Ecology of standing waters
Influence of lake-level fluctuation and salinity on food web structure in a coastal brackish lake: Lake Ellesmere/Te Waihora
|
Large coastal brackish lakes are rare ecosystems internationally, and the mixing of both freshwater and saline water inflows can support unusual combinations of floral and faunal communities. Te Waihora / Lake Ellesmere is a highly valued large shallow brackish lake (Waihora Ellesmere Trust), southwest of Banks Peninsula, in Canterbury, New Zealand. Te Waihora is one of Canterbury’s most treasured biodiversity sites, has historically been a major resource for eel and flounder fisheries, has important cultural and recreational values and is recognised as one of New Zealand’s most important wetland systems. In recent years Te Waihora has received much attention due to its declining water quality, hyper-trophic status and declining commercial and customary fisheries (NZ Herald article). |
Historically, the lake covered a larger area and was markedly deeper. In this natural state the lake opened to sea when freshwater pressure was sufficient to breach the gravel barrier at the outlet. Subsequent human modification of the lake level has resulted in manual lake openings being required. Although a number of studies have been conducted on aspects of the ecology of the lake, relatively little is known about the impacts that lake level fluctuation and salinity have on the food web structure.
As part of her MSc research, Taryn Wilks will investigate how lake level fluctuation (either manually lowered or wind driven) and varying salinity concentrations (through sea water intrusion) impact community composition in the littoral zone of Te Waihora, while providing a quantitative assessment of the invertebrate and fish species in the lake. This research will provide further understanding and insight into food web dynamics and structure of a much loved shallow brackish lake in Canterbury.
People involved in this project
University of Canterbury
Taryn Wilks (MSc student)
Jon Harding
Environment Canterbury
Shirley Hayward
Department of Conservation
Dave Kelly
National Institute of Water & Atmospheric Research (NIWA)
Don Jellyman