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Nature and Management of Some Marine Ecosystems in Vietnam: A Case Study at The Hon Mun Island at Nha Trang | OMICS International
ISSN: 2157-7625
Journal of Ecosystem & Ecography

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Nature and Management of Some Marine Ecosystems in Vietnam: A Case Study at The Hon Mun Island at Nha Trang

Sarfo Isaac1* and Terney Pradeep Kumara2

1Marine Ecosystem Mgt and Climate Change, Nha Trang University, Vietnam

2Department of Oceanography and Marine Geology, University of Ruhuna, Sri Lanka

*Corresponding Author:
Isaac S
Marine Ecosystem Mgt and Climate Change, Nha Trang University, Vietnam
Tel: +841223812106

Received Date: July 19, 2016; Accepted Date: August 30, 2016; Published Date: September 05, 2016

Citation: Isaac S, Kumara TP (2016) Nature and Management of Some Marine Ecosystems in Vietnam: A Case Study at The Hon Mun Island at Nha Trang. J Ecosys Ecograph 6: 208. doi:10.4172/2157-7625.1000208

Copyright: © 2016 Isaac S, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Visit for more related articles at Journal of Ecosystem & Ecography


Nha Trang is a city in Vietnam endowed with several sceneries which has attracted several tourists around the world over the past few decades. The city is highly characterized by coastal features as well as beautiful landscapes. Among these features are; beaches, caves with swift-let birds, resort centers, islands, traditional temples, forts and so on. The act of enhancing economic activities, coupled with some natural factors like; climate change as well as the increasing number of tourists’ over the years has led to the alteration of some of these ecosystems, that gives the city its value, hence, sense of attracting numerous tourists from all walks of life. The Hon Mun Islands are located to the south of Nha Trang Bay. Hon Mun MPA is situated in central - South Vietnam, offshore from the coastal resort city of Nha Trang, Khanh Hoa Province. The name “Hon Mun” (means Black Island) comes from the high and rugged cliffs forming up caves, particularly black rock here as ebony, very rarely seen elsewhere. Due to the island’s location adjacent to the hot sea-currents from the equator, suitable to the development conditions of corals and various types of tropical sea creatures, the sea bed of Hon Mun is home to an abundant and diverse group of marine species, an interesting and useful place for researchers, oceanographers and tourists to observe and explore more of the sea creatures’ life [1]. It is for these reasons why this study was conducted to delve into the nature, management and threats posed on the ecosystems at the Hon Mun Island at Nha Trang in Vietnam.


Hon Mun; Biodiversity; Management; Transect; Coral reef; Island

Lifeform Codes

STN: Stone; SND: Sand; R: Rubble; ODC: Old Dead Coral; FAV; Favia species; MON: Montipora species; GAL: Galaxea species; ACR: Acropora species; FUN: Fungia species; POR: Porites species; POD: Podabacia species; TUB: Tubastrea species; POC: Pocillopora species


The International Union for Conservation of Nature (IUCN) defines a marine protected area as: “a clearly defined geographical space, recognized, dedicated and managed, through legal or other effective means, to achieve the long-term conservation of nature with associated ecosystem services and cultural values”. This study conducted to undertake line transect measurement in two different sites at the Hon Mun Island, to make some observations on some bottom features, coral reef types and their habitats, zonation, the nature and management of ecosystems at the Hon Mun Island at Nha Trang.

In recent years, with increasing economic development, the marine environment adjacent to Nha Trang City, especially around the Hon Mun Islands, has faced increased exploitation. Coral reefs have been destroyed by many, mainly human-induced, factors. Shipping, dynamite-fishing, coral harvesting and marine tourism have led to a decrease in marine biodiversity and the loss of precious genetic resources, such as those of the Hawksbill turtle, false killer whales and leatherback turtles, from the South China Sea. Destructive activities obviously diminish the benefits reaped from tourism in the islands [1,2]. It is for these reasons why this study was conducted to explore more the nature, management and threats posed on the ecosystems at the Hon Mun Island at Nha Trang in Vietnam.


The main objectives of this study were to:

1. Give an overview of the current status of biodiversity at the Hon Mun Island and its marine environment

2. To briefly analyze data using Line transect measurement of some diversity in the area

3. To give a general view on how the island is being managed

4. Identify key problems affecting biodiversity at the Hon Mun Islands

5. Propose measures to mitigate these problems

Study Area

The Hon Mun Islands are located to the south of Nha Trang Bay. The total area of the complex is about 160 km2, in which 122 km2 is sea and 38 km2 is an island area. Since 1975, the National Marine Programme of Vietnam, which was implemented by National Centre for Natural Science and Technology, has run at Hon Mun to analyze and preserve marine creatures here. Currently, Hon Mun is a famous attraction in Nha Trang for Vietnamese and tourists [1]. The islands have a variety of habitats and ecosystems, including fringing coral reefs, mangrove forests and sea grass beds with an adjacent deep-water upwelling, which supports the local fishing industry. Hon Mun MPA is situated in central - South Vietnam, offshore from the coastal resort city of Nha Trang, Khanh Hoa Province. The MPA encompasses nine islands (Hon Tre, Hon Noc, Hon Mun, Hon Rom, Hon Vung, Hon Cau, Hon Mot, Hon Tam and Hon Mieu) and their surrounding waters, some 160 km2 in total [3]. The nine islands, located from 1 km to 15 km offshore, provide the topographic basis for a wide range of coastal and marine habitat types, developed in relation to prevailing oceanographic conditions and gradients in mainland - oceanic influences (Figure 1). The diverse array of tropical habitats includes coral reefs, soft bottom communities, sea grass beds, mangroves, sandy beaches and rocky shores.


Figure 1: A map showing the Hon Mun Island (Source: Google map).

Materials and Methods

Materials for data collection

Use of cellular phones, measuring tape for transects measurement, ruler, slate, pencil, thread and snorkeling masks.

Methods for data analysis

Personal and direct observations were made at the study area. Informal interviews were conducted with some personnel at the area to get more insight about the area. Secondary data from the internet and other literature were used to give detailed information on biodiversity of species and management of the ecosystem at the Hon Mun Island. Use of Microsoft office tools like; Microsoft word and excel worksheet as well as Shannon Weiner’s index to calculate for the diversity of species in the area in quantitative analysis and formulation of charts.

Research strategy

The strategy used for this research was both qualitative and quantitative approach. Some quantitative tools were used in the collection and analyzing of data. No laboratory test or analyses were made to establish a logical base except quantitative tools outlined in section 6.2.

Research design

The research design adapted for this study is a case study design. A single case study was adapted to explore more about the nature and management of ecosystems at the Hon Mun Islands, taking into consideration some areas that were measured for this study. Since, this study is a single case study, results or findings cannot be generalized for the entire islands in Vietnam or other islands at Nha Trang.

Limitation of the study

Limited funds did not enable us to visit the place more often to engage the most of the local people who are mainly farmers and fishermen, thus, participatory/action based research to delve more and broaden the objectives of this study. This limitation does not limit the validity and credibility of this study since, engagement of the people is not a main objective although it would have helped establish and give us more information. Language barrier also hindered our ability to engage most of the indigenous or local inhabitants although the primarily mode of data collection was through primary data as well as use of secondary data on the internet and from the site as well as engaging some few staff at the site.



(Tables 1-6) In calculating for the variables in the tables above; Difference in transitional Life-formCode in the area measured by the Lifeform at that given area up to the next area or zone being measured. Hence, zones with the same life-form have their distance summed up (i.e., Sand (SND) covered in two or three areas are summed up; L1i+L1ii….L1n). Using Shannon Weiner’s mode of calculating for diversity of species in a given area;

Description Hon Mun Island
Corals reefs cover √√√
Coral reefs structure √√√
Recreational activities √√√
Organisms √√√
Rocks √√
Sand beaches √√
Jelly Fish x
Sea urchins √√
Swiftlet birds x
Swiftlet nest x
Sea star √√
Boats √√√
Snorkeling √√√
Tourism √√√
Sea cucumber x
Diving √√
Water Clarity
Fishing activities x
Sea turtles x
Shore Constructions
Limpets √√
Tropical Periwinkles (Ligia sp.) √√

Table 1: Visual observation for the two islands (√√√ = Good, √√ = Fair, √ = Poor and x = none).

  No. of known species
Coral 193
Fish 176
Crustaceans 112
Echinoderm 27
Molluscs 112
Algae 104

Table 2: Biodiversity of species at the Hon Mun Island at Nha Trang.

Transition (cm) Lifeform Code Difference In Transition (cm)
0-50 STN 50
50-250 SND 200
250-400 R 150
400-432 FAV 32
432-752 SND 320
752-813 ODC 61
813-913 MON 100
913-970 GAL 57
970-980 ACR 10
980-1200 SND 220
1200-1210 FUN 10
1210-1390 STN 180
1390-1420 FAV 30
1420-1463 POD 43
1463-1500 POR 37
1500-1713 SND 213
1713-1800 MON 87
1800-1925 SND 125
1925-2000 TUB 75
  TOTAL 2000

Table 3: Line transect measurement for species diversity and the transition of Lifeforms at Site A.

LIFE-FORM CODE % Cover (%) Total of Diff. In Lc Area Covered (Cm) Pi In(Pi) Pi*In(Pi)
STN 11.5 230 0.115 2.16282 0.24872
SND 53.9 1078 0.539 0.61804 0.33312
R 7.5 150 0.075 2.59027 0.19427
FAV 3.1 62 0.031 3.47377 0.10769
ODC 3.05 61 0.0305 3.49003 0.10645
MON 9.35 187 0.0935 2.36979 0.22158
GAL 2.85 57 0.0285 3.55785 -0.1014
ACR 0.5 10 0.005 5.29832 0.02649
FUN 0.5 10 0.005 5.29832 0.02649
POD 2.15 43 0.0215 -3.8397 0.08255
POR 1.85 37 0.0185 3.98998 0.07381
TUB 3.75 75 0.0375 3.28341 0.12313
TOTAL 100 2000  

Table 4: Percentage cover (Life-forms) and use of Shannon Weiner’s index to measure species diversity at Site A.

Transition(cm) Transition Difference in Transition (cm)
0-50 POC 50
50-73 TUB 23
73-123 POC 50
123-300 SND 177
300-425 POC 125
425-433 FAV 8
433-444 MON 11
444-514 POC 70
514-900 STN 386
900-911 GAL 11
911-1024 POC 113
1024-1133 ACR 109
1133-1333 POC 200
1333-1453 SND 120
1453-1540 POC 87
1540-1544 FUN 4
1544-1654 POC 110
1654-1727 SND 73
1727-1800 POC 73
1800-1914 FAV 114
1914-1994 POC 80
1994-2000 POD 6
  TOTAL 2000

Table 5: Line transects measurement for species diversity and the transition of Life-forms at Site B.

LIFEFORM CODE % Cover (%) Total of diff. in lc area covered Pi In(Pi) Pi*In(Pi)
POC 47.9 958 0.479 0.73605 0.35257
TUB 1.15 23 0.0115 4.46541 0.05135
SND 18.5 370 0.185 -1.6874 0.31217
FAV 6.1 122 0.061 2.79688 0.17061
MON 0.55 11 0.0055 5.20301 0.02862
STN 19.3 386 0.193 1.64507 -0.3175
GAL 0.55 11 0.0055 5.20301 0.02862
ACR 5.45 109 0.0545 2.90955 0.15857
FUN 0.2 4 0.002 6.21461 0.01243
POD 0.3 6 0.003 5.80914 0.01743
TOTAL 100 2000  

Table 6: Percentage cover (Life-forms) and use of Shannon Weiner’s index to measure species diversity at Site B.


In (Pi) = Natural log (LN) of value attained for Pi for a given Life-form Code

H (Index) - Σ (Pi*In (Pi)) of all Life-form Codes covered in the area

H (Max) - In (Total Area/Distance covered)


Where E=1(Perfect or wide variety of species in the area)

0.5≥ E<1 (Fair)

E<0.5 (Limited number/variety of species in the area)

Management of ecosystem at the Mun Island

In an interview with a tourist guide at the Hon Mun Island, we were meant to understand that the site is being managed by the Government of Vietnam with sole responsibility given to the Ministry of Fisheries as the responsible agency. Khan Hoa PPC and the committees in some allocated communities or villages around the Hon Mun Island.

There are some forms of international support for management of Hon Mun Island from the World Conservation Union supporting the Marine Protected Area, funded by Global Environmental Facility (GEF) through the World Bank as well as the Royal Danish Government through DANIDA [4].

Objectives of Hon Mun marine protected area

• To conserve a representative example of internationally significant and threatened marine biodiversity.

• To enable local island communities to improve their livelihoods and in partnership with other stakeholders to effectively protect and manage the marine biodiversity at Hon Mun as a model for collaborative marine protected area management.

Enforcement plan: The enforcement plan is aimed at eliminating illegal fishing in the area which destroys fish larvae and coral reefs, as well as enforcement of gear and no fishing restricted zones. Some zones have been demarcated for snorkeling, diving, boat settlement and so on, basically recreational activities [5] in the area. Marine protected areas village committees liaising with personnel from the government.

All stakeholders have been brought on deck to help manage the Hon Mun Island. Village committees have been set up in each village to represent the interest of their people, teaming up with Mun Island MPA Authority as well as provincial agencies in management of this zone.


Line transects measurement of species at Site A and Site B

The survey was conducted to measure diversity of species at the bottom zone at the Mun Island as well as to enable students to describe reef habitats. Per direct observation, some features which were found in the area can be classified into these (Table 7).

Living biotic features Substrata Others
Lively hard corals Sand Geomorphology
Soft corals Bedrock Visibility
Macro algae Rubble Depth  
Sponge Dead coral  
Some fish species
Echinoderms like; sea urchins, star fish and so on

Table 7: Biotic and abiotic features at these two sites.

Per the tables, thus, Tables 3-6 outlined in the results of this study for the two given sites, it can be concluded that, both sites have limited variety of species in this ecosystem. Per Shannon Weiner’s index of measuring species diversity in a given area, thus, equitability (E*), when E* is 1, means there are wide range of species in that area. Half this value means there are fair or moderate variety of species in the area. Before this value (E* <0.5) means limited diversity of species in an area. At site A, E* was calculated to be 0.2165 whereas at Site B, E* was calculated to be 0.19075 [6]. Hence, per these two given values which were being calculated from the data gathered from these two sites, we can logically state that, there are limited diversity of species, specifically, the life-forms in those two given areas or sites as well as other species which may be in the same group or family with these life forms outlined in Tables 4 and 5 but may not be available in these two areas.

Biodiversity of species at the Hon Mun Island

With reference to the tables illustrated above, it can be observed that, there is a wide range of species at the Mun Island from site report and per direct observations made ranging from fishes, crustaceans, echinoderms, molluscs, algae and corals as well as vegetative cover around the ocean with variety of birds and other terrestrial insects and animals.

The main objective of this study was to expose students to biodiversity of species at the site and to take transect measurement in shallow zones of the ocean where there are coral reefs, sand and rocky zones coupled with other species.

Coral reefs at the Mun Island

There were wide ranges of coral reef forms ranging from encrusting, columnar, plate-like, mushroom (Fungia sp.), free living, massive, semimassive and branching corals. These coral forms had several polyp growth forms like; plocoids, phaceloid, ceroid, meandering and flabellomeandroid growth forms embedded around them when observed from above (Figure 2).


Figure 2: Coral reefs at the Mun Island (Source: Field Data/Survey).

Coral reefs as a base for protection and habitat for some fishes, echinoderms, crustaceans and molluscs

Per direct observation, some dead corals, broken (fragmented) corals in a state of bleach with some still growing as well as a coral with half of its section being dead and half being alive in the images below (Figures 3 and 4).


Figure 3: Coral reefs as a base for protection and habitat for some fishes, echinoderms, crustaceans and molluscs (Source: Field Data/Survey).


Figure 4: Observation of some dead corals, broken (fragmented) corals in a state of bleach with some still growing as well as a coral with half of its section being dead and half being alive (Source: Field Data/Survey).

Threats/Problems the Hon Mun Island is faced with:

Over-harvesting of resources: Overfishing may cause algae bloom since some of these fishes feed on algae and when harvested excessively may increase the accumulation of algae. In addition is harvesting corals for making jewelries and other ornaments.

• Illegal fishing

Tourism and other recreational activities like; diving, snorkeling and trampling, touching or walking on coral reefs by some tourist as well as anchor damage from boats especially during low tide zones (Figure 5).


Figure 5: Threats/Problems the Hon Mun Island is faced with.

• Pollution: Some forms of solid waste like; clothes, baskets, old fishing nets and polythene bags were found beneath the ocean where there are coral reef platforms from direct observation. This goes a long way to breed algae and compete for space with corals (Figure 6).


Figure 6: Observation of solid waste like; clothes, baskets, old fishing nets and polythene bags were found beneath the ocean (Source: Field Data/Survey).

• Inputs from land like; nutrients and sediment run off from agricultural lands around the island or from mountainous farmlands. This causes smothering and growth of algae competiting with the corals (Figure 7).


Figure 7: Observation of inputs from land like; nutrients and sediment run off (Source: Field Data/Survey).

Invasion of some species thereby causing some corals to die off or bleach: e.g. Crown-of-thorn on some corals with some images captured from field study (Figure 8).


Figure 8: Invasion of some species thereby causing some corals to die off or bleach.


These are some measures which when effectively taken into consideration, can ensure sustainable use of resources at the Hon Mun Island:

1. Participatory planning and management by relevant stakeholders.

2. Development of alternative income generating activities to draw people away from activities associated with excessive resource use.

3. Capacity building through management training and public education. A tourist who visits this site are being sensitized, fishermen, local people in the area are being educated about the need to conserve the resource and how their actions can significantly impact upon the resources in the area.

4. Monitoring and evaluation of how effective policies, plans and programs which have been implemented are meant to conserve or keep the resources in its pristine nature.

5. Support community involvement through; Collection of user fees of which a percentage is returned to local communities. Local people are involved in monitoring the change in biodiversity. Local people are rewarded for improvements in the local marine environment.


In nut-shell, participatory or action based approach as well as conservation, are two main approaches, which can be adhered to ensure sustainable use of resources if the right policy framework and monitoring mechanisms are properly structured through institutional capacity [7]. The factors spelt above delves into biodiversity of species at the Hon Mun Island, who manages the site, support, threats which degrade the site’s pristine ecosystem and proposed measures which can be adapted to ensure sustainability of resources in that marine environment.


We would like to express our profound gratitude to God Almighty for giving us strength to embark on this study thereby making this study fruitful. We would also like to thank the management at the Hon Mun Island for their time and information they gave to us as well as Norhed and management of Nha Trang University for the resources they provided in making this study a success.


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