1,721,141 research outputs found
Dispersal of Caulerpa racemosa fragments in the Mediterranean: lack of detachment time effect on establishment
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Nutrient availability in the sediment and the reciprocal effects between the native seagrass Cymodocea nodosa and the introduced rhizophytic alga Caulerpa taxifolia
No full textTwo reciprocal experiments testing for the effects of nutrient addition in the sediment and competitive interactions between the native seagrass Cymodocea nodosa (Ucria) Ascherson and the introduced alga Caulerpa taxifolia (Vahl) C. Agardh were performed. This study was conducted for 13 months (August 1995 until September 1996) in a bay on the south coast of Elba Island (Italy). Each experiment consisted of the manipulation of the level of nutrients (addition vs. control) and the manipulation of the neighbours (presence vs. removal). Response variables were blade density and size for one experiment and shoot density and leaf length of seagrass in the other. Results indicated that the presence of Caulerpa taxifolia did not affect significantly Cymodocea nodosa shoot density and the increased nutrient availability in the sediment did not alter this pattern. Neither the removal of the canopy of the seagrass nor the fertilization of the sediment has influenced significantly the density of the alga. Both species, where co-occurring, show larger size than where the neighbour is removed. Hence, results of this study suggest that the two species on the long term are likely to coexist and that the high nutrient supply of the sediment would not enhance the probability of success neither of the seagrass nor of the alga. Predictions made on the basis of short-term results, that high nutrient loads of the substratum would have represented an even more suitable condition for C. taxifolia to colonize C. nodosa beds and that on the long-term the alga has a high probability of success, did not occur
The Role of vegetative fragmentation in dispersal of the invasive alga Caulerpa taxifolia in the Mediterranean
Full text linkThis study evaluated the importance of fragmentation in the recruitment of the fast-spreading, introduced green alga Caulerpa taxifolia at the margins of beds of the seagrass Posidonia oceanica. A multifactorial experiment was designed to test the hypotheses that there are seasonal differences in patterns of establishment of vegetative fragments, whether this process changes with depth and whether these patterns were consistent at different spatial and temporal scales. Our experimental approach consisted of dispersing drifting fragments of C. taxifolia along the margin of a bed of P. oceanica and recording the number of fragments established after 1 mo. The results show that a surprisingly large number of fragments become established in this habitat and that numbers varied in space and time: the probability of establishment of fragments was greatest during summer especially at the shallow sites, but smaller in spring and smallest in winter. Differences among areas were also found: a great variability in establishment of fragments depended on the site and time within season. Results indicate that dispersal by fragmentation can greatly contribute to a very wide spread of the alga in the Mediterranean. We predict that spread will be greatest during summer when a large proportion of fragments can re-attach to the substratum, even at shallow sites. Such information is important for the understanding of the ecology of this species and, with the help of hydrographic studies, in the prediction of its patterns of geographic dispersal
Persistence of biological invasion effects: recovery of macroalgal assemblages after removal of Caulerpa racemosa var.cylindracea
No full textHabitat effect on spatio-temporal variability of size and density of the introduced alga Caulerpa taxifolia
No full textShort-term effects of nutrient enrichment of the sediment and interactions between the seagrass Cymodocea nodosa and the introduced green alga Caulerpa taxifolia in a Mediterranean bay
No full textExploring the success of manual eradication of Caulerpa racemosa var cylindracea (Caulerpales, Chlorophyta): the effect of the habitat
No full textA PILOT STUDY OF NUTRIENT ENRICHED SEDIMENTS IN A CYMODOCEA NODOSA BED INVADED BY CAULERPA TAXIFOLIA
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