###### Abstract  
The environmental quality of mangroves is influenced by multiple factors, among which shrimp aquaculture currently plays a major role. This study describes the alterations of natural conditions of mangrove systems that house shrimp farms in the northern Ecuadororean coast. Water, sediment quality and the structure of benthic assemblages of four sectors with different proportions of mangroves and shrimp ponds are described. The samples were collected at the confluence of mangrove drainagees or tidal creeks, as well as in the modified drainages for shrimp farm infrastructures towards navigable channels, during the dry and rainy seasons. Shrimp farm drainage water had a 17% higher dissolved oxygen concentration and 2.5 times higher total ammonium and phosphorus compared to mangrove drainage water. The sediment in the latter decreased their total organic matter and nitrogen content by 44% and 53%, respectively, slightly increasing the pH level and increasing the ammonium content by 93%. Furthermore, the redox profiles were different between the types of drainages. The soft-bottom benthic assemblages involved 56 species in the study area and exhibited a variety of sectoral structures, with better indicators of ecological status in sectors with fewer shrimp farms. Finally, improvements are suggested for monitoring the environmental quality of shrimp farms in Ecuadoran mangrove systems. hydrography; aquaculture impacts; sediment carbon loss; AMBI index 2023 13749  
in hydrology [4], salinization [15; 16], the introduction of non-native species [17], and disease outbreaks [18; 19]. Other issues include the pollution from effluents, chemicals and drugs [20], the use of wild fish for feed [21], the capture of wild shrimp seed and the loss of livelihoods and social conflicts which may arise therof [22; 23]. Due to growing concern about climate change, several studies have quantified the effects of the mangrove conversion to shrimp ponds on the soil carbon stocks [24] and greenhouse gas emissions [25; 26]. Shrimp farming employs ponds with a flow-through system that uses water exchange rates to maintain optimal hydrological and biological parameters for the shrimp culture [27]. The water used in the ponds will have physicochemical and biological alterations since effluents of shrimp farms add nutrients, organic matter and suspended solids to the receiving water bodies [28; 29]. Pond sediments therefore were high in the concentration of nutrients, organic matter, and the density of microorganisms throughout the water column by several orders of magnitude [30]. A large portion of the labile sediments from each productive cycle will be released to the environment during the exchange of water discharge and after pond harvest [31; 32]. Thus, the effects of water discharge, along with the loss of mangroves, becomes the main eco-hydrological impact on the site of an operating shrimp farm [33]. Several studies report changes to sectors associated with shrimp effluents in the composition and content of organic matter and nutrients in the receiving water bodies [34; 35; 36; 37; 38]. Additionally, a decrease in dissolved oxygen concentration [39; 40], and an increase in trace compounds have also been reported [41; 42; 43; 44]. These effects extend to sediments associated with shrimp effluents in concern with the level oforganic compounds [45; 46; 47; 48; 49; 50] and the content of metalloids [51; 52; 53], which influence the assembly of benthic organisms [54; 55]. Knowledge of the impacts of aquaculture facilities on mangroves led to a global ban on aquaculture farm facilities in mangroves and coastal wetlands. It also led to the requirement in certain countries to implement crop water treatment systems prior to discharge. This measure is theoretically required in Ecuador, given that in 2021, it was the largest producer of whiteleg shrimp farmersed in brackish waters, totaling at least 2150 farms with an area of 72.598 ha located in sectors of beaches and bays [56].