Functional community structure of fishes along a fluvial gradient in the Río Grijalva basin, México

Allison A. Pease, Kirk O. Winemiller, Manuel Mendoza-Carranza (ECOSUR, México), Rocio Rodiles-Hernandez (ECOSUR, México), Alfonso Gonzales-Diaz (ECOSUR, México)

The goal of this research is to examine the influence of environmental variables on fish assemblage structure and functional trait diversity along a longitudinal gradient in a large, tropical river basin.  Feeding ecology, habitat association, and functional trait values of fishes will be examined along with a suite of environmental variables in local communities throughout the Río Grijalva basin in southern Mexico.  Community structure and functional trait diversity will be compared across a range of environments, from headwater streams to broad lowland lagoons in the coastal plains.  The most important environmental influences on community structure and trait diversity are expected to be factors related to food resource availability and habitat stability.  Functional trait diversity is predicted to be highest in lowland communities, where habitats are more stable and high productivity and spatial heterogeneity provide for a broad prey resource base.  This diversity is expected to decrease in communities further upstream, where the flow regime is harsher and fewer favorable habitat types are available for fishes or their prey resources.   This project is funded by the National Science Foundation, American Cichlid Association, L.T. Jordan Foudation, and Texas A&M Office of Graduate Studies

Local and regional influences on functional community structure in streams of the Brazos and Trinity basins, Texas

Allison A. Pease, Kirk O. Winemiller, Ryan King (Baylor U.)

As part of a larger project funded by the Texas Commission on Environmental Quality (TCEQ), we examined fishassemblages and habitat quality in streams of theBrazos and Trinity River basins from 2006 to 2008.  The broad aim of this research is to examine how stream fish community structure may be used in combination with detailed environmental measurements to assess stream health in this region.   Our emphasis for this particular study is to investigate how environmental factors at local and regional scales relate to patterns in functional community structure.

Ecology of an introduced cichlid, Archocentrus nigrofasciatus and native Herichthys cichlids in the Río Pánuco basin, México

Allison A. Pease, Gil Rosenthal (Texas A&M, Biology Dept.)   

The convict cichlid, Archocentrus nigrofasciatus, is a popular species in the aquarium hobby, due largely to its hardiness and ease of breeding in captivity.  These traits also increase its chances of establishment when introduced in non-native environments, however, and many established nonindigenous populations have been reported.  A recent introduction of A. nigrofasciatus from an aquarium breeding facility has led to its establishment and spread in the Río Pánuco basin in east-central México.  The ecological effects of this species in Río Pánuco communities have not yet been examined, but there appears to be a decline in the native cichlid species where it is present.  In this study, we will compare resource use of native Herichthys species in communities with and without introduced A. nigrofasciatus in order to examine niche overlap and to test for evidence of niche shifts where they co-occur.  Additionally, we will compare diet and habitat use of A. nigrofasciatus in Río Pánuco communities with data from its native range in Costa Rica.  This project is funded by North American Native Fish Association and logistical support is provided by the CICHAZ research station in Calnali, Hidalgo.

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Updated September 29, 2008