Chlorophyll a and nutrient distribution around seamounts and islands of the tropical south-western Atlantic

Research around the seamounts and islands of north-eastern Brazil, including UNESCO World Heritage Sites such as Fernando de Noronha, reveals that topography interacts with oceanic flows to create highly patchy distributions of chlorophyll a and inorganic nutrients. The study, conducted during large-scale surveys in 1997 and 1998, found significant variability in nutrient concentrations—ranging from undetectable levels to peaks of 17.52 µm L⁻¹ for silicon, 10.02 µm L⁻¹ for nitrate, and 3.91 µg L⁻¹ for chlorophyll a. Notably, 1998 showed more uniform nutrient distributions with lower chlorophyll a and higher phosphate concentrations compared to 1997. The findings also highlight an inverse linear relationship between nutrients (nitrite and nitrate) with temperature and salinity, alongside an exponential decay relationship with chlorophyll a, suggesting complex thermohaline interactions shaping marine productivity in these tropical regions.

Sampaio de Souza, C., Guimarães da Luz, J. A., Macedo, S., Montes, M. d. J. F., & Mafalda, P. (2013). Chlorophyll a and nutrient distribution around seamounts and islands of the tropical south-western Atlantic. Marine and Freshwater Research, 64(2), 168–184. https://doi.org/10.1071/mf12075