Spread and status of seven submerged pest plants in New Zealand lakes |
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Authors: | Mary D deWinton Paul D Champion John S Clayton Rohan DS Wells |
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Institution: | 1. National Institute of Water and Atmospheric Research Limited , Hamilton, P.O. Box 11115, New Zealand E-mail: m.dewinton@niwa.co.nz;2. National Institute of Water and Atmospheric Research Limited , Hamilton, P.O. Box 11115, New Zealand |
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Abstract: | The distribution of seven submerged aquatic pest plants is reported. Lake vegetation surveys recorded pest plants in 27.9% of 344 lakes, with two species co‐occurring in 5.8%, and three species in 2.6% of lakes. Egeria densa was most frequent (15.4% of lakes), followed by Ceratophyllum demersum (9.0%), Lagarosiphon major (7.3%), and Utricularia gibba (5.5%). Spread since 2000 has continued for five pest plants, with 34 lakes invaded by U. gibba over 2004–08 alone. Early regional sites in proximity to human population centres were likely plant liberations and numerous potential founder colonies remain in garden ponds. Human activities were important for inter‐lake dispersal, with the exception of bird‐dispersed U. gibba. Significant lake associations between pest plants, and with presence of six exotic fish species, suggest common dispersal pathways and similar introduction risks. Therefore, predictions of future spread should be possible based on sources, dispersal pathways, and identifying key risk factors for lakes. |
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Keywords: | Hydrilla verticillata Ceratophyllum demersum Egeria densa Lagarosiphon major Utricularia gibba Vallisneria gigantea Vallisneria spiralis lakes distribution dispersal spread |
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