A hugely important text for advanced undergraduates as well as graduates with an interest in stream and river ecology, this second, updated edition is designed to serve as a textbook as well as a working reference for specialists in stream ecology and related fields. The book presents vital new findings on human impacts, and new work in pollution control, flow management, restoration and conservation planning that point to practical solutions. All told, the book is expanded in length by some twenty-five percent, and includes hundreds of figures, most of them new.

Nutrient enrichment is common in Irish streams yet despite extensive reports of algal nutrient requirements, generally, this study found no differences in algal biomass across a wide nutrient gradient. In addition, increases in light levels resulted in no net change in algal biomass. Nevertheless, greater densities of grazing benthic macroinvertebrates (grazers), principally Baetis rhodani, were found in high nutrient, high light streams. The ability of grazers to effectively prevent the accrual of highly productive algae was demonstrated through a series of invertebrate grazer exclusion experiments. These experiments also revealed greater grazing pressures at more nutrient rich sites, presumably a function of greater productivity of the grazers{u2019} algal food source. Top-down grazer control of algae was also shown to be highly variable in time and space. Vigorous algal growth during periods of reduced grazing pressure resulted in rapid accrual of the nuisance filamentous alga Cladophora glomerata. Established filaments developed a degree of grazer resistance and there was evidence that these filaments benefitted from the presence of microphyte grazers, suggesting that grazing pressure can shift between a negative and a positive force depending on algal morphology. High-flow events overrode all other interactions and effectively reduced previously accrued algal biomass to levels near zero yet did not negatively effect grazers. Post-spate algal-invertebrate interactions were subsequently reverted to grazer top-down control. During a prolonged low-flow period, Cladophora in shaded habitats accrued to similar levels as in unshaded habitats. These results indicate that despite light-limited growth, algal biomass can attain similar levels over time in shaded habitats, the threshold of which is governed by flow conditions. This study has demonstrated the dominant roles that small bodied grazers and hydraulic disturbance play in regulating algal standing stock in streams in south-west Ireland. These aspects of stream ecosystem function deserve greater attention from a stream management perspective.

Relative effects of light, nutrients, and grazing on primary production were investigated in streams in the Cascade Mountains of Oregon and in laboratory streams. Relative magnitudes of primary production and associated processes were examined for one year in a stream that flowed through a clearcut and an old-growth forest in the Cascade Mountains. Diel patterns of nutrients in four streams of different size indicated greater demand for inorganic nitrogen than phosphorus and suggested that uptake by aquatic primary producers was responsible for diel fluctuations of nutrient concentrations. Atomic ratios of N/P supported the conclusion that primary producers were most probably nitrogen limited. In an experiment of light and nitrate addition to a stream in an old-growth forest, primary producer processes were enhanced by addition of light (11000 lux) and by addition of both light and nitrate. There was no effect of nitrate addition on accumulation of algae, gross primary production, net community primary production, community respiration, P/R ratios, or community structure of diatoms at low ambient light levels (1100 lux). Addition of light resulted in greater colonization of algae, gross primary production, net community primary production, community respiration, P/R ratios and altered community structure of diatoms. The watershed was clearcut one year later and the experiment was essentially repeated with artificial shading instead of artificial lighting. Responses of colonization and primary production to light and nitrate in the clearcut were similar to those observed in the previous experiment in the old-growth forest. Interactions between primary producers and grazers in lotic systems were examined in laboratory streams. Different densities of snails were established in laboratory channels; primary production in these channels was compared to production in a channel without grazers. Heavy and intermediate grazing resulted in decreases in standing crop of chlorophyll a, biomass/chlorophyll ratios, biomass of periphyton, gross primary production, and net community primary production. Low grazing densities did not significantly alter the above factors. Gross primary production increased with increasing standing crop of chlorophyll a but assimilation number was much greater at low standing crops; therefore, there was a partial compensatory mechanism for adjustment to grazing pressure. Total primary production was approximately equal at both high and intermediate densities of grazers and was greater at low densities of grazers and no grazing. Taxonomic structure of periphyton was altered by heavy and intermediate grazing but not changed at low grazing pressures. Snail growth increased with increasing biomass of periphyton. Responses of aquatic primary producers to canopy removal were examined in a clearcut and old-growth forest section of a stream in the Cascade Mountains of Oregon. Standing crop of chlorophyll a, biomass of periphyton, community respiration, assimilation number, and respiration per unit weight of periphyton were all significantly greater in the clearcut than in the old-growth forested section. Gross primary production was approximately 2.5 times greater in the open section than in the shaded section. Turnover times of periphyton were shorter in the clearcut than in the old-growth forest site. Photosynthetic efficiency was greater in the shaded site than in the open section. Processes of primary production were generally enhanced in the clearcut section of Mack Creek as compared to the old-growth forested section. Shifts of food bases in streams from allochthonous material to autochthonous primary production may have major effects on structure and function of stream ecosystems. Succession of energy bases is best viewed in terms of overall watershed succession. Aquatic primary producers are an integral component of stream ecosystems and a major determinant of the nature and dynamics of higher trophic levels in streams.

Environmental problems in coastal ecosystems can sometimes be attributed to excess nutrients flowing from upstream watersheds into estuarine settings. This nutrient over-enrichment can result in toxic algal blooms, shellfish poisoning, coral reef destruction, and other harmful outcomes. All U.S. coasts show signs of nutrient over-enrichment, and scientists predict worsening problems in the years ahead. Clean Coastal Waters explains technical aspects of nutrient over-enrichment and proposes both immediate local action by coastal managers and a longer-term national strategy incorporating policy design, classification of affected sites, law and regulation, coordination, and communication. Highlighting the Gulf of Mexico's "Dead Zone," the Pfiesteria outbreak in a tributary of Chesapeake Bay, and other cases, the book explains how nutrients work in the environment, why nitrogen is important, how enrichment turns into over-enrichment, and why some environments are especially susceptible. Economic as well as ecological impacts are examined. In addressing abatement strategies, the committee discusses the importance of monitoring sites, developing useful models of over-enrichment, and setting water quality goals. The book also reviews voluntary programs, mandatory controls, tax incentives, and other policy options for reducing the flow of nutrients from agricultural operations and other sources.

"National Water-Quality Assessment Project."

Algae are an important component of aquatic benthic ecosystems because they reflect the health of their environment through their density, abundance, and diversity. This comprehensive and authoritative text is divided into three sections to offer complete coverage of the discussion in this field. The first section introduces the locations of benthic algae in different ecosystems, like streams, large rivers, lakes, and other aquatic habitats. The second section is devoted to the various factors, both biotic and abiotic, that affect benthic freshwater algae. The final section of the book focuses on the role played by algae in a variety of complex freshwater ecosystems. As concern over environmental health escalates, the keystone and pivotal role played by algae is becoming more apparent. This volume in the Aquatic Ecology Series represents an important compilation of the latest research on the crucial niche occupied by algae in aquatic ecosystems. - Presents algae as the important player in relation to environmental health - Prepared by leading authorities in the field - Includes comprehensive treatment of the functions of benthic algae as well as the factors that affect these important aquatic organisms - Acts as an important reference for anyone interested in understanding and managing freshwater ecosystems

... Summarizes water quality data at selected wadeable streams; examines the response of algae to nutrients and incident light from June through September 2001 and provides potential methods for nutrient criteria development ...

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

Advances in Algal Biology: A Commemoration of the Work of Rex Lowe was written by students and colleagues of Rex Lowe to acknowledge his esteemed career that included exceptional contributions to research and teaching. Papers in the book cover a variety of topics in algal ecology, focusing on benthic algal ecology in freshwater ecosystems. The studies provide an unusual combination of small-scale experiments and large-scale regional surveys that bridge both basic and applied ecology. Ecologists, limnologists, phycologists, and environmental scientists will find valuable contributions to the development and application of algal research.