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Fig. 15.4 Fragments of Caulerpa taxifolia . ( a ) New growth from a field-collected fragment.
( b ) New growth from laboratory trials
and new rhizomes from which new blades emerge. Much more robust than
C. verticillata or C. prolifera , Smith and Walters (1999) found that native Hawaiian
C. taxifolia fragments as small as 1 cm survived and produced new attachment
rhizoids and rhizomes. To compare this to the success of native and invasive
C. taxifolia from Australia, similar laboratory bioassays were run with invasive
Lake Conjola and native Moreton Bay, Australia populations (L. Walters, P. Sacks,
A. Davis and D. Burfiend, unpublished data). For both Australian populations, we
found that blade fragments as small as 4 mm were successful and new growth was
visible within 2-3 days. At 20-mm length, 100% of the blade fragments from
Hawaii and both Australian populations survived and grew (Smith and Walters
1999; L. Walters, P. Sacks, A. Davis and D. Burfiend, unpublished data). Stolon-
only fragments from Australia were only successful if they were at least 15 (Lake
Conjola) or 20 mm in length (Moreton Bay) (L. Walters, P. Sacks, A. Davis and
D. Burfiend, unpublished data). A small percentage of Hawaiian C. taxifolia sto-
lons (10, 15, and 20-mm length) also survived (20%), but none attached (Smith and
Walters 1999). For both Hawaiian and Australian C. taxifolia , new growth occurred
at the wound sites, undamaged growing edges, and along branchlets. Unsuccessful
fragments were obvious because all cytoplasm oozed out within 1 min and only the
colorless cell walls remained. Finally, Smith and Walters (1999) determined the
forces required to create fragments of C. taxifolia using a puncturometer (Pennings
and Paul 1992). Forces needed were significantly less for fronds than that for sto-
lons (Smith and Walters 1999).
15.3.2
Survival of Fragments in Field
Both storms and herbivory naturally create fragments, and these fragments add to
fragmentation associated with recreational and commercial use of the waterways.
Although normally negatively buoyant, fragments may float if covered with mucus
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