The Webinar ” Water quality management in shrimp farming during the pandemic “was held on October 26, 2021 and organized by the Indonesian Shrimp Forum with four speakers, Dr. John Hargreaves from USSEC, Dr. Farshad Shishenchian from Blue Aqua, Margawan Kelana from Evergreen Fees, Liris Maduningtyas from JALA.
Dr. John Hargreaves who is currently the Aquaculture Consultant for USSEC, presented the first material of the webinar. He first explained that people need to take a probiotic approach rather than taking an antibiotic approach to cure disease in shrimp farming. This is because the current traditional and agriculture practices have been to use antibiotics. However, through some research, Dr. John’s team found that there are genes for antibiotic resistance grow in water and sediment samples in near shrimp farming areas. And this is a significant concern in the future, not only for shrimp health but also affect human health.
Dr. John then divided his presentation into several sections. The first part of the presentation was about microbial communities in shrimp ponds with different compartments, e.g., sediment, water, and intestine. Shrimps living in intimate association with their environment will have a shared community with these other elements. He then presented an example of a co-occurrence network showing how different microbial species are related in a complex community with many interactions. He further explains that the types of microbial communities shifted during the culture period. So, various factors shape the microbial community such as sediment, total organic carbon (TOC), oxidation-reduction (ORP), and Fe. These factors profoundly affect the kinds of microbes that will grow in the sediment under these different environmental conditions. So stochastic (random) processes are the main factors shaping bacterial community assembly in water and sediment of shrimp ponds.
Preceding in the discussion, Dr. John explains the factors that affect the composition of the shrimp microbiota in the intestine. One of the take-home messages here is that shrimp live in close association with the sediment. They are benthic oriented. And so, the gut microbial communities strongly are influenced and are similar to those of the sediment. Some factors affect the intestinal micro biodata composition, such as development stage, environmental element, health status, and diet components.
The third part of his presentation was about Indicators of Health and Dysbiosis. Looking at health indicators, every shrimp has this sort of healthy core called core microbiota. He said that there is a difference between the core microbiota with healthy shrimp and the diseased shrimp. The healthy community is more diverse, less complex, and its less diverse keystone taxa. The keystone species are like embryos and there are more cooperative interactions, which are the blue lines instead of a more antagonistic reaction. The diseased shrimp are red lines and so much different from blue lines, which can be used diagnostically to recognize and discriminate between a healthy and diseased shrimp.
The last part of the presentation is about the best management practices that can be put into place to stimulate a favourable microbial community. The whole idea was whether microbial best management practices would answer these practical questions: (a) is it possible to manage the bacterial assembly actively? (b) how can we do it? (c) what are the tools that we need to do that? (d) what should be the aim? (e) Should it be total health, growth, or some endpoint that we need to define and determine? This is kind of what drives this whole approach towards a probiotic or non-antibiotic approach.
- Ecological Theory as a foundation to control pathogenic invasion in aquaria
Dr. John first explains about using ecological theory as a way to address potential disease risks. Particularly those that cause an early mortality syndrome (EMS). Bacteria can be divided into two main types based on their strategies: r-strategist versus a k-strategist. They have different ecological approaches to growth. The opportunistic pathogens/r-strategist have a high growth rate. They are very competitive when resources are abundant. However, when resources are not plentiful, they are not very competitive versus the slow-growing k-strategies. The k-strategist has low competitive ability when there is a high substrate available. Still, they are much more competitive when there is a low amount of substrate available, and these are generally harmless compared to the r-strategist, which are dangerous (opportunistic pathogens).
- Bio floc system
One of the other approaches explained by Dr john is using the bio floc system. These bio floc systems as culturists can manipulate the carbon and nitrogen ratio of the inputs, which provide excellent aeration and mixing to promote the growth of heterotrophic micro-organisms. The system have many advantages across a range of aspects of the production, starting with the environment. There is a lot of nitrifying bacteria associated with these bio flocks to control the ammonia concentration. These bacteria also produce many bioactive components that are good for shrimp, immune system, digestibility, and growth. Beneficial bacteria also produce anti-microbial compounds that can affect the prevalence of pathogenic microbes in the system. So, this is another very positive approach to dealing with potential pathogens in the system, stated Dr. John.
There has been a lot written and said about probiotics, stated Dr. John. They are good for improving growth and improving shrimp health status. However, notably, this is an idea of maintaining some balanced microbial community inside the shrimp to keep pathogens that are always going to be present, to keep them under control. In addition, probiotic are very good at controlling water quality as by remediators as well.
- Phenotypic switching through quorum sensing
One of the other things is quorum sensing. Dr. John mentioned earlier that the difference between a safe vibrio and a pathogenic is that vibrio is often just a matter of density. And what happens is there is a system of communication called quorum sensing where molecules are providing signals to each other. It occurs when bacteria are released. They are communicating with each other, and the signal molecules will regulate gene expression. So, in this case, normally, this gene is repressed, however, when a sufficient number of these signal molecules are formed, it will activate these genes, and they become expressed.
The second material of the webinar titled ” Water quality management in shrimp farming during the pandemic ” was presented by Mr. Margawan Kelana from Evergreen.
Mr. Margawan discussed the competitive problem of biology or micrograms of micro-organisms. Mr. Margawan started his presentation by introducing the components of a pond ecosystem. Which consist of the sun, micro-organisms, benthos/benthic, organic ingredients, and residues of medicament/additives. Mr. Margawan stated that the ecosystem balance in an aquatic environment is needed for food and life chains in order to create a stable ecosystem.
In the second part, Mr. Margawan explained the abundance of plankton with the brightness and penetration of sunlight. The area that still allows sunlight to pass through the plankton is the respiratory area / photosynthetic area. At the same time, the area under the photosynthetic area is the respiration area or is called the dead area. Mr. Margawan pointed out that the denser the plankton content, the lower the brightness value and the more little sunlight penetration. If the plankton is too concentrated, Stratification will occur. If Stratification happens then, the water wheel must operate day and night.
In the last part of the presentation, Mr. Margawan explained that farming by using or applying constructive bacteria is to control destructive bacteria in an ecosystem. And it was implemented in a way by applying the bacteria as a competitive micro-organism. Using organic materials as a support for the action (Fermentation, minerals, lime). And lastly, Mr. Margawan strongly suggested reducing or even not using lethal chemicals, causing destructive bacteria/Vibrio and causing viruses to regenerate one day. Mr. Margawan then explained a few ways to put this solution at work:
- Build shrimp immune body
The bacteria in the shrimp’s intestines can be built to secrete enzymes that can balance the shrimp’s immune body.
- Giving treatment/treatment that is not stressful for the host
The more stressed the shrimp, the lower the body’s immune system will become. When the shrimp is weak, the bacteria begin to attack, said Mr. Margawan, based on the facts he found in the field. Frequent change of water and the need for a high enough PP are some stress drugs. And it also seems that if there are shrimp that are stressed, one example that we can see is from the meat, which is dull when stressed
- Get rid of the unneeded excretion or break it down with the intake bacteria to make it useful
It is necessary to describe the excretion of shrimp itself and from plankton/zooplankton. And also how the construction of the pond itself is structured so that everything is centralized / Setting up the water wheel so that it is centralized.
The webinar was then continued by Dr. Farshad Shinhenchian, who is the President and CEO of Blue Aqua. Dr. Farshad states that intensification of shrimp farming is the only answer to catch up with all this shrimp demand. However, intensification is not all about talking numbers only, but it is also about productivity. Nowadays, it is all about biomass or how much you can produce.
Dr. Farshad first starts his presentation by talking about carrying capacity. Carrying capacity is defined as measuring the number of individuals of any species that a particular environment can support. In other words, it refers to the maximum number of individuals that the environment can sustain. Dr. Farshad explained that traditionally on farms, people face problems after 30-40 days of stocking. Then, the pond starts to have mineral depletion, leftover feed, algae, and phytoplankton crash. Dr. Farshad explains if pond bottom is soil, it will have a poor pond bottom. There will be oxygen, toxic gas coming up, sudden changes in all the parameters in the water. Pathogenic bacteria will also come up, all of this concerning animal healthcare. And eventually leading up to the chances of mortality. All of those steps are connected, and they all depend on how you manage them.
Dr. Farshad then described that the condition of a pond is separated into three states, new (oligotrophic), middle-aged (mesotrophic), and old (eutrophic). New ponds are either freshly built or have aged slowly due to good design and proper maintenance procedures. Small ponds can be drained and cleaned every few years to reset them back to an oligotrophic stage. Middle-aged ponds have an intermediate level of nutrients and plants. They experience moderate algae blooms on an intermittent basis. And finally, the old pond. Which generally have high nutrient levels, large amounts of sludge, turbid or cloudy water, and large algae & aquatic populations.
There are four different essential cycles inside the shrimp pond and the most important one stated by Dr. Farshad is the nitrogen cycle. Most of the nitrogen inside comes from the feed, contributing a lot. Then there are feces and dead phytoplankton. The nitrogen cycle is a conversion of the organic matter through the ammonification by the heterotrophic bacteria. Oxygen is also one of the critical factors because oxygen cannot be saved, hence, the pond system always needs to have good oxygen.
In the last part of his presentation, Dr. Farshad quickly explains the mixotrophic system. Many people ask the difference between a mixotrophic system and a bio flow, stated Dr. Farshad. The mixotrophic system is a much bigger picture. Some of the benefits of mixotrophic systems are increasing carrying capacity and stocking density, reducing environmental resistance, and more. There are sectors that we have to consider about the mixotrophic system. There is pH, RBC, C: N ratio and N:P ratio. There are three stages to the process: phytoplankton stage then followed by heterotrophic bacteria and autotroph; then, the probiotic step is the last. So, these will help in terms of managing the farm and managing biomass.
The final presentation was brought by Mrs. Liris Maduningtyas, who is the CEO of JALA tech. JALA is a company that helps shrimp farmers through a shrimp culture application.
Mrs. Liris states that they are the first application to input cultivation data such as feed sampling data, mortality, disease, and other treatments. From the data that is processed through an algorithm that keeps on learning. It produces predictions, recommendations, analyses, and many more. In this seminar, Mrs. Liris discussed the technological developments in the field of digitization. Through the years, many shrimp farmers finally give in to our beneficial technology or even on any technology that makes their job trouble-free. Many data have been collected through our app, giving a better spectacle of shrimp farming. Mrs. Liris then talked about the insights in 2020. Based on JALA database the average productivity of shrimp production in Indonesia is around 12.8 tons per hectare. There will be also differences in productivity, survival rates, conversion ratios, and shrimp growth rates. There are many more features/reports based on JALA’s calculations. However, this information is generated from the Jala users only, so precautions must be needed when using JALA’s data since it cannot describe the entire shrimp industry in Indonesia. The way to get that kind of insight and predictions is through a machine that learns on and on, where any data that enters JALA anonymously will be entered into the machine for self-learning. Many features from JALA data can be used, which are helpful for all shrimp farmers, from water quality prediction to survival rate prediction, shrimp price monitoring, shrimp disease mapping, etc.