Mesophotic Coral Ecosystems

Table 1. Deepest in situ observations of obligate zooxanthellate corals by island (see Figure 1 for location).

Deepest in situ observations of obligate zooxanthellate corals by island.

Latitude ( o N)

Depth (m)

Reference

Location

Hawai ‘ i

19.5

153

Kahng and Maragos 2006

Maui Nui

21.0

131

Kahng and Maragos 2006

O ‘ ahu

21.3

115

Blythe-Skyrme et al. 2013

Ni ‘ ihau-Kaula

21.6

111

pers. obs., HURL P5-571

Kaua ‘ i

21.9

110

pers. obs., HURL P4-223

French Frigate Shoals

23.7

77

Blythe-Skyrme et al. 2013

Pearl & Hermes

27.9

67

Luck et al. 2013

Midway

28.2

66

Luck et al. 2013

Kure

28.4

66

Luck et al. 2013

While MCEs in Hawai‘i are subject to the same natural and anthropogenic disturbances as other MCEs (reviewed in Bongaerts et al. 2010a), Hawai‘i’s evolutionary isolation and low species diversity of shallow-water marine fauna likely increase its susceptibility to non-indigenous invasive species from underrepresented taxa (Stachowicz and Tilman 2005, Kahng 2006). At mesophotic depths in Maui Nui, the invasive octocoral Carijoa riisei , which is cryptic in shallow-water, has been reported to be dominating rugose substrate and overgrowing antipatharian and scleractinian fauna (Kahng and Grigg 2005, Kahng 2007). On the island of Oahu, the invasive green alga Avrainvillea sp. (first reported in 1981) has been

observed forming vast meadows to depths of 90 m (Peyton 2009, Spalding 2012). At French Frigate Shoals, the bluestripe snapper, Lutjanus kasmira , was recorded as the second most abundant fish at 30–90m(Kane et al. 2014). Introduced toOahu in 1955, it is prolific in shallow water across the archipelago (Friedlander et al. 2002, Gaither et al. 2013). Therefore, its abundance on mesophotic reefs in the Main Hawaiian Islands is probably significant. These reports demonstrate the potential susceptibility of Hawai‘i’s MCEs to biological invasions, which have been well documented in shallow-water and terrestrial ecosystems (U.S. Congress OTA 1993, Coles and Eldredge 2002, Eldredge and Carlton 2002, Smith et al. 2002).

MESOPHOTIC CORAL ECOSYSTEMS – A LIFEBOAT FOR CORAL REEFS? 42