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Ballast water discharges may cause negative impacts to aquatic ecosystems, human health and economic activities by the introduction of potentially harmful species. Fifty untreated ballast water tanks, ten in each port, were sampled in four Adriatic Italian ports and one Slovenian port. Salinity, temperature and fluorescence were measured on board. Faecal indicator bacteria (FIB), phyto- and zooplankton were qualitatively and quantitatively determined to identify the species assemblage arriving in ballast water. FIB exceeded the convention standard limits in 12% of the sampled tanks. Vibrio cholerae was not detected. The number of viable organisms in the size groups (minimum dimension) <50 and ≥10 μm and ≥50 μm resulted above the abundances required from the Ballast Water Management Convention in 55 and 86% of the samples, respectively. This is not surprising as unmanaged ballast waters were sampled. Some potentially toxic and non-indigenous species were observed in both phyto- and zooplankton assemblages. • Ballast water sampling was carried out on 50 ships in five Adriatic ports. • Vibrio cholerae was not detected. • Viable organisms were detected in >90% of ballast tanks. • Six potentially harmful and one non-indigenous phytoplankton species were identified. • Six non-indigenous zooplankton species were observed. [ABSTRACT FROM AUTHOR]

Monstrilloid copepods collected during zooplankton surveys carried out over several years (2009-2016) in the Gulf of Trieste, northern Adriatic Sea, were examined. A total of seven species were found, of which six are undescribed, five of Cymbasoma and one of Monstrilla. These new species are described, illustrated and compared herein with its known congeners. Two of them are related to the C. rigidum species complex. One of these species is described based on both the male and the female; sexes were linked by identical details of the cephalic structure and the antennulary armature. Two previous reports of females attributed to C. tumorifrons from the Mediterranean relate to specimens that in fact belong to a new species, C. mediterranea. The most abundant species was M. grandis, which had a remarkable aggregation around the Trieste harbour in 2015. Male and female specimens of this assumedly widespread species were examined and the observed intra-specific morphological variability is reported and compared with previous illustrated reports; this nominal species probably this nominal species, probably represents a species complex. The addition of the new species here described brings the number of nominal species in the Mediterranean-Black Sea region to 26. [ABSTRACT FROM AUTHOR]

Mesozooplankton community composition at the species/taxa level was investigated from January to December 2001, at eight stations in the northern Adriatic Sea. Annual dynamics, taxonomic composition and spatial diversity in relation to different trophic conditions are discussed as related to previous studies and to different conditions, such as the presence of mucilage events. Zooplankton communities all over the northern sub-basin were dominated by the cladoceran Penilia avirostris in summer, and by the calanoids Paracalanus parvus, Acartia clausi and the poecilostomatoids Oncaea spp. during the rest of the year. Whereas coastal communities were more variable with time and location, we were able to identify a group of offshore stations with a similar species/taxa composition and annual dynamics. Comparing the present results with previous studies, we observed significant changes in community composition in the time scale of 20 years, mostly due to a general decrease of A. clausi as the dominant species, being replaced by P. parvus. Also, P. avirostris swarms appear to have extended their temporal occurrence, and were present for longer periods of time when compared to past records. These changes might be related to the observed general increase of the average sea water temperature in the northern Adriatic Sea. [ABSTRACT FROM AUTHOR]

The first ‘bloom’ of Noctiluca scintillans in the Northern Adriatic Sea was recorded in 1977. The organism caused several red tides in the whole basin during the late 1970s, a period characterized by increasing nutrient loads. During the 1980s and early 1990s, there was no ‘red tide’, but the species was an almost constant summer presence, associated with high temperatures. Noctiluca scintillans was almost completely absent from 1994 until May 1997, concurrent with a general plankton decrease. From summer 1997, N. scintillans was recorded again in the whole basin, although there was no other signal of increasing eutrophication. In contrast to all previous observations, during winter 2002–2003, N. scintillans was continuously sampled in the Gulf of Trieste. We estimated experimentally growth and grazing rates of the dinoflagellate at 9–10°C in culture and consuming the natural assemblage. Noctiluca scintillans was able to reproduce actively at low temperatures, showing similar growth rates in both experiments (k = 0.2 day−1). The values found were close to those reported in the literature for higher temperatures. The natural diet was mainly composed of phytoplankton (ingestion = 0.008 μg C Noctiluca −1 day−1), microzooplankton (ingestion = 0.008 μg C Noctiluca −1 day−1) and bacteria (ingestion = 0.005 μg C Noctiluca −1 day−1) with an average carbon content of 0.138 ± 0.020 μg C Noctiluca cell−1. [ABSTRACT FROM PUBLISHER]