Associations between Water Physicochemistry andPrymnesium parvumPresence, Abundance, and Toxicity in West Texas Reservoirs

Abstract

Toxic blooms of golden alga (Prymnesium parvum) have caused substantial ecological and economic harm in freshwater and marine systems throughout the world. In North America, toxic blooms have impacted freshwater systems including large reservoirs. Management of water chemistry is one proposed option for golden alga control in these systems. The main objective of this study was to assess physicochemical characteristics of water that influence golden alga presence, abundance, and toxicity in the Upper Colorado River basin (UCR) in Texas. The UCR contains reservoirs that have experienced repeated blooms and other reservoirs where golden alga is present but has not been toxic. We quantified golden alga abundance (hemocytometer counts), ichthyotoxicity (bioassay), and water chemistry (surface grab samples) at three impacted reservoirs on the Colorado River; two reference reservoirs on the Concho River; and three sites at the confluence of these rivers. Sampling occurred monthly from January 2010 to July 2011. Impacted sites were characterized by higher specific conductance, calcium and magnesium hardness, and fluoride than reference and confluence sites. At impacted sites, golden alga abundance and toxicity were positively associated with salinity-related variables and blooms peaked at~10°C and generally did not occur above 20°C. Overall, these findings suggest management of land and water use to reduce hardness or salinity could produce unfavorable conditions for golden alga. (KEY TERMS: algae; aquatic ecology; harmful algal blooms; watershed management.) VanLandeghem, Matthew M., Mukhtar Farooqi, Greg M. Southard, and Reynaldo Patiño, 2015. Associations between Water Physicochemistry and Prymnesium parvum Presence, Abundance, and Toxicity in West Texas Reservoirs.

Climate-water quality relationships in Texas reservoirs

“…In general, water temperature (and dissolved oxygen) tended to be positively (and negatively) correlated with shorter‐term indicators related to average and cold air temperatures over periods ranging from 1 to 4 weeks. Association between air temperature and dissolved oxygen and the effect on aquatic habitat has been documented in other studies (Hassan et al ., ; Kling et al ., ; Deng and Patil, ; Patiño et al ., 2014; Van Landeghem et al ., ). Precipitation is not correlated with water temperature and dissolved oxygen in deseasonalized data.…”

“…This is consistent with the fact that precipitation dilutes salts in water, leading to lower concentrations. For example, in 2010–2011, during a particularly dry period in Texas, reservoir storage decreased, while salinity increased in multiple reservoirs of the Upper Colorado River, in West Texas, with a trend reversal during a major precipitation inflow event in the fall of 2012 (Van Landeghem et al ., ). These parameters also tended to be positively correlated with long‐term temperature, likely as a result of higher temperatures leading to increased evaporation, which increases salt concentrations in the remaining water.…”

“…A number of studies have documented (but not attributed) observed trends in water quality in rivers and reservoirs of Texas. These include White Rock Lake (Brandbury and VanMetre, ; Van Metre and Callender, ), Trinity River (Van Metre and Callender, ), Rio Grande (DeYoe, ; Miyazono et al ., ), Broken Bow Lake (Carroll et al ., ), Brazos River and its reservoirs (Van Landeghem et al ., ), Colorado River and its reservoirs (Van Landeghem et al ., ,b), reservoirs in the Brazos and Colorado Rivers (Patiño et al ., 2014; Dawson et al ., in review), and streams from Northeast Texas (Taylor et al ., ). The impact of hydropower on water quality has been evaluated by Ashby et al .…”

Predicting the risk of toxic blooms of golden alga from cell abundance and environmental covariates

“…These data were collected during standard water quality monitoring; a state‐wide golden alga survey conducted in Texas; and routine monitoring of golden alga‐impacted lakes and reservoirs. In addition, original abundance and toxicity data collected during previous projects (VanLandeghem et al 2015a,b) were included in the current analysis. In all cases, golden alga abundance was determined from hemocytometer counts following the methods of Southard (), and ichthyotoxicity was determined using a standard fathead minnow ( Pimephales promelas ) larva bioassay (Southard ).…”

“…Results of these laboratory studies and others have led to the conclusion that toxicity is poorly correlated with the abundance of golden alga cells in cultures (e.g., Baker et al ; Brooks et al ). In the field, temperature and salinity have been shown to influence toxicity (Roelke et al ; Patiño et al ; VanLandeghem et al ). Toxicity was also associated with pH in some (Prosser et al ; Roelke et al ) but not all (Patiño et al ) studies of the Brazos River basin, Texas.…”