PRODUKTIVITAS TAMBAK TRADISIONAL PASANG SURUT DI EKOSISTEM HUTAN BAKAU BONDAN SEGARA ANAKAN JAWA TENGAH

Krisni Suhesthiningsih, S.Si, Dr. Tjut Sugandawaty Djohan, M.Sc.

2012 | Tesis | S2 Biologi

Tujuan penelitan ini adalah untuk mempelajari produktivitas tambak tradisional dengan energi pasang surut dalam satu periode budidaya udang Penaeus monodon dan ikan Chanos chanos di ekosistem hutan bakau Bondan Segara Anakan. Ukuran tambak tersebut 250m x 80m dengan satu pintu air tanpa pemberian pakan buatan. Sampling dilakukan 3 kali: sebelum benur udang ditabur, pertengahan pertumbuhan udang, dan masa panen di perairan caren, plataran tambak yang ditumbuhi 100% Fimbristylis polytrochoides, dan kali inflow. Benur ditabur 20000 ekor dan nener bandeng 2000 ekor. Parameter yang diukur adalah densitas penyusun komunitas fito dan zooplankton, pertumbuhan dan biomasa udang dan ikan. Sampel plankton komposit 20 l dicuplik dengan van Dorn 5 l, masing-masing dengan ulangan 5 – 6 kali. Kualitas air yang diukur adalah DO 24 jam, salinitas, pH, NH4, NO3, PO4, transparansi cahaya, jeluk, dan suhu dengan ulangan 2 kali. Sedangkan kualitas sedimen tambak meliputi tekstur tanah, kandungan C-organik, NH4, NO3, PO4, dan FeS2. Hasil penelitian menunjukkan adanya perubahan fungsional grup dan penurunan kemelimpahan fitoplankton secara temporal. Pada awalnya grup dominan adalah diatom pennate, >80%, dengan jenis dominan Nitzschia closterium 1350- 1874 individu per 100 l. Akan tetapi pada akhir budidaya, ada 2 grup dominan yaitu diatom pennate 33% dan alga unisel 42%. Jenis dominan alga unisel Closteriopsis longissima 237- 261 individu per 100 l. Penurunan kemelimpahan fitoplankton disebabkan oleh grazing zooplankton dan ikan C. chanos. Komunitas zooplankton tidak memiliki grup dominan, tetapi ada perubahan jenis, dari copepoda Eucyclops macrurus, 80- 528 individu per 100 l, menjadi rotifera Brachionus bidentata, 94- 118 individu 100 l-1. Perubahan jenis tersebut adalah respon komunitas plankton terhadap predasi oleh udang dan ikan, serta perubahan salinitas perairan dari 33‰ pada akhir musim kemarau menjadi 0‰ pada musim hujan. Perubahan jenis fito dan zooplankton ini tidak mengurangi kualitas pakan bagi udang dan ikan. Hal ini karena jenis- jenis plankton yang hadir disukai udang dan ikan. Kondisi perairan tambak baik karena DO selama 24 jam tinggi dengan kisaran 4,2- 7,7 ppm. Pada pertengahan masa budidaya, tambak tersebut bocor, sehingga banyak udang dan ikan keluar dari tambak. Walaupun demikian dapat dikatakan bahwa pertumbuhan dan hasil panen udang maupun ikan di tambak tradisonal pasang surut tetap baik. Biomasa panen udang dan ikan adalah 92 dan 81 kg per 0.2 ha. Kehadiran fungsional grup baik fito maupun zooplankton yang disukai udang dan ikan adalah indikator kualitas perairan tambak tradisional pasang surut sebagai ekosistem yang sehat

The purpose of this research was to study the productivity of traditional shrimp pond using tidal energies at mangrove ecosystem of Bondan Segara Anakan at one period of Penaeus monodon and Chanos chanos cultured. The size of the pond was 250m x 80m with one water inflow from Bondan River without the food supplement. Data were collected from canal, island which was dominated by 100% Fimbristylis polytrochoides of the shrimp pond, and Bondan River as water inflow. Sampling was performed 3 times: prior to juvenile of shrimp and fingerling of Chanos planted, at the middle of the growth of shrimp, and during the harvest time. The cultured pond using 20000 of shrimp juvenile and 2000 fingerlings of Chanos chanos. The parameter measured were number of species, density of phyto and zooplankton, the growth and wet biomass of shrimp and fish. The plankton samples were collected using 20 liter of composite of 5 l with modified van Dorn sampler with 5 to 6 replicates. The water qualities measured were dial DO, salinity, pH, NH4, NO3, PO4, Secchi’s depth, water level, and temperature with 2 replicates. We also measured the soil texture, C- organic, NH4, NO3, PO4, and FeS2. The results showed the changed of functional groups and the decreased of phytoplankton community temporally. At the beginning, the dominant functional group was diatom pennate, >80%, with Nitzschia closterium as the highest density, 1350- 1874 indiv. 100 l-1. At the harvest period, 2 groups of diatom pennate and unicellular algae were dominant, which were between 33% and 42%. The dominant species was Closteriopsis longissima, unicellular algae with ranged between 237- 261 indiv. 100 l-1. The decrease of the phytoplankton community were as the response to the zooplankton and C. chanos grazing. There was not functional group dominant in the zooplankton community. However there were shifted of species from copepod of Eucyclops macrurus, 80- 528 indiv. 100 l-1 to Brachionus bidentata rotifera, 94- 118 indiv. 100 l-1. These shifted of species was as the zooplankton responded to the shrimp predation, and waters salinity. The salinity of the pond was 33‰ at the end of the dry season and was 0‰ at rainy season. The changed of phyto and zooplankton were not decrease of natural food quality to shrimp and fish cultured. It was because the plankton species at whole time were the food preference of shrimp and fish. The water quality of pond was good because of the highly dial DO ranged 4.2-7.7 ppm. At the middle growth period, the pond was leak. However, the growth and yields of shrimp and fish at this traditional tidal pond were good. The yields biomass of shrimp and fish were 92 and 81 kg 0.25 ha-1. The present of phyto and zooplankton functional groups of diatom and copepod indicat

Kata Kunci : Tambak tradisional pasang surut, fitoplankton, zooplankton, udang, ikan, DO