Elizabeth P. Anderson

Comparing flow regime, channel hydraulics, and biological communities to infer flow–ecology relationships in the Mara River of Kenya and Tanzania

Abstract 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 serve as a useful model for river basins of the wider equatorial East Africa region. Editor Z.W. Kundzewicz; Guest editor M. Acreman Citation McClain, M.E., Subalusky, A.L., Anderson, E.P., Dessu, S.B., Melesse, A.M., Ndomba, P.M., Mtamba, J.O.D., Tamatamah, R.A., and Mligo, C., 2014. Comparing flow regime, channel hydraulics and biological communities to infer flow–ecology relationships in the Mara River of Kenya and Tanzania. Hydrological Sciences Journal, 59 (3–4), 801–819.

Fragmentation of Andes-to-Amazon connectivity by hydropower dams

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.

Cultural costs of tropical dams

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 Gap Between Best Practice and Actual Practice in the Allocation of Environmental Flows in Integrated Water Resources Management

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.

New perspectives on an iconic landscape from comparative international long-term ecological research

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.

Returning to the Colombian Amazon

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