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  • Caribbean Damselfish Recolonize Reefs Following Coral Restoration
  • Sarah A. Merolla (bio), Allison J. Holevoet (bio), Samantha L. Musser (bio), and Graham E. Forrester (bio)

Reef-building corals are foundation species that create habitats for themselves and other organisms. For this reason, coral declines over the past 30 years (Gardner et al. 2003) have triggered widespread declines in fishes that occupy coral reefs (Paddack et al. 2009). Coral restoration thus has the potential to both rebuild coral populations and recreate habitat for fishes (Rinkevich 2005), but few studies have tested whether fish populations respond to coral restoration (Caibatan 2008, Yap 2009). In this study, we document the colonization of a degraded reef in the British Virgin Islands by a common reef fish, the 3-spot damsel (Stegastes planifrons), following the restoration of an important reef-building coral, the elkhorn coral (Acropora palmata), to the site.

Many reef fish use live coral as a habitat, with most preferring structurally complex corals such as Acropora (Clarke 1977). Elkhorn coral formerly dominated shallow-water reefs in the Caribbean, but has declined severely over the past 30 years (Vollmer and Kline 2008). Three-spot damsels are territorial herbivorous fish that often associate with branching and foliose corals as adults, probably for shelter, and frequently occupied elkhorn coral before it declined (Precht et al. 2010). In contrast, when juvenile 3-spots first colonize reefs after a planktonic larval phase, they appear to select foliose and columnar corals like lettuce leaf corals (Agaricia spp.) and boulder star corals (Montastraea annularis) (Tolimieri 1995, Gutiérrez 1998, Lirman 1999, Precht et al. 2010).

The restoration site, White Bay, is near Guana Island in the British Virgin Islands (18.473°N, −64.575°W) (Forrester et al. 2011). Elkhorn coral has been absent from the shallow (1–3 m depth) reefs in White Bay for at least 22 years, but based on skeletal remains and anecdotal reports, was formerly common. Other live corals are also rare at the site (1.6% cover in 2005) (Forrester et al. 2011). From 2005–2011, 832 fragments of elkhorn coral were transferred to White Bay from nearby source sites and attached to the reef. All transplanted corals were tagged individually and their locations were mapped at the time of transplant. Their growth and survival was monitored until 2012 (Table 1) (Forrester et al. 2011, 2012, 2013a, 2013b, 2013c).


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Figure 1.

A newly settled 3-spot damsel (shown close-up in the inset) occupying a transplanted elkhorn coral

Tracking the response of 3-spot damsels to the transplanted corals was not originally a goal of the restoration project, but was investigated starting in 2010 when we noticed newly settled 3-spots occupying transplanted corals (Figure 1). In August 2010, divers systematically searched the site by swimming in a zig-zag pattern over the reef’s surface and using the tagged corals as reference points to [End Page 353] ensure the entire reef was inspected. This search revealed 19 juvenile 3-spots (7–20 mm standard length [SL]) on the White Bay reefs, all occupying transplanted elkhorn corals. In August 2011, a similar search revealed 39 juvenile 3-spots. All small juveniles (< 20 mm SL, < 1 month post-settlement, Levin et al. 2000) were associated with a transplanted coral, as were 14 of the 24 large juveniles (20–30 mm SL, 1–2 months post-settlement). In July 2012, we found 93 juvenile 3-spots at the site. Sixteen of the 59 small juveniles occupied transplanted corals, as did 8 of 34 larger juveniles. One of us (G. Forrester) has visited the White Bay site ≈30 times per year since 1992 while working on other fish ecology projects. No juvenile 3-spot damsels were observed from 1992–2009, so we are reasonably confident they were absent, or extremely rare, until 2010 (Table 1). Adult 3-spots, however, were observed every year, and presumably immigrate from deeper reefs nearby.


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Table 1.

History of elkhorn coral restoration at the study site and colonization by juvenile 3-spot damsel. Displayed are the number of elkhorn coral transplanted each year and the total number present at...

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