Associate
Professor of Biology
Hartwick
College
|
Address |
Biology
Department, Hartwick College, Oneonta, NY 13820 |
|
Office |
337 Johnstone Science Center |
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Telephone |
(607)-431-4768 |
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Fax |
(607)-431-4374 |
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E-mail |
= Top==Education==Research==Publications===Courses==Links==
My research lies at the interface of behavioral, population,
and community ecology. I am broadly interested in the mechanisms (e.g.,
behaviors) involved in intra- and interspecific interactions and how these
interactions affect populations and communities. My general approach is to
develop a thorough, mechanistic understanding of a community and its component
populations. Since sound ecological theories require an understanding of
mechanisms and a firm foundation of empirical data, this type of research is
important for the further growth of ecology.
In 1999, I started a quantitative sampling program to
determine the distribution and abundance of crayfish species in creeks and
rivers in the Pine Lake area (Kuhlmann & Hazelton, 2007).
The main focus is a non-native species, the rusty crayfish, Orconectes
rusticus. Sometime after 1969, the rusty crayfish was introduced
into the upper Susquehanna River and has since spread into many
tributaries. Rusty crayfish are native to the Ohio River but have been
recently introduced to many rivers and lakes throughout the upper Midwest and
Northeastern US and southern Canada. Most research on introduced
populations of rusty crayfish has been done in lakes in Wisconsin, where the
species is known to displace native crayfish species and alter the composition
of lake communities. Much less is known about the effects of introduced
rusty crayfish in streams. The overall objectives of this research
program are to 1) monitor the distribution of introduced and native crayfish in
the upper Susquehanna River and its tributaries, 2) examine the mechanisms that
allow the rusty crayfish to invade stream habitats, and 3) determine the
effects of rusty crayfish on local stream communities. Comparing the
mechanisms and effects of O. rusticus’s invasion of streams to previous findings in
lakes will provide ecologists with a broader understanding of the causes and
consequences of species introductions.
The mottled sculpin is a
stream-dwelling, shelter-nesting fish that is distributed widely in North
America. During the breeding season (spring and early summer), male sculpins occupy cavities under rocks and other stream
debris. Females lay eggs in a discrete mass inside the nest of a male,
who then fertilizes and guards the eggs until they hatch.
Interactions
– Mottled sculpin
and rusty crayfish (Orconectes rusticus)
share a suite of predators, especially large fish like smallmouth bass (Micropterus dolomieu),
and use the same refuges (rocks) to avoid predators. As a result, the presence of one of these species may affect
the other’s interaction with predators, either by influencing refuge use by the
prey or altering the predators’ behavior.
Ongoing student research involves experiments in outdoor artificial
pools to compare the mortality rates and behaviors of crayfish and sculpin with and without smallmouth bass predators. The experiment will allow us to
determine if the presence of alternate prey has an effect on bass predation on
crayfish and sculpin. The behavioral observations will allow us to determine the
mechanism of any observed effects.
Mating
systems ecology - Mating systems
theory attributes variation in mating strategies (patterns of mate choice and
competition) to variation in the availability of resources required for
reproduction. Shelter-nesting fish are excellent for mating systems
research because the critical resource, the nest, is easily identifiable. Also,
resource availability is likely to vary greatly in nature and the resource can
often be easily manipulated experimentally. Initial phases of
research on sculpin mating strategies have included:
1) gathering baseline population data, such as distribution, abundance, size
structure, and reproduction; 2) pilot experiments to assess the feasibility of
field manipulations; and 3) laboratory shelter competition experiments.
Initiated in 2003, this project aims to survey the
coastal habitats of San Salvador Island, Bahamas, to determine the abundance
and distribution of juvenile spiny lobster (Panulirus argus) and juvenile lobster habitat.
My objective is to investigate potential life-history bottlenecks that
may limit the abundance of adult spiny lobsters around San Salvador Island, in
the context of gaining a broader understanding of the ecology and dynamics of P. argus
population ecology. This research will add to the understanding of the
population ecology of a commercially- and ecologically-important marine
species, the Caribbean spiny lobster. Much of what we know about spiny
lobster population ecology comes from studies in the Florida Keys, although the
ecological conditions there are not representative of much of the spiny
lobster’s range. This study will expand that knowledge by examining the ecology
of P. argus
in a different ecological setting.
Past research, in collaboration with A. H. "Tuck"
Hines of the Smithsonian Environmental
Research Center, aimed at understanding the role of interspecific
interactions in regulating populations and the behavioral mechanisms driving
these interactions. We investigated the significance of a predator's functional
response on its prey's population in a model predator-prey system: the blue
crab, Callinectes sapidus,
preying on the Baltic clam, Macoma balthica, in the upper Chesapeake Bay (Kuhlmann & Hines, 2005). Theory suggests that certain
types of predator functional responses, the relationship between prey density
and the proportion of prey a predator eats, might promote prey population
stability. Earlier research showed that, in laboratory mesocoms,
individual blue crabs eat proportionally fewer clams at lower prey densities.
Thus, the clams should have a partial refuge from predation at low densities,
allowing the prey population to persist in the presence of the predator. We
extended this research by addressing two main questions: 1) Does the functional
response of individual predators in the lab predict patterns of prey mortality
in the field, when multiple predators will be involved? 2) What behavioral
mechanisms in the predator are responsible for the patterns of prey mortality?
We addressed these questions with a combination of mesocosm
and field studies to measure clam mortality rates and blue crab foraging
behavior under a variety of conditions. The functional response of individual
blue crabs does not predict the patterns of clam mortality in the field; that
is, the effect of a population of blue crabs is different than the effects of
an individual. Thus, blue crab behavior in the field, either in terms of
foraging or distribution, must be different than that of individual crabs in
isolation. Agonistic behaviors were not significantly affected by clam density,
but the presence of a conspecific increased a crab’s
foraging time at the lowest clam density. Changes in behavior when
multiple crabs forage together may partly account for the reduction in density
dependence of clam mortality. Predator responses such as the effects of conspecifics on foraging and patch choice that were lacking
in the laboratory appear to be key in determining prey mortality patterns in
the field. Larger-scale patterns of prey density variation were more
important in determining prey mortality rates than the small-scale variation
represented by the experimentally-manipulated patches.
A second project investigated how refuges from
predation modify both the direct and indirect effects of interspecific
interactions in an estuarine community of moderate trophic
complexity. Although the effects of refuge are well documented for simple
communities, little is known about its effects on complex trophic
interactions in more diverse communities. Because of indirect effects, the
impacts of refuge in more diverse communities are not easily predicted from
simpler systems. In the upper Chesapeake Bay, coarse woody debris (CWD) is used
by the grass shrimp Palaemonetes pugio and an
intermediate predator, the mummichog Fundulus heteroclitus,
as a refuge from larger predators (of both species), especially the white perch
Morone americana. We
found that grass shrimp altered their use of shelter depending on what
predators were present: shrimp aggregated at CWD when no predators, white perch
only, or both white perch and mummichog were present
in experimental mesocoms, but avoided the refuge in
the presence of mummichogs only.
My dissertation research focused on indirect effects in
multi-species interactions and on nonconsumptive or nontrophic (i.e., not predation or competition)
interactions, particularly the effects of biologically created shelters.
Indirect effects occur when the interaction between two species is influenced
by a third species. Mathematical models suggest that indirect effects can
greatly affect the stability and complexity of species interactions within
communities, but our current understanding of their importance or of the
mechanisms involved is far from complete. Indirect effects involving nontrophic interactions are particularly poorly documented,
since most empirical and theoretical studies have emphasized the roles of
predation and/or competition.
I investigated nontrophic
indirect effects in seagrass communities, primarily in St. Joseph Bay in the
northeastern Gulf of Mexico. My research focused on interactions between a
predatory marine gastropod (the horse
conch, Pleuroploca gigantea) and
an assemblage of benthic fishes and invertebrates that shelter and/or lay eggs
in the empty shells left after the death of the gastropod's main prey, the pen shell Atrina rigida. If it is a major source of Atrina mortality, the gastropod could regulate
shelter availability, and thus indirectly affect populations of the species
that use the shells for shelter and/or reproduction. If changes in pen shell
availability affect some species more strongly than others, horse conchs may
also indirectly influence community composition.
My research investigated two components of the
indirect effect: (1) the effect of horse conchs on Atrina mortality and (2) the effects of pen shell availability on the
occupant species. Conch exclusion experiments, foraging observations and
sampling indicate that horse conchs are the main source of Atrina mortality (Kuhlmann, 1994). However, while Atrina made up >90% of horse conchs'
observed diet, conchs did not show a functional or numerical (i.e., aggregation)
response to pen shell density (Kuhlmann, in press). These results suggest Atrina mortality rate, that is, the
availability of new shelters, will be determined primarily by horse conch
abundance rather than Atrina density. Shell addition experiments
demonstrated that three species of fish (two blennies
and a clingfish) responded most strongly to shelters mimicking freshly killed Atrina (Kuhlmann, 1994).
Since the fishes use the shells not only for shelter but also as a site for reproduction, the gastropod predator may
influence both local abundance and reproductive output, which potentially
affects individual fitness. Subsequently, I conducted a four-month quantitative
manipulation of Atrina mortality rate and measured both
abundance and reproductive responses in the fishes. Atrina
mortality rate significantly affected reproductive output at both the level of
the individual and the population in one species, the Florida blenny, Chasmodes saburrae (Kuhlmann, 1997).
I also collected extensive data on Atrina population dynamics (recruitment, growth, and mortality rates),
dynamics of the shell resource (fouling and loss rates), and shell utilization
patterns during several years of sampling in St. Joseph Bay (Kuhlmann,1998).
I combined the data from the conch foraging observations, shell manipulation
experiments, and Atrina and shell sampling to construct a
stochastic simulation model of this interaction web. This model will help me
tease apart the effects of the multiple interacting factors involved in the
indirect effect and can be used to make quantitative predictions of the effect
of horse conchs on fish reproduction under a variety of conditions. I can then
test these predictions in the field by directly manipulating horse conch
density and measuring the effect on the fishes. This experiment is important
because few, if any, models of interspecific interactions are ever tested
empirically, and because a manipulation of horse conch density would be a
definitive test of our understanding of the system.
I have also conducted research in a number of other areas. I
have documented large differences in body size between two populations of the
crab Pilumnus sayi that
appear to be caused by differences in the sizes of available shelters. I have
collaborated with another student in our lab (R. Walker) to measure the
reproductive consequences of these size differences (Kuhlmann
and Walker, 1999). My master's thesis research investigated behavioral
predator-avoidance mechanisms in an intertidal hermit crab. Most research on
hermit crabs has focused on shell selection as an antipredator
measure; my study did not find any strong effect of shell type but demonstrated
that predator-specific behavioral responses reduced predation risk (Kuhlmann, 1992). I also have conducted research on
bird-mediated seed dispersal of gap-dwelling plants in Costa Rica (Murray et al., 1994).
= Top==Education==Research==Publications===Courses==Links==
Kuhlmann, M.L. 1992. Behavioral
avoidance of predation in an intertidal hermit crab. Journal of Experimental
Marine Biology and Ecology 157: 143-158.
Murray, K.G., S. Russell, C.M.
Picone, K. Winnett-Murray,
W. Sherwood and M.L. Kuhlmann. 1994. Fruit laxatives and seed passage rates in frugivores: consequences for plant reproductive success.
Ecology 75: 989-994.
Kuhlmann, M.L. 1994. Indirect
effects of a predatory gastropod in a seagrass community. Journal of
Experimental Marine Biology and Ecology 183: 163-178.
Kuhlmann, M.L. 1997.
Regulation of fish reproduction by a predatory gastropod: an experimental
investigation of indirect effects in a seagrass community. Journal of
Experimental Marine Biology and Ecology 218: 199-214.
Kuhlmann, M.L. 1998.
Spatial and temporal patterns in the dynamics and use of shell shelters in St.
Joseph Bay, Florida. Bulletin of Marine Science 62: 157-179.
Kuhlmann, M.L. and R.
Walker. 1999. Geographic variation in size structure and size at maturity
in the xanthid crab Pilumnus sayi in the northern Gulf of Mexico.
Bulletin of Marine Science 64: 535-541.
Allen, M. E., and M. L. Kuhlmann. 2002.
Search for the Missing Sea Otters: An Ecological Detective Story. [A
teaching case study]. Published online at the Case Study
Collection - National Center for Case Study Teaching in Science
Kuhlmann, M. L., and A. H.
Hines. 2005. Density-dependent predation by blue crabs Callinectes sapidus on
natural prey populations of infaunal bivalves.
Marine Ecology Progress Series 295: 215-228. pdf
Kuhlmann, M. L. April
2006, posting date. Do Antbirds Help or Hinder Army
Ants? Teaching Issues and Experiments in Ecology, Vol. 4: Issues Figure Set #1
[online]. http://tiee.ecoed.net/vol/v4/issues/figure_sets/army_ants/abstract.html
Kuhlmann, M. L., and P. D. Hazelton. 2007.
Invasion of the upper Susquehanna River watershed by rusty crayfish, Orconectes rusticus. Northeastern Naturalist 14:507-518.
Kuhlmann, M. L., S. M. Badylak,
and E. L. Carvin. 2008. Testing
the differential predation hypothesis for the invasion of rusty crayfish in a
stream community: laboratory and field experiments. Freshwater Biology 53:
113-128. Available online at: http://www.blackwell-synergy.com/toc/fwb/53/1
Murray, K.G., K. Winnett-Murray,
J. Roberts, K. Horjus, W.A. Haber, W. Zuchowski, M. Kuhlmann, and T.M. Long-Robinson. 2008.
The roles of disperser behavior and physical habitat structure in regeneration
of post-agricultural fields. Pp. 192-215, in R.W. Myster
(editor): Post-agricultural succession in the Neotropics.
Springer. 308 pages.
Kuhlmann, M. L. 2008. Do invading rusty crayfish
interfere with reproduction in a native congener? Journal of Crustacean Biology 28: 461-465.
Kuhlmann, M. L.
2009. Fish as fertilizer: the impacts of salmon on coastal ecosystems.
Published online at the Case Study Collection - National Center for Case Study
Teaching in Science (http://www.sciencecases.org/salmon_forest/case.asp)
= Top==Education==Research==Publications===Courses==Links==
On-line course information for recent or current
courses without links above may be available through Hartwick College Blackboard server.
= Top==Education==Research==Publications===Courses==Links==