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FY 1998 ABSTRACTS
FY 1998 Summary of Accomplishments
In Fiscal Year 1997, the New Hampshire Water Resource Research
Center (WRRC) continued utilizing the basic grant provided by the
USGS for WRRC administration, and two projects from the previous
year's regional grant proceeded as expected. We received twelve proposals,
three were forwarded to the regional competition, and one was funded.
The Statewide Conference on Water Resources Research Needs was held
in September 1997 and was attended by over 100 people, ranging in
interest and expertise from legislators, consultants, State agencies,
lay people. The final report is pending.
The funded project, "Bacteria and Nutrient Dynamics
in Stormwater Control Systems in New Hampshire", 9/1/97 - 8/31/99,
is being investigated by Dr. Steve Jones of the Jackson Estuarine
Laboratory in Durham, NH. A progress report will be included in the
FY99 Annual Report.
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A SURVEY OF 50 NH LAKES FOR MICROCYSTINS
Principal Investigators: Dr.
James Haney, Miyoshi Ikawa
Descriptors: biotoxins, microcystins, Microcystis, cyanobacteria,
algae, eutrophication, lakes, water quality
Problem and Research Objectives:
Cyanobacteria blooms pose a potential threat to the use of lakes
for both recreation and drinking water supplies. There are increasing
reports of health problems associated with toxic cyanobacteria such
as Microcystis in many parts of the world. Preliminary investigations
in New Hampshire lakes indicated the presence of the hepatotoxin
microcystin in lakes of varying trophic status. The major objective
of this study is to conduct a survey of New Hampshire's lakes to
determine which lakes contain toxic cyanobacteria that produce microcystins
and evaluate whether there is a direct relationship between the presence
of the cyanobacteria toxins and the trophic condition of the lakes.
Principal Findings and Significance:
Results from this study indicate the presence of microcystin toxins
in all of the lakes examined. These findings shift the emphasis from
asking, "which lakes have toxic cyanobacteria?" to "what
controls the level of cyanobacteria toxins in lakes?" By measuring
the MC levels in the lake water as well as the weight-specific concentrations
in the plankton we were able to demonstrate that some lakes have
very small amounts of plankton that are relatively toxic and similarly,
some lakes with large quantities of plankton with low specific toxicity.
Although
eutrophication has been linked with problems of toxic cyanobacteria,
the focus of most previous studies has been on "problem" lakes
that exhibit blooms of cyanobacteria. We have demonstrated that
microcystin toxicity parallels the relationship between nutrients
and phytoplankton biomass (chlorophyll a) and extends from ultra-oligotrophic
to eutrophic lake conditions. This allows for a quantitative forecasting
of the impact of nutrient enrichment on lake toxicity, which could
be important for the management of surface water supplies for drinking
water and recreation.
Because of the emphasis on phosphorus as a
limiting factor for phytoplankton growth in lakes, we initially
tested our microcystin-eutrophication hypothesis using total
phosphorus as the driving nutrient. Surprisingly, nitrogen (total
nitrogen) provided a better predictor of toxin concentration that
phosphorus, suggesting future lake monitoring and research should
also include testing for total nitrogen.
The NH microcystin survey also demonstrated that microcystin toxin
concentrations are correlated with other parameters commonly measured
in lake monitoring programs, such as chlorophyll a, Secchi disk
depth and acid neutralizing capacity. This is a significant finding
in that it indicates the results from lake monitory surveys can be
applied to predict the likelihood of toxicity problems in a lake.
Microcystins
were detected in an extremely broad range of concentrations in
the net phytoplankton and zooplankton of all the lakes tested. Overall,
the zooplankton contained approximately 20% of the phytoplankton
microcystin content, indicating considerable amount of this toxin
are passing into the lake food web and possibly being bioaccumulated
by other lake biota such as fish and benthic consumers. Some
of the study lakes had high levels of microcystins in the zooplankton,
compared to other lakes with comparable nutrient levels, raising
questions concerning the loll of the composition of the lake food
web in the transfer of toxins. The strong positive correlation
between zooplankton MC and the % Daphnia in the lakes suggests the
species composition of the zooplankton grazers may influence the
transfer of mycrocystins. Likewise, it is likely that the degree
of fish planktivory in the lake may indirectly impact the efficiency
of movement of MC from the phytoplankton to the zooplankton grazer
community. Clearly, investigations of microcystin transfer through
lake food webs are needed to better understand these processes.
Our data support the model that, in general, nutrients promote the
development of microcystin toxicity in lakes. The utility of these
models, however, is limited by the high lake-to-lake variability.
Other factors must clearly be included in future models to be useful
for forecasting the effects of nutrient enrichment on lake toxicity.
We have identified lake mean depth as an important variable, along
with factors such as the buffering capacity or ANC of the water.
Long-term studies should be undertaken on a subset of lakes to
incorporate the influence of light and temperature. Such models would
have greater predictive power for specific lakes and also permit
long-range forecasting of the effects of global climate change on
lake toxicity.
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BACTERIAL AND
NUTRIENT DYNAMICS IN STORMWATER CONTROL SYSTEMS IN NEW HAMPSHIRE
Principal Investigator: Dr.
Stephen H. Jones
Descriptors: Bacteria, nutrients, storm water management, contaminant transport,
public health, water quality standards
Problem and Research Objectives:
Runoff from impervious surfaces in urban areas contains significant
amounts of hazardous contaminants, including microbial pathogens/indicators,
heavy metals, and toxic organic compounds like oils and hydrocarbons.
Such contaminants pose threats to humans directly during recreation
uses of surface waters and seafood consumption, and aquatic life
through chronic and acute exposure to toxic concentrations. Water
quality in New Hampshire's coastal areas is negatively affected by
stormwater, especially the bacterial contamination that prohibits
shellfish harvesting. However, the sources of contaminants are unknown,
as are the fate and transport of contaminants to surface waters.
Suspected sources are inappropriately cross-connected sanitary sewage
lines, leaking lines, and non-human sources of non-enteric pathogens.
In many studies, bacterial indicator contamination during dry periods
and in runoff where no human sources of contaminants can be identified
has been attributed to animal sources. In numerous recent studies
in New Hampshire, evidence for animal sources has not been apparent
and elevated concentrations of indicator bacteria following storms
at some locations appeared to be independent of any identifiable
sources. The hypothesis for this study is that low levels of bacteria
giving positive indicator tests can multiply in the environment under
favorable (warm, moist, plentiful nutrients) conditions in stormwater
control systems during dry periods, and give misleading indications
of fecal contamination in storm effluent water.
The study sites include two wet ponds and two vegetated
swales in coastal New Hampshire that have been the subject of a previous
study. Sampling will occur at all four sites around eight storms
of >0.5"/24
h during the study period. In addition to storm event sampling, dry
weather sampling will be conducted between storms (nine times) to
provide base flow information on contaminants and conditions within
the study areas. All samples will be analyzed for bacterial indicators
used for classifying surface waters in NH (fecal coliforms, Escherichia
coli and enterococci). In addition, all samples will be analyzed
for dissolved nitrogen (nitrate/nitrite, ammonium, dissolved organic
nitrogen), dissolved organic carbon, total phosphorus and suspended
solids. At sites with elevated microbial indicator levels, samples
collected during at least one event per season will be analyzed for
some common bacterial pathogens, including Pseudomonas aeruginosa,
Klebsiella sp., Salmonella sp. and Escherichia coli. The most direct
benefit of this project will be an increased understanding of the
nature of one of the most important existing sources of bacterial
contaminants to surface waters. This study will help to determine
if permanent stormwater control systems are effective at removing
bacteria and nutrients, or are actually sources. The data would also
provide information needed for development of new technologies for
treating stormwater, if necessary. Even though bacterial contamination
results in the closure of shellfish beds and restricts recreational
uses of surface waters, the actual public health threat of contamination
implied from elevated concentrations of indicator bacteria is unclear.
This study will provide results on the presence of bacterial pathogens
in addition to indicator bacteria to shed light on the public health
question.
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