Economic Values for Coral Reef Conservation and Restoration in Florida

Abstract

Florida’s coral reef is the third-largest barrier reef system in the world and provides valuable ecosystem services, such as recreation and tourism, erosion protection, and other services. Florida’s reefs have been declining due to impacts from climate change, pollution, and other pressures. In response, various conservation strategies have been implemented, including education and outreach, growing corals in nurseries and transplanting them to degraded reef sites, and deploying artificial reefs. However, few studies have estimated an explicit value for different strategies to attain conservation goals. Understanding economic values for reef restoration and enhancement is needed to help inform decision-making and support marine policy. This study conducted a stated preference choice experiment survey to examine the way U.S. residents make economic trade-offs among different restoration strategies, including increasing coral cover, deploying artificial reefs, and limiting visitor access to reef sites. The results suggest that, on average, the economic value of increasing coral cover is about twice as high as the value of increasing the number of artificial reef sites. Economic values for reducing visitation were similar to values for increasing the number of artificial reefs. These results provide essential information to policy analysts concerning reef use, reef importance, and economic values for reef restoration.

1. Introduction

Coral reefs are among the most biodiverse ecosystems and provide valuable ecosystem services such as recreation, tourism, seafood, coastal protection, and cultural heritage, among many other benefits, as well as conservation and preservation values of those who may never visit a reef. In Florida, coral reefs are especially important to the state’s identity and economy. Florida’s coral reef represents the third-largest barrier reef system in the world, stretching for about 350 miles along the south Atlantic Florida coastline from Martin County to the Dry Tortugas (Figure 1). About 30% of the state’s population resides in the five Southeast Florida counties adjacent to the coral reef, with Miami-Dade, Broward, and Palm Beach being the three most populous counties in the state (U.S. Census Bureau, 2020). The coral reef is located within 1.5 km of the urban coastline, placing residents in close proximity of this delicate ecosystem [1]. Tourism plays a significant role in Florida’s economy, attracting people from all over the world for recreational diving, snorkeling, and fishing experiences. The combination of high tourism levels and dense coastal populations increases human interaction with the region’s coral reefs, creating both greater opportunities for people to benefit from the ecosystem services they provide and greater risks of human-induced stressors affecting the reefs. The loss of coral reefs would have far-reaching consequences for the region’s economy and culture, both of which are deeply connected to the local marine ecosystem. Thus, it is imperative for marine resource management to implement conservation or restoration strategies to sustain ecosystem functions and services.

1.1. Coral Reefs Under Stress

Scientific consensus suggests that Florida’s coral reefs have been declining for at least the last 40 years, with some studies suggesting that current coral cover is about 2% of what it was in past decades [2]. In recent years, coral populations have declined due to a mix of global and local factors, including rising ocean temperatures, more frequent coral bleaching events, outbreaks of coral disease, habitat disruption, poor water quality from land-based pollution, and other human impacts [3].

When exposed to environmental stress, corals may undergo a bleaching response, expelling the symbiotic algae they rely on for food and energy. In this weakened, bleached state, corals become more vulnerable to disease, although they often can recover if water conditions improve. In 2014–2015, a mass coral bleaching event occurred in Florida, coinciding with the outbreak of a highly contagious disease known as stony coral tissue loss disease (SCTLD) [4]. SCTLD has rapidly spread throughout Florida’s coral reefs and the wider Caribbean, impacting over 20 reef-building coral species [5]. Recent studies indicate a decline in coral diversity in South Florida, with species more tolerant of varying environmental conditions increasingly dominating the ecosystem [6].

In the summer of 2023, Florida’s coral reefs experienced the most intense heat event on record, causing widespread coral bleaching. This event led to the mortality of corals, including Staghorn and Elkhorn corals, which are federally designated as threatened and protected under the Endangered Species Act [7]. A severe disease outbreak in the early 1980s led to massive die-offs of both species, reducing their populations to less than one percent of their original size. Today, rising ocean temperatures may pose an even greater threat, with coral bleaching expected to increase in both frequency and intensity [8]. Without intervention, the last remaining wild Elkhorn and Staghorn corals in Florida could be completely lost. Mass coral bleaching can also lead to socioeconomic disruptions if user activities are affected. For example, divers and snorkelers can have different preferences for the types of coral reefs they experience and degradation of a reef site may lead to shifts in visitation patterns and where recreational activities occur [9]. Through these shifts in human use, economic benefits received in areas located near recreation sites can also be affected.

1.2. Conservation and Restoration Strategies

The decline in populations of multiple coral species has driven the expansion of coral restoration and conservation initiatives. In Florida, an array of strategies has been implemented, ranging from education and awareness campaigns, to growing corals in nurseries and transplanting them to damaged or degraded reef sites. Through Mission: Iconic Reefs, governments and other entities have planted over 30,000 corals in the Florida Keys, and aim to increase coral cover from 2% to 25% across seven iconic reef sites by 2025 [10]. The restoration sites were selected based on criteria for habitat diversity, range of human uses, geographic location, and a high probability of restoration success. Multiple stony coral species (i.e., Elkhorn, Staghorn, Star, Brain, and Pillar corals) will be out-planted and restored in these sites. Mission: Iconic Reefs also seeks to utilize local businesses and community involvement to promote responsible tourism and stewardship behaviors. A recent study by Allen et al. [11] found that 95% of household residents in Southeast Florida support efforts to restore damaged coral reefs.

Other reef conservation strategies in Florida include the deployment of artificial reefs. Since the 1940s, over 3800 public artificial reefs have been placed along Florida’s coast, about 18% of which are in Southeast Florida counties [12]. Artificial reefs can provide additional habitats for fish and other marine species, serving as potential substitutes for activities like diving, snorkeling, and fishing, and thus alleviating pressures on natural reef areas. Conservation strategies also include education and awareness campaigns and, occasionally, limitations on visitor access to coral reef sites in need of protection to allow for ecosystem conditions to recover from negative impacts.

With multiple strategies to consider, there is a need to understand the value of reef conservation via increasing coral reef cover (e.g., plantings), artificial reef creation, and reducing visitation at reef sites. Previous research suggests that restoring, conserving, or preventing further reef degradation provides economic value for reef users such as snorkelers, divers, and anglers. For example, in one of the first studies to examine the economic value of coral reef quality, Weilgus et al. [13] found that divers are willing to pay USD 2.60 per dive to improve coral and fish diversity at reef sites in the Red Sea. Thur and Parsons [14] estimated economic losses from reductions in coral cover, coral and fish diversity, and visibility at reef sites in Bonaire that ranged from USD 45 to 192 per diver/per year for moderate and severe damage, respectively. Gaskin [15] found that households in American Samoa were willing to pay about USD 15, USD 13, USD 10, and USD 17 annually to improve coral bleaching, coral diversity, coral rubble, and fish diversity, respectively, at reef sites in American Samoa. Previous research has also suggested that artificial reefs can generate socioeconomic benefits for coastal communities [16,17,18,19] and provide value to recreational users. For example, Johns et al. [20] estimated the value of maintaining artificial reefs in Florida for diving and fishing to be about USD 15 per person-day, and Milon [21] found that the value to visitors of creating new artificial reefs in Florida ranged from about USD 4 to 128 per year. Polak and Shashar [22] found that divers were willing to pay about 20 and 27 (in New Israeli Shekels) per year to improve species richness and species abundance at an artificial reef site in Israel. Finally, a number of studies have suggested that crowding in marine environments such as dive sites can diminish user experiences [23,24,25]. However, Schuhmann et al. [26] is the only study we found that estimated an economic value for reducing marine congestion at reef sites. This study found that divers in Barbados and Tobago were willing to pay about USD 4 per dive to reduce encounters with other divers.

Ultimately, the benefits of any restoration or conservation strategy are for people in the form of sustained or improved ecosystem services. Therefore, it is important for managers to understand economic values for reef restoration to help inform decision-making and serve as inputs into numerous analyses that are conducted in support of marine policy. Our study addresses this need by conducting a stated preference choice experiment survey to examine the way U.S. and Florida residents make economic trade-offs among different reef restoration strategies, including increasing coral reef cover, deploying artificial reefs, and limiting visitor access to coral reef sites. While previous research has shown that natural/coral and artificial reefs have economic value, most of these focus on user values such as those held by divers. Further, there is limited research that facilitates comparisons among coral restoration and conservation strategies and their outcomes. Our study achieves both of these by including potential users and non-users in our sampling frame and computing marginal rates of substitution between strategies. Overall, we believe our study delivers critical information on economic values associated with reef restoration and conservation that will facilitate prioritizing investments and developing optimal public policies.

2. Methods

2.1. Research Framework

In this research we use a stated preference choice experiment (SPCE) framework to understand economic values for goods and services that are not traded in traditional markets. Often these types of goods and services are referred to as non-market goods, and can include many environmental goods such as air and water quality, outdoor recreational opportunities, and conservation of resources such as reefs. It is important to note that in this research the term preferences refers to economic preferences, which consumer theory and welfare economics consider driving forces of individual’s choices. We acknowledge that critics have suggested a number of flaws with various tenets of welfare economics (see [27] for a review) but suggest that categorical dismissal of welfare economics is unwarranted [28]. In the following paragraphs we provide an overview of SPCEs, followed by a more detailed description as it applies to our research.

Consumer theory [29] provides the foundation for SPCEs. Consumer theory assumes that an individual’s utility for a good is a function of the good’s attributes. For example, utility for a car may depend on attributes such as gas mileage, make or model, seating capacity, engine type, price, etc. In choosing a car, individuals make trade-offs among the cars attributes in a way that maximizes their utility. For environmental applications, the non-market good is typically characterized by attributes of policy or management interest, and a survey instrument is used to provide basic information about the attributes of the good. A range of numeric or categorical levels is specified for each attribute, and experimental design plans are used to combine attributes and levels into different alternatives. In the SPCE survey, respondents are shown choice task questions that contain two or more alternatives (different bundles of attribute levels), and are asked to indicate which is their most (and sometimes least) preferred.

Our survey described alternatives for reef conservation using four attributes: (1) the change in live coral cover, (2) the change in number of visitors accessing coral reefs each year, (3) the change in number of artificial reefs, and (4) a fee to access coral reef areas. This fee would help pay for reef restoration. All changes are relative to the status quo in 2017.

Table 1. Attributes and levels used in Florida reef conservation choice experiment.

Attribute	% Change in Natural Reef Coral Coverage	% Change in Number of Reef Visitors	% Change in New Artificial Reef Locations	Access Fee for Natural Reefs (Cost per Visit)
Status Quo	There is 90% less coral cover than in the 1980s	There are over 3 million visitors to Florida reefs per year.	There are almost 700 artificial reefs in Southeast Florida.	Current access fees range from USD 2 to 15 per person.
Level 1	no change	no change	no change	no change
Level 2	10% more live coral cover	10% fewer visitors	5% increase in artificial reef sites	additional USD 5 fee per visit
Level 3	20% more live coral cover	15% fewer visitors	10% increase in artificial reef sites	additional USD 10 fee per visit
Level 4	30% more live coral cover		20% increase in artificial reef sites	additional USD 20 fee per visit
Level 5				additional USD 30 fee per visit

describes the choice experiment attributes and levels.

As the number of all possible combinations of attributes and levels is large, an experimental design plan was used to generate and select combinations of attributes and levels, and group these into alternatives, based on efficiency criteria. Our final experimental design plan consisted of 96 combinations of the attributes and levels (96 individual survey versions). These combinations were then blocked into 12 main survey versions, randomly distributed across respondents. Each survey respondent was shown eight pairs of alternatives, referred to as a choice task question, and asked to select their preferred alternative from each pair. An example of a choice task question is provided in Figure 2.

Random utility theory provides the econometric modeling framework for this research. The theory assumes that that utility ($U$) for a good consists of a systematic, known component ($V$) and a random component ($\epsilon$). For our research, coral restoration is the good and the utility that individual i receives from restoration in alternative a can be expressed as

$$U_{ia}=V_{ia}+{\epsilon }_{ia}$$

(1)

where $U_{ia}$ is the unobservable utility that i associates with a, $V_{ia}$ is the quantifiable, known portion of utility, and ${\epsilon }_{ia}$ is the random, unobservable effects associated with a for individual i. Alternative a can be decomposed into its specific attributes—change in coral cover, change in visitors, change in artificial reefs, and price—and the systematic component of utility $V_{ia}$ is then

$$V_{ia}={\beta X}_{ia}$$

(2)

where $X_{ia}$ is a vector of attributes and the associated levels for coral conservation alternative a and β are the attribute coefficients. Substituting the expression for $V_{ia}$, the utility function can be expressed as

$$U_{ia}={\beta X}_{ia}+{\epsilon }_{ia}$$

(3)

If individuals are assumed to be utility maximizers, the probability that an individual i will choose alternative a from a set of C alternatives is equal to the probability that the utility derived from a is greater than the utility derived from any other alternative in the choice set C, expressed as

$$\begin{gathered} \mathrm{Pr}\left(i chooses a from C\right)=\mathrm{Pr}(U_{ia} >U_{ij}) for all j \in C \\ =\mathrm{Pr}\left(V_{ia}+{\epsilon }_{ia}>V_{ij}+{\epsilon }_{ij}\right)for all j \in C \\ =\mathrm{Pr}({\beta X}_{ia}+{\epsilon }_{ia}>{\beta X}_{ij }+{\epsilon }_{ij }) for all j ϵ C \end{gathered}$$

(4)

Assuming a type I extreme value distribution for the error component (a common assumption for discrete choice models; [30]), (4) is operationalized as

$$\mathrm{Pr}\left(i chooses a\right)=\mathrm{e}\mathrm{x}\mathrm{p}(\beta X_{ia})/\sum _{j=1}^J\exp (\beta X_{ij})$$

(5)

Ordering the observations such that the first n₁ individuals chose alternative a, the next n₂ individuals chose alternative b, and so on, for all elements j in choice set C, the likelihood function for (5) can be expressed as

$$L=\prod _{i=1}^{n1}{P}_{1i}\sum _{i=nl+i}^{nl+n2}{P}_{2i}\dots \dots \prod _{i=I-nj+1}^I{P}_{ji}$$

(6)

which simplifies to

$$L=\prod _{i=1}^I\prod _{j=1}^{J}ln{P}_{ij}^{fij}$$

(7)

Defining a dummy variable f_ij, where f_ij = 1 when alternative j is chosen and f_ij = 0 otherwise, the function can be can be written as

$$L^{*}=\sum _{i=1}^I\sum _{j=1}^J{f}_{ij}\mathit{ln}{P}_{ij}$$

(8)

Replacing P_ij with Equation (5), the elements of $\beta$ can be recovered through maximum likelihood techniques.

2.2. Survey Development and Implementation

The survey instrument was developed using two focus group discussions with South Florida residents during September 2018. These groups were followed by discussions with key partners in the National Oceanic and Atmospheric Administration (NOAA) Coral Reef Conservation Program (CRCP), including staff from Florida Fish and Wildlife Conservation Commission (FWC), Southeast Florida counties government entities, and Florida Department of Environmental Protection (FDEP). The latter discussions were held to ensure the attributes and levels were within the bounds of realistic conservation and restoration strategies. The survey was pre-tested using 25 in-person interviews to confirm the survey length and for quality control testing.

The final survey instrument first provided basic information about Florida reefs followed by questions about respondent’s general knowledge of coral reefs, visitation to and use of natural and artificial reefs, the importance placed on reefs, satisfaction with reef management, perceptions of marine resource conditions and threats, and beliefs about stewardship and management of reefs. The survey concluded with the choice experiment. As stated above, each respondent was given eight choice task questions, with each question asking them to select their preferred scenario from two different reef conservation scenarios. The survey was programmed in English and Spanish and implemented using an online survey platform administered by Ipsos Global Market Research.

The final survey was fielded between 18 May 2021 and 13 June 2021 using the Ipsos KnowledgePanel. A total sample size of approximately 1600 completed surveys was desired; however, to accommodate several specific analyses (not reported here) residents of Southeast Florida (Broward, Martin, Miami-Dade, Monroe, and Palm Beach Counties) and Florida residents were oversampled (see [1] for a detailed description of the sampling design). Sampling began with an initial email invitation that included a link to the survey. This invitation was sent to 3176 panel members 18 years or older, using a stratified random sample approach. Email reminders were sent to non-responders three days after the initial email, with additional reminders sent to the remaining non-responders on Days 10 and 16 of the field-period. A total of 1635 respondents completed the survey, resulting in a 52% response rate. The mean age of respondents was 50.6 years, and about 53% of respondents were female (47% male), 56% of respondents were white, 25% Hispanic, and 13% black. About 61% of respondents had obtained some college education and the median annual household income category was USD 50,000–74,999.

3. Results

3.1. Beliefs About Florida Coral Reefs and Attitudes Toward Conservation

Respondents were somewhat knowledgeable about the topic of coral reefs in general, with 54% stating they knew a little about the topic and 26% stating they knew a moderate amount or a great deal. Similarly, about 42% of respondents felt they knew a little about the current condition of Southeast Florida reefs, while fewer (18%) felt they knew a moderate amount or a great deal about this topic’s questions. (The sub-samples of respondents from Southeast Florida counties and the state of Florida had considerably higher knowledge levels about reef conditions than the sample as a whole.) Although a relatively small percentage of respondents believe they have moderate or a great deal of general knowledge about Florida reefs, over 80% felt that coral reefs are part of what makes Southeast Florida special and over 90% said it is very important to protect coral reefs for future generations. With regard to artificial reefs, about 42% of respondents felt they knew a little about the differences between coral and artificial reefs, and about a third of respondents (34%) said they knew a moderate amount or a great deal about the topic. Just over half of respondents (52%) felt it is very important to have artificial reefs in Southeast Florida and about 64% stated that artificial reefs can allow more people to visit reefs in Florida.

Respondents were asked about their perceptions of various threats to Florida’s coral reefs, including overfishing, climate change, water pollution, and recreation and tourism. About 67% of respondents believe that water pollution is a significant threat, followed by climate change (52%), overfishing (39%), and recreation and tourism (26%). With regard to attitudes about reef conservation strategies, 75% of respondents agreed that the construction of artificial reefs can help offset the loss of natural reefs, 81% agree that governments have the right to intervene to protect reefs from negative human impacts, and about 67% believe that the government has the right to restrict public access to reefs for conservation purposes. In addition, 67% and 57% of respondents stated that scientific research and coral reef education in K-12 are important for conservation.

Prior to the choice experiment, respondents were asked about their willingness to pay a site access fee for coral and artificial reefs to help improve reefs. Fees were described as parking, marina, and charter boat fees that would be added to existing costs (e.g., an added fee to charter boat trip cost). Respondents indicated the amount they would pay using a sliding scale of USD 1 to 50; they also had the option to opt out and not pay an additional fee to access the site. Approximately 70% and 60% of respondents stated they would pay a fee to access coral and artificial reef sites, respectively, with the median payment being USD 10 for coral and USD 5 for artificial reef sites.

3.2. Stated Preference Choice Experiment

As noted previously, each respondent was given eight choice task questions for the choice experiment component of the survey. Over all of the choice task questions, item non-response was approximately 6% and varied between 5% and 6% for each question, resulting in a final dataset for choice model estimation of 12,335 observations. Over all of the choice task questions, the first scenario, Option A, was selected about 53% of the time and the second scenario, Option B, was selected about 47% of the time.

The attributes in the choice model include “percent increase in natural coral cover,” “percent decrease in visitors to reef”, “percent increase in number of artificial reef sites”, and “access fee”, which serves as the individual’s budget constraint. Attribute parameters are estimated using maximum likelihood and a conditional logit specification, as in Equation (8) using Nlogit Version 6 Econometric Software. Willingness-to-pay, calculated as compensating variation, was calculated from model parameters following standard formulas [31]. Model results and WTP are shown in

Table 2. Choice model results.

Attribute	Coefficient	Standard Error	95% Confidence Interval	WTP for 1% Change in Attribute
% Increase in natural coral cover	0.05070 **	0.00173	0.04731–0.05408	$14.92
% Increase in number of artificial reef sites	0.02582 **	0.00201	0.02188–0.02976	$7.60
% Decrease in visitors to reef	0.02118 **	0.00254	0.01620–0.02617	$6.23
Cost of fee	−0.00340 *	0.00134	−0.00603–−0.00076

* p < 0.05; ** p < 0.01.

. Results confirm ex ante hypotheses that increasing natural reef cover, increasing the number of artificial reef sites, and decreasing visitors, which can be interpreted as decreasing congestion at the site, are statistically significant. All strategies have a positive sign and are utility-enhancing. The cost constraint is negative and significant, as expected. Results demonstrate that increasing natural coral cover is significantly more valuable to respondents than adding artificial reef sites or decreasing congestion, though the latter strategies are still economically valuable.

In addition, the way in which respondents make economic trade-offs among the attributes, referred to as the marginal rate of substitution, are calculated as the attribute parameter ratios. Stated another way, the marginal rate of substitution between natural and artificial reefs expresses the increase in the number of artificial reef sites needed to leave a respondent indifferent between that and a 1% increase in natural coral cover. These marginal rates of substitution are shown in

Table 3. Marginal rates of substitution between conservation strategies.

Marginal Rates of Substitution	%
Percent increase in number of artificial reef sites needed to equal a 1% increase in natural coral cover	1.96
Percent decrease in number of visitors needed to equal a 1% increase in natural coral cover	2.40
Percent decrease in number of visitors needed to equal a 1% increase in number of artificial reefs	1.22

.

3.3. Conservation and Restoration Scenario Analyses

The results from the choice model can be used to examine the welfare effects of various conservation and restoration scenarios that involve changes to visitation and artificial and natural coral reefs. Scenario analyses involve simulating the model using potential management options, for example, the level of natural coral restoration described in Mission: Iconic Reefs. Conservatively, scenario analyses should use attribute levels that are in the general range of the experimental design, i.e., an increase in natural coral cover should not go considerably higher than 30% (the highest experimental design level for that attribute). Below we discuss three types of scenarios: (1) for very small changes, how much can a fee increase without causing disutility (negative welfare), (2) what are the welfare gains (value) from the proposed restoration levels outlined in Mission: Iconic Reefs, and (3) which combinations of conservation and restoration strategies result in the same amount of value?

3.3.1. Small Changes

These analyses assume very small increases to natural coral restoration and artificial reefs, and very small decreases to visitation. The model is simulated to determine how much a fee can increase before survey respondents experience negative utility, considered to be a welfare loss. The first scenario involves increasing both natural and artificial reefs by 1% and decreasing visitation by 1%. Results indicate that survey respondents are willing to pay an increase in entry fees up to about USD 28; fees above this amount result in negative utility and imply that respondents have reached their budget constraint. We expect larger increases in natural and artificial reefs would support larger fee increases, and simulate a scenario that includes a 2% increase in natural and artificial reefs and a 1% decrease to visitation. Results indicate that a fee could be no higher than USD 51 before a welfare loss is incurred. These analyses can be informative when resources for reef conservation are limited and managers consider raising or introducing entry fees as a mechanism to generate funds.

3.3.2. Mission: Iconic Reefs

Mission: Iconic Reefs (MIR) is a coral restoration strategy developed by NOAA and other partners to restore seven reef sites within the Florida Keys National Marine Sanctuary in Southeast Florida. The goal of MIR is to restore the amount of stony coral cover within the reef sites to 25%. Phase I of MIR will restore sites to 15% stony coral cover, with Phase II restoring the additional 10%, to total 25% at the end of both phases. Both phases will restore Elkhorn, Brain, Pillar, and Staghorn corals and the second phase will add finger and blade corals. In this analysis, the model is used to determine the value of each phase of MIR. To illustrate only the value of MIR, we assume that there are no changes to the number of artificial reef sites nor visitation. Results demonstrate that the value to survey respondents of MIR Phase I is approximately USD 224, and the additional value added from Phase II is USD 148.

3.3.3. Similar Welfare Gains

The marginal rates of substitution in Table 3 demonstrate that, all else equal, increasing natural coral cover provides nearly twice as much utility as increasing the number of artificial reefs, and close to two and a half times the utility as decreasing visitation. It may also be informative for managers to understand what mix of all strategies result in about the same amount of value to respondents but involve different combinations of attribute changes. This can help determine efficient and cost-effective strategy mixes. In these analyses, we simulate the model to determine management scenarios that result in the same benefit, or willingness to pay, but involve different combinations of attribute changes (

Table 4. Attribute combinations that produce similar benefits.

Willingness to Pay (Benefit)	Scenarios
USD 53 USD 51 USD 51	(a) 1% increase in natural coral; 1% increase in artificial reefs; 5% decrease in visitation (b) 2.5% increase in natural coral; 1% increase in artificial reefs; 1% decrease in visitation (c) 1% increase in natural coral; 4% increase in artificial reefs; 1% decrease in visitation
USD 101 USD 102 USD 99	(a) 2% increase in natural coral; 2% increase in artificial reefs; 9% decrease in visitation (b) 5% increase in natural coral; 2% increase in artificial reefs; 2% decrease in visitation (c) 2% increase in natural coral; 7.5% increase in artificial reefs; 2% decrease in visitation
USD 150 USD 154 USD 152	(a) 2% increase in natural coral; 2% increase in artificial reefs; 17% decrease in visitation (b) 8.5% increase in natural coral; 2% increase in artificial reefs; 2% decrease in visitation (c) 2% increase in natural coral; 14.5% increase in artificial reefs; 2% decrease in visitation

). In Table 4, each scenario (a) changes visitation, each scenario (b) changes natural coral cover, and each scenario (c) changes artificial reefs.

4. Discussion

The main goal of this study was to examine economic values for coral restoration and conservation strategies. This study also examined public knowledge about coral reefs, beliefs about coral reef conditions, and attitudes toward conservation. The results indicate that, despite low overall knowledge about coral reefs, there is strong consensus among respondents on the importance of coral reefs to Florida’s identity (80%) and the need to protect them for future generations (90%). This suggests that coral reefs exhibit existence value and that strategies that restore coral reefs to their natural state would garner support. Alternatively, 75% of respondents believe that constructing artificial reefs can help offset the loss of natural reefs and 67% believe the government has the right to restrict public access to reefs for conservation. In general, these results suggest people have a stronger affinity for access to natural coral reefs compared to artificial reefs. While artificial reefs are relatively less preferred, people still benefit from these structures and believe they are important to have in Florida. These attitudes may depend on the types of recreation experiences people seek and the trade-offs they are willing to make for those experiences.

The stated preference choice experiment demonstrates that respondents are willing to pay USD 14.92 for every 1% increase in natural coral cover, USD 7.60 for every 1% increase in the number of artificial reef sites, and USD 6.23 for every 1% decrease in congestion at a reef site. These results suggest stronger economic preferences for natural coral reefs, but artificial reefs could be used as alternative site destinations or substitutes. This information may help when prioritizing general marine management goals, and may help determine which reef conservation efforts will be most supported by the public. The results suggest general support for programs such as Mission: Iconic Reefs, but also outline different mixes of conservation efforts that would provide similar benefits. Hypothetically, the (c) scenarios in Table 4 would be preferable if increasing natural coral cover is more costly than increasing the number of artificial reefs.

Though we have limited the discussion in this paper to benefits and value, we recognize that for our results to be most useful, the cost of various conservation efforts should be considered. This proves somewhat difficult, as the cost of reef conservation activities varies widely and it is often difficult to parse out costs of specific strategies from larger program and/or project budgets. One study that synthesized coral restoration costs across global sites suggests a range from 6000 USD/ha for the nursery phase of coral gardening, to 4,000,000 USD/ha for substrate addition to build an artificial reef [32], with the median cost across all studies being 400,000 USD/ha (figures in 2010 USD). In the Florida Keys, the average cost per coral restored through Mission: Iconic Reefs is USD 259, with a total estimated cost of about USD 61 million for the coral restoration alone, though this excludes costs for site preparation, monitoring, and maintenance. If we apply our choice experiment results to Southeast Florida households, the total value of a 1% increase in natural coral cover is approximately USD 35 million. Although our study is national in scope, and therefore could result in larger values if applied to national households, we caution against doing so as we do not formally examine the spatial extent of the market for Florida coral restoration. Such an analysis would be important before conducting any cost–benefit analyses, and we suggest this as an area for future analysis.

We acknowledge several limitations of the study. For example, this study does not differentiate between coral species when describing the increase in natural coral cover. It is possible that people may have distinct preferences for different types of corals, particularly as some species, i.e., Elkhorn coral, are classified as threatened or endangered. Previous studies by Wallmo and Lew [33] have demonstrated non-use benefits for recovering Elkhorn coral of approximately USD 72 per US household. This and other values such as provisioning values for flood and erosion protection may (or may not) be a component of the values reported here; we did not specifically question respondents concerning the benefits they personally confer on natural coral or artificial reefs. In addition, the survey, which was designed in consultation with Florida state agencies, focused on management strategies that increase coral cover, deploy artificial reefs, or limit visitor access. However, there are other factors, such as fishing restrictions and water quality efforts, that may also influence restoration values and could be examined in future surveys.

We also recognize that the payment vehicle used in this study—a site access fee—may not be binding to all respondents, as some respondents may assume they simply would not incur the fee as they do not visit reef sites in Florida. Access fees are a common payment vehicle for studies that involve users of a resource; however, in retrospect a payment vehicle that is binding on all respondents, such as a tax, would have been preferable. Additionally, the experimental design was computed specifically for the attributes and levels described and a linear model. This assumes that there are no diminishing returns to any attribute, e.g., restoring natural coral cover from 24 to 25% provides the same utility as restoring cover from 3 to 4%, and this may be unlikely. Adding a squared term to the natural coral cover and artificial reef attributes would allow us to investigate non-linear preference functions, but the experimental design would likely not support this model specification.

Finally, we note that this study estimates the value of reef conservation, and not the economic impacts that arise from expenditures associated with coral and artificial reefs (e.g., expenditures on dive charters may enhance local economies via jobs and sales revenues). Prior studies examining the economic impacts of Southeast Florida coral reefs have shown that trip-based expenditures on recreational fishing generated an economic output of USD 384 million, and expenditures on recreational diving and snorkeling in coral reefs generated USD 902 million in economic impacts [34,35].

5. Conclusions

Florida’s coral reefs provide valuable ecosystem services but are under threat from various pressures. In order to maintain coral reef benefits and mitigate pressures, conservation and restoration are needed. However, an understanding of specific values for reef restoration and enhancement is needed to inform decision-making and support marine policy. This study conducted a stated preference choice experiment survey to examine the way U.S. residents make economic trade-offs among different restoration strategies, including increasing coral cover, deploying artificial reefs, and limiting visitor access to reef sites. High values for natural coral reefs suggest that management approaches to restoring coral populations, such as the use of coral nurseries and out-planting corals, are strategies to prioritize. Other strategies such as deploying artificial reefs or restricting public access are less preferable but may be used as alternatives. The implications may be especially relevant to issues of reef use, visitation rates, and the carrying capacity of reef sites. Natural and artificial reefs used as substitute goods may help distribute human activity and pressure. For instance, artificial reefs placed adjacent to an existing natural reef may shift diving activity away from natural reefs (Leeworthy, et al., 2006). On the other hand, they may be complementary, as an enhanced artificial reef system could attract more divers to the area, potentially increasing visits to natural reefs as well. Further considerations for targeted communication and outreach may be necessary to promote awareness and responsible behaviors that help prevent damage to coral reefs. Overall, the results of this study provide essential information to policy analysts concerning reef use, reef importance, and economic values for reef restoration. This information is critical. These results can ultimately support conservation efforts for natural and artificial reef systems and guide management strategies that best serve the interests of Southeast Florida’s residents and visitors.