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Richard B. Aronson

Senior Marine Scientist 
Professor, University of South Alabama

Ph.D., 1985, Harvard University


R Aronson
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


Nancy Hilbun
Thad Murdoch

Ryan Moody











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