Malaysia is a maritime nation blessed with rich marine biodiversity and extensive coral reefs that create an amazing underwater forest (Misni & Jarami, 2021 ; Misman et al., 2023 ). Coral reefs and their associated habitats are biologically and economically important in Malaysia. They provide food for local people, a shelter for marine animals, coastal protection, and recreational and tourism activities (Praveena et al., 2012 ). Although the corals are widespread in Malaysia, its coral reefs are among the most threatened in the world (Arai, 2015 ; Safuan et al., 2021 ). With the decreasing health of coral reefs globally and mounting ecological pressures, constant monitoring of the reef status is vital for good management and conservation practices. While most of the reefs in Peninsular Malaysia were considered poor or fair, some were in good condition, especially in marine protected areas (MPAs), highlighting the importance of MPAs, such as marine parks, in their conservation (Waheed, 2016 ; Ismail & Goeden, 2022 ).

Many studies have been conducted on coral reef communities in Malaysia, especially in MPAs, to determine the health status of the reefs (Toda et al., 2007 ; Safuan et al., 2021 ; Ismail & Goeden, 2022 ; Yu et al., 2023 ). This interest can be attributed mainly to the growing concern for the conservation and preservation of coral reef ecosystems (Misman et al., 2023 ). However, there has been a steady decline in coral reef health over the last two decades (Praveena et al., 2012 ; Kimura et al., 2014 ; Rudra, 2018 ; Ismail & Goeden, 2022 ). All reefs in Malaysia are considered to be under heavy anthropogenic threat (Praveena et al., 2012 ; Kimura et al., 2014 ). The impact of tourism has been documented as one of the main reasons for the environmental degradation in MPAs (Ismail & Goeden, 2022 ). Fortunately, most reefs can recover with the help of good management, and such management involves regular monitoring of reefs to assess their health status (Rudra, 2018 ).

Coral health status provides information about the health and resilience of the coral reef ecosystems and aids in recognising and addressing the threats facing them (Misman et al., 2023 ). Assessments of the health status of coral reefs have been conducted using a variety of environmental parameters. More commonly, coral reef condition has been determined using a single parameter, such as the live coral cover (Giyanto et al., 2017 ). The assumption is that the higher the live coral cover, the healthier the reef will be.

During 2020, the Covid-19 pandemic led to strict lockdowns in many countries around the globe (Edward et al., 2021 ; Somchuea et al., 2022 ). In Malaysia itself, in response to the pandemic, the government implemented the Movement Control Orders (MCO), which started from 18^th March 2020, and lasted for almost 20 months. During this period, human activities were limited and restricted (Chuan et al., 2021 ). The MCO was anticipated to have a positive impact on the aquatic ecosystem, including coral reefs (Chuan et al., 2021 ; Somchuea et al., 2022 ).

Prior to the Covid-19 pandemic, several studies were conducted at the Pulau Payar Marine Park on its coral reefs, but comprehensive information on coral health and reef communities remained insufficient (Sze et al., 2000 ; Jonsson, 2002 ; Ramli et al., 2016 ; Khodzori et al., 2019 ; Normah et al., 2021 ). Similarly, there was no information collected immediately following the pandemic that could clarify the reduced anthropogenic impacts on the reefs of the marine park. In order to successfully manage the future of coral reefs, an assessment of various aspects of the reef community structure is needed, and regularly updating the information on coral health status is the key to better managing marine park reef ecosystems. Thus, the objectives of this study were to assess the coral health and provide an up-to-date baseline reference on the coral and fish communities of Pulau Payar Marine Park.

2. Materials and Methods

2.1 Study area

The Pulau (= island) Payar Marine Park (PPMP) is located on the west coast of Peninsular Malaysia, between Pulau Langkawi and the mainland of Kuala Kedah. It stretches 2 nautical miles, making up a cluster of four small islets namely, Pulau Payar (the largest), Pulau Kaca, Pulau Lembu and Pulau Segantang (the outermost island to the west of Pulau Payar). All the islands are uninhabited, except by on-duty management authorities from the Department of Fisheries, Malaysia. As a marine park, fishing and other resource extraction activities, either for hobby or commercial purposes, are strictly prohibited (Alias & Mohd. Saupi, 2000 ; Misni & Jarami, 2021 ). However, because of its proximity to the well-known tourism island of Langkawi, located approximately 50 km to the northwest of PPMP, this marine park became a very popular destination, and before the implementation of the MCO, the park was open to the public all year round.

This study was carried out from June 2020 to February 2021 during the implementation of the Malaysian MCO. During that period, PPMP was totally closed to the public. No activity was undertaken except for operational and research purposes employed by the management authorities. For this study, underwater surveys using the Self-Contained Underwater Breathing Apparatus (SCUBA) were carried out at 11 selected sites (Table 1 and Figure 1). All study sites were generally considered tourist spots for SCUBA diving activities.

Table 1. Location and depth profile of the survey sites.

Sampling site	Average depth (m)	Location	Coordinate (Lat. / Long.)
P1	5.5	Pulau Payar	6°3'45.68"N / 100°2'30.51"E
P2	7.0	Pulau Payar	6°3'21.96"N / 100°2'11.04"E
P3	6.0	Pulau Payar	6°3'53.02"N / 100°2'21.16"E
P4	7.0	Pulau Payar	6°4'7.76"N / 100°2'41.59"E
K1	5.5	Pulau Kaca	6°4'18.03"N / 100°3'4.42"E
K2	9.5	Pulau Kaca	6°4'21.53"N / 100°3'2.17"E
L1	6.5	Pulau Lembu	6°4'26.61"N / 100°3'26.88"E
L2	7.5	Pulau Lembu	6°4'22.19"N / 100°3'18.56"E
S1	9.5	Pulau Segantang	6°2'37.30"N / 99°55'29.90"E
S2	8.5	Pulau Segantang	6°2'37.46"N / 99°55'34.15"E
S3	7.5	Pulau Segantang	6°2'40.59"N / 99°55'34.20"E

Figure 1. Map showing the sampling sites of Pulau Payar Marine Park: P1 (House Reef), P2 (Coral Garden), P3 (Lobster Garden), P4 (Porites Garden), K1 (Sunken Boat), K2 (Shark Point), L1 (Eastern Reef), L2 (Rock Point), S1 (Cupak Wall), S2 (Anemone Garden), S3 (Segantang Tip).

2.2 Sampling procedures

Benthic substrate coverage was ascertained using a point interface transect method (Eleftheriou, 2013 ; Ilias, 2022 ). Data were collected at every 1 m interval on duplicated 50 m transects at depths of 5 to 10 m. For every 1 m, all benthos found within 0.25 m from that point were counted and their sizes recorded, following the method by Ismail & Khoo (2019 ). The benthic communities were categorized as biotics (scleractinian coral, non-scleractinian corals, coralline algae and fleshy algae) or abiotics (dead corals, rocks and sands). Dead corals consisted of white, clean coral skeletons without living tissues Ilias, (2022 ). Coral species were also photographed individually for identification and verified up to species level using keys by Kelley (2016 ), Ismail (2021 ) and Veron et al., (2023 ).

Assessments of fish communities were conducted by visual census along the same 50-metre-long transects, following the method described by Eleftheriou (2013 ). The total lengths of fish were estimated in cm, which were later used to calculate biomass. Fish were photographed and identified up to species level using published references (Allen, 2020 ; Froese & Pauly, 2023 ).

2.3 Data analysis

The coral health was determined using a live coral coverage (LCC) value and a two-dimensional coral health index (2D-CHI), which was based on two parameters, namely benthos coverage and fish biomass (Ilias, 2022 ; Kaufman et al., 2011 ; Diaz-Perez et al., 2016 ). The value of LCC is considered poor, fair, good or excellent based on ranges of 0-25%, 26-50%, 51-75% and 76-100% respectively (Ilias, 2022 ). While the 2D-CHI value is categorized as very degraded, degraded, fair, healthy or very healthy based on the values of 0-0.19, 0.20-0.39, 0.40-0.59, 0.60-0.79 and 0.80-1.0 respectively (Kaufman et al., 2011 ; Diaz-Perez et al., 2016 ).

The relative abundance (RA) values for each species were determined following the method by Rilov & Benayahu (2000 ) and were categorized as Not Recorded (RA=0%), Rare (0<RA<0.1%), Uncommon (0.1<RA<1%), Common (1<RA<10%), Abundant (10<RA<20%) or Dominant (RA>20%). Coral diversity was calculated using the Shannon-Weaver index (H) and evenness index (E) (Ortiz-Burgos, 2016 ) The interpretation of the Shannon-Weaver index is that if H is a larger number, it is more diverse, and if E is closer to the value of 1, the species are more evenly distributed.

The biomass values of all fish were calculated using the length-weight relationship formula (Kulbicki et al., 2005 ) as follows:

W = a x L^b

Where “W” = weight (g); “L” = total length (cm); and “a” and “b” = constant.

The value of CHI for benthos was measured based on the proportion of live scleractinian coral cover and coralline algae over all substrates. The assessment of CHI for fish was measured by dividing the total fish biomass by the value of 500 g/m² (the maximum CHI value will be 1.0) (Kaufman et al., 2011 ).
The total 2D-CHI was then calculated based on the formula listed by Kaufman et al. (2011 ), as follows,

2D-CHI = [(CHI benthos + CHI fish)/2]

3. Results and discussion

3.1 Coral communities

A total of 22 transects were conducted within PPMP. The LCC of PPMP ranged between poor and fair conditions (20.00-49.69%) with an average value of 33.05 + 4.89% (Table 2). Out of 11 sites, sites K1 and L1 were categorized as having poor coverage of live corals, while others were in the fair category. No sites were categorized as good LCC. The S1 site of Pulau Segantang and the L1 site of Pulau Lembu had the highest and lowest values of LCC, with 49.69% and 20.00% respectively. S1 also had the highest percentage of non-scleractinian corals (27.67%). The average LCC value of 33.05% was considerably higher than the previous study in 2014 at PPMP by Khodzori et al. (2019 ) at 15.70%. However, the result was lower than the earlier study in 2001 by Toda et al. (2007 ) and the recent study in 2021 by DOFM (2022 ), which recorded LCC of 50.00% and 44.88% respectively. This result could suggest that the restriction of human activities in PPMP may be associated with a rise in the percentage of LCC. This could also result from survey differences between this study and Toda et al. (2007 ), Khodzori et al. (2019 ) and DOFM (2022 ), who only surveyed 2, 7 and 5 sites respectively.

Dead corals within PPMP had an average cover of 16.07%. The highest percentage of dead corals can be found at the P1 site of Pulau Payar and the K1 site of Pulau Kaca, with 28.35% and 25.32% respectively. Based on regular observations, both sites were considered favorite tourist spots for snorkeling and diving. The high proportion of dead corals in popular locations within MPAs could be related to human use. Maidin et al. (2022 ) stated that water-related tourist activities have been identified as among the major stressors in coral reef areas. The average cover of dead corals was lower than the previous study by Khodzori et al. (2019 ) at 16.50%. Jonsson (2002 ) reported that the dead corals percentage was inversely related to the LCC. Thus, the lower percentage of dead corals in this survey was supported by the higher percentage of LCC.

The present study recorded a total of 49 species, 30 genera and 14 families of scleractinian corals, and 7 genera of non-scleractinian corals in PPMP (Table 3). The total number of scleractinian coral species represented a large proportion of the 56 species that were documented by Waheed (2016 ) in the Straits of Malacca. The most common species recorded was Porites lutea, followed by Physogyra lichtensteini, a vulnerable species according to the International Union for Conservation of Nature’s (IUCN) Red List (IUCN, 2024 ). Porites lutea was the only species that was found at all sites. The dominance of Porites and Physogyra in PPMP was confirmed by Khodzori et al. (2019 ). Porites was also found to be dominant on Langkawi reefs (Jonsson, 2002 ; Ismail et al., 2022 ). Besides P. lichtensteini, five other vulnerable species were recorded, i.e., Duncanopsammia peltata, Pachyseris rugosa, Pavona decussata, Turbinaria mesenterina and T. reniformis.

Based on relative abundance (RA) values, Porites lutea was abundant at Pulau Payar, Pulau Kaca and Pulau Lembu, with 18.63%, 11.34% and 16.86% respectively. Physogyra lichtensteini was abundant at Pulau Payar (11.99%) and Pulau Lembu (11.66%). Dipsastraea favus was abundant at Pulau Kaca (10.13%), and Acropora grandis was dominant at the K1 site of Pulau Kaca. A rare species, Podabacia lankaensis, was uncommonly found on both the northern (P4) and southern (P2) tips of Pulau Payar (Figure 2). This species was previously recorded in the Andaman Seas (Ramakrishna et al., 2010 ). No record of P. lankaensis was reported in Malaysian waters (Waheed, 2016 ). However, because PPMP is located adjacent to the Andaman Seas, some other common coral species of the Andaman Seas can also be found in PPMP. This species inhabits shallow, horizontal, protected and partly turbid environments (Veron et al., 2011 ), which is the characteristic of sites P2 and P4. Seven non-scleractinian coral genera were also recorded, dominated by Rhodactis spp., particularly at Pulau Segantang (17.69%). Non-scleractinian corals were the most dominant coral type in Pulau Segantang, as reported by Sze et al. (2000 ). However, the total number of non-scleractinian coral genera recorded in this study (7) is relatively low compared to the 15 genera that were recorded by Mohammad et al. (2016 ). in the Straits of Malacca.

Diversity indices have often been used in coral reef studies and they have been recommended to complement the coral health assessment (Diaz-Perez et al., 2016 ). Generally, the higher value of the Shannon-Weaver index (H) corresponds to a higher diversity of coral communities. Coral diversity showed the lowest and highest H values of 2.03 and 2.98 at Pulau Lembu and Pulau Payar respectively (Table 4). The Pulau Payar diversity value was supported by the highest species richness with 37 species. Lower coral diversity has been related to a disturbed reef with a low value of LCC (Diaz-Perez et al., 2016 ).
Pulau Lembu had the lowest LCC of 25.13 + 5.13% (Table 2). This island is the closest to the mainland and is potentially more exposed to coastal development and sewage runoff from the mainland. Diversity is a function of evenness and richness, and these vary on a coral reef with sample size and location (Ismail et al., 2022 ). In terms of species evenness, the range of E between 0.75 and 0.85 showed that the corals of PPMP were very evenly distributed among the 49 species. In general, Pulau Payar had the highest value of species richness, the highest percentage of LCC and high value of E. This study categorized Pulau Payar as the most diverse and balanced coral reef ecosystem in PPMP.

Table 4. Diversity indices of scleractinian coral cover in PPMP.

Island	No. of Species	Shannon-Weaver Index (H)	Evenness (E)
Pulau Payar	37	3.01	0.83
Pulau Kaca	28	2.82	0.85
Pulau Lembu	15	2.03	0.75
Pulau Segantang	28	2.71	0.81
PPMP	49	3.14	0.81

3.2 Fish communities

From the fish survey, only 39 fish species, 23 genera and 16 families were recorded at PPMP (Table 5). Pulau Payar had the highest diversity of fish species while Pulau Lembu had the lowest diversity, with 30 and 16 species respectively. The total species observed was low when compared to earlier studies by Lee et al. (2005 ) and DMPM (2013 ), with 55 and 48 species respectively. However, the current number was higher compared to the 25 species recorded in the latest study at Pulau Payar by Ramli et al. (2016 ). The results clearly showed that, although the number of species was reduced over time, it had increased during the MCO. Somchuea et al. (2022 ) suggested that the sudden removal of human activities related to marine tourism had a positive effect on the numbers, density and species richness of the associated fish population.

None of the recorded fish were classified as endangered in the IUCN Red List of threatened species. Only one vulnerable fish species (Epinephelus fuscoguttatus) was found at the K2 site of Pulau Kaca. A hybrid grouper (Epinephelus sp.) was recorded in Pulau Segantang waters. However, it was not sighted at other islands of PPMP. This fish probably escaped from the off-shore cage culture in Langkawi and made Pulau Segantang its new home.

Family Serranidae had the highest number of species, followed by family Lutjanidae with 8 and 7 species respectively. Both families were targeted as food fish and were heavily fished due to their high commercial value. Therefore, changes in the abundance and sizes of these species observed gave an indication of the fishing pressure in the surrounding areas (Arai, 2015 ). Butterflyfish (family Chaetodontidae), which are often used as a biological indicator for coral health (Andersson, 2002 ), were observed in small numbers at all sites. Only 3 species of this family were found at PPMP, i.e., Chaetodon collare, C. octofasciatus and Heniochus acuminatus. The number of species in this family was very low compared to earlier studies by Andersson (2002 ) and Yusuf & Ali (2004 ), who recorded 7 and 16 species respectively. The abundance and number of species in this family were significantly correlated with the live coral cover, as many depend on the live coral cover for food and shelter Andersson (2002 ). The declining number of species may indicate that the corals in the area were degraded.

One of the more important variables of coral reef fish communities is the total biomass of targeted fish or commercially important fish, including herbivores and carnivores (Giyanto et al., 2017 ). The fish biomass at all 11 sites had values ranging from 19.56 g/m² to 182.62 g/m², with an average of 60.31 + 45.34 g/m². A similar range of fish biomass (11.18 g/m² to 193.62 g/m²) has been reported by Safuan et al. (2022 ) at Pulau Perhentian Marine Park, located on the east coast of Peninsular Malaysia. Site P2 of Pulau Payar presented the highest fish biomass (182.62 g/m²), contributed mainly by bigeye snappers (Lutjanus lutjanus). Family Lutjanidae contributed the highest fish biomass, with an average of 10.73 g/m², followed by Serranidae with 7.31 g/m². MacNeil et al. (2015 ) stated that coral reefs that maintained 500 kg of fish biomass per hectare (about 50% of an average reef's carrying capacity or about 50 g/m²) were found to maintain ecological functions while sustaining local fisheries, providing fishery managers with a critical target. With an average of 60.31 + 45.34 g/m² fish biomass, PPMP is “marginally sustainable”, but lower resilience could result in a shift of the fish community into an unsustainable situation.

Alias & Mohd. Saupi (2000 ) reported that members of the family Lutjanidae and Serranidae were among the key target fish caught by fishermen from the waters surrounding PPMP, giving an indication of spill-over effect by the marine park. The waters around these islands are important fishing grounds for both traditional and commercial fishermen from the mainland as well as from Langkawi. As mentioned by Andersson (2002 ), PPMP contributed to the recruitment and increased survival of fish before “exporting” them to the surrounding areas. However, there were no large species from the family Carangidae found in this study. Similarly, no sightings of any other large apex predators, such as sharks, give an indication of truncation of the trophic pyramid.

3.3 Two-Dimensional Coral Health Index (2D-CHI)

The results showed that two islands (Pulau Lembu and Pulau Segantang) had 2D-CHI values of less than 0.20 (very degraded), while Pulau Payar and Pulau Kaca had values of under 0.40 (degraded) (Table 6). The average 2D-CHI value of PPMP was 0.20, indicating that the marine park’s health was in a degraded condition. This 2D-CHI value was similar to the combination of CHI values for benthos and fish of Pulau Anak Datai, Langkawi, at 0.21 (Ismail et al., 2022 )

The 2D-CHI method has been successfully conducted in the western Caribbean (Diaz-Perez et al., 2016 ) and in Indonesia (Wulandari et al., 2022 ). Assessment based on benthic coverage and reef fish assemblages was considered an important standard for coral management in Indonesia (Giyanto et al., 2017 ; Wulandari et al., 2022 ).

Table 6. Summary of Coral Health Index calculations for benthos and fish.

Island	Benthos	Fish	2D-CHI	Status
Pulau Payar	0.33	0.15	0.24	Degraded
Pulau Kaca	0.29	0.11	0.20	Degraded
Pulau Lembu	0.24	0.11	0.17	Very degraded
Pulau Segantang	0.24	0.10	0.17	Very degraded
PPMP	0.28	0.12	0.20	Degraded

The low values of CHI at all islands indicate that the coral reefs of PPMP were in a stressed condition and can be categorized as unhealthy reefs. Although the current LCC value (33.05%) was categorized as “Fair” (26%-50%), the average CHI value was still in the lowest range of degraded condition (0.20-0.39). The risk is high for the reefs to become more degraded in the near future, unless the stress factor is minimized. Tourism impact has been documented as one of the main reasons for marine life and environmental degradation in MPAs (Ismail & Goeden, 2022 ). The overcrowding of tourists with uncontrolled diving, snorkeling and boating activities has been the main culprit in various accumulated negative impacts on coral reefs (Khodzori et al., 2019 ); Chuan et al., 2021 ; Maidin et al., 2022 ). Since its gazettement as a marine park in 1994, the number of visitors to PPMP has increased tremendously from about a thousand in the early years to over 100,000 tourists from 2013 onwards (Misni & Jarami, 2021 ). Thus, it is highly likely that the marine park has been subjected to excessive use, overcrowding and biological degradation.

The concept of resting periods could help coral reefs recover from constant stress and daily coral contact by tourists (Maidin et al., 2022 ). It has been suggested that the health of coral reefs can be improved by removing human pressure (Somchuea et al., 2022 ), even if temporarily. Thus, by adequately limiting the number of visitors to PPMP, the coral reefs of PPMP can be conserved and sustained.  Since this study was conducted during the Covid-19 lockdown, which has been reported to cause a significant reduction in anthropogenic activities at coral reef areas around the globe (Chuan et al., 2021 ; Edward et al., 2021 ; Somchuea et al., 2022 ), we believe that the brief closure might have at least a limited impact on the recovery of the coral reefs in PPMP.

Besides direct impacts from tourist activities, other anthropogenic disturbances such as coastal development, pollution and human-induced sedimentation were also among the factors that affected the growth of corals (Toda et al., 2007 ; Praveena et al., 2012 ; Safuan et al., 2021 ). The impact of coastal development might have been very minimal during the Covid-19 lockdown; however, sedimentation has always been a serious problem, particularly along the west coast of Peninsular Malaysia. The degradation of coral reefs has been linked with continuous sedimentation, especially in the Straits of Malacca (Praveena et al., 2012 ; Rudra, 2018 ). Understanding the major threats that affect the reef’s ecosystem is vital for improving the management of coral reefs (Safuan et al., 2021 ). Since this study was carried out during the MCO, the number of researchers was restricted by the local authorities for safety and security purposes. Hence, the number of studies was limited and the study sites were minimized.  We believe, in the future, that it is important to extend this study to assess the growth and survival of corals in relation to sedimentation, pollution and other aquatic environmental parameters caused by tourism activities.

4. Conclusions

This study was conducted during the “mandatory” MCO in response to the Covid-19 pandemic. Thus, this is the first published record of the effects of the MCO on the coral community of PPMP. Our identification at the species level makes this study the most comprehensive assessment of coral diversity in PPMP to date. We concluded that the coral reefs of PPMP were in degraded condition. Because the growth of corals is a slow process, recovery may require longer periods of protection than that afforded by the MCO. Our results can serve as up-to-date data for the benthic community structure of PPMP, and the impact of continuing tourism can now be investigated. It is also our hope that this information on coral health, using the CHI method, will be useful for sustaining the balanced use of resources at PPMP. Our future studies and way forward are to expand the implementation of CHI assessment to the whole coral reef ecosystem in Malaysia.

Acknowledgements

The authors would like to acknowledge Mr. Ahmad Ridzuan C. Nik for assisting during sampling activities and the authority of PPMP for permission and technical assistance.

Ethical statement

Not applicable.

Data availability statement

Data supporting these findings are available within the article or upon request.

Informed consent statement

Not applicable.

Conflict of interest

The authors declare no conflict of interest.

Author contributions

Ismail MS: conceptualization, methodology, investigation, formal analysis, writing original draft, review and editing. Ilias Z: methodology, investigation, formal analysis, writing review and editing. Ismail MN: investigation, formal analysis, writing review and editing. Khoo ML, Goeden GB and Yap CK: writing review and editing.

Funding

The research work was funded by the 2020 and 2021 development budgets (P21-30701011-30004017-0302) from the Department of Fisheries, Malaysia.