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Galil 2007). In southeastern Australia, total numbers of fishes were similar when
Caulerpa and native seagrass beds were observed (York et al. 2006). However, spe-
cies richness was significantly reduced in Caulerpa patches with high proportions
of gobiid fishes and limited numbers of syngnathid and monacanthid fish species
(York et al. 2006). In NSW, Gollan and Wright (2006) found that there were only
four herbivores that co-occurred with C. taxifolia . The fish Girella tricuspidata , the
sea hare Aplysia dactylomela, and two mesograzers, the amphipod Cymadusa
setosa and the polychaete Platynereis dumerilii antipoda, all preferentially fed on
other food sources in lab and field trials. Pinnegar and Polunin (2000) examined
C. taxifolia impacts on the labrid fish Coris julis , which has limited migration and
dispersal. Oxidative stress was examined for foraging C. julis in three habitat types:
meadows of C. taxifolia , C. prolifera , and P. oceanica in waters surrounding
Mallorca Island, Spain. Increased activity of liver antioxidant enzymes in Caulerpa
meadows suggested ongoing detoxification of caulerpenyne by C. julis if algal
blades or organisms that previously have consumed Caulerpa blades were ingested
(Pinnegar and Polunin 2000). Even humans have suffered ill effects from cauler-
penyne. Patients have been diagnosed with food poisoning after consuming Sarpa
salpa , a fish that consumes C. taxifolia in the Mediterranean; doctors also docu-
mented neurological disorders such as amnesia, vertigo, and hallucinations associ-
ated with caulerpenyne consumption (DeHaro et al. 1993).
Predators have been documented to be negatively impacted by C. taxifolia in
ways not related directly to caulerpeyne. For example, Caulerpa's dense clumps of
rhizomes and stolons can form obstructions to fish trying to feed on benthic inver-
tebrates (Fig. 15.2). Levi and Francour (2004) documented obstructions with the
striped red mullet Mullus surmuletus . Longpierre et al. (2005) additionally found
that the mullet's foraging effort increased with increased density of C. taxifolia with
significantly fewer large individuals in Caulerpa meadows (1.2%) vs. 27.8% in
Posidonia seagrass beds. The number of individuals of the bivalve Anadara trape-
zia increased in areas of C. taxifolia relative to unvegetated controls in Australian
waters (Gribben and Wright 2006), possibly the result of increased structural com-
plexity. However, delayed reproductive development, changes in timing of spawn-
ing, and fewer oocytes and sperm were all associated with Caulerpa beds relative
to controls (Gribben and Wright 2006).
15.3.7
Other Characteristics that Promote Invasiveness
Other aspects of the life history of the genus Caulerpa that promote “invasiness”
include (1) ability to survive burial in sediment, and (2) ability to extract nutrients
from multiple sources. Typically, unicellular species such as Caulerpa can translo-
cate chloroplasts away from portions of the thallus if buried or held in darkness.
Glasby et al. (2005b) documented that partial burial of Caulerpa in sediment had
very limited impacts on individuals, while total burial for 17 days resulted in only
35% survival. While many seagrasses obtain a large fraction of nutrients from the
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