Inorganic nutrient distribution at Saya de Malha and the eastern slope of the Nazareth Banks

Abstract

The distribution of nutrients in the Mascarene Plateau is poorly studied due to limited data collected in the region. This study investigated the distribution of nutrients in the water column of the Saya de Malha and eastern slope of the Nazareth Banks. Water samples were collected at the Saya de Malha and eastern slope of Nazareth Banks during the scientific expedition on board the R/V Fridtjof Nansen in May 2018 and the vertical profiles of physical parameters were used to identify the different water masses. Phosphate, nitrate and silicate showed typical nutrient profiles along with the nutriclines. The dissolved oxygen and chlorophyll-a showed a correlation with nutrients. Most of the sampling stations on the Saya de Malha and Nazareth Banks showed high oxygen saturation above 92 % in the upper 75 m. Low chlorophyll-a values were recorded at both banks indicating an oligotrophic system. The nutrient results also reveal an increase in the concentration towards the northern part of the region due to the South Equatorial Current crossing the plateau.