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The occurrence and variability of domoic acid (DA) levels in wild Mytilus galloprovincialis samples, compared with the Pseudo-nitzschia spp. abundance and particulate DA (pDA) concentrations in relation to the environmental changes in the Golden Horn Estuary, Turkey from October 2018 to September 2019. Biotoxin analysis were performed by high-performance liquid chromatography with diode-array detection (HPLC-DAD). DA concentrations in particulate matter (pDA) and mussel samples were found between 0.090-0.685 µg L -1 and 0.905-2.413 µg g -1 , respectively. Accumulation of DA in wild mussel samples could be the result of the increasing tendency of P.nitzschia spp. abundances between April and May. Maximum DA levels were detected in particulate matter when the salinity was measured as the lowest in May. Thus, it can be said that the DA production was driven by the significant salinity decrease in the GHE. This is the first attempt regarding the presence of DA in M. galloprovincialis samples collected from Turkish coasts.

This study reports the first evidence of domoic acid (DA), an algal neurotoxin produced by the genus Pseudo-nitzschia, from plankton net samples collected in the Sea of Marmara in December, 2010 and February, 2011. DA concentrations of plankton net samples were analyzed by high-performance liquid chromatography (HPLC), using the fluorenylmethoxycarbonyl fluorescence derivatization technique (detection limit 0.2 ng DA). The biotoxin concentrations in samples from coastal waters varied between 0.96 and 5.25 µg DA/mL. We also investigated possible correlations between physicochemical parameters and DA concentration. The DA levels appear to be correlated negatively with silica and nitrite concentrations for both sampling periods. These data may be used to evaluate the probability of finding similar conditions in coastal waters of the Sea of Marmara in order to determine the potential risks to local aquaculture and fisheries.

The potentially toxic diatom genusPseudo-nitzschiaand particulate domoic acid (pDA) concentrations were investigated weekly to bi-weekly from October 2013 to September 2014 in the Golden Horn Estuary.Pseudo-nitzschiaspecies were detected in 324 of the 666 samples (∼49%). Two species,Pseudo-nitzschia callianthaandPseudo-nitzschia pungens, were identified based on the scanning electron microscopy examination. A bloom ofP. callianthaoccurred between May and June, average cell density, 1.1 × 106cells L−1in May.Pseudo-nitzschia callianthawas commoner thanP. pungensalmost throughout the study period. They occurred over a wide temperature range (7.4–26.3°C) and moderate salinity (5.9–19.9). The highest cell density occurred at 14.7–19.6°C and 18.5–19.0 salinity, in the lower and middle estuary in winter and late spring.Pseudo-nitzschiaspecies were found in very low densities in the upper estuary, which has variable salinity and low light availability due to high concentrations of suspended material. The pDA concentration in seawater was 0.03–1.0 µg L−1. The distribution pattern of pDA coincided with the presence ofPseudo-nitzschia.Pseudo-nitzschiaabundance was low in October, when pDA was highest. There was a highly positive correlation betweenPseudo-nitzschiaabundance and salinity/Secchi depth/pH (p ≤ .001), but a negative correlation with inorganic nutrients and Si:N (p < .001). pDA was positively correlated with temperature/salinity and Secchi depth, but negatively correlated with inorganic nutrients (p < .001). Low light availability and highly variable salinity may limit the growth ofPseudo-nitzschiain the upper estuary and the presence of pDA throughout the study area may be related to transport by particulate matter. [ABSTRACT FROM PUBLISHER]