal ecosystems respond to climate change in various ways, such as the type of ecosystem, the species composition, interactions, and distribution, and the effect of local stressors. Metazoan organisms, particularly zooplankton, are important indicators for monitoring the effects climate-driven warming in marine coastal ecosystems over the long term. In this study, the diversity and distribution of zooplankton communities in the Mediterranean Sea (Canyon Dohrn and LTER-MareChiara, Gulf of Naples), a known biodiversity and climate changes hotspot, have been assessed using the integration of morphological-based identification and organismal eDNA. Our findings showed that the multi-locus strategy including the mitochondrial cytochrome c oxidase I (COI) gene and the hypervariable region V9 of the 18S rDNA (18S V9) as targets, improved the taxonomic overview, with the COI gene being more effective than the 18S V9 region for metazoans at the species level. However, appendicularians were detected only with the 18S V9 region. Overall, organismal eDNA is a powerful approach for revealing hidden biodiversity, especially for gelatinous and meroplankton components, and provided new insights into biodiversity patterns. The ecological importance of calanoid copepods in coastal ecosystems has been confirmed. In contrast, the discovery of 13 new metazoan records in the Mediterranean Sea, including two non-indigenous copepod species, suggested that local stressors affect zooplankton community structure and resilience, highlighting the importance of biomonitoring and protecting marine coastal ecosystems.

SEASONAL AND INTERANNUAL DYNAMICS OF THE ABUNDANCE OF THE BLACK SEA ALIEN SPECIES <i>PSEUDODIAPTOMUS MARINUS</i> SATO, 1913 (COPEPODA, CALANOIDA, PSEUDODIAPTOMIDAE) IN THE CRIMEAN COASTAL WATERS: INFLUENCE OF THE TEMPERATURE FACTOR

Observation on the occurrence of the Black Sea alien species Pseudodiaptomus marinus were initiated since this species was reported in the coastal waters of Crimea, in 2016. Current study is focused on the 170-500 µm microplankton fraction represented by nauplii and the first copepodite stages. These data were complemented by the mesoplankton fraction abundance contributed by copepodite stages II-V and adults. Samples were collected by plastic bottles at the sea surface and by Juday and Apstein plankton nets in the upper 10 m layer. Nauplial stages of P. marinus were observed during the first three years after species invasion, in September, at the sea surface temperature range from 21.1 to 25.5 C. From 2019 to 2020, specimens appeared in July, at temperatures from 25.8 to 26.0C. The presence of specimens in samples has been observed by the end of November or December, at sea surface temperature of 13.1 or 8.6C, respectively. The maximal abundance was observed in the inner part of the Sevastopol Bay. The correlation value of 0.7-0.9 was estimated between the abundance and sea surface temperature throughout the year. Inter-annual variations of the abundance were associated with an integrative indicator of temperature (in particular, the sum of active temperatures).

First certain record of Demospongiae class (Porifera) alien species from the Mediterranean Sea

In this paper, we identify some sponge specimens collected in the Faro Lake in Sicily, and belonging to Haliclona (Halicoclona) by using morphological analysis accompanied by molecular analysis through amplification of several molecular markers (18S and 28S rRNA, CO1 and ITS). The samples are identified as. H. (Halichoclona) vansoesti de Weerdt, de Kluijver & Gómez, 1999, a species native to the Caribbean, and therefore this is the first record of an alien species of the Demospongiae class (Porifera) from the Mediterranean Sea. This presence can be ascribed as results of global change (mainly global warming) that are affecting marine environment.

Plankton diversity in Anthropocene: Shipping vs. aquaculture along the eastern Adriatic coast assessed through DNA metabarcoding

Coastal ecosystems globally are exposed to the most pervasive anthropogenic activities, caused by a suite of human infrastructure and enterprises such as shipping ports, aquaculture facilities, fishing, and tourism. These anthropogenic activities may lead to changes in ecosystem biodiversity, followed by loss of ecosystem functioning and services. Shipping industry and aquaculture have also been recognized as the main vectors for introduction of marine non-indigenous species (NIS) worldwide. In this study, we used DNA metabarcoding-based methods to investigate plankton biodiversity under varying anthropogenic pressures (shipping and bivalve aquaculture) along the eastern Adriatic coast (the northernmost part of the Mediterranean Sea). Our comparative assessment revealed similar community structures among investigated coastal locations (Northern, Central and Southern Adriatic). When the whole plankton communities were considered, they did not differ significantly between port and aquaculture sites. However, the proportion of the unique zOTUs in the port samples was remarkably higher than that in aquaculture sites (40.5% vs 8.2%), indicating that port areas may receive higher abundance and species richness of NIS than aquaculture sites. Further important difference between the two types of anthropogenically impacted habitats was a high abundance of three notorious invaders - M. leidyi, M. gigas, and H. elegans in late summer at the aquaculture site in Northern Adriatic. Therefore, the plankton community of the area is under pressure not only from aquaculture activities, but also establishment of NIS. Port areas are probably under greater introduction pressure from NIS, but aquaculture sites may experience greater community changes due to their establishment.

The non-indigenous Oithona davisae in a Mediterranean transitional environment: coexistence patterns with competing species

The Venice lagoon (VL) has been recognized as a hot spot of introduction of non-indigenous species (NIS), due to several anthropogenic factors and environmental stressors that combined may facilitate NIS invasions. In the last decades an increasing number of zooplankton NIS have been observed in the VL. This work aims to provide a picture of the annual cycle and distribution of the recently recorded non-indigenous copepod Oithona davisae, considering the coexistence patterns with the congeneric resident Oithona nana. Therefore, zooplankton samplings were carried out monthly from August 2016 to July 2017 at five Long-Term Ecological Research LTER stations in the VL. Oithona davisae showed a persistent occurrence throughout the year with the highest abundances in the warm season and in the inner areas, while the congeneric O. nana, showing a different distribution pattern, resulted more abundant near the inlets of the Lagoon, where O. davisae reached the minimum density. Oithona davisae seems to find local conditions that promote its settlement and distribution, especially in the inner and more trophic lagoon sites. In other European coastal embayments or transitional waters, O. davisae occupied the niche left by the indigenous O. nana or can replace this congeneric species through competitive exclusion mechanisms. Our data indicate that, for now, such species replacement has not occurred in the VL. One of the causes is the extreme variety of habitats and niches offered by this environment allowing a balanced coexistence with O. nana and in general with the resident copepod community.

Pseudodiaptomus marinus Sato, 1913 in the Black Sea: morphology, genetic analysis, and variability in seasonal and interannual abundance

Calanoid copepod Peudodiaptomus marinus Sato, 1913 was first recorded in Sevastopol Bay in the northern Black Sea in September 2016. We performed regular observations of this new invasive species between October 2016 and December 2018. We conducted bi-weekly plankton sampling at three stations located within or adjacent to Sevastopol Bay. This is the first paper to combine (i) a detailed morphological study, (ii) molecular genetic analysis, and (iii) an investigation of P. marinus seasonal dynamics and interannual abundance variability in the coastal Black Sea. Our morphological research showed similarities between Pseudodiaptomus specimens and existing P. marinus illustrations and descriptions. Our morphological analysis results were confirmed using molecular genetic studies. Based on the genetic variability of ITS2 and cytb, we found that all investigated specimens from Sevastopol Bay belonged to P. marinus. Investigations of P. marinus seasonal and interannual abundance variability showed the same seasonal patterns throughout the studied period, with a higher seasonal abundance from October to November and one pronounced density peak in autumn. The highest abundances (2,000 ind m^–3 at the mouth of the bay and more than 5,000 ind m^–3at its centre) were recorded in November 2018. In the samples, we found adults of both sexes, including ovigerous females, copepodites I–V, and nauplii, suggesting that the species reproduce in Sevastopol Bay. Our research indicated that P. marinus is a new non-indigenous species (NIS) in the Black Sea, and we will discuss a possible vector of its introduction into this basin.

Do plankton reflect the environmental quality status? The case of a post-industrial Mediterranean Bay

While the effects of industrial contamination in coastal areas may persist for years in benthos communities, plankton should not show permanent impairments because of their high spatial dynamics, fast turnover times and pronounced seasonality. To test this hypothesis, in 2019 we conducted five surveys in the Bay of Pozzuoli (Gulf of Naples, Mediterranean Sea), in front of a dismissed steel factory and in the adjacent inshore coastal waters. High seasonal variability was observed for bacteria, phytoplankton and mesozooplankton, whereas plankton spatial gradients were relatively smooth during each survey. Plankton biomass and diversity did not reveal any effects of past industrial activities not even at the innermost stations of the Bay, which however showed some signals of present anthropogenic pressure. Hydrodynamic and morphological features likely play a prominent role in maintaining a relatively good status of the plankton of the Bay, which hints at the relevance of coastal circulation and meteorological dynamics to revitalize areas impacted by human activities.