Parmales ecology in Magdalena Bay, Mexican Pacific coast

Cell densities of Parmales (a group of siliceous marine phytoplankton) were determined in 81 water samples from depths of 0–60 m on a monthly basis from October 2009 and October 2010 in Magdalena Bay, Mexican Pacific coast. The highest cell densities of Parmales were recorded in sub-surface waters between 0 and 15 m water depth and reached maximum cell densities of up to 40 × 10³ cells L⁻¹ in July at 10 m depth. In total five Parmales species were identified: Triparma columacea f. columacea, T. retinervis f. retinervis, T. laevis f. mexicana, T. strigata and Tetraparma insecta. The present study suggests that cell densities of Parmales are associated with increased nutrient levels during the upwelling period from April to July.