Effects of Tea Plantations on Stream Invertebrates in a Global Biodiversity Hotspot in Africa

Abstract

Tropical stream ecosystems in montane forest watersheds are important centers of endemism and diversity and provide essential ecosystem services. These habitats are subject to a variety of stressors, including the conversion of adjacent terrestrial habitats from forest to agriculture, but the impacts of these anthropogenic effects are largely unknown because of the paucity of studies in these systems. In montane habitats in the wet tropics, large-scale cultivation of tea is common and can represent an important source of income at local and national scales. However, little is known about how tea cultivation impacts adjacent stream ecosystems. In this study, we examine stream macroinvertebrate assemblages in a biodiversity hotspot the East Usambara Mountains, Tanzania. Specifically, we compare diversity of macroinvertebrate assemblages found on cobbles in stream riffles in watersheds dominated by forest with those surrounded by tea cultivation. We found that streams surrounded by tea were characterized by significantly lower dissolved oxygen and had lower total estimated species richness and number of families. Furthermore, the richness of invertebrate taxa known to be sensitive to anthropogenic disturbance were substantially reduced in tea streams and general assemblage-level analysis shows significant differences in the composition of macroinvertebrate assemblages between tea and forested streams. Our results suggest that tea cultivation may reduce stream habitat quality and biodiversity in the East Usambaras. Further research is needed to evaluate the effects of tea cultivation on streams over longer times scales and to address methods for minimizing negative effects of agriculture on montane stream communities.Abstracts in Portuguese and French are available at http://www.blackwell-synergy.com/loi/btp.

Dragonfly (Odonata) community structure in the Eastern Highlands Biodiversity Hotspot of Zimbabwe: potential threats of land use changes on freshwater invertebrates

“…Our findings and those of other researchers (e.g. Biervliet, Wiśniewski, Daniels, & Vonesh, 2009) suggest that deforestation does not only render habitats unsuitable for the colonization and reproduction for forest specialist species, but also threatens forest freshwater biota.…”

Aquatic insect communities in headwater streams of Ciliwung River watershed, West Java, Indonesia

“…Colzani et al (2013) showed evidence of the harmful effects caused by landscape changes on biodiversity, which suggests that these effects also influence the functional organization of stream insect communities. Also, van Bierviliet et al (2009) reported that species richness and aquatic insect diversity were lower in tea plantation streams than in forest streams in Tanzania. Similarly, taxonomic richness and diversity of aquatic insects were higher in the reference (forest) streams than in agricultural and urban streams as reported in Brazil (Hepp et al 2010) and Malaysia (Shafie et al 2017).…”

Linking physico‐chemical parameters and macroinvertebrates for water quality assessment of Kakamega and the East Usambara montane ecosystems in Kenya

“…Recent reports show that the use of macroinvertebrates to assess water quality has gained increasing acceptance in Sub‐Saharan Africa, including studies examining the downstream effects of tea plantations on water quality (Biervliet et al., 2009), the assessment of the ecological integrity of river ecosystems (Ollis et al., 2006), the assessment of water quality using macroinvertebrates (Tamiru, 2019) and examining trends in nutrient concentrations, land use patterns and the structure of benthic macroinvertebrates (Kilonzo et al., 2014). However, in Kenya and Tanzania, the application of these monitoring tools is rather limited.…”