Oil palm crops effects on environmental integrity of Amazonian streams and Heteropteran (Hemiptera) species diversity

Abstract

Climatic and edaphic conditions in the Amazon basin are ideal for the cultivation of the oil palm (Elaeis guineensis Jacq.), this has led to a major expansion in plantations in recent years, to the point where oil palm cultivation has become one of the main threats to biodiversity in this biome. This study aimed to evaluate the effects of oil palm crops on the integrity of freshwater environments and assess the response of aquatic assemblages. A set of 244 environmental metrics were measured at 22 Amazonian streams, either reference sites located in natural forest or oil palm plantation sites. We developed an aquatic environment integrity index for these sites. Biological sampling consisted of the collection of specimens of aquatic and semi-aquatic Heteropteran species. From environmental variables dataset, some were evaluated and five were screened to assess the environments and employed in the streams abiotic integrity index (SAII) to these environments. The SAII proved an excellent for assessing aquatic environments and assaying changes in the freshwater habitats (forest and oil palm) analysed in this study. The forest streams had higher environmental integrity than the plantation streams. Environmental integrity was associated with Heteropteran species richness, although not to abundance of individual species. These results are consistent with previous research on the effects of oil palm crops on aquatic habitats, which showed that the greatest impact was on factors associated with the structure of the riparian zone. These findings should inform development of a strategy to mitigate or minimise the environmental problems caused by ongoing expansion of oil palm plantations in the Amazon basin, in order to safeguard the region's aquatic biodiversity.