Woods Hole Oceanographic Institution

David Ralston

»Degree days explain an estuarine harmful algal bloom
»Sediment in the Hudson after Irene and Lee
»Waves in the Red Sea
»Lateral asymmetry and frontal trapping in sediment transport
»Fronts, stratification, and sediment on the Skagit tidal flats
»Long-term sediment transport in the Hudson
»Mixing in a salt wedge estuary
»Salt flux in the Merrimack River estuary
»Salinity and velocity in the Hudson River
»Vertical migration and bimodal distribution of phytoplankton
»Sediment transport in mudflat channels
»Shear & turbulence across subtidal channels
»Stratification & turbulence in mudflat channels
»Dispersion and lateral circulation in mudflat channels
»Scaling the estuarine boundary layer

Ralston, DK, BA Keafer, ML Brosnahan, and DM Anderson, Temperature dependence of an estuarine harmful algal bloom: Resolving interannual variability in bloom dynamics using a degree day approach, Limnology and Oceanography, 2014

Observations of harmful algal blooms (HABs) of the dinoflagellate Alexandrium fundyense in an estuary over multiple years were used to assess drivers of their spatial and temporal variability. Nauset Estuary on Cape Cod, Massachusetts has a recurrent, self-seeding A. fundyense population that produces paralytic shellfish poisoning toxins and leads to nearly annual closure to shellfishing. Weekly surveys of the entire estuary were made in 3 of 4 consecutive years, with surveys of a subembayment during the intervening year. Major A. fundyense blooms were observed all 4 years, with maximum concentrations >106 cells L-1. Concentrations were greatest in three salt ponds at the distal edges of the estuary. The bloom timing varied among the salt ponds and among years, although the blooms had similar durations and maximum cell concentrations. Nutrient concentrations did not correlate with the growth of the bloom, but differences in water temperature among years and ponds were significant. Net growth rates inferred from the surveys were similar to those from laboratory experiments, and increased linearly with temperature. A growing degree day calculation was used to account for effects of interannual variability and spatial gradients in water temperature on population development. The approach collapsed variability in the timing of bloom onset, development, and termination across years and among ponds, suggesting that this relatively simple metric could be used as an early-warning indicator for HABs in Nauset and similar areas with localized, self-seeding blooms.

FILE » RalstonEtal_LO_2014_NausetDegreeDay_198005.pdf

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