Domoic acid in phytoplankton net samples and shellfish from the Krka River estuary in the Central Adriatic Sea

This paper deals with the precise identification of species of Pseudo-nitzschia, focusing on those which are a potential source of domoic acid, from the Krka River estuary of the Central Adriatic Sea. Domoic acid was measured in phytoplankton net samples and shellfish collected in the winter and early spring of 2011 and 2012. Domoic acid was only detected in early March 2011, both in plankton net samples and shellfish extracts, during a Pseudo-nitzschia species bloom. The measured concentrations of particulate domoic acid (DA) in filtered concentrated seawater varied from 3.1˗6.2 ng DA ml-1. In shellfish sample DA concentration was 0.2 μg g-1. Species belonging to the Pseudo-nitzschia delicatissima complex were more common than those from the Pseudo-nitzschia seriata complex. Morphological analyses by electron microscopy revealed the presence of three potentially toxic species: P. calliantha, P. pseudodelicatissima and P. pungens, and one non-toxic species: P. subfraudulenta. However, P. calliantha and P. pseudodelicatissima dominated during the March 2011 bloom. This study presents the first evaluation of particulate domoic acid along the Eastern Adriatic Sea and the first record of the presence of P. calliantha, P. pseudodelicatissima, P. pungens and P. subfraudulenta in the Krka River estuary

The impacts of seawater physicochemical parameters and sediment metal contents on trace metal concentrations in musselsa chemometric approach

The concentrations of Al, Ba, Cd, Co, Cr, Cu, Fe, Li, Mn, Ni, Pb, Sr, Zn, and Hg were studied in Mytilus galloprovincialis collected from the coastal area of Montenegro. The impact of seawater temperature, salinity, dissolved oxygen, total organic carbon (TOC), and metal content in sediment samples on the metal contents in mussels collected from three locations in four different seasons was analyzed by a Pearson correlation coefficient (r), principal component analysis (PCA), and cluster analysis (CA). These analyses were used to discriminate groups of samples, elements, and seawater parameters, according to similarity of samples chemical composition in different seasons, as well as the impact of seawater parameters and surface sediment composition on the mussels' element concentrations. Synergistic interactions occurred between seawater TOC, Fe, and Al concentrations in mussels. Compared with other studies, which are usually performed under constant laboratory conditions where mussels undergo only one stress at a time, this study was performed in nature. The analyses showed the importance of considering simultaneously acting environmental parameters that make determining of separate impacts of each factor selected very difficult and complex