2007 FMCS SYMPOSIUM
PLENARY SESSION:
DIRECTIONS IN MOLLUSC
CONSERVATION: MOLECULES TO ECOSYSTEMS
ABSTRACTS
PE 01
FRESHWATER BIVALVE (UNIONIFORMES) DIVERSITY, SYSTEMATICS
AND EVOLUTION: STATUS AND FUTURE DIRECTIONS
Arthur E. Bogan1 and Kevin J. Roe2.
North Carolina State Museum of Natural Sciences, Research Lab, 4301 Reedy
Creek Road, Raleigh NC 27607, 2Dept. of Natural Resource Ecology and
Management, Iowa State University, Ames, IA 50011
Freshwater bivalves of the order Unioniformes represent the
largest bivalve radiation in freshwater. This radiation is unique in the class
Bivalvia in having an obligate parasitic larval stage on the gills or fins of
fish. This diverse assemblage is divided into six families, 180 genera and
roughly 800 species. These families are distributed across six of the seven
continents and represent the most endangered group of freshwater animals alive
today. Unioniform bivalves have been the subject of study and illustration
since at least Martin Lister (1675). Over the past 250 years impressive gains
have been made in our understanding of the evolutionary history and systematics
of these animals. We briefly summarize the current state of unioniform
systematics and evolution and suggest research themes for future research.
Advancement in the areas of systematics and evolutionary relationships within
the Unioniformes will require a resurgence of survey work and re-evaluation of
all taxa, especially outside of North America and Western Europe. This will
require collection of animals for shell morphology, comparative anatomy and
molecular analyses. Along with re-examination of described taxa, we need a
renewed emphasis on the natural history, host fish relationships, ecology and
physiology of these animals.
Traditional conchological and anatomical characters need to be reviewed
and new character suites added. New morphometric methods need to be applied to
the ontogenetic changes in shape during growth. The fossil record of freshwater
bivalves needs to be carefully reviewed and a phylogeny of this group needs to
be developed. However, evidence of rampant convergence in shell morphology
needs to be factored out of the record. As our understanding of the systematics
of these animals improves, it will result in a better understanding of the evolution
of this expansive radiation in freshwater. New avenues are being opened in understanding the evolution
of the unioniform bivalves. We need to expand our set of tools to include or
develop additional markers such as single copy nuclear genes and microsatellites.
Examination of double uniparental inheritance of mitochondrial DNA is providing
new insights in to the evolution of this order. Gene order has been shown to
differ among genera but is still to be explored. Expanding our understanding of
the evolutionary relationships and history of unioniform bivalves will provide
a solid foundation to study the zoogeography of these rather sessile, obligate
freshwater organisms. The unique natural history of unioniform bivalves
provides a fertile area for testing and developing evolutionary theories.
PE 02
Life History
strategies of Unionoid mussels
M.C. Barnhart1, G.T. Watters2 1Missouri State University,
Springfield, MO 65897; 2Ohio State University, Columbus, OH 43212
The unique life history strategy of Unionoida is essential
to understanding both the evolutionary success of the group and the present
conservation crisis. The parasitic
larval stage was a key adaptation of the Unionoid ancestor, permitting upstream
dispersal in freshwater. Later
evolutionary diversification was associated with the origin and exploitation of
particular adaptations for parasitizing hosts. Examples of adaptations associated with clades include
hooked glochidia (Unioninae), mantle lures and bradyticty (Lampsilini) and host
capture behavior (Epioblasma). Such adaptations led to varying degrees
of host specificity (use of particular host species), which in turn affected
other aspects of life history and ecology as diverse as fecundity, reproductive
season, habitat, and geographic distribution. Host specialists are more efficient than generalists at
contacting particular host species, but are more constrained in host
utilization and the related aspects of life history. Unionoids in general are long-lived as adults and many species
require several years to reach reproductive maturity. This high somatic investment may allow mussel populations to
persist when reproductive success is unpredictable. The age structure of populations is often strongly biased
toward adults, suggesting that successful recruitment years are
infrequent. These features of life
history and population dynamics may reflect fluctuations in host
availability. They are also likely
to reflect vulnerabilities of the post-parasitic juvenile life stage to environmental
factors, which are poorly known.
Although recent studies by many workers have greatly improved our
understanding of mussel life history, there are tremendous opportunities for
future studies. In particular,
sustained efforts to propagate endangered species and monitor their populations
can provide critical data on the requirements of each life stage and on
population dynamics.
PE 03
A STAGE-BASED MODEL TO INVESTIGATE LINKAGES BETWEEN
DEMOGRAPHIC AND GENETIC FEATURES OF UNIONID POPULATIONS.
David J. Berg1, James A. Stoeckel2,
Todd D. Levine2, and K. Douglas Blodgett3. Department of Zoology, Miami
University, 1Hamilton, OH 45011 or 2Oxford, OH 45056; 3The
Nature Conservancy, Illinois River Project Office at Emiquon, Lewiston, IL
61542
North American freshwater mussels are continuing to suffer
dramatic declines in population size due to a number of anthropogenic stressors
such as habitat destruction and commercial harvest. Within populations, neutral genetic variation is lost
because of genetic drift. The
intensity of drift is negatively correlated with population size. In turn, population size is dependent
on demographic parameters such as mortality, migration, and recruitment
rates. Thus, demographic and
genetic features of populations should be tightly linked. We are developing a stage-based model
to investigate the effects of variation in mortality on population size and
genetic diversity. Demographic
parameters for this model are derived from published data for species of
mussels that exhibit considerable variation in population ecology, while our
own research has provided measures of population genetic variation using a
variety of molecular markers (allozymes, mtDNA sequences, microsatellites) for
many species of mussels across a large portion of North America. Using STELLAŠ
software, our model incorporates a variety of demographic parameters
(age-structure, age-specific mortality, recruitment) and population genetic
parameters (haplotype frequency, heterozygosity). We will use this model to examine effects of constant and
age-specific mortality on populations that have varying levels of genetic
diversity. Results of this model
will provide insight into interactions of demography and population
genetics. For example, we should
be able to compare changes in population size and genetic diversity under
contrasting scenarios of age-specific mortality due to harvest regulations and
constant mortality due to habitat degradation. We will also examine the importance of migration by
comparing isolated populations to populations within a tightly linked
metapopulation. While changes in
population demography are important for estimating extinction risk for
populations in the short-term, survival over evolutionary time is dependent on
maintenance of genetic variation.
Models that incorporate both demographic and genetic features of
populations should be of great utility for the development of effective
conservation strategies.
PE 04
COMMUNITY AND FOODWEB ECOLOGY OF FRESHWATER MUSSELS
Caryn C. Vaughn1, S. Jerrine Nichols2,
and Daniel E. Spooner1.
1Oklahoma Biological Survey and Department of Zoology,
University of Oklahoma, Norman, OK, 73019; 2U.S. Geological Survey. Ann Arbor MI,
48105.
Freshwater mussels link the water column and bottom sediments
through their feeding activities.
All species use gill and/or foot cilia to generate water currents that
bring in suspended food particles. While there are some species differences in
cilia number, spacing, and size, in all species, water enters the shell through
the posterior inhalant siphon and also along the anterior shell margin (pedal
feeding). Thus, all mussel species
can access food particles both suspended in the water column and in the
sediment. Particles are sorted by
the gill cilia and either ingested or biodeposited as mucus-coated
psuedofeces. Research to date
shows that mussel diets are remarkably similar regardless of age, size,
species, or cilia number and size.
Studies using tissue fatty acid profiles, stable isotope ratios, and mussel
digestive enzyme production show that all species feed on particles <20
microns in size, particularly micro-algae and bacteria. In addition, direct assimilation of
organic molecules such as glucose can occur. Based on these similarities, can we assume that all species
perform the same role in foodwebs and communities?
We know that many ecosystem services performed by mussels
(clearance of algae from the water column, nutrient excretion, biodeposition of
organic matter) are linearly related to community biomass; thus, there is the
potential for strong ecosystem effects when mussel biomass is high and
hydrologic residence times are long.
Multiple studies demonstrate that mussels provide biogenic structure and
nutrients to other organisms; algal growth is higher on the shells of living
mussels compared to shells alone, and macroinvertebrate richness and densities
are higher on shells of living mussels and in mussel patches than in other
streambed areas. Effects of mussel
community composition vary with spatial and temporal scales and are regulated
by factors such as temperature, with significant differences between speciesÕ
physiological condition (metabolic rate, body condition) and ecological output
(respiration and excretion rates) under different environmental
conditions. At the scale of a
mussel bed, experiments demonstrate potentially strong interactions between
mussel species with dominant, driver species regulating factors such as
periphyton biomass, but also increasing the body condition of co-occurring
rarer mussel species. At the scale
of whole rivers, species richness becomes important, with different species
driving interactions and ecosystem services under different environmental
conditions. Although more research
is needed, information to date indicates that mussel feeding activities and
community structure can have strong impacts on the entire foodweb, and that
interactions between mussel species are important. Thus, efforts to restore mussels should focus on restoring
entire communities.
PE 05
USING LANDSCAPE ECOLOGY TO UNDERSTAND FRESHWATER MUSSEL
POPULATIONS
Teresa J. Newton1, Daelyn A. Woolnough2,
and David L. Strayer3. 1USGS
Upper Midwest Environmental Sciences Center, La Crosse, WI 54603; 2Biology
Department, Trent University, Peterborough, ON K9J 7B8 Canada; 3Institute
of Ecosystem Studies, Millbrook, NY 12545
Ecology has been transformed over the past 20 years by the
development and application of the landscape ecology subdiscipline, i.e., the
influence of spatial pattern on ecological processes. Mussel populations and the environments they inhabit are
heterogeneous, raising the question:
ÒTo what extent can landscape ecology principles be applied to the
scientific understanding and management of freshwater mussels?Ó We review three areas in which
landscape ecology might be applied to freshwater mussels.
First, mussel ecologists are grappling with how to define
and conceptualize patches of suitable mussel habitat. Recent progress with models and empirical data shows that
hydraulics can be successfully used to delineate patches of mussel
habitat. It is not yet clear
whether hydraulics alone will ultimately provide a satisfactory definition of
mussel habitat, or whether we will need to consider additional variables such as
host fish, food, or predators. As
in other applications of landscape ecology, we do not know whether mussel
ecology will be best served by simple binary patch/matrix models, or if habitat
quality should be viewed as a continuous variable, nor if we will need to model
within-patch dynamics. Special
problems associated with mussel populations include distinguishing ÒfossilÓ
patches in which conditions were suitable for mussel recruitment in the past
from ÒactiveÓ patches in which recruitment still occurs, and the possibility of
strong source-sink dynamics resulting from Allee effects in sparse populations.
Second, mussel ecologists have begun to think about the
importance of connectivity among habitat patches. We would like to know the conditions under which
connectivity among patches is important, and which attributes of the
environment, the mussel species, and its host, determine connectivity among
mussel beds. Major challenges are
determining whether connectivity can be estimated in the field, whether human
activities that reduce connectivity (e.g., dams) have produced large extinction
debts in mussel populations, and whether connectivity is strongly directional
in running waters.
Third, recent studies have shown that characteristics of the
watershed (especially land use) affect mussel populations. This work is still in an early stage,
and needs to be critically tested.
We also need to better understand the links between events on the
watershed (e.g., timing and amounts of water, nutrient, and sediment inputs,
condition of the riparian zone) and the quality, extent, location, and
connections among patches of mussel habitat. In addition, it is critical to identify the locations on the
watershed that have the strongest links to mussel populations.
Landscape ecology has the potential to improve scientific
understanding and management of mussel populations, and in particular help
define the best spatial scales for scientific studies and management
activities. However, terrestrial
paradigms will need to be used carefully.
PE 06
FRESHWATER MUSSEL ECOSYTEM ECOLOGY: THE INTEGRATED FUNCTIONAL ROLES OF
WATER QUALITY, POLLUTION, AND PHYSICAL HABITAT IN SUPPORTING ADULT AND EARLY
LIFE STAGES OF FRESHWATER MUSSELS AND THEIR ROLE IN NUTREINT RECYCLING
W.G. Cope1, A.D. Christian2,
R.B. Bringolf1, N. Wang3, T.J. Newton4, J.L.
Farris2, T. Augspurger5, F.J. Dwyer6, M.C.
Barnhart7, R.J. Neves8, E. Hammer9, and C.G.
Ingersoll3. 1North
Carolina State University, Raleigh, NC 27695-7633; 2Arkansas State
University, State University, AR 72467; 3U.S. Geological Survey,
Columbia, MO 65201; 4U.S. Geological Survey, La Crosse, WI 54603; 5U.S.
Fish and Wildlife Service, Raleigh, NC 27636-3726; 6U.S.
Fish and Wildlife Service, Columbia, MO 65201; 7Missouri State
University, Springfield, MO 65897; 8Virginia Tech University,
Blacksburg, VA 24061-0321; 9U.S. Environmental Protection Agency,
Chicago, IL 60604-3590.
A recent assessment of the published literature on the
topics of water quality, pollution, and physical habitat and their roles in
supporting adult and early life stages of freshwater mussels revealed two types
of informational sources contributing to our current understanding of
environmental health. Descriptive
field-based studies showed that mussels have been adversely affected by poor
water quality and associated pollutants, and loss and degradation of physical
habitat. Noted site-specific
effects, contaminant accumulation, as well as global declines were documented
by these studies. Based on these
observations and the development of ASTM International standard methods for
conducting laboratory toxicity tests with early life stages of freshwater
mussels, recent experimental-based studies have attempted to determine links,
causal mechanisms, and establish rigorous testing and assessment methods. We evaluated the routes and pathways of
exposure for all life stages (glochidia, encysted, juveniles, adults) of native
freshwater mussels to environmental pollutants, in a life history and ecosystem
ecology context, and found that each life stage has both common and unique
characteristics that contribute to observed differences in sensitivity and
exposure. For example, glochidia
may be exposed only briefly (e.g., 1-12 days) through the water column, whereas
juveniles and adults have sustained exposure through the water column, pore
water, sediment and dietary routes.
Juveniles and adults differ in their primary habitat and feeding
mechanisms; thereby altering the importance of these routes in exposure,
depending on life stage. This
synthesis has shown that a combination of life history and ecosystem-level
ecological information is needed to properly assess the risks of environmental
exposure. Knowledge of differing
habitat-based exposure routes on mussel life stages is critical to
understanding the relation and applicability of recently developed ASTM
International standard acute and chronic laboratory toxicity test methods for
predicting toxicological risk and the ultimate protection and conservation of
the mussel fauna. In terms of the
role of freshwater mussels in ecosystem processes, a review of the literature
has shown that mussels play an important role in nutrient recycling. Mussels
feed on materials variable in C:N:P, use these nutrients for growth, and egest
materials variable in C:N:P.
Nutrients used for growth can be sequestered for long periods of time,
whereas egested material may become readily available for subsequent trophic
interactions. Freshwater mussels
perform vital functional roles in ecosystem processing.
PE 07
DIRECTIONS AND INFORMATION NEEDS FOR FRESHWATER MUSSEL
CONSERVATION
Richard J. Neves1 and Heidi Dunn2 .1Virginia
Cooperative Fish and Wildlife Research Unit, U.S. Geological Survey, Virginia
Tech, Blacksburg, VA 24061; 2Ecological Specialists, Inc., 1417 Hoff
Industrial Court, OÕFallon, MO 63366
Conservation of freshwater biodiversity should be the
highest priority in the U.S., based on global significance of our resident
taxonomic groups and number of species susceptible to extinction over the next
decade. Trends in demand for land,
water, and energy indicate that means for conserving mussel resources while
allowing for economic growth must be determined. Developing long-term plausible solutions will require
coordination with other scientific disciplines, engineers, resource managers,
developers, and higher levels of government. Current mussel conservation and management ranges from basic
life history research to improvement of habitat conditions to facilitate mussel
community maintenance and enhancement.
In addition to actions presented as goals and strategies in the National
Strategy for the Conservation of Native Freshwater Mussels about 10 years ago,
information is needed to catapult our taxon-specific discipline to a more
quantitative, scientifically defensible, and user friendly level. Our knowledge of mussel biology would
increase greatly if sister disciplines include mussels as study animals in
their areas of expertise, such as toxicology, population biology, veterinary
medicine, physiology, biochemistry, biological engineering, and other such
complementary sciences. We need
field-level tools to determine baseline physical, cellular, and
population-level conditions, and detect responses to physical and chemical
stress on both the cellular and population level. Development of appropriate biomarkers would fill this gap.
Greater knowledge of mussel habitat requirements and the effects of change on
mussels are also needed in mussel conservation. Coordinating with personnel such as hydrologists,
geomorphologists, and civil engineers can provide suitable techniques for
measuring key habitat parameters.
However, sustainable development and mussel conservation must have the
support of governmental agencies, as field biologists often are inhibited by archaic
policies and procedures. Higher
levels of government must be educated on the importance of mussel conservation,
and the need for policy changes to allow this effort to go forward. Additionally, engineers, developers,
and resource managers must coordinate with mussel biologists on the front-end
of private projects or government programs, such that mussel conservation needs
are accommodated in the planning process rather than as an afterthought. Techniques such as mussel propagation
for enhancing and restoring mussel populations, stream restoration to improve
habitat, mussel toxicology to test water quality standards, and mussel sampling
and monitoring to detect changes in mussel communities are being conducted. However, effectiveness of implementing
these techniques in mussel conservation and management depends on our ability
to better understand mussel biology and coordinate with outside
disciplines. Although we have
progressed in the last 10 years, mussel conservation needs are more acute, as
most endangered populations continue to decline. A combination of mussel expertise, other biological
expertise, regulatory agencies, and engineering disciplines will provide the
toolbox of actions required to allay the currently projected extinction rate.
PE
08
FRESHWATER
GASTROPOD ECOLOGY AND CONSERVATION DIRECTIONS
Kathryn E. Perez1,
Russell L. Minton2, Kenneth M. Brown3, Jeffrey D. Sides4,
Steven J. Lysne5. 1University of North Carolina at Chapel Hill
& Department of Biology, Duke University, Durham, NC 27708. 2Department
of Biology, University of Louisiana at Monroe, Monroe, LA 71209. 3Department
of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803. 4Department
of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294. 5U.S.
Fish and Wildlife Service, Boise, ID 83709.
North
American freshwater snails remain an understudied yet critically imperiled
fauna. As part of a larger discussion on freshwater mollusks in general, we
highlight five specific areas of concern regarding freshwater snails, and
discuss how best to address those concerns in the context of conservation:
ecology, taxonomy and systematics, the impact of invasives and other future
threats, the needs of state and federal agencies for prioritization and
implementation of management plans, and the role of the non-governmental groups
and outreach for preservation of these natural treasures. We illustrate the how
each of these topics relate to conservation efforts and present synthetic and
prioritized research goals to improve our baseline knowledge of freshwater
snail biology. For ecology, we review the literature on freshwater gastropods,
identifying important trends and highlighting the importance of ecological data
in studying these groups. A necessary precursor to conservation efforts is an
adequate assessment of biological diversity. We present the current state of
freshwater snail taxonomy, and show how modern methods such as population and
molecular genetics have affected our understanding of natural evolutionary
units and the identification of species.
Invasive species have affected freshwater taxa across North America,
through competition, habitat modification and parasitism to name a few. These alien species originate not only
in other countries, but also in neighboring drainages and systems as native
taxa become exotic through human-mediated introductions. We outline currently
recognized and potential threats to native species and the impacts they are
having and may have in the future.
Finally, effective conservation strategies require the participation of
people at all levels, from local communities to governmental agencies, for
implementation and management. We summarize the status and efficacy of
freshwater snail captive propagation, as well as partnerships with
non-governmental organizations, federal agencies, and other stakeholders.
Suggestions for the future direction of multi-partner cooperation in freshwater
snail conservation are discussed.
PE 09
A New National Freshwater Mollusk conervation
society Strategy for Conservation of Native Freshwater Mollusks
Rachel C. Muir1
and Robert M. Anderson2.. 1U.S.
Geological Survey, Biological Resources Division, Mailstop 131 National Center,
Reston, VA 20102, 2 U.S. Fish and Wildlife Service, Pennsylvania Ecological Services Field
Office, State College, PA, 16801.
The National Strategy for the
Conservation of Native Freshwater Mollusks (Strategy) was developed a decade
ago, prior to the establishment of the FMCS. Since the Strategy was published there have been significant
changes in the conservation status of freshwater mollusks, the kind and degree
of threats to aquatic ecosystems and mollusks, and in the state of our
knowledge of freshwater mollusks. A revised and current National Strategy can
serve as a guidance document for the FMCS in its support of mollusk
conservation, research and monitoring as well as FMCS policy and
activities. The purpose of the
session is to present a draft strategy to the Society and provide an
opportunity for the exchange of ideas between the FMCS National Strategy
subcommittee and the FMCS membership. The format will be a panel, with
subcommittee members presenting specific recommendations for revision. These
will include the topics addressed in the current National Strategy and new
issues such as conservation
genetics, propagation, adaptive management, expanded outreach, and coordination
with other organizations and conservation efforts such as the National Fish
Habitat Initiative. The resulting
input will be incorporated into a document for FMSC board approval by June,
2007.