Recruitment of Planktonic Dinoflagellates: Importance of Benthic Resting Stages and Resuspension Events

Abstract

Many factors have k e n put forward to account for the development of nuisance phytoplankton blooms in coastal zones. Usually hydrological factors as temperature or salinity stratification and adequate nutrient and trace metal availability are held responsible for the phenomenon. The most frequent causative organisms for nuisance blooms are dinoflagellates, many of which have a dormant stage (resting cyst) in their life cycle. The role of the complex life-strategies of these forms in initiating bloom formation is thelfocus of this study. Special attention is given to 25 different dinoflagellate resting cyst types isolated from recent German North Sea and Baltic Sea sediments, and their germination frequency under different environmental conditions. Also, the role of cyst resuspension in relationship to the timing, persistence and recurrence of dinoflagellate blooms is extensive discussed.

Spatial distribution of benthic cysts of Alexandrium catenella in surface sediments of Puget Sound, Washington, USA

“…Environmental conditions can affect both excystment , and encystment (Anderson et al, 1984;Blanco, 1995a;Figueroa et al, 2005), thereby impacting cyst abundance in the sediment. Once in the sediment, the original cyst distribution can be altered by resuspension and transport of cysts horizontally by physical processes, such as strong bottom currents (Nehring, 1996;Kirn et al, 2005), and vertically by bioturbation (Keafer et al, 1992). This study is the first to focus on the observed distribution of Alexandrium cysts in the surface sediments of Puget Sound and Samples were collected with a Soutar box corer except * collected with a van Veen grab.…”

Effects of cyst resuspension on germination and seeding of two bloom-forming dinoflagellates in the Baltic Sea

“…Here, stratification may provide optimal growth conditions and favour the formation of 'under-ice' blooms of the 2 species which have been repeatedly observed in the Baltic Sea (Niemi & Åström 1987, Larsen et al 1995. Likewise, resuspension prior to ice formation would support bloom formation under the ice, since a large inoculum is believed to enhance dinoflagellate bloom formation when conditions are favourable (Nehring 1996.…”

“…Increased turbulent mixing caused by wind, tides, or upwelling often leads to enhanced cyst resuspension (Balch et al 1983, Villanoy et al 1996, Kremp & Heiskanen 1999. Nehring (1996) hypothesized that planktonic cysts could seed a new vegetative population more efficiently than benthic cyst populations because the conditions for germination and survival of the germling, such as temperature, light or nutrient availability, may be more favourable in the pelagic environment than down in the sediment. The role of cyst resuspension as a prerequisite for seeding has also been emphasized in models of dinoflagellate population dynamics (Villanoy et al 1996, Eilertsen & Wyatt 1998.…”

Suspended Alexandrium spp. hypnozygote cysts in the Gulf of Maine

“…hours (Anderson and Wall 1978), within 12-36 hours for a variety of dinoflagellate species (Nehring 1996), and within 2-3 days in dinoflagellate cultures from Norway @ale 1977)). Although this stage is the link between dormancy and A. fundyense vegetative cell populations, no research is published on factors affecting planomeiocyte success.…”