Taxonomic and functional diversity increase the aesthetic value of coralligenous reefs

Abstract

The aesthetic value of landscapes contributes to human well-being. However, studies which have investigated the link between biodiversity and ecosystem services have not taken aesthetic value into account. In this study we evaluated how the aesthetics of coralligenous reefs, a key marine ecosystem in the Mediterranean, is perceived by the general public and how aesthetic preferences are related to biodiversity facets (taxonomic, phylogenetic and functional diversities). We performed both biodiversity measures and online-surveys of aesthetic perception on photographic quadrats sampled along the French Mediterranean coast. Our results show that species richness and functional richness have a significant positive effect on aesthetic value. Most of the ecological literature, exploring the relationship between biodiversity and ecosystem functioning and service has focused so far on 'economical' aspects of biodiversity (provision or regulation). Our results illustrate that cultural facets, such as 'beauty', should also be central in our motivations to preserve ecological diversity.

Figure 1

(a) Coralligenous assemblage in the Mediterranean. Copyright: Laurent Ballesta for Andromède Océanologie/Agence de l’eau RMC: Campagne RECOR 2011. Photograph taken by Laurent Ballesta. (b) Map of the 113 stations sampled in the French Mediterranean. Stations ranged from −20 to −90 m deep. Each station was sampled by three photographic quadrats taken at the same depth. Map generated by using R 3.2.4 2016-03-10 (R: A Language and Environment for Statistical Computing, R Core Team, R Foundation for Statistical Computing, Vienna, Austria (2016) https://www.R-project.org), created by Florian Holon for Andromède Océanologie/Agence de l’Eau RMC.

Figure 2

(a) Correlation coefficients between the aesthetic scores of photos and diversity indices (n = 1260). Nbsp: number of species. PD: Phylogenetic diversity. FRic: standardized Functional Richness. FEve: Functional evenness. FDiv: Functional divergence. Linear model was not performed for FEve and FDiv because their correlations with aesthetic scores were not significant. Bold values: significant p-values. R² = correlation coefficient. Bonferroni correction = adjusted p-values after a Bonferroni correction. (b) Relationship between aesthetic scores and diversity indices. n = 1260. (i) Linear model for aesthetic scores as a function of the number of species per quadrat. R² = 0.132. (ii) Linear model for aesthetic scores as a function of taxonomic diversity measured using Shannon’s index (expressed as equivalent number of species). R² = 0.140. Linear model for aesthetic scores as a function of Simpson’s index is not presented because the relationship is not better than with Shannon’s index. R² = 0.164. (iii) Linear model for aesthetic scores as a function of standardized FRic. R² = 0.057. (iv) Linear model for aesthetic scores as a function of PD. R² = 0.073.

Figure 3

Relationship between observed coverages and preferred frequencies for (a) colours and (b) species groups. The vertical axis represents the preferred total frequencies and the horizontal axis represents the observed total coverages. Black lines represent the bisectors. N = 338 quadrats. Pictograms provided by DORIS http://doris.ffessm.fr.

Figure 4. Description of the online questionnaire completed by 1260 persons.

(a) Among the 338 photos, a randomised selection of 15 pairs of photos was presented to the observer. For each pair of photos, they had to choose the photo they felt was the most beautiful. Here we present the photos that were considered to be the least aesthetic (left) and the most aesthetic (right). Photographs taken by Florian Holon. (b) Among the 15 photos chosen, 3 photos were presented again and the observer had to answer questions based on semantic scales. Questions were related to visual features such as colours, colourimetry, elements or species; and their feelings and emotions experienced during the observation. (c) Details on their social background were also collected.

Figure 5. Mapping the different facets of coralligenous assemblages biodiversity along the French Mediterranean coast.

(a) Stations (N = 113) mapped according to their aesthetic values. Each station represents the mean aesthetic score of three quadrats, scaled between 0 and 1. (b) Stations (N = 113) mapped according to their Shannon index values. Each station represents the mean Shannon index value of three quadrats, scaled between 0 and 1. (c) Stations (N = 113) mapped according to their FRic values. Each station represents the mean FRic value of three quadrats, scaled between 0 and 1. For all maps, areas were obtained using the kriging method (estimation of values between two stations).