Marine Resources Assessment for the Marianas Operating ... - SPREP

AUGUST 2005 FINAL REPORT
in deepwater habitats (Veron 2000; Paulay personal communication) and are abundant on upper reef
slopes and lagoons (WPRFMC 2001). Lace corals, Stylaster and Distichopora spp., are abundant
under overhangs or on the roof of caves within the reef under low light from 10 to 20 m, occur in deep
reef conditions swept by tidal currents, and in deepwater habitats (Colin and Arneson 1995; Veron
2000; Paulay personal communication). The branching Solanderia spp. is commonly found in
exposed areas on wave swept shallow outer reefs, caves, or overhanging environments at depth
ranges from 0 to more than 100 m (Colin and Arneson 1995). Hydroids mostly occur on rocky
substrates exposed to wave action and surge, on artificial substrates in harbors (pilings, mooring
buoys), in crevices, overhangs, and caves (Hoover 1998; Kirkendale and Calder 2003).
Life History—Hydrozoans typically alternate generations between motile medusoid and sessile
polypoid phases (Fautin and Romano 1997; Fautin 2002; Ball et al. 2004). Sessile colonies bear
polyps specialized for reproduction that asexually produce medusa buds which develop into freeswimming
dioecious medusae. The medusae spawn freely in the water column. A fertilized egg
develops into a planula that settles, metamorphoses into a polyp, and develops a sessile colony
(Fautin and Romano 1997; Ball et al. 2004). In some cases, however, polyp or medusa stages are
entirely lacking for some hydrozoans (e.g., trachymedusans do not have a polyp stage) (Collins
2002). The primary polyp can produce other polyps asexually to form a colony (Fautin and Romano
1997).
♦ Corals (Scleractinian Anthozoans)
Status—Stony corals are managed in Micronesia as part of the PHCRT by the WPRFMC (2001). At
least 377 scleractinian species (377 stony corals) have been reported from CNMI and Guam (Randall
2003) and have EFH designated within the boundaries of the study area (WPRFMC 2001; NMFS
2004c). Major and minor coral (curio trade) fisheries exist within the western central Pacific (Hodgson
1998). Within the study area, coral collecting is banned in CNMI under regulations that prohibit the
collection of hermatypic corals (Green 1997) and on Guam strict laws regulate harvesting dead or live
corals except for educational or research purposes (Hensley and Sherwood 1993).
Distribution—Communities of scleractinian reef-building (hermatypic) and non-reef building
(ahermatypic) corals grow in tropical and subtropical seas globally (Veron 1995; Veron 2000). The
Pacific Ocean contains the most diverse coral fauna in the world (Colin and Arneson 1995; Veron
2000).
Habitat Preferences—Stony corals develop colonial forms that may be branching, tabulate, massive,
or encrusting, or develop solitary, free-living forms (e.g., mushroom corals) (Veron 2000; WPRFMC
2001). Stony corals are found from the sea surface in nearshore environments down to the deep-sea
in more than 6,000 m water depth (Veron 2000; CoRIS 2003; Freiwald et al. 2004; Roberts and
Hirshfield 2004). The hermatypic coral fauna are found in a multitude of habitats including shallow
surf zones and submerged areas of reef flats, lagoon patch-reef zones, patch reefs, and reef slopes
(Veron 2000). Ahermatypic corals colonize areas of low scleractinian coral or algal occurrence
including poorly illuminated or even dark biotopes in caves, trenches, and in deep zones of the reef
(Sorokin 1995; WPRFMC 2001).
Life History—Hermatypic corals reproduce by sexual (external fertilization and development and
brooded planulae, bisexual, unisexual) and asexual (brooded planulae, polyp-balls, polyp bail-out,
fission, fragmentation, and re-cementation) development (Veron 2000; WPRFMC 2001; Fautin 2002).
Corals may be free spawners (12 month maturation cycle) or brooders (several cycles per year)
depending upon their geographic distribution (WPRFMC 2001). In the Marianas, for some corals
spawning occurs 6 to 12 days following the June and July full moons (DoD 1999). Mushroom corals
are asexual (budding, fragmentation or natural regeneration through fracture) or sexual (dioecious or
unisexual) (Veron 2000).
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