## 4 Discussion
### Developing Restoration or Mitigation Mechanisms by Using ISs  
Integrating the ideas of previous studies [35; 36], more complex conditions will be presented to select ISs. Another approach, trait-based metrics, can also be used to select ISs, where assemblages respond to a gradient of environmental degradation. The functional trait method can also screen out good candidates and ISs that are of ecological significance for biomonitoring and are broadly applicable over biogeographic boundaries [55; 56]. In this context, the complex factor with the selection of ISs can be expressed in terms of its concept as follows:  
\[\text{Selection of indicator species = maximum or minimum_integrated function (species trait, species abundance, } \tag{11}\] \[\text{time, place, and environment factor}\]  
The habitat evaluation procedure (HEP) for formulating a restoration or mitigation project was developed and is shown in Figure 4. Firstly, this procedure combines the quantitative method of the indicator species from the environmental monitoring plan to select ISs. Second, it analyzes the relationship between the species and the environment after the selected ISs. The biological coefficient can be obtained with the environment or biological parameters with engineering. Finally, this information can be used to develop rehabilitation or recovery plans. When government managers formulate restoration or rehabilitation projects, collecting biological information and understanding the meaning of environmental habitat is an important first step. In particular, in the engineering design stage, the environmental or engineering parameters must be obtained from the biological coefficient, as shown in Figure 4. Therefore, engineering designed in this way is also called ecological engineering and considers biological and ecological significance. It is crucial that clear biological coefficients can be obtained after determining ISs. Engineering parameters include porosity, the surface roughness of structure, and the particle size of the bottom substrate. From these, it can be determined whether the sediment is mud or hard soil, which originates from the consideration that the habitat choice is a mudflat or mangrove. Overall, almost 80% of studies on ISs have used multiple species within the same taxa or a cross-tax index as indicators [15]. Almost all pertinent studies on ISs have been descriptive field investigations and have selected numerical dominants in areas that differ widely in terms of environmental gradients [29; 57]. In this study, we developed a new  
Figure 4: A mechanism and procedure for formulating a rehabilitation of mitigation project by using indicator species. calculation method that incorporates a higher probability of contributing to biodiversity across taxonomic groups based on IS analyses. Specifically, the concept of ISs is based on the hypothesis that environmental shifts are reflected by changes in the diversity, abundance, or growth rate of species [11; 12; 13; 14]. Therefore, ISs are usually employed for monitoring in the fields of wildlife conservation, habitat management, and ecological restoration [58; 59; 60; 61]. Our results demonstrate that some taxonomic groups contribute significantly more to biodiversity than others. The evaluation of conservation or restoration requires a holistic approach that integrates the consideration of several endpoints on different scales (target species, indicator groups, and an ecosystem scale) [62]. In this paper, ISs were selected to assess environmental changes after mangrove removal. The combination of various approaches and their integration into holistic perspectives is required so that an understanding of ISs and the biodiversity of marine ecology can be further developed. We further confirmed that the relationships between biodiversity and ISs are crucial for coastal management.