Limited plankton community shifts over winter inundation events in Austral temporary wetlands

ABSTRACT

Plankton are key components of wetland ecosystems, comprising different food web levels. In the present study, we assessed temporal plankton diversity patterns in three temporary wetland systems over winter inundation periods. We examined taxon relationships with environmental variability associated with wetland inundation phase changes, over six consecutive sampling events (i.e. T1–T6; or until the ponds dried). Fifty-nine phytoplankton species belonging to 36 genera were identified across the three wetlands, with 21, 22 and 19 taxa being identified for Wetlands 1, 2 and 3, respectively. Twenty-five zooplankton taxa were also identified across the three wetlands. Significant differences in environmental variables were found across sampling events. Ammonium, conductivity, dissolved oxygen, water temperature, turbidity, nitrates (NO₃–N) and zooplankton abundances were identified as important variables structuring phytoplankton communities, whereas, NO₃–N, phosphates and chlorophyll-a concentration were identified as important environmental variables for zooplankton. No significant differences were, however, observed in plankton community structure over time or among wetlands. Accordingly, hydroperiod phases did not have any significant influence on the plankton taxa richness in this study, in contrast to other seasons in the region and other parts of the world. The present study highlights that where temporary wetlands are characterised by both summer and winter inundation events, community succession dynamics may be seasonally distinct and require sampling in both periods to fully understand propagule and emergent community dynamics.

KEYWORDS:

• phytoplankton
• zooplankton
• hydroperiod
• wetland
• chlorophyll-a

Disclosure statement

No potential conflict of interest was reported by the author(s).

Permitting and ethics approval

Samples were collected under permit number CRO 43/16CR, issued by the Department of Economic Development, Environmental Affairs and Tourism. No ethical approval was required since research involved planktonic organisms only.

Data availability statement

The datasets generated and/or analysed during the current study are publicly available in the supplementary files.

Additional information

Funding

This study was funded by the Rhodes University Dean of Science Discretionary Grant. TD and RNC acknowledge support from the Wissenshaftskolleg zu Berlin Institute for Advanced Study/Stellenbosch Institute for Advanced Study and the Alexander von Humboldt Foundation, respectively.

Notes on contributors

Tatenda Dalu

Dr Tatenda Dalu is Lecturer in Water Management at the University of Mpumalanga, South Africa, an Iso Lomso and TWAS Young Affiliate Fellow and Honorary Research Associate at the South African Institute for Aquatic Biodiversity.

Ross N. Cuthbert

Dr Ross N. Cuthbert is Leverhulme Early Career Fellow specialising in aquatic ecoology at Queen’s University Belfast and Honorary Research Associate at the South African Institute for Aquatic Biodiversity.

Ryan J. Wasserman

Prof Ryan J. Wasserman is an Associate Professor of aquatic ecology at Rhodes University,Honorary Research Associate at the South African Institute for Aquatic Biodiversity and Adjunct Research Fellow at Monash University Malaysia.