Meteorological influences on algal bloom potential in a nutrient‐rich blackwater river

Summary 1. The effect of variability in rainfall on the potential for algal blooms was examined for the St Johns River in northeast Florida. Water chemistry and phytoplankton data were collected at selected sites monthly from 1993 through 2003. Information on rainfall and estimates of water turnover rates were used in the analyses of trends in phytoplankton biomass. 2. Major trends in rainfall and runoff within the lower St Johns River catchment over the 10-year study period were marked by both significant drought and flood periods. Autumn and winter rainfall patterns were strongly correlated with the range of Pacific sea surface temperature anomalies associated with El Nino events and La Nina periods. The effect of these major shifts in rainfall was evident in the strong relationship to replacement rates for water within the lower St Johns River. 3. The eutrophic status of the river was reflected in the high concentrations of nitrogen and phosphorus observed at all sampling sites, with total nitrogen concentrations up to 3100 μg L−1 and total phosphorus concentrations up to 180 μg L−1. 4. While it is clear that the high phytoplankton biomass and frequent blooms that characterize the freshwater portions of the lower St Johns River are fundamentally based on nutrient status, the expression of that potential was strongly correlated to water replacement rates, as revealed by the inverse relationship between phytoplankton biovolume increase and water turnover rate, with an R2 of 0.80 for the major bloom season. The sensitivity of algal blooms to rainfall patterns over the 10-year study period suggest that longer-term temporal and spatial shifts in rainfall, such as multi-decadal cycles and the global-warming phenomenon, will also influence the frequency and intensity of algal blooms.

[1]  Jef Huisman,et al.  Population Dynamics of Harmful Cyanobacteria , 2005 .

[2]  E. Phlips,et al.  The relationships among phytoplankton biomass, nutrient loading and hydrodynamics in an inner-shelf estuary , 2004 .

[3]  P. Raimbault,et al.  Does competition for nanomolar phosphate supply explain the predominance of the cyanobacterium Synechococcus? , 2002 .

[4]  Y. Monbet,et al.  Control of phytoplankton biomass in estuaries: A comparative analysis of microtidal and macrotidal estuaries , 1992 .

[5]  T. Krogstad,et al.  Erosion, phosphorus and phytoplankton response in rivers of South-Eastern Norway , 1989, Hydrobiologia.

[6]  M. Pace,et al.  Zooplankton in Advective Environments: The Hudson River Community and a Comparative Analysis , 1992 .

[7]  H. Paerl,et al.  Zooplankton community structure, micro-zooplankton grazing impact, and seston energy content in the St. Johns river system, Florida as influenced by the toxic cyanobacterium Cylindrospermopsisraciborskii , 2005, Hydrobiologia.

[8]  M. Présing,et al.  Growth and phosphate uptake kinetics of the cyanobacterium, Cylindrospermopsis raciborskii (Cyanophyceae) in throughflow cultures , 2000 .

[9]  B. L. Kimmel,et al.  A Large-Scale Comparison of Factors Influencing Phytoplankton Abundance in Rivers, Lakes, and Impoundments. , 1987, Ecology.

[10]  K. Havens,et al.  Light availability as a possible regulator of cyanobacteria species composition in a shallow subtropical lake , 1998 .

[11]  Thomas L. Crisman,et al.  Relationships between light availability, chlorophyll a, and tripton in a large, shallow subtropical lake , 1995 .

[12]  D. Schindler,et al.  The effects of climatic warming on the properties of boreal lakes and streams at the Experimental Lakes Area, northwestern Ontario , 1996 .

[13]  R. Livingston.  The Rivers of Florida , 1991, Ecological Studies.

[14]  E. Phlips,et al.  Light availability and variations in phytoplankton standing crops in a nutrient‐rich blackwater river , 2000 .

[15]  Ercan Kahya,et al.  The relationships between U.S. streamflow and La Niña Events , 1994 .

[16]  Thomas C. Piechota,et al.  Drought and Regional Hydrologic Variation in the United States: Associations with the El Niño-Southern Oscillation , 1996 .

[17]  F. Pick,et al.  Factors regulating phytoplankton and zooplankton biomass in temperate rivers , 1996 .

[18]  W. Lewis.  Primary Production in the Orinoco River , 1988 .

[19]  Dieter Gerten,et al.  Climate‐driven changes in spring plankton dynamics and the sensitivity of shallow polymictic lakes to the North Atlantic Oscillation , 2000 .

[20]  E. Phlips,et al.  A Comparison of Water Quality and Hydrodynamic Characteristics of the Guana Tolomato Matanzas National Estuarine Research Reserve and the Indian River Lagoon of Florida** , 2004 .

[21]  F. Pick,et al.  Temporal variability of water chemistry in flowing waters of the northeastern United States: does river size matter? , 2001, Journal of the North American Benthological Society.

[22]  B. Kjerfve,et al.  Trophic state and water turn-over time in six choked coastal lagoons in Brazil , 1991 .

[23]  F. Pick,et al.  Longitudinal and seasonal development of planktonio chlorophyll a in the Rideau River, Ontario , 1995 .

[24]  William J. Oswald,et al.  Photosynthesis in Sewage Treatment , 1957 .

[25]  Ercan Kahya,et al.  U.S. streamflow patterns in relation to the El Niño/Southern Oscillation , 1993 .

[26]  Dietmar Straile,et al.  The North Atlantic Oscillation and plankton dynamics in two European lakes –‐ two variations on a general theme , 2000 .

[27]  E. Phlips,et al.  Relationships between phytoplankton standing crop and physical, chemical, and biological gradients in the Suwannee River and plume region, U.S.A. , 2000 .

[28]  G. Minshall,et al.  The River Continuum Concept , 1980 .

[29]  B. Moss,et al.  Phytoplankton distribution in a temperate floodplain lake and river system. I. Hydrology, nutrient sources and phytoplankton biomass , 1989 .

[30]  F. Jones.  The dynamics of suspended algal populations in the lower Wye catchment , 1984 .