General Information

Event name: US-20-011
Nature of the harmful event:
Water Discoloration , High Phyto concentration , Seafood toxins
Event directly affected:
Toxicity detected: No
Associated syndrome: OTHER
Unexplained toxicity: No
Species implicated in toxin transmission (transvector):
Report the outcome of a monitoring programme: Yes (Rhode Island Dept. of Environmental Management HAB monitoring)
Event occurred before in this location:
Individuals to contact: BORKMAN, David

Location & Date

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Location: Latitude: , Longitude:
General location information: Narragansett Bay and coastal salt ponds, Rhode Island
HAB Area code(s): US-07
Additional location information: Upper Narragansett Bay, Mt. Hope Bay, Lower East Passage of Narragansett Bay, Lower West Passage of Narragansett Bay, Greenwich Bay, Breton Reef, Quonochontaug Pond, Ninigret Pond
Bloom event dates (yyyy/mm/dd): Start: 2020-08-10, End: 2020-09-09
Quarantine levels dates (yyyy/mm/dd):
Additional date-related information:


Causative organism known: Yes
Causative Species/Genus: Margalefidinium polykrikoides (Margalef, 1961) F.Gómez, Richlen & D.M.Anderson, 2017 (5,000,000 cells/L)
(9/3/2020 near Conimicut Point, Upper Narragansett Bay)
Co-Ocurring Species/Genus:
Chlorophyll concentration, if known: µg/l
Additional bloom information: Dense water discoloring patches of Margalefidinium at multiple locations in Narragansett Bay RI and coastal RI salt ponds from early August to early September 2020
Event-related bibliography:

Environmental Conditions

Weather: Turbidity (NTU): Wind direction:
Stratified water: Oxygen content (nL/L): Wind velocity:
Temperature (°C): Oxygen saturation %: Current Direction:
Sechhi disk (m): Salinity: Current Velocity:
Nutrient information:
Temperature Range During Event: Max: °C, Min: °C
Salinity Range During Event:
Bloom location in the water column:
In situ
Growth Comments
Additional Environmental information:

Toxin Assay Information

Species containing the toxin Toxin type Toxin details Max. concentration Assay type
Kit used: Type of kit used:
Additional information:
Economic losses:
Management decision: Numerous phone calls and emails from the general public; provided 'rust tide' fact sheet; no shellfish or beach closures
Additional harmful effect information:
Created at 11:36 on 19 Apr 2021