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MANGROVE ECOSYSTEM






Ecosytem Mangrove in Aceh Besar and Banda Aceh Before and After Tsunami


Leti Febriyanti
26010113120006



Department of Aquatic Resource Managemenet
Faculty of Fisheries and Marine Science
Diponegoro University
Semarang
2013/2014
Ecosytem Mangrove in Aceh besar and Banda Aceh Before and After Tsunami
Leti Febriyanti
26010113120006

Abstract
 The objective of the present study was to determine the condition of mangrove ecosystem on comunity structure of mangrove vegetation.  Mangrove enstablisment requires protection fram strong winds and wind generated waves, as wave action prevents seedling establisment.  In the mangrove ecosystem there are many species Grastopods and Bivalves. There were 14 species or Grastopoda and 5 species Biveles belongging to seven and four families, respectively in Banda Aceh and Aceh Besar districts, Indonesia. The higher abundance of Gastropods was optained in study site 4 (169ind/m2) wich was dominated by Potamididae (151 ind/m2).  These species richness and abundance of Grastopods and Bivalves has decreased in post tsunami. Species richness of Gastropds was higher compared to that of Bivalves and the values decreased after tsunami, however their species compotitions were similar between pre and post tsunami.
Key Words: mangrove, comunity structure, Gastropods, Bivalves
Introduction
Mangrove are a diverse of unrelated tress, palms, shrub, vines and fems that share ability to live in waterlogged saline solis subjected to regular flooding. Mangroves are specialised plants that have developed unusual adaptation. Mangrove grow in saline costal sediment habitats in the tropic and subtropic area. Many mangrove forest can be recognized by their tangle of prop roots that make the tress appear to be standing on stilts above the water. In the mangrove ecosystem there are many species grastopods and Bivalves.
The Gastropoda or gastropods, more commonly known as snails and slugs, are a large taxonomic class within the phylum Mollusca. The class Gastropoda includes snails and slugs of all kinds and all sizes from microscopic to large. Grastopos are one of the most diverse group of animal, both in from, habit, and habitat.
Bivalvia is a class of marine and freshwater molluscs with laterally compressed bodies enclosed by a shell in two hinged parts. Bivalves include clams, oysters, mussels, scallops, and numerous other families of shells. The majority are filter feeders and have no head or radula. Most bivalves bury themselves in sediment on the seabed, where they are safe from predation.
Material and Methods
The study was conducted in the area of mangrove rehabilitation in Banda Aceh and Aceh Besar districts, Indonesia. The study was conducted for six month from May to November 2011. The mangrove vegetation in the study areas are the newly formed vegetation post mangrove rehabilitation programs. Five sampling site (10m x 10m) were selection by satified random samplin method with dividing the study area into several or strata based or characteristics of the different planting age. Acording to field asssement, there were five leves of mangrove vegetation age found at study area i.e. from 1 year old to 5 year old. Every site was presentetive of mangrove age level where site one was reprative of one year old and situated in Deah Glumang village (05o33’42,3’’ N, 95o17’35.7’’E), site two was representative of two year old and situated in Lampageu village  (05o33’08,2’’ N, 95o14’13.9’’E), site three representative of three year old and located Deah Glumpang village (05o33’34.3’’ N, 95o17’20.0’’E), site four that representative of four year old and located in Lamnga village  (05o37’01.6’’ N, 95o23’46.6’’E), and site five was representative of five year olg and occurred in Lamnga village (05o36’35.8’’ N, 95o19’25.6’’E).
Biological observation includes the retrieval of mangrove data and molluks (Gastropods and Bivalves). Samples were collected using the square transects of 1 x 1 (m) into 10 x 10 (m) as a plot determind randomly in very sampling side and every plothad three square transect Mollusk sample were collected in two ways: by collecting for epifauna and taking the substrate to a depth of 15 cm for infauna. Mollusk sample were sorted and prserved in bottle sample containing 70% alcohol. Each bottle sample was labeled with side, date and other important information.
Result and Discussion
There were 14 species or Grastopoda and 5 species Biveles belongging to seven and four families, respectively. These results were lower compared to Macitosh et al (2002) who recer oded 33 species of mollusk in mangrove rehabilitation area in Thailand. Gastropoda and Bivalves obtained during to observation  generally live on the surface on the substrate, attached to the roots, stem and leaves of mangrove trees.
We found that total abundance of Gastropods and Bivalves was viduals with average density of 6 ind/m2 and 28 invidual with average density of 6 ind/m2.
Family/Species
Study Site
Total
1
2
3
4
5
Cantharus fumosus
0
0
0
1
0
1
Cerithiidae






Cerithium patulum
7
12
9
0
0
28
Clypeomorus granosum
5
5
5
5
2
22
Clypeomorus moniliferum
0
0
4
0
0
4
Conidae






Phasmaconus radiatus
1
0
1
0
0
2
Littorina Scabra






Littorina Scabra
6
4
3
3
2
18
Littorina undulata
0
1
1
0
0
2
Nassariidae






Nassariidae olivaceus
1
1
0
1
0
3
Nassarius distortus
1
2
7
4
0
14
Neritidae






Nerita undata
1
1
1
0
0
3
Neritaplanospira
2
1
1
1
0
5
Nerita sp
1
0
0
3
0
4
Ptamididae






Cerithidae cingulata
0
0
39
150
74
263
Terebralia palutris
0
0
0
1
0
1
Total Individual
25
27
71
169
79
371
Number of species
9
8
10
8
3
14

The higher abundance of Gastropods was optained in study site 4 (169ind/m2) wich was dominated by Potamididae (151 ind/m2). These resulth are in agreement with Dharma (1988) explained that Potamididae had a wide geograpical distribution and also found in high abundance of Bivalves was found in study 3 with density of 14 ind/m2 dominated by Isognomonidae (8ind/m2). Overall, Obtreidae had high abundance in present study (13 ind/m2).
Family/Species
Sty Site
Total
1
2
3
4
5
Isognomonidae






Pedalion isogmomum
1
2
8
0
0
11
Lucinidae






Lucina sp.
1
1
0
0
0
2
Ostreidae






Crassotrea cucullata
0
1
3
0
0
4
Saccostrea echinata
0
0
2
5
2
9
Veneridae






Gafrarium dispar
0
1
1
0
0
2
Total
2
5
14
5
2
28
Number of Species
2
4
4
1
1
5

In general, the abundance of Grastopods has increased with vegetation age increasing, for example study site 4, the vegetation of four year old had the hihgest the side 4 had higher C-organic content (0.9%) compared that site, therefore we assumed that the higher abundance of Grastopods at sie 4 problably due to higher in C-organic content. Contribution of organic matter was influenced by the litter falling in the sorrounding vegetation area and would be primarily contribution in substrate. In addition, we also recorded that the precentage of silt and sand were higher at side 4, i.e. 15% and 83% respectively, but with lower percentage of clay (2%). Acording to Rangan (1996) the substrate condition influences the development of biotic comunities, where muddy with a little clay is a desirable substrate fo Gastropods,
The value of C-organic content in the substrate was 0.8%, 0.8%, 0.7%, 0.9% and 0.6% fo site 1,2,3, 4, and 5, respective. The C-organic content recorded in the present study (post stunami) was lower than previous study (pre stunami). This condition exists problably because stunami brought out the sand from other site into mangrove area. Sukardjo (1994) found that quantities of C-organic matter in Tanah Grogot, East Kalimantan was from high density of trees because tha fallen litter of mangrove leaves contributes signifivantly to the higher organic matter in the soil. Futhermore, there was a cotent in the substrate with carbon in the substrate ans also axygen dissolved.
The sediment examination showed that the presentage of sand, silt, and cly fractions have ranged from 82.5 to 91.0%, 5.0 to 15.0% and 2.0 to 5.0%, repectively. Preentage of sand was high probably because sampling location directly receive material brouhgt fro the sea by the current despite in mangrove are during tsunami in late December 2004.
We found that the age of vegetation did not effect the abundance of Bivalves. However, the higher abundance of Bivalves was found at study site 3 with 3 year old of mangrove. This is probably due to the higher density of mangroe (3 ind/m2) at this site, as it had a lot of root brancing used for Bivalves living on. Mangrove roots represent the area of hard subtrate colonized by massive sponge, oyster (ostireidae), and barnalcle (Channicci at al 2008). Mareover; Guerreiro et al (1996) ex-pressed that sediment textures, tidal elevetion and forest type effect the distribution of macrofauna in mangrove ecosystem. Cherithidea cingulata was the dominant species in the study area. We assumed that this species had a good adaptation on evironmental condition at these sites and therefore it won the competition for food and habitat. In addition, we found three species of native mollusks in mangrove ocosystem i.e. C. cingulata. Terebralia palustris and Nerita planospira; Three facultative mollusks i.e. Litorina scabra, C. patulum, and Crassostrea cucullata and two migrant mollusk i.e. Nerita undata and Clypeomorus moniliferum.
            These species richness and abundance of Grastopods and Bivalves has decreased in post tsunami. For example, at the site 1, before tsunami, the species richness of Gastropod consisted in 11 species with desity of 52 ind/m2 and they decreased only 9 species with desity 25 ind/m2 after tsunami. Macintosh et al (2002) reported that Potamididae was one gastrops families was more representative of the younger plantation, assumed as they graze the younger mangrove leaves like Littorinidae and therefore.
Decreasing in species richness and abundance post tsunami probably due to changing in community structure post tsunami of mangrove, where the density of mangrove community in pre tsunami was high than in post tsunami, The tsunami catatrophe destroyed mangrove vegetation and also distrupted community srtucture of biotic that lives in it. In general, the C-organic content bofore tsunami was also hgher that after tsunami at site 1; the C-organic content before tsunami 1.06% and it decreased to 0.8% after tsunami.
The diversity index (Shannon index) has verid from 0.51 to 2.95 at site 1, respectively, with average of 2.02 indicating a low value. The evenness index (E) has veried from 0.26 to 0.85 with an average of 0.58. These average value indicate that the comunity condition was uns table. However, the mollusk community at site 1 was relatively stable compared to other sites.
In addiction, the dominance index (D) has ranged between 0.19 at site 1 to 0.84 at site 5 with average of 0.46 indicating a moderated value. The dominance index showed the degree of predominace of one of few species in an ecological community. Ovreall, we found that the low diversity index, the unevenly distributed individual within species and the moderate evenness and dominance showed and unstable community structure at the study sites post tsunami.
Conclution
Species richness of Gastropds was higher compared to that of Bivalves and the values decreased after tsunami, however their species compotitions were similar between pre and post tsunami. Gastropods were dominate by Potamididae while Bivalves were dominated of gartropods and Bivalves in the study area was in lower category. The abundance of Gastropods increas with increasing vegetation age, but the age of vegetation did not affect the abundance of Bivalves, and community structure at the present study was unstable. 
References
Channicci, S., Damien, B., Sara, F., Thomas, J. S., Joachim, O., Farid, D. G., 2008. Fanal impact on vegetation structure and ecosystem function in mangrove forests: a review.Aquatic Botani 89:186-200.
Dharma, B., 1988. Indonesia Shells ( Siput dan Kerang Indonesia). 111 pp., Sarana Graha, Jakarta.
Irma Dwiyanti, Karina Sofyatuddin. 2012. Diversity of Gastropods and Bivalves in Manrove Ecosystem rehabilitation areas in aceh Besar and Banda Aceh districts, Indonesia. Aquaculture, Aquarium, Conservation & Legislation 5:55-59.
Macintosh, D. J., Ashton, E.C., Havanon, S., 2002. Mangrove rehabilitation and intertidal biodervisity: a study in the Ranong mangrove ecosystem Thailand. Estuarine, Coastal and self Science 55:331-334.
Rangan, J., 1996. Community structure and typology of Grastopods on mangrove forest zone, Kulu district, Minahasa, North Sulawes (Struktur dan Tipology Komunitas Grastopoda dapa Zona Hutan Mangrove Perairan Kulu, Kabupaten Minahasa, Sulawesi Utara). Program Pasca sarjana, IPB. Bogor, Indonesia.

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