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Biological Invasions by Marine Jellyfish 245
Dawson et al. (2005) did note, however, a key exception where one cryptic
species (Aurelia sp. 1) showed global distribution likely related to historical
shipping activity. They concluded, based on this species’ limited ability to traverse
the Pacific Ocean, that its global distribution was invasive and mediated
(possibly multiple times) by shipping (Dawson 2003; Dawson et al. 2005).
Another of their species (Aurelia sp. 4) was also identified as invasive in
Hawaii from an Indo-Pacific origin (Dawson et al. 2005). In sum, these findings
illustrate a realization that many of our highly recognizable ‘cosmopolitan’
species are, in fact, probably historically invasive.
14.3.5 Maeotias marginata, Blackfordia virginica,
and Moerisia lyonsii (Hydrozoa)
Three species of invasive hydromedusae are noteworthy: Maeotias marginata,
Blackfordia virginica, and Moerisia lyonsii. All three are believed native to the
Black Sea/Sea of Azov region: M. marginata: Borcea (1928) and Ostroumoff
(1896), both as discussed in Mills and Sommer (1995); B. virginica: Thiel
(1935), as discussed in Mills and Sommer (1995); M. lyonsii: Kramp (1959), as
discussed in Calder and Burrell (1967). However, all three have successfully
invaded regions of the Atlantic, Pacific, and Indian (except M. marginata)
oceans (Calder and Burrell 1967; Mills and Sommer 1995; Mills and Rees
2000; Väinölä and Oulasvirta 2001). Interestingly, all have been found in the
Chesapeake Bay (Mayer 1910; Calder and Burrell 1967, 1969) and San Francisco
Bay (Mills and Sommer 1995; Mills and Rees 2000).While no major negative
impacts have been described for any of these three invasive hydromedusae,
M. lyonsii was noted by several authors for its ability to foul
experimental or culturing mesocosms (Sandifer et al. 1974; Petersen et al.
1998; Purcell et al. 1999).
14.4 Jellyfish Invasions: Blooms and Ecosystem Controls
Gelatinous zooplankton blooms exert tremendous pressure on marine planktonic
food webs, including in regions of important commercial fisheries (Purcell
1985, 1989; Purcell and Arai 2001; Purcell et al. 2001). In its native range M.
leidyi seasonally forms large blooms, especially in enclosed bays and estuaries,
exerting significant predation pressure on zooplankton species (Feigenbaum
and Kelly 1984; Purcell and Decker 2005), as well as on the eggs and larvae
of economically important fish and shellfish (Purcell et al. 1991, 1994).
This is especially true for the Chesapeake Bay (USA), where M. leidyi, along