As a genus of Cholorophyta in the family CodiaceaeUdoteaceae,Halimeda is an important alga in the
tropical shallow seas around the world. As a representative plant molecule of the biodiversity of coral
ecosystem, Halimeda is also an important producer of calcium carbonate and a kind of important reefbuilding
plants. Based on a review of the recent ten years of investigation and research on Halimeda,
this paper reports the ecological characteristics of Halimeda in the coastal reef of Shidao, Xisha Islands.
We found in the shallow reef that the Living Halimeda recovered naturally after the stop of harbor
construction and dust emission for 3 years, indicating that Halimeda was a sensitive indicator of the
relationship between harbour construction and natural restoration of the environment.
Among the producers of Marine calcium carbonate, Halimeda is highly respected. It is not
only one of the main contributors of tropical and subtropical Marine calcium carbonate [1,2],
but also forms Halimeda Proglottid rock through fossil proglottid. It is also an important reefbuilding
plant in modern shallow seas of xisha Xisha islands [3,4]. In the world’s oceans, such
as Grand Bahama Beach, the Great Barrier Reef, the Caribbean reef area, the South China Sea,
and other waters, Halimeda is widely found, widely distributed in modern reef sediments, the
proportion can be up to 70%. As early as 1816, Lamouroux had noticed that Halimeda were
common algae in the tropical shallow sea environment. They grew in a branching, segmented
way, and many proglottids fell off and became carbonate sediments in the tropical shallow
Ginsburg (1956) found in Florida that the sedimentary enrichment area of Halimeda was
roughly similar to that of Coralline algae, distributed in the reef flat, Grey sand Island and
lagoon bottom, and reached the maximum in the lagoon bottom behind the reef, forming a
large area of growth. The Halimeda Bioherm was formed, which was mainly composed of
Halimeda. Eventually, many of these mounds joined together to form the Halimeda Bank. In
1985, the sixth International Conference on Coral Reefs focused on the discussion of Halimeda,
which attracted extensive attention from the Marine scientific community and led to a series
of studies on it.
Vroom et al.  found that Cymbidium paniculata continued to grow at a rate of one node
per branch per day and formed segments. The time to full maturity is 30 days or faster [5-9].
Nowadays, it has been recognized that the phytolith sediments are the main components of
the tropical Marine sediments [1,10-12]. They may even contribute more to the carbonate
sediment budget in tropical oceans than corals in coral reef ecosystems [2,13,14], and form
basement deposits and improve the environment [6,15-18], becoming important builders of
islands and carbonate platforms [19-28].
Through the research on the process and mechanism of the calcification of Halimeda, the
impacts of environmental changes, such as ocean acidification, on the calcification of Marine marine organisms, can be evaluated, including the physiological
characteristics of Halimeda and the changes in the total calcium
carbonate content [29-35].
In the process of ocean acidification caused by modern
island and reef seaports construction and fishery production, the
physiological response of Halimeda adapted to such acidification
may change [36-40].
For the last ten years, our survey area has remained in the
horseshoe-shaped Xuande Atoll, focusing on the shallow lagoon
and its cay towards the northeast of Shidao island. The earliest
sampling survey was conducted in 2012, and many samples were
obtained within a short period of time. It is exciting and interesting
to test and study them and compare their differences with fossil
Halimeda reef [3,4].
This work continues to this day. During this period, construction
of a public pier began one year later about 2 kilometers from the
survey area; Persistent an investigation was carried out to observe
and compare the distribution and the occurrence of Halimeda.
Three years later, it was found that there was a decrease of the
Halimeda in the survey area, and the collection of Udotea was
carried out. A relatively new sampling survey was conducted in July
2019, and two species of Halimeda were found (Figure 1).
Figure 1: Two species of Halimeda were collected
on July 21, 2019.7.
The latest survey was conducted in July 2020, validating
the findings of the previous year’s survey for the purpose. The
underwater area shooting was increased to determine the large
area covered by Udotea. It was found that the area of the broken
wave zone in the investigated sea area was normal, but the chalky
deposition was distributed outside the broken wave zone.
1. The scientific exploration well confirmed that the fossils Fossil
Halimeda proglottid rock of were found in the research area
of neogene Neogene in the period of 400 meters of geological
history , indicating that Halimeda was the owner here in the
period of geological history.
2. Before the construction of the port, Halimeda was lush; A large
number indicates a good Marine environment.
3. Dust in the survey area should be the most an important factor
for the influence of three years after the construction of the
4. Technology and method are important, and technological
progress and continuous inspection and verification are
5. The natural recovery capacity of the ocean is beyond
imagination, and the area currently covered by chalky
sediments is less than a few hundred square meters, located
outside the rupture zone. Therefore, the rupture cleans the
dirt and maintains the Marine environment.
6. In 3-5 years, the impact of harbor construction will be
eliminated by the nature of the sea. Therefore, respecting and
reverence nature is the highest concept of construction.
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Professor, Chief Doctor, Director of Department of Pediatric Surgery, Associate Director of Department of Surgery, Doctoral Supervisor Tongji hospital, Tongji medical college, Huazhong University of Science and Technology