The upper Gila River basin in southwest New Mexico, USA is one of the few unimpounded drainage basins in North America and is a stronghold for the unique and endemic fishes west of the Continental Divide. Multiple non-indigenous fishes have been introduced to the Gila River and are a potential threat to native fishes, yet very little is known of the trophic ecology of the native and nonnative fishes. We used diet and stable isotopes collected from native and nonnative fishes to identify their trophic relationships and evaluate potential interactions in the upper Gila River basin during June-July, 2007 and 2008. Diet and stable isotope data indicated aquatic invertebrates were the primary food for both native and nonnative fishes. Native large-bodied fishes were mainly algivore/detritivores and native small-bodied fishes were primarily insectivores. Small-bodied nonnative fishes fed on detritus and aquatic invertebrates. Nonnative predators preyed on small-bodied fishes and predaceous aquatic invertebrates and had higher trophic positions than all native fishes. Although nonnative predators did not rely exclusively on native fishes as prey, their presence extended community food-chain lengths, and the combined predation on juvenile native fishes by multiple apex predators may threaten persistence of native fishes. The lack of concise evidence for negative effects suggested that impacts of nonnative predators were more subtle and confirmed the underlying complexity of a relatively simple community The extensive database on feeding relations of Gila River fishes allowed us to further understand how energy moves through ecosystems. Specifically, the goal of chapter two was to characterize variation in fish-community food web structure within and among study reaches on the Gila River using [superscript]13C and [superscript]15N stable isotopes. We hypothesized that food web structure would reflect variation in fish community structure, resource availability and environmental conditions across habitats. Food web structure in isotope bi-plot space was estimated using community-wide measures of trophic structure, mean trophic position, and food-chain length. Permutational multivariate analysis of variance indicated that indices of food web structure were more variable among than within reaches and this pattern was primarily associated with variation in trophicl area occupied by taxa in isotope bi-plot space and mean trophic position of those taxa. Variation in food web structure was significantly associated with fish species richness across macrohabitats but was weakly associated with abiotic reach-scale factors. Variation in food web structure was concordant with variation in fish community composition and suggested that factors influencing the distribution of fishes also influence food web structure.

Methods in Stream Ecology provides a complete series of field and laboratory protocols in stream ecology that are ideal for teaching or conducting research. This two part new edition is updated to reflect recent advances in the technology associated with ecological assessment of streams, including remote sensing. Volume focusses on ecosystem structure with in-depth sections on Physical Processes, Material Storage and Transport and Stream Biota. With a student-friendly price, this Third Edition is key for all students and researchers in stream and freshwater ecology, freshwater biology, marine ecology, and river ecology. This text is also supportive as a supplementary text for courses in watershed ecology/science, hydrology, fluvial geomorphology, and landscape ecology. Methods in Stream Ecology, 3rd Edition, Volume 2: Ecosystem Structure, is also available now! Provides a variety of exercises in each chapter Includes detailed instructions, illustrations, formulae, and data sheets for in-field research for students Presents taxonomic keys to common stream invertebrates and algae Includes website with tables and a link from Chapter 22: FISH COMMUNITY COMPOSITION to an interactive program for assessing and modeling fish numbers Written by leading experts in stream ecology

Embedded in ecosystems are non-random stabilizing structures that allow ecosystems to persist in the face of environmental variability. Food web structure is a vital part of this architecture because it determines the flow of energy and nutrients through ecosystems. Food web structure is flexible because it reliably changes with environmental conditions in time and space, thus promoting ecosystems' capacity to adapt. Flexible food web structure arises when species exhibit rapid, predictable responses to environmental change through shifts in foraging behaviour based on their traits. Ecologists have examined the foraging responses of only single species, but understanding the flexibility of whole food webs requires examining the foraging responses of the many species that comprise ecosystems; however, studying whole food web flexibility requires detailed, large-scale food web data on short timescales. In this thesis, I study the Canadian boreal shield lakes to expand our understanding of flexibility in the whole food webs structure in three important ways. In Chapter 2, I show that key food web members display paired foraging and behavioural responses to increased temperature, generating flexible food web structure along multiple axes. In Chapter 3, I use behaviour as a proxy for feeding data to show that species within thermal guilds display aggregate behavioural responses that imply whole food webs flex with warming. In Chapter 4, I determine that DNA-based stomach content analysis increases prey detection and food web resolution relative to traditional morphological approaches, implying this technique could reveal subtle foraging shifts and flexes in food web structure on short timescales. Taken together, my thesis (a) establishes that numerous species consistently respond to environmental variability based on their traits and drive predictable flexes in whole food web structure that will determine the impacts of climate change on entire ecosystems, and (b) demonstrates that ecologists possess the complementary toolset necessary to study rapid flexes in food web structure. I conclude that species responses represent a potentially powerful, repeated mechanism to stabilize food webs and that flexibility of whole food webs supports the notion that ecosystems are indeed complex adaptive systems. Importantly, human activities erode this flexibility, but by embracing variability, we can seek ways to conserve the fundamental stabilizing structures ingrained throughout ecosystems.

Woody wetlands constitute a relatively small but extremely important part of the landscape in the southwestern United States. These riparian habitats support more than one-third of the regionÕs vascular plant species, are home to a variety of wildlife, and provide essential havens for dozens of migratory animals. Because of their limited size and disproportionately high biological value, the goal of protecting wetland environments frequently takes priority over nearly all other habitat types. In The Ribbon of Green, hydrologists Robert H. Webb, and Stanley A. Leake and botanist Raymond M. Turner examine the factors that affect the stability of woody riparian vegetation, one of the largest components of riparian areas. Such factors include the diversion of surface water, flood control, and the excessive use of groundwater. Combining repeat photography with historical context and information on species composition, they document more than 140 years of change. Contrary to the common assumption of widespread losses of this type of ecosystem, the authors show that vegetation has increased on many river reaches as a result of flood control, favorable climatic conditions, and large winter floods that encourage ecosystem disturbance, germination, and the establishment of species in newly generated openings. Bringing well-documented and accessible insights to the ecological study of wetlands, this book will influence our perception of change in riparian ecosystems and how riparian restoration is practiced in the Southwest, and it will serve as an important reference in courses on plant ecology, riparian ecology, and ecosystem management.

Warren, Jr.

Coverage: 1982- current; updated: monthly. This database covers current ecology research across a wide range of disciplines, reflecting recent advances in light of growing evidence regarding global environmental change and destruction. Major ares of subject coverage include: Algae/lichens, Animals, Annelids, Aquatic ecosystems, Arachnids, Arid zones, Birds, Brackish water, Bryophytes/pteridophytes, Coastal ecosystems, Conifers, Conservation, Control, Crustaceans, Ecosyst em studies, Fungi, Grasses, Grasslands, High altitude environments, Human ecology, Insects, Legumes, Mammals, Management, Microorganisms, Molluscs, Nematodes, Paleo-ecology, Plants, Pollution studies, Reptiles, River basins, Soil, TAiga/tundra, Terrestrial ecosystems, Vertebrates, Wetlands, Woodlands.