Potential transfer of aquatic organisms via ballast water with a particular focus on harmful and non-indigenous species: A survey from Adriatic ports

Recommendations for representative sampling methodologies in ballast water: A case study from the land-based test

Accurate assessment of ballast water's community composition and organism concentrations is crucial for effective management. Yet, the lack of standardized global sampling methods presents challenges to achieving this objective. Inconsistencies hinder data comparison across regions and vessels, impeding efficient ballast water treatment and discharge regulation. This study conducted land-based tests to establish suitable methodologies. For organisms ≥50 μm and ≥10 μm to <50 μm, the recommended max flow rate is 50 L/min; for <10 μm organisms, 25 L/min is advised to prevent cell damage. Sampling should cover substantial discharge durations. To ensure representation, ≥50 μm organisms require ≥1m3, while ≥10 μm to <50 μm and <10 μm organisms need 20 L. The ultimate aim is standardized methods for assessing ballast water across regions and vessel types, facilitating effective management to curb invasive species and protect aquatic ecosystems.

Impacts of Atmospheric and Anthropogenic Factors on Microbiological Pollution of the Recreational Coastal Beaches Neighboring Shipping Ports

A comparative study of the two northeastern ports of the Adriatic Sea indicated that the port of Rijeka is microbiologically more loaded than the port of Pula and posing a greater threat to other ports through a potential transfer of pathogens by ballast water. Fecal indicator bacteria, Escherichia coli and intestinal enterococci, were investigated seasonally in 2014–2015 in the ports and during the bathing season monitoring in the two bays where ports are located in 2009–2020. In addition, the indicators and pathogens related to human health were determined in the ports’ seawater and sediment. The determined factors contributing to microbiological pollution were higher number of tourists and locals, potential wastewater and ballast water discharge and enclosed port configuration, with high solar radiation and low precipitation reducing the negative effects. Our research points to the necessity of including Clostridium perfringens in monitoring beach sand during the bathing seasons and a wider list of pathogens in port monitoring due to a potential transfer by shipping ballast water.

Deciphering the characterization, ecological function and assembly processes of bacterial communities in ship ballast water and sediments

Various microorganisms are transported worldwide via the water and sediments inside ship ballast tanks. Nevertheless, the ecological functions and assembly processes of bacterial communities in ballast water and sediments remain poorly understood. Here, we investigated the bacterial composition, community assembly processes, and putative functions through analyses of 70 ballast water and sediment samples obtained from various ships. The results showed that the ballast sediments contained a higher diversity of bacterial communities, whereas the ballast water was characterized by the dominance of Proteobacteria. Both the composition and potential function structures of bacterial communities were clearly different between the ballast water and sediment samples. The ballast water exhibited an abundance of microorganisms that involved in sulfur oxidation, whereas the bacterial species associated with nitrogen metabolism were abundant in the sediments. Co-occurrence network analysis revealed that the communities in ballast sediment samples possessed more complex network structures with higher modularity and positive associations among bacterial populations. Stochastic processes, especially the dispersal limitation process played the most important influence in the assembly of the communities in ballast water. Meanwhile, the bacterial communities in the ballast sediments were primarily governed by the homogeneous selection of determinacy. The results from this study will help us understand the ecological processes related to the bacterial communities in the ballast tanks and provide a foundation for the management of ballast water and sediments.

Molecular detection of E. coli and Vibrio cholerae in ballast water of commercial ships: a primary study along the Persian Gulf

PURPOSE

Ballast water is one of the most important ways for the transfer of aquatic organisms such as Escherichia coli (E. coli) and Vibrio cholerae. The aim of this study was to investigate Mdh gene of E. coli and the OmpW gene of Vibrio cholerae bacteria by PCR technique in the ballast water of commercial ships entering Bushehr port along the Persian Gulf.

METHODS

In this study, 34 samples of ballast water entered Bushehr port were studied by using culture and PCR methods to determine Mdh gene of E. coli and OmpW gene of Vibrio cholerae. Genomic DNA of bacterial strains was extracted and PCR was performed by using specific primers of E. coli and Vibrio cholerae.

RESULTS

The specific Mdh gene of E. coli was detected in 4 ballast water samples and the positive samples were analyzed by antisera methods for E. coli O157:H7. Results of antisera showed that there were 3 positive samples of O157:H7 serotype. The results of the PCR technique showed that the OmpW gene of Vibrio cholerae was negative for all positive culture samples.

CONCLUSIONS

Further studies are highly recommended to monitor other aquatic organisms in ballast water to protect the marine environment.

Sedimentary organic matter composition from tropical ports with distinct geographic and morpho-hydrodynamic characteristics: Evaluation through multiple biochemical markers

Increasing coastal urbanization and shipping activity-related environmental pollution advocate the importance of assessment of port ecosystems. Fatty acid biomarkers, elemental components, and biopolymers were used to evaluate the composition of sedimentary organic matter and benthic trophic status of Kolkata (freshwater, enclosed docks) and Kandla (seawater, macrotidal) ports of India. The sediment fatty acid composition indicated relatively fresh and energy-rich organic matter of phytoplankton and bacterial origin inside Kolkata port than the outside riverine station and Kandla port. Biopolymeric carbon (BPC), used as an indicator of trophic status, revealed eutrophic condition in Kolkata port with high accumulation of organic matter of autochthonous origin, attributed to poor water flushing and input of anthropogenic wastes. In contrast, Kandla port was meso-oligotrophic, rich in bacteria, and terrestrial plant-derived materials. Such an assessment of ports' trophic status helps to evaluate the health of the ecosystem and in management practices.

Seasonal and Interannual Trends of Oceanographic Parameters over 40 Years in the Northern Adriatic Sea in Relation to Nutrient Loadings Using the EMODnet Chemistry Data Portal

Long-term data series (1971–2015) of physical and biogeochemical parameters were analyzed in order to assess trends and variability of oceanographic conditions in the northern Adriatic Sea (NAS), a mid-latitude shallow continental shelf strongly impacted by river discharges, human activities and climate changes. Interpolation maps and statistical models were applied to investigate seasonal and spatial variability, as well as decadal trends of temperature, salinity, chlorophyll-a and nutrients. This analysis shows that sea surface temperature increased by +0.36% year−1 over four decades. Annual mean flow of the Po River markedly changed due to the occurrence of periods of persistent drought, whereas the frequency of flow rates higher than 3000 m3 s−1 decreased between 2006 and 2015. Moreover, we observed a long-term decrease in surface phosphate concentrations in Po River water (−1.34% year−1) and in seawater (in summer −2.56% year−1) coupled, however, to a significant increase in nitrate concentration in seawater (+3.80% year−1) in almost all seasons. These changes indicate that the nutrient concentrations in the NAS have been largely modulated, in the last forty years, by the evolution of environmental management practices and of the runoff. This implies that further alteration of the marine environment must be expected as a consequence of the climate changes.

Electrochemical immunosensor functionalized with nanobodies for the detection of the toxic microalgae Alexandrium minutum using glassy carbon electrode modified with gold nanoparticles

In this work an electrochemical immunosensor for the toxic microalgae Alexandrium minutum (A. minutum AL9T) detection is described. A glassy carbon electrode (GCE) was modified by depositing gold nanoparticles followed by L-cysteine for obtaining a self-assembled monolayer. The SpyTagged nanobody C1, specific for the A. minutum toxic strain AL9T, was then covalently immobilized via SpyCatcher on the surface of the modified electrode and used for the selective capture of such microalgae strain. Electrochemical impedance spectroscopy (EIS) was used for the quantification of A. minutum cells present in water samples by measuring the charge-transfer resistance changes of the electrode with a hexacyanoferrate probe. Each electrode modification step was accompanied by cyclic voltammetry (CV) and scanning electron microscopy (SEM). The immunosensor provided highly reproducible data, was simple to fabricate at low cost, exhibited higher sensitivity than previously described alternative diagnostic methods and showed a broad linear range between 10³ and 10⁹ cells L^-1 with detection limit of 3 × 10³ cells L^-1 of A. minutum AL9T. The immunosensor was successfully applied to quantify A. minutum AL9T in seawater and brackish water samples proving that it can be used for early detection of harmful microalgae without the necessity of pre-concentration or dialysis steps.

Multi-marker metabarcoding approach to study mesozooplankton at basin scale

Zooplankton plays a pivotal role in marine ecosystems and the characterisation of its biodiversity still represents a challenge for marine ecologists. In this study, mesozooplankton composition from 46 samples collected in summer along the western Adriatic Sea, was retrieved by DNA metabarcoding analysis. For the first time, the highly variable fragments of the mtDNA COI and the V9 region of 18S rRNA genes were used in a combined matrix to compile an inventory of mesozooplankton at basin scale. The number of sequences retrieved after quality filtering were 824,148 and 223,273 for COI and 18S (V9), respectively. The taxonomical assignment against reference sequences, using 95% (for COI) and 97% (for 18S) similarity thresholds, recovered 234 taxa. NMDS plots and cluster analysis divided coastal from offshore samples and the most representative species of these clusters were distributed according to the dominant surface current pattern of the Adriatic for the summer period. For selected sampling sites, mesozooplankton species were also identified under a stereo microscope providing insights on the strength and weakness of the two approaches. In addition, DNA metabarcoding was shown to be helpful for the monitoring of non-indigenous marine metazoans and spawning areas of commercial fish species. We defined pros and cons of applying this approach at basin scale and the benefits of combining the datasets from two genetic markers.