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An inventory of phytoplankton diversity in 12 Adriatic ports was performed with the port baseline survey. Particular emphasis was put on the detection of harmful aquatic organisms and pathogens (HAOP) because of their negative impact on ecosystem, human health, and the economy. Phytoplanktonic HAOP are identified as species, either native or non-indigenous (NIS), which can trigger harmful algal blooms (HAB). A list of 691 taxa was prepared, and among them 52 were classified as HAB and five as NIS. Records of toxigenic NIS (Pseudo-nitzschia multistriata, Ostreopsis species including O. cf. ovata) indicate that the intrusion of non-native invasive phytoplankton species has already occurred in some Adriatic ports. The seasonal occurrence and abundance of HAOP offers a solid baseline for a monitoring design in ports in order to prevent ballast water uptake and possible expansion of HAOP outside their native region., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

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., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

We studied the influence of anomalous meteorological and hydrological conditions that occurred in the Gulf of Trieste from March 2006 to February 2007 on phytoplankton structure and function. We computed monthly mean (or median) air temperature, total precipitation, wind speed, river discharge, seawater temperature, salinity, photosynthetic available radiation (PAR), cyanobacteria, nano- and microphytoplankton abundances during the study year and compared them to climatological (1999-2014 for PAR; 1999-2007 for nanophytoplankton; 1998-2015 for the other variables) mean/median data. We then related the cyanobacteria (0.2-2 μm), nano- (2-20 μm) and microphytoplankton (20-200 μm) of the study year to inorganic nutrient concentrations. Median river inputs in October and November were 9- and 15-fold lower, respectively, than the time series medians, with consequent high salinity from May to November (up to +1.26 compared to the climatological data). Monthly mean seawater temperatures were lower than the climatological values (-2.95 °C at the surface) from March to August 2006 and higher (+2.15 °C at the surface) from September to February 2007. Reductions in freshwater input and nutrient depletion were likely responsible for a decrease in microphytoplankton (median annual abundance over 60% lower than the climatologic median) and cyanobacteria (up to 47% lower than the climatology). Significant seasonal differences in cyanobacteria and microphytoplankton abundances (R ANOSIM  = 0.52; p < 0.05), as well as in seawater temperature and salinity (R ANOSIM  = 0.73; p < 0.05) between the study period and the climatology were highlighted. The late spring diatom bloom was not reflected in high photosynthetic rates whereas an unusually high primary production was estimated in November (7.11 ± 1.01 μgC L -1  h -1 ), when a mucilage event occurred due to very stable atmospheric and oceanographic conditions. The typical seasonal succession of pelagic phototrophs (micro-, nanophytoplankton and cyanobacteria) was altered since an exceptional cyanobacteria bloom first developed in April, followed by a delayed diatom bloom in May., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The response of phytoplankton assemblages to the closure of urban sewage outfalls (USOs) was examined for the Mar Piccolo of Taranto (Mediterranean Sea), a productive semi-enclosed coastal marine ecosystem devoted to shellfish farming. Phytoplankton dynamics were investigated in relation to environmental variables, with a particular emphasis on harmful algal blooms (HABs). Recent analyses evidenced a general reduction of the inorganic nutrient loads, except for nitrates and silicates. Also phytoplankton biomass (chlorophyll a) and abundances were characterized by a decrease of the values, except for the inner area of the basin (second inlet). The phytoplankton composition changed, with nano-sized species, indicators of oligotrophic conditions, becoming dominant over micro-sized species. If the closure of the USOs affected phytoplankton dynamics, however, it did not preserve the Mar Piccolo from HABs and anoxia crises. About 25 harmful species have been detected throughout the years, such as the potentially domoic acid producers Pseudo-nitzschia cf. galaxiae and P seudo-nitzschia cf. multistriata, identified for the first time in these waters. The presence of HABs represents a threat for human health and aquaculture. Urgent initiatives are needed to improve the communication with authorities responsible for environmental protection, economic development, and public health for a sustainable mussel culture in the Mar Piccolo.

Abstract: The spatial and temporal variability of phytoplankton were investigated in the southern Adriatic Sea in the period November 2006–June 2008. Three stations were sampled along the Bari–Dubrovnik transect with a seasonal frequency (except summer 2007 and spring 2008) at four depths (surface, maximum fluorescence depth and two intermediate depths), with the aim of analyzing the structure of phytoplankton community and evaluate the standing stocks of the three size fractions (pico-, nano- and microphytoplankton). Abundances were on average 5.41×107±5.97×106 cellsl−1 for picophytoplankton, 1.00×106±6.70×104 cellsl−1 for nanophytoplankton and 2.16×104±7.46×103 cellsl−1 for microphytoplankton. Total biomass ranged from 8.5 to 80.7μgCl−1. The highest values were recorded in April 2007 (38.4±5.9μgCl−1), and the lowest ones in February 2008 (13.8±1.5μgCl−1). Picophytoplankton was generally the most abundant phototrophic fraction (on average, 96% of the total abundances and 49% of the total biomass), while nano- and microphytoplankton provided a minor contribution (4% and less than 1% of total abundance and 35% and 16% of total biomass for nanophytoplankton and microphytoplankton, respectively). A decreasing gradient from west to east was observed for pico- and nanophytoplankton abundances and for total biomass. The low biomass values and the dominance of the autotrophic picoplankton fraction in the whole area reflected a general oligotrophic condition. The easternmost station (AM9), characterized by the lowest phytoplankton abundances and biomass and low nutrient concentrations, resulted in still more oligotrophic condition and probably influenced by the Ionian Surface Water (ISW), coming from the eastern Mediterranean. [Copyright &y& Elsevier]