Wetlands cultivation or farms is an important sector that contributes to food supplies in Indonesia. This sector has enormous potential since 70% of Indonesia's area is covered by water. Aquaculture fisheries production in Indonesia reached 16,675,031 tonnes in 2016 and increased every year (Statistics Indonesia, 2016).
Aquaculture fisheries sector is generally managed in a traditional way, both monocultural or polyculture. However, the number of farms that are intensively managed keeps increasing nowadays. One of many parameters that affect cultivation is phytoplankton (algae) which has a great impact on water quality, including on traditional and intensive farms (Utojo, 2015).
Phytoplankton is a type of plankton that becomes the primary producer in waters. Phytoplankton serves as the first link in water's food chain so it is called the primary producer. Aside from its role as the primary producer in farm waters, phytoplankton also has other benefits, namely:
Phytoplankton population is highly affected by light intensity, temperature, and nutrient content in the waters. Nutrient concentrations such as nitrogen (N) and phosphorus (P) can trigger blooming algae or eutrophication. Eutrophication is the increase of phytoplankton density and has a bad impact on the quality of waters.
Several cases of algae blooming that occur in pond waters may kill most of the fish and shrimp. This is due to the great amount of algae that causes a significant decrease in dissolved oxygen levels in the waters. Algae blooming is a case that often occurs in intensive farms due to the fertility of the pond bottom caused by the accumulation of shrimp feces and feed residue.
Traditional farming is a technique that was first practiced by farmers long ago. Nevertheless, this technique is still practiced by farmers until now. Traditional farming technique does not require feeding or treatment, but it only uses the most of the tidal conditions and natural feed. Water in the estuary will continue the tide at the entrance to the pond for nutrients exchange.
Even though traditional farmers can still be found, they are no longer interested in using traditional farming because of its low productivity. Nowadays, most of the farmers manage their farms in a traditional semi-intensive way.
The traditional semi-intensive farming technique uses water channels or irrigation from the estuary to farm area. Water that flows into the farm area is then blocked to prevent high or low tide from affecting it. This technique is almost identical to the traditional farming technique. The distinction is that nutrients and plankton do not occur naturally. In semi-intensive farms, fertilization is done at the start of the preparation period using 400-1000 kg/ha of organic fertilizer, 200-400 kg/ha of urea, and 100-200 kg/ha of SP36. This fertilization process is done to maintain the amount of plankton in the pond.
Intensive farming is a fishery farming technique which continuously gives feed into the pond as the main food source for shrimp. However, phytoplankton in intensive farms often cause serious problems. One problem that often occurs is algae blooming. Algae blooming is a case that often occurs in intensive farms due to the fertile pond bottom caused by the accumulation of shrimp feces and feed residue.
Even though intensive farms have great benefits, many intensive farmers experience losses. This loss is caused by shrimp diseases and death. Poor water quality that occurs in intensive farms is caused by low oxygen levels and extremely high turbidity.
One of the measures to control water quality is by installing paddle wheels in intensive ponds. Paddle wheel is a technology that can keep up with the need for oxygen. In order to speed up the diffusion process, control the position of organic deposits or feed residue and feces, the paddle wheel functions as a stirrer for dissolved oxygen. Besides paddle wheel, water exchange is also done by draining the water through the bottom of the pond regularly. Hence, dirt, feed residue, and feces that deposit can also be drained. This water exchange process can enhance the quality of farm waters.
A successful intensive farm has a better water quality, higher phytoplankton abundance, and greater yields. The high abundance of the phytoplankton community is a sign of good water quality that can support farm production.
Intensive farms can generate greater income than traditional farms. However, the costs necessary to manage intensive farms are definitely higher. A study regarding the comparison of cost and income of traditional and intensive farms in Situbondo, East Java in March-August 2017 shows that the total costs of traditional farms is IDR 51,749,504 and its net profit is IDR 61,317,112. Meanwhile, the intensive farms cost IDR 630,865,592 with IDR 727,773,104 in net income.
Although intensive farms have greater advantages compared to traditional farms, intensive farms have a worse impact on the environment. This is due to the direct dumping of feed and feces waste from intensive shrimp ponds into rivers, estuaries, and other waterways, which lowers the quality of the water. One of the cases that happened is the impact of intensive shrimp farms in Banyuputih, Situbondo Regency, East Java that caused high concentrations of TSS and COD in coastal waterways exceeding the threshold.
Get notifications on cultivation tips, feature and service updates, as well as JALA's latest activities.