A new tool for tracking algal toxins is under development. The tool resembles a tea bag filled with sand and, like a tea bag, is soaked in water. The grains in the sac, though, are actually tiny porous resin beads that selectively absorb domoic acid, a naturally occurring neurotoxin that causes amnesic shellfish poisoning in people and brain seizures in marine mammals.

The UC Santa Cruz scientists leading this project envision hanging the “tea bags” off piers and wharfs in California to continuously track algal toxin levels. The idea is similar to what is already being done through the state’s sentinel “mussel watch” program, except that the “tea bags” can detect lower levels of toxins and are unaffected by harmful algal blooms and pollution that can kill living organisms.

Ultimately, scientists would like to use ocean-monitoring data in conjunction with the algal tracking technology to forecast algal blooms based on observed environmental conditions.

Harmful algal blooms (HABs) are an escalating problem in coastal ecosystems, inflicting massive economic losses on commercial fisheries and causing death and illness to both humans and marine fauna. Paralleling the rise of marine HAB problems, cyanobacteria (previously identified as "blue-green algae") have a worldwide distribution and can form extensive blooms in freshwater and estuarine habitat. Microcystins are fast becoming a global health concern, with severe and recurrent blooms with toxin elaboration reported globally, including central California. Until recently, microcystin intoxication was considered a public health issue mainly of freshwater habitat, reflected by the vast body of published literature on potential human health risks due to microcystin exposure in rivers, lakes, reservoirs and freshwater aquaculture. In contrast, monitoring of marine water and seafood for similar risks has been limited, despite confirmation of outflows of microcystin-contaminated freshwater to the ocean. A passive sampling method for determination of dissolved toxins in seawater, Solid Phase Adsorption Toxin Tracking (SPATT), allows for field-deployment of adsorbent resin sealed within a polyester mesh bag and have been used for a suite of lipophilic toxins, but until recently have never been evaluated for use with hydrophilic (water-soluble) toxins such as domoic acid (amnesic shellfish poisoning) and saxitoxin (the primary toxin associated with paralytic shellfish poisoning).

THE ENVIRONMENTAL PARAMETERS AND TRENDS DRIVING TOXIGENIC ALEXANDRIUM CATENELLA BLOOMS IN MONTEREY BAY, CALIFORNIA FROM 2001-2019by Regina L. Radan

An 18-year data set of samples collected weekly from the Santa Cruz Municipal Wharf (SCW) in Santa Cruz, California, was used to investigate the environmental parameters driving Alexandrium catenella abundance and toxicity in northern Monterey Bay, California. Alexandrium catenella is the causative organism for Paralytic Shellfish Poisoning (PSP) in California coastal waters and is routinely monitored. A semi-quantitative index of relative abundance and quantitative cell counts of A. catenella (cells L-1) reveals an increase in relative and absolute abundance of A. catenella from 2003-2007, and again from 2016-2019. Using a Generalized Linear Model (GLM), both annual and seasonal models were developed using 12 biological and physical parameters to explain the dependent variables, A. catenella abundance, and Paralytic Shellfish Toxins (PST) concentration. Together, (-) NO3- (µM) and sea surface temperature (ºC) (p = 0.0031), (-) San Lorenzo River discharge (m-3s-1) (p = 0.0002), and (+) chlorophyll-a (µg L-1 ) (p <0.0001), were all strongly correlated with the presence of A. catenella at the SCW in the annual model. Spring and fall/winter models showed similar patterns. Blooms of A. catenella are defined as abundances greater than one standard deviation from the climatological mean (1349 cells L-1). Blooms were strongly correlated with (-) San Lorenzo River discharge (p = 0.0192) and (+) chlorophyll-a (p < 0.0001) in the annual model but showed different patterns for the seasonal models. When lagging PSTs by three weeks, the annual model identified a strong negative correlation with NO3- and a positive correlation with sea surface temperature (ºC) (p=0.0024). This study demonstrates the importance of examining more than one environmental factor when determining the drivers for toxic blooms. These models could potentially be used to forecast future blooms and the presence of PSTs in Monterey Bay, California, and elsewhere where dinoflagellates are common members of the phytoplankton assemblage.

Ocean-monitoring satellite and airborne sensors are important for characterizing aquatic ecosystems spatially. These above-water sensors measure light radiating from the sea surface, from which they estimate biogeochemical properties with the help of optical algorithms. To ensure their reliability, radiometric and biogeochemical data products must be validated in-situ across the ecosystems that they characterize. This in-situ validation is typically carried out using ground truth radiometric measurements collected using in-water optical profilers. Our ability to validate above-water sensors using profilers alone, however, is limited, especially in coastal and inland ecosystems. Here we seek to improve the validation of these sensors and their data products in coastal and inland ecosystems. I demonstrate that modeling is an important tool for expanding our capability to reliably validate satellite and airborne sensors, as well as to identify for which ecosystems specific optical algorithms are likely to work. With the advent of next-generation satellites and unmanned aerial vehicles with better spatial and spectral resolution, my research contributes to an improved understanding of coastal and inland ecosystems, as well as their ever-changing dynamics.

Seasonal blooms of Pseudo-nitzschia spp., along with corresponding seasonal increase/decrease in domoic acid concentrations, consistently occur in the waters surrounding the Santa Cruz Municipal Wharf. Domoic acid has been intermittently observed in the water column when Pseudo-nitzschia spp. are not present, and presence or absence of cells is generally a poor indicator of toxin concentration in the water and sentinel mussel samples. Chlorophyll a and domoic acid values from seawater, sediment and Solid Phase Adsorption Toxin Tracking (SPATT) samples from February through December 2013 were analyzed and compared to a long-running weekly time series at the Santa Cruz Municipal Wharf, part of the California Department of Public Health monitoring program, to investigate retention of domoic acid in the sediments. We hypothesized that domoic acid concentrations in the sediment would increase immediately following a Pseudo-nitzschia bloom and increased domoic acid concentrations in the water column would follow a mixing event due to sediment and bottom water resuspension. Despite the lack of a significant toxic algal bloom during the study period, domoic acid was consistently observed at the sediment-water interface. Peaks of domoic acid concentrations in SPATT samples preceded peaks of particulate domoic acid from seawater samples, suggesting that the domoic acid source was more closely associated with the sediment-water interface. Sediment resuspension is a likely origin, suggesting that the sediment is potentially acting as a reservoir for domoic acid. It may be important for public health monitoring programs to include a sediment toxin analysis, particularly given the known presence of domoic acid in commercially harvested benthic organisms, such as crabs and flatfish.

The generalized bio-optical transition from oligotrophic blue to mesotrophic green waters has enabled remote measurement of oceanic ecosystems under conditions in which the optically relevant water mass constituents covary with the primary phytoplankton photopigment, chlorophyll a (Chla). This assumption, known as case-1, is generally incorrect within coastal and inland water bodies, where external factors, such as riverine discharge and sediment resuspension, also modify the concentrations of organic and inorganic constituents beyond the ranges anticipated for natural oceanic ecosystems. New approaches to characterize aquatic ecosystems without relying on case-1 criteria are proposed here using measurements of apparent and inherent optical properties. The methods applied in this work include bio-optical modeling and analyses of in situ, airborne, and satellite radiometric measurements of oceanic, coastal, and inland water ecosystems. Key findings are that: satellite phytoplankton datasets underestimate phytoplankton biomass in coastal ocean regions when default atmospheric correction methods are applied (Chapter 1); the expansion of spectral range for above-water radiometric measurements improves the accuracy of colored dissolved organic matter algorithms (Chapter 2); and hyperspectral beam-attenuation meters can accurately predict Chla without relying on empirical relationships between organic and inorganic particle populations (Chapter 3). The bio-optical advances presented here improve measurement capabilities for optically complex waters and are relevant to global (i.e., oceanic, coastal, and inland) water bodies. Finally, this work supports the perspective that bio-optical approaches should be consistent with electromagnetic theory or other fundamental principles - rather than requiring a partition between waters that satisfy versus fail empirical open ocean criteria - to incorporate a greater diversity of global aquatic ecosystems.

Diarrhetic Shellfish Poisoning Toxins (DSTs) are produced by the marine dinoflagellate, Dinophysis. DSTs can bioaccumulate in shellfish and cause gastrointestinal illness when humans consume high levels of this toxin. Although not regulated in the U.S., recent studies in Washington, Texas, and New York suggest DSTs may be widespread throughout U.S. coastal waters. This study describes a four-year time series (2013-2016) of Dinophysis concentration and DST level in California mussels (Mytilus californianus) from Santa Cruz Municipal Wharf (SCMW) in Monterey Bay, California. Results show a maximum Dinophysis concentration of 9,404 cells/L during this study and suggest Dinophysis persists as a member of the background phytoplankton community throughout the year. DSTs in California mussels were found in persistent low levels throughout the course of this study, and exceeded the FDA action level of 160 ng/g 19 out of 192 weeks sampled. Dinophysis concentrations alone are a positive but weak predictor of DST level in California mussels, and basic environmental variables (temperature, salinity, and nutrients) do not sufficiently explain variation in Dinophysis concentration at SCMW. Overall, this study demonstrates that Dinophysis concentrations on the central coast of California, at SCMW, are producing DSTs that accumulate in local shellfish throughout the year, occasionally reaching levels of concern.

In this dissertation, I address the implications of a poly-species invasion consisting of a mud snail (Batillaria attramentaria) and the novel trematode parasite that uses the snail as a host, and I characterize the effects of this invasion on organic matter cycling in Elkhorn Slough. In Chapter 1, I used field transect surveys and a mark-recapture experiment to show that trematodes induced snails to increase growth and alter their habitat use. In Chapter 2, I used a field enclosure experiment to investigate the effects of parasitic modifications to Batillaria on the snail’s food resources and on sediment chemistry, showing that parasitic effects on snails have profound effects on benthic community structure and function. In Chapter 3, I investigated Batillaria’s interactions with a bloom-forming macroalga. I used a laboratory experiment to show that the snail could facilitate the algae by increasing its growth in nutrient-replete water, and allowing it to persist in low-nutrient water, potentially exacerbating blooms that cause hypoxia and other ecological problems. My dissertation underscores the context-dependency of ecological interactions, and highlights interactions that should be more widely recognized in forward-thinking ecosystem management.

Microcystin toxin is a known environmental stressor with implications for ecosystem harm throughout many inland waterways in California. This purported freshwater toxin has recently emerged in the marine environment in Monterey Bay. Microcystin abundance and frequency, as well as environmental variables that drive toxin production in the Monterey Bay area were examined by deploying Solid Phase Adsorption Toxin Tracking (SPATT) samplers and evaluating water samples for 3 years. Microcystin was found in 15 of 21 monitored sites and was shown to be correlated with anthropogenic nutrient loading. Because it is relevant to identify an indicator organism to better monitor this toxin, uptake and release of microcystin toxin in California mussels (Mytilus californianus), and commercial oysters (Crassostrea sp.) were also examined. To provide environmental relevancy Mytilus sp. were also collected at 4 sites in San Francisco Bay for 6 months and analyzed for microcystin toxin. The results indicate that mussels purge microcystin toxin slowly, while oysters released toxin more quickly, however, both have the ability to retain toxin for 8 weeks post-exposure. To investigate potential effects to marine and estuarine birds at upper trophic levels the use of Whatman® FTA® blood sample collection cards were evaluated in tandem with competitive enzyme-linked immunosorbent assay (ELISA), and this method was shown to have utility for postmortem analysis and large die off events. Blood was also collected from birds admitted to rehabilitation in Monterey Bay between 2011-2015 and two groups of waterbirds tested positive for microcystin toxin. The extensive manifestation of microcystin in the Monterey Bay area exhibits the need for better monitoring and management of this toxin. Management decisions made at the terrestrial level, may now impact freshwater, estuarine, and marine ecosystems, particularly given the demonstrated capacity for bio-accumulation in shellfish. The identification of a potential bio-indicator through this study, could be used to inform the current Mussel Watch Program or could aid in establishing an analogous monitoring program specific to this toxin. Because current data on the effects of toxic algae on waterbirds is meager, this study addresses this deficiency by identifying a new technique for detecting microcystin in upper trophic levels.