A decade later: the effects of land use changes in biodiversity patterns of stream fish assemblages from a tropical agroecosystem

Author(s)

Jaquelini de Oliveira Zeni

• Document type: Doctoral Thesis
• Press: São José do Rio Preto. 2017-06-02.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Biociências Letras e Ciências Exatas. São José do Rio Preto
• Defense date: 2017-04-28
• Advisor: Lilian Casatti; David J Hoeinghaus

Abstract

Environmental changes associated with conversion of native vegetation to agroecosystems are considered a powerful drive of fish fauna homogenization in the Anthropocene. Thus, it is essential to understand how subsequent alterations to already altered ecosystems may further affect assemblages. To evaluate whether and how further environmental changes at regional (watershed) and local (instream habitat and ecotone) scales can influence taxonomic and functional fish structure and spatial-temporal beta diversity in agroecosystem streams. Thirty-eight agroecosystem streams were sampled 10 years apart (2003 and 2013). We quantified the degree of regional and local changes and correlated with the degree biological changes (taxonomic and functional structure) and with the spatial-temporal beta diversity between the two periods. The degree of environmental changes at regional and local scales were not correlated with the degree of taxonomic and functional structure changes or spatial-temporal beta diversity. Spatial beta diversity remained unchanged over time and temporal beta diversity was lower than expected by chance. We believe our results indicate that current patterns of fish assemblages in agroecosystem could be widely associated with the past deforestation and the environmental filtering. Probably, past environmental filters were responsible for the selection of habitat generalist species able to adapt and resist several types of environmental changes. Despite no pre-deforestation inventory in the region, most of our fish species are common and regionally distributed, while few rare species are restricted to few streams. In this context, it is possible that the degree of environmental changes observed in this study were not strong enough to cause further changes in fish fauna aspects. Moreover, we detected some evidence for a time lag response or legacy effects. Thus, the effects of rapid conversion of the landscape on instream habitat and biodiversity are presumably not yet fully evident. Unfortunately, this is happening in numerous aquatic systems, and immediate measures that effectively restore streams assemblages should be a priority. (AU)

• FAPESP's process: 12/20280-5 - Landscape changes in medium term: consequences for the composition, trophic structure and functional diversity of fish fauna in tropical streams.
• Grantee: Jaquelini de Oliveira Zeni
• Support Opportunities: Scholarships in Brazil - Doctorate