Distribution of Resting Cysts of Gonyaulax tamarensis var. excavata and Shellfish Toxicity

Abstract

Our objective was to determine whether intertidal dinoflagellate resting cyst distributions might be useful for determining areas which should be closely monitored for toxins in shellfish. Gonyaulax tamarensis var. excavata cyst distributions in Gulf of Maine sediments were examined semiquantitatively each winter for a 5-yr period and compared with locations of shellfish toxicity. Although distribution patterns over broad geographical ranges may be a reflection of shellfish toxin rise, they do not predict timing of future shellfish intoxication at specific locations.

Evaluation of iron as a triggering factor for red tide blooms

“…There are no major freshwater inputs to the study area, although the region is influenced by runoff from the Penobscot River situated 100 km to the northeast. During 1988, red tide outbreaks occurred repeatedly in the study area and the bloom intensities, inferred from the saxitoxin con-centrations in blue mussel tissues, were similar to those in earlier years (Thayer et al 1983, J. Hurst pers. comm.…”

Cysts and Sediments: Gonyaulax Polyedra (Lingulodinium Machaerophorum) in Loch Creran

“…There have been several approaches, of which two are relevant to this investigation. The studies of palynologists who endeavour to relate the distribution of cyst assemblages to environmental factors (for example Reid, 1972;Wall et al 1977;Harland, 1983) and the studies of phycologists, concerned with toxic dinoflagellate blooms, who concentrate on the distributions of cysts of bloom species (for example Anderson, Kulis et al 1982;Thayer et al 1983).…”

Shellfish Toxicity and Dormant Cysts in Toxic Dinoflagellate Blooms

“…However, the data provide no direct evidence and are only applicable to shallow estuaries at the southern limit of the tamarensis geographic distribution in New England, since it is in this region that the blooms and the cyst distributions are patchy and localized. Recent surveys in Maine where cysts are more widespread have not shown a good correlation between cyst distributions and the patterns of PSP outbreaks (16).…”

“…The link between cysts and bloom initiation becomes more tenuous in regions where the cysts are widespread in estuarine and nearshore sediments (16,19,20). For example, given the need for 5-8°C temperatures for germination (18,21), the fate of cysts deposited in 100 m or deeper coastal water remains an open question since bottom temperatures can be relatively invariant near 4°c (22).…”