Description:    Shallow water habitat (SWH) is important for riverine fish and their invertebrate prey, yet the availability of SWH has declined in many systems due to human impacts. We evaluated the potential ecological benefits of restoring SWH by comparing zooplankton and phytoplankton from created backwaters (a floodplain feature connected to the river on the downstream end but disconnected at the upstream end) and chutes (a side channel of the river that diverts flow from the main channel through the chute and back into the main channel) on the lower Missouri River. We tested the hypothesis that backwaters support higher abundances of zooplankton and phytoplankton than chutes using data that were collected during the summer of 2010. As predicted, backwaters had more diverse cladoceran communities and greater abundances of rotifers, copepod nauplii, adult copepods, and cladocerans than chutes. Total algal biovolume was the same in chutes and backwaters; however, phytoplankton taxa richness was higher in backwaters, and there was a greater biovolume of green algae ( Chlorophyta ), Crypotophyta, cyanobacteria, and Euglenophyta in backwaters than in chutes. Differences in zooplankton and phytoplankton between backwaters and chutes appeared to be related to slower current velocities, longer retention times, and lower levels of turbidity and total suspended solids in backwaters. While chutes have the potential to provide greater habitat diversity than the mainstem, there were no differences in water quality or phytoplankton abundance, community structure, or diversity between these two habitats. Combined, our results suggest that created backwaters initially provide a greater potential food resource for native fishes. However, additional research is needed to determine whether chutes can also develop beneficial shallow water features over a longer period of time. Content Type Journal Article Pages 1-12 DOI 10.1007/s10452-012-9421-0 Authors Andrew R. Dzialowski, Department of Zoology, Oklahoma State University, Stillwater, OK 74074, USA Joseph L. Bonneau, Threatened and Endangered Species Section, U.S. Army Corps of Engineers, Yankton, SD, USA Todd R. Gemeinhardt, Environmental Resources Section, U.S. Army Corps of Engineers, Kansas City, MO 64106, USA Journal Aquatic Ecology Online ISSN 1573-5125 Print ISSN 1386-2588

Description:    We evaluated the response of the zooplankton community Saginaw Bay, Lake Huron to the disappearance of the planktivore alewife Alosa pseudoharengus using data collected in 1991–1996 (pre alewife decline) and 2009–2010 (post alewife decline). Bosmina longirostris , Diaptomidae, Cyclops , and Daphnia galeata contributed greatly to the separation of the two time periods with Diaptomidae and D. galeata increasing and Cyclops and B. longirostris decreasing, although B. longirostris remained the dominant species. Peak densities of zooplankton occurred in early summer (June) in the 1990s and in early fall (October) in 2009–2010. For the analysis of environmental variables on a bay-wide, annual basis, abundance of alewife, age-0 yellow perch Perca flavescens and Bythotrephes captured much of the variation in annual zooplankton community structure. Abundances of Bythotrephes and age-0 yellow perch were both higher in 2009–2010 than in 1991–1996. Some changes such as increasing proportions of calanoid copepods reflect a more oligotrophic community and are potentially indicative of resource-driven changes rather than direct or indirect impacts of the alewife disappearance. Content Type Journal Article Pages 1-12 DOI 10.1007/s10452-012-9420-1 Authors Steven A. Pothoven, National Oceanic and Atmospheric Administration, Great Lakes Environmental Research Laboratory, 1431 Beach Street, Muskegon, MI 49441, USA Tomas O. Höök, Department of Forestry and Natural Resources, Purdue University, 195 Marstellar St., West Lafayette, IN 47907, USA Thomas F. Nalepa, National Oceanic and Atmospheric Administration, Great Lakes Environmental Research Laboratory, 4840 S. State Road, Ann Arbor, MI 48108, USA Michael V. Thomas, Michigan Department of Natural Resources, Lake St. Clair Fisheries Research Station, 33135 South River Road Harrison Twp., Mt. Clemens, MI 48045, USA Julianne Dyble, National Oceanic and Atmospheric Administration, Great Lakes Environmental Research Laboratory, 4840 S. State Road, Ann Arbor, MI 48108, USA Journal Aquatic Ecology Online ISSN 1573-5125 Print ISSN 1386-2588

Description:    The development of a community through time, or succession, is generally described as the orderly replacement of species until a deterministic, stable endpoint is reached. However, stochastic factors, coupled with intrinsic biotic factors, such as herbivory or predation, can cause communities within the same habitat to become highly dissimilar in composition. Much research on the succession of terrestrial systems has been conducted, but factors influencing the succession of a terrestrial system may not apply to aquatic systems. To determine whether succession in an aquatic system is deterministic or dominated by contingency of stochastic factors, and the role that higher trophic level interactions and resources have in shaping successional patterns, I followed community development and dynamics of the intermediate and bottom trophic level (protozoans and bacteria) in the model Sarracenia purpurea pitcher plant system throughout an entire growing season. By comparing these dynamics across pitcher plant leaves within the same bog, I was able to determine whether there is a predictable pattern for community assembly in this aquatic community. The results from this study suggest that rather than a sequential replacement of early colonizers with more competitive species through time, competitively superior species establish in newly formed communities simultaneously with less competitive species, which coexist throughout the growing season. Community assembly in this system can also be altered by stochastic events. Resources and predators had a variable effect on the patterns of community change observed during succession. Patterns of community assembly were also dependent on the trophic level examined but, for the bottom trophic level, not on the sampling method used. Content Type Journal Article Pages 1-13 DOI 10.1007/s10452-012-9417-9 Authors Sarah M. Gray, Department of Ecology and Evolution, Stony Brook University, 650 Life Sciences Building, Stony Brook, NY 11794-5245, USA Journal Aquatic Ecology Online ISSN 1573-5125 Print ISSN 1386-2588

Description:    By shaping the architecture and taxonomic composition of periphyton, stream current may create periphytic mats on which some grazers can feed and forage more effectively than others. Current-mediated periphytic structure also has the potential to foster positive interactions among grazers if one grazer’s foraging facilitates another’s access to algal food. To examine the extent to which these indirect effects of current influenced periphytic removal and grazer interactions, we conducted a mesocosm experiment with two common grazers, the caddisfly (Trichoptera) Glossosoma verdona and the mayfly (Ephemeroptera) Drunella grandis . Periphyton was allowed to colonize ungrazed tiles for 30 d and assume its natural growth form under three ranges of near-bed current, “slow” (1–5 cm s −1 ), “medium” (15–20 cm s −1 ), and “fast” (30–40 cm s −1 ). Tiles were then exposed to the two grazer species at five densities. A streambed survey quantified Glossosoma and Drunella distributions in relation to near-bed current and periphytic structure (i.e., diatom films vs. filamentous mats) in the Colorado River. After 22 days of grazing, periphytic removal by Glossosoma was influenced by near-bed current and attendant periphytic structure. In slow current, where senescent Ulothrix filaments were abundant, increased Glossosoma density was correlated with an increase in periphyton biomass. Larvae became entangled and immobilized by the diffuse and senescent Ulothrix mat that characterized slow velocity, and Glossosoma mortality and weight loss was greatest in this treatment. By contrast, Drunella reduced periphyton across all density and current treatments. Drunella density correlated with increased Glossosoma survivorship and weight gain in slow current. The driving mechanism for this facilitation appeared to be removal of entangling overstory filaments by Drunella . The streambed survey showed that Glossosoma were negatively associated with filamentous mats, lending support to the hypothesis that clearing action by Drunella in the slow current/senescent Ulothrix treatment facilitated Glossosoma growth and survival. Our study helps underscore the importance of evaluating species interactions over ranges of abiotic conditions and consumer pressure to understand the patterns and processes shaping benthic communities. Content Type Journal Article Pages 1-10 DOI 10.1007/s10452-012-9419-7 Authors Todd Wellnitz, Biology Department, University of Wisconsin–Eau Claire, Eau Claire, WI 54701, USA N. LeRoy Poff, Biology Department, Colorado State University, Ft. Collins, CO 80523, USA Journal Aquatic Ecology Online ISSN 1573-5125 Print ISSN 1386-2588

Description:    Recently, major advances in the climate–zooplankton interface have been made some of which appeared to receive much attention in a broader audience of ecologists as well. In contrast to the marine realm, however, we still lack a more holistic summary of recent knowledge in freshwater. We discuss climate change-related variation in physical and biological attributes of lakes and running waters, high-order ecological functions, and subsequent alteration in zooplankton abundance, phenology, distribution, body size, community structure, life history parameters, and behavior by focusing on community level responses. The adequacy of large-scale climatic indices in ecology has received considerable support and provided a framework for the interpretation of community and species level responses in freshwater zooplankton. Modeling perspectives deserve particular consideration, since this promising stream of ecology is of particular applicability in climate change research owing to the inherently predictive nature of this field. In the future, ecologists should expand their research on species beyond daphnids, should address questions as to how different intrinsic and extrinsic drivers interact, should move beyond correlative approaches toward more mechanistic explanations, and last but not least, should facilitate transfer of biological data both across space and time. Content Type Journal Article Pages 1-19 DOI 10.1007/s10452-012-9418-8 Authors Csaba Vadadi-Fülöp, Hungarian Scientific Research Fund Office, Czuczor u. 10, 1093 Budapest, Hungary Csaba Sipkay, Danube Research Institute of the Hungarian Academy of Sciences, Jávorka Sándor u. 14, 2131 Göd, Hungary Gergely Mészáros, Szent István University, Páter Károly u. 1, 2100 Gödöllő, Hungary Levente Hufnagel, Department of Mathematics and Informatics, Corvinus University of Budapest, Villányi út 29-43, 1118 Budapest, Hungary Journal Aquatic Ecology Online ISSN 1573-5125 Print ISSN 1386-2588

Description:    To date, most research on cyanobacterial blooms has focused on high-nutrient, not low-nutrient lakes. We investigated reports of the cyanobacterium Gloeotrichia echinulata in lakes with low concentrations of nitrogen and phosphorus across the northeastern United States by surveying selected oligotrophic and mesotrophic lakes during four summers. G. echinulata is a large (1–3 mm diameter) colonial cyanobacterium that may have substantial effects on low-nutrient lakes used for drinking water and recreation because it can produce the toxin microcystin-LR. We found G. echinulata in the water column of 27 out of 37 lakes we sampled in Maine, New Hampshire, New York, and Vermont. G. echinulata densities were typically low (〈5 colonies L −1 ), but occasionally at surface scum-producing levels (up to 250 colonies L −1 ). G. echinulata colonies from the survey lakes exhibited detectable microcystin-LR concentrations ranging from 58 to 7,148 ng microcystin-LR g −1 dry weight colonies. If G. echinulata densities increase to bloom levels observed in eutrophic systems, our data suggest that the microcystin-LR concentrations attributable to G. echinulata may reach levels known to influence aquatic organisms and pose human health risks. Content Type Journal Article Pages 1-15 DOI 10.1007/s10452-012-9409-9 Authors Cayelan C. Carey, Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA Holly A. Ewing, Program in Environmental Studies, Bates College, Lewiston, ME 04240, USA Kathryn L. Cottingham, Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA Kathleen C. Weathers, Cary Institute of Ecosystem Studies, Millbrook, NY 12545, USA R. Quinn Thomas, Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA James F. Haney, Center for Freshwater Biology, Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA Journal Aquatic Ecology Online ISSN 1573-5125 Print ISSN 1386-2588

Description:    The objective of this study is to evaluate impacts of different management scenarios for American lobster ( Homarus americanus ) and Atlantic cod ( Gadus morhua ) fisheries on the dynamics of ecosystem for the lobster in the Gulf of Maine (GOM). The GOM lobster supports one of the most economically valuable commercial fisheries in the northeastern United States. The GOM ecosystem has experienced a great change over the last two decades, switching from a groundfish-dominated ecosystem to a lobster-dominated ecosystem. An evaluation of the GOM ecosystem dynamics can help identify possible causes of such a change and improve our understanding of interactions between lobster and other species in the same ecosystem. In this study, we developed a 24-group Ecosim model to quantify the ecosystem dynamics in the GOM from 1985 to 2007. We developed a Monte Carlo simulation approach to incorporate uncertainties for 15 most sensitive vulnerabilities. We found that the GOM ecosystem dynamics could be generally well simulated using the Ecosim model compiled in this study. A high fishing mortality in cod could result in high lobster stock biomass, suggesting that higher fishing pressure on cod in the 1980s might contribute to the high lobster biomass in recent years. A higher fishing mortality for lobster would have led to a lower lobster biomass. The change in the fishing mortality of cod and lobster would also affect the biomass dynamics of other functional groups, indicating that the Atlantic cod and American lobster fisheries played an important role in the change of the GOM ecosystem in the last two decades. Content Type Journal Article Pages 1-14 DOI 10.1007/s10452-012-9414-z Authors Yuying Zhang, School of Marine Sciences, University of Maine, Orono, ME 04469, USA Yunkai Li, School of Marine Sciences, University of Maine, Orono, ME 04469, USA Yong Chen, School of Marine Sciences, University of Maine, Orono, ME 04469, USA Journal Aquatic Ecology Online ISSN 1573-5125 Print ISSN 1386-2588

Description:    In spite of the existence of a number of papers applying the biomarker approach using pigments or akinetes to discuss the impact of cyanobacteria on the functioning of lakes in the palaeoenvironmental context, their sedimentary imprint in the form of microcystins (MCs) has never been taken into consideration. Our objective was to reconstruct 200 years of the development of chironomid assemblages in a shallow Polish lake with notoriously blooming toxic cyanobacteria. A 50-cm long sediment core sampled from the central part of the lake was sliced every 1 cm, dated, and analysed for the subfossil remains of Chironomidae and concentrations of MCs. The fauna underwent four distinct stages in its recent history: three periods when the assemblages were typical of hypertrophic conditions (the first one comprising the entire nineteenth century, and the second and third one including approximately the last 30 years of the twentieth century), separated by a “eutrophic” assemblage during the first 70 years of the twentieth century. The typical features of the “eutrophic” midge assemblage were high total densities and high values of taxonomic richness and diversity. This period coincided with relatively low concentrations of MCs in the sediments. Sediments from the hypertrophic periods were distinguished by taxonomic impoverishment of chironomids, low Shannon diversity index, a strong decrease in chironomid numbers, and high concentrations of MCs. Significant negative correlations with MCs along the sediment profile were observed for eurytopic chironomids. MC concentrations were also negatively but not significantly correlated with total density of chironomids, their benthic and epiphytic assemblages, species richness, and diversity index. Content Type Journal Article Pages 1-9 DOI 10.1007/s10452-012-9415-y Authors Anna Kaczorowska, Department of Hydrobiology, University of Life Sciences in Lublin, Dobrzańskiego 37, 20-262 Lublin, Poland Ryszard Kornijów, Department of Fisheries Oceanography and Marine Ecology, National Marine Fisheries Research Institute, Kołłątaja 1, 81-332 Gdynia, Poland Journal Aquatic Ecology Online ISSN 1573-5125 Print ISSN 1386-2588

Description:    This study examines two aspects of predator-induced, morphological defense in rotifers: developmental time lags for acquisition and loss of the defense, and cost of the defense. When the predator and its inducing kairomone disappear from a community, the extent to which prey population growth is inhibited by the retention of the induced defense will be determined by the reversibility of the defense and the magnitude of any cost associated with the defense. In Brachionus calyciflorus , Asplanchna -induced posterior spines were lost more slowly than acquired. When females of the induced morph were removed from Asplanchna kairomone after oviposition of their first egg, they continued to produce long-spined offspring throughout their life. Even when cultured from birth to death without Asplanchna kairomone, females born with long, induced spines produced daughters with some induced spine development. In contrast, when females of the basic (non-induced) morph were exposed to Asplanchna kairomone after oviposition of their first egg, some of their second and all of their subsequently oviposited eggs developed into daughters with long spines. In B. calyciflorus and also Keratella tropica , the reproductive cost of Asplanchna -induced defense was determined by comparing population growth rates of basic and Asplanchna -induced morphs. Populations were initiated with individuals of either morph, and Asplanchna was present with the induced morph to assure that all individuals born during the culture period had long spines. In each of three separate experiments with each rotifer species, population growth rates of basic and induced morphs were statistically indistinguishable. Thus, possession of long spines in the absence of Asplanchna is unlikely to inhibit the reproduction of these rotifers through any allocation or energetic cost. Content Type Journal Article Pages 1-12 DOI 10.1007/s10452-012-9416-x Authors John J. Gilbert, Department of Biological Sciences, Dartmouth College, 78 College Street, Hanover, NH 03755, USA Journal Aquatic Ecology Online ISSN 1573-5125 Print ISSN 1386-2588

Description:    Understanding models of networks formation is fundamental to explore the role of the structure in the functioning of the systems they describe, and their ability to respond to change. In this work, we aimed to understand whether and how the modular (or compartmented) structure of a network composed by macroinvertebrates and leaf detritus in six pools of aquatic system was related with the decomposition process. First, we evaluated the relationship between the temporal patterns of leaf detritus colonization and the modular subdivision of the network. Modularity was then related with the clustering of the pools based on convergent traits of leaf detritus consumption and environmental conditions. A significant relationship between the colonization patterns and the distribution of taxa and pools in well-defined modules was found. The modular and clustering subdivision of the pools showed a significant overlap, which revealed the intimate linkage between the structure and functioning of the system. Modularity shapes the functional architecture of the network, by increasing the spatial differences of leaf litter decomposition over time and the diversity of functional traits among detritus feeder. As a consequence, modularity influences the variability of communities’ responses to disturbance, increasing the diversity and robustness of functional processes. Our results have also implications from a conservation point of view, showing the importance of habitat heterogeneity for the robustness of ecosystem functioning, potentially enhancing biodiversity with positive, long-term effect on the whole food web. Content Type Journal Article Pages 1-11 DOI 10.1007/s10452-012-9412-1 Authors Bruno Bellisario, Department of Ecological and Biological Sciences (DEB), University of Viterbo, Largo dell’Università Blocco C Snc, 01100 Viterbo, Italy Fulvio Cerfolli, Department of Ecological and Biological Sciences (DEB), University of Viterbo, Largo dell’Università Blocco C Snc, 01100 Viterbo, Italy Giuseppe Nascetti, Department of Ecological and Biological Sciences (DEB), University of Viterbo, Largo dell’Università Blocco C Snc, 01100 Viterbo, Italy Journal Aquatic Ecology Online ISSN 1573-5125 Print ISSN 1386-2588