Two Sides of the Same Coin: A Theoretical Framework for Strong Sustainability in Marine Protected Areas

Abstract

In 2014, the Italian Ministry of the Environment and Protection of the Territory and the Sea (MATTM) launched the “Environmental Accounting in the Marine Protected Areas” (EAMPA) project, which proposed a new accounting model for Marine Protected Areas (MPAs). The model foresaw the integration of ecological and economic components in classical accounting schemes through the quantification of stock and flows embracing both the perspectives. The project, which ended in 2019, allowed the testing and the realization of the multidisciplinary framework. Later, in the context of the EU Interreg “Integrated management of ecological networks through parks and marine areas” (GIREPAM) project, an upgraded version of the EAMPA framework was developed, including additional but fundamental components leading to a more detailed and complete assessment as well as a better theoretical definition. The definitive management framework is outlined through the creation of the two parallel paths, but it provides as a final result three balances from the strong sustainability perspective: ecocentric, anthropocentric and integrated. To ensure that sustainability is obtained, all the three balances must guarantee a positive net benefit for humans and nature alike.

1. Introduction

Beyond the well-known categories of human, social and financial capital, a fifth one was identified in the 1990s: the natural capital [1,2,3,4,5,6]. Natural capital comprises all natural resources required for economy and human development [7].

In the context of the ecological functions derived from natural capital, humans often do not use all the functions, or they use them indirectly, but our survival and well-being depend on them. Natural capital should therefore be at least kept constant in terms of quantity and quality from a precautionary viewpoint. The deterioration or compromising of a function can result in severe and unforeseeable consequences, which may not be immediately felt by humans, but affect components that humans use.

Ecosystem functions arise from the interactions among natural capital components, and they are able to generate goods and services for humans and other species [8].

Ecosystem goods (e.g., food) and services (e.g., ability to assimilate waste) can then be defined as the benefits that humans obtain, directly or indirectly, from ecosystem functions [9,10]. Some examples about differences between the three definitions are shown in

Table 1. Natural capital, functions and services: examples.

Component of Natural Capital	Ecosystem Function	Ecosystem Good or Service
Ecosystems	habitats for all species	recreation for humans
Grass	food production for herbivores	meat production for humans
Rain	freshwater availability for all species	production of water for human consumption

.

Ecosystem functions existence is then completely independent from humans’ perception and awareness of them. On the contrary, ecosystem services are defined according to the benefits they bring to mankind.

Over time, the concepts of functions and services have both been classified in order to make them clearer. The classification by [9] identified 17 main categories. Later, based on this first schematization, De Groot et al. [11] proposed a full framework for the identification and classification of both ecosystem functions and services. Specifically, four ecosystem functions categories were defined by [11]: regulation functions, habitat functions, production functions and information functions.

Relationships between functions and services can be extremely complex: there is not necessarily a two-way relationship between ecosystem functions and services. A service usually depends on a set of functions, and a function contributes by creating a group of services for humans. Ecosystem services can be defined as the end products of ecosystems: the share of ecosystem functions exploited by humans and the economic or social benefits produced.

Since 2000, different ecosystem services classifications have been proposed. The classification of the working groups of the Millennium Ecosystem Assessment (MEA) still remains a goal to be accomplished [10]. Ecosystem services can be split into four macro-categories: supply, regulation, cultural and maintenance services.

The MEA classification was followed by The Economics of Ecosystems and Biodiversity (TEEB) one [12] is also organized into four macro-categories. One of the most important findings of the TEEB initiative was the creation of the so-called “ecosystem services cascade”. This cascade is the pathway from the ecosystem structure and processes to human well-being, a framework where the ecosystem services are the link that joins ecosystems with economics and discloses the connection between our economies and natural capital stocks [13].

The most recent classification, formulated by the European Environment Agency (EEA) and the United Nations Statistical Division (UNSD) working group, known as System of Economic and Environmental Accounts (SEEA), is The Common International Classification of Ecosystem Services (CICES), which standardizes existing categorizations to make them comparable [14,15].

The CICES classification identifies three service categories:

• Supply services: tangible and marketable goods (materials and energies) directly consumed by humans and produced by ecosystems;
• Maintenance and regulation services: those functions that control and modify the abiotic and biotic compartments of ecosystems and from which environments suitable for human life originate;
• Cultural and social services: all non-material outputs of ecosystems with symbolic, cultural and intellectual importance.

An ecosystem service can bring multiple benefits; for example, a food resource can generate both income and well-being (such as nutrition, sensory fulfillment or social identity values ascribed to some traditional foods).

The anthropic category and the related economic system ascribe a value only to the final benefit obtained from the fruition off ecosystem services, since it is the only one that humans perceive. Nonetheless, benefits can be provided by nature only if the natural capital stock is maintained intact in terms of quality and quantity: the service flows (and the corresponding benefits, economic and otherwise) can be ensured to present and future anthropic generations at the current level only if natural capital is preserved [16].

As a consequence, in terms of conservation, the goal of institutions and governors should be to remain precautionary about reaching a “very strong” sustainability. In this context, Turner [17] defined four sustainability typologies, from very weak to very strong. A very weak sustainability theory is based on the complete substitutability of manufactured and natural capital. Very strong sustainability, on the contrary, relies on complete non-substitutability and on keeping natural capital (and all of its components ) untouched [18]. Embracing the cascade theory, and from a weak sustainability perspective, welfare will hopelessly decrease if different types of capital are not perfectly substitutable [19]. On the contrary, if strong sustainability is reached, it can be considered and evaluated to gradually shift toward the weak, but not vice versa. This is why the measure of natural capital is essential. This measure must be realized first from an ecological point of view and only at a later time in monetary terms (to compare it with other capital types if necessary).

To set up an operational management and to guarantee the maintenance of resources at least at the current level, it is then essential to provide managers of the territory and decision-makers with effective tools.

For this purpose, financial accounting, which assesses the economic performance of a system (e.g., a company or an institution) [20], must be coupled with environmental accounting, i.e., a balance that is realized through the quantification of material and energy flows within a defined system and expressed in physical units. Biophysical approaches, based on the quantification of physical features, can be employed to realize environmental accounting [16,21,22,23,24]: they assess a cost of production or the so-called donor-side perspective [25,26,27,28]. If nature is considered a system, it can be described with a simple input–output representation [29]. A user-side approach focuses on outputs and on the identification of users that exploit them, while biophysical methods are founded on the assessment of inputs. These methods allow a value to be ascribed to a good or a service by measuring intrinsic characteristics, in a way that is completely detached from market laws. Biophysical methods coupled with economic ones can be the used to obtain a complete assessment of a system [30].

As a consequence, in order to obtain true sustainability, it is then fundamental to connect the two (donor/user) sides without neglecting both the economic and the ecological perspectives.

2. The EAMPA and GIREPAM Projects

The Italian Ministry of the Environment and Protection of the Territory and the Sea (MATTM) launched in 2014 the “Environmental Accounting in the MPAs” (EAMPA) project addressed to all Italian Marine Protected Areas (MPAs).

Coastal marine ecosystems are key systems providing high value services and benefits [31,32,33,34,35,36,37]. Unfortunately, coastal areas are threatened by urban settlements and industrial and tourist impacts, and the link between ecosystem health and human well-being is often underestimated [38]. The consequences of anthropic impacts on coastal areas generate a wide loss of habitats [39,40,41,42,43,44,45,46].

In this context, marine protected areas (MPAs) plays a fundamental management role for effective conservation [47,48,49] and the reduction of ecosystem degradation. Proper management of MPAs with reference to specific conservation goals can be crucial to both protecting these ecosystems and generating benefits for humans [50,51,52,53,54].

Providing management tools able to assess MPAs’ efficacy should become a priority to avoid the so called “paper parks” [55].

The EAMPA project proposed a new accounting model for MPAs based on the quantification of the biophysical and monetary value of the natural capital and of the variations in the ecosystem functions and the service flows originating from it. The project, which ended in 2019, allowed the testing and realization of an innovative multidisciplinary framework. After that, an upgraded version of the EAMPA framework was developed, in the context of the EU Interreg “Integrated management of ecological networks through parks and marine areas” (GIREPAM) project, which started in 2017 and ended in 2020. Specifically, some components that were neglected during EAMPA were added to the framework, permitting a more detailed assessment as well as a clarification of the framework itself. The final integrated management framework is outlined through the creation of two assessment paths corresponding to two accounting procedures: the ecocentric and the anthropocentric one. The paths are composed of different phases [56,57,58], which are represented in Figure 1 and described in detail in the following paragraphs.

3. Natural Capital Assessment

3.1. Data Availability Inventory

The operations necessary to start the project are:

• The collection and management of data through computerized platforms that allow for simpler and more rational dynamic management of the collection phase;
• The rationalization and alignment of the existing cartography relating to basic cartography (e.g., perimeter, bathymetry and type of biocoenosis), anthropic activity maps or maps regarding specific issues of the MPA;
• The identification and subsequent calculation of the surface of each biocoenosis of the MPA;
• The analysis of fish fauna data obtained through visual census projects;
• The preliminary quantification of the biomass values (through bibliographic research and/or consultation of in situ studies) of the different taxa considered as representative of the benthic communities associated with biocoenosis.

At the end of these preliminary operations, an accounting of the MPA natural capital, in both biophysical and monetary terms, is carried out.

3.2. Benthic and Fish Community Natural Capital Assessment

The procedure to realize the assessment has been described in detail in [28] and applied in several case studies [57,59,60,61,62,63,64,65,66,67]. Out of the existing biophysical methods [25,26,27,28], emergy analysis has been selected. Emergy accounts for the total amount of energy directly or indirectly used to generate a product. To obtain and maintain a natural good or service, nature must perform a series of transformations requiring energy and materials. The biosphere is a closed system powered by a unique energy type: solar energy. As a consequence, the work performed by nature through the whole chain of transformations is assessed as the total amount of equivalent solar energy. In such a way, the value of environmental goods and services is calculated in biophysical terms and as a production cost to obtain them [68].

To quantify the MPAs’ natural capital, the first step is represented by an inventory of all communities existing there. Once the communities are identified, two main pieces of information are necessary: the surfaces occupied by each community and the biomasses of the organisms living on this surface. This information can be obtained from cartography, literature review or specific surveys.

Next, all inputs (energy and materials) required to generate the biomass stocked in each community must be assessed and then converted to emergy units. Biomass originates through the food network, starting from photosynthesis: all inputs required to initiate and continue the photosynthetic process must be assessed (carbon, phosphorus, nitrogen, sun, wind, rain, tides, currents and runoff). When all inputs are assessed in raw unit flows, their value is transformed into biophysical emergy units (sej) through conversion factors (UEVs) found in the literature [68].

Once the emergy value of each community is calculated, the sum of all community emergy values gives the MPA full natural capital value in emergy biophysical units (sej). This value is then translated into a monetary equivalent by means of an appropriate conversion factor named the Emergy-to-Money Ratio (EMR) [57,69]. The EMR is obtained as the ratio between the total emergy feeding a nation and its gross domestic product in the same year [70]. The EMR represents the average amount of emergy needed to generate one unit of money in the national economy being considered [68]. The monetary value of natural capital for each community and of the MPA is then calculated as the ratio of the emergy value and the EMR. The conversion of natural capital in monetary units is not compulsory, but it has the merit of making results easily conveyable from scientists to managers and also from managers to general public or key stakeholders (e.g., tourists or operators).

4. Ecosystem Services Identification

Ecosystem services under study must be identified and listed. In the EAMPA project, the CICES (Common International Classification of Ecosystem Services) scheme was employed for this purpose. A core of ecosystem services was selected to be analyzed in the project and framed in the CICES perspective, as shown in

Table 2. List of selected and evaluated services framed in the context of the CICES scheme.

Section	Division	Group	Class	Simple Descriptor	Specific Service Evaluated
Provisioning (biotic)	Biomass	Wild animals (terrestrial and aquatic) for nutrition, materials or energy	Wild animals (terrestrial and aquatic) used for nutritional purpose	Food from wild animals	Professional artisanal fishing
Cultural	Direct, in situ and outdoor interactions with living systems that depend on presence in the environmental setting	Physical and experiential interactions with natural environment	Characteristics of living systems that enable activities promoting health, recuperation or enjoyment through passive or observational interactions	Watching plants and animals where they live; using nature to destress	Tourist use as direct benefits and economic impacts from: bathing tourism; pleasure boating; recreational diving; sport and recreational fishing
		Intellectual and representative interactions with natural environment	Characteristics of living systems that enable scientific investigation or the creation of traditional ecological knowledge	Researching nature	Scientific activity
			Characteristics of living systems that enable education and training	Studying nature	Educational activity
Regulation and maintenance	Regulation of physical, chemical, biological conditions	Atmospheric composition and conditions	Regulation of chemical composition of atmosphere and oceans	Regulating global climate	Climate regulation through carbon storage by autotrophs

[71]. These services are (1) wildlife exploitation for food purposes through professional artisanal fishing; (2) tourist use such as recreational activities such as bathing tourism, pleasure boating, recreational diving, sports and recreational fishing; (3) educational activity; (4) scientific activity; and (5) climate regulation. Even if the list of ecosystem services provided by coastal and marine ecosystems is much longer [64], this core selection has been obtained based on two principles: (a) the relevance related to the set-up of the conservation actions taken by the MPA; (b) the possibility to effectively quantify them. This selection is also reported within the official National Account for the natural capital of the Italian Ministry in the section dedicated to the MPAs [72]. Clearly, an appropriate list of services must be detected for each system under study.

5. Balance Assessment

Balance implementation is realized on an annual basis and draws on the model developed by various authors [73,74,75,76,77,78]. The main items composing this balance are shown in

Table 3. Ecological–economic balance scheme, costs and benefits are per year.

Ecosystem Service	(A) Costs			(B) Benefits
	(A1) Ecocentric		(A2) Anthropocentric	(B1) Ecocentric	(B2) Anthropocentric
	Direct	Indirect	Financial	Protection	ES Fruition	Protection	Financial
Wildlife exploitation for food	professional artisanal fishing	professional artisanal fishing	current expenditures + capital expenditures + reallocation of funds	fish secondary production	professional artisanal fishing		current revenues + capital revenues + reallocation of funds
Tourist use	sport and recreational fishing	sport and recreational fishing		fish secondary production	sport and recreational fishing
	pleasure boating	pleasure boating			pleasure boating
	recreational diving	recreational diving		coralligenous secondary production	recreational diving
		bathing			bathing
Scientific activity		MPA functioning			studies and projects
Educational activity					students activities
Climate regulation						CO2 sink
Total Costs (A1 + A2)
Total benefits (b1 + b2)
Aggregated net balance (b − a)
Ecocentric net balance (B1 − A1)
Anthropocentric net balance (b2 − a2)

, which comprises costs and benefits, each of which is split into its ecocentric and anthropocentric components. The ecocentric and anthropocentric costs and benefits are obtained for each ecosystem service. Ecocentric costs are calculated here with a biophysical, ecological approach as the annual quantity of natural capital removal: they are negative impacts, such as damages, impairments or withdrawals, generated by the fruition of the ecosystem services. This includes a donor side perspective, focusing on natural capital, which is the core and the starting point of the cascade and the base from which ecosystem services arise. These costs are assessed in biophysical units. On the other hand, ecocentric benefits are positive impacts on the environment, which in this context are mainly due to protection. Ecocentric benefits are calculated with a donor-side approach. In particular, the net ecological production of target components (e.g., a species or a group of species) of the studied ecosystems is assessed in biophysical units. Ecocentric costs and benefits, when assessed in biophysical units, are later transformed into monetary equivalents following the same methodology described for natural capital. Anthropocentric costs and benefits include three components: (1) the annual gains for humans associated with the establishment of the protection regime; (2) the direct and indirect financial gains from the fruition of ecosystem services; and (3) the financial flows received and spent by the MPA. To assess costs and benefits, a set of data must be collected and processed. The required data deal with the fruition of ecosystem services. The necessary information is gathered mainly through questionnaires and interviews campaigns, and the settlement or improvement of the MPA authorization procedure (this latter is handled by the managing body).

Questionnaires and interviews must be administered to both users and economic operators if both categories are present. The following information comes from users: daily and annual presence, habits and behavior during their stay in the MPA or during their holiday (including at least a visit to the MPA), consumption of resources during their stay at a tourist or service facilities or in the local territory (e.g., electricity, fuel, or water), generation of waste or emissions, and cash expenses. Questionnaires and interviews for economic operators allow data to be obtained about facilities’ resource consumption, financial income, financial costs and daily and annual presence of users.

The management procedure of protected areas often foresees activities undertaken by users or operators to be mandatory as authorized by the managing body. Users or operators apply for permission to carry out the activity; the managing body, verifying the compliance with some requisites foreseen by the MPA regulation, issues the permission based on a payment. The permission system, if organized with a standardized procedure, is a fundamental tool to monitor and control the access to the MPA. The permission system can be implemented at different levels of automation and detail, from very basic (e.g., including only electronic payment) to advanced computerization and rationalization (e.g., recording all data related to the type of activity and in-depth information about the users and operators). According to the level of progress of the permission system, it provides information about MPA attendance and the activities that users carry out within. The authorized activities are generally: bathing, fishing (commercial, artisanal and recreational), recreational boating and diving. In addition to costs and benefits related to ecosystem services enjoyed by users and operators, inputs associated to the functioning of MPA institutional activities (e.g., administrative and scientific activity) need to be counted: these are costs associated with resources consumption required to keep MPA vital such as day to day management. Without these costs imposed on the environment the entire process would not happen.

5.1. Ecocentric and Anthropocentric Costs

Ecosystem services fruition can be performed only if a certain amount of natural and man-made resources is consumed by services’ users. This exploitation affects natural environment since (1) the resources are withdrawn and prevented from having alternative uses and (2) their use generates harmful emissions.

5.1.1. Ecocentric Costs

Ecocentric costs are classified here as direct and indirect. Direct ecocentric costs are those impacts on the environment occurring within the MPA borders. Indirect ecocentric costs, conversely, occur outside the MPA, even very far from its boundaries, but they are absolutely necessary to enjoy the studied ecosystem service. Ecocentric costs are assessed here with emergy analysis and then from a biophysical donor-side perspective. The calculation of direct costs, not foreseen in the original formulation of the EAMPA project, has been included in the framework subsequently in the context of the GIREPAM project. In order to assess these costs, it is necessary to realize an inventory of all the resources exploited by users enjoying the service and to acquire a deep knowledge about their behavior, also in order to localize the impacts.

(a)

Direct ecocentric costs

Direct costs are imposed on the MPA environment by only some of the services reported in Table 2, i.e., wildlife exploitation and three components of tourist use (recreational boating, diving and recreational fishing).

The direct impact of the wildlife exploitation service is evaluated as the biomass withdrawn as annual fish catches realized by professional fishermen. The annual catches are calculated by providing operators with log books that they must deliver to the MPA in order to be allowed to fish in the MPA itself. Moreover, periodic monitoring campaigns and reports are performed. The number and the biomass weight of species taken by fishermen are then assessed [79,80,81]. The biomass is then transformed into emergy and monetary units according to the procedure proposed by [57] for natural capital value assessment. The procedure foresees different steps: (1) the assessment of the primary production: the withdrawn fish biomass is generated with a trophic network, providing the necessary food sources for the fish themselves [82]—this network is maintained, at its basis and in space and time, using a primary production that can be calculated by modeling the system; (2) the translation of this primary production into emergy units: this step is realized by reckoning all the resources required to generate it (e.g., nutrients). A detailed description of the procedure is reported in [79,81].

Tourist use direct cost is estimated for boaters, divers and recreational fishermen. Some communities within the MPA are exposed to the impact of boaters and divers: these are Posidonia oceanica and coralligenous communities. Specifically, boaters exert an impact on P. oceanica meadows when anchoring on them, since the dragging of the anchor may dislodge plant rhizomes or leaves. This mechanical damage can be huge, and it may even endanger the survival of the meadows and provoke changes in the trophic structure of the meadow community [82,83,84,85,86,87,88]. Divers impact coralligenous communities through physical contact with sea-bottom. The impact of diving is usually neglected, since it is traditionally considered an environmentally friendly activity, generating revenue without harming the marine environment. Nonetheless, diving activities, in recent decades, have increased, which may cause direct effects on coralligenous communities, in particular, on benthic calcareous organisms, which are often characterized by high fragility and low growth rates [84,85,89,90,91,92,93]. The cost ascribed to boaters and divers is then assessed in terms of the removal of sensitive communities and of the corresponding natural capital. In order to evaluate the amount of this phenomenon, a careful recording of users’ yearly presence at the MPA must be performed. To this purpose, the MPA can follow two procedures, which work better if performed simultaneously: (1) on-field monitoring campaigns; (2) the establishment of an access control system such as an authorization system in order to schedule all users and track and record their MPA attendance frequency. Later, an average impact is ascribed to each presence (per presence removed or damaged surface). The total amount of surface that boaters’ and divers’ activities impact is then obtained by multiplying the number of presences by their per-presence damage. To obtain the corresponding quantity of natural capital removed in both biophysical and monetary terms, the impacted surface is then multiplied by the natural capital value per unit area [60,61,62,63,64,65].

Additionally, the impact of recreational fishing falls within the category of tourist use services, given the playful nature of this activity. Nonetheless, the cost imposed on nature is assessed with the same methodology employed for wildlife exploitation by professional artisanal fishermen [79].

(b)

Indirect ecocentric costs

Indirect ecocentric costs are quantified as the total amount of resources exploited for the fruition of all services provided by the MPA (bathing, boating, diving and fishing).

The considered resources are fuels by category (e.g., gasoline and methane), electricity, water, manpower, materials and equipment.

The consumption of these resources generates impacts evaluated by two approaches applied together: (1) the effect on global warming (evaluated as the carbon footprint) associated with greenhouse gas emissions due to resources consumption, and (2) the effort of the environment (evaluated with emergy analysis) required to obtain necessary resources through transformation chains.

The quantities of resources consumed, each expressed in its specific unit of measure (e.g., grams, joules, kilowatt hours), are assessed. Later, these amounts are transformed into the corresponding weight of CO₂ equivalents emitted (for calculation of carbon footprint) and into equivalent solar energy (sej, for the calculation emergy analysis).

Greenhouse gas emissions are quantified in terms of tons of equivalent carbon dioxide generated by energy and materials used while performing activities. For the estimation of these emissions, different databases can be employed (e.g., the Fourth Assessment Report of IPCC [94]). The considered conversion factors must take into account the greenhouse gas emissions generated during the entire life cycle of an item.

Emergy analysis expresses resources required for the fruition of ecosystem services in terms of the units of measurement of sej [95,96,97]. For this purpose, appropriate UEVs must be found in the literature.

The total annual impact is calculated, according to both approaches, as the sum of contributions by all the resources exploited in a year. This total impact is then expressed into equivalent monetary units through the use of appropriate conversion factors. For the carbon footprint, the social cost of carbon (SCC) can be used to monetize emissions. The SCC method is able to associate the monetized damage to each incremental increase in terms of carbon emissions in a given year [98]. The assessed damages comprise changes in agricultural productivity, human health, property damages from increased flood risk and the value of ecosystem services due to climate change, even if other damage types are considered. For emergy analysis, the same EMR used for natural capital assessment is employed. The monetization, even if not compulsory, makes it easier for the policy makers and the general public to understand information and results. Moreover, if results are expressed in monetary units, they can be included in the cost–benefit analyses, making ecocentric cost evident and allowing mitigation measures to be suggested.

5.1.2. Anthropocentric Costs (Financial Costs)

Anthropocentric costs are represented by financial costs, i.e., the expenses associated with the maintenance of the MPA (e.g., purchase of goods and equipment, ordinary maintenance of buildings and structures).

5.2. Ecocentric and Anthropocentric Benefits

In the final wording of the framework, benefits are assessed with both ecocentric and anthropocentric approaches. The ecocentric benefits, not included in the initial EAMPA scheme, were formulated within the GIREPAM project. Ecocentric benefits are intended as a profit for nature and are then assessed as the monetary equivalent value ascribable to the annual biophysical production of MPA communities. This represents the donor-side perspective of providing benefits. The anthropocentric benefits are conversely assessed as annual economic benefits obtained by humans as a consequence of the fruition of ecosystem services. The anthropocentric benefit accounted for is the real and virtual gain obtained by MPA attenders, directly arising from the enjoyment of nature: these benefits are then estimated from a user-side perspective.

5.2.1. Ecocentric Benefits

Ecocentric benefits are the gains that nature obtains from the protection regime imposed by humans. The ecocentric benefits are accounted for as regenerative capacity of the MPA communities and are assessed as the natural capital annual production.

Ecocentric benefits include, at this point, only those communities exposed to a direct ecocentric cost, in order to evaluate if the MPA ecosystem can tolerate the impact of human activities.

The benefits are then assessed as secondary production generated by organisms living in the MPA communities according to the following equation:

Net secondary production = S_{i = 1}ⁿBi(Pi/Bi − Mi)

where i are the trophic groups composing the biocenosis as explained by [57,63], Bi is the biomass of the group i, Pi/Bi is the production/biomass ratio and Mi is the mortality rate of the considered organism i.

The production/biomass ratio for organisms can be obtained from the literature (e.g., for marine organisms of the MPA [57,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,128,129,130,131,132,133,134,135,136]).

Mortality rate is calculated with an appropriate algorithm according to the category of organisms; for instance, in the MPA case, two different equations are used, respectively, for benthic groups and for fishes, as shown in

Table 4. Calculation formulas and parameters for mortality rates assessment.

Group	Formula	Parameters
Benthos	Mi = 0.082 + 0.925 (Pi/Bi)	Pi/Bi = production/biomass ratio
Fishes	Maximum value between: FishBase (http://www.fishbase.org/) Mi = 1.5 × ki [137,138] Mi = 4.899 × tmax−0.916 [139,140] Mi = 4.118 × ki × 0.73 × linf−0.33 (alternative to 3 if tmax is unknown [139,140])	ki = von Bertalanffy’s growth coefficient for the considered species i tmax = maximum age of the considered species i linf = lower length of the considered species i

.

5.2.2. Anthropocentric Benefits

The anthropocentric benefits are arranged in three categories: (1) ecosystem services fruition, (2) protection and (3) financial.

(a)

Ecosystem services fruition benefits

These benefits are calculated as profit from the exploitation of nature according to the human side. They come from the fruition of the following ecosystem services: wildlife exploitation for food purposes and tourist use.

As a consequence, these benefits are estimated using traditional economic methods for the valuation of ecosystem services, which are based on the neoclassical economic framework and market laws of demand and supply of a substitutable good or service.

Economic methods are typically and intrinsically user-side and instrumental (or utilitarian), since for economics, a value can be ascribed to ecosystems, functions and services only if they are exploited by humans. In particular, according to economic theory, something has value only if it is useful to someone or something else and also only if it is exchanged on the market. The value on the market depends on trade-offs made by individuals in the substitution of a good with others and is driven by individuals’ preferences.

The methods for measuring the calculation of economic value of ecosystem goods and services are divided into two categories: revealed preference and stated preference methods. Revealed preference methods estimate the value of the studied service through observations of users’ behavior, while stated preference methods employ responses to hypothetical questions [141,142].

If the considered service is traded, its market price is used and it falls into the revealed preferences approaches [11]. If the service has no market, a price is indirectly estimated through related factors that do have a market.

There are various indirect market valuation techniques, such as household production cost (costs of cleaning or repair due pollution), avoided cost (costs incurred in the absence of the service), replacement cost (cost of replacing a service with a man-made system), averting behavior (expenditures to defend against negative effects of pollution), travel cost (money and time people spend traveling to the site where the service is enjoyed, typically employed for tourist use) and hedonic pricing (based on the idea that people are more willing to pay to live in areas with good environmental quality) [11,142,143,144,145,146].

Among the stated preference methods, the one with the most spread is contingent valuation (CVM), which is as much adopted as it is criticized. The CVM method foresees that people are directly asked about the value they ascribe to an ecosystem service (willingness to pay). The CVM is realized through a questionnaire or interview campaigns. CVM’s strength resides in its flexibility given that it can be applied for the estimate of any service. This flexibility also represents the main weakness of the method in terms of possible bias and reliability [143,144,147]. The main issue with CVM is the survey design. First, the population of stakeholders using or affected by the service must be identified and assessed. Then, a sound sampling strategy must be designed and an appropriate questionnaire formulated [147].

The main question about the willingness to pay can be formulated using several options for the question format (e.g., referendum format or open-ended) according to the context, the type of users and the ecosystem service analyzed.

The benefit coming from wildlife exploitation for food purposes service is quantified using the monetary value associated with the catches by professional fishermen through market prices (catches per species by market price per weight units of each species).

Tourist use refers to the physical and experiential use of natural resources such as plants, animals, marine and terrestrial landscapes. Tourist use benefits humans in two ways: (1) through the hedonistic experience of users; (2) as an economic impact.

The profit due the hedonistic experience of users is assessed using CVM for each user category: recreational fishermen, divers, boaters and bathing users. An appropriate questionnaire must be administered to user samples for each category. The questionnaire must investigate how much they are willing to pay to enjoy the specific ecosystem service (in addition to the expenses already incurred).

The benefits of economic impacts comprise direct, indirect and induced economic revenues associated with the activities of the considered user categories (recreational fishermen, divers, boaters and bathing users), since they act as tourists in the local economy. The direct effect is given by the expenses incurred by users on the local territory, which would not have materialized in the absence of the ecosystem services (e.g., food and accommodation). The indirect effect is the effect on supply companies that respond to the greater local demand associated with the direct effect (e.g., food industry, maintenance). The induced effect derives from the change in the level of residents’ income due to the greater demand for work. The direct effect is evaluated through questionnaire campaigns, while indirect and induced effects are assessed with suitable multipliers generated by administrative and statistical national or local bodies [148,149,150].

(b)

Protection benefits

Protection benefits derive from the augmented ability of MPA communities to generate benefits for humans as a consequence of the protection regime. For MPAs, the benefit of climate regulation is evaluated. This benefit depends on the ability of local communities to play a role in the regulation of the greenhouse gas cycle. The marine system, in particular, accumulates CO₂ that would otherwise be released into the atmosphere. The benefit is calculated by assessing the CO₂ stocked yearly in the P. oceanica meadows in the MPA. The monetary value of the service is calculated by multiplying the quantity of the CO₂ stocked by the SCC value.

(c)

Financial benefits

These benefits are financial revenues of the MPA coming from institutional financing and self-financing. Institutional financing covers funding from national and regional administrative bodies. Self-financing includes, for instance, funding from European, national or regional scientific projects, payments for the issuance of permits to users and operators, penalties for disregarding MPA regulation by users and operators, and sales of gadgets.

5.3. Costs and Benefits Comparison and Net Balance Assessment

Costs and benefits associated with each service allows a final balance to be obtained; specifically, three main results are obtained, as shown in Table 3:

• Aggregated net balance = B − A;
• Ecocentric net balance = B1 − A1;
• Anthropocentric net balance = B2 − A2

The aggregated net balance is a synthetic index of ecological and economic performances of the MPA: it is intuitively the simpler measure to obtain but not the most informative. The aggregated net balance is a weak sustainability indicator, since, in this case, the system’s condition is judged to be more profitable the farther the benefit is from zero. Nonetheless, without splitting the ecocentric and the anthropocentric pathways, even when the ecocentric costs are higher and greater than the ecocentric benefits, the aggregated benefit can be far from zero and positive. This means that, hypothetically, if the natural capital is depleted but the economic gain is pushed to the maximum, the aggregated benefit would not be able to detect the critical condition of the environmental compartments. Analogously, it can happen that anthropocentric benefits would be lower than costs but compensated by the ecocentric side. In both such cases, it is obvious that even if the MPA system, when observed with the rough view of aggregated balance, appears to be in a sustainable condition, it actually lies in an unsustainable state since it is not healthy for one of the two compartments. However, what does it mean then to be sustainable? The first definition was given in “Our Common Future” by the United Nations World Commission on Environment and Development [151]: “Sustainable development is development that meets the needs of the present generation without compromising the ability of future generations to meet their own needs”. This was an exquisite political definition, but it played a key role in bringing to the fore the concept of sustainability and starting a debate about it. The crucial concept driving Brundtland’s definition is “needs”, but needs for present and future generations vary greatly according to typically anthropocentric and user-side factors. Brundtland’s definition failed, then, in addressing the issue of scale, which is compulsory on a finite planet [152]. Fath, 2015 [152], then diversified between sustainable development and sustainability: in his opinion, the Brundtland definition refers to sustainable development and not to sustainability. Fath defines sustainability as a more functional concept given by the system’s capacity to endure and maintain vital functions and processes at the present level. Sustainability is then understood as a emergent system property that is independent from human actions, preferences, wishes, culture or any other human traits. Even if strictly not anthropocentric, the concept of sustainability is a pillar to obtaining the sustainable development of socio-ecological systems.

Traditionally, dealing with sustainability means pursuing profit generation (i.e., economic sustainability), but this can only lead to short-term success [153]. This became more and more obvious when the cascade theory was introduced and when the dependence on economy from nature was manifest.

Ecological sustainability and economic sustainable development can be then defined as follows: since the second exists only if the first is maintained, it should deserve higher priority to sustainability than to sustainable economic development [153,154]. The traditional approach claims that poverty causes environmental degradation that can be fought through a decrease in poverty, and a decrease in poverty can be obtained only through economic growth. This traditional approach must be reversed [155,156]. The depletion of natural resources can also imply, in fact, severe effects on the economy and on well-being, and it is now widely known that national accounting systems should be renewed in order to include the value of the changes in the environmental resources due to human activity [157,158]. For instance, the damage of climate change can result in widespread damage to the global economy, equal to a percentage of global products from 5% to 20% every year [159]. Roebeling et al., 2013 [160], estimated that 4500 km² of land had eroded between 1975 and 2006, with a further erosion of 3700–5800 km² projected by 2050. This level of erosion corresponds to a loss of EUR 0.7 billion of annual ecosystem services (at a constant price level from the year 2000) in the period 1975–2006, and EUR 1.5–2.2 billion in the period 2006–2050 [161].

Nonetheless, economic sustainable development must not be neglected: part of the inefficacy of the measures taken until today, in terms of the economy and the environment, is that they are mutually exclusive and conflicting. Economists are convinced that saving the planet will hurt the economy, while ecologists believe that saving the economy means we cannot save the planet. However, economy and environment are inextricably linked as the cascade of ecosystem services has highlighted [159]. For example, the economic cost of climate change (5–20% of gross domestic product (GDP)) should be avoided with an expense of 1% of GDP per year [159]. However, humans need financial resources to carry out conservation and restoration projects: in order to bring about a shift and transform the processes of production, it is necessary to increase incentives for the maintenance of ecosystems and reduce incentives that harm ecosystems [162]. Moreover, it is necessary to deepen the link between environmental consciousness and income inequality. At the early stages of economic growth, poverty is pervasive, environmental consciousness is low, funding cannot be allocated for the environment and environmental conservation policies are usually neglected. On the other hand, in the final stages of growth, both income level and environmental consciousness increase, as well as institutional quality, but the diffusion of technology contributes to lower environmental degradation [163]. Therefore, the interactions between environmental degradation, income inequality and environmental consciousness can play a fundamental role, but unfortunately they have not sufficiently been analyzed in the literature [164].

6. Concluding Remarks

Nowadays, it is finally clear that the challenges of sustainability cannot be the banner of ecologists or economists and that they require collaboration among different disciplines [165]. As a consequence, in this paper, a single system of sustainability balance, obtained through a disaggregated approach and achieved by two separate accounts (ecocentric and anthropocentric), is proposed. The anthropocentric net balance is a financial budget that takes into account yearly revenues that are directly and indirectly related to the fruition of ecosystem services. The ecocentric net balance takes into account the benefits associated with the protection regime (accounted for as an annual increase in natural capital), as well as costs imposed on the environment (such as the annual decrease in natural capital). If anthropocentric and ecocentric balances are considered and analyzed separately, a condition of unsustainability of one of the two sides is immediately detected. On the contrary, if the aggregated balance is considered without deepening the donor and the user sides, an (un)favorable condition of the anthropocentric or ecocentric side would be hidden by the combined result. Moreover, this means evaluating if the system is sustainable from a strong sustainability perspective, aiming at obtaining an increase in both human and natural capital. In such a context, a pivotal role is played by the accuracy of data gathering: therefore, the affordability of results is strongly dependent on automation, standardization and the computerized technology employed for information collection.

Through the proposed approach, if different components are tracked, critical compartments can be detected and management strategies suggested in order to set up more appropriate and efficient management strategies aiming at a real sustainability.