Catherine M. Pringle

• Ph.D Aquatic Biology
• Professor at University of Georgia

Macroconsumers, such as fish, decapod crustaceans, and amphibians, can be important determinants of stream structure and function. In this chapter, we present three types of manipulative field experiments to evaluate top-down effects of macroconsumers in stream food webs and illustrate the role of macroconsumers in shaping the prey communities and...

Emerging infectious diseases can cause host community disassembly, but the mechanisms driving the order of species declines and extirpations following a disease outbreak are unclear. We documented the community disassembly of a Neotropical tadpole community during a chytridiomycosis outbreak, triggered by the generalist fungal pathogen, Batrachochy...

Ecological research has focused on understanding how changes in consumer abundance affect community structure and ecosystem processes. However, there is increasing evidence that evolutionary changes in consumers can also alter community structure and ecosystem processes. Typically, the effects of consumer phenotype on communities and ecosystem proc...

Management of non-point source pollution is of great importance in the context of coffee agriculture, as this land use often coincides with headwater streams that influence water quality at the basin scale. Sustainability certification programs, such as the Rainforest Alliance (RA), provide management guidelines that promote non-point source pollut...

Decades of ecological study have demonstrated the importance of top-down and bottom-up controls on food webs, yet few studies within this context have quantified the magnitude of energy and material fluxes at the whole-ecosystem scale. We examined top-down and bottom-up effects on food web fluxes using a field experiment that manipulated the presen...

Plant litter breakdown is a key ecological process in terrestrial and freshwater ecosystems. Streams and rivers, in particular, contribute substantially to global carbon fluxes. However, there is little information available on the relative roles of different drivers of plant litter breakdown in fresh waters, particularly at large scales. We presen...

We modeled patch occupancy to examine factors that best predicted the prevalence of four functionally important focal stream consumers (Tallaperla spp., Cambarus spp., Pleurocera proxima, and Cottus bairdi) among 37 reaches within the Little Tennessee River basin of the southern Appalachian Mountains, USA. We compared 34 models of patch occupancy t...

ABOUT THIS BOOK In the more than thirty years since the publication of Daniel H. Janzen’s classic Costa Rican Natural History, research in this small but astonishingly biodiverse, well-preserved, and well-studied Latin American nation has evolved from a species-level approach to the study of entire ecosystems. And from the lowland dry forests of Gu...

Human alteration of the global P cycle has led to widespread P loaDing in freshwater ecosystems. Much research has been devoted to the capacity of wetlands and lakes to serve as long-term sinks for P inputs from the watershed, but we know much less about the potential of headwater streams to serve in this role. We assessed storage and retention of...

Freshwater shrimps are an important biotic component of tropical ecosystems. However, they can have a low probability of detection when abundances are low. We sampled 3 of the most common freshwater shrimp species, Macrobrachium olfersii, Macrobrachium carcinus, and Macrobrachium heterochirus, and used occupancy modeling and logistic regression mod...

Species losses are predicted to simplify food web structure, and disease-driven amphibian declines in Central America offer an opportunity to test this prediction. Assessment of insect community composition, combined with gut content analyses, was used to generate periphyton-insect food webs for a Panamanian stream, both pre- And postamphibian decl...

Organic matter may sequester nutrients as it decomposes, increasing in total N and P mass via multiple uptake pathways. During leaf litter decomposition, microbial biomass and accumulated inorganic materials immobilize and retain nutrients, and therefore, both biotic and abiotic drivers may influence detrital nutrient content. We examined the relat...

Many forested headwater streams are heterotrophic ecosystems in which allochthonous inputs of plant litter are a major source of energy. Leaves of riparian vegetation entering the stream are broken down by a combination of biotic and abiotic processes and, in most temperate and boreal streams, provide food and habitat for dense populations of detri...

Geothermally modified ground water (GMG) in tectonically active areas can be an important source of stream nutrients, and the relative importance of GMG inflows is likely to change with shifts in precipitation that are predicted to occur in response to climate change. However, few studies have quantified the influence of GMG inflows on export of bi...

Species losses are predicted to simplify food web structure, and disease-driven amphibian declines in Central America offer an opportunity to test this prediction. Assessment of insect community composition, combined with gut content analyses, was used to generate periphyton-insect food webs for a Panamanian stream, both pre- and post-amphibian dec...

Evolution of life history traits can occur rapidly and has the potential to influence ecological processes, which can also be shaped by abiotic and biotic factors. Few studies have shown that life history phenotype can affect ecological processes as much as commonly studied biotic ecological variables, but currently we do not know how the ecologica...

Taxonomic and functional diversity in freshwater habitats is rapidly declining, but we know little about how such declines will ultimately affect ecosystems. Neotropical streams are currently experiencing massive losses of amphibians, with many losses linked to the chytrid fungus, Batrachochytrium dendrobatidis ( Bd ). We examined the ecological co...

In tropical streams, omnivorous shrimp may be important nutrient recyclers, because they have a lower body P demand than fish. However, little is known about the controls on nutrient recycling by freshwater shrimp. Across a series of lowland tropical streams that range in dissolved P, we describe: (i) shrimp body stoichiometry in relation to stream...

Background/Question/Methods Despite empirical evidence that evolution can influence populations, communities and ecosystems, we do not know if the ecological effects of evolution are frequent and strong enough to regulate communities and ecosystems in nature. We examine how trait variation (diet selectivity and life history) in locally adapted Tr...

Many North American blackwater rivers exhibit low dissolved O2 (DO) that may be the result of benthic respiration. We examined how tree species affected O2 demand via the quantity and quality of litter produced. In addition, we compared areal estimates of surface leaf-litter microbial respiration to sediment O2 demand (SOD) and ecosystem respiratio...

Information about temporal patterns of ecological responses to species losses is integral to our understanding of the ultimate effects of declining biodiversity. As part of the Tropical Amphibian Declines in Streams ( TADS ) project, we quantified changes in algal biomass and N cycling in algae in upland Panamanian streams following the widespread...

1. Information about temporal patterns of ecological responses to species losses is integral to our understanding of the ultimate effects of declining biodiversity. As part of the Tropical Amphibian Declines in Streams (TADS) project, we quantified changes in algal biomass and N cycling in algae in upland Panamanian streams following the widespread...

We applied an integrative framework to illuminate and discuss the complexities of exurbanization in Macon County, North Carolina. The case of Macon County, North Carolina, highlights the complexity involved in addressing issues of exurbanization in the Southern Appalachian region. Exurbanization, the process by which urban residents move into rural...

Research on how N is retained and removed from stream networks has focused on microbial metabolic pathways, such as denitrification. An alternative pathway for N to escape streams is in the form of emerging aquatic insects, and unlike denitrification, previous studies suggest that this pathway may be stimulated by increased availability of P. We te...

[1] The Little River (LR) in southern Georgia, U.S., has experienced lengthening droughts since monitoring began in 1972. We evaluated the impacts of drought on riverine carbon cycling using a 9 year data set of dissolved organic carbon (DOC) coupled with laboratory experiments in the LR, as well as long-term data sets in three additional rivers wi...

Research into the buffering mechanisms and ecological consequences of acidification in tropical streams is lacking. We have documented seasonal and episodic acidification events in streams draining La Selva Biological Station, Costa Rica. Across this forested landscape, the severity in seasonal and episodic acidification events varies due to interb...

Predicting the ecological consequences of declining biodiversity is an urgent challenge, particularly in freshwater habitats where species declines and losses are among the highest. Small-scale experiments suggest potential ecosystem responses to losses of species, but definitive conclusions require verification at larger scales. We measured ecosys...

Background/Question/Methods Ecological processes have long been known to affect evolution, yet only recently has there been experimental evidence of evolution affecting ecological processes. We examine how trait variation (diet selectivity) in Trinidadian guppies affects stream ecosystems at local and landscape scales to address the question: Are...

Background/Question/Methods Losing a key organism or assemblage can be critical for the structure and function of ecosystems potentially causing a complete state change at different scales. In Puerto Rico, migratory shrimps are the most dominant macroconsumer in headwater stream ecosystems and their top-down effects have been shown to regulate be...

Background/Question/Methods As species are extirpated, ecosystem productivity will likely decline with concomitant declines in food web structure as linkages are removed. Catastrophic amphibian extirpations in Central America can affect ecosystem function, but have unknown consequences on food web structure. We empirically assessed periphyton-ins...

Background/Question/Methods Disease epidemics can act as extinction filters, changing community structure, species niche breadth, and species co-occurrence patterns. Rarely do data exist that are collected systematically before and after an epidemic documenting species losses and changes in community composition. We examined spatial and temporal...

Background/Question/Methods The southern Appalachian region is an area of high biodiversity and endemism that is undergoing dramatic changes in land cover due to increasing human population and associated exurbanization. The goal of the Coweeta LTER Hazard SiteProject (CHSP) is to examine how two landscape trajectories, predicted by a hedonic land...

Background/Question/Methods The current focus of our NSF LTREB Project is to examine the extent to which stream ecosystems are resistant and/or resilient to climate-driven acidification in a lowland Costa Rican rainforest. Our overarching LTREB objective is to understand the ecological consequences of ground water - surface water interactions. We...

Despite the typically high taxonomic and functional diversity of tropical habitats, little is known about the roles of individual consumers in their ecosystem structure and function. We studied the trophic basis of production in a tropical headwater stream by identifying major sources of energy, measuring energy flow through consumers and character...

Neotropical streams are losing dominant consumer groups as a result of disease-driven amphibian declines. The herbivorous tadpoles of Lithobates warszewitschii were once abundant in the Rio Maria in the Eastern Cordillera Central of Panama, where they consumed algae and organic matter. The decline of this once abundant grazer has the potential to a...

The freshwater fauna (crustaceans, molluscs, fish) of many tropical islands in the Caribbean and Pacific share an amphidromous life-cycle, meaning their larvae need to develop in saline conditions before returning to freshwater as juveniles. This community dominates the freshwaters of much of the tropics, but is poorly known and at risk from develo...

The importance of terrestrial arthropods has been documented in temperate stream ecosystems, but little is known about the magnitude of these inputs in tropical streams. Terrestrial arthropods falling from the canopy of tropical forests may be an important subsidy to tropical stream food webs and could also represent an important flux of nitrogen (...

Freshwater migratory shrimps, an important component of tropical aquatic ecosystems, are vulnerable to land-use change during their upstream and downstream migrations. At La Selva Biological Station in the Sarapiquí region of Costa Rica, shrimp population data were collected between 1988 and 1989, before massive land-use change occurred downstream...

Light, nutrient availability, and flow are strong factors controlling the elemental composition and biomass of epilithon in temperate stream ecosystems. However, comparatively little is known about these relationships in tropical streams. We investigated how gradients of light and nutrient availability, seasonality, and habitat influenced epilithon...

The effect of consumers on their resources has been demonstrated in many systems but is often confounded by trophic interactions with other consumers. Consumers may also have behavioral and life history adaptations to each other and to co-occurring predators that may additionally modulate their particular roles in ecosystems. We experimentally excl...

Statistical methods for split-plot design and analytical framework for structural and process responses. (DOC)

Benthic invertebrate tallies for control and electrified treatments in three reaches. (DOC)

Acidification in freshwater ecosystems has important ecological and biogeochemical effects. Temperate streams affected by anthropogenic acidification have been extensively studied, but our understanding of natural acidification in tropical streams has been constrained by the lack of long-term datasets. Here, we analyze 14 years of monthly observati...

Background/Question/Methods Altered precipitation regimes caused by global climate change may have dramatic repercussions in aquatic as well as terrestrial ecosystems. In Central American rainforests, increasingly long dry seasons (as predicted by climate models) could have profound effects on stream ecosystems, since dry-season precipitation is...

Background/Question/Methods Changes in consumer assemblages caused by species invasions or losses have significant effects on ecosystem function. These perturbations can also alter organismal phenotypes, but the ecosystem consequences of phenotypic variability are largely unexplored. How important are the ecosystem effects of phenotypic diversifi...

Background/Question/Methods While freshwater shrimps can comprise an obvious and significant proportion of the overall invertebrate biomass and secondary production on tropical island streams, little is known about their role in mainland tropical streams where they often occur at much lower densities and are largely-nocturnally active. In this stu...

Ecological and evolutionary processes may interact on the same timescale, but we are just beginning to understand how. Several studies have examined the net effects of adaptive evolution on ecosystem properties. However, we do not know whether these effects are confined to direct interactions or whether they propagate further through indirect ecolo...

The rapid disruption of tropical forests probably imperils global biodiversity more than any other contemporary phenomenon. With deforestation advancing quickly, protected areas are increasingly becoming final refuges for threatened species and natural ecosystem processes. However, many protected areas in the tropics are themselves vulnerable to hu...

This chapter describes the geologic, geographic, and ecological context of the location of Luquillo Mountains, particularly the factors affecting the response mechanisms of terrestrial and aquatic ecosystems to disturbance. It describes the existing conditions of the physical environment, chemical environment, and the biota of the Luquillo Mountain...

This chapter illustrates the contributions of the Long-Term Ecological Research to the growing awareness of the management of Puerto Rican government in conserving Luquillo Mountains' ecosystem. It also highlights the activities in the Luquillo Experimental Forest (LEF) by addressing the tropical forest conservation issues and relating these to the...

This chapter describes the responses of the organisms, communities, and ecosystems to the variety of disturbances by utilizing the conceptual model discussed in Chapter 2. It also dwells on the concepts of residuals, legacies, and ecological space in the understanding of disturbances such as background treefalls, hurricanes, floods, drought, landsl...

1. Ecological stoichiometry expresses ecological interactions as the balance between multiple elements. It relates the ecological function of organisms to their elemental composition, or their organismal stoichiometry. Organismal stoichiometry is thought to reflect elemental investments in life history and morphology acting in concert with variabil...

Many rural areas of the United States are undergoing increasing development pressure from surrounding metropolitan areas, a phenomenon described as 'exurbanization'. This study examines how stream chemistry in a traditionally rural area of the southern Appalachian Mountains is being influenced by changes in both land cover and land use. Results ill...

The elemental composition of animals, or their organismal stoichiometry, is thought to constrain their contribution to nutrient recycling, their interactions with other animals, and their demographic rates. Factors that affect organismal stoichiometry are generally poorly understood, but likely reflect elemental investments in morphological feature...

Sampling of environmental variables and basal resource quality. (DOC)

Average stoichiometry of epilithon and benthic organic matter (BOM) collected from each site. (DOC)

Least squares (LS) means generated by the stage of maturity×community interaction. (DOCX)

This chapter explores the effects of the organismal diversity to the disturbance sequences that indirectly affects their milieu-the ecosystem. It explains the scientific investigations conducted by the ecologists on the distribution and abundance of organisms, particularly the cycle of nutrients in the food web. It also discusses the flora and faun...

1. Life histories evolve as a response to multiple agents of selection, such as age-specific mortality, resource availability or environmental fluctuations. Predators can affect life-history evolution directly, by increasing the mortality of prey, and indirectly, by modifying prey density and resources available to the survivors. Increasing survivo...

1. Of the relatively few studies that have examined consequences of amphibian declines on stream ecosystems, virtually all have focused on changes in algae (or algal-based food webs) and little is known about the potential effects of tadpoles on leaf decomposition. We compared leaf litter decomposition dynamics in two neotropical streams: one with...

Most hypotheses explaining the general gradient of higher diversity toward the equator are implicit or explicit about greater species packing in the tropics. However, global patterns of diversity within guilds, including trophic guilds (i.e., groups of organisms that use similar food resources), are poorly known. We explored global diversity patter...

Background/Question/Methods Understanding global carbon cycling is increasingly important in a world facing CO2-induced warming. The significance of riverine carbon transport and storage is now widely acknowledged; however, most research on carbon cycling in freshwater systems has been conducted either in temperate zones or in large tropical rive...

Background/Question/Methods Limited aquatic primary productivity is often cited as a factor behind low oxygen levels observed in forested blackwater rivers. However, submerged trunks and knees of the same trees that limit light with their canopy also provide stable substrate for growth of aquatic bryophytes. We use laboratory and field studies to...

Background/Question/Methods Montane Neotropical streams harbor unique aquatic biodiversity and play a critical ecological role at the river basin scale, while draining landscapes increasingly being altered by human activities. Montane Neotropical streams often have high concentrations of endemic species and provide spawning areas or habitat for mi...

Epilithic biofilms are an important and complex food resource in shallow aquatic ecosystems. Standard methods of sampling these biofilms typically yield a combination of algal cells, other organic material, and inorganic sediment. Physical methods of isolating algal fractions rely on differences in density among biofilm components, and clean separa...

Nutrient recycling by animals is a potentially important biogeochemical process in both terrestrial and aquatic ecosystems. Stoichiometric traits of individual species may result in some taxa playing disproportionately important roles in the recycling of nutrients relative to their biomass, acting as keystone nutrient recyclers. We examined factors...

We tested whether assemblages of detritivorous chironomid larvae (Chironomidae: Diptera) varied in phosphorus (P) demand based on local nutrient conditions using a series of streams in lowland Costa Rica that exhibit a natural range in ambient dissolved P and detrital P due to inputs of solute-rich groundwater. Chironomids collected from three high...

Tadpoles are often abundant and diverse consumers in headwater streams in the Neotropics. However, their populations are declining catastrophically in many regions, in part because of a chytrid fungal pathogen. These declines are occurring along a moving disease front in Central America and offer the rare opportunity to quantify the consequences of...

1. We quantified production and consumption of stream‐dwelling tadpoles and insect grazers in a headwater stream in the Panamanian uplands for 2 years to assess their effects on basal resources and energy fluxes. At the onset of our study, this region had healthy, diverse amphibian populations, but a catastrophic disease‐driven decline began in Sep...

Blackwater streams are found throughout the Coastal Plain of the southeastern United States and are characterized by a series of instream floodplain swamps that play a critical role in determining the water quality of these systems. Within the state of Georgia, many of these streams are listed in violation of the state's dissolved oxygen (DO) stand...

Background/Question/Methods While it has long been recognized that ecological factors play a significant role in the evolutionary process, the reciprocal influence of evolutionary change on ecological factors has received less attention. Phenotypic changes can alter the overall role of an organism in the community by changing how that organism di...

Background/Question/Methods Guppy (Poecilia reticulata) populations in streams with different predation regimes exhibit marked differences in their life-history traits. Differences have been attributed to direct effects of predation, but predation may also play a role through its indirect effects on guppy population structure and density and ther...

Background/Question/Methods Acidification of freshwater ecosystems can have harmful biological effects, and the causes and effects of anthropogenic acidification have been well-documented. Effects of seasonality and climate change on natural acidification events have received less attention. In this study, we analyzed a twelve-year dataset of month...

Background/Question/Methods Macroconsumers (fishes, crustaceans) can exert strong top-down effects on ecosystem properties and processes in lotic systems. As part of the NSF-FIBR Trinidad Project, we asked: What are the top-down effects of different macroconsumer taxa on benthic structure and function in Trinidadian high-gradient tropical streams...

Background/Question/Methods: Controls on ecosystem structure and function are often divided into bottom-up and top-down forces. Bottom-up forces include a wide array of physical and chemical factors that influence basal trophic positions while top-down forces control community structure and function through biotic interactions. To explore the relat...

Theory suggests evolutionary change can significantly influence and act in tandem with ecological forces via ecological-evolutionary feedbacks. This theory assumes that significant evolutionary change occurs over ecologically relevant timescales and that phenotypes have differential effects on the environment. Here we test the hypothesis that local...

Aim To use molecular data to test for dispersal structuring in the immigration history of an amphidromous community on an island. Location The Caribbean island of Puerto Rico. Methods Mitochondrial DNA sequences were obtained from 11 amphidromous species, including shrimps, fish and a gastropod, sampled from throughout the island. The timing of pop...

Initial research informing biodiversity–ecosystem functioning (B–EF) theory focused largely on terrestrial plant species richness effects on productivity. Recent studies in stream ecosystems have further advanced understanding of B–EF beyond species richness by testing effects of species diversity (richness and composition) at multiple trophic leve...

A broad perspective on hydrologic connectivity is necessary when managing stream ecosystems and establishing conservation priorities. Hydrologic connectivity refers to the water-mediated transport of matter, energy, or organisms within or between elements of the hydrologic cycle. The potential negative consequences of enhancing hydrologic connectiv...

Todd, M. Jason, George Vellidis, R. Richard Lowrance, and Catherine M. Pringle, 2009. High Sediment Oxygen Demand Within an Instream Swamp in Southern Georgia: Implications for Low Dissolved Oxygen Levels in Coastal Blackwater Streams. Journal of the American Water Resources Association (JAWRA) 45(6):1493-1507. Abstract: Sediment oxygen demand (SOD...

A central tenet of ecological stoichiometry is that consumer elemental composition is relatively independent of food resource nutrient content. Although the P content of some invertebrate consumer taxa can increase as a consequence of P-enriched food resources, little is known about how ecosystem nutrient loading can affect the elemental compositio...

The combination of human population growth, increased water usage, and limited groundwater resources often leads to extensive damming of rivers and streams on tropical islands. Ecological effects of dams on tropical islands can be dramatic, because the vast majority of native stream faunas (fishes, shrimps, and snails) migrate between freshwater an...

One way in which dams affect ecosystem function is by altering the distribution and abundance of aquatic species. Previous studies indicate that migratory shrimps have significant effects on ecosystem processes in Puerto Rican streams, but are vulnerable to impediments to upstream or downstream passage, such as dams and associated water intakes whe...

Various components of island stream faunas, including caridean shrimps, fish, and gastropods, undertake obligate amphidromous migration, whereby larvae are released in upstream freshwater reaches, drift downstream to estuaries or marine waters, then migrate upstream as postlarvae to freshwater adult habitats. Longitudinal migration from estuaries t...

Background/Question/Methods Historical perspectives suggest that evolutionary change is largely dictated by environmental changes in nature. More recent evidence suggests that ecological structure and function may also respond to evolutionary changes in populations leading to potential feedbacks on the evolving organisms. As part of the NSF Fronti...

Background/Question/Methods Whole stream addition of enriched stable isotopes is a powerful method for quantifying biogeochemical cycling and trophic dynamics in lotic ecosystems. However, most isotopic tracer studies have occurred in temperate North American streams, and the approach has been largely neglected in tropical running water systems. U...

Background/Question/Methods The exchange of nutrients between terrestrial and aquatic ecosystems in temperate ecosystems has received increasing attention by ecologists, but little is known about the magnitude of this cross-boundary exchange in the tropics. In tropical rainforests, terrestrial insects falling from the forest canopy have the potent...

Background/Question/Methods Evolution has been shown to be a critical determinant of ecological processes in some systems, but its importance relative to traditional ecological drivers is not well known. In addition, almost nothing is known about the role of ongoing coevolution in shaping ecosystems. One way to gauge the relative importance of evol...

Background/Question/Methods As part of the NSF-Frontiers in Integrative Biological Research (FIBR) Guppy Evolution Project, we asked: what is the role of macroconsumers in structuring benthic communities and driving ecological processes in high gradient Trinidadian streams? We conducted experiments in two stream reaches characterized by 2 differen...

1. Understanding relationships between resource and consumer diversity is essential to predicting how changes in resource diversity might affect several trophic levels and overall ecosystem functioning. 2. We tested for the effects of leaf litter species diversity (i.e. litter mixing) on litter mass remaining and macroinvertebrate communities (taxo...

Evolution has been shown to be a critical determinant of ecological processes in some systems, but its importance relative to traditional ecological effects is not well known. In addition, almost nothing is known about the role of coevolution in shaping ecosystem function. Here, we experimentally evaluated the relative effects of species invasion (...

Approximately 0.5 million km of tropical stream channel are modified by catchment deforestation annually, but the consequences of this process for community structure are poorly understood because of a dearth of data from tropical regions. We compared the algal communities of epilithic biofilms from 3 tropical rainforest streams draining Ranomafana...

Pacific island stream communities are species-poor because of the effects of extreme geographic isolation on colonization rates of taxa common to continental regions. The effects of such low species richness on stream ecosystem function are not well understood. Here, we provide data on community structure and leaf litter breakdown rate in a virtual...

Comparisons of the effects of leaf litter chemistry on leaf breakdown rates in tropical vs temperate streams are hindered by incompatibility among studies and across sites of analytical methods used to measure leaf chemistry. We used standardized analytical techniques to measure chemistry and breakdown rate of leaves from common riparian tree speci...