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ABSTRACT

Abstract. Muhtadi A, Pulungan A, Nurmaiyah, Fadlhin A, Melati P, Sinaga RZ, Uliya R, Rizki M, Rohim N, Ifanda D, Leidonald R, Wahyuningsih H, Hasani Q. 2020. The dynamics of the plankton community on Lake Siombak, a tropical tidal lake in North Sumatra, Indonesia. Biodiversitas 21: 3707-3719. The tidal lake is a very dynamic estuary ecosystem and very vulnerable to environmental stresses and disturbances. Plankton is an aquatic organism that is very easily affected by environmental pressures and disturbances. This study aimed to reveal the phenomenon of plankton dynamics in tropical tidal lakes in Indonesia. The study was conducted at Siombak Lake from September 2018 to August 2019. Data were collected at high and low tides every month during the full month. The data analysis included plankton abundance, diversity index, and the relationship between water quality and plankton with PCA and succession analysis. The results showed that in Siombak Lake was found 66 genera which consisted of 54 phytoplankton genera and 12 zooplankton genera. Plankton abundance is higher in parts of the lake (stations 1-8) than in the river (stations 9-11) at both high and low tide. Temporally it shows that plankton abundance is higher in the rainy season (Feb-Aug, outside May) than in the rainy season (Sep-Jan, and May). Spatially, plankton in Siombak Lake at high tide is more influenced by TSS, phosphate, and salinity, while at low tide, it is influenced by TSS, Water transparency, BOD, silicate, salinity, and dissolved oxygen. Temporally, plankton in Siombak Lake at high tide is more influenced by salinity, conductivity, Debit, TSS, and salinity, while at low tide, it is influenced by salinity, conductivity, turbidity, TSS, TDS, DO, BOD, and COD. Based on the plankton Frontier succession graph, it shows that Siombak Lake is included in stage 1 and stage 2. Stage 1 occurs before the rainy season (August-September) and the peak of the dry season (March-April).

Sand mining activities in Pasir Sakti District, East Lampung Regency, have changed the landscape and the allotment of land around it. The former sand mining area now becomes large puddles that are not utilized. This study aimed to analyze the suitability of water quality in ex-sand mining areas for tilapia (Oreochromis niloticus) culture. Observations were carried out at three stations in January-October 2019. Water quality measurements were performed to check water depth, clarity, temperature, current, dissolved oxygen, pH, salinity, nitrate, phosphate, iron, sulfate, and phytoplankton density. Analysis of suitability for aquaculture was carried out using weighting and scoring methods. Based on the results of the suitability analysis, the scoring result of the sand mining land for O.niloticus culture was in the range of 64% -68%. This score is classified as marginally suitable. The parameters with low scores are clarity, dissolved oxygen, temperature, pH, ammonia, phosphate, and iron (Fe) concentration parameters. Meanwhile, salinity, nitrate, sulfate, and phytoplankton density indicate conditions that are suitable for aquaculture. Therefore, severe treatment is needed to improve water quality to make it ideal for O.niloticus culture.

Phytoremediation is one effective method used for reducing the iron (Fe) from waters. Azolla pinnata is a plant that has potential as an agent of phytoremediation of Fe in waters. This study aims to verify the ability of Azolla pinnata to reduce Fe from sand excavated water in Pasir Sakti District, East Lampung Regency, Indonesia. The study was conducted with three treatments. The treatments of 25% cover area, 50% cover area, and 75% cover of Azolla pinnata, with three replications each. The experiments were carried out until the water quality became suitable for aquaculture. The results showed that the area cover of Azolla pinnata had a different effect (P <0.05) on the decrease in iron concentration in the water. The treatment with 75% cover area of Azolla pinnata, showed a reduction percentage of iron concentration of 98.10%. It is the most significant reduction percentage of iron. Whereas the treatment with 25% and 50% Azolla pinnata cover area of succeeded in reducing the concentration of Fe in water 92.5% and 93.3% respectively.

Abstract. Hasani Q, Yusup MW, Caesario R, Julian D, Muhtadi A. 2022. Autoecology of Ceratium furca and Chaetoceros didymus as potential harmful algal blooms in tourism and aquaculture sites at Teluk Pandan Bay, Lampung, Indonesia. Biodiversitas 23: 5670-5680. Harmful algal blooms (HABs) phenomenon has been observed around tourism and aquaculture sites in Teluk Pandan Waters, Lampung Bay. The dominant potential HABs found in Teluk Pandan waters were Ceratium furca and Chaetoceros didymus. This study aimed to analyze the relationship between the environmental physicochemical factors and the abundance of C. furca and C. didymus as potential HABs. Phytoplankton samples were collected from four stations (Hurun Bay, Sidodadi Coastal Waters, Sari Ringgung Beach and Cikunyinyi Bay) during May-August 2022. Physical parameters (temperature, depth, brightness, current velocity and salinity), as well as chemical parameters (dissolved oxygen, pH, phosphate, nitrite, nitrate and ammonia) were all measured in conjunction with phytoplankton sampling. Canonical correlation analysis and multiple regression were used to predict the effect of environmental parameters on phytoplankton density. Blooms of C. furca were found with the highest density at 5.417×106 cells/L in Cikunyiyi Bay, while C. didymus predominated in Hurun Bay (2.890×104 cells/L), Sidodadi Coastal Waters (3.923×104 cells/L) and Sari Ringgung Beach (3.531×104 cells/L). The main factors influencing the increase in C. furca population at Cikunyinyi Bay were pH, phosphate and nitrate. The increase in C. didymus population at Sidodadi Coastal Waters was affected by phosphate, nitrate and nitrite, while phosphate and nitrate influenced the increase in C. didymus population at Sari Ringgung Beach. Potentially HABs density was found to be higher near intensive shrimp farming sites. The use of fertilizer and artificial feed in high quantities is thought to be responsible for increased water eutrophication. Periodic monitoring and consistent determination of environmental carrying capacity for intensive shrimp farming activities are required to control HABs and ensure the sustainability of aquaculture and tourism activities in Teluk Pandan Waters.

Hasani Q, Pratiwi NTM, Wardiatno Y, Effendi H, Martin AN, Efendi E, Pirdaus P. 2020. Phytoremediation of Iron (Fe) in Ex-sand Mining Waters by Water Hyacinth (Eichhornia crassipes (Mart.) Solms). The high concentration of iron (Fe) has allegedly caused the water quality of puddles at sand mining area. The poor water quality, in which high contentrations of iron will to a reduction in aquaculture production. This study verified the ability of water hyacinths (Eichhornia crassipes (Mart.) Solms.)) as a phytoremediation agent for iron (Fe) concentration in water at the sand mining area, in East Lampung Regency, Indonesia. The study was carried out with 3 treatments and 3 replication each, including the treatment of (i) 25% water surface coverage, (ii) 50% water surface coverage, and (iii) 75% water surface coverage of water hyacinth. Measurement of Fe concentrations, bioconcentration factor (BCF) and translocation factor (TF) once a week, until Fe concentrations in water are adequate for aquaculture. This was achieved for 21 days. The results showed that the highest percentage reduction of Fe (97.49%) was observed at water hyacinth cover area 50%. The highest value of BCF was 2385.51, while the highest TF was 1.14 in stems and 1.02 in leaves. The results of this study open up opportunities for use water in ex-sand mining areas for aquaculture by the community and its management by the Government of East Lampung Regency, Lampung, Indonesia.

Tembakang Fish (Helostoma temminckii) is one of the fish that have high economic value in Rawa Bawang Latak. Overfishing and the introduction of fish resulted tembakang number of fish populations decline, so it takes the efforts of domestication. This study aims to determine the growth pattern that includes tembakang fish length and weight relationships, growth parameters, and factor conditions. Research carried out for four months, ie in October 2013 -January 2014. Tembakang fishing done at two stations in Rawa Bawang Latak. The sampling frequency of fish is done only once a month using Sero. The results showed that the pattern of growth tembakang fish is allometric positive, condition factor values male and female fish were not significantly different, female tembakang fish growth faster than the male fish, fish tembakang males on the size of 180.6 mm was 21 months, while females in size 191.1 mm 8 months old. PENDAHULUANKabupaten Tulang Bawang memiliki daerah aliran sungai yang luas ± 100 Ha. Salah satu daerah aliran sungai yang menjadi habitat banyak jenis ikan adalah Rawa Bawang Latak. Rawa Bawang Latak merupakan daerah aliran sungai yang berasal dari Sungai Miring di daerah Kotabumi Lampung Utara dan Sungai Bakung di daerah Kabupaten Lampung Tengah, yang melewati Kabupaten Tulang Bawang, Kota Menggala, hingga bermura ke Sungai Tulang Bawang.Rawa Bawang Latak mempunyai potensi berbagai jenis ikan yang memiliki nilai ekonomis yang cukup tinggi, salah satunya adalah ikan tembakang (Helostoma temminckii). Ikan ini biasa disebut dengan kissing gurame, karena bentuk tubuhnya mirip dengan ikan gurame. Ikan ini dimanfaatkan oleh masyarakat diantaranya sebagai bahan pakan untuk ikan pada keramba jaring apung, namun telur ikan tembakang (Helostoma temminckii) dimanfaatkan dalam acara adat Lampung untuk pemberian bekal keberangkatan haji. Hal ini yang menyebabkan telur ikan tembakang menjadi mahal, harganya mencapai Rp 250.000/Kg.