Journal of Environmental Treatment Techniques  
2020, Volume 3, Issue 3, Pages: 1176-1181  
J. Environ. Treat. Tech.  
ISSN: 2309-1185  
Journal web link: http://www.jett.dormaj.com  
Diversity of Gastropod and Bivalve Molluscs in  
Kaisu Mangrove Forest of Sarmi Regency, Papua  
Province, Indonesia  
*
Jacob Manusawai , Anton S. Sinery, Rina N. Jowey  
Department of Environmental Science, Universitas Papua, Indonesia  
Received: 13/05/2020  
Accepted: 22/07/2020  
Published: 20/09/2020  
Abstract  
Molluscs are an important part of the mangrove ecosystem. Scientific information related to gastropods and Bivalvia in Kaisu  
mangrove is not known. Thus, this study aims at identifying the diversity of molluscs (gastropod and Bivalvia) in Kaisu mangrove forest.  
This study has used descriptive method with observation techniques. The observation station was determined using purposive sampling  
considering the zonation of mangrove vegetation. The taken data were analyzed qualitatively and quantitatively based on each parameter.  
The results of the study show that, in Kaisu mangrove forest of Bongga District, Sarmi Regency, 10 species of molluscs were identified  
with 1804 individuals consisting of 8 species of gastropoda (Telescopium telescopium, Steno melani, Nerita articulate, Ellobiumaurisjudae,  
Cheritidea obtuse, Indothais gradate, Spherassimineamimata, Littorariamelanostoma) and 2 species of Bivalvia (Geloinaexpansa,  
Anumalocardisquamasa). The dominance index of the mollusca species of this mangrove forest was 0.74, indicating the dominance of  
Telescopium telescopium with species diversity index of 0.27 (low category) and a species evenness index of 0.32 (low category).  
Keywords: Molluscs; Bivalvia; Mangrove forest; Ecosystem  
Introduction1  
(
squid or chiton), Aplacophora and Monoplacopora. Bivalves  
1
play a vital role in the ecosystem of mangrove forest and in the  
lives of coastal humans (9). Bivalve molluscs are a valuable  
source of high-quality proteins, minerals and vitamins (10).  
Crustaceans and molluscs play important roles in the  
mangrove ecosystem, processing mangrove-derived and algal  
detritus through their feeding and bioturbation activities (11).  
According to Pramudji (12), Mollusca-inhabiting mangrove  
forests in Indonesia are generally dominated by gastropods,  
which are around 61 species. Gastropod in mangrove  
ecosystems has both ecological and economical significances.  
Gastropod (limpets, snails, whelks, slugs) is by far the most  
diverse group of molluscs with about 100,000 species (0.5 mm  
to 100 cm long) that inhabit all marine, freshwater and terrestrial  
habitats (13). From ecological perspective, gastropod is a type of  
fauna that have a role in a food chain. Gastropods are detritus-  
eaters that have function in tearing and minimizing newly fallen  
litter, and accelerating litter decompositions through  
microorganisms (12), (14). Gastropods have economic value as  
they are used by coastal community as food, for instance,  
The main text of the article should appear here. Headings  
and subheadings should be formatted using the relevant button  
from the “Apply Style” dialog box. Mangrove plays an  
important role in the lives of wildlife including birds, mammals,  
reptiles, fishes and other organisms such as mollusks (1). It is a  
biologically diverse ecosystem, rich in organic matter and  
nutrients, and supports a large biomass of flora and fauna (2). It  
is considered among the world’s most productive ecosystems  
(3). High rates of tree and plant growth, coupled with anaerobic,  
water-logged soils that slow decomposition, result in large long-  
term carbon © storage within the mangroves (4). From an  
economic point of view, mangroves have a very high economic  
and ecological value because of the wide range of ecosystem  
goods and services they offer (5).In addition, mangroves also  
perform, free-of-cost, many important functions that support the  
often-dense coastal populations (6). Molluscs are the second  
species-rich phylum in the world after arthropods (7). They are  
soft-bodied, unsegmented animals, with a body organized into a  
muscular foot, a head, a visceral mass containing most of the  
organ systems, and a fleshy mantle that secretes the calcareous  
shell(8). According to Brusca & Brusca (9), Mollusca consists of  
seven classes, namely Polyplacophora (chiton), Gastropod  
Terebraliapalustris,  
Telescopium  
telescopium,  
and  
Cerithideaobtusa (14). The total area of mangrove forests in  
Papua Island, including Papua and West Papua, is estimated to  
reach 1.3 million ha (1). The mangrove areas in Papua covers  
the North and South coasts of Papua Island, SaireriBay,  
Mamberamo River, HomblotBay, Wasoki Bay, Ansus, the  
Eastern part between Biak and Yapen Islands. In the Southern  
Part of West Papua, mangroves flourish along the Waigeo coast  
(snail), Bivalvia(clam), Scaphopoda (hornshell), Cephalopoda  
Corresponding author: Jacob Manusawai, Department of  
Environmental Science, Universitas Papua, Indonesia. E-mail:  
dr.jacob.manusawai@gmail.com  
1
176  
Journal of Environmental Treatment Techniques  
2020, Volume 3, Issue 3, Pages: 1176-1181  
and the northern part of Barai peninsula around Bintuni Bay;the  
mangroves in Bintuni are the most significant ecosystem in  
storing large amounts of carbon (15).  
2
where A is abundance (number of individual / 20m ); xi is  
number of individuals; and ni is number of squares. The  
concentration of individual species of Mollusca was determined  
using index of domination (C) as followed:  
Sarmi Regency has several locations of mangrove forests  
distribution, including along the East coast. The distribution of  
mangroves in the area is not only potentially related to  
ecological function but also related to the socio-economic  
conditions of the community. Ecologically, mangrove forest has  
an important role as a buffer zone which protects the coast from  
Pacific Ocean waves. Mangroves play an important role in  
buffering coastlines against storm surges and tsunamis through  
wave attenuation (16). For socio-economic matters, mangroves  
provide benefits for coastal communities’ livelihoods. The  
socio-economic value of the mangrove is likely to be more than  
double of the direct forest product value through the ecosystem  
linkage with the aquatic production and the effect on fishery  
2
ni   
C    
N   
where C is index of dominance; ni is number of individuals of a  
species; and n is number of individuals of all species.  
Domination is a community characteristic that shows the  
abundance of species in a region (22), (23), (24), (25). The  
criteria of domination index according to are as follows: 0 <C  
<0.5 = There are no dominant species; 0.5> C> 1 = There are  
dominant species. To determine the diversity of Mollusca as an  
indicator of habitat, species index diversity (H) according to  
Shanon and Wiener (1949) in Magurran (26) was used with the  
equation:  
(17). A number of potentials inhabiting fauna such as fish,  
shrimp, and crabs are an important part of the mangrove  
ecosystem. Similarly, Mollusca groups (gastropod and Bivalvia)  
also play an important role in mangrove ecosystem and people's  
lives. Yet, scientific information related to Mollusca groups in  
Kaisu mangrove is not known for certain. Therefore, the aim of  
the research is to examine the diversity of molluscs (gastropod  
and Bivalvia) in Kaisu mangrove forest.  
ni  
ni  
N
H    
ln  
N   
where H is diversity index (Shanon-weinner index); ni is number  
of individuals of a species, N is number of individuals of all  
species. The evenness of species of Mollusca at the study site  
was analyzed using the index of evenness (e), according to  
Pielou (27), Odum (23), and Bratawinata (28) as follows:  
2
Material and Methods  
The study was carried out in Kaisu mangrove (study area)  
forest in the District of Bonggo in Sarmi Regency, Papua  
Province of Indonesia in a span of two months. The equipment  
used to conduct the study were Global Positioning System,  
levers, plastics, collection bottles, tweezers, digital camera,  
Vernier caliper, surgical boards, gauges, raffia and stationery.  
This study used observation methods to conduct the  
research. Purposive sampling was used for observation station.  
The characteristics and species of Kaisu mangrove forest are  
relatively similar with a forest width of approximately 150-350  
H'  
H'  
e   
LogS Hmax  
Hmax  2 lns  
where e is species evenness index; H is species diversity index;  
S is number of species. Evenness index according to Krebs(29)  
in Sinery (30) ranged from 0-1, where: 0.6-1 = high species  
evenness; 0.4 <e <0.6 = moderate species evenness; 004 = low  
species evenness.  
m. Considering the condition,  
2 sampling stations were  
determined in one transect 320 m long with site I position (75 m  
from land-sea point) dominated by Rhizophorasp, Avicenniasp,  
Bruguera gymnorhiza), and site II (position 250 m from point 0  
or 175 m from site I which was presented by species like  
Rhizophorasp, Bruguera gymnorhiza and Sonneratiasp). Each  
site had one observation plot with size of 20 m × 20 m. To  
determine the species and number of individuals, variables such  
as morphological characters of molluscs (gastropod and  
Bivalvia) in the form of color and body size (length, width,  
diameter expressed in cm) were observed. General condition of  
the study site was documented.  
3
Results  
3
.1 Species Composition  
Based on identification of the morphological characteristics,  
0 species of Mollusca were identified in Kaisu mangrove area,  
1
i.e., 7 families and 8 species of gastropod, 2 families and 2  
species of bivalves (Table 1 and Table 2).  
3
.2 Domination, Diversity and Evenness Index of Mollusca  
This research used the dominance, diversity and evenness  
The samples of Mollusca (gastropod and Bivalvia) were  
collected at low tide and on sunny day. The collected samples  
were preserved using alcohol 70% and put into specimen box.  
The samples were identified using the journal (18), (19), (20),  
index to analyze the level of species domination, variation of  
species and evenness of species, as indicators of community  
stabilization in Kaisu mangrove forest. The dominance, diversity  
and evenness index of Mollusca