ERAWATI, YUNITA IKA (2022) ANALISIS KANDUNGAN NITRAT, ORTOFOSFAT DAN STRUKTUR KOMUNITAS FITOPLANKTON DI WADUK JATIBARANG SEMARANG (22m649). Undergraduate thesis, Fakultas Perikanan dan Ilmu Kelautan.

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Abstract

ABSTRAK
Yunita Ika Erawati. 26010118140056. Analisis Kandungan Nitrat, Ortofosfat
dan Struktur Komunitas Fitoplankton di Waduk Jatibarang Semarang. Churun
A’in dan Pujiono Wahyu Purnomo
Waduk Jatibarang merupakan bendungan yang menampung beberapa aliran
sungai yang kemudian menjadi sarana prasarana kegiatan akuatik serta mendukung
pariwisata yang ada. Berkembangnya aktivitas manusia di sekitar perairan waduk
seperti kegiatan pertanian, pemancingan serta pembuangan limbah rumah tangga
dapat memberikan inputan nutrien sehingga mempengaruhi kualitas perairan
waduk. Nutrien yang berperan penting terhadap kelimpahan fitoplankton adalah
nitrat dan fosfat. Tujuan penelitian ini untuk mengetahui kandungan nitrat,
ortofosfat, kelimpahan fitoplankton, mengetahui hubungan antara nitrat dan
ortofosfat dengan kelimpahan fitoplankton serta mengetahui status kesuburan di
perairan Waduk Jatibarang. Penelitian ini dilakukan di bulan Mei 2022.
Pengambilan sampel dilakukan di empat stasiun dengan tiga kali pengulangan
(pagi, siang dan sore) pada kedalaman 1,5 meter. Perhitungan konsentrasi nitrat dan
ortofosfat dilakukan dengan spektrofotometer seri Hach Programe. Analisis data
menggunakan uji regresi linier berganda untuk mengetahui hubungan antara nitrat
dan ortofosfat dengan kelimpahan fitoplankton, sedangkan analisis kesuburan
perairan menggunakan Trophic State Index (TSI) Carlson. Rata-rata kandungan
nitrat pada pagi hari sebesar 0,225 mg/L, siang hari 0,325 mg/L dan sore hari 0,275
mg/L. Rata-rata ortofosfat pagi hari sebesar 0,402 mg/L, siang hari 0,365 mg/L dan
sore hari 0,235 mg/L. Kelimpahan fitoplankton pada pagi hari berkisar antara
33.091-56.636 ind/L, siang hari berkisar 39.455-54.091 ind/L dan sore hari berkisar
31.818-40.727 ind/L. Struktur komunitas fitoplankton memiliki indeks
keanekaragaman sedang, indeks keseragaman antar jenis merata dan indeks
dominansi tidak terdapat genus yang mendominasi. Berdasarkan nilai (r) sebesar
0,376 sehingga pengaruh kandungan nitrat dan ortofosfat terhadap kelimpahan
fitoplankton menunjukkan korelasi lemah. Berdasarkan analisis TSI perairan
Waduk Jatibarang termasuk perairan eutrofik.
Kata kunci: Fitoplankton, Nitrat, Ortofosfat, Waduk Jatibarang

ABSTRACT
Yunita Ika Erawati. 26010118140056. Analysis of Nutrient Content and
Phytoplankton Community Structure in Jatibarang Reservoir Semarang. Churun
A'in and Pujiono Wahyu Purnomo
Jatibarang Reservoir is a dam that accommodates several river flows which
then become infrastructure facilities for aquatic activities and supports existing
tourism. The development of human activities around reservoir waters such as
agricultural activities, fishing and household waste disposal can provide nutrient
inputs that affect the quality of reservoir waters. Nutrients that play an important
role in the abundance of phytoplankton are nitrate and phosphate. The purpose of
this study was to determine the content of nitrate, orthophosphate, abundance of
phytoplankton, determine the relationship between nitrate and orthophosphate with
the abundance of phytoplankton and determine trophic state of the Jatibarang
Reservoir. This research was conducted in May 2022. Sampling was carried out at
four stations with three repetitions (morning, afternoon and evening) at a depth of
1.5 meters. Calculation of nitrate and orthophosphate concentrations was carried
out with a Hach Programe series spectrophotometer. Data analysis used multiple
linear regression tests to determine the relationship between nitrate and
orthophosphate and phytoplankton abundance, while trophic state using Carlson's
Trophic State Index (TSI). The average nitrate content in the morning was 0.225
mg/L, during the day it was 0.325 mg/L and in the afternoon it was 0.275 mg/L. The
average morning orthophosphate was 0.402 mg/L, 0.365 mg/L during the day and
0.235 mg/L in the afternoon. The abundance of phytoplankton in the morning
ranged from 33,091-56,636 ind/L, during the day it ranged from 39,455-54,091
ind/L and in the evening it ranged from 31,818-40,727 ind/L. The community
structure of the phytoplankton has a moderately spread index, an even index of
uniformity between species and a dominance index of no dominating genus. Based
on the value (r) of 0.376, the effect of nitrate and orthophosphate content on the
abundance of phytoplankton shows a weak correlation. Based on the TSI analysis,
the waters of the Jatibarang Reservoir are eutrophic waters.
Keywords: Jatibarang Reservoir, Nitrate, Orthophosphate, Phytoplankton

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