Can hydrologic management practices of rice fields contribute to macroinvertebrate conservation in southern Brazil wetlands?

Abstract

The expansion of rice fields is one of the main human activities responsible for the decline of natural wetlands throughout the world. However, rice fields have been recognized as having considerable potential value for many aquatic species. In this sense, an important question from the point of view of biodiversity conservation is the adequacy of these agricultural wetlands as an integrated managed landscape that contributes to maintain a rich biodiversity. The two main questions of this study were: (1) Do richness, density, and composition of macroinvertebrates differ in rice fields with different management practices (flooded and dry)?; and, (2) Do richness, density and composition of macroinvertebrates change in rice fields over the rice cultivating phases? Six collections were carried out in six rice fields with different management practices after cultivation (three dry and three flooded during the fallow phase). The macroinvertebrates were sampled using a corer (7.5-cm diameter) inserted 10 cm into the substratum of the rice fields. We recorded 6,425 macroinvertebrates, comprising 71 macroinvertebrate taxa. Macroinvertebrate richness and density varied over the rice cultivating cycle. The different management practices adopted after cultivation did not influence the macroinvertebrate richness and density; however, they influenced composition. Thus, the mosaic created by the variation of flooded and dry rice fields would provide the setting for a greater number of taxa within the agricultural landscape. The difference in taxa composition between flooded and dry rice fields is an interesting result in terms of biodiversity conservation. Rice producers could maintain part of their agricultural land flooded during the fallow phase. These management practices adopted could be an important strategy for biodiversity conservation in areas where the natural wetlands were converted into rice fields.

Do Hydrologic Regimes Used in Rice Fields Compromise the Viability of Resting Stages of Aquatic Invertebrates?

“…In this phase, the agricultural land is drained and surface water is not present. Since these irrigated rice fields show a high invertebrate diversity (Stenert et al 2009), and the invertebrate resting stages can remain viable over many years in the wetland sediments (Wiggins et al 1980;Boulton and Lloyd 1992;Brock et al 2003;Jenkins and Boulton 2007), the present study tested the hypothesis that the hydrologic regime adopted in rice fields of southern Brazil does not compromise the viability of resting stages of aquatic invertebrates. Furthermore, our study analyzed how richness, density, and composition of drought-resistant aquatic invertebrates respond to experimental rehydration after different periods without surface water in rice fields of southern Brazil.…”

“…On the other hand, irrigated rice fields have been regarded as a refuge for biologic diversity throughout the world (Fernando et al 1979;Bambaradeniya and Amerasinghe 2003;Elphick and Oring 2003), including southern Brazil (Stenert et al 2009;Rolon and Maltchik 2010). However, the potential for recovery of biologic communities via dormant propagule banks has not been investigated in rice field sediments.…”

Waterbird Monitoring in the Antsalova Region, Western Madagascar

“…Rice fields are also used to graze various livestock, ranging from cattle (e.g. in South America; Stenert et al 2009) to ducks (e.g. in China; Muzaffar et al 2010).…”

Cercariae (Digenea: Strigeidae, Diplostomidae) in Biomphalaria straminea (Planorbidae) from a rice field in Northeastern Argentina

“…Worldwide, several studies have demonstrated its importance in biological conservation, since can improve habitats for many species of aquatic invertebrates, as insects, molluscs, crustaceans; and vertebrates, as fish, amphibians, reptiles and birds (Bambaradeniya, 2000;Czech & Parsons, 2002;Bambaradeniya & Amerasinghe, 2003;Manley, 2008; Elphick, Parsins, Fasola, & Mugica, 2010). In the Neotropical region, different studies have been carried out about the biodiversity of macroinvertebrates, amphibians, birds and macrophytes in the irrigated channels of rice fields (Blanco, López-Lanús, Dias, Azpiroz, & Rilla, 2006;Stenert, Bacca, Maltchik, & Rocha, 2009;Machado & Maltchik, 2010;Maltchik, Rolon, Stenert, Machado, & Rocha, 2011). Specifically in Northeastern Argentina, the macroinvertebrates, planorbids, amphibians, fish and birds diversity has been the subject of studies in rice fields Duré, Kehr, Schaefer, & Marangoni, 2008;Blanco & de la Balze, 2011).…”