Diversity of Gastropod and Bivalve Molluscs in Kaisu Mangrove Forest of Sarmi Regency, Papua Province, Indonesia

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

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

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).

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



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.





















H  





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:

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

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; 0–04 = 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.

Results

.1 Species Composition

Based on identification of the morphological characteristics,

0 species of Mollusca were identified in Kaisu mangrove area,

i.e., 7 families and 8 species of gastropod, 2 families and 2

species of bivalves (Table 1 and Table 2).

.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