Proposal: Tahoe Science Program Round 12 Request for Proposals
I. Title Page
Project Title:
Subtheme addressed by this
proposal
Principal Investigator and
Receiving Institution
Co-Principal Investigator
Co-Principal Investigator
Agency Collaborator
Agency Collaborator
Agency Collaborator
Agency Collaborator
Grants Contact Person
Funding requested:
Total cost share (value of
financial and in-kind
contributions):
Understanding the decline of deepwater sensitive species in Lake
Tahoe: What is responsible, eutrophication or species invasions?
2c: Increasing our understanding of special status species and
communities
Dr. Sudeep Chandra
Board of Regents, NSHE, obo University of Nevada- Reno
Department of Natural Resources and Environmental Science
1000 Valley Road/MS 186, Reno, Nevada 89512
Phone: 775-784-6221, Fax: 775-784-4530
Email: sudeep@cabnr.unr.edu
Dr. John Reuter
University of California- Davis
UC Davis Tahoe Environmental Research Center, Davis, CA 95617
Phone: 530-304-1473, Fax: 530-754-9364
Email: jereuter@ucdavis.edu
Dr. Eliska Rejmankova
University of California- Davis
Dept of Environmental Science and Policy
University of California, Davis, Davis, CA 95617
Phone: 530-304-1473, Fax: 530-754-9364
Email: erejmankova@ucdavis.edu
Shane Romsos and Patrick Stone
Tahoe Regional Planning Agency
PO Box 5310, Stateline, NV 89449
Phone: 775-589-5201, 775-589-5213, Fax: 775-588-4527
Email: sromsos@trpa.org, pstone@trpa.org
Kevin Thomas
California Department of Fish and Game
North Central Region
1701 Nimbus Road, Rancho Cordova, CA 95670
Phone: 916-358-2845, Fax: 916-358-2912
Email: kthomas@dfg.ca.gov
Patrick Wright
California Tahoe Conservancy
1061 Third Street , South Lake Tahoe, CA 96150
Phone: 530-543-6002, Fax: 530-542-5591
Email: pwright@tahoe.ca.gov
Elizabeth Harrison
Nevada Division of State Lands
901 S Stewart Street, Suite 5003, Carson City, NV 89701
Phone: 775- 684-2736, Fax: 775-684-2721
Email: eharrison@lands.nv.gov
Carla Beier
University of Nevada- Reno
Office of Sponsored Projects/MS 325, Reno, NV 89557
Phone: 775-784-6754, Fax: 775-784-6680
Email: ospadmin@unr.edu
$ 281,623
$0
Proposal: Tahoe Science Program Round 12 Request for Proposals
II. Proposal Narrative
a. Project abstract
A comparison of historical and contemporary benthic surveys showed a large decline in bottom
invertebrate and plant occurrence in the deepwater environment of Lake Tahoe (Caires et al. 2010). The
decline in plants may be directly related to reductions in water clarity over the past 4 decades, while
reductions in the invertebrate community may be related to plant declines and invasive species
introductions. Two of Lake Tahoe’s unique bottom species (a blind amphipod and a deep-water
stonefly), found nowhere else in the world, are at high risk given their significant reduction since the
1960s. Currently, the deepwater benthic environment in Lake Tahoe is not being monitored and is not
well understood. We will examine the spatial distribution of these deepwater special status plant and
invertebrate communities and, in doing so, gather information about their biology and ecology.
Specifically, we will study the life cycles of special status plants and invertebrates and feeding strategies
of endemic invertebrates. We will also measure native plant photosynthetic rates at varying light
conditions and relate observed plant responses to long term subsurface irradiance data in order to
understand the depths at which light has been limiting for deepwater plants over the last four decades and
how this has affected changes in their vertical distribution. The influence of future clarity improvement
(as part of the TMDL strategy) on the redistribution of this special deepwater plant community will be
evaluated using a model to be developed for this purpose. Non-native invertebrate effects on special
status communities will also be analyzed in the laboratory. We hope to determine mechanisms that have
contributed to the decline of these unique deepwater plant and invertebrate communities and develop
appropriate restoration strategies. A monitoring plan will be developed to allow managers to track special
status community response to restoration strategies, such as changes in light penetration and/or reductions
in non-native species. Monitoring of relatively long-lived organisms such as aquatic plants and
invertebrates provides an important biological indicator of the overall health of the system, one that has
received little attention in Lake Tahoe.
b. Justification statement
Research conducted by our team in 2008-2010 suggests that benthic plant and invertebrate distribution
and density have been substantially reduced in Lake Tahoe since the 1960s. Our proposal explicitly
addresses subtheme 2c, “Increasing our understanding of special status species and communities,” by
determining mechanisms leading to the decline of the endemic Tahoe stonefly, blind amphipod, and
associated deepwater plant communities. These special status communities can be used to assess
alterations and trends that have occurred in pelagic (through coupling to the bottom) and benthic
environments. We will study these communities and their role in ecological processes through field
collections and laboratory experiments, along with a model to help us understand how these communities
have responded to decreased clarity in the lake. Based on our findings, we will make recommendations
for actions that could improve habitat and potentially restore these special status communities. This
project is highly relevant to current efforts in the Tahoe Basin to develop a complete set of environmental
indicators that evaluate lake condition and compliment the open water indicators currently employed to
quantify changes to the lake.
c. Concise background and problem statement
Deepwater special status communities in Lake Tahoe.
Historical invertebrate surveys from the benthic environment in Lake Tahoe have been extremely limited;
however, they do reveal the existence of a variety of unique, endemic benthic invertebrate taxa, mostly
found in deep water (Frantz and Cordone 1966, 1996). Lake Tahoe’s endemic benthic faunal assemblage
includes two species of blind amphipod (Stygobromus spp.), typically found in subterranean
environments, and the Tahoe stonefly (Capnia lacustra) that is one of only two taxa in the world known
to live its entire life-cycle underwater (Baumann 1984). Lake Tahoe also has a unique assemblage of
deepwater plant beds, including several species of stoneworts, liverworts, and mosses, concentrated
historically at depths around 100 meters (Frantz and Cordone 1967). Recently we synthesized historical
Proposal: Tahoe Science Program Round 12 Request for Proposals
information and compared it to contemporary surveys of benthic invertebrate communities conducted in
2008-09. Our findings indicate that there has been a severe (75%) decline in lakewide, weighted benthic
invertebrate densities since the 1960s, with blind amphipods and Tahoe stoneflies showing the greatest
declines at >99% and 94%, respectively (Caires et al. 2010; Figures 1a-1c). A comparison of
contemporary and historical benthic samples also shows a reduction in the occurrence of aquatic plants in
benthic samples, and a shift of plants to shallower waters (Figure 1d).
Despite this severe decline in deepwater plant and invertebrate abundance in Lake Tahoe over the past 50
years, the biology, ecology and current distribution of these organisms is not well understood. Benthic
invertebrate densities were highest in plant-dominated samples in the 1960s collections (Figure 2),
suggesting that deepwater plant communities are important to native invertebrate assemblages. The
association between the endemic Tahoe stonefly and deepwater plants in Lake Tahoe has been described
(Jewett 1965), and the Tahoe stonefly was located in plant beds in the South Lake Tahoe area in recent
surveys. Conversely, there is no clear association between aquatic plants and blind amphipods in Lake
Tahoe. In fact, in the 1960s, blind amphipods were most abundant in areas that were deeper than the
depth limits of most aquatic plants in the lake (Frantz and Cordone 1996). Although the dietary
preferences and requirements of blind amphipod species in Lake Tahoe have not been studied, many other
amphipod taxa rely on organic matter and associated bacterial assemblages for food (Covich and Thorp
2001). It is possible that blind amphipods in Lake Tahoe are dependent on detritus and associated
bacteria largely derived from these deepwater plant beds. Information about the life history and feeding
habits of the Tahoe stonefly and the blind amphipod could provide insight into associations between these
special status invertebrates and their preferred habitat.
Our surveys in 2008-09 revealed two locations in which Tahoe stoneflies were located: McKinney Bay
and South Lake Tahoe. Deepwater plant beds were also located in South Lake Tahoe and blind
amphipods were found in McKinney Bay. Dispersed sampling in these “hotspot” areas where special
status communities have been found previously will provide information on their finer scale spatial
distribution in these areas. Once target areas are identified, focused, frequent sampling will provide
insight into the life histories of special status taxa, as determined by seasonal developmental state. Stable
isotope analysis will allow for determination of feeding habits of endemic invertebrates. Carbon and
nitrogen stable isotopes can show energy flow in food webs, where δ15N signatures indicate the trophic
position of a target consumer and δ13C signatures can be used to discriminate between benthic and pelagic
sources of energy in a consumer (Vander Zanden et al. 2003). Determination of feeding position and
food sources will help link endemic invertebrates to their preferred habitat and may provide some insight
as to the source of their observed declines.
Alterations to the clarity and benthic ecology of Lake Tahoe in the last 50 years.
Increased nutrient and sediment inputs to Lake Tahoe since the 1960s have caused primary productivity
to steadily increase while clarity has steadily decreased (Goldman 1988, Jassby et al. 2003, TERC 2011;
Figure 3). Efforts to improve lake clarity and water quality through environmental thresholds established
by the Tahoe Regional Planning Agency (TRPA) and the development of a Total Maximum Daily Load
(TMDL) by the Lahontan Water Board and Nevada DEP are intended to help reverse these trends.
Measurements of physical, chemical, and biological parameters in the lake, such as transparency, nutrient
content, and phytoplankton primary productivity/chlorophyll have been useful as indicators of changes in
Lake Tahoe’s water quality (Goldman 1988; Jassby et al. 1994, 2003; Swift et al. 2006). Current
monitoring efforts provide snapshots of the open water lake condition. Chandra et al. (2005) suggest that
observed changes to the open-water of Lake Tahoe are directly impacting bottom processes. Thus,
developing a method to assess changes at the bottom of the lake will integrate open-water monitoring
with longer-term change to benthic habitats.
Benthic plant distribution is regulated by underwater light availability (e.g. Schwarz et al. 1996, 1999,
Proposal: Tahoe Science Program Round 12 Request for Proposals
2000), and increases in open water primary production and sediment particles in lakes can result in
shading of benthic environments (Sand-Jensen and Borum 1991). The predictable growth responses of
aquatic plants to changes in subsurface light availability suggest their potential as direct responders to
water clarity changes. Decreased clarity in Lake Tahoe has decreased subsurface irradiance, likely
contributing to the shift of deepwater plant communities to shallower water. Deepwater plants in Lake
Tahoe also have shallow water depth limits due to growth limitations caused by wave action and
unsuitable substrate (Frantz and Cordone 1967). Thus, there has been a narrowing depth band of suitable
habitat for deepwater plants in Lake Tahoe. Despite apparent declines in overall density, deepwater
plants were located in recent benthic samples, suggesting that an improvement in water clarity could
allow plant communities to reestablish at deeper depths. In other lakes, benthic plants have readily
responded to changes in lake clarity (Zhu et al. 2006, Schwarz et al. 1999). For example, in a large
oligotrophic New Zealand lake, Chara responded negatively to a decline in lake clarity, but recovered
within two years when clarity improved (Schwarz et al. 1999).
Photosynthesis-irradiance (P-I) curves describe plant responses to changing light regimes, and they
indicate light-compensation points below which there is insufficient light to compensate for respiratory
losses. The development of P-I curves for the most common deepwater plant taxa in Lake Tahoe would
provide an indication of the growth limitations of special status plant communities. This, combined with
subsurface irradiance data that has been collected in Lake Tahoe since the late 1960s, could indicate the
depth limit of aquatic plant growth over the past 40+ years. Similarly, the vertical extent plant growth
and abundance could be projected into the future based on efforts to improve clarity.
It is possible that non-native species have also negatively affected special status communities in Lake
Tahoe over the past four decades. In 1963-65, shortly after the 1962-63 benthic invertebrate survey,
333,000 mysid shrimp (Mysis relicta) were introduced to Lake Tahoe as a food source for lake trout
(Salvelinus namaycush) (Linn and Frantz 1965, Frantz and Cordone 1996). The mysid shrimp established
a large population (approximately 300 per m2) by 1971 and subsequently caused the disappearance of two
cladoceran species (Richards et al. 1975, Goldman et al. 1979, Threlkeld 1981). Mysid shrimp in Lake
Tahoe feed at night in the water column and migrate to the bottom of the lake during the day to avoid fish
predation, for a total daily vertical migration of up to 1000 m (Rybock 1978). These omnivorous
crustaceans consume a variety of benthic and pelagic food items, including zooplankton, amphipods, and
even small fish larvae (Parker 1980, Sealer and Binowski 1988, Johannsson et al. 2001, Wilhelm et al.
2002, Bailey et al. 2006). Mysid shrimp appear to be extremely abundant on sediment surfaces during the
day in South Lake Tahoe, as seen in video surveys taken by a remotely operated vehicle in 1990 (see
Beauchamp et al. 1992). It is possible that mysid shrimp have taken advantage of endemic benthic
invertebrates in Lake Tahoe as a food source, especially exposed blind amphipods in profundal areas too
deep for plant growth. Another omnivorous, non-native invertebrate, the signal crayfish (Pacifastacus
leniusculus) may also be contributing to the decline of native plant and invertebrate species. Although
present in the lake since 1895, crayfish numbers have nearly doubled since the 1960s (Chandra 2011;
Figure 4). Adult crayfish in Lake Tahoe target benthic periphyton and plants for food, while juvenile
crayfish consume mainly small benthic macroinvertebrates (Flint 1975). Mysid shrimp in Lake Tahoe
have not been surveyed recently, and their benthic sources of food have not been investigated. A better
understanding of mysid and crayfish benthic food preferences would allow for determination of their
potential to impact special status communities in Lake Tahoe.
In most other oligotrophic lakes, eutrophication has been known to increase benthic invertebrate densities
through increased pelagic primary production and subsequent fallout to the benthos (e.g., Robertson and
Alley 1966, Clarke et al. 1997, Nalepa et al. 2000). Comparisons of contemporary and historical
collections suggest that the opposite has occurred in Lake Tahoe. Increased eutrophication may be
causing increased shading to the benthos and associated declines in benthic plant abundance. It is
possible that this decline in preferred native habitat for endemic invertebrates, along with an increase in
Proposal: Tahoe Science Program Round 12 Request for Proposals
numbers of non-native invertebrate taxa has resulted in the dramatic endemic invertebrate declines
recently observed (Figure 5). The field collections and lab experiments proposed herein will allow for a
greater understanding of Lake Tahoe’s unique special status communities and the mechanisms
contributing to their declines.
d. Goals, objectives, and hypotheses to be tested
The goals of this proposal are: 1) increase our understanding of the biology and ecology of deepwater
special status plant and invertebrate communities, 2) determine mechanisms (e.g. decreased water clarity
and the introduction of non-native species) that have contributed to declines in these communities over
the past 40+ years, and 3) to create a restoration and monitoring plan based on determined mechanisms.
Specific objectives and related hypotheses include:
Objective 1. Increase our understanding of special status aquatic plant (stoneworts, liverworts, and
mosses) and invertebrate (Tahoe stonefly and blind amphipod) communities in deepwater “hotspot” areas
of Lake Tahoe and relate the distribution of these communities to depth, subsurface irradiance, substrate
type, and availability of organic matter in sediments.
Hypothesis 1: The spatial extent of deepwater plant communities in Lake Tahoe is influenced by
depth, substrate, and the amount of light reaching benthic habitats. Special status invertebrate
distribution is determined by depth, substrate type (including plant presence or absence), and organic
matter availability in sediments.
Objective 2. Increase our understanding of the biology and ecology of special status deepwater plants and
invertebrates through seasonal tracking of populations, developmental state, and diet using stable
isotopes.
Hypothesis 2. Deepwater stoneworts, mosses, and liverworts will be present throughout the year. The
Tahoe stonefly and blind amphipod will have relatively long (≥1 year) life cycles, based on the deep,
coldwater conditions of the targeted benthic habitats. Endemic invertebrates will be reliant on
organic matter from pelagic sources when benthic sources of organic matter are not readily available.
Objective 3. Develop a P-I curve for commonly encountered deepwater plants in Lake Tahoe and link
the curve to historical light data to determine how plant communities have responded to changes in clarity
and how they may respond to future changes in water clarity.
Hypothesis 3. Plant distribution is restricted to a limited depth interval in Lake Tahoe that
corresponds with subsurface irradiance levels sufficient for growth. Change in plant distribution over
time is linked to the amount of light reaching benthic habitats and thus can be projected into the
future according to load reduction scenarios in the Tahoe TMDL.
Objective 4. Determine if non-native invertebrate species are affecting special status communities.
Hypothesis 4. Introduced mysid shrimp and signal crayfish are both opportunistic crustacean
omnivores in Lake Tahoe. The introduction and increase in abundance of these species in Lake
Tahoe have affected deepwater special status communities through the alteration of habitat and direct
predation.
Objective 5. Identify a strategy to conserve and restore habitat for deepwater special status plant and
invertebrate communities and develop a monitoring plan to evaluate community response to conservation
and restoration strategies.
Proposal: Tahoe Science Program Round 12 Request for Proposals
Hypothesis 5. Improvements in water clarity and declines in non-native invertebrates will help
restore special status communities in Lake Tahoe.
e. Approach, methodology and location of research
Objective 1. Deepwater plant and invertebrate communities will be sampled at two deepwater “hotspot”
areas in Lake Tahoe. “Hotspot” areas are defined here as areas where endemic communities were located
in recent surveys (McKinney Bay and South Lake Tahoe; Figure 6). Although deepwater plants and
associated endemic stoneflies should be relatively easy to encounter in the targeted area in South Lake
Tahoe, blind amphipods will likely be harder to find, given their poor representation in samples collected
in 2008-09. At least five replicate samples will be collected with a Ponar grab at each depth for each
location. Sampling effort will increase as the difficulty of encountering an organism increases. Initial
surveys will occur in July and September to determine the spatial occurrence of benthic plants and
invertebrates. If deepwater plants are not encountered with a Ponar grab, short benthic trawls will be
conducted at discreet depths. At each location, measurements of subsurface irradiance will be taken with
a Li-Cor underwater PAR sensor and Secchi depth will be recorded. Once plant and endemic distribution
is determined for each location, areas with the highest densities of these taxa will be targeted for temporal
analysis, as described in objective 2.
Upon collection of a sample, live plant material will be removed and placed on ice for identification and
morphological analysis in the laboratory. In the laboratory, plants will be identified, their general
condition recorded, and selected characteristics such as length and photosynthetically active area will be
measured. If justified by preliminary trials, we will also measure chlorophyll a and b and carotenoid
concentrations (pigment per unit of plant biomass) because the absolute values as well their ratios are
usually related to the light response of photosynthesis (Marschal and Proctor 2004). Plants will be dried
to a constant biomass at 70° C and weighed. Once plants are removed, samples will be sieved through a
500 µm mesh bucket sieve. Material retained in the sieve will be picked for live invertebrates and
invertebrates will be placed in 70% ethanol for laboratory analysis. All sediment will be kept, dried at
70° C to a constant biomass, sieved, and weighed to determine the relative percentage of each sediment
category (silt, sand, gravel, and cobble) according to Wentworth (1922). Sediment will be combusted at
550° C for 2 h to determine the ash-free dry mass (AFDM) of organic material in each sample.
Objective 2. Samples will be collected six times throughout the year (March, May, July, September,
November, and January) from target locations where special status plant and invertebrates are found in
initial surveys (objective 1). When encountered, endemic invertebrates will be measured (body length
and head capsule width) and weighed in an attempt to determine seasonal size distribution for life history
determinations. Endemic invertebrates will also be analyzed for stable isotopes to determine feeding
habits (pelagic vs. benthic sources and trophic position). Plants will be identified, morphologically
examined, dried and weighed as described in objective 1 to determine seasonal distribution and life
history characteristics.
Objective 3. Deepwater plants will be collected from areas where they are encountered during late
summer to determine rates of photosynthesis rates under differing light conditions. Upon collection, a
standard fresh weight of plant will be incubated in a BOD bottle filled with lake water for approximately
two hours. For the duration of the experiment, bottles will be kept in a water bath equilibrated to the
temperature of the bottom environment from which the plants were collected. Neutral density filters will
be used to shade bottles, thus exposing plants to different irradiance levels corresponding to the measured
light intensity along a vertical depth profile in Lake Tahoe. The triplicated treatments will include dark
bottles to measure plant respiration and light bottles without plants as controls. Oxygen measurements
will be taken with an oxygen electrode in the bottles before and after incubation to determine
photosynthesis-irradiance (P-I) curves for the most commonly encountered deepwater plant taxa in Lake
Tahoe (sensu Menendez and Sanchez 1998, Goldsborough and Kemp 1988). The relationship between
Proposal: Tahoe Science Program Round 12 Request for Proposals
the P-I curve obtained and long-term subsurface light data will allow for modeling of plant community
responses to changing light conditions over time (past and future). In particular, we will use the predicted
changes in lake transparency modeled from various load reduction scenarios in the Lake Tahoe TMDL to
evaluate the impact on deepwater benthic plants.
Objective 4. Non-native opossum shrimp (Mysis relicta) and signal crayfish (Pacifastacus leniusculus)
will be collected 2-3 times per year in McKinney Bay and South Lake Tahoe. Opossum shrimp will be
collected by dragging a large-diameter zooplankton net along the bottom of the lakeduring the day and
placing collected individuals immediately formalin for gut content analysis. Crayfish will be collected
with minnow traps and preserved in formalin immediately for gut content analysis. Additional opossum
shrimp and crayfish will be collected and acclimated to laboratory conditions for use in laboratory
experiments. In the laboratory, experiments testing opossum shrimp and crayfish predation on amphipods
and stoneflies will be conducted. In each experiment, surrogates of endemic invertebrates will be used
due to the difficulty and impact of collecting large quantities of endemic invertebrates. Common
amphipods and stoneflies from other systems will be used to represent endemic Tahoe invertebrates. The
size of surrogates will reflect juvenile and adult forms of each endemic taxon and caution will be taken in
interpreting results given that surrogate prey items may differ slightly from actual special status species.
One opossum shrimp will be placed in tanks with five potential prey items of the same taxon and
experimental tanks will be checked at 1, 3, and 6 hours to determine prey consumption. Experimental
treatments will be: no substrate, silt substrate, gravel substrate, and silt/plant substrate. Predation by
crayfish on amphipods, stoneflies, and plants will be conducted using the same treatment types and
laboratory conditions. Light and temperature conditions in the laboratory will be matched as closely as
possible to field conditions.
Objective 5. Information collected from field and laboratory analyses in objectives 1-4 will allow for
determination of conservation and restoration strategies for deepwater special status communities and
their habitat in Lake Tahoe. Mechanisms determined to have been most detrimental to deepwater special
status communities in Lake Tahoe will be identified as target stressors that should be managed, if
possible. A monitoring plan will be developed to allow managers to determine how deepwater special
status communities might respond to restoration measures. The monitoring plan will include details about
tracking these communities and their responses to changes in the benthic environment over time.
f. Relationship of the research to previous and current relevant research, monitoring, and/or
environmental improvement efforts
Of critical importance is the direct connection between this proposed research and current efforts to
develop and refine an environmental indicators program and a monitoring and evaluation program for
Lake Tahoe. The Tahoe Regional Planning Agency and collaborating partners have had numerous
meetings in the last seven years to (1) determine environmental condition, (2) assess response to
restoration efforts, (3) monitor status and trends, and (4) establish scientifically-based targets for
indicators of choice. The proposed research will contribute significantly to these emerging efforts by
focusing on an area that has not been previously considered in Lake Tahoe. Previous funding (20092010) by the Tahoe Regional Planning Agency recognized our lack of understanding of the benthic
environment and the importance of baseline community characterization given recent invasive species
discoveries and eutrophication to the lake. This was the first major funding for benthic biodiversity
studies since the 1960s. As previously noted, our scientific team has discovered dramatic changes to
benthic assemblages at the lake bottom (see Figure 1), suggesting that we should pursue additional
information about this deepwater environment, particularly where declines have occurred. We hope to
refine our understanding of benthic processes to develop indicators that are reliable and sensitive to the
Proposal: Tahoe Science Program Round 12 Request for Proposals
changing conditions in Lake Tahoe. Other large lake ecosystems have undergone much greater
alterations due to eutrophication (oligotrophic to eutrophic) and have documented subsequent changes to
benthic plant and invertebrate communities. Surprisingly, Lake Tahoe has only undergone progressive
eutrophication with a slight change in trophic status; thus restoration of habitat for deepwater special
status communities is possible.
g. Strategy for engaging with managers and obtaining permits
We will engage managers by presenting quarterly updates to the funding agency and an annual
presentation to agencies managing water quality thresholds within the basin (Tahoe Regional Planning
Agency, Lahontan Water Quality Control Board, Nevada Division of Environmental Protection,
California Department of Fish and Game, and the Nevada Department of Wildlife). We will also present
at technical meetings, the Tahoe Science Symposium, and to the Science Management Integration team or
other agency sponsored meetings as requested. We did not have to apply for permits for our previous
whole lake survey project funded by the Tahoe Regional Planning Agency; thus, to our knowledge, we
are not required to obtain permits. If this changes, we will comply with permitting needs and request
additional funding to process these permits. Finally, we will create information fact sheets that can be
placed on websites or handed out at the annual Tahoe summit in the summer time to inform policy makers
and the public about the ecology and status of endemic species and their habitat.
h. Description of deliverables/products and plan for how data and products will be reviewed and
made available to end users
A primary product of this project will be the determination of the mechanisms contributing to the decline
of deepwater special status communities and development of recommendations to conserve and restore
habitat for these communities. Once these mechanisms are determined, we will provide a monitoring
plan that will allow for evaluation of special status community response to changes in variables associated
with the declines (e.g. water clarity, density of invasive species). In the monitoring plan, we will provide
specifics for future monitoring, such as optimal temporal and spatial targets for sampling and appropriate
methodologies. Additionally, we will provide information related to the biology, status, and distribution
of native deepwater aquatic plants and endemic invertebrates. A preliminary report (end of first year),
and a final report (end of project) will be prepared. Throughout the project, we will be working in close
cooperation with Shane Romsos, Acting Branch Chief of the Tahoe Regional Planning Agency, who has
been working with other agencies to develop quantifiable indicators to address changes in the Lake Tahoe
Basin. In order to facilitate the transfer of information to audiences beyond the Tahoe basin, we will
present at annual scientific meetings (American Society of Limnology and Oceanography or the North
American Benthological Society), and make public presentations of data as requested.
Proposal: Tahoe Science Program Round 12 Request for Proposals
III. Schedule of major milestones/deliverables
Project Dates: June 1, 2012 – May 31 2014
Milestone/Deliverables
Start Date End Date
Prepare progress reports
June 2012 April 2014
Description
Submit brief progress report to Tahoe Science
Program coordinator by the 1st of July,
October, January, and April
Prepare field equipment; Initiate field
collections for dispersed deepwater benthic
sampling
Initiate field collections for focused seasonal
sampling and determination of life history
characteristics
Process and identify plants and invertebrates
from field collections. Process stable isotope
samples
Run P-I curve for common Lake Tahoe plants
and process data
Objective 1
Field Collections
June 2012
October
2012
Objective 2
Field Collections
October
2012
October
2013
September
2012
December
2013
Objective 3
July 2013
October
2013
Objective 4
October
2013
Objective 5
January
2014
January Run laboratory experiments with non-native
2014 invertebrates and process laboratory
experiment data
March Prepare restoration strategy recommendations
2014 and monitoring plan
1st annual
accomplishment report
September
2013
September Prepare annual summary of accomplishments
2013
Final presentation to
basin managers
April 2014
April 2014 Final presentation to basin managers seeking
oral feedback for the final report
Final report
May 2014
May 2014 Final submission of our final report including
an Executive Summary
Objectives 1-2
Proposal: Tahoe Science Program Round 12 Request for Proposals
IV. Literature cited/References
Abrahamson, S.A.A., and C.R. Goldman. 1970. Distribution, density, and production of the crayfish
Pacifastacus leniusculus Dana in Lake Tahoe, California-Nevada. Oikos 21:83-91.
Bailey, R.J.E., J.T.A. Dick, R.W. Elwood, and C. MacNeil. 2006. Predatory interactions between the
invasive amphipod Gammarus tigrinus and the native opossum shrimp Mysis relicta. Journal of the
North American Benthological Society 25:393-405.
Baumann, R.W. 1984. Review: aquatic insects. Ecology 67:589-590.
Beauchamp, D.A., B.C. Allen, R.C. Richards, W.A. Wurtsbaugh, and C.R. Goldman. 1992. Lake trout
spawning in Lake Tahoe: egg incubation in deepwater macrophyte beds. North American Journal of
Fisheries Management 12:442-449.
Caires, A., S. Chandra, M. Wittmann, and G. Schladow. 2010. Long-term change in benthic invertebrate
assemblages in Lake Tahoe, California/Nevada. 5th biennial meeting abstracts-Lake Tahoe Basin
Science Conference, Incline Village, Nevada.
Chandra, S. 2011. Signal crayfish (Pacifastacus leniusculus) in Lake Tahoe: history, ecology, and
potential management. Report to Nevada Board of Wildlife Commissioners. University of Nevada,
Reno.
Chandra, S., M.J. Vander Zanden, A.C. Heyvaert, B.C. Richards, B.C. Allen, and C.R. Goldman. 2005.
The effects of cultural eutrophication on the coupling between pelagic primary producers and benthic
consumers. Limnology and Oceanography 50:1368-1376.
Clarke, K.D., R. Knoechel, and P.M. Ryan. 1997. Influence of trophic role and life-cycle duration on
timing and magnitude of benthic macroinvertebrate response to whole-lake enrichment. Canadian
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Covich, A.P., and J.H. Thorp. 2001. Introduction to the subphylum Crustacea. Pages 777-809 in Ecology
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Tahoe, 1961-1964. Biological society of Nevada occasional papers no. 8. 12 pp.
Frantz, T.C., and A.J. Cordone. 1967. Observations on deepwater plants in Lake Tahoe, California and
Nevada. Ecology 48:709-714.
Frantz, T.C., and A.J. Cordone. 1996. Observations on the macrobenthos of Lake Tahoe, CaliforniaNevada. California Fish and Game 82:1-41.
Goldman, C.R. 1988. Primary productivity, nutrients, and transparency during the early onset of
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24:289-297.
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survival in turbid tidal waters. Ecology 69: 1775-1786.
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nitrogen and phosphorus in Lake Tahoe (California-Nevada). Water Resources Research 30:22072216.
Jassby, A.D., J.E. Reuter, and C.R. Goldman. 2003. Determining long-term water quality in the presence
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Dermott, and R.H. Hesslein. 2001. Diet of Mysis relicta in Lake Ontario as revealed by stable isotope
Proposal: Tahoe Science Program Round 12 Request for Proposals
and gut content analysis. Canadian Journal of Fisheries and Aquatic Sciences 58:1975-1986.
Linn, J.D., and T.C. Frantz. 1965. Introduction of the opossum shrimp (Mysis relicta Loven) into
California and Nevada. California Fish and Game 51:48-51.
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Proposal: Tahoe Science Program Round 12 Request for Proposals
V. Figures
Figure 1. A comparison of historical (1962-63) and contemporary (2008-09) data from benthic collections
in Lake Tahoe. The comparisons show: a) lakewide mean±SE total invertebrate density, b) blind
amphipod densities by depth, c) Tahoe stonefly densities by depth, and d) benthic plant occurrence at
defined depth intervals.
Proposal: Tahoe Science Program Round 12 Request for Proposals
Figure 2. Mean±SE invertebrate density for each sediment category (dominant substrate) in benthic
collections from the 1960s.
Figure 3. Secchi depths recorded from 1968-2011 by UC Davis, showing the steady decline in water
clarity since the late 1960s. Figure taken from TERC (2011).
Proposal: Tahoe Science Program Round 12 Request for Proposals
Crayfish (mean density/trap)
40
35
30
25
20
15
10
5
0
1967
1974
2008
Year
Figure 4. Average lakewide density (total crayfish per trap) in Lake Tahoe for three time periods since
1967. Data presented are from Abrahamson and Goldman (1970), Flint (1975) and Umek et al.
(unpublished data).
Figure 5. A conceptual model showing potential interactions between deepwater special status species,
their environment, and non-native species. One of the main goals of the proposed study is to determine
which interactions are occurring how these interactions are affecting special status communities.
Proposal: Tahoe Science Program Round 12 Request for Proposals
Figure 6. A map of Lake Tahoe showing sampling locations from a 2008-09 benthic survey (black dots),
sampling locations of a 1962-63 benthic survey (black arrows), and targeted locations for field surveys
described in this proposal (outlined circular areas).