Fish assemblages and habitat conditions of oxbow lakes and the main channel of the middle-lower Brazos River, a meandering lowland river in east central Texas, were investigated during summer 1994. All oxbows were eutrophic, with chlorophyll-a levels of up to 640 g/L. Assemblage structure showed large between-lake variation that was explained by both physical and biotic variables, with combinations of water depth, dissolved oxygen, dissolved nutrients, turbidity, and plankton densities accounting for 45-59% of the variation in abundance of the dominant species. Water depth and dissolved nutrient concentrations were the best predictors of species diversity and fish abundance. Periodic desiccation of shallow, vegetated oxbows created harsh conditions that favored small fishes that are efficient colonizers. The two youngest oxbows were relatively deep and contained a high diversity and biomass of fishes. Of the 42 fish species collected, several were largely restricted to oxbow lakes, and others were either entirely restricted to or common only in the river channel. The flood dynamics of Brazos River floodplain habitats are less predictable (both intra-and interannually) than are those of large temperate rivers that receive runoff from snowmelt or predictable spring rainfall. As a result, Brazos River oxbow lakes remain separated from the river channel for many months or years, such that faunal exchange between oxbows to the channel should be pulselike and irregular.

Three oxbow lakes with different connection frequencies and an adjacent reach of the middle Brazos River, Texas, were surveyed quarterly from summer 1993 to summer 1996 to examine the effects of hydrology and physicochemical attributes on fish assemblage structure. During flood events, oxbows usually were colonized by about 20 fish species from the river channel, and several fluvial specialists were rarely or never sampled from oxbows. Multivariate analyses of seine samples revealed divergent patterns of assemblage structure during periods of isolation that also were associated with a gradient of maximum water depth, temperature, and conductivity. In contrast, analysis of gill-net samples that targeted large fishes revealed low between-site and temporal variation in assemblage structure among oxbow lakes but significant differences in the structure of oxbow versus channel assemblages. The shallowest oxbow (which dried out with greatest frequency) had the most variable fish assemblage across seasons and was dominated by small colonizing species, whereas deeper oxbows and the river channel tended to have higher species richness and more stable assemblages. Despite large differences in connection frequency and distance from the river channel, the deepest oxbows had the most similar fish assemblage structure across all seasons. Multiple regression analysis suggested that the timing and frequency of flood events (yielding colonization) in the most frequently connected oxbow interact with predator abundance (yielding mortality) to influence the abundance of common lotic-adapted minnows (red shiner Cyprinella lutrensis and bullhead minnow Pimephales vigilax) that periodically dominated the species assemblage of that oxbow after floods. Our results suggest that current hydrologic and geomorphologic dynamics in the middle Brazos River produce oxbow lakes with a range of physical characteristics yielding different disturbance and colonization regimes that strongly influence fish species assemblages.

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The Sustainability is the intent to provide the best outcomes for the human and natural environments both now and indefinite future. The Sustainability relates to the continuity of economic, social, institutional and environmental aspects of human society, as well as the nonhuman environment. The Cosmos Foundation, a non-profit educational organization with 19 campuses and more than 7000 students all over the Texas took an initiative tour toward global awareness. The Cosmos foundation organizes an annual transformative International Science Fair Olympiad called I-SWEEEP (International Sustainable World Energy Engineering & Environment Project Olympiad) since 2008. The Cosmos Foundation brings the best and brightest students from all over the world to Houston, Texas to demonstrate their selected research findings. This paper describes how this Olympiad engages young minds in a search for solutions to the environmental and energy related challenges of today in hopes of achieving a sustainable world for tomorrow. The I-SWEEEP stimulates students' interest in practical solutions and cultivates the future of the energy frontier through unique projects. The mission of I-SWEEEP is to create a collaborative yet competitive environment in which students can present their innovative ideas/projects to solve today's challenges in energy, engineering, and environment, which will ensure a sustainable world for tomorrow. All the judges for the project evaluations are selected from academia and industrial professionals. The judging process gives a good opportunity to engineering professionals and academicians to review and evaluate what prospective engineers have developed for a sustainable future. The I-SWEEEP promotes engineering inventions and energy efficiency/management discoveries, which nurture ecofriendly technology concepts in K-12 STEM education.