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6 Native Fishes

Influence of landscape and reach-scale variables on aquatic community structure in tropical island streams. Catherine L. Hein, Andrew S. Pike, J. Felipe Blanco, Todd A. Crowl, Fred N. Scatena, Melinda Laituri, and Alan P. Covich. 6 Native Fishes. Eels. Mullet. Eleotrids. Gobies.

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6 Native Fishes

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  1. Influence of landscape and reach-scale variables on aquaticcommunity structure in tropical island streams Catherine L. Hein, Andrew S. Pike, J. Felipe Blanco, Todd A. Crowl, Fred N. Scatena, Melinda Laituri, and Alan P. Covich

  2. 6 Native Fishes Eels Mullet Eleotrids Gobies

  3. 10 Native Shrimps and 1 River Crab Palaemonid Shrimp Atyid Shrimp

  4. Tropical Island Streams Diadromy Larvae Eggs/Adults Adults Post-larvae

  5. Modeling Complex Interactions of Overlapping River and Road Networks in a Changing Landscape • Overarching hypothesis: An integrated, individual based modeling framework will better predict interactive effects of humans on river landscapes than will individual physical, chemical, biological and social models

  6. Sample Sites Espiritu Santo Mameyes 4 pools/riffles at each of 24 sites

  7. Physical models Social models Biological models Integrated framework Integrated models

  8. What natural and anthropogenic variables at landscape and/or reach-scales determine fish and decapod community structure in two Puerto Rican watersheds? • Distribution of each species (6 fishes and 8 decapods) • Community assemblage

  9. Field Sampling Trapping Snorkeling Electrofishing Sampled 90 pools and associated riffles

  10. Landscape Variables • Largest downstream vertical drop (m) • Elevation • % land cover within a 250 m radius of each site (urban, agriculture, or forest) • Number of downstream road crossings • Road type

  11. Geomorphology • Pool Variables • Length • Width • Variation in width • Maximum depth • Variation in depth • Grain size • Bedrock • Megaboulder • Boulder • Cobble • Gravel • Sand • Fines

  12. Present Absent Agonostomus monticola Anguilla rostrata Gobiomorus dormitor Individual Species Distributions – Waterfalls Vertical Drop > 3.5 m No Yes Atya lanipes Absent Present

  13. Macrobrachium crenulatum Elevation > 100 m No Yes Elevation < 439 m Absent No Yes Absent Present Individual Species Distributions – Elevation Macrobrachium carcinus Elevation < 439 m No Yes Absent Present

  14. Individual Species Distributions – Pool Length Xiphocaris elongata Awaous tajasica Pool length < 23 m Pool length > 28 m No Yes No Yes Absent Present Absent Present

  15. Individual Species Distributions – Grain Size Eleotris pisonis Sicydium plumieri % Fine sediment < 0.004 Median grain size <64 mm No Yes No Yes Absent Present Absent Present

  16. Community Assemblage

  17. Community Assemblage Headwaters Ocean Large circles indicate greater decapod species richness

  18. Conclusions Natural landscape-level barriers are largely responsible for patterns in community structure • Fishes are below waterfalls and most decapods are above

  19. Conclusions Roads, dams, and urban and agricultural land covers do not significantly affect species distributions in these watersheds Why not?

  20. Culverts Bridge piles Narrow squared culvert Large bridge

  21. Why do anthropogenic factors not have an effect on diadromous fauna in the Espίritu Santo and Mameyes watersheds? • Metrics besides presence/absence were not tested (e.g. abundance) • Diadromous fauna are resilient

  22. Why do anthropogenic factors not have an effect on diadromous fauna? • Metrics besides presence/absence were not tested (e.g. abundance) • Diadromous fauna are resilient • Chronic changes to the landscape have not yet occurred

  23. High Head Dams & Exotic Species

  24. Dave Kikkert Ruth Kikkert Maria Ocasio Torres Enrique Marrero Coralys Ortiz Andy Crowl Paul Nicholson Kaua Friola Wyatt Cross Chelse Prather Funded by NSF Acknowledgements

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