Amy M. Villamagna

Behavioral Response of American Coots (Fulica americana) to Water Hyacinth (Eichhornia crassipes) in Lake Chapala, Mexico

Abstract. American Coot (Fulica americana) behavior was observed and Water Hyacinth (Eichhornia crassipes) cover measured at Lake Chapala, Mexico, to determine whether site selection, habitat use, behavior within habitat types and selection of habitats for foraging were affected by the invasive aquatic plant. Water Hyacinth significantly affected habitat choice within selected sites but not site selection by coots. Coots spent less time in shallow water and more time in Water Hyacinth as site-level hyacinth cover increased. Water Hyacinth did not restrict coot movement and birds foraged significantly more in patch Water Hyacinth (28.7 ± 2.3% of total time) than in open water (9.8 ± 0.9%). Moreover, coots spent less time foraging in shallow water and more time foraging in hyacinths as cover increased. Coots used Water Hyacinth opportunistically and may have preferred it over other available habitat types. The positive relationships between Water Hyacinth and coots were likely attributed to the introduction of forage and refuge opportunities that were unavailable in Lake Chapala prior to Water Hyacinth invasion. Results suggest that efforts to control Water Hyacinth may indirectly affect the American Coot population.

Community-Level Waterbird Responses to Water Hyacinth (Eichhornia crassipes)

Water hyacinth is among the most widespread invasive plants worldwide; however, its effects on waterbirds are largely undocumented. We monitored site use by waterbirds at Lake Chapala, the largest lake in Mexico and recently designated Ramsar site, to evaluate the potential influence of water hyacinth cover on species composition and aggregate measures of the waterbird community, including waterbird density, species richness, and Simpsons index of diversity. We examined the response of waterbirds to changes in percent water hyacinth cover at 22 independent sites around the lake during six study seasons from May 2006 to February 2008. We found little evidence to suggest that percent water hyacinth cover affected aggregate community measures; however, multivariate analysis of relative species composition suggested that water hyacinth cover corresponded with seasonal species composition (Canonical Correspondence r  =  0.66, P  =  0.007) when seasonal site cover averaged 17.7 ± 4.67% (winter 2007). Several migratory species were not observed during this season, which could suggest that some small-bodied migratory species avoided Lake Chapala during the winter of high water hyacinth cover. We suspect that observed changes in the waterbird community are in response to species-specific tolerances for water hyacinth and indirect abiotic and biotic effects of its presence (e.g., invertebrate and fish composition). Nomenclature: Glyphosate, water hyacinth, Eichhornia crassipes (Mart.) Solms. Management Implications: Water hyacinth is among the most widespread aquatic invasive plants in the world. Yet despite its global recognition, our understanding of how nonnative ecosystems and animal communities, specifically waterbirds, respond to the establishment of this species is relatively weak, which hinders our ability to choose the best potential management strategy. The waterbird community comprises herbivores as well as secondary and tertiary consumers; therefore, changes in community composition and abundance can greatly affect food web structure and energy flows within an affected ecosystem. In addition to their ecological role, waterbirds are the source of cultural and economic values in many regions. A shift in waterbird community composition resulting from water hyacinth establishment has the potential to enhance or reduce socioeconomic values associated with freshwater ecosystems. By understanding how waterbirds respond to water hyacinth, field practitioners (e.g., researchers, managers, and decision-makers) will be better informed when developing research and management priorities. Our results suggest that water hyacinth cover had little effect on aggregate measures of the waterbird community at Lake Chapala, including waterbird density, species richness, and diversity (Simpsons index of diversity), but that some small-bodied, migratory species might avoid sites and/or entire ecosystems with water hyacinth. Although the decision to control water hyacinth and other invasive plants is surely based on a wide assortment of socioeconomic objectives and desired benefits (i.e., protection of municipal water supply), we believe that the ecological response to nonnative plants and potential control methods should be evaluated. Our results suggest a benign relationship between water hyacinth and waterbirds, with the potential exception of some small-bodied, migratory species. Understanding the waterbird response to water hyacinth provides critical pieces in the ecological and socioeconomic puzzle of invasive plant science and management and can help managers evaluate the benefits and costs of control more holistically.

Inequity in ecosystem service delivery: Socioeconomic gaps in the public-private conservation network

Conservation areas, both public and private, are critical tools to protect biodiversity and deliver important ecosystem services (ES) to society. Although societal benefits from such ES are increasingly used to promote public support of conservation, the number of beneficiaries, their identity, and the magnitude of benefits are largely unknown for the vast majority of conservation areas in the United States public-private conservation network. The location of conservation areas in relation to people strongly influences the direction and magnitude of ES flows as well as the identity of beneficiaries. We analyzed benefit zones, the areas to which selected ES could be conveyed to beneficiaries, to assess who benefits from a typical conservation network. Better knowledge of ES flows and beneficiaries will help land conservationists make a stronger case for the broad collateral benefits of conservation and help to address issues of social-environmental justice. To evaluate who benefits the most from the current public-private conservation network, we delineated the benefit zones for local ES (within 16 km) that are conveyed along hydrological paths from public (federal and state) and private (easements) conservation lands in the states of North Carolina and Virginia, USA. We also discuss the challenges and demonstrate an approach for delineating nonhydrological benefits that are passively conveyed to beneficiaries. We mapped and compared the geographic distribution of benefit zones within and among conservation area types. We further compared beneficiary demographics across benefit zones of the conservation area types and found that hydrological benefit zones of federal protected areas encompass disproportionately fewer minority beneficiaries compared to statewide demographic patterns. In contrast, benefit zones of state protected areas and private easements encompassed a much greater proportion of minority beneficiaries (~22–25%). Benefit zones associated with private conservation lands included beneficiaries of significantly greater household income than benefit zones of other types of conservation areas. Our analysis of ES flows revealed significant socioeconomic gaps in how the current public-private conservation network benefits the public. These gaps warrant consideration in regional conservation plans and suggest that private conservation initiatives may be best suited for responding to the equity challenge. Enhancing the ecosystem benefits and the equity of benefit delivery from private conservation networks could build public and political support for long-term conservation strategies and ultimately enhance conservation efficacy.

A New Modeling Approach To Prioritize Riparian Restoration To Reduce Sediment Loading in Two Virginia River Basins

Human impact, particularly land cover changes (e.g., agriculture, construction) increase erosion and sediment loading into streams. Benthic species are negatively affected by silt deposition that coats and embeds stream substrate. Given that riparian buffers are effective sediment filters, riparian restoration is increasingly implemented by conservation groups to protect stream habitats. Limited funding and a multitude of impaired streams warrant the need for cost-effective prioritization of potential restoration actions. We created a decision-support framework for conservation agencies and aquatic resource managers to prioritize riparian restoration efforts. Our framework integrates GIS data and field surveys into a statistical model to predict instream silt from estimates of upland soil loss and riparian filtration capacity. We focus specifically on prioritizing sites in upper sections of the Roanoke and Nottoway river basins (Virginia, US) based on observed records of Roanoke logperch (Percina rex), an imperiled sediment-sensitive species. Our statistical approach examines soil characteristics, land cover, precipitation, topography, and annual soil loss estimates from the empirically derived Revised Universal Soil Loss Equation, combined with land cover-based riparian filtration capacity as potential stream habitat predictors. We found riparian filtration capacity to be a significant predictor of silt cover, while precipitation was a significant predictor of embeddedness. Spatial scale was also a factor, in that spatial variance in silt cover and embeddedness was more accurately predicted at smaller spatial extents. Ultimately, our model can be used as a prioritization tool for mitigating high siltation areas, or for protecting low soil erosion areas.