Shrimp farming and water management
Thursday early morning, last week. We drove a good 4 hours to get to Sanggalangit, a village in Buleleng. We visited a local shrimp farm that was managed and maintained by a local family. The students did learn about different aspects of Marine Pollution during their lectures at Udayana and also during their field trips. But they were not sure what to expect to learn from a shrimp farm, as none of them had ever seen an aquaculture farm before.
We were guided by the oldest son of the family. There were 5 ponds, each of them containing shrimps in different growth stages. We have learned about different aspects of water management in the shrimp farm such as water quality, water treatment and waste water. We were not surprised that antibiotic usage is still very common for the cultivation of shrimps, however, there was no indication whether these antibiotics where used as a preventative measure or as a treatment of a diagnosed bacterial disease. In addition, waste water was directly discharged into the bay. There are actually several innovative systems that could help to recycle the nutrient of the aquaculture wastewater and it definitely should be elaborated to which extend these are applicable in Bali. So, within a very short time we already had collected the main pros and cons of this shrimp farm:
We have learned that despite the positive effects shrimp farming has on the coastal communities, there are indications to an adverse effect on the coastal marine environment.
Mariculture in Bali and Marine Pollution
After lunch we headed to our next stop The Gondol Research Institute for Mariculture, located just a few kilometers to the west. The institute is known on an international level and visited by many professionals and researchers on a regular basis. The core focus is on the cultivation, and the increase of its efficiency, of several marine species such as grouper, coral trout, yellow fin tuna, abalone and a few more. As our focus of visit was not the research exactly, but more on having a look at the waste water management, we went more or less to the backyard of the buildings to investigate the drains of the seed production buildings. Algae had grown within the drains, an indicator of nutrients in the waste water. We had been looking for any kind of filtration systems to recycle the nutrients before the water is discharged into the bay, but the only tanks we could find where used to process the incoming sea water.
Nutrient pollution from mariculture and aquaculture, also known as eutrophication, is a serious pollution threat to the ocean*, and should be part of the research in this center. Also the waste water of this institute had a noticeable effect on the health of the bay according to the locals in this area. However, our guide couldn’t inform us about the exact extent of this pollution in the area.
Growing corals in North Bali
The next day we drove only 7km further from Gondol to visit the Biorock, who have been creating a vivid underwater life at Pemuteran bay. Just back in the year 2000 there has been nothing but a sand bottom in the bay, before the local community started to cooperate with Professor Wolf Hilbertz and Dr. Tom Goreau. The community agreed to make the area a pilot project for their coral reef restoration technology. A decision that not only benefited the economic situation of the area, but also the environment. With more and more artificial reef structures led into the water, a colorful coral reef grew, new fish species started to show up and so did the dive tourists. The area began to flourish both above and under water.
Sadly, 70% of the corals bleached to an increased water temperature in 2015, but is now starting to recover with the help of a dedicated team and local community on site. Is it sustainable? Yes, as long as they keep on working on more environmentally friendly ways to generate energy for the reef structures. And yes, as long as tourism practices do not interfere with the growth of a coral reef.
*Wu RSS (1999): Eutrophication, Water Borne Pathogens and Xenobiotic Compounds: Environmental Risks and Challenges; Marine Pollution Bulletin 39, p. 11-22