Phytoplankton community changes in Kuantan Port (Malaysia), with emphasis on the paralytic-shellfish toxin-producing dinoflagellate Alexandrium tamiyavanichii

The Kuantan Port (Pahang, Malaysia, South China Sea) is a multi-cargo port located on the east coast of Peninsular Malaysia. The port has served as an important seaway to major ports in Asia-Pacific regions. In November 2013 and August 2014, two incidents of paralytic shellfish poisoning (PSP) have been consecutively reported in the Port. In this study, a field investigation was undertaken in the Port from April 2015 to May 2016 as an effort to continuously monitor the occurrence of HAB species following the PSP episodes in the year 2013–2014. Phytoplankton and hydrographic samples were collected for quantitative and qualitative assessments in a monthly interval. To precisely quantify the PSP-toxins producing species Alexandrium tamiyavanichii, a real-time quantitative PCR (qPCR) assay was applied to detect the motile cells and cysts. The results revealed the presence of A. tamiyavanichii but with extremely low cell abundances (<0.1% of the total abundances). The species was found co-existed with other Alexandrium species. Alexandrium abundance was associated with salinity and nitrogen to phosphorus ratios but negatively correlated with PO4-P and NH4-N as revealed in the canonical correspondence analysis. Low cell abundances of diarrhetic-shellfish toxins producing dinoflagellates (Dinophysis spp.) and fish-killing species (Prorocentrum sigmoides, Akashiwo sanguinea, Noctiluca scintillans, Chattonella spp.) were also encountered in the port. The results of this study would provide useful baseline information for the assessment and management of ballast water in Malaysian ports and its territorial waters

First report of paralytic shellfish poisoning (PSP) caused by Alexandrium tamiyavanichii in Kuantan Port, Pahang, East Coast of Malaysia

Harmful algal bloom (HAB) is a proliferation of algae, which naturally produce biotoxins and cause harmful effects to humans, the environment and organisms associated with it. Paralytic shellfish poisoning (PSP) was reported for the first time in Kuantan Port, Pahang, Malaysia, in November 2013, followed by a second episode in August 2014. The toxicity level reported during the second event was as high as 3500 μg of STX equiv./100 g shellfish. Ten people were hospitalized with PSP symptoms after consuming contaminated shellfish. This study was conducted at Kuantan Port to identify the organisms responsible for these events. Water samples were collected monthly for a period of 12 months beginning in September 2014. HAB species were identified based on their morphology using light and fluorescence microscopes, and their classification was supported by molecular evidence based on internal transcribed spacer (ITS) sequences. Monthly cell abundance of Alexandrium tamiyavanichii was measured at four sampling stations. Toxin production by three strains isolated from the area was determined using HPLC. Our results revealed the presence of several HAB species, including the PSP-producing species A. tamiyavanichii. The highest cell density of A. tamiyavanichii was 840 cells L−1 . The presence of GTX components was detected in these strains. However, other toxin components could not be determined.This study reported, for the first time, the presence of PSP-producing A. tamiyavanichii on the Pahang coast of east Peninsular Malaysia and confirmed that the PSP events in Kuantan Port were attributable to this species. The presence of this species further indicates that several safety measures need to be considered to safeguard public health, particularly in Pahang coastal water