Corresponding author: Zarinah Waheed (
Academic editor: L. van Ofwegen
Layang-Layang is a small island part of an oceanic atoll in the Spratly Islands off Sabah, Malaysia. As the reef coral fauna in this part of the South China Sea is poorly known, a survey was carried out in 2013 to study the species composition of the scleractinian coral families
Waheed Z, Benzoni F, van der Meij SET, Terraneo TI, Hoeksema BW (2015) Scleractinian corals (Fungiidae, Agariciidae and Euphylliidae) of Pulau Layang-Layang, Spratly Islands, with a note on
Pulau [island] Layang-Layang is a small island standing 2 m high on the southeast rim of a reef known as Swallow Reef (
Being remote, the reef was regarded to be in pristine condition (
A massive coral bleaching event during the 1997–98 El Niño event had also affected the reefs of Layang-Layang. Up to 40% of the coral colonies at less than 10 m depth and 25% at 10-20 m depth were bleached at 55 monitoring sites, but by 1999 the corals had recovered or were overgrown with zoantharians and soft corals (
A recent calamity to confront the reefs was an outbreak of the crown-of-thorns (COT) seastar,
While several short research expeditions and surveys have been carried out to collect baseline information on the marine biodiversity of Pulau Layang-Layang (
Pulau Layang-Layang (
Water parameters were measured at 10 m depth of each survey site (Suppl. material
Layang-Layang in the South China Sea is influenced by the monsoon system (see
Fieldwork was carried out 24–30 March 2013 on the reefs of Layang-Layang. Due to safety issues, surveys were confined to dive sites designated for tourism around the atoll. A total of 18 sites was surveyed on the outer slope of the reef wall from a maximum depth of 40 m to the shallow reef crest of 1 m using the roving diver technique (
Research area at Pulau Layang-Layang, Spratly Islands. Survey sites are numbered 1-18, and HR for the House Reef. Depth contours are indicated in metres (smaller font). For a complete georeferenced list of localities and depths of survey sites, see Table
Locality data of survey sites at Pulau Layang-Layang, Spratly Islands.
Site | Site name | Latitude (N) | Longitude (E) | Date | Max. depth (m) |
---|---|---|---|---|---|
1 | Snapper Ledge |
|
|
24/03/2013 | 31.8 |
2 | Dogtooth Lair |
|
|
24/03/2013 | 30.7 |
3 | Wrasse Strip |
|
|
25/03/2013 | 30.3 |
4 | Shark Cave 1 |
|
|
25/03/2013 | 32.6 |
5 | D’Wall |
|
|
25/03/2013 | 33.8 |
6 | Gorgonian Forest |
|
|
26/03/2013 | 37.9 |
7 | Shark Cave 2 |
|
|
26/03/2013 | 27.9 |
8 | Crack Reef |
|
|
26/03/2013 | 29.3 |
9 | Coral Café |
|
|
27/03/2013 | 38.5 |
10 | Wrasse Strip 2 |
|
|
27/03/2013 | 33.5 |
11 | Wreck Point |
|
|
27/03/2013 | 33.3 |
12 | Wreck Point 2 |
|
|
28/03/2013 | 40.4 |
13 | Navigator Lane |
|
|
28/03/2013 | 36.8 |
14 | The Point |
|
|
28/03/2013 | 34.2 |
15 | Coral Café 2 |
|
|
29/03/2013 | 36.7 |
16 | Mid Reef |
|
|
29/03/2013 | 37.7 |
17 | The Valley |
|
|
29/03/2013 | 34.8 |
18 | Runway |
|
|
30/03/2013 | 40.3 |
Coral specimens were identified by referring to taxonomic literature (
Specimens of a thin morph of
Seven samples of
Coral samples were sequenced for two markers, namely the mitochondrial intergenic spacer between CO1 and 16S-rRna (IGR for short;
Primer pairs, gene region, fragment size, annealing temperature and references of the molecular markers used in this study.
Name | Primer | Gene region | Fragment size | Annealing temp. | Reference |
---|---|---|---|---|---|
AGAH | GCT TGA CAG GGT TTC CAA GA | COI-1-rRNA intron | ~1200 | 54 °C |
|
AGAL | CGC ATT GAA ACA CGA GCT TA | COI-1-rRNA intron | ~1200 | 54 °C |
|
ITS4 | CCT CCG CTT ATT GAT ATG C | ITS1-5.8S-ITS2 | ~700 | 55 °C |
|
A18S | GAT CGA ACG GTT TAG TGA GG | ITS1-5.8S-ITS2 | ~700 | 55 °C |
|
Sequences were aligned on the GUIDANCE server using PRANK algorithm (
Maximum Likelihood (ML) analyses were carried out in Garli 2.0 (
A subset of the
The number of scleractinian corals recorded in the study area is 56 species with 31
Undetermined
Checklist of hard coral families
Family | No. | Species | No. of sites | Figure no. | Previous records |
---|---|---|---|---|---|
|
1 | 1 | 2a | b | |
2 | 15 | - | b | ||
3 | 12 | - | a | ||
4 | 6 | 2b | - | ||
5 | 12 | 2c | - | ||
6 | 1 | - | - | ||
7 | 2 | 2d | - | ||
8 | 6 | 2e | - | ||
9 | 1 | - | - | ||
10 | 11 | 2f | - | ||
11 | 13 | 2g | a | ||
12 | 13 | 2h | a | ||
13 | 15 | 3a | a, b | ||
14 | 5 | 3b | a | ||
15 | 15 | 3c | a, b | ||
16 | 13 | - | - | ||
17 | 7 | 3d | - | ||
18 | 17 | 3e | b | ||
19 | 12 | 3f | - | ||
20 | 4 | 3g | a | ||
21 | 15 | 3h | b | ||
22 | 12 | 4a | - | ||
23 | 5 | 4b | - | ||
24 | 6 | 4c | a | ||
25 | 16 | - | - | ||
26 | 1 | - | - | ||
27 | 1 | 4d | - | ||
28 | 1 | 4e | a, b | ||
29 | 2 | 4f | - | ||
30 | 12 | 4g | - | ||
31 | 9 | 4h | a, b | ||
|
32 | 3 | 5a | - | |
33 | 7 | 5b | a | ||
34 | 5 | 5c | - | ||
35 | 17 | 5d | - | ||
36 | 12 | 5e | - | ||
37 | 9 | 5f | - | ||
38 | 13 | 5g | - | ||
39 | 18 | 5h | a | ||
40 | 12 | 6a | - | ||
41 | 6 | 6b | - | ||
42 | 1 | 6c | - | ||
43 | 1 | 6d | - | ||
44 | 8 | 6e | a | ||
45 | 6 | 6f | a | ||
46 | 3 | 6g | - | ||
47 | 3 | 6h | a | ||
48 | 5 | 7a | - | ||
49 | 6 | 7b | a | ||
50 | 4 | 7c | - | ||
51 | 6 | 7d | a | ||
52 | 14 | 7e | a | ||
53 | 9 | 7f | - | ||
|
54 | 1 | 8a | a | |
55 | 1 | 8b | - | ||
56 | 1 | 8c | a |
Other coral species recorded at Layang-Layang during earlier studies, but not encountered during the present survey are the fungiids
Hard coral species that were not encountered in the present study. Species marked with an asterisk (*) is now considered
Family | No. | Species | Previous records | Status |
---|---|---|---|---|
|
1 | a, b | Verified | |
2 | b | Unverified | ||
|
3 | b | Unverified | |
4 | b | Unverified | ||
|
5 | a, b | Verified | |
6 | a, b | Verified |
Sequences were obtained from 11 and 17
Maximum likelihood phylogram of
Macro- and micromorphology features of the
Specimens of
Specimen RED05
Septocostae of both
Variation of radial elements in
Summary of variation in morphological characters between
Morphological characters |
|
|
---|---|---|
Growth form | Encrusting; paper-thin coralla, club-shaped (specimen from the Maldives) | Encrusting, submassive; may have plate margins |
Corallite (arrangement) | Small and compact (top of the colony), widely spaced (base of the colony) | Irregular spacing and arrangement, in parallel rows towards the margin |
Corallite (shape) | Circular, plocoid, flattened edges when inclined towards the margin | Irregular shape, but may be somewhat circular |
Theca | Distinct; plocoid | Mostly lacking, synapticulothecate if present |
Columella | Well-developed; peg-like, single, rounded or twisted rod | Several fused processes |
Septo-costae | Compact, dense granulated sides | Compact, septa alternate between thin with fine granules and thick with spines |
Radial elements | Beaded granules | Tapers into straight ridge, may have smooth margins |
Lateral faces | Granules in rows or scattered on the surface, may form short series of menianae | With granules and meaninae |
The total number of coral species noted at Layang-Layang is lower than that of other localities in Sabah where similar surveys have been conducted. Nevertheless, the overall species diversity is considered high even for fungiid corals, despite the fact that steep reef walls are hostile environments for free-living mushroom corals, as they can get dislodged from these drop-offs (
Among the new coral records for Layang-Layang are five rarely documented species, i.e.,
Corals of three
Three coral species that have been reported from Layang-Layang but were not observed in the present study are the fungiid
Many coral colonies in Layang-Layang appeared small in size, and most were juveniles. This was consistent across the reef sites for most coral families including those targeted in our study. For example, the largest collected
There is no information on the extent of damage caused to the reefs and the rate of recovery from the COT outbreak in 2010, as the reefs of Layang-Layang are not monitored regularly. Many studies have reported the effects of COTs to reefs in terms of coral cover loss and changes in coral assemblage (e.g.
The IGR marker has proven to be successful in resolving species boundaries in the family
For all specimens in the
Upon re-examining the morphological characters of the
Although
Based on the findings of this study, the “true”
The name
The coral species list for the families
An integrative molecular and morphological approach was utilised to determine that specimens identified as
Research permits for Layang-Layang were granted by the Economic Planning Unit and the National Security Council of the Prime Minister’s Department, Malaysia, and the Sabah Biodiversity Council. Travel expenses for Z. Waheed was funded by the A.M. Buitendijkfonds, The Netherlands. We acknowledge the Marine Research Station Layang-Layang (MARSAL) for the visit to the field station at Layang-Layang. We thank the team at Avillon Layang-Layang Resort for living and diving logistics, the managing director Eugene Foo and divemasters Jasper Bell, Rozlan Wahab and Amanda La Brooy for fruitful discussions. Loyalty Island data was collected during the BIBELOT campaign in 2014 onboard RV Alis of IRD at Nouméa. Sampling permits were granted by the Loyalty Islands Province, New Caledonia. BW Hoeksema is grateful to Cecile Fauvelot and Claude Payri for the invitation to join this expedition, and to Francesca Benzoni and Paola Galli for allowing him to participate in the Maldives International Reef Biodiversity Workshop in 2014, which enabled him to obtain data on
Table S1
measurement
Physical properties of seawater at Pulau Layang-Layang.
Table S2
specimens data
Coral samples included in the molecular analyses with supporting collection and locality data.
Table S3
specimens data
Species occurrence of hard coral families
Figure S1
molecular data
Maximum likelihood phylogram of
Figure S2
specimens data
Variation of corallite form and structure in