Transfer of microcystin from freshwater lakes to Puget Sound, WA and toxin accumulation in marine mussels (Mytilus trossulus)

Blooms of toxic cyanobacteria in freshwater ecosystems have received considerable attention in recent years, but their occurrence and potential importance at the land-sea interface has not been widely recognized. Here we present the results of a survey of discrete samples conducted in more than fifty brackish water sites along the coastline of southern California. Our objectives were to characterize cyanobacterial community composition and determine if specific groups of cyanotoxins (anatoxins, cylindrospermopsins, microcystins, nodularins, and saxitoxins) were present. We report the identification of numerous potentially harmful taxa and the co-occurrence of multiple toxins, previously undocumented, at several locations. Our findings reveal a potential health concern based on the range of organisms present and the widespread prevalence of recognized toxic compounds. Our results raise concerns for recreation, harvesting of finfish and shellfish, and wildlife and desalination operations, highlighting the need for assessments and implementation of monitoring programs. Such programs appear to be particularly necessary in regions susceptible to urban influence.

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Multiple Stressors at the Land-Sea Interface: Cyanotoxins at the Land-Sea Interface in the Southern California Bight

Tatters

Howard

Nagoda

et al. 2017

“…As a consequence, the accumulation of transferred MCs was described in marine fauna such as sea otters and shellfish [11][12][13]. The occurrence of M. aeruginosa and/or MCs in brackish waters was reported in many locations in the United States, South America, Australia, Europe including France, Japan, or India [14][15][16][17][18][19][20] and even became recurrent in San Francisco Bay, USA [21] and in the Patos Lagoon, Brazil [22]. Long-term survey and model predictions pointed out the positive impact of climate change on the intensity and frequency of this phenomenon through the intensification of precipitation and longer drought periods [15,16,23,24].…”

Section: Introductionmentioning

confidence: 99%

Salt Shock Responses of Microcystis Revealed through Physiological, Transcript, and Metabolomic Analyses

Aulnois

Réveillon

Robert

et al. 2020

The transfer of Microcystis aeruginosa from freshwater to estuaries has been described worldwide and salinity is reported as the main factor controlling the expansion of M. aeruginosa to coastal environments. Analyzing the expression levels of targeted genes and employing both targeted and non-targeted metabolomic approaches, this study investigated the effect of a sudden salt increase on the physiological and metabolic responses of two toxic M. aeruginosa strains separately isolated from fresh and brackish waters, respectively, PCC 7820 and 7806. Supported by differences in gene expressions and metabolic profiles, salt tolerance was found to be strain specific. An increase in salinity decreased the growth of M. aeruginosa with a lesser impact on the brackish strain. The production of intracellular microcystin variants in response to salt stress correlated well to the growth rate for both strains. Furthermore, the release of microcystins into the surrounding medium only occurred at the highest salinity treatment when cell lysis occurred. This study suggests that the physiological responses of M. aeruginosa involve the accumulation of common metabolites but that the intraspecific salt tolerance is based on the accumulation of specific metabolites. While one of these was determined to be sucrose, many others remain to be identified. Taken together, these results provide evidence that M. aeruginosa is relatively salt tolerant in the mesohaline zone and microcystin (MC) release only occurs when the capacity of the cells to deal with salt increase is exceeded.

“…Concerns of ecological and human health risks of cyanotoxins also extend beyond freshwater habitats and into the land-sea interface. Multiple studies in central California and one in Washington State have documented microcystins in marine outflows, with direct impacts in marine ecosystems far downstream of their biological origin [ 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 ]. The mass mortality of more than 30 marine sea otters in Monterey Bay was attributed to microcystin intoxication from ingestion of contaminated shellfish [ 45 ].…”

Section: Introductionmentioning

confidence: 99%

“…Microcystin production originated in Pinto Lake, a eutrophic water body that experiences frequent cyanobacterial blooms and drains to Monterey Bay via a 15-km segment of the Pájaro River [ 45 , 48 ]. Extensive watershed studies conducted in Monterey Bay, California and Washington State showed that this downstream transport of microcystins was a persistent and prevalent issue throughout the watershed (not just from a single waterbody) and that the toxins accumulated in marine shellfish [ 42 , 43 , 47 ]. These studies underscore an important role of rivers and streams as conduits that can not only produce cyanotoxins, but can also transport intact toxins from inland waters to downstream marine and estuarine waterbodies.…”

Section: Introductionmentioning

confidence: 99%

Microcystin Prevalence throughout Lentic Waterbodies in Coastal Southern California

Howard

Nagoda

Kudela

et al. 2017

Toxin producing cyanobacterial blooms have increased globally in recent decades in both frequency and intensity. Despite the recognition of this growing risk, the extent and magnitude of cyanobacterial blooms and cyanotoxin prevalence is poorly characterized in the heavily populated region of southern California. Recent assessments of lentic waterbodies (depressional wetlands, lakes, reservoirs and coastal lagoons) determined the prevalence of microcystins and, in some cases, additional cyanotoxins. Microcystins were present in all waterbody types surveyed although toxin concentrations were generally low across most habitats, as only a small number of sites exceeded California’s recreational health thresholds for acute toxicity. Results from passive samplers (Solid Phase Adsorption Toxin Tracking (SPATT)) indicated microcystins were prevalent throughout lentic waterbodies and that traditional discrete samples underestimated the presence of microcystins. Multiple cyanotoxins were detected simultaneously in some systems, indicating multiple stressors, the risk of which is uncertain since health thresholds are based on exposures to single toxins. Anatoxin-a was detected for the first time from lakes in southern California. The persistence of detectable microcystins across years and seasons indicates a low-level, chronic risk through both direct and indirect exposure. The influence of toxic cyanobacterial blooms is a more complex stressor than presently recognized and should be included in water quality monitoring programs.