Federica Grilli

Variability of nutrient and thermal structure in surface waters between New Zealand and Antarctica, October 2004-January 2005

We describe the upper ocean thermal structure and surface nutrient concentrations between New Zealand and Antarctica along five transects that cross the Subantarctic Front, the Polar Front (PF) and the southern Antarctic Circumpolar Current (ACC) front. The surface water thermal structure is coupled with variations in surface nutrient concentrations, making water masses identifiable by both temperature and nutrient ranges. In particular, a strong latitudinal gradient in orthosilicate concentration is centred at the PF. On the earlier sections that extend south-west from the Campbell Plateau, orthosilicate increases sharply southward from 10–15 to 50–55 µmol l−1 between 58° S and 60° S, while surface temperature drops from 7°C to 2°C. Nitrate increases more regularly toward the south, with concentrations ranging from 10–12 µmol l−1 at 54° S to 25–30 µmol l−1 at 66° S. The same features are observed during the later transects between New Zealand and the Ross Sea, but the sharp silica and surface temperature gradients are shifted between 60° S and 64° S. Both temporal and spatial factors may influence the observed variability. The January transect suggests an uptake of silica, orthophosphate and nitrate between 63° S and 70° S over the intervening month, with an average depletion near 37%, 44% and 29%, respectively. An N/P (nitrite + nitrate/orthophosphate) apparent drawdown ratio of 8.8±4.1 and an Si/N (silicic acid/nitrite + nitrate) apparent drawdown ratio >1 suggest this depletion results from a seasonal diatom bloom. A southward movement of the oceanic fronts between New Zealand and the Ross Sea relative to prior measurements is consistent with reports of recent warming and changes in the ACC.

Phytoplankton diversity in Adriatic ports: Lessons from the port baseline survey for the management of harmful algal species

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.

Status of faecal pollution in ports: A basin-wide investigation in the Adriatic Sea

Ports are subject to a variety of anthropogenic impacts, and there is mounting evidence of faecal contamination through several routes. Yet, little is known about pollution in ports by faecal indicator bacteria (FIB). FIB spatio-temporal dynamics were assessed in 12 ports of the Adriatic Sea, a semi-enclosed basin under strong anthropogenic pressure, and their relationships with environmental variables were explored to gain insight into pollution sources. FIB were abundant in ports, often more so than in adjacent areas; their abundance patterns were related to salinity, oxygen, and nutrient levels. In addition, a molecular method, quantitative (q)PCR, was used to quantify FIB. qPCR enabled faster FIB determination and water quality monitoring that culture-based methods. These data provide robust baseline evidence of faecal contamination in ports and can be used to improve the management of routine port activities (dredging and ballast water exchange), having potential to spread pathogens in the sea.

Strategy of port baseline surveys (PBS) in the Adriatic Sea

Port baseline surveys (PBS) provide species inventories in and around ports, with a focus on non-indigenous species that may have been introduced by vessels, primarily via ballast water. PBS are an essential tool to support effective management strategies for non-indigenous as well as native harmful aquatic organisms and pathogens (HAOP). This paper describes the methodology of PBS that were conducted in 12 Adriatic ports. The PBS employed existing protocols that were adapted to meet the characteristics of the Adriatic sites. Their results are reported in several papers included in this special issue, each of which is devoted to a specific community. An overview of existing surveys protocols - which provide valuable support to decision-making and to design effective monitoring of non-indigenous species - is also supplied.