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TEMPORAL DYNAMICS OF CYANOBACTERIA BLOOMS IN THREE RHODE ISLAND PONDS
Citation:
Shivers, S., B. Kreakie, Jeff Hollister, S. Fournier, AND W. Milstead. TEMPORAL DYNAMICS OF CYANOBACTERIA BLOOMS IN THREE RHODE ISLAND PONDS. 12th National Monitoring Conference, NA, Virtual, April 19 - 23, 2021.
Impact/Purpose:
Cyanobacteria are found naturally in freshwater ecosystems and can form blooms under favorable conditions. These harmful algal blooms (cHABs) may be toxic and can affect human and environmental health. A better understanding of how and why blooms form is needed to predict bloom formation. This study investigated temporal dynamics of cHABS in three Rhode Island ponds with different land uses (urban vs. forested). There were differences between the ponds with the urban ponds blooming while the forested pond did not. Preliminary analysis indicates that temperature may be an important driver for these blooms.
Description:
Cyanobacteria are natural components of freshwater ecosystems that can form blooms when conditions are favorable (e.g., high nutrient inputs). These harmful cyanobacteria blooms (cHABs) are detrimental to human and environmental health and can impact ecosystem function and services. The purpose of this study is to investigate the temporal dynamics of cHABs in three ponds with different land use (high-density urban vs medium-density urban vs forested). Seven sites were sampled in each pond, weekly or twice weekly (during blooms), between June and December 2018-2019. Physical parameters (temperature, DO, pH, conductivity) were measured at 1 m intervals using a YSI sonde and 2 m integrated water samples were collected for chlorophyll a, phycocyanin, and turbidity. Nutrients were measured at the deepest site in each pond (TN, TP, NO3-N, NH4-N, PO4-P). The forested pond did not bloom and chlorophyll a remained low (avg. annual mean = 3.4 ug/L) throughout the study. The high-density urban pond had high chlorophyll a and phycocyanin in 2018 and 2019 indicating a cHAB; indeed, health advisories were issued during both years. The medium-density urban pond had high chlorophyll (> 40 ug/L) and low phycocyanin, indicative of a bloom from a source other than cyanobacteria. There were interannual differences in bloom timing, duration, and magnitude for both urban ponds, and preliminary analysis indicates temperature may be a primary driver. Bloom indicators from these contrasting ponds are being evaluated as potential predictors to develop a probabilistic model for predicting cHABs.
