Search

Proposed hydropower dams at more than 350 sites throughout the Amazon require strategic evaluation of trade-offs between the numerous ecosystem services provided by Earth’s largest and most biodiverse river basin. These services are spatially variable, hence collective impacts of newly built dams depend strongly on their configuration. We use multiobjective optimization to identify portfolios of sites that simultaneously minimize impacts on river flow, river connectivity, sediment transport, fish diversity, and greenhouse gas emissions while achieving energy production goals. We find that uncoordinated, dam-by-dam hydropower expansion has resulted in forgone ecosystem service benefits. Minimizing further damage from hydropower development requires considering diverse environmental impacts across the entire basin, as well as cooperation among Amazonian nations. Our findings offer a transferable model for the evaluation of hydropower expansion in transboundary basins.

Riverine floodplains are biologically diverse and productive ecosystems. Although tropical floodplains remain relatively conserved and ecologically functional compared to those at higher latitudes, they face accelerated hydropower development, climate change, and deforestation. Alterations to the flood pulse could act synergistically with other drivers of change to promote profound ecological state change at a large spatial scale. State change occurs when an ecosystem reaches a critical threshold or tipping point, which leads to an alternative qualitative state for the ecosystem. Visualizing an alternative state for Amazonian floodplains is not straightforward. Yet, it is critical to recognize that changes to the flood pulse could push tropical floodplain ecosystems over a tipping point with cascading adverse effects on biodiversity and ecosystem services. We characterize the Amazonian flood pulse regime, summarize evidence of flood pulse change, assess potential ecological repercussions, and provide a monitoring framework for tracking flood pulse change and detecting biotic responses.

Introduced species can have strong ecological, social and economic effects on their non-native environment. Introductions of megafaunal species are rare and may contribute to rewilding efforts, but they may also have pronounced socio-ecological effects because of their scale of influence. A recent introduction of the hippopotamusHippopotamus amphibiusinto Colombia is a novel introduction of a megaherbivore onto a new continent, and raises questions about the future dynamics of the socio-ecological system into which it has been introduced. Here we synthesize current knowledge about the Colombian hippopotamus population, review the literature on the species to predict potential ecological and socio-economic effects of this introduction, and make recommendations for future study. Hippopotamuses can have high population growth rates (7–11%) and, on the current trajectory, we predict there could be 400–800 individuals in Colombia by 2050. The hippopotamus is an ecosystem engineer that can have profound effects on terrestrial and aquatic environments and could therefore affect the native biodiversity of the Magdalena River basin. Hippopotamuses are also aggressive and may pose a threat to the many inhabitants of the region who rely upon the Magdalena River for their livelihoods, although the species could provide economic benefits through tourism. Further research is needed to quantify the current and future size and distribution of this hippopotamus population and to predict the likely ecological, social and economic effects. This knowledge must be balanced with consideration of social and cultural concerns to develop appropriate management strategies for this novel introduction.

Interdisciplinary Research in Earth Sciences program [NNX14AD29G]; MacArthur Foundation under the Living Andean Rivers initiative [16-1607-151053-CSD]

WOS:000630750300001; 1. The Amazon basin hosts the Earth's highest diversity of freshwater fish. Fish species have adapted to the basin's size and seasonal dynamics by displaying a broad range of migratory behaviour, but they are under increasing threats; however, no study to date has assessed threats and conservation of Amazonian migratory fishes. 2. Here, the available knowledge on the diversity of migratory behaviour in Amazonian fishes is synthesized, including the geographical scales at which they occur, their drivers and timing, and life stage at which they are performed. 3. Migratory fishes are integral components of Amazonian society. They contribute about 93% (range 77-99%) of the fisheries landings in the basin, amounting to -US\436 million annually. 4. These valuable fish populations are mainly threatened by growing trends of overexploitation, deforestation, climate change, and hydroelectric dam development. Most Amazonian migratory fish have key ecological roles as apex predators, ecological engineers, or seed-dispersal species. Reducing their population sizes could induce cascading effects with implications for ecosystem stability and associated services. 5. Conserving Amazonian migratory fishes requires a broad portfolio of research, management, and conservation actions, within an ecosystem-based management framework at the basin scale. This would require trans-frontier coordination and recognition of the crucial importance of freshwater ecosystems and their connectivity. 6. Existing areas where fishing is allowed could be coupled with a chain of freshwater protected areas. Management of commercial and subsistence species also needs fisheries activities to be monitored in the Amazonian cities and in the floodplain communities to allow assessments of the status of target species, and the identification of management units or stocks. Ensuring that existing and future fisheries management rules are effective implies the voluntary participation of fishers, which can be achieved by increasing the effectiveness and coverage of adaptive community-based management schemes.

The Caucasus region is a meeting point for culture and nature, lying at the nexus of Europe, the Middle East, Central Asia, and Africa, and identified as one of 36 global biodiversity hotspots. The Republic of Georgia, the center of the Caucasus biodiversity hotspot, encompasses a geographically diverse landscape inhabited by a remarkable, endemic, and understudied flora and fauna under increasing threat from human activities. A wave of new and proposed dams for hydropower presents one of the most pressing challenges for freshwater biodiversity conservation in Georgia, a country where hydropower accounts for >90% of electricity. However, this situation remains largely unknown to the international scientific community and there is limited scientific information available about Georgia in the internationally indexed peer-reviewed literature. In this article, we describe the geography, politics, and freshwater biodiversity of rivers of Georgia, with a focus on fishes. We examine trends in hydropower development over the past century and identify four distinct periods: the pre-Soviet period (until 1921), the Soviet period (1921–1991), the 1990s immediately following Georgia's declaration of independence, and the 21st century. We explore the effects of existing and proposed dams on the connectivity of rivers of western Georgia and their potential consequences for conservation of diadromous, potamodromous, and resident fish. Using the Dendritic Connectivity Index (DCI) as an analytical lens, we found serial decreases in DCI values following different periods of hydropower development in the country. Finally, we offer four considerations for future research and conservation in light of ongoing hydropower development: i) expand biodiversity research and environmental monitoring, ii) assess and implement environmental flows for Georgian rivers, iii) implement strategic planning for new hydropower development, and iv) establish strict conservation areas for protection of endangered sturgeons.

Incluye contenido parcial de los autores Biological invasion is one of the main threats to native biodiversity. For a speciesto become invasive, it must be voluntarily or involuntarily introduced by humans into a nonna-tive habitat. Mammals were among first taxa to be introduced worldwide for game, meat, and labor, yet the number of species introduced in the Neotropics remains unknown. In this dataset, we make available occurrence and abundance data on mammal species that (1) transposeda geographical barrier and (2) were voluntarily or involuntarily introduced by humans into theNeotropics. Our data set is composed of 73,738 historical and current georeferenced recordson alien mammal species of which around 96% correspond to occurrence data on 77 speciesbelonging to eight orders and 26 families. Data cover 26 continental countries in the Neotrop-ics, ranging from Mexico and its frontier regions (southern Florida and coastal-central Floridain the southeast United States) to Argentina, Paraguay, Chile, and Uruguay, and the 13 coun-tries of Caribbean islands. Our data set also includes neotropical species (e.g.,Callithrixsp.,Myocastor coypus,Nasua nasua)considered alien in particular areas of Neotropics. The mostnumerous species in terms of records are fromBossp. (n=37,782),Sus scrofa(n=6,730), andCanis familiaris(n=10,084); 17 species were represented by only one record (e.g., Syncerus caf-fer, Cervus timorensis, Cervus unicolor, Canis latrans). Primates have the highest number of spe-cies in the data set (n=20 species), partly because of uncertainties regarding taxonomicidentification of the generaCallithrix,which includes the speciesCallithrix aurita, Callithrixflaviceps, Callithrix geoffroyi, Callithrix jacchus, Callithrix kuhlii, Callithrix penicillata, andtheir hybrids. This unique data set will be a valuable source of information on invasion riskassessments, biodiversity redistribution and conservation-related research. There are no copy-right restrictions. Please cite this data paper when using the data in publications. We alsorequest that researchers and teachers inform us on how they are using the data

River flows connect people, places, and other forms of life, inspiring and sustaining diverse cultural beliefs, values, and ways of life. The concept of environmental flows provides a framework for improving understanding of relationships between river flows and people, and for supporting those that are mutually beneficial. Nevertheless, most approaches to determining environmental flows remain grounded in the biophysical sciences. The newly revised Brisbane Declaration and Global Action Agenda on Environmental Flows (2018) represents a new phase in environmental flow science and an opportunity to better consider the co-constitution of river flows, ecosystems, and society, and to more explicitly incorporate these relationships into river management. We synthesize understanding of relationships between people and rivers as conceived under the renewed definition of environmental flows. We present case studies from Honduras, India, Canada, New Zealand, and Australia that illustrate multidisciplinary, collaborative efforts where recognizing and meeting diverse flow needs of human populations was central to establishing environmental flow recommendations. We also review a small body of literature to highlight examples of the diversity and interdependencies of human-flow relationships-such as the linkages between river flow and human well-being, spiritual needs, cultural identity, and sense of place-that are typically overlooked when environmental flows are assessed and negotiated. Finally, we call for scientists and water managers to recognize the diversity of ways of knowing, relating to, and utilizing rivers, and to place this recognition at the center of future environmental flow assessments. This article is categorized under: Water and Life > Conservation, Management, and Awareness Human Water > Water Governance Human Water > Water as Imagined and Represented.

Upstream range shifts of freshwater fishes have been documented in recent years due to ongoing climate change. River fragmentation by dams, presenting physical barriers, can limit the climatically induced spatial redistribution of fishes. Andean freshwater ecosystems in the Neotropical region are expected to be highly affected by these future disturbances. However, proper evaluations are still missing. Combining species distribution models and functional traits of Andean Amazon fishes, coupled with dam locations and climatic projections (2070s), we (a) evaluated the potential impacts of future climate on species ranges, (b) investigated the combined impact of river fragmentation and climate change and (c) tested the relationships between these impacts and species functional traits. Results show that climate change will induce range contraction for most of the Andean Amazon fish species, particularly those inhabiting highlands. Dams are not predicted to greatly limit future range shifts for most species (i.e., the Barrier effect). However, some of these barriers should prevent upstream shifts for a considerable number of species, reducing future potential diversity in some basins. River fragmentation is predicted to act jointly with climate change in promoting a considerable decrease in the probability of species to persist in the long-term because of splitting species ranges in smaller fragments (i.e., the Isolation effect). Benthic and fast-flowing water adapted species with hydrodynamic bodies are significantly associated with severe range contractions from climate change.

Tropical montane rivers (TMR) are born in tropical mountains, descend through montane forests, and feed major rivers, floodplains, and oceans. They are characterized by rapid temperature clines and varied flow disturbance regimes, both of which promote habitat heterogeneity, high biological diversity and endemism, and distinct organisms’ life-history adaptations. Production, transport, and processing of sediments, nutrients, and carbon are key ecosystem processes connecting high-elevation streams with lowland floodplains, in turn influencing soil fertility and biotic productivity downstream. TMR provide key ecosystem services to hundreds of millions of people in tropical nations. In light of existing human-induced disturbances, including climate change, TMR can be used as natural model systems to examine the effects of rapid changes in abiotic drivers and their influence on biodiversity and ecosystem function.

We evaluated progress towards animal biodiversity research in Georgia, a key area in the Caucasus biodiversity hotspot. By reviewing recently (1990-2018) published articles in all areas of animal diversity research, we unmasked the trends in biodiversity inventory, ecological and biogeographical studies, and conservation issues in Georgia. We concluded that species inventory and biodiversity research in Georgia has significantly increased during the last ten years, however the rate and extent of investigation is far from satisfactory. Major gaps remain in all branches of animal diversity research in Georgia, and consequently existing knowledge is inadequate to address modern challenges related to species and ecosystem conservation. We urge local governmental authorities and international scientific societies to support development of stronger research facilities and cultivate interest in biodiversity inventory and research in Georgia as an important step towards maintaining globally important biodiversity in the Caucasus.

Rainwater harvesting (RWH) is increasingly utilized today by populations to alleviate water supply issues, particularly in rural, dry environments. Limited research has considered, simultaneously, the numerous factors that contribute to sustainability – for example, social acceptance, water quality, and maintenance needs – of RWH. This research aimed to improve the understanding of factors influencing the sustainability of rainwater harvesting systems for domestic use (DRWHS) through examination of social, water quality, and technical feasibility components. We conducted 50 household surveys and 17 rainwater quality analyses in San Jose Xacxamayo, a rural, semi-arid community in Puebla, Mexico. Results showed that DRWHS are socially accepted primarily because of the presence of existing local skills and knowledge, as well as critical need for water. Results from most of the water quality parameters measured were within World Health Organization (WHO) guidelines for human consumption, with the exception of pH, total coliform, and heterotrophic plate count, which required water treatment prior to consumption. Technical feasibility was the main barrier to the sustainability of DRWHS; highly seasonal rainfall and small roof sizes (averaging 70 m2) resulted in households unable to meet annual water needs. Increasing roof sizes and providing water treatment could ensure DRWHS sustainability in the studied community.

Rivers continue to be harnessed to meet humanity’s growing demands for electricity, water, and flood control. While the socioecological impacts of river infrastructure projects (RIPs) have been well-documented, methodological approaches to quantify river fragmentation and flow alteration vary widely in spatiotemporal scope, required data, and interpretation. In this review, we first present a framework to visualise the effects of different kinds of RIPs on river fragmentation and flow alteration. We then review available methods to quantify connectivity and flow alteration, along with their data requirements, scale of application, advantages, and disadvantages. Finally, we present decision-making trees to help stakeholders select among these methods based on their objectives, resource availability, and the characteristics of the project(s) being evaluated. Thematic searches of peer-reviewed literature using topic-relevant keywords were conducted on Google Scholar. The bibliography of selected papers was also reviewed, resulting in the selection of 79 publications. Papers that did not define or apply a specific metric were excluded. With respect to fragmentation, we selected papers focused on instream connectivity and excluded those dealing with overland hydrologic connections. For flow alteration, we selected papers that quantified the extent of alteration and excluded those aimed at prescribing environmental flows. The expected hydrological consequences of various RIP types were ‘mapped’ on a conceptual fragmentation-flow alteration plot. We compiled 29 metrics of river fragmentation and 13 metrics to flow alteration, and used these to develop decision-making trees to facilitate method selection. Despite recent advances in metric development, further work is needed to better understand the relationships between and among metrics, assess their ecological significance and spatiotemporal scale of application, and develop more informative methods that can be effectively applied in data-scarce regions. These objectives are especially critical given the growing use of such metrics in basin-wide conservation and development planning.

Payments for Ecosystem Services (PES) programs are used to achieve both ecosystem services and human well-being objectives. PES employs various governance structures, from top-down, national programs to local, community-managed initiatives. We compare the land use, ecosystem services and human well-being impacts of Costa Rica's national PES program with local PES programs in the Bellbird Biological Corridor. We found no difference in well-being between local PES participants and the control group; however, national PES participants had significantly larger properties and incomes than non-participants. Although many of the national PES sites contain large forested areas, the program did not incentivize changes in land use and therefore did not generate additionality. Reforestation activities are widespread in the study area and have generated locally-important ecosystem services; however, these activities cannot be attributed to current local PES due to widespread reforestation within the control group. Nonetheless, participants in local PES have planted a greater diversity of tree species, suggesting reforestation under local PES may have improved ecological benefits. Our findings suggest that while the additional, non-economic benefits of PES in this region are limited, local PES has more effectively engaged with those who are less economically prosperous, and reforestation has improved ecosystem services provisioning.

Assessing spatial variation in hydrologic processes can help to inform freshwater management and advance ecological understanding, yet many areas lack sufficient flow records on which to base classifications. Seeking to address this challenge, we apply concepts developed in data-rich settings to public, global data in order to demonstrate a broadly replicable approach to characterizing hydrologic variation. The proposed approach groups the basins associated with reaches in a river network according to key environmental drivers of hydrologic conditions. This initial study examines Colorado (USA), where long-term streamflow records permit comparison to previously distinguished flow regime types, and the Republic of Ecuador, where data limitations preclude such analysis. The flow regime types assigned to gages in Colorado corresponded reasonably well to the classes distinguished from environmental features. The divisions in Ecuador reflected major known biophysical gradients while also providing a higher resolution supplement to an existing depiction of freshwater ecoregions. Although freshwater policy and management decisions occur amidst uncertainty and imperfect knowledge, this classification framework offers a rigorous and transferrable means to distinguish catchments in data-scarce regions. The maps and attributes of the resulting ecohydrologic classes offer a departure point for additional study and data collection programs such as the placement ofmore » stations in under-monitored classes, and the divisions may serve as a preliminary template with which to structure conservation efforts such as environmental flow assessments.« less

Challenges for policy makers and water managers working on river basins are on the rise as ambitious water infrastructure projects, coupled with the uncertainty of global climate change, alter rivers worldwide. Water security implications of new water infrastructure are particularly complex for transboundary river basins, rivers shared by multiple countries. Three transboundary basins—the Amazon, Mekong, and Nile—demonstrate how similar water security challenges manifest risks and possible solutions differently. Common challenges in the Amazon, Mekong, and Nile basins include dam development, extensive land-use changes, conservation for biodiversity, indigenous and traditional communities’ reliance on river resources, and systemic sensitivity to global climate change. Water security as a theory and a tool allows for researchers to take an interdisciplinary approach toward finding solutions and areas of collaboration for addressing management challenges of water infrastructure. Research scientists have the opportunity to serve as a bridge between the data and analysis using water security tools and the policy and decision makers planning development and management strategies. Though there is a lack of consistent monitoring and baseline data collected on many of the world’s transboundary rivers in transition, coordinated contribution from scientists to local and national partners can fill the capacity gap. Fig. 1. Hydropower Dam in upper Amazon Basin, Ecuador © 2009 Elizabeth Anderson.

Hydropower development in the Andean Amazon has been underestimated and will disrupt connected human and natural systems., Andes-to-Amazon river connectivity controls numerous natural and human systems in the greater Amazon. However, it is being rapidly altered by a wave of new hydropower development, the impacts of which have been previously underestimated. We document 142 dams existing or under construction and 160 proposed dams for rivers draining the Andean headwaters of the Amazon. Existing dams have fragmented the tributary networks of six of eight major Andean Amazon river basins. Proposed dams could result in significant losses in river connectivity in river mainstems of five of eight major systems—the Napo, Marañón, Ucayali, Beni, and Mamoré. With a newly reported 671 freshwater fish species inhabiting the Andean headwaters of the Amazon (>500 m), dams threaten previously unrecognized biodiversity, particularly among endemic and migratory species. Because Andean rivers contribute most of the sediment in the mainstem Amazon, losses in river connectivity translate to drastic alteration of river channel and floodplain geomorphology and associated ecosystem services.

Equatorial rivers of East Africa exhibit unusually complex seasonal and inter-annual flow regimes, and aquatic and adjacent terrestrial organisms have adapted to cope with this flow variability. This study examined the annual flow regime over the past 40 years for three gauging stations on the Mara River in Kenya and Tanzania, which is of international importance because it is the only perennial river traversing the Mara-Serengeti ecoregion. Select environmental flow components were quantified and converted to ecologically relevant hydraulic variables. Vegetation, macroinvertebrates, and fish were collected and identified at target study sites during low and high flows. The results were compared with available knowledge of the life histories and flow sensitivities of the riverine communities to infer flow–ecology relationships. Management implications are discussed, including the need to preserve a dynamic environmental flow regime to protect ecosystems in the region. The results for the Mara may ...

The United Republic of Tanzania (Tanzania) is rich in freshwater resources and biodiversity. In this article, we highlight the importance of Tanzanian rivers and make a case for the conservation of the freshwater and terrestrial species that rely on these rivers. We provide an overview of current knowledge on Tanzanian rivers and discuss progress towards implementation of the National Water Policy (2002) and Water Management Act (2009), two legislative instruments that have motivated environmental flow assessments on at least six major rivers and offer legal backing for river conservation. We examine major challenges that pose significant threats to water security for river ecosystems and humans in Tanzania, among those: (1) human population growth, (2) agricultural expansion, (3) river flow alterations, (4) industrialization, (5) introduced species, and (6) climate change. We conclude by offering recommendations for future river conservation efforts in Tanzania.

The tropical Andes harbor an extraordinarily varied concentration of species in a landscape under increasing pressure from human activities. Conservation of the region's native plants and animals has received considerable international attention, but the focus has been on terrestrial biota. The conservation of freshwater fauna, particularly the conservation of fishes, has not been emphasized. Tropical Andean fishes are among the most understudied vertebrates in the world. We estimate that between 400 and 600 fish species inhabit the diverse aquatic environments in the region. Nearly 40% of these species are endemic. Tropical Andean fishes are vulnerable to ongoing environmental changes related to deforestation, water withdrawals, water pollution, species introductions, and hydropower development. Additionally, their distributions and population dynamics may be affected by hydrologic alterations and warmer water temperatures associated with projected climate change. Presently, at least three species are considered extinct, some populations are endangered, and some species are likely to decline or disappear. The long-term persistence of tropical Andean fishes will depend on greater consideration of freshwater systems in regional conservation initiatives.

In light of the increasing deterioration of groundwater supplies in Rajasthan, India, rainwater harvesting practices in southern Rajasthan were studied to determine the effects of artificially recharged groundwater on the supply and quality of local groundwater. A physical and geochemical investigation utilizing environmental tracers (δ18O and Cl–), groundwater level and groundwater quality measurements, and geological surveys was conducted with two objectives: (1) to quantify the proportion of artificially recharged groundwater in wells located near rainwater harvesting structures and (2) to examine potential effects of artificial recharge on the quality of groundwater in these wells. A geochemical mixing model revealed that the proportion of artificial recharge in these wells ranged from 0 to 75%. Groundwater tracer, water table, and geological data provided evidence of complex groundwater flow and were used to explain the spatial distribution of artificial recharge. Furthermore, wells receiving artificial recharge had improved groundwater quality. Statistical analysis revealed a significant difference between the water quality in these wells and wells determined not to receive artificial recharge, for electrical conductivity and SO 4 – . The findings from this study provide quantitative evidence that rainwater harvesting structures in southern Rajasthan influence the groundwater supply and quality of nearby wells by artificially recharging local groundwater.

1. Costa Rica has recently experienced a rapid proliferation of dams for hydropower on rivers draining its northern Caribbean slope. In the Sarapiqui River Basin, eight hydropower plants were built between 1990 and 1999 and more projects are either under construction or proposed. The majority of these dams are small (

1.Tropical rivers are increasingly being altered by hydropower dams. In Costa Rica, more than 30 hydropower plants were built during the 1990s and more dams are being proposed. Hydropower dams currently provide more than 80% of electricity consumed by the country's 4 million residents, yet most of Costa Rica's hydropower potential remains untapped. 2.Ecological consequences of dams in Costa Rica stem primarily from river fragmentation, stream de-watering, and downstream hydrological alterations. Dams affect distribution and abundance of aquatic biota, especially migratory species. Cumulative effects of multiple dams on individual river basins, especially in the northern part of the country, are also of concern but have not been adequately documented. 3.In light of recent hydropower development, we recommend conservation strategies that protect remaining free-flowing rivers, call for assessment of ecological impacts of dams on a broader scale, encourage research on aquatic systems and sustainable hydropower technologies, and promote the development of methods for estimating environmental flows for Costa Rican rivers. Copyright © 2006 John Wiley & Sons, Ltd.

Small dams for hydropower have caused widespread alteration of Central American rivers, yet much of recent development has gone undocumented by scientists and conservationists. We examined the ecological effects of a small hydropower plant (Dona Julia Hydroelectric Center) on two low-order streams (the Puerto Viejo River and Quebradon stream) draining a mountainous area of Costa Rica. Operation of the Dona Julia plant has dewatered these streams, reducing discharge to ∼10% of average annual flow. This study compared fish assemblage composition and aquatic habitat upstream and downstream of diversion dams on two streams and along a ∼4 km dewatered reach of the Puerto Viejo River in an attempt to evaluate current instream flow recommendations for regulated Costa Rican streams. Our results indicated that fish assemblages directly upstream and downstream of the dam on the third order Puerto Viejo River were dissimilar, suggesting that the small dam (

A major component of environmental sustainability in water resource development is the explicit allocation of water to meet ecosystem needs. This environmental water allocation is commonly referred to as an environmental flow, which is the main subject of this chapter. A shift towards more consideration of water needs of ecosystems/environment in Central and South America has been more irregular, with some countries increasingly articulating and prioritizing these needs (e.g., Costa Rica and Colombia) and others not. The situation is similar in Africa, where ambitious new water policies with substantial attention to environmental protection have appeared in Eastern and Southern Africa (McClain et al., Int J Water Resour Dev 29(4):650–665, 2013) and Asia, where China stands out as a globally important country undergoing rapid change in its outlook towards environmental flows (Wang et al., Ecol Appl 21:163–174, 2009). In this chapter, we explore the status of environmental flow science and practice around the world, focusing on the gap that exists between environmental flow levels suggested by aquatic scientists and those actually protected in water regulations. With a wealth of science and different technologies to make use of, some of the most difficult challenges in applying best environmental flow practices lie in the governance processes and equitable allocation among water users and the environment. This brings us back to the promise of IWRM itself as a process to facilitate integration of these factors in a highly participatory fashion. In this chapter, we have endeavored to summarize the promise and highlight the current challenges of environmental flow assessment and implementation to enable the protection of ecosystems in the process of IWRM.

Recent pieces in Science rightly call for greater examination of the environmental, political, and economic trade-offs of tropical dams. In his Feature news story “Power play on the Nile” (26 February, p. [904][1]), E. Stokstad explores political uncertainties of the Grand Ethiopian Renaissance

The genetic population structures of the landlocked shrimp, Neocaridina denticulata denticulata , and the amphidromous shrimp, Caridina leucosticta , were compared in order to evaluate the effect of dispersal ability on the genetic structure. This chapter examines the mitochondrial DNA (mtDNA) sequence variations of the region extending from the NADH dehydrogenase subunit 2 (ND2) gene to the tryptophan transfer RNA gene and the region encoding NADH dehydrogenase subunit 5 (ND5) gene in 120 specimens of N. d. denticulata from six locations and 160 specimens of C. leucosticta from eight locations. The neighbour joining tree showed several distinct clades roughly corresponding to the local populations within N. d. denticulata , but no distinct clades within C. leucosticta . Pairwise Φ ST and AMOVA also indicated a significantly strong genetic differentiation among local populations of N. d. denticulata , but no or little genetic differentiation among local populations of C. leucosticta . Keywords:amphidromous shrimp; Caridina leucosticta ; mitochondrial DNA; NADH dehydrogenase subunit 2 (ND2); NADH dehydrogenase subunit 5 (ND5); Neocaridina denticulata denticulata ; RNA gene

The tropical Andes harbor an extraordinarily varied concentration of species in a landscape under increasing pressure from human activities. Conservation of the region's native plants and animals has received considerable international attention, but the focus has been on terrestrial biota. The conservation of freshwater fauna, particularly the conservation of fishes, has not been emphasized. Tropical Andean fishes are among the most understudied vertebrates in the world. We estimate that between 400 and 600 fish species inhabit the diverse aquatic environments in the region. Nearly 40% of these species are endemic. Tropical Andean fishes are vulnerable to ongoing environmental changes related to deforestation, water withdrawals, water pollution, species introductions, and hydropower development. Additionally, their distributions and population dynamics may be affected by hydrologic alterations and warmer water temperatures associated with projected climate change. Presently, at least three species are considered extinct, some populations are endangered, and some species are likely to decline or disappear. The long-term persistence of tropical Andean fishes will depend on greater consideration of freshwater systems in regional conservation initiatives.

Iconic ecosystems like the Florida Coastal Everglades can serve as sentinels of environmental change from local to global scales. This characteristic can help inform general theory about how and why ecosystems transform, particularly if distinctive ecosystem properties are studied over long time scales and compared to those of similar ecosystems elsewhere. Here we review the ways in which long-term, comparative, international research has provided perspectives on iconic features of the Everglades that have, in turn, informed general ecosystem paradigms. Studies in other comparable wetlands from the Caribbean to Australia have shed light on distinctive and puzzling aspects such as the “upside-down estuary” and “productivity paradox” for which the Everglades is known. These studies suggest that coastal wetlands on carbonate (karstic) platforms have: (1) hydrological and biogeochemical properties that reflect “hidden” groundwater sources of water and nutrients, (2) very productive, mat-forming algal communities that present a low-quality food to aquatic consumers that encourages (3) highly diversified feeding strategies within and among populations, and (4) extensive and productive seagrass meadows and mangrove forests that promote strong cultural dependencies associated with the ecosystem services they provide. The contribution of international research to each of these general ecological topics is discussed with a particular goal of encouraging informed decision-making in threatened wetlands across the globe.

In his News Focus story “Venturing back into Colombia” (2 August, p. [450][1]), A. Regalado described new opportunities for research and unprecedented threats to biodiversity, as “no-go zones”—particularly the Colombian Amazon—become increasingly stable. As directors of an international