Kemelimpahan Fitoplankton Di Perairan Ekosistem Hutan Bakau Segara Anakan, Cilacap

ACHMAD MUSTOFA HUDA, Prof. Dr. Tjut Sugandawaty Djohan, M.Sc.

2020 | Skripsi | S1 BIOLOGI

Penelitian ini bertujuan untuk mempelajari kemelimpahan fitoplankton perairan Segara Anakan di awal musim kemarau 2019. Hutan bakaunya mengalami kerusakan parah, tujuh batang pohon bakau per ha yang mengakibatkan rendahnya kontribusi seresah daun pohon bakau sebagai input nutrien. Pengambilan sampel dilakukan di perairan Bondan, Klaces, dan Kali Gatal. Pada setiap titik sampling, sampel air dicuplik menggunakan modifikasi Van Dorn 5 liter dengan volume sampel komposit 20 liter, dan dengan ulangan 5 kali. Sampel disaring dengan Wisconsin plankton net 120 micro meter. Parameter yang diukur: amonium (NH4+), nitrat (NO3-), fosfat (PO43-), sulfat (SO42-), DO, salinitas, jeluk Secchi, jeluk air, turbiditas, pH, suhu air, suhu udara, dan kecepatan arus permukaan. Hasil menunjukkan bahwa ditemukan 6 fungsional grup, 67 spesies dengan kisaran cacah individu 1-82.778 per 100L. Fungsional grup dominan adalah diatom centric dan diatom pennate, 636-9.429 dan 612-82.788 individu per 100L. Komunitas fitoplankton laut mendominasi perairan Klaces dan Kali Gatal, 68-99,49%, dan salinitas perairan 31 dan 27ppt. Spesies fitoplankton laut, Asterionella japonica mengalami peledakan di Kali Gatal, 25.805-81.898 individu per 100L. Sebaliknya, komunitas fitoplankton air tawar mendominasi perairan Bondan, salinitas perairan Bondan 9ppt, dengan spesies Oscillatoria limosa mengalami peledakan, 9.135 individu per 100L. Spesies laut, Chaetoceros lauderi juga hadir di Bondan, 9.429 individu per 100L. Kan-dungan nutrien perairan rendah, NH4+ 0,073-0,203mgL-1; NO3- 0,28-0,99mgL-1; PO4 <0,01mgL-1. Jeluk Secchi berkisar 0,44-1m. Meskipun cacah spesies fito-plankton tinggi, cacah individu fitoplankton yang hadir rendah dan terjadi peledakan A. japonica dan O. limosa. Peledakan tersebut mengindikasikan bahwa kondisi ekosistem hutan bakau Segara Anakan dalam keadaan buruk.

This research aimed to study the abundance of phytoplankton in the waters of the Segara Anakan mangrove ecosystem. The mangrove forest was severely damaged with seven mangrove trees ha-1; thus, the mangrove leaf litter as nutrient input was low. This research was carried out in Bondan, Klaces, and Kali Gatal waters. At each sampling site, a water sample of 20 liters with five replications was sampled using a modification of 5 liter Van Dorn. The water sample was filtered with a 120 micro meter Wisconsin plankton net. Parameters measured: NH4+, NO3-, PO43-, SO42-, DO, salinity, Secchi depth, water depth, turbidity, pH, water temperature, air temperature, and surface current velocity. The results showed six functional groups, 67 species that had some individuals varied between 1-82.778 per 100L. The centric and pennate diatoms dominated the community consecutively, 636-9.429, and 612-82.788 individuals per 100L. The marine phytoplankton community dominated the waters of Klaces and Kali Gatal, 68-99.49%. The salinity was 31 and 27ppt. The marine phytoplankton species, Asterionella japonica, experienced blooming in Kali Gatal at surface and bottom waters, 25.805-81.898 individuals per 100L. Freshwater phytoplankton communities dominated the Bondan waters, the salinity was 9ppt, with Oscillatoria limosa experienced blooming, 9.135 individuals per 100L. At the Bondan, Chaetoceros lauderi, a marine species, was also present with 9.429 individuals per 100L. The nutrient contents of NH4 + 0.073-0.203mg/l; NO3- 0.28-0.99mg/l; PO43- <0.01mg/l were low. Secchi depth ranges from 0.44-1m. Even though the number of species was high, but the number of individuals present was low. The blooming of A. japonica and O. limosa indicated that the waters of the Segara Anakan mangrove ecosystem were in harmful conditions.

Kata Kunci : Peledakan Asterionella japonica, Oscillatoria limosa, Cyanobacteria