Bacterial and size fractionated primary production within a large Karenia brevis bloom on the West Florida Shelf

摘要: In October 2001, bacterial and size-fractionated primary productivity was measured within and outside a large Karenia brevis bloom on the west Florida shelf (WFS). Primary production in the> 0.2 µm fraction within the bloom ranged from 19.2 to 127.3 mg C m–3 hr–1, while depth integrated values ranged from 2.9 to 14.3 mg C m–2 d–1. An average of 52.3 (±18.8)% of production occurred in the> 3.0 µm fraction and could be attributed directly to K. brevis. Smaller Karenia cells (ie, gamete-like cells, recently divided or amitotically produced cells) composed up to 32.2% of total Karenia abundance within the bloom and possibly accounted for significant production in the 0.4–3.0 µm fraction. Outside the bloom, rates of primary production within oligotrophic surface water, the deep chlorophyll a maximum and Trichodesmium populations were 1.76, 5.29 and 2.64 mg C m–3 d–1, respectively. Concurrent bacterial …