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Sunset Fishing
Quick-Links Addit-Projects

quick links to projects & Interests:

1) California Scorpionfish and Blood-Sucking Parasites. 

 Is Disruption of the Adrenal Endocrine System Causing Problems with the Physiology of Defense?

2) Combining Research with Education. 

 Preliminary Study of Possible Environmental Endocrine Disruption in White Croaker of Los Angeles Harbor Area

3) Pollution Impacts in Orange County Surfing Country

4) Environmental Chemicals & Endocrine Disruption in San Francisco Bay Fish

5) Studies of Male Fish With High Estrogen Levels in Santa Monica Bay.

6) Impacts of Wetlands Restoration of Colorado Lagoon in Long Beach

7) New Technologies in Evaluating Watershed Health

     (San Gabriel River Watershed)

Cal Scorpiofish-stress-parasites

California Scorpionfish and Blood-Sucking Parasites

Is Disruption of the Adrenal Endocrine System Causing Problems with the Physiology of Defense? 

Scorpionfish Face pic.JPG

California Scorpionfish in its natural environment offshore of Orange County, California.

Dr. Juli Kalman-Passarelli working with a caught California Scorpionfish, exercising caution to avoid stinging by specialized fins.

In an intriguing research project undertaken with collaborating scientists, Dr. Juli Kalman-Passarelli (Exhibits and Collections Curator, Los Angeles Cabrillo Marine Aquarium) and Dr. Jeffrey Armstrong (Environmental Supervisor, Orange County Sanitation District), it has been shown that California Scorpionfish (Scorpaena guttata) with impaired adrenal endocrine systems had significantly higher rates of infestation by parasites.  The fish showed this endocrine disruption and associated parasitic infestations at 'urban-impacted' coastal locations such as boat harbors and near wastewater treatment plant (WWTP) discharge areas.  

California scorpionfish (and other fish species) "fight off" parasites using several strategies including physiologically, like immune responses, but they seem to always have some parasites.  They may show as many as 8 different parasite species ranging in prevalence from 0.5% by Isopods like Elthusa californica to 88.4% by Copepods like Lepeophtheirus rotundipes


The research found that the parasitic copepod, Naobranchia scorpaenae (shown in figure) exhibited a range of intensity from 0-321 on individual Scorpionfish and an overall prevalence of 78.2%.  It was not uncommon to find fish with more than 100 on their gill filaments.  As shown in the picture, these parasitic copepods bury their specialized hooks deep into gill filaments where they suck the blood as food.  Not a comfortable sight!

Scorpionfish open gill parasitized pic.J

Open gill chamber of Scorpionfish infested with the copepod, Naobranchia scorpaenae.

Scorpionfish gill filament infested pic.

Copepods (N. scorpaenae) "tapped" into blood vessels of a gill.

Scorpionfish close-up gill infestation.J

Several N. scorpaenae embedded in gill of infested California Scorpionfish

Scorpionfish parasite infestation microg

Microscopic view of copepod blood sucking apparatus penetrating a gill.

The research showed that such parasitic infestations and cortisol responses are inversely related.  As shown in graphic below, Scorpionfish from reference areas ("T-11" group) had low parasite abundance and a robust stress-induced cortisol response.  However, in fish sampled from impacted areas (WWTP outfall "T1" and impacted boat marina "T3" areas), cortisol production was impaired by more than 80%  (as compared to reference fish) which was significantly correlated with 4-fold higher indices of parasitic infestation.

Increased parasitic infestation of fish collected from polluted areas suggests that the fish may have compromised defense systems.  Current scientific knowledge on the type of endocrine disruption described here is very limited, yet it appears to have significant potential to seriously impair wild species of fish. 

Scorpionfish cortisol vs parasite data g

Further Info from the Scientific Literature

Effects of stress and cortisol on immune and defense functions have been well documented in the scientific literature (Schreck et al., 1993; Weyts et al., 1999; Schreck and Maule, 2001; Small and Bilodeau, 2005).  For example, Davis et al. (2002) reported that handling stress increased susceptibility to the protozoan parasite, Ichthyophthirius multifiliis.  Some studies in the literature have suggested that stress resulting from pollutant exposure impacts immune responses in fishes, increasing their susceptibility to parasites and disease (Ellis, 1981; Bly et al., 1997; Jobling and Tyler, 2003; Hecker and Karbe, 2005). 

Wh Croaker-T3 study

Combining Research with Education: Preliminary Study of Possible Environmental Endocrine Disruption in White Croaker in Los Angeles Harbor Area

PCEC worked in collaboration with the Cabrillo Marine Aquarium (in San Pedro, California) to offer a summer educational program in which local students engaged in field research.  This work was aimed at determining whether a native fish species, white croaker (Genyonemus lineatus), may be exhibiting evidence of environmental impacts, such as differences in hormone levels...possible "endocrine disruption"? 

White croaker sampled from the vicinity of Cabrillo Beach in the midst of the highly impacted Los Angeles Harbor were compared with white croaker sampled from Redwood City in the San Francisco Bay Area, considered a relatively "cleaner" site (see prior work relating to San Francisco Bay here).  The initial results (see data tables below) showed that croaker from the Redwood City location had an average concentration of thyroid hormone (triiodothyronine, or "T3") of 28.29 pg/ml, which was significantly higher than in white croaker from Cabrillo (18.91 pg/ml).  This preliminary work, involving two students, suggests that white croaker from Los Angeles Harbor may have depressed thyroid function, which could pose a risk to the animal's health and well being. Thyroid hormones are essential for growth and development in all vertebrates.  More research is needed.


​This preliminary work shows the value of combining education with real-world research, and provided rationale for future follow-up research to determine the degree to which this may continiue to be documented and whether it poses a health concern.


All researchers, students and staff, would like to thank all the fishermen that helped by allowing sampling of their caught fish!

Orange Couny Research




  • PCEC has worked with the Environmental Laboratory of the Orange County Sanitation District (OCSD) for about two decades, to assist in determining the degree to which fish health may be impacted by contaminant chemicals known to be present at selected locations offshore of this highly populated region of California.

  • Studies have centered on locations near Huntington Beach and Newport Beach known to be impacted by the OCSD outfall, as well as the  Newport Harbor and Dana Point.

  • The work is particularly focused on understanding physiological and health effects that may be linked to specific environmental chemicals.

  • The principal fish species in focus are the English sole and the hornyhead turbot, although other species of flatfish as well as California Scorpionfish are also evaluated (for an interesting study on scorpionfish, follow this LINK)

  • Fish have been found to have a variety of human-derived chemicals in their tissues, including pesticides, drugs, PCBs, DDTs, PAHs, PBDEs and others.  For more information on envionmental chemicals, click this LINK.

  • Directly associated with exposure of these animals to environmental contaminants have been multiple examples of physiological impacts, like endocrine disruption, among others.  These alterations likely pose risk to the health and well-being of fish.

  • We appreciate the environmental stewardship and responsible work carried out by OCSD.  They directly and actively address the multiple impacts of humans (you and me, every day!) on the environment.  They are tremendous collaborators to scientists.



To date, this work has demonstrated that several marine fish species are exposed to a variety of human-derived chemicals.  Fish have organic contaminants acccumlated in their tissues (muscle and liver have been measured through analytic chemistry techniques), such as polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), several pesticide-related chemicals, and pharmaceutical-related chemicals, among others.  The fish also show significant alterations in important endocrine systems, including reproductive, thyroid and adrenal systems.  This “Endocrine Disruption” is of significant concern, since hormones regulate physiological functions in animals.  Impairment of endocrine systems can affect disease suseptibility, development and growth, metabolism, and reproduction, among others. These studies help us to understand the how wildlife may be impacted in southern California marine environments.  Continuing research is importantly aimed at linking the different contaminants present in the animals to specific physiological effects.

OCSD Trawling_470x260.jpg

Researchers with staff specialists from Orange County Sanitation District (OCSD) Environmental Assessment group working onboard M/V Nerissa.  Fish and other marine wildlife are caught by otter trawling, brought up to the ship's deck, and then sorted by species (as shown in picture).  Two fish species are commonly sought for environmental assessment and research: hornyhead turbot and English sole.

EndoDisr-Contaminants SF Bay fish

Environmental Contaminants and Endocrine Disruption in San Francisco Bay Fish

SF Bay Waterfront.jpg


  • With regional agencies and scientists, this collaborative study focuses on multiple sites located in San Francisco Bay..

  • Pacific staghorn sculpin and Shiner perch were evaluated for chemical contaminant concentrations in their tissues, combined with several endocrine measures to determine relationships among locations, pollutant exposure, and physiology.

  • Fish exhibited significant effects on endocrine systems related to contaminants, posing risk to metabolism, defense, growth and development. 



San Francisco Bay and Skyline

With collaborators at California State University-Long Beach* (CSULB), Moss Landing Marine Laboratories MLML, Northern Arizona University (NAU), and the San Francisco Estuary Institute (SFEI), the PCEC led a large, multi-year study on contaminant effects in wild fish residing in San Francisco Bay.  Several locations within the Bay, from the south bay to north bay, were compared to each other and to sites outside of the Bay (in remote, less impacted areas).  Two indigenous and common fish species were evaluated, the Pacific staghorn sculpin (Leptocottus armatus) and Shiner perch (Cymatogaster aggregata).  In contaminated environments, these fish are exposed to a wide variety of human-derived chemicals.  


Results from this work have demonstated organic contaminants in their tissues such as polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and pesticides.  The same fish show significant effects in important endocrine systems, including the thyroid and
adrenal (cortisol) systems.  This “Endocrine Disruption” is of significant concern since hormones regulate physiological functions in the animals, including defense against disease or parasite infestation, normal development, body growth, metabolism, and reproduction, among others.


These studies have been some of the first of their kind carried out in San Francisco Bay, and continuing research is aimed at linking the different contaminants present in the animals to specific physiological effects.

[*Two groups from CSULB collaborated on this project, the Environmental Endocrinology Lab and the Institute for Integrated Research on Materials, Environment, and Society (IIRMES)]

Are Male Fish in

Santa Monica Bay Undergoing 'Feminization' Due to Environmental Conditions?

Male Fish SMB study
Los Angeles

City of Los Angeles, California, USA




  • Males of the flatfish, Hornyhead turbot, were found by Jesus Reyes to exhibit extraordinarily high blood concentrations of the 'female hormone', 17beta-estradiol.

  • Fish may be exposed to human-derived sex hormones through their environment.

  • Male gonads may be synthesizing the female hormone.


A multi-institution effort was begun in response to the research findings that males from Santa Monica Bay were exhibiting unusually high blood levels of estradiol.  The institutions included CSU-Long Beach Environmental Endocrine Laboratory, City of Los Angeles Environmental Monitoring Division, Orange County Sanitation District Environmental Laboratory, UC-Riverside Aquatic Toxicology Laboratory, Southern California Coastal Water Research Project, LA County Sanitation District, and San Diego Sanitation District. 

Hornyhead turbot, Pleuronichthys verticalis, sampled from Santa Monica Bay appear to have some of the highest estradiol levels of any fish sampled in southern California, with males exhibiting blood estradiol concentrations as high as in reproductive females.  


Continuing work is trying to find out why this is happening.  One possibility is that the fish are accumulating the steroid hormone from their environment, which receives waste water from two of the largest treatment plants in the world.  Human urine contains significant amounts of estradiol, and when millions of humans must urinate daily, a large amount of the hormone may end up in the environment.  


Another possibility is that the males gonads may be “accidentally” (?) making the estradiol, which could possibly result from the conversion of testosterone by certain enzymes that should not be highly expressed in males.  There is some precedent in the
scientific literature that certain chemicals may turn “on” this enzyme pathway –if so, it would be a type of chemically induced “endocrine disruption”.  


See more on this subject on this website

under the RESEARCH page: Endocrine Disruption

Impacts of the Wetlands Restoration of Long Beach's Colorado Lagoon

PCEC collaborates with other community organizations, in this example with Tidal influence and the Friends of the Colorado Lagoon.  This work assesses the potential impacts on native fish species that may be caused by the restoration project.  The effort focuses on the physiological health of shiner perch and California staghorn sculpin, which in part includes measuring endocrine parameters (e.g., thyroid hormone, cortisol) and performing cutting edge proteomics approaches to understand the underlying mechanisms of impacts.

Marine and estuarine wetlands are some of the most unique and yet endangered environments. From development to invasive species to pollution, there are many things that pose a threat to the health of these environments.  Our groups work toward ensuring that at least one urban wetland, the Colorado Lagoon, will be restored and protected.


See this story (link) published in the Long Beach paper, Grunion Gazette

ColoLagoon LB study

PCEC and the San Gabriel River Regional Monitoring Program

Use of New Technologies in Evaluating San Gabriel River Watershed Health

SG River-natural upstream view.jpg

Upstream habitat of the San Gabriel River Watershed.  Downstream, the river travels through urban Los Angeles and Orange Counties and then empties at the ocean between Long Beach and Seal Beach.

The San Gabriel River Watershed includes many different tributaries and waterways that originate in the San Gabriel Mountains, stretching all the way down to the ocean. PCEC in collaboration with the Regional Monitoring Program has undertaken a project to help understand and evaluate the health of the watershed by sampling native insects and determining how the environment may impact the organisms by evaluating their proteome.

A proteome is the profile that results from the natural proteins expressed in an

organism (for more on this technology, click HERE). 

Different environmental impacts will cause different proteins to be expressed in higher or lower concentrations. By evaluating the organisms that make-up the base of the food chain in these environments, we can begin to better understand fundamental impacts on

health of the watershed.  The Regional Monitoring Program has data collected from several previous years that can be used in conjunction with the data collected from this study, to bring together a bigger picture.  This work combines powerful research techniques like proteomics (see more about this HERE) and well established field research approaches to evaluate environmental and biological systems.


View a talk given by Scott Johnson (San Gabriel River Watershed Council,

Los Angeles County Sanitation Districts) and Jesus Reyes of PCEC

A New Tool to Detect Stress

at the Metabolic Level

in Aquatic Insects

click here

snow above Black Sands Beach January 202
Trl to BSandsBch Feb2021.jpg
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