Climate change is predicted to increase the frequency and severity of extreme events. However, the biological consequences of extremes remain poorly resolved owing to their unpredictable nature and difficulty in quantifying their mechanisms and impacts. One key feature delivering precipitation extremes is an atmospheric river (AR), a long and narrow filament of enhanced water vapour transport. Despite recent attention, the biological impacts of ARs remain undocumented. Here, we use biological data coupled with remotely sensed and in situ environmental data to describe the role of ARs in the near 100% mass mortality of wild oysters in northern San Francisco Bay. In March 2011, a series of ARs made landfall within California, contributing an estimated 69.3% of the precipitation within the watershed and driving an extreme freshwater discharge into San Francisco Bay. This discharge caused sustained low salinities (less than 6.3) that almost perfectly matched the known oyster critical salinity tolerance and was coincident with a mass mortality of one of the most abundant populations throughout this species' range. This is a concern, because wild oysters remain a fraction of their historical abundance and have yet to recover. This study highlights a novel mechanism by which precipitation extremes may affect natural systems and the persistence of sensitive species in the face of environmental change.
Cheng et al PRSB Oyster Density Dataset 1
Oyster density data from Village North, Rat Rock, and Weber Point. Columns are variables and rows are replicate data points. Date = date of survey in month/day/year format. Site = one of the above described sites. Recorders = initials of surveyors. Mini-quadrat = quadrat number within the larger quadrat. Height = tidal height where Low = 0.0 m, Mid = 0.05 m, High = 0.10 m above mean lower low water. Distance = position of the quadrat in meters along the transect. Alive = number of live Olympia oysters. Ostrea.25m = number of live oysters per 0.25 meters squared. Notes = notes for each replicate.
Cheng et al PRSB Oyster Density Dataset 2
Oyster density data from Bullhead Flat. Site = Bullhead Flat (all data from this file is from this site). Date = date of survey in month/day/year format. Year = year in full year format. Quadrat = quadrat number. OstreaLive = number of live oysters within the quadrat. OstreaDead = number of dead oysters within the quadrat.
Cheng et al PRSB Oyster Size Frequency Data
Oyster size frequency data from field quadrat surveys at Bullhead Flat. Date = date in month/day/year format. Site = Bullhead Flat for all rows. Recorders = initials of surveyors. Quadrat = quadrat number. Oyster.Length = oyster length in mm.
Cheng et al PRSB Oyster Recruitment Data
Oyster recruitment data from Bullhead Flat. Ceramic tiles were deployed on racks in the intertidal zone. Timeframe = frequency of sampling (Quarterly or Monthly). Date.In = date of tile outplant in month/day/year format. Date.Out = date of tile recovery in month/day/year format. Approximate.season = season that tile was deployed during. Year = year in full year format. Site = site that tiles were deployed at (China Camp = Bullhead Flat). Site Code = code for site (all values = CC). Frame = the frame number that the tile was attached to. Tile = letter for each tile per frame. oyster.count = number of oyster recruits per tile. count.m2 = number of oysters recruits extrapolated to a meter squared. days.in.field = the number of days that a tile was deployed for. count.m2.day = count.m2 column divided by the days.in.field column.
