Aquatic macroinvertebrate community colonisation and succession in macadamia orchard and communal area reservoirs: a case study of Luvuvhu River valley, South Africa

Authors

  • Thendo Mutshekwa 1. Aquatic Systems Research Group, Department of Geography and Environmental Sciences, University of Venda, Thohoyandou 0950, South Africa; 2. Department of Freshwater Invertebrates, Albany Museum, Makhanda 6139, South Africa
  • Lutendo Mugwedi Aquatic Systems Research Group, Department of Geography and Environmental Sciences, University of Venda, Thohoyandou 0950, South Africa
  • Ryan J Wasserman 1. Department of Zoology and Entomology, Rhodes University, Makhanda 6140, South Africa; 2. School of Science, Monash University Malaysia, Bandar Sunway, Selangor Darul Ehsan, Malaysia; 3. South African Institute for Aquatic Biodiversity, Makhanda 6140, South Africa
  • Farai Dondofema Aquatic Systems Research Group, Department of Geography and Environmental Sciences, University of Venda, Thohoyandou 0950, South Africa
  • Ross Cuthbert 1. South African Institute for Aquatic Biodiversity, Makhanda 6140, South Africa; 2. School of Biological Sciences, Queen’s University Belfast, BT9 5DL, Belfast, Northern Ireland
  • Tatenda Dalu 1. South African Institute for Aquatic Biodiversity, Makhanda 6140, South Africa; 2. School of Biology and Environmental Sciences, University of Mpumalanga, Nelspruit 1200, South Africa

DOI:

https://doi.org/10.17159/wsa/2024.v50.i2.4083

Keywords:

agricultural activities, environmental stressors, primary succession, stone substrates

Abstract

The demand for macadamia nut production worldwide has led to increased use of pesticides and chemicals for pest and disease control. Reservoirs in these macadamia farming sectors are at . The current study investigated macroinvertebrate colonisation and succession associated with two macadamia orchards and two communal area reservoirs.  The potential effects of stressors from these land uses was tested for and compared using stone substrates over a 6-week period. Stone substrates from both reservoir types were abundantly colonised over time and the total macroinvertebrate taxa and abundance showed an increasing trend across the sampled weeks, with macadamia orchards having the highest number of macroinvertebrate taxa. Strong ecological succession was observed across reservoirs, with the initial succession of early colonisers – i.e., Chironominae (, Ostracoda (and Anax sp. (predator) within communal area reservoirs, and Chironominae, Ostracoda Radix natalensis (scrapers) in macadamia orchard reservoirs – followed by predatory colonisers such as Gyrinidae larvae, Trithemis sp. (macadamia orchard reservoirs), and Ranatra sp. (communal area reservoirs). Macroinvertebrate community structure differed significantly across sites and weeks, with no similarity being observed for communities across the different reservoirs. Redundancy analyses further highlighted 11 sediment chemistry variables (i.e., pH, resistivity, P, K, Na, Ca, Mg, Cu, B, Fe and S) which were significantly related to macroinvertebrate community structure. Thus, sediment variables were found to be better predictors of macroinvertebrate community structure in macadamia orchard reservoirs than communal area reservoirs. Consequently, we concluded that differences in colonisation ability among taxa and environmental stressors were important factors driving succession. These results add to the understanding of the macroinvertebrate colonisation processes and environmental stressors within agricultural landscapes, which can aid in the development of conservation management of freshwater ecosystems.

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Published

2024-04-30

How to Cite

Thendo Mutshekwa, Lutendo Mugwedi, Ryan J Wasserman, Farai Dondofema, Ross Cuthbert, & Tatenda Dalu. (2024). Aquatic macroinvertebrate community colonisation and succession in macadamia orchard and communal area reservoirs: a case study of Luvuvhu River valley, South Africa. Water SA, 50(2 April). https://doi.org/10.17159/wsa/2024.v50.i2.4083

Issue

Section

Research paper