Rawa pesisir merupakan rawa pasang-surut bagian dari ekosistem estuari. Rawa pesisir di Sungai Cimandiri Kabupaten Sukabumi, Jawa Barat merupakan salah satu ekosistem estuari yang memiliki peran ekologi yang penting untuk kehidupan biota air yang menetap maupun yang bermigrasi seperti ikan sidat. Penelitian ini bertujuan untuk mengkaji fungsi rawa pesisir, biologi populasi sidat dan faktor lingkungan yang berpengaruh terhadap populasi sidat Penelitian dilakukan secara parsial pada September-Oktober 2016, Maret dan Desember 2017 dan January-November 2018. Penangkapan ikan sidat dan pengukuran kualitas air dilakukan pada 4 lokasi terpilih berdasarkan kondisi habitat yang berbeda. Penangkapan ikan sidat dilakukan pada malam hari dengan alat tangkap pancing dan bubu. Sidat yang tertangkap terdiri dari 2 jenis yaitu Anguilla bicolor bicolor (107 individu) dan Anguilla marmorata (4 individu). Panjang total A. bicolor bicolor adalah 15,7-57,0 cm dan berat 5,8-347,2 g dan panjang total A. marmorata adalah 17,0-29,5 cm dan berat 6,9-33,7 g. Pola pertumbuhan sidat (A.bicolor bicolor) di rawa pesisir adalah allometrik negatif, dengan nilai faktor kondisi 0,99-1,03. Sidat di rawa pesisir banyak tertangkap di daerah rawa pesisir yang dalam dan terdapat tumbuhan air. Berdasarkan analisis PCA (Principal Component Analysis), preferensi keberadaan sidat di rawa pesisir dicirikan oleh parameter kedalaman, kecerahan, salinitas, dan kecepatan arus. Rawa pesisir diketahui berfungsi sebagai habitat bagi ikan sidat muda (yellow eel) pada fase estuarine.
Rainbow selebensis (Telmatherina celebensis) adalah salah satu jenis ikan endemik di Danau Towuti. Ikan tersebut memiliki warna tubuh yang indah dan berpotensi sebagai ikan hias air tawar yang bernilai ekonomis. Dikhawatirkan akan terjadi penurunan populasi ikan tersebut di alam akibat perubahan lingkungan dan penangkapan ikan yang intensif. Penurunan kualitas lingkungan tersebut secara tidak langsung berkaitan dengan penebangan hutan. Penelitian ini bertujuan untuk mengetahui distribusi spasial dan temporal ikan Rainbow Selebensis. Penelitian dilakukan di perairan Danau Towuti dari bulan Maret 2002 sampai dengan April 2003. Ikan ditangkap menggunakan jaring insang eksperimental (experimental gill net) dengan 4 ukuran mata jaring yaitu ¾, 1, 1¼, dan 1½ inci di 4 stasiun. Hasil penelitian menunjukkan bahwa ikan Rainbow selebensis berdistribusi luas di perairan Danau Towuti mulai dari wilayah litoral sampai dengan ke tengah danau. Jumlah ikan yang diperoleh lebih banyak dan ukuran ikan juga lebih bervariasi di stasiun yang terdapat tanaman air (stasiun I dan IV) dibandingkan di stasiun yang tidak terdapat tanaman air (stasiun II dan III). Distribusi ikan secara spasial dipengaruhi oleh kedalaman air dan tanaman air, sedangkan secara temporal dipengaruhi oleh ketinggian muka air, oksigen terlarut, dan pH. Puncak kelimpahan ikan ini ditemukan pada bulan Nopember. Rainbow selebensis (Telmatherina celebensis) is an endemic species in Lake Towuti. This species has excellent body color, which is commercialized as ornamental fishes. Concerning will be decress fish population due to change of environment and intensive fishing. Degradation of the environmental quality indirectly related the deforestation. The aim of this research is to obtain information on spatial and temporal distribution of Rainbow Selebensis in Lake Towuti on March 2002 until April 2003. The fish was captured with experimental gill net mesh size 0.75; 1; 1.25; and 1.5 inches at four stations. The result shows that Rainbow Celebensis has wide distribution in Lake Towuti from litoral zone until the middle of lake. At station where there are aquatic plant (station I and IV), the number and size of the fish were high and various compared to station where there were aquatic plant (station II and III). Spatial distribution of Rainbow selebensis was influenced by depth of water and existence of aquatic plant, while temporal distribution was influenced by water level, dissolved oxygen, and pH. The peak season abundance of the fish was in November.
The conventional method for cadmium removal in aqueous solutions (1–100 mg/L) is ineffective and inefficient. Therefore, a batch biosorption reactor using a local freshwater microalga (originating from an urban lake, namely, Situ Rawa Kalong-Depok) as dried biosorbent was tested. Biosorbent made from three kinds of cyanobacterium Aphanothece sp. cultivars (A0, A8, and A15) were used to eliminate cadmium (Cd2+) ions in aqueous solution (1–7 mg/L). The biosorbents were harvested from a photobioreactor system enriched with carbon dioxide gas of 0.04% (atmospheric), 8%, and 15% under continuous light illumination of about 5700–6000 lux for 14 d of cultivation. Produced dried biosorbents had Brunauer–Emmet–Teller (BET) surface area ranges of 0.571–1.846 m2/g. Biosorption of Cd2+ was pH and concentration dependent. Sorption was spontaneous (ΔG = −8.39 to −10.88 kJ/mol), exothermic (ΔH = −41.85 to −49.16 kJ/mol), and decreased randomness (ΔS = −0.102 to −0.126 kJ/mol. K) on the interface between solid and liquid phases when the process was completed. The kinetic sorption data fitted best to the pseudo-second-order model (k2 = 2.79 × 10−2, 3.96 × 10−2, and 4.54 × 10−2 g/mg.min). The dried biosorbents of A0, A8, and A15, after modeling with the Langmuir and Dubinin–Radushkevich isotherm models, indicated that cadmium binding occurred through chemisorption (qmax, D-R = 9.74 × 10−4, 4.79 × 10−3, and 9.12 × 10−3 mol/g and mean free energy of 8.45, 11.18, and 11.18 kJ/mol) on the monolayer and homogenous surface (qmax, Langmuir of 12.24, 36.90, and 60.24 mg/g). In addition, the results of SEM, EDX, and FTIR showed that there were at least nine functional groups that interacted with Cd2+ (led to bond formation) after biosorption through cation exchange mechanisms, and morphologically the surfaces changed after biosorption. Biosorbent A15 indicated the best resilient features over three cycles of sorption–desorption using 1 M HCl as the desorbing eluent. These biosorbents can be a potent and eco-friendly material for treating aqueous wastewater.
Abstract. Wetlands are important reservoirs of water, carbon and biodiversity. They are typical landscapes of lowland regions that have high potential for water retention. However, the hydrology of these wetlands in tropical regions is often studied in isolation from the processes taking place at the catchment scale. Our main objective is to study the hydrological dynamics of one of the largest tropical rainforest regions on an island using a combination of satellite remote sensing and novel observations from dedicated field campaigns. This contribution offers a comprehensive analysis of the hydrological dynamics of two neighbouring poorly gauged tropical basins; the Kapuas basin (98 700 km2) in West Kalimantan and the Mahakam basin (77 100 km2) in East Kalimantan, Indonesia. Both basins are characterised by vast areas of inland lowlands. Hereby, we put specific emphasis on key hydrological variables and indicators such as discharge and flood extent. The hydroclimatological data described herein were obtained during fieldwork campaigns carried out in the Kapuas over the period 2013–2015 and in the Mahakam over the period 2008–2010. Additionally, we used the Tropical Rainfall Measuring Mission (TRMM) rainfall estimates over the period 1998–2015 to analyse the distribution of rainfall and the influence of El-Niño – Southern Oscillation. Flood occurrence maps were obtained from the analysis of the Phase Array type L-band Synthetic Aperture Radar (PALSAR) images from 2007 to 2010. Drought events were derived from time series of simulated groundwater recharge using time series of TRMM rainfall estimates, potential evapotranspiration estimates and the threshold level approach. The Kapuas and the Mahakam lake regions are vast reservoirs of water of about 1000 and 1500 km2 that can store as much as 3 and 6.5 billion m3 of water, respectively. These storage capacity values can be doubled considering the area of flooding under vegetation cover. Discharge time series show that backwater effects are highly influential in the wetland regions, which can be partly explained by inundation dynamics shown by flood occurrence maps obtained from PALSAR images. In contrast to their nature as wetlands, both lowland areas have frequent periods with low soil moisture conditions and low groundwater recharge. The Mahakam wetland area regularly exhibits low groundwater recharge, which may lead to prolonged drought events that can last up to 13 months. It appears that the Mahakam lowland is more vulnerable to hydrological drought, leading to more frequent fire occurrences than in the Kapuas basin.
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