A system of environmentally important decision-making for the sustainable use of marine estuaries in the conditions of anthropogenic and climatic changes

Sustainable use of marine water areas is one of the priorities of preserving biodiversity and the environment as a whole. The problem of a clear plan of rehabilitation measures, which would be based on complex and balanced solutions arises for their effective restoration and further functioning. These decisions should take both environmental and economic aspects into account. Estuaries, unlike marine water areas, are more sensitive to anthropogenic and climatic changes. They are characterized by shallow water level, functioning in the conditions of limited water exchange, dependence on river flow and greater anthropogenic load compared to marine water areas. These features are the cause of more intensive changes in the structure of biocenoses, rise in emergency situations, loss of productivity and sustainability of ecosystems as a whole. Thus, there is a need to introduce environmental management for these reservoirs, which should be based on a multi-component decision support system. This system will make it possible to develop clear plans for the restoration of marine ecosystems and prevent negative changes and degradation in them. The proposed scheme for developing plans for the restoration of the ecosystems of estuaries is represented by three blocks. The first “Block of data collection” involves the implementation of 3 stages: assessment of the current state of the reservoir; definition of problems and their ranking; assessment of ecosystem services. The second block “Search for a solution” is based on 4 components: Component 1. Database management system; Component 2. Geoinformational system; Component 3. Mathematical and predictive models; Component 4. Informational and management system for choosing strategic and operational decisions. The third block “Implementation of measures” involves the implementation of 4 stages: environmental assessment of decisions and projects, implementation of environmental measures, evaluation of effectiveness, search for new solutions and their improvement. The proposed scheme will enable a comprehensive approach to the restoration of estuarine ecosystems and ensure their sustainable use.


Introduction
The United Nations has declared 2021-2030 as the International Decade on Ecosystem Restoration.The goal of this decade is to bring together all interested parties to prevent, halt and reverse the degradation of ecosystems on every continent and in every ocean.This initiative provides many areas of work that will draw attention to the problems of restoring ecosystems and ensure their sustainable use in the future [1].
The experience of European countries in the management of ecotones, lagoons and estuaries is quite broad and has several main directions.All of them are based on the basic principles of the role of water bodies as ecosystems that provide many ecological, cultural and economic benefits and advantages for people.
Most approaches to the estuary management are based on the implementation of clear measures to optimize the hydrological regime, reduce the anthropogenic load, protect certain biotopes or species, educational measures, etc. [2][3][4][5][6].
In general, most countries are trying to systematically solve the problems of managing coastal and marine ecosystems both at the legislative level and at the sectoral level (fisheries, recreation, nature protection).This approach involves giving a certain status to the water body and subsequently developing a clear management plan that depends on the specifics of the ecosystem use.
Unfortunately, in Ukraine, approaches to the systematic management of the water bodies are not carried out.Plans for the management of individual river basins are only partially implemented [7][8][9].This work is carried out within the framework of the implementation of the approaches of the EU Water Framework Directive implemented by Ukraine.For estuaries, separate attempts to develop management plans were carried out exclusively within the framework of management plan development for wetlands of international importance or touched on the management of hydrological or hydrochemical regimes [10].
Unfortunately, marine ecosystems, especially the coastal ones, have been significantly transformed over the past 50-60 years due to pollution, construction of industrial facilities, intensive development of recreation, et cetera.The speed of negative developments was intensified by the impact of threatening climate changes, which have also intensified in recent years.Estuaries are especially sensitive in this context since they, unlike marine water areas, are shallower, function with limited water exchange, depend on river flow and are characterized by a greater anthropogenic load.
From a scientific point of view, these water bodies are important for the possibility of control and implementation of various management measures to regulate and restore hydrological, hydrochemical and hydrobiological regimes.The possibility of introducing active measures aimed at stabilizing and improving ecological processes is an important condition for restoring transformed ecosystems to their natural state [11] .
For a long time, the management of these water bodies took place spontaneously and was aimed at the formation of various ecological states.Most of the feasible anthropogenic transformations have changed the course of natural processes in these ecosystems.Some ecosystems were radically transformed, isolated from sea waters, changed both at the level of abiotic characteristics and at biocenosis level [12][13][14][15][16].
That is why we propose a systematic approach to the environmental management process, the main element of which should be a multi-component decision support system.This scheme will enable to develop clear plans for the restoration and sustainable use of marine ecosystems, as well as to prevent negative changes and degradation of marine water areas.

Results and discussion
Despite the obvious need to develop a systematic approach to decision support in estuary management, there are currently no complete step-by-step schemes that allow for a comprehensive solution to the tasks of ecological management.The main defects and problems of modern ecological solutions implemented in Ukraine are: • lack of systematic scientific studies of the state of water bodies, which should be implemented on the basis of the basin approach and the requirements of the Water Framework Directive; • lack of works on the assessment of ecosystem services as a tool for understanding the ecological, social and resource value of water areas; • insufficient use of elements of the mathematical modelling of hydroecological and socioeconomic processes; • lack of understanding of the need to involve experts of appropriate qualifications by the customers and their reluctance to finance the full scope of the development at the design stage; Taking the lack of systemic solutions in the management of estuaries into account, there is a need to develop a complete step-by-step scheme that will allow to comprehensively solve the problems of ecological management.Water body management has long gone beyond purely ecological problems and today should be based on a combination of not only ecological indicators and criteria, but also include social, economic, political and legal instruments.In general, the functioning of this scheme should be based on a number of principles: • The principle of a holistic approach towards assessing the state of aquatic ecosystems.It involves a comprehensive assessment of the body of water and the factors affecting it.It is important to analyse all key factors that determine the ecological state of the body of water, and not the individual components.• The principle of the basin approach.The approach assumes that the drainage basin together with the body of water forms a single geoecosystem with transit and accumulative functions and directly affects the formation of the ecological status-class of hydroecosystems.• The principle of sustainable development.Sustainable development is considered as a compromise between economic, environmental and social spheres.The concept of sustainable development is based on three main principles [14]: ensuring a balanced economy and ecology; ensuring the balance of the economic and social spheres in the human dimension, which means the maximum use of the resources provided by economic development in the interests of the population; solving tasks related to development not only in the interests of the current generation, but also of all subsequent generations that have equal rights to resources.
The proposed scheme has three blocks: a data collection block, solution search block, and a measure implementation block (figure 1).These blocks are sequential and must be implemented in stages.At the same time, there are cases when it is necessary to give prospective assessments to qualitatively new processes and phenomena that have not been encountered before and about which, of course, there is no information.The possibility of solving the mentioned problems, even in the absence of theoretical justifications, is achieved due to the skilful use of experience, intuition and knowledge of specialists, scientists working on solving the relevant problems.This method is called the method of expert evaluations [16].It allows to rank ecological problems and to determine environmental management priorities.According to the results of this stage, priority problems will be determined, the solution of which will have the greatest cumulative effect.Stage 3. Evaluation of ecosystem services.Ecosystem services are all the benefits that humanity receives from ecosystems.In other words, these are services for providing humanity with natural resources, a healthy habitat, and other ecologically and economically significant "products".Among the numerous ecosystem services, those that provide resources (food, water, forest, raw materials), regulate processes in ecosystems (impact on the climate, control over floods, natural disasters, quality of water resources, etc.), provide cultural and social services (aesthetic and spiritual values of nature) and support the functioning of ecosystems (soil formation, photosynthesis, nitrogen cycle, etc.) can be selected.Unfortunately, the modern paradigm of environmental management does not take this assessment into account and, accordingly, the adoption of an ecologically important decision is evaluated unilaterally and does not take all aspects of the use of the estuary ecosystem into account.Today, there are various approaches to the assessment of ecosystem services.Thus, the Ramsar Committee, within the framework of wetland management, proposed a rapid assessment of ecosystem services (Resolution XIII.17).RAWES (Rapid Assessment of Wetland Ecosystem Services) practical approach was designed as a simple and rapid assessment system that draws on data from existing research but does not include detailed quantitative assessment.For a more efficient and quantitative assessment of ecosystem services, a cost evaluation should be used [17,18].
The second block of the systemic decision-making scheme for estuary management is based on the implementation of the decision support system.The essence of the management process is to make a decision -it is the choice of a course of action from a set of existing alternative options.In such conditions, the problem of choosing the most rational and effective solutions, that is, the best solutions, becomes one of the most important tasks of production management [16].
This system is designed to support various types of activities when making decisions on sustainable estuary use, restoration and management of the ecological state of the marine environment with achieving socio-ecological and economic profit.The application of the system ensures a thorough and objective analysis of the subject area when making decisions in difficult conditions.In modern conditions, this approach helps to make management decisions, taking more than one environmental factor into account and makes it possible to assess the short-and long-term effects of the implementation of management measures.The multi-vector and holistic approach of this information technology allows state management bodies, private investment institutions, and local communities to decide on the most appropriate scenario for managing local marine ecosystem in order to obtain the best socio-ecological and economic effect.
This system is based on 4 components: Component 1. Database management system.Provides the ability to accumulate and process primary data.It includes the following databases: climatic, hydrometeorological, water quality, diversity of flora and fauna, natural resources and their use, recreational resources and their use.Component 2. Geoinformational system.Allows to visualize the decision-making process and demonstrate the scale of changes or potential consequences from the implementation of management decisions.Component 3. Mathematical and predictive models.This component is based on the broad involvement of mathematical modelling of all processes that are observed during the interaction of living beings with each other and the environment under the conditions of intense anthropogenic load.Component 4. Informational and management system for choosing strategic and operational decisions.Provides an opportunity to predict possible changes in the ecosystems based on database analysis using hydrological and climate models.This, in turn, allows to form possible scenarios of ecosystem development.
With the use of dynamic flow charts, it will be possible to choose a strategic and operational decision or a specific management measure, which will be aimed at overcoming environmental and socio-economic risks.
The third block of the systemic decision-making scheme for estuary management is dedicated to the implementation of the decisions made and includes 4 stages.
Stage 1. Environmental assessment of decisions and projects.This stage involves the completion of legally regulated evaluation processes of planned measures.Depending on the type of activity, Strategic Environmental Assessment and Environmental Impact Assessment are distinguished.Strategic Environmental Assessment (SEA) is a procedure that is necessary in order to determine, describe and evaluate the consequences affecting the environment and the health of the population through the implementation of state planning documents (urban planning documentation: a master plan, a detailed plan of the territory or a territory zoning plan, schemes of district planning, strategies, national programs, state target programs and other programs and program documents that are developed and/or subject to approval by the state authority, local self-government body), development of measures to prevent, reduce and mitigate possible negative consequences [19].The Environmental Impact Assessment procedure (EIA) is designed to identify the nature, intensity and degree of danger of the impact of any type of planned economic activity on the state of the environment and the health of the population [20].Stage 2. Implementation of environmental measures.As part of this stage, the planned activities for solving environmental problems of a specific body of water are being implemented.It should be noted that expert supervision of measure implementation and ecological and economic audits are integral tools within this stage.Quite often, non-compliance with technological processes or changes in design solutions occur during the implementation of measures.Stage 3. Efficiency evaluation.The effectiveness measure implementation of measures is the final condition of ecological management.Thus, estuary management aims to solve not only environmental problems, but also take social and economic aspects into account.That is why efficiency evaluation should be based on the assessment of the state of indicator species and habitats, as well as on socio-economic indicators in the region of implementation of ecological management projects.Stage 4. Search for new solutions and their improvement.The cyclic nature of ecological management is an important component of the continuous development and preservation of the natural resource potential of estuaries.Given that the estuaries of the region are complex natural multicomponent systems, changes in which can occur quite rapidly, it is necessary to include constant improvement of control elements.It is also important to note that our knowledge and management methods are constantly improving, and this, in turn, can contribute to the search for more effective measures to restore these hydroecosystems.

Conclusions
The Azov-Black Sea coast is represented by a significant number of estuaries and bays, which functioned for a long time thanks to an artificial connection with the sea.Molochny, Berezansky, Tyligulsky, Tuzlovsky estuaries, Eastern Sivash, and others are among them.They have important scientific, social and environmental significance.Most of them are included in the nature protection territories of Ukraine as national parks and have the status of wetlands of international importance.On the other hand, they are important from the socio-economic point of view, since reproduction and feeding of fish takes place in their water areas, and in the future, fishery.
The functioning of most estuaries in the region has always been related to the level of water exchange through artificial channels with Azov or Black Sea.For a long time, the management of these bodies of water took place spontaneously and was aimed at the formation of various ecological states.The lack of a systemic concept in the development of estuary management IOP Publishing doi:10.1088/1755-1315/1254/1/0120187 plans does not make it possible to make the necessary management decision.An important element in choosing the necessary solutions is the evaluation of ecosystemic services, as a tool for finding a balance between ecological, social and economic directions of estuary use.These assessments should determine the development vector of the estuary ecosystem, which will ensure the rational use of its natural resource potential.
Despite the obvious need to introduce a systemic approach to decision-making for estuary management, there are currently no methods of holistic assessment of their condition and decision-making strategies within the framework of ecological management.The proposed comprehensive approach is a practical tool for ensuring balanced nature management of the investigated hydroecosystems.Developed scheme of stages of systemic decision-making for estuary management is based on the implementation of successive stages, with a multicomponent decision support system functioning in its centre.This scheme is cyclical and requires constant improvement of the decisions made and evaluations of the effectiveness of measures.

Figure 1 .
Figure 1.Scheme of the stages of making systemic decisions on estuary management Stage 1. Assessment of the current state of the body of water.This stage is associated with the need to conduct complex hydroecological studies.It is important to note that in Ukraine on September 19, 2020, the Resolution of the Cabinet of Ministers of Ukraine approved the Procedure for State Water Monitoring.State water monitoring is carried out in order to ensure the collection, processing, preservation, generalization and analysis of information about the state of the bodies of water, forecasting its changes and developing scientifically based recommendations for decision support in the field of water use, protection and reproduction of water resources.It is important to note that this monitoring is based on the basin principle and is regulated by the EU Water Framework Directive.Today, unfortunately, the water monitoring system is not fully implemented.Modern works performed by authorized bodies relate to [15]formation of reference indicators.At the same time, the assessment is based on the comparison of the current values of hydrobiological, physicochemical and hydromorphological indicators, determined in the monitoring process, with their reference values, that is, those that could exist in the absence of anthropogenic influence[15]. 4