Guayas River Basin

​Health risk-benefit assessment of the commercial red mangrove crab: Implications for a cultural delicacy
March 2023
Mangrove forests, provide vital food resources and are an endangered ecosystem worldwide due to pollution and habitat destruction. A risk-benefit assessment (RBA) was performed on the red mangrove crab (Ucides occidentalis) from the threatened Guayas mangroves in Ecuador. It was aimed to assess the combined potential adverse and beneficial health impact associated with crab consumption and define a recommended safe intake (SI) to improve the diet of the Ecuadoran population while ensuring safe food intake. In conclusion, the red mangrove crab contains various important nutrients and can be part of a balanced diet for the Ecuadorian population when consumed in limited portions. The present study emphasizes the importance of safeguarding the quality of the environment as a prerequisite for procuring nutritious and safe food.

The nutritional quality of the red mangrove crab (Ucides occidentalis), harvested at two reserves in the Guayas estuary
February 2023
Crabs are an outstanding source of many essential nutrients. Little research has been performed on the nutritional quality of the red mangrove crab (Ucides occidentalis). In this research we investigated the proximate composition, fatty acid profile, amino acid composition, and mineral concentrations of red mangrove crabs sampled at two reserves within the Guayas estuary in Ecuador. We found that the red mangrove is a good source of nutrition for a balanced diet and can contribute to the recommended intake of essential nutrients. Current research indicated that the final nutritional quality indices of the red crab were not influenced by harvest site. More research into the influence of environmental and ecological factors on the nutritional composition of crabs is suggested.

Bayesian belief networks for the analysis of the controversial role of hydropower development in the antagonistic agrofood-fisheries nexus: A potential approach supporting sustainable development in the Guayas river basin (Ecuador)
November 2022
Increasing anthropogenic activities are affecting water quality and related ecosystem services in river basins worldwide. There is a need to identify and act on synergies between the water-energy-food (WEF) elements and the other Sustainable Development Goals (SDGs) while mediating trade-offs. The Guayas river basin (GRB), one of the major watersheds in Ecuador, is being affected by increasing urbanization, agricultural and industrial activities. In this perspective paper, we indicate the WEF interactions in the GRB linked to the SDGs. A Bayesian belief network (BBN) framework was developed in order to support sustainable decision making in the GRB. The discussed concepts can be applied to other river basins worldwide since, in many basins, very similar food production challenges need to be addressed.

From field to plate: Agricultural pesticide presence in the guayas estuary (Ecuador) and commercial mangrove crabs. 
November 2021
A multi-residue analysis involving a selection of 88 pesticides was performed on the white meat and the hepatopancreas of the red mangrove crab (Ucides Occidentalis) at 15 sampling sites within the Guayas estuary along with water, sediment, and leaves samples. An ecotoxicological and probabilistic consumer risk assessment pointed out that current butachlor, carbendazim, and fludioxonil concentrations can cause adverse effects in aquatic organisms in the long term. Moreover, high potential acute and chronic risks of cadusafos residues on aquatic invertebrates and of diuron on algae in the Guayas wetlands were observed. Still, the exposure results indicated that the health risk for the consumers of the commercial red mangrove crab is low concerning cadusafos, chlorpyrifos, diuron, linuron, and pyrimethanil residues in crab tissues. The findings presented in this research can provide a useful basis for local water managers and environmental conservation groups to act and reduce the usage of pesticides, to avoid threatening aquatic and human health.

From Mangrove to Fork: Metal Presence in the Guayas Estuary (Ecuador) and Commercial Mangrove Crabs​
August 2021
Metal pollution due to industrial and agricultural activities represents an issue of growing concern for the Guayas River Basin and related mangroves in Ecuador. In order to protect human health and aid river management, we analyzed several elements in the Guayas Estuary. Zn, Cu, Ni, Cr, As, Pb, Cd, and Hg accumulation were assessed in different compartments of the commercial red mangrove crab Ucides occidentalis (hepatopancreas, carapax, and white meat) and the environment (sediment, leaves, and water), sampled at fifteen sites over five stations. Consistent spatial distribution of metals in the Guayas estuary was found. Nickel levels in the sediment warn for ecological caution. The presence of As in the crabs generated potential concerns on the consumers’ health, and a maximum intake of eight crabs per month for adults is advised. The research outcomes are of global importance for at least nine Sustainable Development Goals (SDGs). 

Bayesian Belief Network models as trade-off tools of ecosystem services in the Guayas River Basin in Ecuador
August 2020
Food production often leads to environmental degradation. Consequently, insights into ecosystem functioning in relation to exploitation are needed as a basis for socioeconomically acceptable mitigation of these impacts. In this study, a Bayesian Belief Network (BBN) model is developed to link three major ecosystem services (ES), i.e. food production, water provision and ecotourism, and determine the effect of local agricultural practices and management on the ES in the Guayas Basin (Ecuador). The BBN development approach can serve as a reference for other case studies, where data scarcity plays a limiting factor in the assessment of interactions between key ES.

Using the Soil and Water Assessment Tool to Simulate the Pesticide Dynamics in the Data Scarce Guayas River Basin, Ecuador
March 2020
Agricultural intensification has stimulated the economy in the Guayas River basin in Ecuador, but also affected several ecosystems. The increased use of pesticides poses a serious threat to the freshwater ecosystem, which urgently calls for an improved knowledge about the impact of pesticide practices in this study area. This study tested the suitability of the Soil and Water Assessment Tool (SWAT) to simulate the dynamics of two different pesticides in the data scarce Guayas River basin. This study showed that SWAT has been evaluated to be a suitable tool to investigate the impact of pesticide use under data scarcity in the Guayas River basin. The results can also be helpful to design future water quality monitoring strategies. Provided that key suggestions for further improvement are considered, the model is valuable for applications in river ecosystem management of the Guayas River basin.

Distribution of agricultural pesticides in the freshwater environment of the Guayas river basin (Ecuador)
January 2019
The rapid increase and transition to more intensive agricultural activities in developing nations are often leading to misuse and overuse of pesticides, making their environment vulnerable for pesticide accumulation. In the present study, the Guayas river basin was taken as a representative case study to evaluate pesticide contamination of the Ecuadorean freshwater environment. Results showed that pesticide contamination of the freshwater environment was widely present in the Guayas river basin with detections at 108 sampling sites (60). These pesticide residues were associated with one or more agricultural crops, with in particular the banana and rice industries identified as major pollution sources. It is suggested that measures, e.g. legal regulations and awareness campaigns, taken to prevent environmental pollution and accumulation of pesticides primarily focus on these industries.

Threshold Responses of Macroinvertebrate Communities to Stream Velocity in Relation to Hydropower Dam: A Case Study from The Guayas River Basin (Ecuador)
​September 2018
The Guayas River basin is one of the most important water resources in Ecuador, but the expansion of human activities has led to a degraded water quality. The purpose of this study was (1) to explore the importance of physical-chemical variables in structuring the macroinvertebrate communities and (2) to determine if the thresholds in stream velocity related to macroinvertebrate community composition could be identified in the Guayas River basin. The results provide essential information to define environmental flows to further support water management plans of the Guayas River basin. 

Impact assessment of local land use on ecological water quality of the Guayas river basin (Ecuador)
November 2018
In this study, the effect of land use on the ecological water quality both within direct vicinity and within a distance of 200 m from the sampling sites was invstigated. Models involving land use assessed using aerial pictures, field protocols and GIS data were associated mainly with hydromorphological variables. However, the models incorporating land use evaluated on a larger spatial scale (i.e. Google maps and GIS maps) were also associated with physical-chemical variables. Although, the land use assessment based on aerial pictures using Google maps” had the best outcome, a combined approach using field observation and aerial pictures can provide comprehensive land use data to the water management and provides the most complete information to define local land use of the sampling sites.

Input variable selection with a simple genetic algorithm for conceptual species distribution models: A case study of river pollution in Ecuador
June 2017
Species distribution models (SDMs) have received increasing attention in freshwater management to support decision making. This paper presents a methodology, illustrated with the example of river pollution in Ecuador, using a simple genetic algorithm (SGA) to identify well performing SDMs by means of an input variable selection (IVS). An analysis for 14 macroinvertebrate taxa shows that the SGA is able to identify well performing SDMs. However, it is observed that uncertainty on the model structure is relatively large. To conclude, the developed tool can aid model developers and decision makers to obtain insights in driving factors shaping the species assemblage.

Fuzzy modelling to identify key drivers of ecological water quality to support decision and policy making
February 2017
Water quality modelling is an effective tool to investigate, describe and predict the ecological state of an aquatic ecosystem. Appropriate selection of a limited number of key-variables facilitates cost-effective management of water resources. This paper aims to determine (and analyse the effect of) the major environmental variables predicting ecological water quality through the application of fuzzy models. In this study, a fuzzy logic methodology, previously applied to predict species distributions, was extended to model environmental effects on a whole community. The model outcome can support spatial planning related to land use in river basins and policy making related to flows and water quality standards. 

Generalized Linear Models to Identify Key Hydromorphological and Chemical Variables Determining the Occurrence of Macroinvertebrates in the Guayas River Basin (Ecuador)
July 2016
The biotic integrity of the Guayas River basin in Ecuador is at environmental risk due to extensive anthropogenic activities. In this study the potential impacts of hydromorphological and chemical variables on biotic integrity using macroinvertebrate-based bioassessments was investigated. Although the results of the models provided insights into the ecosystem, cross fold model development and validation also showed that there was a level of uncertainty in the outcomes. To conclude, the results of the models and sensitivity analysis can support water management actions to determine and focus on alterable variables, such as the land use at different elevations, monitoring of nitrate and chlorophyll concentrations, macrophyte presence, sediment transport and bank stability. 

Ecological water quality analysis of the Guayas river basin (Ecuador) based on macroinvertebrates indices
March 2016
The Guayas river basin is one of the major watersheds in Ecuador, where increasing human activities are affecting water quality and related ecosystem services. The aims of this study were (1) to assess the ecological water quality based on macroinvertebrate indices and (2) to determine the major environmental variables affecting these macroinvertebrate indices. Two biotic indices were calculated to assess the water quality with an ecological approach: the Biological Monitoring Working Party Colombia (BMWP-Col) and the Neotropical Low-land Stream Multimetric Index (NLSMI). Both the BMWP-Col and NLSMI indicated good water quality at the (upstream) forested locations, lower water quality for sites situated at arable land and bad water quality at residential areas. To conclude, the applied methods and results of this study can be used to support the future water management of the Guayas river basin and similar basins situated in the tropics.

Bayesian belief network models to analyse and predict ecological water quality in rivers
September 2015
Economic growth is often based on the intensification of crop production, energy consumption and urbanization. In many cases, this leads to the degradation of aquatic ecosystems. Modelling water resources and the related identification of key drivers of change are essential to improve and protect water quality in river basins. This study evaluates the potential of Bayesian belief network models to predict the ecological water quality in a typical multifunctional and tropical river basin. Model predictions and sensitivity analysis indicated that flow velocity is the major variable determining ecological water quality and suggested that construction of additional dams and water abstraction within the basin would have an adverse effect on water quality. Although a case study in a single river basin is presented, the modelling approach can be of general use on any other river basin.