# Lessons for Coastal Applications of IMTA as a Way towards Sustainable Development: A Review
## 6 Bioremediation by Extractive/Additional Species  
Bioremediation through integrated, ecosystem-based aquaculture is an important potential of integrated cultivation [6]. In recent years, water quality difficulties created by aquaculture wastes have received much interest [21; 40; 121]. On its own, the application of biofilters (sea cucumber bivalves) to mitigate effluents can increase economic benefits. In integrated aquaculture, waste nutrients are not a burden but a resource for the supplementary cultivation of products that also act as biofilters. Verongiida marine demosponges are a material science and marine pharmacological gold mine [122]. Sustainable approaches to construction can use Verongiida demosponges' biomaterial, and there is anti-cancer therapeutic potential. The co-cultivation of Verongiida (_Aplysima aerophoa_) in IMTA systems could thus be a viable option to improve both ecological sustainability and profit at the farm level [123; 124]. Bivalves are a top candidate as extractive species in IMTA [125]. They catch waste particles from agricultural effluent and extract waste products from a higher trophic level (e.g., bacteria, phytoplankton). Grown together, _Gracilaria_ sp. and _Fenropeaneus indicus_ at different stocking densities showed that the seaweed removes nutrients from shrimp farm waste. 600g of seaweed removed 25% of ammonia, 22% of nitrate, and 14% of phosphate from 200g of shrimp waste at a 3:1 ratio of _Gracilaria_ sp. and _Fenropeaneus indicus_[6]. Bivalves are biocontrolless of sludge for fish farms and other sources of eutrophication. The capacity of _Diplodon chilensis_ freshwater mussel to mitigate chlorophyll a, phosphate, and ammonia in salmon tanks has been demonstrated [126]. _Cucumaria fondosa_ exhibits a high absorption efficiency (>80%) when exposed to higher organic particulate matter, such as salmon food and faeces, so that it is an effective organic extractive species for IMTA systems. Bivalve cultivation can, therefore, be combined with fish farming to reduce the negative effects on the environment, while simultaneously offering a commercially successful crop for farmers [86]. Bivalves such as mussels, oysters, and clams as bio-filters in estuaries have shown a positive effect on nutrient-rich effluents. In IMTA, the cultivation of bivalves (_Crassostrea madrasensis_) and finfish (_Etroplus suratensis_) effectively controlled eutrophication [127; 128]. The filter-feeding oysters enhanced the water quality in the farming region, consequently lowering eutrophication. In this farming technique, the best ratio of fish to oysters reported for co-cultivation was 1:0.5 [127; 128]. A study on the integrated cultivation of macroalgae (_Saccharina latisima_) and mussels (_Mytilus galloprovincialis_) in the Sea of Galicia, Spain found that it was more productive than individual crops, and therefore IMTA systems could serve to diversify aquaculture and reduce environmental impact. Mussels' metabolism produces organic and inorganic waste. Mollusc-excreted ammonia helps algae thrive and improves water quality [129]. In order to develop such bioremediation systems, it is essential to choose suitable seaweed species. In IMTA, seaweeds can mitigate the environmental impact of nitrogen-rich effluents on coastal ecosystems. The seasonal distribution and productivity of seaweeds are influenced by water temperature and photoperiod [130]. In a study in Korea, ([PERSON], Busan) [130], identify, _Codium fragile_ as an ideal candidate for summer IMTA because it grows during late summer and early fall and thus should be able to absorb substantial amounts of nutrients from fed aquaculture when water temperatures are warmer. Another study argues that it is difficult to analyse the bio-mitigation effect of extractive species in open-water studies because the Initial Biomass Ratio (IBR) of the extractive to target species is too small. This makes it difficult to conduct experiments.