Tonga - Vava'u (TOVA35)

Setting

Aquarium. Lagoonal patch reef. On the north side the reef slopes moderately from 5 m to 15-18 m, then gradually to 20-23 m before ending in sand.

General benthic features

The reef has a shallow terrace, mostly flat, 2-4 m deep that consists of scoured hardground in places, soft corals, and a mixed branching coral community. Off the southeast end in 6-12 m is an extensive Porites reef with massive Porites colonies, 2-5 m diameter and up to 3 m tall. These are surrounded by large staghorn coral thickets. The rest of the patch has a moderately steeply sloping community. There were numerous table acroporids and staghorn clumps running down the reef from 5-10 m depth. At mid depths there was a mix of massive corals, encrusting Favites, high numbers of crustose Isopora, table acroporids, Merulina, Goniastrea, and other species with 40-60 cm relief, small patches of rubble, and large 1-2 m dead patches with damselfish algal lawns (20-60% turf). At 20 m were 1-2 m clumps of Pachyseris rugosa, 20-60 cm table acroporids, columnar Isopora, medium Favia stelligera, high numbers of Stylophora, small Lobophora, Mycedium, Leptoseris, and Pachyseris plates with 20-40% cover, 30% turf, 20% CCA, 20% Peyssonnelia, and a lot of rubble in small sand patches between the corals. The sand flat at the base of the reef had some larger table acroporids at a low density (1 per 3-5 m²).

Coral cover

• Reference: Khaled bin Sultan Living Oceans Foundation, Global Reef Expedition (in situ transect)
• Coral cover 41% (the expedition's in situ transects).
• Transect mean 41 ± 3.1% SE (n = 5 transects; Living Oceans Foundation per-transect benthic data); the headline above is this all-transect mean.

Stressors

Anderson's sampling sheet records colony 64 as about 90% bleached and colony 63 as 20% bleached; on the 25 September return, one of the seven colonies sampled was 20-30% bleached and one 10% bleached. At mid depths the survey notes record large 1-2 m dead patches taken over by damselfish algal lawns. The Living Oceans Foundation transects here recorded 0.6% cyanobacteria and no recently dead coral.

Comparisons with other data

Coral Health Index 1.50/5 (Mayfield et al. 2021, Platax).

Dive record

TOVA35 (Vava'u): surveyed 22 and 25 Sep 2013 during the Khaled bin Sultan Living Oceans Foundation Global Reef Expedition.

Other notes

Anderson was busy sampling corals at this site, so the site description is derived from the Living Oceans Foundation survey team's site notes and benthic transect data. Those transects recorded 41% hard coral cover. Anderson sampled 4 Pocillopora colonies here (3 labeled Pocillopora acuta; 1 labeled Pocillopora damicornis), numbered 63, 64, 65, 66 in the expedition series; the sampling sheet records colony 64 as mostly (about 90%) bleached and possibly unhealthy and colony 63 as 20% bleached. Anderson returned on 25 Sep 2013 and sampled seven more colonies, numbered 77 to 83, one of them 20-30% bleached and one 10% bleached. The photographs shown for this site are close-ups of the colonies Anderson sampled, so nothing here describes the reef's habitat, structure, or condition from imagery.