Upstate Freshwater Institute Markensten et al. NYWEA 2008 Simulating multiple functional groups of phytoplankton in Cannonsville Reservoir Hampus Markensten 1, Don Pierson 2, Emmet M. Owens 1, Susan M. O'Donnell 1 and Steven W. Effler ) Upstate Freshwater Institute Syracuse, USA 2) Department of Environmental Protection (DEP) NYC, USA Upstate Freshwater Institute Markensten et al. NYWEA 2008 Cannonsville reservoir Second largest reservoir serving New York City with drinking water. Mesotrophic with a retention time of 2.6 years and a storage capacity of 373*10 6 m 3 of water (98.5 billion gallons). Upstate Freshwater Institute Markensten et al. NYWEA 2008 In the past Cannonsville experienced high average chlorophyll concentrations and frequent phytoplankton blooms. Cyanobacteria often dominate in summer and autumn e.g. Aphanizomenon, Anabaena and Microcystis. A one dimensional (1D) lake model that simulates temperature, hydrodynamics, nutrient dynamics and total phytoplankton biomass has previously been developed by the Upstate Freshwater Institute (UFI) (Doerr et al, 1998) and applied to the reservoir. Background DOERR, S.M., E.M. OWENS, R.K. GELDA, M.T. AUER & S.W. EFFLER Development and testing of a nutrient-phytoplankton model for Cannonsville Reservoir. Lake and Reservoir Management 14.: Upstate Freshwater Institute Markensten et al. NYWEA 2008 Overview of UFI 1D reservoir water quality model Upstate Freshwater Institute Markensten et al. NYWEA 2008 A need to predict the occurrence of bloom forming phytoplankton. Solution: Merge the existing 1D reservoir water quality model, which includes a good description of hydrodynamic and chemistry, with a model focused on the dynamics of phytoplankton groups. Compare the model performance before and after merging the two models. Objectives Upstate Freshwater Institute Markensten et al. NYWEA 2008 PROTECH (phytoplankton response to environmental change) is a model developed by Colin Reynolds in UK that focuses on the phytoplankton biology. Phytoplankton can respond to changes in nutrient, light and temperature by vertical movements to reach the most favorable depth. Phytoplankton growth rates are calculated from size and volume relationships that affect nutrient uptake light harvesting and temperature dependence. Eight different functional groups of phytoplankton are simulated that differ in their surface area/volume, capability to fix nitrogen, use silica and regulate their buoyancy Upstate Freshwater Institute Markensten et al. NYWEA 2008 Size and Shape Influences Growth Temperature adaptation Light absorption Grazing Passive movement (up or down) Nutrient uptake not explicitly affected Upstate Freshwater Institute Markensten et al. NYWEA 2008 Upstate Freshwater Institute Markensten et al. NYWEA 2008 What is different in PROTECH? Morphological relationships describe growth: r 20 Reynolds (1989) Upstate Freshwater Institute Markensten et al. NYWEA 2008 (Reynolds in Sommer 1989) Temperature-sensitivity of growth rate (r ) as a function of s/v Upstate Freshwater Institute Markensten et al. NYWEA 2008 (Reynolds in Sommer 1989) Light effect on phytoplankton growth Upstate Freshwater Institute Markensten et al. NYWEA 2008 Overview of the hybrid 1D model including phytoplankton functional groups Upstate Freshwater Institute Markensten et al. NYWEA 2008 FeatureUFI ver 4.1UFI PROTECH hybrid Representation of phyto- plankton Carbon-based; constant stoichiometry; single (lumped) algae class Carbon-based; constant stoichiometry; multiple (eight) algae classes (PROTECH) NutrientsN, P.N, P, Si. ZooplanktonSpecified from measurements. Modeled. Suspended Solids FSS; VSS=Detritus + Algal material. VSS=Detritus + Algal material. Phytoplankton Settling Always downward at specified rate. Some phytoplankton may move up or down. ResuspensionWave-driven resuspension in littoral areas; flux computed from critical stress relationship. Complete resuspension of deposited algal particulates (Algal C) in mixed layer DepositionAt rate determined by settling velocity. Below mixed layer: determined by settling velocity. In mixed layer: no deposition. Sediment Release, Diagenesis Specified release rate of SRP (via TRP) and NH3; no transformation of deposited organic material. Release of SRP, NH3 and Si from phytoplankton at same rate as in the water column (respiration). Upstate Freshwater Institute Markensten et al. NYWEA 2008 Phytoplankton Functional Groups Large Filamentous diatoms - Aulacoseira Small diatoms Stephanodiscus Small Flagellates Cryptomonas Rhodomonas Large Flagellates - Ceratium Large non N fixing cyanobacteria - Microcystis Large N fixing cyanobacteria - Anabaena Aphanizomenon Upstate Freshwater Institute Markensten et al. NYWEA 2008 Expectations To simulate realistic seasonal patterns of chlorophyll and functional group biomass. To simulate inter annual variations in phytoplankton biomass The phytoplankton model was not tuned to local conditions Alometric coefficients influencing phytoplankton growth are those given by Reynolds. Minimal tuning of the sub-models describing hydrodynamics and nutrient kinetics. Model Calibration Upstate Freshwater Institute Markensten et al. NYWEA 2008 Measured PROTECH Results Comparison of Measured and Modeled Data 1998 Hydrothermal Model Upstate Freshwater Institute Markensten et al. NYWEA 2008 UFI 1D PROTECH- hybrid1D Measured Upstate Freshwater Institute Markensten et al. NYWEA 2008 Comparing hybrid model results with measurements Upstate Freshwater Institute Markensten et al. NYWEA 2008 Comparing hybrid model results with measurements Upstate Freshwater Institute Markensten et al. NYWEA 2008 Both models perform well in predicting chlorophyll on an annual scale, and also realistically simulated seasonal patterns in chlorophyll. The PROTECH hybrid model successfully simulated occurrence of major functional groups in the Cannonsville Reservoir. The model is a valuable tool for predicting seasonal variability in chlorophyll and phytoplankton functional groups Evaluation of the model using other reservoirs and longer time series of data is underway. Conclusions Upstate Freshwater Institute Markensten et al. NYWEA 2008 Baseline Delta Change based on ECAM A Cannonsville Isopleths Chlorophyll a (mg m -3 ) Water Temperature (C) Chlorophyll a (mg m -3 ) Upstate Freshwater Institute Markensten et al. NYWEA 2008