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dc.contributor.authorHopkins, Aarekaen_NZ
dc.date.accessioned2006-07-17T16:22:08Z
dc.date.available2007-04-20T16:37:53Z
dc.date.issued2006en_NZ
dc.identifier.citationHopkins, A. (2006). The potential for Charophyte re-establishment in large, shallow, eutrophic lakes with special reference to Lake Waikare, New Zealand. (Thesis, Master of Science (MSc)). The University of Waikato, Hamilton, New Zealand. Retrieved from https://hdl.handle.net/10289/2419en
dc.identifier.urihttps://hdl.handle.net/10289/2419
dc.description.abstractLake Waikare is a large, shallow eutrophic lake devoid of submerged macrophytes. I investigated potential methods for re-establishing submerged macrophytes in the lake. Specifically, I subjected charophyte (Chara corallina) plantlets to two treatments of exposure in the lake (in areas exposed and sheltered from wind) to test for survival and growth under these conditions, and inside and outside fish exclosures to test for growth and survival in the presence of fish. While plantlets grew outside the exclosures in winter, their accumulated biomass over 21 days was less than protected plantlets. In winter, the accumulated biomass was lower outside than inside exclosures (by ~40%) at the sheltered site and was lower outside than inside exclosures (by 43%) at the exposed site. Overall, growth rates in winter were higher at the sheltered site (compared to the exposed site) by ~7%. In summer, charophyte accumulated biomass inside the exclosures increased by 85%, while at the sheltered site accumulated biomass increased by 58%. Outside the exclosures in summer the plantlets were completely removed at both sites. Overall, growth rates where higher at the exposed site than the sheltered site by 31%. Fish were responsible for the partial removal of plantlets in winter and total removal of plantlets in summer, and therefore affect the survival and growth of charophytes in Lake Waikare. The embayment at the sheltered site provides the best location in winter for re-establishment of charophytes from oospores because better growth rates were obtained there, and its sheltered location provides protection from severe wave action found at the exposed site. Oospores did not germinate after being submersed in the lake for 90 days due to heavy sedimentation. To induce an improvement in the present light climate, Alum was tested to determine its effectiveness and longevity for settling lake sediments to allow charophytes to establish and grow. Examining the settling rates of Lake Waikare sediments and water treated with Alum over a range of suspended sediment concentrations and time intervals, sediments settled faster with Alum than without for at least 15 days (at 200 g l^1 suspended sediment concentration) and it remained active to 60 days but at reduced effectiveness. At the other concentrations tested (100 g l^1 and 300 g l^1 suspended sediment concentration), Alum responses were insignificant. An improved light climate achieved by fish removal or Alum treatment will likely not be sufficient to permit the re-establishment of submerged macrophytes due to the turbid, algal-dominated state of the lake. The present nutrient and sediment levels, wave climate and fish influence must be mitigated so charophyte plantlets can be established.en_NZ
dc.format.mimetypeapplication/pdf
dc.language.isoen
dc.publisherThe University of Waikatoen_NZ
dc.rightsAll items in Research Commons are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated.
dc.subjectlake restorationen_NZ
dc.subjectsubmerged macrophytesen_NZ
dc.subjectshallow eutrophic lakesen_NZ
dc.subjectLake Waikareen_NZ
dc.subjectJar testen_NZ
dc.subjectAlumen_NZ
dc.subjectbiomanipulationen_NZ
dc.titleThe potential for Charophyte re-establishment in large, shallow, eutrophic lakes with special reference to Lake Waikare, New Zealand.en_NZ
dc.typeThesisen_NZ
thesis.degree.disciplineScience and Engineeringen_NZ
thesis.degree.grantorUniversity of Waikatoen_NZ
thesis.degree.levelMasters
thesis.degree.nameMaster of Science (MSc)en_NZ
uow.date.accession2006-07-17T16:22:08Zen_NZ
uow.date.available2007-04-20T16:37:53Zen_NZ
uow.identifier.adthttp://adt.waikato.ac.nz/public/adt-uow20060717.162208en_NZ
uow.date.migrated2009-06-09T23:30:20Zen_NZ
pubs.place-of-publicationHamilton, New Zealanden_NZ


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