Natural and anthropogenic stressors, such as climate change, disease or toxicants, can have widespread effects on ecosystem processes. Research at BML traces the effects of physiological and embryonic impairments to population and community level outcomes, and focuses on many species economically important to California fisheries (e.g., oysters, abalone, herring and salmon). BML researchers study the effects of classic contaminants as well as pollutants of emerging concern such as chemicals from plastics and personal care products. Disease studies are made possible by BML’s state-approved pathogen containment facilities.
BML researchers in toxicology, ecology, oceanography and veterinary science work together to develop a better understanding of the “zone of impact” of polluted runoff. Whether large outflows from bays, river plumes or small-volume discharge from urban drains, the impact on the ecosystem is greatest near the source and then decreases in the direction of water flow, decreasing at a rate largely determined by mixing of polluted waters with offshore ocean waters.
Contaminants in the Marine/Estuarine Environments
The BML Toxicology Laboratory (G.N. Cherr, Principle Investigator) has focused extensively on Pacific herring in San Francisco Bay in that they are key to the San Francisco Bay ecosystem and represent the last commercial fishery inside of the Bay. The BML Toxicology Group was the first to demonstrate that creosote-treated pier pilings (and the soluble polycyclic aromatic hydrocarbons; PAHs) present a danger to herring embryos when eggs are spawned directly on the piling surfaces. This research was utilized by the State of California in the decision to ban the use of any new creosote-treated pilings in waters of the State. In 2007, the BML group was approached by California State (Dept. of Fish and Wildlife) and Federal (NOAA) Trustees to collaboratively conduct the Natural Resources Damage Assessment for the Cosco Busan fuel oil spill in San Francisco Bay. Results from these field-based studies were remarkable in that unexpected high mortalities with complete cytolysis of embryos were observed at lightly oiled sites where herring had spawned in the intertidal zone. No significant mortalities were observed at non-oiled reference sites at the same tidal height. Furthermore, embryos outplanted at depth without sunlight exposure at the same oiled sites showed classic oil-related cardiac abnormalities but no cytolysis and mortality. These findings led to the conclusion that sunlight combined with the fuel oil to result in dramatic phototoxicity and this was published in the Proceedings of the National Academy of Scienes USA. A follow up study investigated the direct role of sunlight in bunker fuel oil phototoxicity and was published in PLoS ONE. This study demonstrated that phototoxicity of bunker fuel was much greater than Alaska North Slope crude oil and that the phototoxicity was probably due to compounds in bunker fuel other than PAHs.
In related research, the BML Toxicology Laboratory has investigated the effects of environmental contaminants that impair early development in invertebrates as well as lower vertebrates. Using the sea urchin embryo model system, they were the first group to demonstrate that individual PAHs and water-soluble creosote compounds disrupt the establishment of the embryonic axis. Establishment of the embryonic axis is highly conserved across phyla (worms to humans) and the Wnt/ß-catenin signaling pathway is responsible. The research demonstrating that PAHs can disrupt this pathway and cause nuclear ß-catenin accumulation is a newly described mechanisms of PAH toxicity and alters embryonic axis determination in a vertebrate system (zebrafish) as well.
The BML Toxicology Laboratory has been participating in a multidisciplinary center award (5 years and just renewed for another 5 years) from the NSF and the EPA that established the University of California Center for the Environmental Implications of Nanomaterials (UC CEIN), based at UCLA and UCSB. This center award has a number of multidisciplinary “themes” that range from chemical engineering to public perception of nanotechonology. At BML, the effort has been a collaborative one with scientists at UC Santa Barbara on the effects of engineered nanomaterials on estuarine and marine organisms. The physical behavior of different nanomaterials in environmental media indicated their behavior in seawater was quite different than freshwater and a collaboration with UC Santa Barbara and published in Nature Nanotechnology showed that nanomaterials could undergo biomagnification up the food chain. Very common metal oxide nanoparticles are highly toxic to developing sea urchin embryos, and may impact coastal marine ecosystems in ways previously not considered for adult organisms.
Endocrine Disruption in the Bay-Delta
The effects of endocrine disruptors on the reproductive biology of resident fish in the Sacramento-San Joaquin Delta have been studied at BML. Endocrine disruption in the inland silverside (Menidia spp.) has been the focus for a number or years since populations of native fish are so low and several are listed as endangered, Menidia is an ideal indicator species as they have a limited home range, are found across broad salinity gradients, and are reproductive for about 4-6 months. With support from both graduate and postdoctoral Delta Science Fellowships, investigations of endocrine disruption in different regions of the Delta using plasma egg chorion (egg coat) protein presence in males and immature fish as an indicator has been extremely useful. The focus has been on the common pyrethroid pesticides in the laboratory but a more multidisciplinary approach has been taken in the field where numerous stressors may contribute to endocrine disruption. The most recent publication in PLoS ONE shows endocrine disrupting chemicals have very different impacts at urban and ranch wastewater runoff sites. Changes in sex ratios and other population parameters such as growth and time to reproduction are affected by environmental estrogens and androgens.
Findings from the SHL have been critical to the State of California and these include:
- Demonstrating the susceptibility of red abalone at San Miguel Island to disease-induced mortality during El Nino events. An experimental commercial fishery is being considered for this population and the study results can be incorporated into fishery design models.
- Showed that green abalone are resistant to the disease withering syndrome, and are therefore a good species on which to focus recovery efforts for abalone in the southern California bight.
- Tracked the northerly spread of the agent of abalone withering syndrome into populations subject to the red abalone recreational fishery.
- Monitored the health of captive populations of the federal ESA-listed white abalone that are being held for use in the species’ recovery program.
- Developed an oxytetracycline antibiotic delivery method that is capable of completely eliminating the agent of abalone withering syndrome in captive abalone populations being used in species recovery programs. We then successfully used this method to treat captive populations of the endangered white abalone being held at four facilities located throughout California, including BML.
- Demonstrated the success of the eradication effort for an introduced sabellid polychaete worm among intertidal snail populations near the outfall of an abalone farm. The non-native worm had become established in the snail population in the early 1990s and eradication was attempted in 1996 via removal of infested snails. We demonstrated success of that effort by showing its absence in nine consecutive years of sampling.
- Certified four abalone holding facilities as free of the sabellid polychaete, allowing them to participate in outplanting efforts for abalone recovery programs.
- Determined patterns of colonization, growth, reproduction and pathogen presence in native oysters settled onto mounds of oyster shell experimentally outplanted in San Francisco Bay.
- Examined over 1300 samples from waterbodies from throughout California for the presence of planktonic larval stages of invasive quagga and zebra freshwater mussels.
- Determined that planktonic larval stages of the quagga mussel can survive for more than five days in single droplets of water, demonstrating risk of transfer of the species between waterbodies with movement of recreational vessels.
- Continued our ongoing role in regulating shellfish importations and transfers for aquaculture and research purposes.
Plumes and Coastal Water Quality
John Largier has been collaborating with pathologists and wildlife health researchers in the UCD Vet School, producing a collection of papers on the transport of water-borne pathogens, including particle aggregation dynamics and plume dynamics. This information is critical for understanding how human and non-human pathogens are transported from land to the sea.