Review of Environmental Features of the Java Sea (sadhotomo, B.) REVIEW OF ENVIRONMENTAL FEATURES OF THE JAVA SEA Bambang Sadhotomo') ABSTRACT Old information and recent data were synthesized in order to reveal comprenhensrve descriDtion of the environment feature of the Java sea. Descriptive analysis was performed on various foimat of data Physical feature of the Java Sea related to the eastern Indonesian waters and the northern reoion and impacts on the materials input and circulation in the coastal area. Two possible sourcei of variability's affecting lhe characteristics of the Java sea, the first was monsoonal variability and the second was the inter annual ones. Circulation pattern generates a specific stratiflcation of witer masi th-at would be very important for the repartition of the palagic fish concentration ano signiRcanl 6ct,orin affecting migratory scheme of the oceanic pelagic fishes, as we as stratificati;n or ptanitonil abundance and diversity KEYWORDS: environment, monsoon, migratory, Java Sea INTRODUCTION MATERIALS AND METHODS The Java is Sea located in the southern most of The data and information used in this studv are southeast Asia and bordered by three islands. from several source and studies document;d in Java in the south. Kahmantan (Boineo) in the north various format of flgure and textual information, as and Sumatera in the west. lt is also connected to well as from observations made durino acoustic the southern South China Sea by an ouflet. ie. cruise of RA/ Bawal Putih conducted by pelfish Karimata Strait, and widely ope'ned to eastern Project in the years 1992 to 19951 and recent region through Flores Sea. Thjs condjtion reveals a inhouse project in the year 2004 to 2005, (Figure possibility highly of influence by other ecological 1). Descriptive presentations are performed in area, at least, the northern and eastern areas. figures, charts, graphics and tables. Refigurizing Also, it is well known that the climate over the Java descriptively the text formats are needed governed rn ordel Sea-is by monsoonal variability (Berlage, to clarify and to synthesize the information. 1953; Wyrtki, 1956a; Durand & petjt, j 905). Many factors involved in the system of the Java RESULTS AND DTSGUSSION Sea may be deducted, but issues on the complexity of the interrelationship between many Morphological Feature of the Java Sea aspects, at least, need a wide range of diclplines and specific works which are bevond the scooe of Toponomy and bathymetry this study. Thus, in the context of this studv. a general knowledge on the functioning of The Java.Sea is part of the Sunda Shelf which ecosystem ts necessary in understanding the extends from the Peninsula of Indochina and ends pnenomena related to the bioecological aspects, in the continental slope near the l\radura lsland. lt population /.e. change, spatial Oistribution pittern, is some shallow waters with average of 50 m deep response of fishermen to disponibility of fish, as and bordered by three main islands, Sumatera in well as biological and population cnaracrers. the west, Java in the south and Kalimantan ln the north. There are three possible connections Thjs to study is aimed to briefly synthesize and other ecological areas the Southern China Sea compile existing the results of hydrographical waterg, Sulu, and Sulawesi Sea in the north and surveys made during 1900 to 1970 decades and the eastern Indonesian archipelago waters in the recent observations. This study consjsts of two east. In the north west and the northeast it is parts: the physical and biological enviroments. connected with some parts Karimata Strait and Makassar have been reviewed exhaustively Strait respectively and in the east it direcfly opens elsewhere (Potier & Boely, 1990; Durand & petii, to Flores Sea. 1995). lt includes an evaluation on climatic variability and its relafion to the hydrographical properties Inside the Java Sea five groups of islands and orographical feature of the spread in this area. group of Bangki and Betitung terrestrial area. In the northwest, Seribu lsland off Jakarta. Research lnstitute for Manne Fisheries, Muara BaruaJakarla 129 Ind.Fish Res.J. Vd.12 No.2 Desember-2006: 129-157 o tt J Longitude o at I Longituds { at 5 5 Figure 1. Selected tract used for analYsis' factor defining structure of bottom part, Bawean-Matasiri reoarded as a Karimunjawa in the middle. ::,i:i;Jt-e'iirorst lation of sedimentation in ine e'ast-nortneast and Kangean in southeast' -"u"p"n'oed drifted by rrvers grouP- or ii-it'" """ut'material considering the connecting areas' coastline d,.the Bv sea. i"uor"tting into this area along illt,i*'lJinJ-in the Southern south china rne part or the boftom southern Part of ;;;;i;"s iitanos. l9:t ;;"i;;-bt; lsland in sediment of this area is constituted taken into account' rro.ti"l" il,iaxassar Strait should be ir-"irit-niCn"10 olils formed bv highlv d"lt:,lt* r"u"i.'r" it'" nort[western part' the sea bed rs Sedimentatlon and orography iiiil"a'*iii i."J titeri"t to"o with coral (F'sJre small istands the bottom profile geological nature.of i-t in in" near some The terrestrial and "r"" a mixture or coral' sravel and the island surrounding the Java Sea could oe ;il#i,aie;;.i"i;f 130 Review of Environmental Features of the Java Sea (Sadhotono. B.) a. ir6 1!.i Source ot datar Losse & Dwiponggo 1977t lB) anet Emety et at. 1972\ Figure 2. Bottom subslrat of the Jeva Sea ((A), shell, debris while parts in some of non muddy be seen ln Figure 2, that sand or sandv substrate suDstrate are frequenfly covered by some specie; tend to be exist closer to the coast kalimantan or c^orat, giant poferlon of sponge. (Saeger el a/., while in the north coast Java, 1976). of fine silt content of sediment ate usually found. More detail observations made in the Java side area indicated . Rough examrnation on type of bottom substrate that highly silt content (more than 7S%) was found by observing soil attached in otterboard durino an at stations located in the north coast of Java (Wlde extensive crurse of RA/ Mutiara 4 (Saeger eial., et a/., 1989). lt is we known that the soit tvDe in 1976: Losse & Dwiponggo. 1977; Dwiionggo & Java is composed by gromosol and latosol tsadruddin. in the 1980) provides an additional high altitude and aluvial soil in the plane area in Inrormatton to the result of previous investigations northern part, whilst in Kalimantan mosfly by silica or Emery et at. (1972). Type of deposited material soil covered with peat on the top layer. rn the s,ea bed indicates a possible similarity with the soit at the river basin areas. The iluvial In the coastal areas surrounding sedrment input from . the Java Sea, the land relates to the nature the phenomena of sedimentation of geological characteristics ind highly input of the superficiai oi of material from the land are apparent. forhation catchment region (Bird, 1979). Or flver delta and natural formation of new coast line would be parallel phenomena wtth the The fluvial sediment input from land . the relates deposition sediment in the sea bed. In certain to the_ nature of geologrcal characteristics of the delta, sedimentation process is considerably high supentctat ot catchment region (Bird, 1979). lt can as shown by their morphological structure, such is 131 tnd.F,sh Res.J Vol.l2 No.2 Desember-2006: 129-157 multi delta and single frnger types of Mahakam and enriched area. lt should be noticed that the Solo deltia, respectively. These types of delta are coverage of the local current would extend to usually constructed by a predominance influence southeinmost of Makassar Strait. Horizontal of rivei rather than other factors (Allen efal., 1979). movement of the buoyant material could be said to of nutrient "ariation of the amount of suspended sediment be more dominant than vertical transport and other material input from land link to river debt from the deeper part beyond the slope and erosion level. However, distribution pattern of Unfortunately, .no large scale measurement had precipitation rate, topography (slope of gradient) been made for allowing to figurise the distribution ind vegetation coverage take an important.role of sedimentation level over whole Java Sea determining this variation. In this case' high erosion orocess and fluvial sediment yield in Java Climatic Factol can also be considered as the other example. Monsoon wind For these reasons, the influence of Solo River an extensive areas on the variability of coastal area in the north coast The monsoon influences part of Japan The The catchment area of this river from east of Africa to southern - of Java is obvious. ot tne is relatively large and occupied by dense Java Sea, as part of its coverage areas (average) volume is influenQe, its climatic system is completely population.' Also- its which enermous compared with other big qoverned by the monsoonal climate toirsiderablv hydrographic condition in Java and Sumatera (Table 1) as well as a Seasonally ;ffects its rivers (1987); the monsoon coulo oe limited veaetation coverage (forested zone) Followino-as Fieux semi annual reversal of wind and Undoubtly, i consequence of short period of fresh defined a in the coastal current regime. The areas influenced by the- water input and high sedimentaton -could term of gener,ted by this condition Hoekstra monsoon be expressed in area wili be (Pedalabord' amount of sediment atmospheric and oceanic parameters et a/. (1988iestimated that reglme oI dry season (southeast 1970). Bv this definition. the monsoon ro"o trit 56lo River during could be only 10% of total annual *inJ'and'cunent over the Java Sea area tons*nl account for where the million ton.