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An introductory study on composition and abundance of corals using an imaging survey technology in the South China Sea (Sanya, China)



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J. Bio. & Env. Sci.
11 | Xiaojuan et al.
An introductory study on composition and abundance of corals
using an imaging survey technology in the South China Sea
(Sanya, China)
Xiaojuan Xu1, Bo Yuan1, Yuemin Liu1, Weidong Li2, Zhihao Wang3, Lian Ming Wang1,
Pei-Zheng Wang4, Farnaz Mahmoudi Shikhsarmast*1
1College of Marine Science and Technology, Hainan Tropical Ocean University, Sanya, China
2College of Ecology and Environment, Hainan University, Haikou, China
3College of Fisheries and Life Sciences, Hainan Tropical Ocean University, Sanya, China
4College of Ecology and Environment, Hainan Tropical Ocean University, Sanya, China
Article published on July 18, 2021
Key words: Distribution, Diversity, Soft Corals, Stony Corals, South China Sea
Coral reefs are one of the important marine ecosystem in the oceans. This study evidenced the composition and
abundance of coral communities in protected and non-protected areas in Sanya (Hainan, China). Our results
showed that different localities have different communities of soft and/or stony corals. Regarding to our findings,
Yalong Bay that it is under protection program represented high coverage of corals, especially soft corals. It is
documented that protection program can be introduced as one of the major methods to preserve coral reefs.
*Corresponding Author: Farnaz Mahmoudi Shikhsarmast
J. Bio. & Env. Sci.
12 | Xiaojuan et al.
Coral reefs are one of the unique and much important
ecosystem in the oceans (Knowlton, 2001),
supporting crucial aquatic habitats for many marine
organisms (McClanahan et al., 2002; Hughes et al.,
2003). Despite their importance, due to global
warming, the frequency and extent of corals bleaching
around the world have been increased, and the
coverage of coral reefs has been decreased
significantly (Brown, 1997; Chou and Loo, 1994; Chou
2002; Seah et al. 2015; Lu et al. 2021ab). The growing
risk of coral reefs destruction can confirm the
importance of constantly monitoring of composition
and abundance of corals.
Coral reefs are distributed widely in South China Sea
and have importance ecological roles in local
economic development (Seah et al. 2015, Benayahu et
al. 2012; 2018). There is a lack of information on
ecological status and communities’ structure of coral
reefs in Hainan Province (China) especially in the
territory of the Sanya city, due to the lack of
sequential taxonomic studies. It has caused that our
knowledge on coral diversity and communities be
much limited. Although over the last few years,
scientific evidences have documented the potential of
corals in modern medicine (Hildemann et al., 1977;
Reina et al., 2011; Cooper et al., 2014; Elkhawas et
al., 2020), corals have had a special position in
traditional Chinese medicine (Huang et al., 2012; Lin
et al., 2013; Liang et al., 2018). Therefore, this has
caused that corals being threatened by humans for
medical usage. Additionally, the development of
tourism industry and ocean transportation have risen
the hazard of corals damage (Fong et al., 1995; Madin
et al., 2006, 2014). Recently, Administration of
Hainan-Sanya National Coral Reef Nature Reserve
has been administering protection program to
conserve Sanya coral reefs against of human
activities. Human activities are one of the most
important factors that can damage and alter
composition and abundance of coral reefs.
In the present study, we aim to provide a preliminary
landscape of corals distribution and abundance in
Sanya to support effect of local protection program on
preserving coral reefs. The purpose of this
investigation was to determine the composition and
abundances of soft and stony corals to compare the
communities’ structure between protected and non-
protected regions in Sanya.
Materials and methods
Study area
Surveys were conducted in October 2019. Study
locations were in three geographic regions in east part
of Sanya including Sun Bay (SB), Baifu Bay (BB) and
Yalong Bay (YB) which shown in Fig. 1. Information
of localities was summarized in Table 1.
Table 1. Information of studied areas in South China Sea.
Sun Bay
18º 11' 30.94"
109º 36'
40.00" E
Baifu Bay
18º 10' 28.71"
109º 37' 22.02"
18º 12' 44.47"
109º 37' 50.76"
Fig. 1. Geographical position of studied areas
(SB: Sun Bay, BB: Baifu Bay, YB: Yalong Bay).
J. Bio. & Env. Sci.
13 | Xiaojuan et al.
Survey method
At each study locality, a 30m belt was established
along coastal shore. A quadrate (1m2) sequentially
was used along belt and for each quadrate. A Photo
was separately taken to calculate the coverage of soft
and stony corals in each quadrate (Fig. 2). Finally,
coverage of soft corals, stony corals and empty place
were calculate for 30 m2 in each locality. AutoCAD
2020 software was utilized to calculate coverage of
soft corals, stony corals and empty place (Fig. 3).
Fig. 2. Using 30m belt along the coral reefs as
reference line (up), using the quadrate (1m2) along
the belt (down) to calculate coverage of corals.
Our finding showed that highest average and total
coverage belonged to Yalong Bay with 0.44m2/
quadrate and 13.32m2/30m2, respectively. On the
other hand, Sun Bay shoed the lowest average and
total coverage with 0.11 m2/quadrate and
3.50m2/30m2. Yalong Bay exhibited high coverage of
soft corals (0.44m2/quadrate) while it had the lowest
stony corals coverage (0.62m2/quadrate). Although
Baifu Bay and Yalong Bay represented same average
coverage of stony corals in each quadrate
(0.02m2/quadrate), Sun Bay had poor stony corals
(0.1m2/quadrate). The highest stony corals coverage
was belonged to Sun Bay with 3.27m2/30m2.
Fig. 3. The screen of Auto CAD software to show
calculation method of corals coverage.
The results of average coverage in each quadrate
(1m2) and total coverage in 30 m2 are separately
summarized for each localities in Table 2 and Fig. 4.
Table 2. Average and total coverage of soft and stony corals in studied areas.
Ave. in a quadrate (1 m2)
Total coverage in 30 m2
Soft Coral
Stony Coral
Soft Coral
Stony Coral
Sun Bay
Baifu Bay
Yalong Bay
Fig. 4. value of Average and total coverage of soft and stony corals in studied areas.
J. Bio. & Env. Sci.
14 | Xiaojuan et al.
Our results showed that Sun Bay is the habitat of
stony corals while the Baifu Bay is the host of soft
corals. These two location are non-protected area and
total coral coverage significantly lower than Yalong
Bay, which it is a protected area.
Successive Study on abundance and composition of
coral can help to get knowledge about effect of
regional environmental conditions on coral
communities and help to improve taxonomic
information about local coral reefs (Seah, et al.,
2015). Current investigation studied the coral
communities at fringing reefs of three eastern islands,
including Sun Bay, Baifu Bay and Yalong Bay of Sanya
(Hainan, China). Lirman et al. (2007) utilized a
video-mosaic method to survey the coral reefs
abundance and composition and showed this method
can be used to construct two-dimensional.
In this study, we used the imaging survey technology
to get coverage for each 1 m2. Seah, et al. (2015)
reported that soft corals abundance at Kusu Island
reefs were significantly higher than two other islands
including P. Hantu and P. Semakau in Singapore.
Chanmethakul et al. (2010) documented that
different localities could host different communities.
We have gotten the highest coverage and distribution
of corals at Yalong Bay. This place is under protection
program by local government that diving and fishing
are forbidden. Our results can document that
protection program that has been carried out by
government was a successful project to protect coral
reef at Yalong Bay. With regards to our finding there
is no positive relationship between neighbor localities
and diversity and composition of corals.
To nearby Baifu Bay and Sun Bay show different
composition of coral, while Sun Bay is the host of
stony corals, but in Baifu Bay the highest abundance
belong to soft corals. It is suggested in further studies,
ecological parameters of localities with different coral
composition and abundance to find the effect of
ecological condition on coral diversity.
Overall, in this time the most survey project on
coverage of coral reefs have been done using video
recording technology, here our finding clearly
represented the ability of imaging survey technology to
get the exact results for coverage quantity in coral reef.
It is recommended that imaging survey technology
utilize for future studies on survey of coral reefs.
In conclusion, the abundance and distribution soft
and stony corals are not identical in different
localities that it might be attributed to special
ecological and environmental conditions in each
localities. Additionally in close localities also
composition and density of coral are different that
can be referred to regional environmental situations
(generally water pollution) or fishery activities.
Government protection programs can be one of the
most effective governmental plans to protect coral
reefs. Generally implementation of conservation
program by Administration of Hainan-Sanya National
Coral Reef Nature Reserve had a major impact on the
protection of coral reefs in Yalong Bay.
This study was supported by 2020 Provincial
Undergraduate Innovation and Entrepreneurship Program
(S202011100013) of Hainan Tropical Ocean University and
cooperative agreement provided by Hainan Province
Science and Technology Department Key Research and
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