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DINAMIKA KOMUNITAS PLANKTON DI PERAIRAN EKOSISTEM HUTAN BAKAU SEGARA ANAKAN YANG SEDANG BERUBAH (Plankton Dynamic in the Changing Mangrove Ecosystem of Segara Anakan Central Java)

https://doi.org/10.22146/jml.18712

Tjut Sugandawaty Djohan(1*)

(1) Laboratoriurn Ekologi Fakultas Biologi Universitas Gadjah Mada, Yogyakarla 55281
(*) Corresponding Author

Abstract


ABSTRAK

Perairan hutan bakau Segara Anakan merupakan ekosistem yang sedang berubah karena sedimentasi yang tinggi sejak tahun 1980, dan telah mengakibatkan pendangkalan perainan dan mengganggu proses pasang surut. Perubahan ekosistem ini direspon oleh komunitas plankton. pada musim hujan
tabun 2002 salinitas perairannya adalah 0 0/00' dan musim kemarau 20 – 32%. Perubahan komunitas plankton tersebut dicirikan hadimya komunitas baik phyto maupun zooplankton dominan sungai pada musim hujan, dan sebaliknya komunitas laut pada musim kemarau. Pada tahun 2004, karena pendangkalan di perairan Bondan, mudflat dan perairannya dikeruk. Penelitian ini bertujuan untuk mempelajari respon komunitas phyto dan zooplankton terhadap pernbanan ekosistem pada musim kemarau Agustus 2005 di daerah tangkapan ikan nelayan perairan Segara Anakan. Hasil menunjukkan bahwa ada peledakan kemelimpahan phytoplankton yang didommasi olehl populasi Chaetoceros di perairan Bondan dan Klaces sebanyak 206890 dan 397273 individu per 100 liter, dan populasi  Asterione/lajaponica meningkat sebanyak 69778 per 100 liter di perairan Cigatal. Peledakan kedua genus tersebut adalah merupakan respon phytoplankton terhadap meningkatnya kandungan PO4 di perairan oleh pengerukan sedimen di perairan Bondan. Kenaikan P04 di perairan berturut-berturut dari Bondan ke Cigatal sebesar 4,95 ppm, 5,88 ppm, dan 4,62 ppm. Pada musim kemarau, perairan Segara Anakan juga dicirikan dengan hadimya komunitas plankton sungai yaitu sebanyak 19 species phytoplankton, dan 9 spesies zooplankton. Peledakan populasi Chaetoceros tidak direspon oleh peledakan populasi zooplankton. Keadaan ini mencerminkan bahwa kualitas perairan Segara Anakan telah menurun.

 

ABSTRACT

The mangrove ecosystem of Segara Anakan is in the process of changing to the freshwater-wetland due to the heavy sedimentation. This change was responded by the plankton communities. In the 2002 during the rainy season, the salinity was 0 0/00, and the freshwater plankton from the river dominated this mangrove ecosystem. In contrast at the dry season, the salinities were between 20 – 32 0/00, and the estuarine plankton dominated the ecosystem. In the 2004 the Bondan area became shallower and was dredged. In responding to the changing ecosystem, the phyto and zooplankton study was carried out during the dry season of August 2005 at the fishing ground of Segara Anakan. Results showed that there were blooms of phytoplankton. At the Bondan and Klaces waters, Chaetoceros dominated the communities with 206890 and 397273 individuals per 100 liter consecutively. However, at Cigatal Asterionella japonica with 69778 individuals per 100 liter dominated the community. The plankton bloom related to the intensive dredging of sediment at Bondan areas, which increased PO4 highly in the water of Bondan, Klaces, and Cigatal inconsecutively 4.95 ppm, 5.88, and 4.62 ppm. These communities were characterized by the present of 19 species of freshwater phytoplankton and 9 species of zooplankton. Even though the population of Chaetoceros was exploded, but the zooplankton community did not response to the phytoplankton increase. This indicated that the qualities of the mangrove ecosystem waters decreased, and the ecosystem was in the process of changing to freshwater-wetland ecosystem.





DOI: https://doi.org/10.22146/jml.18712

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