Human Health
Monterey Bay

photo of beach with a warning sign
Periodically there are beach warnings and closures, due to high bacteria levels (E. coli, fecal coliform, total coliform, Enterococcus). Credit: Becky Stamski, MBNMS, NOAA

Why is it a concern?

Offshore, nearshore, and estuarine environments in Monterey Bay National Marine Sanctuary have all been impacted by contaminants. Although the majority of the sanctuary’s nearshore waters generally do not pose risks to human health, there are localized areas and isolated impacts that periodically pose serious health risks. Because toxins (domoic acid and paralytic shellfish poison) produced by certain algal species have been found at levels in Monterey Bay that are potentially harmful to human health, and  an annual statewide mussel quarantine is issued from May 1 to October 31 by the California Department of Public Health.  Periodic beach warnings and closures, due to the presence of pathogen indicators (E. coli, fecal coliform, total coliform, Enterococcus), are common at some locations.

Other chemical contaminants found in the tissues of nearshore animals, and in some cases exceeding health standards, include DDT, PAHs, PCBs, arsenic, mercury, chlordanes, butyltins, and copper. Problem areas for metals and/or persistent organic pollutants (POPs) are at Elkhorn Slough, Moss Landing, Pacific Grove, and Santa Cruz Point. Approximately a third of the sanctuary sites sampled are categorized as high relative to all other U.S. sites for metals and/or POPs.

To improve time lags for posting closures and reopening beaches, research is needed to develop faster, reliable new methods of indicator bio-assessment, to investigate the use of indicator compounds other than coliform bacteria (e.g., fecal sterols, caffeine, long-chain alkylbenzenes), and to determine ways to distinguish between animal and anthropogenic sources of contamination (e.g., RNA ribotyping). In addition, a poor understanding of the dynamics of harmful algal blooms affects the ability to control causal mechanisms and reduce impacts.  Research is needed to distinguish human from natural influences that appear to be resulting in increased frequency and duration of outbreaks, particularly among strains of algae not recognized on the west coast until the early 1990s. 


Overview of Research

Research conducted by Sanctuary scientists and partners provides critical information to address existing and emerging resource conservation and management issues. The Overview of Research highlights some, but not necessarily all, of the research activities completed or ongoing at the Sanctuary.

Project Name PI and contacts Links

Fish Survey for toxics

California Office of Environmental Health Hazard Assessment

Swimming Safety

California Water Quality Monitoring Council

Preharvest Shellfish Protection and Marine Biotoxin Monitoring Program

California Department of Public Health

Health Advisories for CA Finfish, Shellfish and Crustaceans

California Department of Fish and Wildlife


Science Needs and Questions

  • Can compounds other than coliform bacteria (e.g., fecal sterols, caffeine, long-chain alkylbenzenes) be detected rapidly, and do they accurately indicate the presence of pathogens?
  • Do these methods have the speed to meet recreational users' needs, and the specificity to meet state water quality standards?
  • Can disease-causing pathogens be directly tested as an alternative to using indicators?
  • What systems are available to present real-time information on beach status to the public?
  • Are there other pollutants associated with indicator bacteria such as endocrine disruptors and other pharmaceuticals, and what are their effects to nearshore organisms?
  • What are reliable indicator species for the presence of HAB toxins (Emerita sp., Mytilus sp.)?
  • How do HABs affect local species populations?
  • What are the depuration rates for shellfish and other market organisms (e.g., rockfish, flatfish, baitfish) following HAB events?
  • What are the natural and anthropogenic factors influencing the HABs?
  • What are the other, non-filter feeding pathways that HABs impact the ecosystem, such as through contamination of flatfish or bait fish?
  • What role do agricultural versus urban nutrients play in the development of HAB events?
photos showing orange water due to harmful algal blooms
Harmful algal blooms (HABs) occur when microscopic algae (phytoplankton, often single cells) grow very rapidly under favorable conditions. HABs are noteworthy, in part, because some algal species have the ability produce toxins when they bloom, causing illness in marine mammals and humans alike. Caption: Credit: MBNMS, NOAA



Armstrong, M.A., N. Ladizinsky, W.P. Cochlan, R.M. Kudela. 2007. Nitrogenous preference of toxigenic Pseudo-nitzschia australis (Bacillariophyceae) from field and laboratory experiments. Harmful Algae 6:206-217.

Fritz, L., M.A. Quilliam, J.L.C. Wright, A.M. Beale, T.M. Work. 1992. An outbreak of domoic acid poisoning attributed to the pennate diatom Pseudonitzschia australis. Journal of Phycology 28:439-442.

Hunt J.W., B.S. Anderson, B.M. Phillips, P.A. Nicely, R.S. Tjeerdema, H.M. Puckett, M. Stephenson, K. Worcester, V. deVlaming. 2003. Ambient toxicity due to chlorpyrifos and diazinon in a Central California Watershed. Environmental Monitoring and Assessment 82:83-112.

Kimbrough, K.L., W.E. Johnson, G.G. Lauenstein, J.D. Christensen, D.A., Apeti. 2008. An assessment of two decades of contaminant monitoring in the nation’s coastal zone. Silver Spring, MD. NOAA Technical Memorandum NOS NCCOS 74 105pp.

Phillips, B., M. Stephenson, M. Jacobi, G. Ichikawa, M. Silberstein, M. Brown. 2002. Land use and contaminants. Pages 237-257 In: Caffrey, J., M. Brown, W.B. Tyler, M. Silberstein (eds.). Elkhorn Slough Foundation, Moss Landing, California.

Ricker J. and S. Peters. 2006. Assessment of sources of bacterial contaminations at Santa Cruz County Beaches. County of Santa Cruz, Water Resources Program. 75pp.

SWRCB (State Water Resource Control Board). 2006. 303(d) List of Water Quality Limited Segments. Electronic document available here.