General Information

Event name: US-16-026
Nature of the harmful event:
Water Discoloration , High Phyto concentration
Event directly affected:
Natural Fish , Shellfish
Toxicity detected: No
Associated syndrome:
Unexplained toxicity:
Species implicated in toxin transmission (transvector):
Report the outcome of a monitoring programme: Yes (VIMS HAB Monitoring Program)
Event occurred before in this location: Yes
Individuals to contact: REECE, kimberly

Location & Date

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Location: Latitude: , Longitude:
General location information: Mobjack Bay and York River, Chesapeake Bay
HAB Area code(s): US-10
Additional location information: Mobjack Bay into the Chesapeake Bay into the York River extending to the Naval Weapon Station. First seen at bloom levels (>1,000,000 cells/L) on August 17, 2016; last seen at bloom levels in this region on September 23, 2016
Bloom event dates (yyyy/mm/dd): Start: 2016-08-17, End: 2016-09-23
Quarantine levels dates (yyyy/mm/dd):
Additional date-related information:


Causative organism known: Yes
Causative Species/Genus: Alexandrium monilatum (119,772,000 cells/L)
Co-Ocurring Species/Genus: Cochlodinium polykrikoides (500,000 cells/L)
Chlorophyll concentration, if known: up to 616 ug/l on August 23, 2016 µg/l
Additional bloom information: C. polykrikoides was co-occurring at the start of the bloom. There was no other co-occuring dominant species until the bloom started subsiding at which point Pheopolykrikos hartmannii was present at concentrations up to 98,000 cells/L
Event-related bibliography:

Environmental Conditions

Weather: Turbidity (NTU): Wind direction:
Stratified water: Oxygen content (nL/L): 15.13 Wind velocity:
Temperature (°C): 29 Oxygen saturation %: Current Direction:
Sechhi disk (m): Salinity: 23.3 Current Velocity:
Nutrient information:
Temperature Range During Event: Max: 34 °C, Min: 25 °C
Salinity Range During Event: Max: 24, Min: 20
Bloom location in the water column:
In situ
Growth Comments
Additional Environmental information: pH 8.4; extracted CHLa 616.3 for 8/23/16 sample listed above

Toxin Assay Information

Species containing the toxin Toxin type Toxin details Max. concentration Assay type
Kit used: No Type of kit used:
Additional information:
Economic losses: Oyster spat loss of entire stock for one grower. Another grower experienced ~67% mortality in a group of diploid oysters grown intertidally, while those in the same group grown subtidally suffered ~22% mortality.
Management decision:
Additional harmful effect information:
Created at 06:06 on 23 Mar 2017