## 4 Discussion  
The REMACAM deltaic system comprises a plain of 49,350 ha of mangroves [71] and by the year 2019, it had 3848 ha of shrimp ponds in operation [72]. It exhibited salinity values that varied from 5.15 ppt in its most internal locations to 23.7 ppt at its closest spot to the sea. On the other hand, the RVSMMC estuary, with only 3153 ha of mangroves [73], houses 6404 ha of shrimp ponds. It is a narrow system flanked by a coastal mountain range that compresses the area with mangroves towards the Muisne sector, which registered salinity values of 1.11 ppt at its innermost point and 30.5 ppt at its closest site to the sea. Several authors consider shrimp production in mangroves as unsustainable [74] given its direct relationship with the loss of these scarce ecosystems. Ecuador does not escape this reality and has the highest rate of mangrove loss in the American continents, estimated at an 80% loss of the stock of live carbon or biomass of mangrove forests on its continental coast due to the displacement of mangroves to shrimp farms [75]. There are different criteria regarding the radius of influence of the shrimp farm infrastructures in mangroves estuaries, and the environmental impact of aquatic cultures depends largely on the culture method, the stocking density, type of feeding and the hy  
Figure 9: Canonical correspondence analysis between common benthic species and quality parameters of sediments. Species code: Phyl. Sp1 = _Phyldodec_ sp1, Cap. sp = _Capitella_ sp, Peri. sp = _Perinetreis_ sp., Prion. sp = _Prionosprio_ sp., Cos. Rostrata = _Cossura rostrata_, Carc. sp = _Carcinolax_ sp., Eucly. sp = _Euclymen_ sp., Poly. Inflata = _Polymesoda inflata_, Nep. sp1 = _Nepthys_ sp1, Nep. sp2 = _Nepthys_ sp2, Ara. sp = _Arabella_ sp. drography of the culture site [76]. The changes in the TSS and organic compound content of the water are estimated to be imperceptible within 750 m of a discharge [77]. The determination of similar sites to compare systems with mangroves and shrimp farms is not simple given the great heterogeneity of the study area. The present study aimed to cover a wide range of conditions in which drainages or tidal streams of mangrove forests are useful as evidence of alterations after being modified to function as shrimp infrastructures, showing differences in the chemical state of the water and sediments as well as in the ecological state of benthic assemblages. The observed changes respond to a transformation gradient. The best condition was observed in Palma Real of the REMACAM system, which lacked shrimp production. The worst scenario occurred in Cojimies of the RVSMMC system, with the highest transformation to shrimp farms in the study area, estimated at 50% of its surface until the year 2014 [58]. The study involved four main sectors that integrated seven navigable channels at low tide, with hydrological differences related to the proximity of the outlet to the sea and whether there was an upstream connection with a freshwater course and the received flow. Inland mangrove spaces without a superficial connection to freshwater courses, known locally as \"blind\" mangroves (2 channels present in REMACAM), or those connected to small bodies of freshwater, will have greater tidal stagnation of water in dry periods. This reduces the levels of dissolved oxygen and increases the deposition of fine settleable material, such as the accumulation of leaves and mangrove wood, generating substrates loaded with more OM rich in nitrogen [78] that will have an acidic nature. This situation was known for decades. Therefore, the first shrimp farms installed in the late 1980s in RVSMMC were located near outlets to the sea with longer hours for water exchange to the ponds. This thus lowered the risk of contaminants entering from the runoff from oil palm crops, livestock activities, population centers lacking sewage treatment systems and other shrimp farms that proliferated upstream over time.