Mortality of Endangered Juvenile Lost River Suckers Associated with Cyanobacteria Blooms in Mesocosms in Upper Klamath Lake, Oregon

Abstract

Unsustainably high mortality within the first 2 years of life prevents endangered Lost River Suckers Deltistes luxatus in Upper Klamath Lake, Oregon, from recruiting to spawning populations. Massive blooms of the cyanobacterium Aphanizomenon flos-aquae and their subsequent death and decay in the lake (bloom-crashes) are associated with high pH, low percent oxygen saturation, high total ammonia concentrations, and spikes in the cyanotoxin microcystin. Poor water quality within the lake is considered the most likely cause of juvenile sucker mortality, but mechanisms causing the high mortality are not known. We introduced PIT-tagged age-1 Lost River suckers into three continuously monitored mesocosms in Upper Klamath Lake to determine the timing of juvenile sucker mortality relative to pH, temperature, and dissolved oxygen. Mortality was inferred from a lack of movement detected on remote PIT tag detection equipment within each mesocosm. Mortality was compared among mesocosms and an indoor tank-held control group. We fitted time-varying Cox hazard models to test hypotheses about short-term and chronic effects of single

Does the Kis-Balaton Water Protection System (KBWPS) Effectively Safeguard Lake Balaton from Toxic Cyanobacterial Blooms?

“…During the whole investigated period, pH was above the proposed guideline of 9. High water alkalinity has many times been associated with cyanobacterial blooms [ 42 , 43 , 44 ]. As for dissolved oxygen and oxygen saturation, these values were within the guidelines during April, however, they started to drop significantly in May, while reaching their lowest values in September.…”

Contribution of warm habitat to cold‐water fisheries

“…Concurrently, the dominant algae‐like species has shifted to Aphanizomenon flos‐aquae cyanobacteria (Bradbury et al., 2004; Eilers et al., 2004). Every summer, A. flos‐aquae blooms push alkalinity and dissolved oxygen to levels that prove stressful or lethal for fishes, including taxa that are more tolerant than salmonids (Burdick et al., 2020; Perkins et al., 2000). Thus, the lake emulates 2 commonly predicted outcomes of climate change, high maximum temperatures (Isaak et al., 2015) and eutrophic conditions (Lu et al., 2019; Sinha et al., 2017).…”

Tracking Fisheries Through Time: The American Fisheries Society as a Historical Lens

“…A growing concern for the health of humans and fisheries focuses on toxic algal blooms caused by excess nutrients and soil from non-point source pollution runoff (Davis et al 2019). For example, the high mortality rates of endangered Lost River Suckers Deltistes luxatus in Upper Klamath Lake, Oregon are associated with cyanobacteria blooms, but identifying a direct link from poor water quality to mortality is complicated (Burdick et al 2020). In 2020, the regressive action of redefining the extent of "Waters of the United States" by restricting the Clean Water Act jurisdiction to fewer waters means that more waters and fish species dependent on those waters will be increasingly at-risk from diminished federal protection (Colvin et al 2019).…”