Leucine and thymidine incorporation were examined in size-fractionated estuarine communities and in cultures of phytoplankton known to use dissolved organic nitrogen (DON). Cultured phytoplankton species were used to establish that phytoplankton took up leucine and thymidine into protein and DNA, respectively. Subsequently, incorporation of leucine and thymidine was measured in size-fractionated populations collected from the Lafayette River, VA, a eutrophic estuary where resident populations contain bloom-forming phytoplankton known to take up DON, and the Gulf of Mexico during a bloom of the mixotrophic red tide dinoflagellate, Karenia brevis. We examined the efficacy of size fractionation for determining phytoplankton versus bacterial incorporation of leucine and thymidine under conditions employed during bacterial productivity bioassays, and antibiotics were used to distinguish between bacterial and phytoplankton incorporation in cultured and natural populations. Results suggest that cultures and natural assemblages of phytoplankton can take up both leucine and thymidine when supplied at low concentrations (10 and 12 nmol L¯¹, respectively) and during short incubations (15 min to 1 h). In natural populations, up to 95% of the leucine and thymidine incorporation during short bioassays was recovered in the > 5.0-µm size fraction that contained ≥4.2% of the bacterial biomass.
Estuaries & Coasts is the journal of the Coastal and Estuarine Research Federation. Begun in 1977 as Chesapeake Science, the journal has gradually expanded its scope and circulation. Today, the journal publishes manuscripts covering aspects of research on physical, chemical, geological or biological systems, as well as management of those systems, at the interface between the land and the sea. The interface is broadly defined to include areas within estuaries, lagoons, wetlands, tidal rivers, watersheds that include estuaries, and near-shore coastal waters. The journal publishes original research findings, reviews, techniques, and comments.
The Coastal and Estuarine Research Federation is a private, nonprofit non partisan organization. The Federation was created in 1971, when the members of two older, regionally-based estuarine research societies (AERS and NEERS) decided that a national organization was needed to address estuarine and coastal issues more broadly. The regionally based Affiliate Societies now number seven and encompass all of the coastal regions that border the United States, Canada and Mexico.