Spatial and Temporal Variations of Dissolved Inorganic Nutrients and Relationship with Phytoplankton Density in Coastal Water of Kudat, Sabah, Malaysia

Coastal areas of Kudat are dominated by fisheries activities. Development of infrastructure for fishing facilities like jetty, landing centre and other human activities can increase the loading of nutrients in coastal area. High load of nutrients accelerates the blooming of phytoplankton and in long run creates eutrophication. This study was conducted to determine the temporal and spatial variations of nutrients and relationship of phytoplankton density in coastal water of Kudat. Five stations were selected with three replicated in the study area. Phytoplankton samples, water samples and in situ environmental parameters were collected from May 2019 to February 2020 (10 months). The highest concentration of nitrate (NO3) was observed in May 2019, but the highest concentration of phosphate (PO4) observed in July 2019. On the other hand, higher concentrations of phosphate (PO4) were determined than the concentration of nitrate (NO3) in all stations during study period. The distribution of nutrients is due to monsoonal runoff from surrounding areas as well due to anthropogenic activities. Among the 21 species three of them are from harmful algal species and but dominated by diatoms. Poor relationship observed among the dissolved inorganic nutrients and phytoplankton density, indicates that the relationship does not depend on only nutrients but with favourable environmental parameters. Anthropogenic activity can lead to excessive load of nutrients in Kudat coastal water and in long run cause eutrophication problem in ecosystem with potentially larger economic impacts in a long run period.

Variations in the Physicochemical Water Parameters and Phytoplankton Community in Coastal Water of Kudat, Sabah, Malaysia

This study was conducted to observe the abundance and distribution of phy-toplankton and temporal and spatial variation physico-chemical water parameters in coastal water of Kudat, Sabah, Malaysia. Water samples and in-situ water quality parameters were taken from five selected locations from May 2019 to February 2020. The sampling location was selected based on human-induced activities such as Marina Resort’s Jetty (ST1), Sabah Ports’ Jetty (ST2), aquaculture cage/pent (ST3), river’s mouth (ST4) and Landung Ayang’s water village (ST5). Water parameters: pH, salinity (ppt), dissolved oxygen (mg/L) temperature (°C) and depth (m) were recorded once every month from the selected station. Identification of phytoplanktonic species and cell density (cell/mL) were determined from collected water samples. Significant differences (p < 0.05) between physicochemical parameters to months were observed during the study period. However, in spatial variations, significant differences (p < 0.05) of pH, dissolved oxygen (mg/L) and temperature (°C) observed. A total of 21 phytoplankton species were identified from the study area, where 4 species belonged to Dinophyceae (HABs blooming species) and 17 species belonged to Bacillariophyceae. The influences of physicochemical water parameters were not significant in phytoplankton diversity and abundance. In addition to these parameters, the nutrients in the water might have important roles in the blooming of phytoplankton, which are essential and vital to address in this type of research.