Ichthyofaunal diversity in the upper Jejuí River watershed in eastern Paraguay

ABSTRACT

The upper Jejuí River is a major tributary of the Paraguay River in eastern Paraguay and is the principal drainage for the Mbaracayú Forest Biosphere Reserve. Despite the international significance of the biosphere reserve and detailed documentation of its terrestrial fauna and flora, the fish fauna in its streams remains relatively unknown, with 48 species previously recorded. We sampled 35 sites within the biosphere reserve over five years (2007–2011) to assess the richness of its ichthyofauna. These surveys yielded a new total of 105 known species for the biosphere reserve, including two newly-recorded orders, Gymnotiformes and Cyprinodontiformes, and 14 newly-recorded families. Fish community composition resembled that of previously-reported fish communities from the Paraguay River drainage, with characiforms and siluriforms comprising the majority of the species (57.1% and 31.4%, respectively). Post hoc analyses showed significantly greater ichthyofaunal diversity at sites within the Mbaracayú Forest Nature Reserve, a core protected forest area within the biosphere reserve, compared to areas outside the nature reserve, suggesting a negative impact from deforestation and land conversion on fish assemblages in these headwater streams. Broad regional deforestation places greater emphasis on important management decisions that will protect current biodiversity.

KEYWORDS:

• Paraguay Freshwater Ecoregion
• Atlantic Forest
• richness
• biodiversity

Acknowledgments

We thank the many University of Dubuque students who assisted with fish surveys. Elizabeth Bainbridge, Gretchen Breitbach, WynLyn (Brunson) McBride, Jonathan Colyer, Elizabeth Dawn, Elizabeth Dunn, Frances (Eggers) Owen, Bridgette Fidder, Mikaela (Tully) Foust, Christine Grannis, Megan (Johnson) Sprague, Kayleen (Keehner) Griep, Mackenzie Kissell, Christopher Kuhle, Arthur Magee, Kevin Mathias, Aaron Matthews, Andrew McDonnell, Matthew O’Brien, Jake O’Rourke, Amy (Stutzman) Satterlee, Benjamin Swan, Nicole Tscharner, and all participated in fish surveys as part of a summer class experience. We also thank the FMB rangers who oversaw the field work at the Mbaracayú Forest Biosphere Reserve: Osvaldo Carrillo, Osvaldo Fernandez, and Silverio Ramirez. Hector Vera Alcaraz provided advice for field work and fish identifications. We are grateful to the National Mississippi River Museum and Aquarium, the University of Dubuque, and Emporia State University’s Faculty Research and Creativity Committee for funding.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

GLZ, LJ, JCM, FRP, and MV initiated this project. All co-authors participated in fish surveys. GLZ, LJ, DRE, JCM, AB, and FRP identified specimens in the field. GLZ and LJ identified specimens in the lab. FR-P, SF, and MV managed logistical support at the Mbaracayú Forest Biosphere Reserve. GLZ and DRE wrote the manuscript. DEK managed the GIS database and developed maps. All co-authors reviewed and approved the manuscript.

Supplemental Material

Supplemental data for this article can be accessed here.

Additional information

Funding

This work was supported by the Emporia State University [2009-01]; University of Dubuque [2007-08.001]; National Mississippi River Museum and Aquarium [2007-01].