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| November 2002 |
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Summer on the way: it's sea lettuce time
Administrative work over the winter means the City Council is
ready to deal with sea lettuce build-up in the estuary this summer. In warm conditions the plant can increase its mass by up to 35
per cent a day so it is fortunate that conditions are rarely ideal. Last
summer more than 600 tonnes was collected along the Southshore
foreshore and taken to the landfill. A similar or greater amount is
expected to be removed this summer. Over the winter the Council has gained Environment Canterbury
(ECan) permission to try small-scale removal and control trials at
nine sites, including McCormacks Bay, within the Estuary. It also
sought, and got, permission to keep removing sea lettuce buildups
along Southshore. The Council has a three-year consent to try a range of waterborne
and shore-based manual and mechanical methods.The first in
a series of small-scale trials began this month and public notification
has been given. ECan says the Southshore removal operations can continue for
another five years, using tractor-mounted rakes, loader and truck and
the number of days a year the crews can work has been increased
from three to six. As well, the area was extended slightly to include
the foreshore from Tern Street north to the south end of Estuary
Road. A programme to regularly monitor sea lettuce growth and
accumulation at 17 sites around the estuary has recommenced.
Remote monitoring using satellite imagery and colour and infrared
aerial photography is also being investigated. |