Journal of Environmental Treatment Techniques  
2020, Volume 8, Issue 3, Pages: 1220-1224  
J. Environ. Treat. Tech.  
ISSN: 2309-1185  
Journal web link: 10.47277/8(3)1224  
Diversity of Molluscs (Gastropod And Bivalve) In  
Mangrove Ecosystem of Oransbari District, South  
Manokwari Regency, West Papua Province,  
Markus Waran , Marlon I. Aipassa , Jacob Manusawai , Anton S. Sinery  
PhD student of environmental sciences programs of Papua University  
Postgraduate programs of Papua University  
Forestry Faculty of Mulawarman University  
Environmental Research Centar of Papua University, Indonesia, Amban Manokwari 98313  
Received: 07/06/2020  
Accepted: 30/07/2020  
Published: 27/07/2020  
In the Oransbari mangrove ecosystem, 13 species of molluscs were identified with 1256 individuals consisting of 9 species of  
gastropod and 2 species of bivalve. Dominance index of the identified molluscswas 0.11, with species diversity index of 1.89 (medium  
category) and species evenness index of 0.76 (high category).  
Keywords: Diversity, Molluscs, Gastropod, Bivalve, Mangrove Ecosystem, South Manokwari  
through the revised of West Papua spatial planning document  
1). According to (1), West Papua currently has 39% of marine  
Mangrove in South Manokwari Regency is one of the  
protected area and 55-60 % of terrestrial protected area, in the  
revised of West Papua spatial planning 2013-2033.  
potential mangrove ecosystems that could be intensively  
managed by local government to support the sustainable  
development goals. This is based on change of function of forest  
area for development and optimization of the environmental  
quality index through efforts to increase the area of protected  
areas to 47% (41,691 ha) from the current condition of 46%  
Molluscais a group of organisms that play an important role  
in ecosystem mangroves, as it is often used as environmental  
bioindicator. According to researchers mollusca is the second  
most common phyla after Arthropods consisting of  
Polyplacophora (chitons), Gastropods (snails), Bivalvia (clams),  
Scaphopods (hornshells), Cephalopods (squid or octopus),  
Aplacophora and Monoplacophores and Monoplacopora. From  
those seven classes, Gastropoda and Bivalvia are considered as  
the largest classes of molluscs (2). Both of them play an  
important role in ecology (the food chain), as well as in  
supporting the economic life of the coastal community.  
Mangrove gastropods are detritus-eaters that play a role in  
breaking down fresh litter, as well as accelerating the process of  
litter decomposition by microorganisms (3). According to (3),  
molluscs are beneficial to humans including as a source of  
protein, animal feed ingredients, industrial materials, jewelry,  
fertilizer materials and medicines. For instance, several species  
of molluscs such as Terebralia palustris, Telescopium  
telescopium, Cerithidea obtusa (3). Moroever, some speciessuch  
as Anadara granosa, Gelonia erosa, Anadara pilula, Gelonia  
(41,306 ha). Besides, as an effort to maintain mangrove  
ecosystem related to its function as a buffer against abrasion and  
tsunami, the habitat of various types of aquatic biota, mangrove  
also plays an important role in community livelihood through  
the utilization of aquatic biota, especially fish, crabs, shrimp and  
Management of mangrove ecosystem in Oransbari district is  
applied through the intensive management plan of the Oransbari  
mangrove forest area in order to particularly support the area of  
West Papua mangrove forests 4.81% (4,791.29 km ) of total  
area as well as to maintain in general the Indonesia mangrove  
forests which reaches 3.2 million ha (22,4%) of world. The  
target plan is ongoing with the commitment of maintaining 39%  
of marine protected area and 57% of terrestrial protected area  
Corresponding author: Anton S. Sinery, (a) Postgraduate  
programs of Papua University and (b) Environmental Research  
Centar of Papua University, Indonesia, Amban Manokwari  
Cerithideopsilla cingulata are generally consumed by coastal  
communities, especially in the regions of Papua and West  
Oransbari mangrove ecosystem with total area of 384,9 ha is  
Journal of Environmental Treatment Techniques  
2020, Volume 8, Issue 3, Pages: 1220-1224  
one of the mangroves in the region that has potential flora, fauna  
and ecosystem services that are worth to be developed. One of  
mangrove potencies is molluscs species, especially gastropod  
and bivalve which have ecological and economic importance for  
the ecosystem and coastal community. According to interview  
and field observation, there are several types of molluscs in this  
region, but they are not yet scientifically identified. Therefore,  
the research aims to identify types of molluscs particularly  
species of gastropod and bivalve in Oransbari mangrove  
number of individuals of all species.  
Dominationisa community characteristic that shows the  
abundanceof species in a region (Odum, 1971 in 13). The  
criteria of domination index according to Odum (1993) are: 0  
<C <0.5 = Thereare no dominant species; 0.5> C> 1 = Thereare  
dominant species. To determine the diversity of mollusca as an  
indicator of habitat, species index diversity (H) according to  
Shanon and Wiener (1949) in (13) was used with the equation:  
H    
N   
Material dan Methods  
This research was conducted in mangrove ecosystem of  
Oransbari district, South Manokwari Regency, West Papua  
Province, Indonesia. The study was done for two months from  
January to February 2020. The equipments used consisted of  
GPS (Global Positioning System), levers, plastics, collection  
bottles, tweezers, digital camera, vernier caliper, surgical boards,  
gauges, raffia and stationery. The materials used were label  
paper and alcohol 70%and formalin.  
The research was using descriptive method with observation  
techniques. The observation station was determined using  
purposive sampling which isconsidering the zonation of  
mangrove vegetation. The Oransbari mangrove ecosystem  
Note: H = diversity index (Shanon-weinner index); ni =  
Number of individuals of a species, N = Number of individuals  
of all species. Shanon and Wiener (1949) in (13), species  
diversity was considered high if the species diversity index was  
more than three (H≥3), medium if species diversity index was  
between one to three (1 <H <3) and low if species diversity  
index was less than one (H <1). The evenness of species of  
mollusca at the study site was analyzed using the index of  
evenness (e), according to (13) as follows:  
e   
hasspecies relatively similar with  
forest width of  
LogS Hmax  
approximately 120-1000 m. Consideringthe condition, the  
observation sites (sampling stations) was determined in one  
transect 120 m long dominated by Sonneratia sp, Rhizophora sp,  
Avicennia sp, Bruguera gymnorhiza. Each site had four  
obsevation plots with size of 10 m x 10 m.  
Hmax 2 lns  
Note: e = species evenness index; H = species diversity  
index; S = Number of species. Evennessindex according to  
Krebs (1985) in (14) ranged from 0-1, where: 0.6-1 = high  
species evenness; 0.4 <e <0.6 = moderate species evenness; 0–  
04 = low species evenness.  
The main variables observed were morphological characters  
of mollusca (gastropod and bivalve) in form of color, body size  
(length, width, diameter expressed in cm) in order to determine  
the species and number of individuals. Moreover, general  
condition of study site was documented. Collecting samplesof  
molluscs (gastropod and bivalve) weredone at low tide and in  
sunny day. The samples on substrate and attached to mangrove  
roots (inside the plot) were taken entirely. The collected samples  
thus were preserved using alcohol 70% and put into specimen  
box. Furthermore,the samples were identified using the journal  
3 Results and Discussion  
.1 Species Composition  
Based on the identification of the morphological  
characteristics of the mollusca body, 13 species of molluscs  
were identified, consisting of 7 families and 9 species of  
gastropod, 2 families and 4 species of bivalve (Table 1). The  
result as shown in Table 1 showed that the composition of  
molluscsfound in Oransbari mangrove ecosystem was smaller  
compared to (15) there were 30 species found in Tanjung Jara,  
Terengganu beach, Peninsular Malaysia, 11 species were found  
in Northeast Algeria (16), 15 species were found in the  
mangrove ecosystem of Lubuk Kertang village, North Sumatra  
(17), 65 species were found in the waters of Ambon Island,  
Indonesia (18), (12) which identified 75 species of gastropod  
and 19 species of bivalve in South Biak Papua. (11) found 14  
species of gastropod and 1 species of bivalve in mangrove forets  
of Dedap Village, Tasikputripuyu Kepulauan Meranti regency in  
Riau Province. (10) recorded 15 species of gastropod in TPI  
Parit 7, Tungkal I village, West Tanjung Jabung and 16 species  
of gastropod in the mangrove forests of Teluk Awur Jepara (19),  
4), (5), (6), (7), (8), (9), (10), (11), (12). The collected data were  
analyzed qualitatively and quantitatively based on each  
parameter and therefore presented in tables and figures (charts,  
graphs and photographs). To determine the abundance of species  
in the area, the equation was used as follows:  
A   
Note: A = Abundance (number of individual / 20m2); xi =  
number of individuals; ni  
= Number of squares. The  
concentration of individual species of mollusca wasdetermined  
usingindex of domination (C) (Simpson, (1949) in (13) as  
20) reported 33 species of gastropod in the mangrove  
ecosystem in the Gugus Pari Island, and 29 species of gastropod  
in the mangrove forest area of Segara Anakan Cilacap (21).  
Many speciesof gastropod were found in those studies due to the  
wider research location and longer sampling time. While in this  
research, the location of the research was small, the sampling  
ni   
C    
N   
Note: C = index of dominance; ni = number of individuals of  
Journal of Environmental Treatment Techniques  
2020, Volume 8, Issue 3, Pages: 1220-1224  
time was limited and many species have been hunted by local  
people for consumption purpose.  
Table 1: Composition of Molluscs in the Oransbari Mangrove  
Indiv Percent  
idual (%)  
Nerita articulata, Gould, 1847  
Terebralia palustris Linnaeus,  
192 15,29  
161 12,82  
Potamididae Cheritidea sp  
149 11,86  
143 11,39  
141 11,23  
Figure 1: Domination index (C), diversity index (H) and evenness index  
Monodonta sp  
Nerita signata, Lamarck, 1822  
(e) of molluscs species in the Oransbari mangrove ecosystem  
Littorinidae Littoraria scabra Linnaeus, 1758 125 9,95  
The result showed that diversity index of mollusca in the  
Oransbari mangrove ecosystem was 1.89. The study found  
species diversity of sitewas considered in the medium category.  
According to (13), species diversity was consideredhigh if the  
species diversity index was more than three (H≥3), medium if  
species diversityindex was between one to three (1 <H <3) and  
low if species diversityindex was less than one (H <1). Based on  
these criteria, the diversity of species of mollusca in the  
Oransbari mangrove ecosystem area was belong to medium  
category. (13) assertedthat a communitywould havehigh species  
diversity if the community was composed of many species with  
the similarabundance or almost the same. Conversely, if the  
community was composed of several species and if only a very  
few species were dominant, then the species diversity was low.  
In addition, (22) stated that the level of species diversity could  
describe the stability of ecosystem, when the diversity of species  
in an area is higher, the ecosystem tends to be more stable and  
it would develop interaction of species which could involve  
transfers energy, competition and more complex division of  
Analysis of species evenness level showed that value of  
evenness index of mollusca species in Oransbari mangrove  
forest was 0.76. (13) stated that the evenness value was  
considered high when e ≥ 0.6, moderatewhen e = 0.4 <e ≤0.6  
and low when e = 0 <e ≤ 0.4. Based on the criteria, the evenness  
index of mollusca in the Oransbari mangrove forest