International Journal of Marine Science, 2025, Vol.15, No.6, 320-328 http://www.aquapublisher.com/index.php/ijms 324 5 Changes in Biodiversity and Ecosystem Services 5.1 Positive and negative impacts on benthic faunal diversity Not all sea cucumber farming can bring ecological benefits. In some systems, the activities of sea cucumbers can indeed have positive effects. For example, during the process of feeding and turning the sediment, they can promote nutrient cycling, reduce the accumulation of organic matter, and provide more "breathing space" for benthic animals (MacTavish et al., 2012). In such environments, not only benthic small animals, but also the diversity and number of some symbiotic species and upper-middle consumers may increase. Even some studies suggest that sea cucumbers have indirectly helped seagrass, promoting the growth of primary producers and driving greater ecosystem vitality (Arnull et al., 2021). However, to be fair, if the density is too high or management is inadequate, the situation will change. Sediments may become more compact, oxygen deficiency may intensify, and diseases may also breed easily. In such environments, some sensitive benthic species may be suppressed instead. Whether it is good or bad depends on the local environmental conditions, the stocking density and the specific type of sea cucumber (Namukose et al., 2016). 5.2 Shifts in ecosystem services: bio-cleaning vs. ecological disturbance It is often said that sea cucumbers are natural "scavengers". Indeed, they perform well in cleaning up sediment and stabilizing water quality. Especially in multitrophic systems such as IMTA, the addition of sea cucumbers can significantly slow down the trend of eutrophication and help nutrients re-flow in the system (Purcell et al., 2016; Zamora et al., 2018). However, this "cleaning effect" is not without conditions. Once the system becomes closed, overly dense or has management problems, the original ecological services may turn into sources of interference. For instance, excessive disturbance of the sediment, rapid release of nutrients, and even the accelerated spread of certain diseases within the system. That is to say, the ecological services brought by sea cucumbers cannot be simply regarded as a "universal tool". Appropriate design and early warning mechanisms are still necessary. 5.3 Estimation methods for ecological thresholds and environmental carrying capacity How many sea cucumbers can a system actually raise? It is unlikely that there will be a uniform answer to this question. The differences can be quite significant in different places and under different conditions. But there had to be an explanation, so the researchers tried every possible way to "calculate". Some use models, such as the individual energy flow model, or ecosystem tools like Ecopath with Ecosim; Some people simply conducted on-site tests to see how the environment reacted and whether the number of species changed after placing a certain amount (Chary et al., 2020; Wang et al., 2022; Grosso et al., 2023). There is also life Cycle assessment (LCA), which is more comprehensive. It measures whether the system is on the verge of collapse from aspects such as energy and water usage, and nutrient flow. Ultimately, calculating all this is not to arrive at a fixed figure, but to figure out at which point the benefits of bioremediation will be offset by potential risks. Some environmental factors cannot be ignored either, such as the speed of water flow, the abundance of food, and those ecological changes that gradually accumulate. All these may cause the so-called "optimal density" to fluctuate. Therefore, carrying capacity is not a matter of making a guess based on formulas, but rather depends on whether it aligns with the actual situation. 6 Case Studies 6.1 Sediment impact assessment of pond-based sea cucumber farming in Indonesia In Indonesia, when it comes to pond sea cucumber farming, many people's first reaction is that it is quite helpful for the bottom sediment, especially for those farms with low farming density and sufficient daily maintenance. Indeed, the substrate can become cleaner and organic matter is less likely to accumulate. But things don't always go so smoothly. Once the breeding density exceeds that "appropriate range", especially after artificial feed is started to be used, the mess at the bottom begins to become troublesome. Organic matter begins to accumulate, the water quality becomes cloudy, and the sedimentary layers outside the aquaculture area may also encounter problems. However, these changes may not be immediately apparent; sometimes they occur quietly. However, there is another point that is often overlooked, which is that the structure of the pond itself is also "affected". Once the facilities are set up, the direction of water flow and the location of sediment deposition will
RkJQdWJsaXNoZXIy MjQ4ODYzNA==