Searching for the competitive ability of the alien seagrass Halophila stipulacea with the autochthonous species Cymodocea nodosa
The tropical seagrass Halophila stipulacea (Forsskål) Ascherson, 1867 entered in the Mediterranean Sea through the Suez Canal more than 100 years ago. In coastal-marine ecosystems the spatial niche of H. stipulacea is often overlapped with that of native Mediterranean Sea seagrasses and therefore it...
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Published in | NeoBiota Vol. 83; pp. 155 - 177 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
Sofia
Pensoft Publishers
11.05.2023
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Subjects | |
Online Access | Get full text |
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Summary: | The tropical seagrass
Halophila stipulacea
(Forsskål) Ascherson, 1867 entered in the Mediterranean Sea through the Suez Canal more than 100 years ago. In coastal-marine ecosystems the spatial niche of
H. stipulacea
is often overlapped with that of native Mediterranean Sea seagrasses and therefore it might out-compete them. Aiming to better understand its invasiveness potential, we monitored a Southern Mediterranean shallow coastal-marine water habitat from August 2010 to August 2011, where
H. stipulacea
co-occurred with the native seagrass
Cymodocea nodosa
(Ucria) Ascherson, 1870. Besides, the year-round dynamics of
H. stipulacea
was also monitored in four periods. To test the hypothesis that the presence/absence of
H. stipulacea
may have an effect on
C. nodosa
density, we analyzed the shoot density of
C. nodosa
in 8 sites, 4 sites where
H. stipulacea
was present (impacted sites) and 4 where
H. stipulacea
was absent (control sites). The results showed significant differences in
C. nodosa
shoot density according to the presence/absence of
H. stipulacea
, with the lowest values observed in sites where it co-occurred with
H. stipulacea
. We hypothesize that the dense rhizome-sediment net created by
H. stipulacea
can interfere with
C. nodosa
density, pushing down its rhizomes in the anoxic layer. The leaf features of
H. stipulacea
were generally comparable to those of other Mediterranean populations. In January 2011 a significant decline of
H. stipulacea
was observed, maybe related to changes in the environmental conditions that have become unfavorable (e.g. hydrodynamics, turbidity) and, unexpectedly, the seagrass disappeared in April 2011. In January, we also observed the occurrence of the green alien alga
Caulerpa cylindracea
Sonder, 1945 which rapidly invaded the bare substrate left by
H. stipulacea
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ISSN: | 1619-0033 1314-2488 |
DOI: | 10.3897/neobiota.83.99508 |