Management Strategies to Mitigate Anthropogenic Impacts in Estuarine and Coastal Marine Environments: A Review

A wide range of anthropogenic activities impacts estuarine and coastal marine environments including interactive climate and non-climatic drivers of change that can significantly degrade biotic communities and habitats. Many of these environments are in decline due to changes in ecosystem structure and function resulting from multiple stressor effects. In addition, inadequate governance has supported a patchwork of single issues or sectoral approaches rather than integrated management of multiple human uses and activities to maintain healthy, productive, resilient, and sustainable ecosystems and the provision of goods and services. Ecosystem-based marine spatial planning is a viable framework for a more effective governance structure and management of these vital coastal environments. An important component of this approach is a holistic effort to assess the environmental, economic, and societal impacts of anthropogenic activities. Thus, a multidisciplinary integrated approach is preferred that links ecological, physical, and socio-economic systems, increasing the protection of resources and societal benefits. For degraded estuarine and coastal marine ecosystems, restoration and rehabilitation initiatives are important intervention strategies used to reverse the loss of habitats and biotic resources and to support management programs. Marine Protected Areas (MPAs) are an integral element of marine management plans to conserve and sustain estuarine and coastal marine environments by protecting threatened ecosystems and their resources from anthropogenic activities. National and international regulatory frameworks and directives are also in place to protect and conserve these environments.


Introduction
Estuaries and coastal marine waters are among the most productive environments in the world. Yet, they are often the most heavily impacted by anthropogenic activities. Despite their susceptibility to anthropogenic degradation, these environments support numerous species of organisms and habitats of ecological importance, while also providing vital goods and services to society. Estuaries alone cover more than 400,000 km of the global coastline with an estimated surface area of 1.1 × 10 6 km 2 [1] [2]. They form transitional environments between terrestrials, rivers, and open ocean systems and thus are vulnerable to an array of anthropogenic impacts because coastal lands nearby are often highly developed and densely populated, with human activities greatly affecting ecosystems along the watershed, river, estuary, and coastal ocean continuum [3] [4]. The protection and maintenance of estuarine and coastal marine environments require integrated ecosystem management that considers the connectivity of land, estuary, and ocean components [5].
Four classes of anthropogenic drivers are potentially threatening estuarine and coastal marine environments, notably industrialization and urbanization, habitat degradation, increasing use of resources and space, and climate change [2] [6] [7]. They are particularly problematic when acting synergistically with other drivers of change to impact the structure and functioning of these environments and to reduce ecosystem goods and services. The net effect is decreasing resistance and resilience of ecosystems, as well as a reduction of their sustainable use due to climate change and non-climatic anthropogenic factors [7].
This article reviews the management strategies and legislative frameworks that address anthropogenic drivers of change and impacts in estuarine and coastal marine environments and which serve as vehicles for ecosystem protection and conservation. Day et al. [8] convey that most, if not all, coastal systems have serious environmental problems due to multiple stressors that require management intervention. Although no general administrative plan targets and successfully remediates all problems existing in estuarine and coastal marine environments, management measures exist to mitigate serious impacts in an effort to promote and sustain healthy ecosystems.
The main objective of the article is to synthesize the aforementioned management strategies and legislative frameworks, examining other published works on the subject such as the comprehensive treatments of Elliott [5], Kennish and Elliott [6], Defeo and Elliott [7], and others. To this end, the general structure of the article consists of several key components that follow: types of anthropogenic impacts, management strategies, management frameworks, remediating damaged coastal environments, and regulatory frameworks. As noted by Elliott et al. [5], the degradation of biotic communities and habitats in natural systems due to  [14]. Warming waters in estuaries account for observed poleward range shifts of organisms from estuary to estuary [15]. Other biotic responses to climate change projected in many estua-Open Journal of Ecology rine waterbodies include an increase in invasive species, harmful algal blooms (HABs), and pathogens [4].

Management Strategies
A primary goal of estuarine and coastal marine ecosystem management is to protect biotic communities and habitats from adverse effects of human activities and natural events, including changes that pose a threat to ecosystem structure, functioning, and sustainability [5] [10] [16]. As such, it is not only important to examine the structure of an ecosystem (i.e. species richness, abundance, biomass, density, etc.) but also its functioning (i.e. rate processes) and the effects of activities on human uses of estuarine and marine waters. In addition, it is necessary to assess and maintain the natural hydrodynamics, sedimentology, geomorphology and other characteristics of an ecosystem.
Ecohydrology and ecoengineering are important tools used in estuarine management to address altered or damaged habitats and biotic communities and to improve ecosystem conditions. Restoration and rehabilitation are also vital in returning impacted ecosystems to an improved condition. Successful estuarine restoration projects require both effective science and societal components. In fact, development and implementation of ecological restoration projects are processes involving the interaction of multiple actors. Such projects are successful when they lead to the recovery and increased resiliency of degraded ecosystems [17].

Ecosystem-Based Management
An objective of estuarine and marine environmental management is also to ensure the maintenance of ecosystem goods and services beneficial to society [18] [19]. An ecosystem-based management approach is a holistic strategy that considers the entire ecosystem, including human activities and other societal components [5] [20] [21] [22]. It examines an array of interactions occurring in an ecosystem rather than focusing on a single element (e.g. species, microbes, or ecosystem services). As defined by the Secretariat of the Convention on Biological Diversity [23], "The ecosystem approach is a strategy for the integrated management of land, water, and living resources that promotes conservation and sustainable use in an equitable way". The goal of this approach is to maintain the ecosystem in a healthy, productive, and resilient condition, while providing goods and services for human use and enhancing sustainability of resources [21] [22]. A focus is to balance the intensity of human activities with the ability of estuarine and marine environments to provide ecosystem services. A need exists for governance to support integrated coastal management [20].
In a systematic review of 151 peer-reviewed papers on governance and land-sea connections, Pittman and Armitage [24] found that ecosystem-based management is the main management approach used to address land-sea interactions.
Far fewer alternative management approaches are presented in the published li- The interactions between ecological structure and functioning, physico-chemical processes, and socio-economic systems account for the complexity of managing estuarine and coastal marine environments [16]. Hence, effective integrated ecosystem management of these environments should consider the application of a holistic problem-structuring framework such as a Drivers-Activities-Pressures-State Change-Impacts-Responses approach. This linked framework approach is an effective and accurate way to assess the causes, consequences, and responses of change in natural coastal ecosystems affected by anthropogenic activities.
Also significant in this management approach is an understanding by policymakers, managers, and stakeholders of the links between environmental condition and society as well as the distribution and intensity of human activities [16] [25].
Elliott et al. [16] and Elliott [26] conveyed that underlying effective marine management is the aforementioned holistic unifying framework that constitutes a constructive integrated process designed to protect and conserve natural ecosystems. Essentially, drivers of basic human needs lead to Pressures of State changes on ecosystems causing Impacts (on human welfare) requiring Responses (as measures) to remediate. Elliott et al. [16] provide a detailed explanation of this framework, which links natural and social systems, creating an ecosystem approach for managing estuarine and marine environments to protect and maintain natural systems while supporting ecosystem services that yield societal goods and benefits [26]. This interlinked framework also reflects management of ecosystems along the watershed, river, estuary, coastal ocean continuum encompassing components of ecosystem structure and functioning, ecosystem Thus, a multidisciplinary integrated approach is preferred that links natural and social sciences and protects ecosystem services and societal benefits. The loss of ecosystem services and societal benefits due to anthropogenic pressures is a key element considered in sustainable and successful marine management programs [26] [27] [28].
Estuarine and coastal marine environments can change markedly when subjected to anthropogenic pressures. Three major sources of these pressures are recognized: 1) activities that remove materials and space from an ecosystem (e.g. fish, shellfish, and sediments); 2) activities that place materials into an ecosystem (e.g. wastewaters, toxic pollutants, and power plant thermal discharges); and 3) activities causing external and wider pressures on ecosystems (e.g. fossil-fuel burning, greenhouse gas emissions, and climate change) [3] [6] [26]. The environmental, economic, and societal impacts of all activities should be considered in an integrated analysis of these environments. The interaction of local pressures (e.g. coastal development, overfishing, nutrient enrichment) and global pressures (e.g. increasing temperatures, rising sea levels, and acidification) is deleterious to the structure and functioning of estuarine and coastal marine ecosystems. Effective ecosystem-based management must identify the influences of land-based drivers that can negatively impact and alter these ecosystems. Coastal watersheds are areas of potentially damaging anthropogenic activities that impact coastal waters, and hence proactive land-sea conservation planning and governance are vital to protecting these ecosystems together with efforts to mitigate local impacts along the land-sea continuum (Fredston-Hermann et al. 2016). For example, coastal runoff containing chemical contaminants, excess nutrients and sediments, bacterial and viral loadings, and other substances from land-based human activities can seriously impair estuarine and coastal marine waters and must be targets of management and remediation programs. An ecosystem impacted by anthropogenic pressures may be degraded, or it may exhibit resistance to change. The ecosystem may also exhibit resilience by returning to a former state after removal of the pressure [26] [27]. Elliott and Kennish [28] defined ecological resilience as the ability of an ecosystem to return to its original state after being disturbed. However, after the pressure is removed, an ecosystem may not follow a trajectory reverting back to the original environmental condition but to an alternate stable state, although shifting baselines may still yield an improved condition. Degraded or disrupted ecosystems typically exhibit lower resilience. Broad changes in environmental condition over time due to anthropogenic pressures lead to shifting baselines away from the ecosystem reference condition, imposing dynamic trajectories that limit restoration and recovery capability [29].

Ecosystem-Based Marine Spatial Planning
Ecosystem-based marine spatial planning (EB-MSP) is an effective strategy for Open Journal of Ecology supporting healthy coastal and ocean ecosystems and sustained human uses of estuarine and marine waters [30] [31]. It is a strategy implemented to manage for cumulative activities in an area rather than for sectoral applications [25]. Foley et al. ([31], p. 956) defined EB-MSB as "an integrated planning framework that informs the spatial distribution of activities in and on the ocean in order to support current and future uses of ocean ecosystems and maintain the delivery of valuable ecosystem services for future generations in a way that meets ecological, economic, and social objectives". According to Foley et al. [31], EB-MSP addresses declining health of marine ecosystems in the following ways: 1) informing the spatial distribution of activities in estuarine and marine environments; 2) maintaining human uses and reducing use conflicts in these environments; and 3) restoring, protecting, and sustaining ecosystem health and services. EB-MSB is a process based on ecological principles incorporated into a decision-making framework that leads to healthy and functioning ecosystems and services that contribute to sustainable economic and societal benefits.
Marine spatial planning has rapidly gained favor as an important aspect of integrated coastal management and sustainability of estuarine and coastal marine ecosystems and their resources in waters of the European Union [5] [21]. It is a framework to manage human activities in space and time and to achieve planning objectives that support uses of healthy marine ecosystems and maintenance of ecosystem services [20]. Factors of importance include land-sea connectivity, habitat structure, habitat heterogeneity, species diversity, and maintaining key species diversity that has disproportionately strong influence on community structure and functioning in these ecosystems [31]. planning of these waters [21]. Katsanevakis et al. [20] showed that marine spatial planning supports ecosystem-based management by considering an array of interactions that occur within an ecosystem. Many estuarine and marine governing bodies now promote EB-MSP as the best way to ensure sustainability of estuarine and marine ecosystems and their services for humans [20] [21].

Integrated Coastal Zone Management
Integrated Coastal Zone Management (ICZM) is a resource management system that uses an integrative, holistic approach and an interactive planning process to resolve complex coastal management issues [32]. Originated in 1992, ICZM has been implemented to address the coastal problems that can pose a threat to the economic sustainability and environmental quality of coastal environments. It incorporates input of governing bodies, administrators, scientists, and stakeholders to assess environmental and societal goals in a coastal area and to develop effective resolution to problems. The planning process seeks a balance of environmental, social, cultural, recreational, and economic elements affected by

Remediating Damaged Coastal Environments
Continued coastal population growth and development, increasing environmental stressors, and resulting impacts on coastal watersheds and estuaries are manifested by the changing structure and functioning of ecological communities, fragmented habitats, and reduced sustainability of ecosystems. Species abundance, distribution, and diversity in estuaries are affected by both natural and human-induced drivers of change such as increased intensity of hurricanes, nor'easters, and storm surges as well as nutrient enrichment, wastewater contaminant inputs, freshwater diversions, hardened shorelines, wetlands reclamation, fisheries overharvest, and other factors [4] [5] [9] [16] [33]. Drivers of change do not act in isolation in estuaries and coastal marine waters but are interactive, including climate change factors that can exacerbate the effects of direct, non-climatic anthropogenic factors. Multiple interactive drivers associated with anthropogenic climate change and non-climatic human pressures account for significant nonlinear effects of cumulative environmental impacts on biotic communities and ecosystem function. Driver effects can be additive, synergistic, or antagonistic, and they are often disruptive, leading to ecosystem dysfunction and depletion of resources [9]. Some estuaries exhibit insidious habitat degradation and biotic community alteration in response to some anthropogenic stressors (e.g. eutrophication), whereas others cause sudden acute changes (e.g. oil spills).
Elliott and Quintano [34] recount that estuaries are particularly difficult environments to assess human impacts because they are naturally stressed, highly variable ecosystems in nature, and hence it is often more challenging to detect anthropogenically-affected areas there than in more stable, less naturally stressed environments. Unless the action of an anthropogenic stressor is severe (e.g. sewage outfall or dredging), less acute anthropogenic impacts may go undetected in estuaries. The concept of Estuarine Quality Paradox, as related by Elliott and Quintano [34], emphasizes the difficulty of distinguishing natural from human-induced stresses in estuaries. Accurate assessment of natural and anthropogenic stresses in estuaries requires extensive data collection and analysis on the structure and functioning of biotic communities, as well as the condition of habitats [3] [4] [9] [33].
Impaired estuarine and coastal marine ecosystems often require considerable amounts of time to recover from anthropogenic and natural stressors after they are lifted. Borja et al. [35] noted that coastal ecosystems affected by anthropogenic stressors typically require up to 10 -25 years recovering from the stressor impacts. Restoration can facilitate the recovery process, although impacted ecosystems often do not return to their original state but rather to an improved pre-existing condition [36] [37].

Ecological Engineering
Mitsch [38] defined ecological engineering (also termed ecoengineering) as the design of sustainable ecosystems that integrate human society with its natural environment for the benefit of both. Ecological engineering is a vector for restoration of ecosystems altered by human activities with a goal of establishing sustainable resources having both human and ecological value and often employing ecohydrology to restore ecosystem functioning [39]. As such, ecological engineering is closely aligned with ecosystem restoration. It is a working arm of coastal marine management.
Ecological engineering is an applied approach to improve the ecology of an ecosystem through engineering of physical-chemical processes, such as water quality and quantity, or engineering of biotic components, such as replanting or restocking biota [39]. Ecological engineering often employs ecohydrology to create or re-create habitats that ecologically enhance development of natural populations, communities, and fisheries resources. They also are used for storm, flooding, and erosion protection of built communities in vulnerable coastal areas, for agriculture and lowland development, and for mitigation or elimination of pollutant loadings to coastal waterbodies. As noted by Elliott et al. ([39], p. 13), ecological engineering involves… "manipulating the estuarine or coastal system either to restore it from past degradation or to improve the delivery of nature conservation and natural structure and functioning to increase estuarine goods, services, and social benefits".

Restoration of Impacted Environments
There are long-term restoration programs in place that focus on recovery of damaged estuarine and coastal marine environments. They typically involve measures to restore ecosystem structure and functioning, although this process is generally protracted. Declining coastal ecosystems commonly exhibit an array of characteristics that warrant restoration, for example: 1) escalating habitat fragmentation; 2) reduced habitat and species diversity; 3) altered population size, dynamics, and range of species; and 4) decreased goods and services [28]. Major processes degrading estuarine and coastal marine environments typically include the introduction into or removal of physical and chemical materials, physical structures, and organisms in an area [40]. Restoration is not only limited to biotic and habitat components, but also may include the restoration of hydrodynamic and morphological characteristics. Innovative coastal marine ecosystem tools are available to reverse the decline of impacted areas.
Ecosystem restoration is an emerging field and a primary intervention strategy used to reverse the loss of estuarine and coastal marine habitats due to natural and anthropogenic pressures and to increase their resilience to climate change and other drivers of change. Abelson et al. ([41], p. 2) defined restoration simply as "the process of assisting the recovery of damaged, degraded, or destroyed ecosystems". Recovery means an ecosystem will return to a prior condition after Open Journal of Ecology being degraded or disrupted [28]. The United Nations Convention on Biological Diversity [42] has added that ecological restoration is a means of sustaining ecosystem resilience and conserving biodiversity. Coastal ecosystem restoration and rehabilitation are a means of addressing the loss of natural habitats, the consequent impacts on biotic communities, and the decreasing ecosystem services that adversely affect human uses. Elliott and Kennish ([28], p. 354) defined rehabilitation as "the act of partially or, more rarely, fully replacing structural or functional characteristics of an ecosystem that have been reduced or lost". Rehabilitation of a degraded habitat does not mean it returns to an original state. Instead, it typically refers to an improved condition of the degraded state of a habitat or ecosystem, rather than one that has returned to its original state after being degraded or disrupted.
The magnitude of habitat losses in estuaries and other coastal environments has been significant for more than a century, as exemplified by global areal losses of salt marshes, mangroves, seagrasses, kelp beds, oyster reefs, and coral reefs amounting to 35% -85% [43]. Because of the substantial goods and services these ecosystems provide, innovative conservation solutions are needed to sustain them, together with management approaches that integrate restoration targets to improve ecological conditions. Despite the ongoing loss of coastal habitat in many regions due to climate change-mediated sea level rise, surveys indicate that coastal ecosystem resilience persists in the face of climate change effects [44].
The effectiveness of coastal marine ecosystem restoration increases when incorporating socio-economic elements [41] [45]. While ecological restoration of estuaries is a governance process, socio-economic interests are often preferred over ecological interests, which can influence outcomes. Successful development and implementation of ecological restoration projects in estuaries depend on the application of workable governance conditions. Buitenhuis and Dieperink [17] state that successful restoration projects are those contributing to healthy and resilient ecosystems. They conclude that there is greater success of ecological restoration projects when three conditions are met: 1) when stakeholders provide sufficient project support; 2) when individuals in key positions provide support for the project; and 3) when undertaking research on the target area prior to the development and implementation process of the project. Saunders et al. [43] reported that restoration interventions in coastal marine environments can be successful over large spatial scales (1000s to 100,000s of hectares), while also being cost-effective and providing social and economic benefits. While restoration has proven highly effective in rehabilitating many damaged estuarine and coastal marine environments, it can be expensive to implement and complete, as evidenced by the cost of previous restoration projects in these environments. Bayraktarov et al. [46] indicated that the median costs for restoration projects are in the hundreds of thousands of dollars per hectare, although many successful scaled-back restoration projects are in the tens of thousands of dollars per hectare. Open Journal of Ecology Restoration is an integral part of conservation management that uses sciencebased techniques and methodologies to enhance the structure, functioning, and health of degraded estuarine and coastal marine ecosystems [45]. More recently, the social dimensions of ecological restoration have been incorporated as well [43]. There are many examples of restoration success in coastal ecosystems, such as the rebuilding of salt marshes, mangroves, and seagrass habitats, repopulating shellfish beds, removing contaminated bottom sediments and hardened shoreline structures, installing oyster reef substrate, enhancing coral reefs, re-establishing freshwater inflow, eliminating problematic invasive species, and improving water quality of land runoff [37], although there is much more work remaining to advance restoration practices in estuarine and coastal marine environments [41].
The use of living shorelines, artificial oyster reefs, and thin-layer sediment application on wetland surfaces is mitigating the effects of habitat loss due to sea level rise, inundation, and erosion, thereby increasing wetland resilience, sustainability, and vital ecosystem services [47] [48]. Furthermore, they can enhance sediment deposition and accretion to expand the area of the wetlands, providing additional coastal protection services from storm surges and other extreme events [47]. For example, Sun and Carson [49] reported that the protective effects of 1 km 2 of coastal wetlands saved an average of $1. Coastal wetlands are important environments in climate change mitigation as well, particularly as blue carbon habitat that sequesters carbon dioxide and other greenhouse gas emissions [50]. In addition, restoration of blue carbon habitats increases coastal carbon storage areas [48]. While often effective, soft engineering restoration strategies such as those noted above are not as widely used today as hard engineering shoreline structures such as bulkheads, revetments, and seawalls, which typically alter water flow, truncate habitats, sever ecosystem connectivity, reduce species diversity, and interfere with landward migration of low-lying habitats in the face of rising sea level. In most cases, the implementation of living shoreline stabilization includes hybrid components (i.e. both soft and hard structural materials) along shorelines that can increase connectivity of ecosystems [51].
Restoration is a challenging process with mixed outcomes [41]. This is so because of significant vagaries in environmental conditions of estuarine and coastal marine environments, difficulties in differentiating anthropogenic and natural-mediated impacts, and the financial cost of conducting habitat and ecosystem recovery [37]. One view is that altered natural ecosystems do not recover from human-induced pressures unless secondary succession returns them to a pre-existing condition or state [35]. There are three pathways of recovery: 1) Ecological restoration can increase the capacity of ecosystems and biotic communities to adapt to shifting environmental conditions. Although restoration programs have not been viewed as very cost effective, De Groot et al. [54] found that when appropriately analyzed, most ecological restoration projects were not only profitable but also high-yielding investments. Many of these projects were vital both for recovery of biodiversity and ecosystem goods and services useful to people [55].
Across a broad range of biomes and ecosystem types analyzed, coastal wetlands and inland wetlands offered the most value for restoration investment in absolute terms.

Marine Protected Areas and Refugia
One way of conserving coastal environments is to establish protected areas through management programs that prohibit human activities stressful and potentially destructive to biotic communities and habitats. Another way is through coastal land purchases that can limit land-based pollutant inputs and other development impacts on estuarine and coastal marine environments [56].
Coastal management is also identifying and protecting refugia, that is, areas having more favorable environmental conditions that render them less vulnerable to climate change disturbances or other chronic stressors, thereby strengthening local or regional ecosystem resilience and survival of organisms [57]. In addition, expanding marine ecosystem restoration to integrate social-ecological concepts Open Journal of Ecology will increase the scope of restoration science and facilitate recovery of degraded habitats and impacted biotic communities. Restoration of coastal ecosystems has evolved over the past 50 years to consider social elements and ecosystem service outcomes. For example, Martin [58] documented the emergence and significance of the social dimensions of ecological restoration. Coastal marine ecosystem restoration is part of an ongoing management strategy to address anthropogenic impacts, although there are perceived negative aspects such as their high cost, limited spatial extent, and narrow goals [41].
Marine Protected Areas (MPAs) are selected areas intended to protect all or part of a marine ecosystem [59]. They are an important tool to conserve, restore, and sustain estuarine and marine environments by protecting threatened ecosystems and their resources from intrusive anthropogenic activities. As such, MPAs are effective for restoring marine biodiversity, enhancing fisheries, and ecosystem services [60]. These selected areas, which can take various forms such as refugia to research sites, are set aside to ensure that habitats and resources implemented as fully or highly protected, no-take MPAs [60]. Highly protected MPAs are areas in which extractive and destructive human activities are banned [60]. They offer protection from fishing, mining, and habitat destruction. No-take MPAs are effective in restoring biomass and structure of fish assemblages. According to Sala and Giakoumi [59], the biomass of whole fish assemblages was on average 670% greater within marine reserves than in adjacent unprotected areas, although fish biomass in partially protected MPAs was less, that is, 183% greater than in unprotected areas. As such, MPAs can contribute substantially to three major goals: 1) biodiversity protection; 2) food provision; and 3) carbon storage, the latter playing a positive role in climate change mitigation. In addition, MPAs can protect other ecosystem services as well.
Halpern [62], however, presented reasons why MPAs fail to meet their full environmental protection targets. As noted by Katsanevakis et al. [20], it is not unusual for MPAs to fail to achieve target goals due to poor design, insufficient

Regulatory Frameworks
Legislative frameworks exist to protect and conserve estuarine and coastal ma- Some national legislation, such as the National Environmental Policy Act and the Clean Water Act and its amendments in the USA, provides sweeping protection of water quality, habitats, and organisms from pollution and other environmental impacts. These laws enable federal government agencies (e.g. US Environmental Protection Agency) to regulate human activities that are damaging to coastal ecosystems, threatening to organisms, and an impediment to habitat and ecosystem sustainability. Through this federal government process, the legislative acts and policies support ecosystems services and interests of the public for healthy and sustained estuarine, coastal, and ocean waters.
The Estuary Restoration Act (ERA) became law in the USA in 2000 and was amended in 2007. This legislation established a national estuary restoration strategy consisting of a coordinated and integrated federal approach, also involving non-federal partners, to restore damaged estuarine habitats [37]. The environmental legislation and policies targeting coastal problems in the USA have been widely successful, as has the integrated implementation of the EU directives through time [65].
International and regional agreements, together with legislative instruments at Open Journal of Ecology national and state levels and effective policies, administration and management strategies, exist to protect and conserve estuarine, coastal, and marine environments through an integrated ecosystem approach to managing maritime activities [2] [20]. They address anthropogenic pressures and impacts on estuarine and marine environments, which is relevant to ecosystem-based management practices effective for the preservation of ecosystem services and achieving environmental sustainability [65] [66] [67]. Elliott et al. [5] and Katsanevakis et al. [20]

Conclusions
A major challenge of integrated/interlinked ecosystem-based management of estuarine and coastal marine environments is to assemble the elements of a holistic approach necessary for successful and sustainable ecosystem components [5] [26]. A need exists for effective science-informing policy and policy-informing science and recognition of the limitations of each [16]. There is also a need for natural and social scientists and policymakers to work more collaboratively on the complex coastal environmental problems that currently exist and are worsening in many regions due to escalating climate change effects [19]. If these approaches are successful, the outlook for improved conditions of estuarine and coastal marine environments is a positive one.
This article examines the management strategies and legislative frameworks that address anthropogenic drivers of change and impacts in estuarine and coastal marine environments. The conclusions are as follows: 1) Numerous anthropogenic drivers of change affect estuarine and coastal marine environments, and various management strategies and legislative frameworks are in place to address them.
2) The main goal of estuarine management is to protect biotic communities and habitats from adverse effects of human activities and from changes that pose a threat to ecosystem structure, functioning, and sustainability.
3) Ecosystem-based management of estuarine and coastal marine environments is a holistic strategy that considers the entire ecosystem, including human activities. Open Journal of Ecology 12) International and regional agreements, as well as legislative instruments at national and state levels together with policies, administration and management strategies, are in place to protect and conserve estuarine, coastal, and marine environments through an integrated ecosystem approach to managing maritime activities.