The Effect of Temperature and Food Concentration On Ingestion Rates of Quinqueloculina Seminula On the Diatom Nitzschia Closterium

The majority of sediment-dwelling foraminifera are thought to be deposit feeders. They use their reticulopodia to gather sediment with associated algae, organic detritus, and bacteria. Uptake of diatoms by foraminifera have been observed but rarely quantified. We measured the clearance (gathering) rate and ingestion rate of diatoms by the common benthic foraminifer Quinqueloculina seminula using Nitzschia closterium as prey under laboratory culture conditions. Grazing experiments were performed to evaluate the effects of temperature (at 12, 15, 18, 21, and 24°C) and food availability (10 to 800 cells mm−2) on uptake rates of diatoms. The clearance rates, estimated from the disappearance of food items, were variable (0.59–4.4 mm2 foram−1 h−1) and did not show a clear relationship with food availability. The maximum clearance rates increased from 1.80 ± 0.21 to 2.69 ± 0.32 mm2 foram−1 h−1 when temperature increased from 12 to 18°C and decreased to 2.28 ± 0.25 mm2 foram−1 h−1 at 24°C. Ingestion rates varied from 1.0 to 43 × 103 diatoms foram−1 h−1, following a hyperbolic response to food concentrations at all experimental temperatures. The maximum individual ingestion rates increased from 842 ± 180 to 1648 ± 480 (mean ± SE) cells foram−1 h−1 and then decreased to 316 ± 54 cells foram−1 h−1 as temperature increased from 12 to 24°C. Experimental results revealed that 12–18°C was the optimal temperature range for Q. seminula feeding for specimens adapted to local conditions. Our study indicates that Q. seminula plays an ecological role by feeding upon benthic diatoms in marine benthic ecosystems.

KEANEKARAGAMAN FITOPLANKTON SEBAGAI INDIKATOR TINGKAT PENCEMARAN PERAIRAN TELUK LALONG KOTA LUWUK

Penelitian ini bertujuan untuk menganalisis keanekaragaman fitoplankton sebagai indikator tingkat pencemaranperairan Teluk Lalong Kota Luwuk. Penelitian ini dilaksanakan pada bulan Februari sampai dengan bulan Mei 2015.Metode yang digunakan untuk pengambilan data dalam penelitian ini adalah metode survei dan laboratories.Pengambilan sampel fitoplankton di perairan Teluk Lalong Kota Luwuk dilakukan pada enam titik samplingmenggunakan metode sampel random. Sampel fitoplankton yang diperoleh diidentifikasi jenis fitoplankton, sedangkananalisis kuantitatif indeks biologi fitoplankton berdasarkan perhitungan keanekaragaman dari Shannon-Wiener.Perbedaan keaneka-ragaman fitoplankton yang didapatkan dianalisis secara deskriptif. Hasil analisis penelitianmenunjukkan bahwa jenis fitoplankton yang didapatkan di perairan Teluk Lalong Kota Luwuk ada 21 spesies yang secarakeseluruhan didominasi dari jenis Nitzschia closterium, Gonatozygon monotenium dan Goniodoma sp. Rata-rata nilaiIndeks Keanekaragaman dari enam stasiun (S1, S2, S3. S4, S5 dan S6) berkisar antara 0,62-1,06. Berdasarkan rata-ratanilai Indeks Keanekaragaman fitoplankton, perairan Teluk Lalong dikategorikan tercemar sedang dan tercemar berat. Data penunjang parameter kualitas air di perairan Teluk Lalong Kota Luwuk yang meliputi suhu, pH, salinitas dankecerahan masih dalam kisaran normal untuk kehidupan fitoplankton.

Trophic transfer of TiO2 nanoparticles from marine microalga (Nitzschia closterium) to scallop (Chlamys farreri) and related toxicity

In the present study, the trophic transfer of TiO2 NPs from marine microalga Nitzschia closterium to scallop Chlamys farreri was investigated. over the potential risk and environmental impact of manufactured nanoparticles (NPs) have increased in marine environments.