| Ecology and
Paleobiology of Marine Benthic Communities
Research Interests
The
History of Regional Outbreaks of Coral Disease on Caribbean
Reefs
The staghorn coral Acropora cervicornis was a dominant
space-occupier and an important framework constructor of
Caribbean coral reefs during the Pleistocene and Holocene.
Populations of Acropora were killed throughout the
region in the 1980s and 1990s by outbreaks of white-band
disease, a presumed bacterial infection. On lagoonal reefs
in Belize, the demise of Acropora led to dominance by
the lettuce coral Agaricia tenuifolia. This Acropora-to-Agaricia
transition produced a clear signature in the subsurface
sediments in Belize, and analysis of cores extracted from
these reefs showed this sequence of events to be unique in
at least the last 3,000 years. Similar Agaricia-dominated
communities are common today in Bahía Almirante, a coastal
lagoon at Bocas del Toro in northwestern Panama, more than
1,000 km from the Belizean reefs. Supported by grants from
the National Science Foundation, the National Geographic
Society and the Smithsonian Institution, we conducted an
intensive program of coring to determine whether the
Panamanian reefs have a similar history to those in Belize.
In Panama we discovered that the transition was from
branching Porites
to Agaricia,
rather than from Acropora
to Agaricia. As in Belize, the shift was unprecedented in the past
several thousand years, but the cause was different. In
Panama, biogeochemical studies suggest that shifting
patterns of land use, related primarily to agricultural
development, were responsible for the transition to Agaricia.
Our current efforts are focused on the Pacific coast of
Panama, where a severe El Niño event in 1982–83 wiped out
vast populations of the branching coral Pocillopora damicornis. We are coring reefs in the Gulf of Panama
and the Gulf of Chiriquí to determine whether that coral
mass mortality was a unique historical event, or whether
similar coral kills occurred in the past.
Global Climate Change and the Evolutionary Ecology of
Mollusks in Antarctica
Global climate change late in the Eocene epoch (about 35
million years ago) had an important influence in Antarctica.
This was the beginning of the transition from a
cool-temperate climate in Antarctica to the polar climate as
we know it today. The cooling trend strongly influenced the
structure of shallow-water, Antarctic marine communities,
and these effects are still evident in the peculiar
ecological relationships among species living in modern
Antarctic communities. Cooling late in the Eocene reduced
the abundance of fish and crabs, which in turn reduced
skeleton-crushing predation on invertebrates. Reduced
predation allowed dense populations of ophiuroids (brittlestars)
and crinoids (sea lilies) to appear in shallow-water
settings at the end of the Eocene. These low-predation
communities appear as dense fossil echinoderm assemblages in
the upper portion of the late Eocene La Meseta Formation on
Seymour Island, off the Antarctic Peninsula. Today, dense
ophiuroid and crinoid populations are common in
shallow-water habitats in Antarctica but generally have been
eliminated by predators from similar habitats at temperate
and tropical latitudes; their persistence in Antarctica to
this day is an important ecological legacy of climatic
cooling in the Eocene. Although the influence of declining
predation on Antarctic ophiuroids and crinoids is now
well-documented, the effects of cooling on the more abundant
mollusks have not been investigated. During field
expeditions to Seymour Island in 2000–2003 we collected
material to examine the evolutionary ecology of gastropods
and bivalves in Antarctica during the late Eocene.
Along with colleagues from the University of Illinois,
we are testing evolutionary hypotheses based on the
predicted responses of mollusks to declining temperature and
changing levels of predation. Seymour Island contains the
only fossil outcrops readily accessible in Antarctica from
this crucial period in Earth history. The La Meseta
Formation on Seymour Island thus provides a unique
opportunity to learn how climate change affected Antarctic
marine communities. In practical terms, global climate
change is warming the waters around the Antarctic Peninsula.
Recent ecological evidence suggests that skeleton-crushing
predators are in the process of reinvading subtidal
habitats, which is cause for concern. Understanding the
response of the La Meseta faunas to global cooling in the
late Eocene will provide direct insight into the rapidly
changing structure of modern benthic communities in
Antarctica.
Macroecology Applied to Management of Coral Reefs
Will the
small-scale biological and physical processes revealed by
experimental studies be reflected in long-term, regional
dynamics? Supported by grants from NOAA's Sanctuaries and
Reserves Division, we are conducting a long-term,
biogeographic-scale program to track corals, sponges, algae
and other sessile organisms in fully-protected zones (FPZs)
and on reference reefs within the Florida Keys National
Marine Sanctuary. Video and photographic records enable us
to detect changes in coral cover, diversity, and recruitment
success, and to determine the contributions of large- and
small-scale disturbances to those changes. We are especially
interested in the landscape- to regional-scale predictors of
coral diversity and in the changeover from coral-dominated
to algal dominated reef communities. These topics are of
special concern not only to ecologists, but to managers and
policymakers.
Ecosystem Development in Restored Salt
Marshes in Alabama
Salt marshes provide ecosystem services that include
critical habitat for commercially important crustaceans
and fish, and energy export to adjacent estuarine
habitats. The goal of most marsh restoration efforts along
the Atlantic and Gulf coasts has been to replant the
smooth cordgrass, Spartina
alterniflora, and monitor its subsequent
re-establishment. The assumption has been that some
approximation of natural ecosystem function will follow
the provision of structure at the water’s edge. This
assumption generally has not been corroborated. The
blue crab, Callinectes
sapidus, is the basis of important commercial
fisheries along the Gulf Coast and it is the keystone
predator of salt marshes in the southeastern United
States. Although Callinectes
and many of their mobile prey species rapidly colonize
created/restored marsh habitats, it is not clear whether
natural or near-natural trophic relationships become
established. Likewise, it is unclear when restored marshes
begin to provide significant prey resources to support Callinectes
populations. The
marsh periwinkle, Littoraria
irrorata, is an abundant and conspicuous herbivore in Spartina
marshes along the Gulf Coast. Callinectes
is a generalist predator, and it is the primary predator
of Littoraria.
By controlling Littoraria
populations, Callinectes
prevents cascading ecosystem effects, which under some
conditions include overgrazing and the loss of Spartina.
The long-term success of restoration efforts thus depends
in large part on the establishment and maintenance of
trophic linkages such as this Callinectes–Littoraria interaction.
The goal of this study is to compare the degree of
ecosystem development in restored salt marshes of varying
ages to the state of nearby reference marshes. We are
assessing community structure as faunal abundance, biomass
and diversity, using flume traps and pit traps for the
mobile epifauna, and sediment cores for the infauna. We
are measuring energy flux through analysis of crab gut
contents and fecal material. Predator-prey dynamics are
being examined through a set of proven parameters of
predation, which have been validated and positively
correlated in pilot studies: (1) attacks on Littoraria
in tethering experiments; (2) sublethal shell repair in Littoraria
populations; (3) induced morphological defenses of Littoraria shells; and (4) the abundance of Callinectes. Physical/biological structure - i.e., Spartina
density - will be measured, along with densities of Littoraria,
using standard quadrat survey methods. We are using these
densities in tandem with Callinectes
densities to determine how Spartina
itself influences predation on Littoraria.
We have just begun this study, so results are not
available at this time.
Selected
Publications
Moody, R. M. and R. B.
Aronson. 2007. Trophic heterogeneity in salt marshes of
the northern Gulf of Mexico. Marine Ecology Progress
Series 331:49-65. PDF
of Publication©
Aronson, R. B. and W. F. Precht. 2006. Conservation, precaution, and Caribbean reefs. Coral Reefs 25:441-450.
PDF
of Publication©
MacIntyre, I. G. and R. B. Aronson.
2006. Lithified and unlithified Mg-calcite precipitates in
tropical reef environments. Journal of Sedimentary
Research 76:81-90.
Precht, W. F. and R. B. Aronson.
2006. Death and resurrection of Caribbean coral reefs: a
paleoecological perspective. Pp. 40-77, In:
I. Côté and J. Reynolds (Eds.), Coral Reef
Conservation. Cambridge University Press, Cambridge
UK.
Aronson, R. B., I. G. Macintyre, S. A. Lewis and N. L. Hilbun. 2005.
Emergent zonation and geographic convergence of coral reefs. Ecology
86:2586-2600. Copyright © 2005 by the Ecological Society of America. PDF
of Publication©
Aronson, R. B., I. G. Macintyre and W. F. Precht. 2005. Event preservation in lagoonal
reef systems. Geology 33:717-720. Geological Society of America, P.O.
Box 9140, Boulder, CO 80301-9140 USA (http://www.geosociety.org).
Aronson, R. B., W. F. Precht, T. J. T. Murdoch and M. L. Robbart. 2005. Long-term
persistence of coral assemblages on the Flower Garden Banks, northwestern
Gulf of Mexico: implications for science and management. Gulf of Mexico
Science 23:84-94. PDF
of Publication©
Precht, W. F. and R. B.
Aronson. 2004. Climate flickers and range shifts of reef
corals. Frontiers in Ecology and the Environment 2:307-314.
Copyright ©
2004 by the Ecological Society of
America. PDF of
Publication©
Aronson, R. B., I. G.
Macintyre, C. M. Wapnick and M. W. O'Neill. 2004. Phase shifts,
alternative states, and the unprecedented convergence of two reef
systems. Ecology 85:1876-1891. Copyright ©
2004 by the Ecological Society of America. PDF of Publication©
Wapnick, C. M., W. F. Precht and R. B.
Aronson. 2004. Millennial-scale dynamics of staghorn coral at
Discovery Bay, Jamaica. Ecology Letters 7:354-361.
PDF of
Publication©
Aronson, R. B., I. G.
Macintyre, W. F. Precht, T. J. T. Murdoch and C. M. Wapnick. 2002.
The
expanding scale of species turnover events on coral reefs in Belize.
Ecological Monographs 72:233-249. Copyright ©
2002 by the Ecological Society of America. PDF of Publication©
Aronson, R. B., W. F.
Precht, M. A. Toscano and K. H. Koltes. 2002. The 1998 bleaching event
and its aftermath on a coral reef in Belize. Marine Biology 141:435-447. Copyright©
2004 by the Ecological Society of America. PDF of Publication©
Aronson,
R. B.
and W. F. Precht. 2001. White-band disease and the changing face of Caribbean coral reefs. Hydrobiologia
460:25-38.
Aronson, R. B., K. L. Heck Jr. and J. F. Valentine. 2001.
Measuring predation with tethering experiments. Marine Ecology Progress Series
214:311-312. PDF of Publication©
Aronson, R. B., W. F. Precht, I. G. Macintyre and T. J. T. Murdoch.
2000. Coral bleach-out in Belize. Nature 405:36.
PDF of Publication©
Aronson, R. B. and W. F. Precht. 2000. Herbivory and algal dynamics on the coral reef at Discovery Bay, Jamaica.
Limnology and Oceanography 45:251-255.
Murdoch, T. J. T. and R. B. Aronson. 1999. Scale-dependent spatial variability of coral assemblages along the Florida Reef Tract.
Coral Reefs
18:341-351. PDF
of Publication©
Aronson, R. B. and R. E. Plotnick. 1998. Scale-independent interpretations of macroevolutionary dynamics. Pages 430-450 in
M. L. McKinney and J. A. Drake, eds. Biodiversity dynamics: turnover of populations, taxa and communities.
Columbia University Press, New York.
Aronson, R. B., W. F. Precht and I. G. Macintyre. 1998.
Succession and species replacement on a Holocene reef in the Belizean shelf lagoon.
Coral Reefs 17:223-230. PDF of
Publication©
Richardson, L. L., W. M. Goldberg, K. G. Kuta, R. B. Aronson, G. W. Smith,
K. B. Ritchie, J. C. Halas, J. S. Feingold and S. L. Miller. 1998.
Florida's mystery coral killer identified. Nature 392:557-558.
Aronson, R. B., D. B. Blake and T. Oji. 1997. Retrograde community structure in the late Eocene of Antarctica.
Geology 15:903-906.
Aronson, R. B. and W. F. Precht. 1997. Stasis, biological disturbance, and community structure of a Holocene coral reef.
Paleobiology 23:326-346.
Aronson, R. B., P. J. Edmunds, W. F. Precht, D. W. Swanson and
D. R. Levitan. 1994. Large-scale, long-term monitoring of Caribbean coral reefs: simple, quick, inexpensive techniques.
Atoll Research Bulletin 421:1-19. PDF
of Publication©
Current
Research Grants
National Geographic Society (2005-2007); Land Use and Reef Development in Central America.
Alabama Center for Estuarine Studies (2006-2008); Impacts of Salt-Marsh Restoration on Ecosystem Function and Export to Estuarine Environments.
Alabama Department of Conservation and Natural Resources (2005-2007); Trophic Dynamics of a Created Salt Marsh in Coastal Alabama.
NOAA Coastal Ocean Program (2004-2006); Ecological Processes
Driving Recovery of Coral Reefs in the Florida Keys.
| Current
Graduate Students |
Postdoctoral Associates |
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|
Nancy Hilbun
Thad Murdoch |
Ryan Moody |
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