Jurnal Iktiologi , 10(2):101-110

Spawning habitat of sarasinorum (Family: Telmatherinidae) in Lake Matano [Habitat pemijahan ikan (Famili: Telmatherinidae) di Danau Matano] Jusri Nilawati1,2,, Sulistiono3, Djadja S. Sjafei3, M.F. Rahardjo3, Ismudi Muchsin3 1 Graduate student of School of Graduate Studies, Bogor Agricultural University, Indonesia 2 Department of Fisheries, Faculty of Agriculture, University of Tadulako, Palu, Indonesia e-mail: [email protected] 3 Department of Aquatic Resources Management, Bogor Agricultural University, Indonesia

Diterima: 7 Juni 2010; Disetujui: 21 September 2010

Abstract A study on habitat of Telmatherina sarasinorum was conducted in Lake Matano. An underwater observation on the habitat was performed to allow description on habitat while investigating its reproductive behaviour. There were two types of spawning habitat on the fish observed. The first was shallow beach with flat contour and bottom covered by cobble and little sand in between which was located in littoral area with trees on the lake sides. The second was deeper water with steeper bottom which has hanging down roots and fallen down stems and twigs of any trees covered by alga. In the two habitats the fish prefers shading places provided by any trees existing on the lake sides as spawning sites. The fish was not observed spawn in places covered by dense cobbles and open waters exposed directly to sunlight. Such a habitat specialist becomes important factor needed to be taken into account in the attempts to conserve the fish and its habitat in Lake Matano. Maintaining the existence of spawning habitat through protecting the presence of terrestrial vegetation surrounding the lake is important key for conservation of the fish and its habitat.

Keywords: habitat preference, Lake Matano, spawning arena, spawning substrate, Telmatherina sarasinorum.

Abstrak Penelitian tentang habitat Telmatherina sarasinorum dilakukan di Danau Matano. Pengamatan bawah air pada habitat ikan ini dilakukan untuk membuat gambaran mengenai habitat sambil meneliti tingkah laku reproduksinya. Ada dua tipe habitat pemijahan ikan yang diamati. Pertama adalah pantai dangkal dengan kontur datar dan dasar ditutupi oleh kerikil dan sedikit pasir diantaranya yang terletak di daerah litoral dengan pohon-pohon di pinggiran danau. Kedua adalah perairan dalam dengan dasar lebih curam yang mempunyai akar-akar menggantung serta batang dan ranting pohon tumbang yang diselimuti oleh alga. Pada kedua tipe habitat tersebut ikan menyukai tempat-tempat teduh yang mendapat bayang-bayang dari pohon yang ada di pinggiran danau sebagai tempat pemijahan. Ikan diamati tidak memi- jah di tempat-tempat yang ditutupi oleh kerikil yang padat dan perairan terbuka yang terpapar langsung oleh cahaya matahari. Habitat khusus demikian merupakan faktor penting yang perlu dipertimbangkan dalam usaha konservasi ikan dan habitatnya di Danau Matano. Pemeliharaan habitat pemijahan melalui perlindungan keberadaan vegetasi terestrial di sekeliling danau adalah kunci penting untuk konservasi ikan dan habitatnya.

Kata penting: arena pemijahan, Danau Matano, pemilihan habitat, substrat pemijahan, Telmatherina sarasinorum.

Introduction depth, high water transparency (the Secchi disc Island has long been known as still can be visualized from the distance of 23 m), the hotspot in global biodiversity because of high steep sides along the lake with relatively narrow endemism among its native faunas (Whitten et littoral area, and it is famous as an oligotrophic al., 2002), 76% of native in Sulawesi are lake. The lake is at least inhabited by seven Tel- the endemics (Kottelat et al., 1993) and unique. matherinidae species (T. abendanoni, T. antoni- Lake Matano is one of the world ancient lakes ae, T. obscura, T. opudi, T. prognatha, T. sara- which are situated in the central south of Sulawe- sinorum, and T. wahjui) (Kottelat, 1991) and 1 si Island, and it is in the uppermost end of Malili newly described species T. albolabiosus (Tantu Lakes System. Lake Matano (Haffner et al., & Nilawati, 2008), and one other species – Tel- 2001) has a total area of 164 km2, 590 m in matherina bonti – (Tantu & Nilawati, 2007) re-

Masyarakat Iktiologi Indonesia Nilawati et al. ported previously by Kottelat (1990) only found fish in Lake Matano. Observation on these as- in . Telmatherinidae is known for pects was conducted simultaneously with obser- male polychromatism. vation on reproductive behaviour in both habitat Many studies were previously conducted types (reproductive behaviour aspects in prepa- on the fishes of Telmatherinidae from Lakes Ma- ration). The aim of the present study was to de- lili including aspects of diversity and evolution, termine habitat selection for oviposition site of adaptive radiation and population genetics, main- the fish by identifying its preferred physical cha- tenance of male colour polymorphism, and com- racteristics of spawning substrate in the field that paring mating behaviour (Herder et al., 2006; determine factors supporting the existence of the Heath et al., 2006; Gray et al., 2006; Gray & fish reproductive strategy. The study of fish rep- McKinnon, 2006; Nilawati & Tantu, 2007; Tantu roductive habitat is expected to help attempts of & Nilawati, 2007; Tantu & Nilawati, 2008). conservation of the endemic fish and its habitat Among the above studies, however, there was no in Lake Matano. study specifically focused on spawning habitat. T. sarasinorum is known as a small endemic fish Materials and methods from Lake Matano being one of predominant Research was conducted in Lake Matano species among the telmatherinids. The fish inha- District of East Luwu, South Sulawesi (02° bits littoral area and has two differential spawn- 25.00′ -02°34.00′ S and 121°12.00′ -121°29.00′ ing habitat types (phytophil and lithophil). The E). Field activities were performed in September fish has a relatively limited distribution along the 2008; December 2008; March 2009; and June shallow lake sides and often found in southern 2009. Spawning locations were established based lake side (Kottelat, 1991). In many fish species, on underwater observations through snorkelling. spawning incorporates behavioural factors that These locations were considered from the pre- ensure to appropriate conditions for the eggs and sence of mating events characterized by pairing offspring after hatching. A common behavioural fish and they performed quivering. Females pre- factor is the selection of an appropriate location sented movements as laying eggs and males pre- through preference of particular spawning struc- sented movements as releasing sperm. Observati- tures. The appropriateness of the selected locati- ons were accomplished in 12 localities (Figure 1) on for egg and larval development affects morta- and these underwater observations were conduct- lity of the offspring, especially in species without ed for three hour in each location. In each samp- parental care. ling locality observer performed slow swimming The appropriateness of a location, which by snorkelling along 50 meter transect in the ensures protection on the eggs and larval deve- depth between 0.5 and 2 meter parallel to the lopment and survival of the offsprings, becomes shoreline. The observer identified particular lo- a major control in species with no parental care. calities of spawning arena of the fish. The The fish is one of fish species inhabits an oligo- spawning arena here is defined as a restricted trophic lake known as substrate spawner and area, almost looks like a stage, in which spawn- does not perform parental care. ing activities were performed by the presence of The present paper reports on physical as- male displays, pairings and courting of males and pects of spawning habitat characteristics of the females of the fish. The spawning arenas were

102 Jurnal Iktiologi Indonesia Spawning habitat of Telmatherina sarasinorum then marked by the observer and percent of ma- The first was spawning arena on bottom substra- terial coverage that compose spawning substrates te, in which the arena composed of cobbles with was subsequently analyzed according to Wolman sand traps in between. The second was spawning method (1954) (Table 1). The number of spawn- arena composed of hanging down roots and/or ing arena within transect line was also recorded. fallen down stems and twigs covered by alga and freshwater sponge. Table 1. Classification of substrate sizes Spawning arena was generally located Material Size range (mm) Silt/clay 0-0.06 near the shoreline, within water depth of 0.30- Fine sand 0.061-0.25 Medium sand 0.26-0.5 0.75 meter, with water transparency of 10-15 me- Coarse sand (pea gravel) 0.51-2 ter (distance of the observer vision relative to- Gravel 2-64 Cobble (rubble) 65- 256 wards a white plate with the dimension of 30 cm Boulder 257-4096 Bedrock >4096 x 30 cm horizontal in water column). The spawn- Source: Wolman (1954) ing arena on bottom substrate is located in littoral with relatively flat bottom contour. Whereas Results spawning arena with hanging down roots and/or Underwater observations showed that fallen down stems/twigs is located in deeper wa- spawning habitat of the fish has the form of an ter with relatively steep bottom contour (Figure arena in which the fish presented in the arena 2). These two types of arena were always observ- performed male-male displays, pairings and ma- ed be under shading and or near shading from ve- ting. There were two types of spawning arena. getation and cobbles/boulders.

2⁰ 25’00” S

N

121⁰ 12’00”E 121⁰ 29’00 121⁰ E ”

2⁰ 34’00” S

Figure 1. Sampling localities in Lake Matano Note: 1-12 were the site numbers indicated in Table 2

Volume 10 Nomor 2 Desember 2010 103 Nilawati et al.

The fish presented within spawning arena blages of the fish performing mating activity. were sexually mature individuals. They perform- Whereas on silt substrate mating activity of the ed their fitness in the form of male colour dis- fish was never found. The spawning arena ob- plays by unfurling brighter, stronger and colour- served has particular physical characteristics ful larger fins, following by pairing, fighting for (Table 2). females, and movement such as releasing eggs Spatially, the highest number of spawning and sperm. Within bottom spawning arena the arena in transect was found in Island I and Island movements of reproductive behaviour were per- II with four spawning arenas (each with two formed horizontally towards the bottom, while in roots habitat and two bottom habitat). In Kupu- other type of spawning arena reproductive beha- kupu Beach, Salonsa Beach, and Old Camp each viour were performed both in vertical and hori- had three spawning arenas. Where Kupu-kupu zontal movements. Beach and Old Camp only had one habitat type, Males and females presented in spawning in Salonsa Beach we found two habitat types arena were not only pairing males and females (two bottom habitats and one root habitat). In but also single males and single females. The Matano Village, Salure River, and Tanah Merah pairing fish in spawning arena were observed al- River there was only one spawning arena each. ways be followed by other males disrupted the There was no spawning arena in localities sur- spawning events and seemed likely ready at any rounding Petea River and Sokoio although un- time for eating the freshly laid eggs on the sub- derwater survey found several the fish indivi- strates. duals swimming around the transects (unpublish- Pairing males and females were observed ed data). actively spawned onto the substrates under shad- Several spawning arenas during dry sea- ing condition, which provided by the tree shaded son dried as decreasing water level and they were the arena from the lake sides or large cobble or inundated during rainy season as water level in- small boulder shaded the arena (description of re- creased. However, currently, condition of Lake productive behaviour is in preparation). When Matano has changed. Period of dryness and inun- the water was waving and bottom substrates were dation changed from the original mode and not mixed there was no mating activity observed, following the period of dry and rainy seasons. and the fish were observed moved to deeper and This seemed likely due to dam operation in the clearer water. purpose of maintaining water level in Lake Mata- The present study also found that spawn- no. Dam operation caused those spawning arenas ing activity rarely occurred on bottom substrate experiencing longer inundation period (Figure 3). within open water without shading effect from terrestrial vegetations or large cobble and/or Discussion small boulder. Within a such open area the fish Sexually mature individuals of the fish used most of their time for feeding by following seemed to have spawning habitat preferences. the pairing congeneric, T. antoniae and foraging They seemed identify spawning substrate type’s the freshly laying eggs. The study also noted that potential for spawning arena. In relatively flat on the bottom substrate covered by cobbles and/ bottom of the beach individuals preferred bottom or sand substrate it was rarely found the assem- substrate composed of cobbles with sand traps in

104 Jurnal Iktiologi Indonesia Spawning habitat of Telmatherina sarasinorum

Figure 2. Picture of spawning arena on bottom substrate and roots A. Hanging down roots and/or fallen down stems/twigs; B. Sand and cobble substrate between or structures looked like sand pools Reasons of protecting the offsprings were also among the cobbles. Mating events, characterized show-ed in other species. Walleye preferred for by movements as if egg release by females and gravel and cobble substrates with low flows in sperm release by males, performed onto the sand Upper Wabash River, Indiana (Weitzel & Pyron, surface. The fish is known as non parental care 2005). The walleye tended to use habitat with in species. Females observed lay their eggs onto the stream cover during low discharge conditions sand in order to protect them from the dynamics and to move up onto flooded banks with timber of water movements that possibly drift the eggs during high flow periods. Riparian vegetation or indeed caused egg mortality. In addition, the seems to be beneficial for the species during eggs laid onto the sand would oxygenationed flood events. Spine loach showed a strong prefer- which is needed for development. During our ob- ence on dense vegetation as spawning substrate, servations there was no pairing the fish found suggesting this factor to have great importance in spawned in silt substrate. Beside possible reasons reproductive biology (Bohlen, 2003). of vision, this might be one of the ways for the Beach habitat with relatively flat bottom fish to ensure the survival of their offsprings. covered by sand cobbles and habitat with hang-

Volume 10 Nomor 2 Desember 2010 105 Nilawati et al. ing down roots and/or fallen down stems/twigs that the fish performed oviposition selection covered by alga and/or freshwater sponge were among dense vegetation. The existence of vege- preferred as spawning arena. Oviposition was ac- tation along the lake edges, which has submerge ted upon roots or stems covered by alga/freshwa- rooting system and terrestrial vegetation which ter sponge. In this spawning arena type it seemed shaded the water surface from direct sunlight likely that females hided the freshly laying eggs might play an important key towards the exist- among algal or sponge, in purpose to protect ence of spawning arena (personal observation). them from predator. In addition, alga/sponge also To the best of our knowledge, this is the first re- provided the offsprings by the food availability veal on the role of shading effect in endemic fish after hatching. Such this way, although the fish spawning under natural conditions. This, how- did not perform parental care for the offsprings ever, need to test through advanced study. The but such oviposition selection is the way of the shading might has correlations with survival of fish to ensure survival of the offsprings. Behavi- the eggs and the offsprings. The shading in the our of oviposition on the sand and among alga/ arena also might help in protecting the eggs from sponge was intended to protect the offsprings vision of predator. from filial cannibalism often exhibited by cons- There is also possibility that conditions in pecific males. Filial cannibalism by the males the arena with shading effect are preferred by the was described by Gray et al. (2006; 2007; 2008). fish for spawning because of correlation with en- The present results coincide with the re- vironment light condition. The role of environ- sults of the other studies on different systems. mental light has been described by among them For example, Bohlen (2003) studied spawning Maan (2006) and Gray et al. (2008). Substrate habitat of spined loach (Cobitis taenia), found colours will determine the background colour

Rainfall (mm) Water level (m dpl)

Figure 3. Water level and rainfall in Lake Matano

106 Jurnal Iktiologi Indonesia Spawning habitat of Telmatherina sarasinorum

Volume 10 Nomor 2 Desember 2010 107 Nilawati et al. against which an object is observed. Therefore, the relationships between fish composition and for example, a blue fish will look very conspi- their habitat in the river including substrates. cuous when viewed against a yellowish back- There were closed relationships between charac- ground. However, the ambient light spectrum, teristics of substrate, water depth and composi- namely the light that will illuminate the fish and tion of fishes in large river ecosystem (Mueller & the substrates and everything under water, is de- Pyron, 2010) who studied fish assemblages and termined by the water itself and the particles dis- substrates in Middle Wabash River, USA. solved and suspended in it (Maan, personal com- Depths and substrate composition determined munication). This was in agreement with field fish assemblage composition in Wabash River. observation, and with results of Gray et al. They found that the upstream sites which had (2008). Blue males the fish in spawning arena shallow depth and coarse substrates (cobbles and with sand cobble substrate were predominant gravel) had several fish species that are classified over the other colour males. While in vegetated as intolerant. While the downstream sites which arena with hanging down roots and fallen down had habitats with increased turbidity and silt sub- stems/twigs covered by alga and/or freshwater strates, were dominated by tolerant, large-bodied sponge, yellow males were dominant. In male generalist species. The downstream sites are cha- orange throat darters (Etheostoma spectabile), racterized by greater depth and increased frequ- under natural conditions, size and nuptial colora- encies of fine substrates (i.e., sand and silt). In tion do not have correlation with spawning suc- addition, when the hydrologic regime of the Wa- cess (Pyron, 1995). Females in this species also bash River is altered, it seemed likely that sub- showed no preferences for bright versus dull ma- strates will also degraded. Variation in substrates les. Males and females did not differ significant- appears to directly control the distribution and ly in size. abundance of many Wabash River fishes. Maintaining diversity of habitat in Lake Rainfall surrounding Lake Matano pre- Matano is important for conservation of endemic sently does not influence the dynamics of water fishes. The fish spawns in sand cobble habitat level. This condition might evolutionarily change and vegetated area with hanging down roots and reproductive periods of the endemic fishes in La- fallen down stems/twigs covered by alga and/or ke Matano. This differs from the previous natural freshwater sponge, particularly localities with conditions (unpublished data) in which water shading effect from terrestrial vegetations along level are correlated with temporal rainfall sea- the lake sides. Therefore, it is important to main- sonally. During rain season water level increases tain the existence of shading by conserving ter- and during dry season water level drops natural- restrial vegetation along the sides of Lake Mata- ly. no. The fish preferred oviposition sites on sand pools among cobbles so that the presence of ha- Conclusion and suggestion bitat with such substrate need to be defended. Telmatherina sarasinorum has preference Landscape changes along sides of the lake might on spawning habitat of an arena in sand cobble remove vegetations and sand cobble areas which habitat and in vegetated habitat which have shad- cause habitat loss for the fish spawn in such spe- ing effect from the trees existed on the lake sides. cific sites. Many studies have been conducted on Maintaining the existence of spawning habitat

108 Jurnal Iktiologi Indonesia Spawning habitat of Telmatherina sarasinorum through protecting the presence of terrestrial ve- School of Graduate Studies, Bogor Agricultural getation surrounding the lake is important key for University. conservation of the fish and its habitat. In spite of known as non parental care, however, selection References on sand traps among the cobbles and alga/fresh- Bohlen J. 2003. Spawning habitat in the spined loach, Cobitis taenia (Cypriniformes: Cobi- water sponge covered hanging down roots and/or tidae). Ichthyological Research, 50:98-101. fallen down stems/twigs as oviposition site is a Gray SM, Dill LM, McKinnon JS. 2007. Natural reproductive strategy of the fish to ensure the history miscellany: cuckoldry incites can- nibalism: male fish turn to cannibalism survival of its descendant. when perceived certainty of paternity de- Considering the role played by the terres- creases. The American Naturalist, 169(2): 258-263. trial vegetation along the lake sides and sand Gray SM, McKinnon JS, Tantu FY, Dill LM. traps among the cobbles it is suggested to main- 2008. Sneaky egg-eating in Telmatherina tain the landscape of terrestrial area surrounding sarasinorum, an endemic fish from Sulawe- si. Journal of Fish Biology, 73:728-731. the lake and to prevent unrestrained tree cuttings. Land clearing in the forest surrounding the lake Gray SM, Dill LM, Tantu FY, McKinnon JS. 2006. The maintenance of male colour may increase siltation into the lake that eventual- polymorphism in the Telmatherinids of the Malili Lakes: implication for conservation. ly may cover sand pools in which the fish per- In: Hehanusa PE, Haryani GS, Ridwansyah formed reproductive activity. In addition, it is I (eds.). Proceedings International Sympo- also suggested to protect bottom structure of sand sium: the ecology and limnology of the Ma- lili Lakes. Bogor, Indonesia 20-22 March cobble in littoral area which is preferred by the 2006. LIPI-PT INCO Tbk. pp. 55-60. fish for oviposition site. Consideration is needed Gray SM & McKinnon JS. 2006. A comparative to be taken into account in dam operation by fol- description of mating behaviour in the en- demic telmatherinid fishes of Sulawesi’s lowing the period of dry and rainy seasons to Malili Lakes. Environmental Biology of maintain natural water level dynamic condition. Fishes, 75:471-482. Haffner GD, Hehanussa PE, Hartoto DI. 2001. The biology and physical processes of large Acknowledgement lakes of Indonesia: Lakes Matano and To- We are indebted to Fadly Y. Tantu for the wuti. The Great Lakes of the World (GLOW): Foodweb, health, and integrity. field work. We thank Moh. Syahril Abdulwali, pp. 183-192. Syukri Abdulwali, and Sinyo Rio for field assist- Heath D, Haffner D, Roy D, Walter R. 2006. ance. We do thank Syahrir and Anda for profes- Adaptive radiation and population genetics of the Telmatherinidae in Lake Matano. In: sional boat. We acknowledge Ir. Noel Layuk Hehanusa PE, Haryani GS, Ridwansyah I Allo, MM of the BKSDA Sulawesi Selatan I for (eds.). Proceedings International Symposi- um: the ecology and limnology of the Malili granting research permission. The funding for Lakes. Bogor, Indonesia 20-22 March 2006. this study was made possible by PhD Research LIPI-PT INCO Tbk. pp. 61-66. Grant No. 019/13.24.4/SPK/BG-DP/2009. Thank Herder F, Hadiaty RK, Schliewen UK. 2006. Di- versity and evolution of Thelmatherinidae also goes to Peter Sampetoding, Andi Erwin Sya- in the Malili Lakes system in Sulawesi. In: rief, Kaimuddin, and Megawati Ihyamuis from Hehanusa PE, Haryani GS, Ridwansyah I (eds.).Proceedings International Symposi- PT INCO for providing part of logistical support. um: the ecology and limnology of the Malili This research was presented as partial fulfilment Lakes. Bogor, Indonesia 20-22 March 2006. LIPI-PT INCO Tbk. pp. 67-72. of the requirements for the PhD degree in the

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Kottelat M. 1990. Sailfin silversides (Pisces: Tel- ikanan dan Kelautan Universitas Gadjah matherinidae) of Lakes Towuti, Mahalona Mada. BI-5:1-6. and Wawantoa (Sulawesi, Indonesia) with Pyron M. 1995. Mating patterns and a test for descriptions of two new genera and two female mate choice in Etheostoma spec- new species. Ichthyol. Explor. Freshwaters, tabile (Pisces, Percidae). Behaviour Eco- 1(3):227-246. logy and Sociobiology, 36:407-412. Kottelat M. 1991. Sailfin silversides (Pisces: Tel- Tantu FY & Nilawati J. 2007. Keanekaragaman matherinidae) of Lake Matano, Sulawesi, ikan dan kondisi habitatnya di Danau Mata- Indonesia, with descriptions of six new spe- no Sulawesi Selatan. In: Isnansetyo A (ed.). cies. Ichthyol. Explor. Freshwaters, 1(4): Prosiding Seminar Nasional Tahunan IV 321-344. Hasil Penelitian Perikanan dan Kelautan Kottelat M, Whitten AJ, Kartikasari SN, Wirjoat- Tahun 2007. Yogyakarta, 28 Juli 2007. Per- modjo S. 1993. Freshwater fishes of West- ikanan dan Kelautan Universitas Gadjah ern Indonesia and Sulawesi. Periplus Edi- Mada. MS-8:1-8. tions (HK) Ltd. Jakarta. 293 p. Tantu FY & Nilawati J. 2008. Telmatherina al- Maan EM, Hofker KD, van Alphen JJM, Seehau- bo-labiosus, a new species of sailfin silver- sen O. 2006. Sensory drive in cichlid spe- sides (: Telmatherinidae) ciation. The American Naturalist, 167(6): from Lake Matano, South Sulawesi. Wal- 947- 954. lacea, Journal of Biodiversity, 1(1):20-26. Mueller Jr R & Pyron M. 2010. Fish assemblages Weitzel DL & Pyron M. 2005. Status and eco- and substrates in the Middle Wabash River, logy of walleye (Sander vitreus) in the up- USA. Copeia, 1:47-53. per Wabash River, Indiana. Journal of Freshwater Ecology, 20(2):327-334. Nilawati J & Tantu FY. 2007. Tingkah laku re- produksi, nisbah kelamin dan struktur ukur- Whitten T, Henderson GS, Mustafa M. 2002. an Telmatherina antoniae di Danau Matano The ecology of Sulawesi. The ecology of Sulawesi Selatan. In: Isnansetyo A. (ed.). Indonesia series Volume IV. Periplus Edi- Prosiding Seminar Nasional Tahunan IV tions, Singapore. 754 p. Hasil Penelitian Perikanan dan Kelautan Wolman MG. 1954. A method of sampling co- Tahun 2007. Yogyakarta, 28 Juli 2007. Per- arse river bed material. Transactions of American Geophysical Union, 35:951-95.

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