Impact of Disease on Pacific Herring Population Recovery
in Prince William Sound, Alaska (Gary Marty). The major goals of this project
are 1) to determine prevalence and severity of disease in a free
ranging Pacific herring population; and 2) determine how disease
might be limiting population recovery after severe decline in 1993.
This project has recently been expanded to determine, through modifications
of an age-structured assessment model, the contribution of disease
in explaining Pacific herring population fluctuations. This project
builds upon work by the Aquatic Toxicology Program that began in
Prince William Sound with damage assessment studies after the 1989
Exxon Valdez oil spill. As our understanding of disease in the
population increases, we are better able to predict combinations
of life history stages and environmental conditions that would
make a population more susceptible to toxicant exposure. This work
has broad application and is playing a major role in achieving
better understanding of ecotoxicology and the role that environmentally
persistent compounds have in producing toxicity. This research
is funded jointly by Exxon Valdez Oil Spill Trustee Council (1994-2003)
and the National Science Foundation (1999-2002).
Pacific Estuarine Ecosystem Indicators Research (S. Anderson
and R. Higashi). The overall goals of the PEEIR Consortium of over
40 investigators are to develop indicators that environmental managers
can use of: 1) wetland ecosystem integrity and to develop an approach
for synthesizing indicators into technically-defensible assessments
of wetland health; 2) biotic integrity for fish and invertebrate
populations within wetland communities; and 3) toxicant-induced
stress and bioavailability for wetland biota. The focus of PEEIR
as a whole is on wetlands because they are a) delimited, b) ecologically
and commercially important and c) being lost to agricultural, urban
and industrial development. Dr. Higashi is coordinator for the
Bioavailability and Biogeochemistry Component (BBC), which is to
develop the knowledge base and field indicators to help assess
the consequences of changes in pollutant chemical form. Most organic
and inorganic pollutants relentlessly change chemical form due
to biogeochemical processes; the form(s) in turn define both toxicity
and bioavailability. Thus, the BBC will complement the Biological
Responses to Contaminants (BRCC) and Ecosystem Indicators (EIC)
components of the PEEIR. Please see http://www.bml.ucdavis.edu/peeir/ for more information and complete list of investigators.
Development of Ecotoxic Indicators in Fish for Se TMDL
Regulation in the San Francisco Bay-Delta and San Joaquin River
(T.W.-M. Fan,
R.M. Higashi, S. Teh, and P. Green). Splittail fish
are on the "threatened" list
in the San Francisco Bay-Delta Estuary, and this project examines
the biochemical and histological basis of reproductive impacts
of selenium in this and other species. Selenium effects are complex
because the effects are expressed through accumulation of unknown
forms of selenium via the food chain. A culture of splittail
has been established at UC Davis, which enables direct research
on
this wildlife of concern, rather than reliance on model species.
One of the key hypotheses being tested is that of proteinaceous
selenium as a marker of ecotoxic risk.
The Application of Toxicogenomics in Aquatic Toxicology
Testing: A Pilot Study (Teh). Chemically-induced
toxicity is often preceded by or results in alterations in
gene expression patterns and these
changes can be used as a highly sensitive, characteristic,
and informative biomarker for toxicity. Chronic selenium
exposure has
growth and reproductive effects in the adult fish and produces
pathology and teratology in developing embryo at maternal doses
of approximately 15-20 µg.g-1. The principal objective of this
pilot study is the application of toxicogenomics in aquatic
toxicology testing using a sensitive medaka (Oryzias latipes)
fish model.
The aim is to identify specific changes in gene expression
associated with dietary selenium exposure (0.7, 10, 20, 30,
40, and 60 mg/kg
purified casein (PC) diet), in liver and embryos (stages 11,
17, 25, 34 and 36 (hatchling) from exposed adult male and female
medaka.
Dr. Kayoshi Naruse (principal investigator of the Medaka EST
project at University of Tokyo), in his visit to our medaka
culture and
experimental laboratory in June 2002, stated his interest to
collaborate and to supply the expressed sequence tags (ESTs)
to support this
study. Thus far, he has provided us with 103 unique cDNAs (as
ESTs), involved in transcription (24), heat shock (25), phase
I and phase
II metabolism (6 cytochrome P450s), tumor suppression (8),
DNA replication and repair (9), apoptosis (1), vitellogenesis
(2),
and housekeeping (28) have been requested. To ensure that growth
and cellular response to selenium toxicity is also examined,
we have requested additional ESTs from Dr. Naruse, including
fibroblast
growth factor, growth-arrest specific protein, glutathione
transferase, glutathione peroxidase, superoxide dismutase,
and cystolic selenoprotein.
Additionally, ESTs coding for other apoptosis-associated proteins
have also been requested: bcl-2-associated protein x, apoptotic
proteinase-activating factor, Fas receptor, and apoptotic cell
death regulator DAD1. Working with Drs. Buckpitt and Bartosiewicz
(UCD), a cDNA microarray, constructed using these ESTs will
then be used as a target to assess mRNA levels in liver and
embryos
from adult medaka exposed to a full range of selenium. The
success of this pilot study will provide a powerful tool in
identifying
and characterizing changes in gene expression associated with
toxicity or carcinogenicity and could be the foundation for
a fundamentally
new genetic biomarker approach in aquatic toxicology testing.
Simultaneous assessment of multiple toxins will be possible
with this novel
method and could greatly facilitate future aquatic environmental
toxic exposure evaluation.
Chronic Toxicity of Environmental Contaminants in Sacramento
Splittail (Pogonichthys macrolepidotus): A Biomarker Approach.
(Hung, Teh, and Davis). The maintenance of a population of fishes
is heavily influenced by the constantly changing physical and biological
conditions of the ecosystem. Contaminant stress may compromise
the ability of fish to survive natural environmental stressors.
Ultimately, fish populations that are unable to compensate for
additional stress will show reductions in growth, reproductive
capacity, and survival. For a species that has already declined
drastically, survival and reproductive success have profound ecological
significance. When exposed to various stressors such as from contaminants,
the fish may not even survive to carry out the ultimate function
of reproduction. Furthermore, chronic dysfunctions of reproduction
in the surviving fish might ultimately result in decreased fecundity
and fertility, and thus indirectly impacting the population level.
Although water quality deterioration, water diversions, habitat
loss, and degradation (all resulting from human activity) may have
contributed to declines in fish population, there is a high degree
of certainty that splittail population is adversely affected by
exposure to contaminants from commercial, domestic, and agricultural
sources. However, integrated laboratory and field investigations
using biomarker approach to detect and quantify chronic contaminant
responses in splittail are lacking.
The Sacramento splittail (Pogonichthys macrolepidotus), a Federally
listed threatened species, forages on benthic organisms. Splittail
are now largely confined to the Sacramento-San Joaquin Delta, Suisun
Bay, Suisun Marsh, the Napa River, and the Petaluma River except
during spawning migrations in winter and spring (Meng and Moyle,
1995). Juvenile remain in the river system for weeks to a year
before migrating to the delta where they mature at age two. Adult
fish remain in the bay-delta system year round but will migrate
upstream to spawn in fresh water preferably over flooded vegetation.
Unlike other native fish species where laboratory culture is difficult
and expensive, splittail is easily cultured at low cost and will
spawn in captivity providing access to all life stages. Therefore,
we propose to use splittail as a native fish model for chronic
toxicity study.
We will demonstrate the use of biomarkers (biological responses),
in conjunction with ongoing biomonitoring efforts of fish population
by DFG and water, sediment, and tissue contaminant monitoring by
SFEI and USGS, to evaluate the chronic effects of contaminants
on the health of splittail under laboratory and field conditions.
Four functional categories of biological indicators will be measured:
1) indicators of contaminant exposure, 2) indicators of general
condition indices, 3) indicators of organ and reproductive dysfunction,
and 4) indicators of individual-level response. We propose to evaluate
a suite of biomarkers of exposure and effect indicators at several
levels of biological organization to quantitatively: 1) assess
the potential chronic effects of contaminant exposure on various
life stages of splittail under laboratory and field settings, 2)
establish a link between the contaminant exposure and the deleterious
health (growth and reproduction) of individual splittail, and 3)
identify indicators of contaminant exposure that are most cost-effective
for use in future monitoring studies. This will provide valuable
information for future environmental compliance and regulatory
studies and the ecological risk assessment process. These studies
also have practical application as laboratory data linking specific
contaminants with adverse chronic effects (as well as field data
correlating biomarker expression with contaminant exposure) that
could help guide management decisions with respect to determining
acceptable contaminant levels in the environment.
Development of a Chronic Effect Sediment Toxicity Test
Using Enzymatic, Immunologic and Histopathologic Biomarkers.
(Kok-Leng,
Tay, MacDonald, Doe, Teh, Lee ). Sediments are an important ecological
component of the ecosystem. They serve as a sink and as a natural
reservoir for both point and non-point sources of contaminants
introduced into aquatic environments. Sediment contaminants can
be toxic to aquatic biota and can trigger chronic biological responses
in sensitive species causing adverse effects on populations and
communities. Bioaccumulation of contaminants by edible species
can trigger serious human health issues. The objective of this
study is to identify a suite of ecologically valid and cost-effective
biomarker analyses to complement recommended Canadian methods for
measuring toxicity of marine sediments. The focus will be biomarkers
of effect, especially those at higher levels of biological organization
such as histological and enzyme histochemical markers.
