Effects of suspended solids on the establishment and growth of Egeria densa
1993; Elsevier BV; Volume: 45; Issue: 4 Linguagem: Inglês
10.1016/0304-3770(93)90030-z
ISSN1879-1522
AutoresChris C. Tanner, John S. Clayton, Rohan D. S. Wells,
Tópico(s)Marine and coastal plant biology
ResumoTo identify levels of suspended solids (SS) in Lake Waahi (Huntly, New Zealand) favourable for the re-establishment of Egeria densa Planchon, shoots were grown in 2 m deep tanks filled with water transported from the lake and maintained at selected SS loadings between 5 and 40 g m−3 (predominantly compromised kaolinitic clays). Plant growth was measured over periods of 44–47 days in spring, summer and autumn. Highest relative growth rates (RGR) were recorded in summer (maximum 40 mg g−1 daytt-1). Egeria propagules growing from a depth of 1.85 m showed positive growth responses at SS levels up to approximately 25 g m−3 (Kd ≈ 1.75) in spring and autumn, and approximately 35 g m−3 (Kd ≈ 1.95) in summer. At SS levels up to 15 g m−3 (Kd = 1.5 m−1), growth was little affected during summer, while during spring and autumn biomass accumulation was reduced to about 60% and RGR values to about 70% of the maximum seasonal values recorded. Egeria shoots showed maximum elongation at about 10–20 g m−3 SS (Kd = 1.3−1.65). Plant architecture became less branched with increasing SS and the number of roots produced decreased. Implications for the establishment of Egeria in turbid waters are discussed.
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