La Segura Hydrographic Confederation (CHS) has launched an ambitious study to thoroughly analyze the populations de peces and the eutrophication processes in the basin's reservoirs. This is a technical and environmental undertaking that seeks to refine existing knowledge and lay the groundwork for more effective management of these bodies of water, which are under considerable pressure from water scarcity and intensive use.
This project, included in the measure 1136 of the Hydrological Plan of the Segura DemarcationThe study will focus on assessing how fish communities relate to the ecological and trophic state of reservoirs, and on defining specific measures to prevent mortality episodes. de peces and expansion of alien speciesAll of this with an applied approach, geared towards future decision-making.
Tender, budget and deadlines for the study
The Segura Hydrographic Confederation (CHS) has initiated the bidding process for a service contract to carry out this specialized study. The base budget for the tender amounts to €287.044,07 (including VAT) , an amount intended to cover fieldwork, data analysis, supplementary studies, and the development of management proposals tailored to each reservoir.
The planned execution period is 24 months , meaning the work will extend over two full years, allowing for the collection of data during different hydrological periods and environmental conditions. According to the announcement published in the Official State Gazette (BOE), the contract is part of the actions programmed in the Segura River Basin Management Plan , thus reinforcing its alignment with official hydrological planning.
This study is not limited to a mere collection of data; the intention of the CHS is to have a solid scientific basis to define specific actions in each reservoir, taking into account its particular situation, its operating regime and the specific problems of water quality and fish fauna that are detected.
The tender also includes the obligation to integrate the results into the monitoring systems already used by the Water Commission, so that the new information is incorporated into the existing indicators on ecological and trophic status.
Objectives: fish, eutrophication and ecological status
The central objective of the contract is improve knowledge about populations de peces present in the reservoirs of the Segura River basin and their link to eutrophication processes. This involves analyzing both the species composition and their abundance and biomass, as well as their relationship with the nutrient level, water transparency and other quality parameters.
One of the key aspects of the project is to assess how the presence of certain species, especially the alien or invasive speciesIt can influence the trophic dynamics of reservoirs and the occurrence of episodes of water quality deterioration, such as algal blooms or a decrease in dissolved oxygen that end in mass mortality. de peces.
The CHS intends, with the results of the study, to have specific diagnoses for each reservoirso that they can be raised preventive measures against possible ecological crisesincluding rapid action in case of risk of mortality de peces or a sudden deterioration in water quality.
Furthermore, the project will allow for linking the status of fish populations with the ecological and trophic state of water bodies , as required by European water regulations. This will help refine the classification of reservoirs and assess whether the established environmental objectives are being met.
Working methods and sampling techniques
To carry out this analysis, the study will combine different sampling and evaluation techniquesOne of the central tools will be the hydroacousticswhich allows estimating presence and biomass de peces inside the reservoirs using acoustic signals, without needing to capture all the specimens.
Alongside hydroacoustics, direct sampling will be used with nets and electrofishing systems from boats. These methods allow for more precise identification of the species present, determination of sizes and weights, and the collection of samples for more detailed analysis, which is essential for evaluating the structure of fish communities.
The contract also includes the calculation of the Minimum Environmental Volume (MEV) in the reservoirs under study. This parameter serves to assess the risks associated with very low levels of water reserves, a particularly relevant situation in a basin as prone to drought as the Segura, where sharp decreases in stored volume can critically affect the available habitat for fish.
In the reservoirs selected for more detailed analysis, additional work is planned, including high-resolution bathymetry , substrate mapping, characterization of fine sediments, and, where appropriate, specific studies of submerged macrophytes and the structure of the food web. All of this will allow for a highly accurate picture of the physical and biological conditions of each system.
Reservoirs involved and in-depth analysis
The initial list of infrastructures to be taken into account includes a wide range of reservoirs in the Segura basin, including Cenajo, La Pedrera, Fuensanta, Puentes, Santomera, Talave, Camarillas, Alfonso XIII, Algeciras, Valdeinfierno, La Cierva, JudÃo, Anchuricas-Miller, Crevillente, Ojós, Argos and Taibilla , among others.
Within this context, the La Pedrera reservoir is of particular interest as it is the only one located in the Vega Baja region, an area with significant agricultural activity and a high dependence on regulated water resources. The information obtained from this reservoir will be key to understanding how upstream pressures influence this especially sensitive area.
Of the reservoirs considered, eight will ultimately be selected for further analysis . Among these, four will undergo an expanded study that will include detailed bathymetry, substrate mapping, in-depth analysis of fine sediments, and, where necessary, an assessment of submerged macrophytes and the food web, from primary producers to predatory fish.
This phased approach will allow resources to be prioritized in those reservoirs where they are detected increased risks of eutrophication or significant problems with populations de peceswhether due to an abundance of invasive species, previous mortality episodes, or special pressure on the resource.
Management of alien species and prevention of mortality
A particularly sensitive aspect of the study is the treatment of non-native or invasive species , whose presence in numerous reservoirs in the Segura River basin is well known. The contract stipulates that, based on the results, action plans may be proposed, including the possible elimination or control of these species when deemed necessary to protect the ecological balance.
At the same time, the project aims to establish preventive measures against mortality episodes de pecesThese are often linked to situations of extreme environmental stress, such as high temperatures, low water levels, or dissolved oxygen deficits. Having up-to-date data on biomass, species distribution, and physicochemical conditions will facilitate a faster and more accurate response if they are detected. episodes of mortality de peces.
These management proposals must be tailored to the characteristics of each reservoir, combining actions regarding fish populations with other possible measures related to operating regulations, minimum operating levels, or improved water quality monitoring. The key will be integrating biological and hydrological information to reduce the likelihood of environmental crises.
In any case, decisions regarding the control of non-native species or direct actions on populations de peces They will be adopted within the framework of the competence of the CHS and the Water Commission, taking into account the current regulations on biodiversity and conservation.
Institutional framework and functions of the CHS
The implementation of this study falls squarely within the functions of the Segura River Basin Authority regarding the administration and control of public water resources. Its responsibilities include the analysis and monitoring of inland water quality, as well as the tracking of the ecological and trophic status of the reservoirs within its jurisdiction.
The Segura Hydrographic Confederation's Water Commission , the body responsible for monitoring and controlling water quality, will play a key role in overseeing the work and integrating the results of this contract into existing hydrological and environmental information systems. In this way, the data obtained will not be isolated but will be added to the set of indicators that serve as the basis for basin management.
Within the framework of European water regulations, this type of study is essential to determine whether regulated water bodies achieve the required good ecological status . Information on fish stocks, eutrophication, and minimum environmental volume contributes to a more comprehensive understanding of the reservoirs' condition and helps justify, where necessary, the need for additional restoration or protection measures.
Overall, the tendering of this study represents a further step in the commitment to a management based on scientific knowledge in the Segura River basin. Through a combination of advanced sampling techniques, detailed analyses, and specific action proposals, the Segura Hydrographic Confederation (CHS) seeks to have more refined tools to improve the condition of reservoirs and reduce the risks associated with eutrophication and imbalances in populations. de peces.
