combining geomorphologic, biological and accessibility values for marine natural heritage evaluation...

Combining geomorphologic, biological and accessibility values formarine natural heritage evaluation and conservation

ALESSIO ROVEREa,b,*, VALERIANO PARRAVICINIa,b, MARCO FIRPOa, CARLA MORRIa andCARLO NIKE BIANCHIa

aDipTeRis, Dipartimento per lo studio del Territorio e delle sue Risorse, Università degli Studi di Genova, Corso Europa 26, 16132Genova, Italy

bSEAMap srl, Via Greto di Cornigliano 6R, 16152 Genova, Italy

ABSTRACT

1. Natural heritage is the complex of geomorphologic and biological elements worthy of conservation.2. Especially in the marine environment, conservation effort is often focused on the biological elements only,

while multi-disciplinary approaches, including abiotic elements and social issues, are needed.3. A procedure to evaluate the Marine Natural Heritage (MNH) as a whole, integrating geomorphology and

biology, was tested in two coastal areas in the Ligurian Sea (NW Mediterranean): Punta Manara, a EuropeanSite of Community Interest (SCI), and Finale – Vado Ligure (non-SCI). In each area, scuba surveys werecarried out at six sites to categorize subtidal landforms and habitats, and these were then used as evaluationunits for assigning scores to subcategories of both geomorphological (Integrity, Representativeness, Rarity,Paleogeographic, Aesthetic) and biological (Naturalness, Vulnerability, Rarity, Economic, Aesthetic) categories.

4. Four sites in the area of Punta Manara obtained high scores, thus fully justifying the special managementmeasures required for SCI implementation. However, two sites in the Finale – Vado Ligure area exhibitedbiological heritage values higher than those of Punta Manara, while a third site exhibited values comparablewith those of Punta Manara when considering both biology and geomorphology. This highlighted the presenceof features worth conserving also in non-SIC situations.

5. Accessibility to scuba divers was evaluated by means of a simple scheme, and added information on theperception of MNH in the study sites.

6. It is suggested that the evaluation system may be used, with appropriate benchmarking, in other areas for theselection of sites proposed for legal protection or special management measures, based on their natural heritagevalues.Copyright # 2011 John Wiley & Sons, Ltd.

Received 18 December 2010; Revised 6 July 2011; Accepted 24 July 2011

KEY WORDS: coastal; sublittoral; landscape; habitat management; benthos

INTRODUCTION

One of the main goals of nature conservation sciences is toprovide tools to quantify the value and to assess theeffectiveness of preservation measures of natural heritage,which is defined as a complex of geomorphological andbiological elements of nature sustaining life (UNESCO, 1972).Early attempts in the Mediterranean Sea (Bianchi and Zurlini,1984; Bianchi and Zattera, 1986), coined the term ‘ecotypologies’for the classification of marine environments contextually based

on both geomorphological and biological features. In recentyears, natural heritage evaluation and management haveassumed a growing importance (Brilha, 2002), resulting in effortsto protect not only species and habitats, but also relevantgeomorphologic features (Reynard, 2004; Panizza, 2009). Thistwofold perspective (i.e. conservation of both biological andgeomorphological heritage) is also recommended by internationallegislation, notably by the EU Directive 92/43 (Council Directive92/43/EEC of 21 May 1992 on the conservation of naturalhabitats and of wild fauna and flora). Multi-disciplinary

*Correspondence to: A. Rovere, DipTeRis, Università di Genova, Corso Europa 26, 16132 Genova, Italy. Email: [email protected]

Copyright # 2011 John Wiley & Sons, Ltd.

AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS

Aquatic Conserv: Mar. Freshw. Ecosyst. 21: 541–552 (2011)

Published online in Wiley Online Library(wileyonlinelibrary.com). DOI: 10.1002/aqc.1214

approaches are therefore a major goal for management andconservation in both terrestrial and marine ecosystems (Mackeyet al., 2001; Munné et al., 2003; Bianchi et al., 2004b; Parraviciniet al., 2006; Rovere et al., 2006; Urban and Daniels, 2006;UNESCO, 2008; Burlando et al., 2010).

Scoring systems to identify natural heritage values are anessential tool for scientists to inform policy-makers on theconservation efforts they must sustain for the territory theyare entrusted by society to manage (Hiscock et al., 2003).Indices for providing decision support mechanisms toenvironmental management are largely used on land (e.g. firerisk or habitat quality evaluation), and have gained newinputs from the development of modern remote sensing andGeographic Information Systems techniques (Qi et al., 1994;Munnè et al., 2003; Gitelson, 2004; Iliadis, 2005;Montefalcone et al., In press ). Nevertheless, the identificationof ‘measures of quality, and the recommendation of indicatorsto underpin implementation of directives, conventions,statutes and other more informal national and internationalinitiatives’ (Hiscock et al., 2003) remains a challengingapproach in the sea.

For those aiming at the evaluation and management of theMarine Natural Heritage (hereafter MNH), the transfer of‘terrestrial-born’ indices, scoring systems and algorithms tothe marine environment needs a heuristic approach. Thedifficulty does not lie in the application of those formulaicarrays to marine features, but rather in the collection of thebasic information in the sea. The most evident obstacles to befaced are operational, administrative and conceptual (Bianchi,2007). Operational difficulties, especially in the subtidal zone,are the complex logistics of fieldwork to gather reliable datato insert in the scoring process (Downie, 1999). Anyinformation obtained at sea has therefore a much greater costthan the same on land (e.g. seafloor vs land mapping andcover assessment), and this is in large part the reason for thedearth of information on marine environments in comparisonwith terrestrial ones. Administrative obstacles reside in thedifficulty for administrators and policy managers to conceivethe marine environment as ’territory’, notwithstanding themultiple human uses of it (Bianchi et al., 2004a). Especially incoastal waters, the coexistence of fishery and harvesting ofliving resources, extraction of abiotic resources, sewagedischarge, development of infrastructures, navigation, andrecreational activities (tourism, pleasure boating, bathing,diving, etc.) requires planning and management that can becompared with those implemented on land. Conceptualdifficulties are linked to the lack of visual perception of thesubmerged seascape and to its low accessibility (Bianchi et al.,2005), which hamper the application to the marineenvironment of approaches typical of terrestrial landscapeecology (Cocito et al., 1991).

Although schemes do exist for scoring different parts ofMNH, most approaches encompass biological features(Bellan-Santini et al., 2002; Diaz et al., 2004; Bianchi et al.,2008; Edgar et al., 2008) but neglect geomorphological ones.Thus, virtually all approaches to marine conservation dealwith biological heritage only (Diaz et al., 2004; Derous et al.,2007) and often provide only semi-quantitative means toassess it (e.g. UNEP-MAP, 1998; OSPAR, 2006). Forexample, evaluation schemes taking into account the degreeof naturalness, vulnerability, rarity, economic and aestheticvalues have been developed for Mediterranean Sea habitats

(UNEP-MAP, 1998; Relini, 2000), and can therefore beapplied to marine management (Bianchi, 2007). Abioticfeatures are incorporated in the schemes for assessing theconservation importance of underwater locations in the UK(Hiscock, 2008) as they fall into the definition of ‘seascapes,habitats and species for which we have a special responsibilityin a national, regional or global context’ (Connor et al.,2002), but the evaluation of their importance is still far fromthat given to biotic features. Specific evaluation schemes forsubmerged landforms are seldom, if ever, reported in theliterature. This gap has been partially filled by recent studiestranslating to the sea the terrestrial concepts of geoheritage(Orrù et al., 2005; Zouros, 2007; Rovere et al., 2010, 2011a),and by schemes addressing underwater seascapes, in additionto marine habitats and species, such as the Mediterranean‘Livre Rouge Gérard Vuignier’ (Boudouresque et al., 1990) orthe UK ‘Nationally Important Marine Features’ (Connoret al., 2002). Nevertheless, procedures for the evaluation ofMNH as a whole are still lacking.

In this paper a methodology is proposed to score marinesites, addressing both biological and geomorphological values,and to combine them in a single graphical representation for asynoptic view. In addition, we also scored accessibility:although not directly linked with MNH evaluation, this is animportant information for management purposes, as moreinaccessible sites are intrinsically less exposed to humanpressures than easily accessed ones. We tested our method intwo areas of Liguria, an administrative region of Italy, subjectto different management regimes, to explore to what extentthe existing approaches to marine conservation are consistentwith a quantitative assessment of MNH as a whole.

METHODS

Study areas

Liguria has an arch-shaped mountain territory with a steepseaward slope (Rovere et al., 2011b), which dictates most ofthe characteristics of the Ligurian Sea shelf (Cattaneo Viettiet al., 2010). The two test areas selected (Figure 1) are PuntaManara, which consists of a single rocky headland (a), andFinale – Vado Ligure, which includes three rocky headlandsnamed Punta Crena (b), Capo Noli (c) and Capo Vado (d).

Punta Manara is located about 46 km east of Genoa, thecapital city of Liguria. It is predominantly characterized bysandstone cliffs and coastal rockfalls extending into theshallow marine environment (Rovere et al., 2006). A meadowof the seagrass Posidonia oceanica is located on the easternside of the headland, while coralligenous reefs (i.e. corallinealgae build-ups with a diverse associated biota) havedeveloped on rocky shoals at some distance from it (Morriet al., 1986). Both P. oceanica meadows and coralligenousreefs are listed in the Annex I of the EU Directive 92/43(Habitats Directive), which has resulted in part of the PuntaManara sea floor being identified as a European Union Siteof Community Importance (Figure 2(a)).

Finale – Vado Ligure area is located 48 to 57 km west ofGenoa. Its coastline is composed of alternating pocketbeaches and rocky coasts of limestone and schist, such asthose of Punta Crena (Figure 2b), Capo Noli (Figure 2c) andCapo Vado (Figure 2d), in front of which sparse rocky shoals

A. ROVERE ET AL.542

Copyright # 2011 John Wiley & Sons, Ltd. Aquatic Conserv: Mar. Freshw. Ecosyst. 21: 541–552 (2011)

are located (Rovere et al., 2011b). Although portions of thesubmerged part of this area have been reported as ofenvironmental value because of the occurrence of P. oceanicameadows and coralligenous reefs (RaMoGe, 2000; Rovereet al., 2006; Diviacco and Coppo, 2007), no comprehensiveenvironmental studies have been carried out, and no specialmanagement measures are envisaged.

Surveys

In both areas, six sites were selected at various depths anddistances from shore in order to provide an as representative

as possible picture of the whole area (Figure 2): sites A, B, C,D, E and F were located in the Punta Manara area (a),whereas in the Finale - Vado Ligure area site H was off PuntaCrena (b), G and I were off Capo Noli (c), and J, K and Lwere off Capo Vado (d). Data were collected by scubasurveys, planned on the basis of aerial photography, sidescansonar and multibeam data from the Liguria RegionAuthority, and from the literature.

Sites were investigated using marked lines laid on thebottom as either depth transects (Bianchi et al., 2004a) ordeployed as polygonals to follow closed perimeters(Colantoni, 2007). Geomorphological and biological data

Figure 1. Location of the study areas in Liguria (NW Italy): (a) Punta Manara area; (b, c, d) Finale-Vado Ligure area (Figure 2).

Figure 2. Sites (in capital letters) where surveys have been done in the Punta Manara (a) and Finale – Vado Ligure (b, c and d) areas.

MARINE NATURAL HERITAGE EVALUATION AND CONSERVATION 543


were collected by visual inspections and recorded directlyunderwater on diving slates. Results were summarized usingblock diagrams and schematic profiles. Evidence of humanimpacts (e.g. lost artefacts on the sea floor) was also recordedas a help to judge environmental status. Habitats wereidentified based on conspicuous species and generalappearance (Morri et al., 2004) and named according to theclassification by the European Union Nature InformationSystem EUNIS (Tunesi et al., 2006).

Evaluation scheme

MNH has been split into two categories: geomorphological andbiological, each divided into subcategories (Table 1). The

evaluation of geomorphological heritage used the mostsignificant subcategories among those proposed by Reynardet al. (2007): Integrity (INT), Representativeness (REP),Rarity (RARgeo), Paleogeographic interest (PAL), andAesthetic value (AESTgeo). The evaluation of biologicalheritage adopted the UNEP-MAP (1998) scheme, whichrecognizes the subcategories Naturalness (NAT), Vulnerability(VULN), Rarity (RARbio), Economic importance (ECON),and Aesthetic value (AESTbio).

Landforms were chosen as the fundamental evaluation unitsfor geomorphological heritage, and habitats for the biologicalone. An evaluation unit is a portion of territory consideredhomogeneous in the scoring process. Scores ranging from 1 to3 (Table 1) were assigned for each subcategory to each

Table 1. Criteria adopted to define and scores assigned to calculate Geological Heritage (GeoH), Biological Heritage (BioH) and Accessibility indices

Criteria for GeoH evaluation

GeoH= (INT�REP�RARgeo�PAL�AESTgeo)� 3-4

INT: Integrity. State of conservation of a given landform. Scoring: 1= landform affected by either natural or human factors; 2= landform damaged inless than 50% of its surface; 3= landform in its natural status or poorly damaged in limited sites.

REP: Representativeness. Exemplarity of a given landform. Scoring: 1=process or landform not easily recognizable; 2=process or landform clearlyidentifiable in some parts; 3=process or landform easily recognizable (also to non-experts).

RARgeo: Rarity (geological acceptation). Rarity of a given landform at national, international or global level. Scoring: 1=commonly present in coastalor underwater areas; 2= few similar features at regional scale; 3= few similar features at national scale.

PAL: Paleogeographic interest. Importance of a given landform in defining processes or environments that have characterized the Earth history.Scoring: 1=absent; 2= landform provides some clue about tectonic/geologic history of the area; 3= landform provides the key evidence forcharacterising parts of tectonic/geologic history of the area.

AESTgeo: Aesthetic value (geological acceptation). The value of the landform in terms of emotional impact on users, partially following and adaptingthe schemes proposed by Reynard et al. (2007). The following formula was applied: AESTgeo= (Ver�Str)� 3-2, where Ver is the contribution ofthe landform to the verticality of the landscape; Str the presence of three-dimensional structures in the landform (e.g. caves, overhangs). Each valuewas assigned a score from 1 to 3, so the AESTgeo subcategory could vary between 1/9 and 1.Final scoring: 1= 1/9<AESTgeo≤ 1/3; 2=

1/3<AESTgeo≤ 2/3; 3=2/3<AESTgeo≤ 1.

Criteria for BioH evaluation (from UNEP-MAP, 1998)

BioH= (NAT�VULN�RARbio�ECON�AESTbio)� 3-4

NAT: Naturalness. (Heritage Value in UNEP-MAP 1998) Appraisal of the value of a given habitat for the national or regional natural heritage due toits unique character, because of the presence of endemism, exceptional structure (cliff, cave, platform), peculiar ecological situation (meeting of twowater masses, concentration zone) or because of symbolic and cultural value. Scoring: 1=none of the above feature present; 2=at least one of theabove features present; 3= two or more of the above features present.

VULN: Vulnerability. Inability of the habitat to maintain its structure and functions when faced with unfavourable influences either potential orexisting. Scoring: 1=ecosystem with little capacity to recover; 2=ecosystem capable of resisting minor impacts or rapid recovery; 3=highlyresistant or resilient ecosystem.

RARbio: Rarity (biological acceptation). Habitat encountered more or less frequently. Scoring: 1=habitat common through a wide region; 2=habitatendemic to a restricted zone or very scattered through the region; 3=habitat known in only one or few sites.

ECON: Economic importance. Evaluation of the economic importance of a given habitat, being it either direct, due to its richness in species exploitedby fishery, or indirect, due to its significance in the trophic web or of its possible tourist exploitation. Scoring: 1=no economic importance;2=moderate importance to local fisheries or diving tourism; 3=high importance for the occurrence of valuable biological resources (e.g., preciousred coral, appreciate fish or seafood) and/or because intense visitation by divers.

AESTbio: Aesthetic value (biological acceptation). Evaluation of the aesthetic value of a given habitat. Scoring: 1=monotonous and flat biotic cover;2=heterogeneous living cover, with some canopy development; 3=diverse and colourful habitats, with significant vertical structure and rich associated biota.

Criteria for Accessibility evaluation

Accessibility =DIV+MORPH+TURB

DIV: Diving certification. Diving certification required to access the site in terms of depth. Scoring: 3=1st level (18m max); 2=2nd level (30m max);1=deep or technical level (more than 30m).

MORPH:Morphology. Difficulty linked to the morphology of the seascape. Scoring: 3=easy orienting; 2=orienting in some part difficult, necessity ofcompass diving; 1=orienting difficult, risk related to morphological or human elements (e.g. caves, fishnets, wrecks) or seascape not allowing to setreference points.

TURB: Turbidity. Difficulty linked to reduced visibility underwater. Scoring: 3=clear water, with slightly reduced visibility only in case of incoming orrecently occurred swells; 2= likely occurrence of reduced visibility conditions (3 to 6m); 1= frequent occurrence of low visibility conditions (< 3m).

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evaluation unit, and then averaged at the site level. For eachsite, the two synthetic indices GeoH and BioH werecalculated through formulas inspired by the one used byBianchi (2007) to compute environmental quality:

Xi ¼ Ai � Bi � Ci �Di � Eið Þ � k 1�nð Þ

where Xi is the relevant synthetic index (GeoH or BioH) for thesite i; Ai to Ei are the scores assigned for the individualsubcategories to the site i; k is the maximum value assumedby such scores (3 in this case) and n is the number ofsubcategories considered (5 in this case). In theory, bothGeoH and BioH vary on a scale from 1 to 3. However, theformulation adopted is severe, so that high values of thesynthetic index require high scores for all subcategories: if, forexample, just one out of the five subcategories scores 1 (all theremaining four scoring 3), the synthetic index will be 1. Inpractice, this implies that values of these synthetic indiceshigher than 1 will rarely be met. Accessibility was also scored1 to 3, taking into account the following three criteria(Table 1): (i) level of diving certification required to visit thesite (DIV); (ii) the morphology of the seascape (MORPH); and

(iii) water turbidity (TURB). While the first two were obtainedmostly from the depth of the site and direct scuba surveys,respectively, the latter was derived from water transparencydata found in the literature (Della Croce, 1980; Della Croceet al., 1994; Morri and Bianchi, 2001). The total accessibilityof a site is the sum of the values for the three criteria.

In order to compare the sites, GeoH and BioH values for eachsite have been plotted in a bubble diagram, a scatter plot wherethe dimension of the bubble is proportional to the accessibilityof the site. Such a diagram gives a synoptic view of the wholeMNH value (along the diagonal of the graph) and of the needfor management measures (the size of the bubble).

RESULTS

In total, 14 landforms (including deposits), 16 habitats and threetypes of human impact were identified (Table 2 and Figures 3and 4). At each site, landforms and habitats were given a scorefor each subcategory (Figure 5). GeoH subcategories with thehighest score (mean> 2) were Representativeness and Aestheticin Punta Manara, and Paleogeographic and Integrity in Finale –

Table 2. Table2Geomorphologic and ecological elements assessed in the six surveyed sites, and main human impacts recorded. Habitat codesaccording to EUNIS classification URL: http://eunis.eea.europa.eu

Site ! A B C D E F G H I J K L

LandformsPlunging cliff + + +Plunging cliff with structural landforms +Rocky outcrop + + +Rocky outcrop with structural landforms + + + +Bioconstruction + + + + + + +Tidal notch + +Abrasion notch or pothole + + +Faulting of the bedrock (certain or inferred) + + + + +Rockfall + + + +Isolated blocks + + + +Rounded pebbles below closure depth + +Biodetritic sediment + + + + + +Loose sediment + + + + + + + + +Beachrock +HabitatsMediterranean communities of fine sands in veryshallow waters (A5.235)

+ +

Mediterranean communities of wellsorted fine sands (A5.236)

+ +

Mediterranean communities of infralittoralalgae moderately exposed to wave action (A3.23)

+ +

Infralittoral mixed sediments (A5.43) + +Overgrazing facies with incrusting algae and sea urchins (A3.131) + + +Mediterranean association with Corallina elongata (A3.136) + +Facies with large Hydrozoa (A3.335) +Association with Flabellia petiolata andPeyssonnelia squamaria (A3.23 J)

+ + + +

Mediterranean communities of muddy detritic bottoms (A5.38) + + + +Mediterranean animal communities ofcoastal detritic bottoms (A5.46)

+ + + + + + +

Facies with large Bryozoa (A5.463) +Mediterranean coralligenous communitiessheltered from hydrodynamic action (A4.32)

+ + +

Facies with Lophogorgia sarmentosa (A4.322) +Facies with Paramuricea clavata (A4.26B) + + + +Features of circalittoral rock. Semi-dark caves (A4.7) + + +Caves and overhangs with Parazoanthus axinellae (A4.712) +Human impactsLost fishnets +Date mussel harvesting +Wastes +



Vado Ligure (Figure 5(a)). The BioH subcategories, Naturalnessand Vulnerability scored most highly in both areas (Figure 5(b)).

Accessibility of some coastal sites in both areas was high (i.e.A, B and G, H, respectively) (Figure 6): the shallow depth,

together with simple coastal morphology (i.e. possibility to setreference points in underwater routes), allow easy access forfirst-level divers. In contrast, accessibility of deep sites (C to Fand I to L, respectively) was low, mainly because of the

Figure 3. Block diagrams of the geomorphologic and biological SCUBA surveys at sites in the Punta Manara area. Habitat codes refer to thosedescribed by EUNIS (European Union Nature Information System, European Environment Agency, http://eunis.eea.europa.eu).

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higher-level of dive certification needed to access them. Here,the difficulties linked to the morphology of the underwaterseascape are high because of the presence of lost fishing netsand the necessity, at some points, of advanced diving skills(e.g. compass diving for navigation between outcrops in sitesD, I and J). In respect of water turbidity, Della Croce (1980)and Della Croce et al. (1994) showed that water transparency(Secchi disk) was higher in the Finale – Vado Ligure area(16.8m) than in Punta Manara (11.4m).

Four sites at Punta Manara (C, D, E, F) exhibited values ofBioH higher than those of GeoH (Figure 7). Two sites at Finale– Vado Ligure (J, L) exhibited values of BioH higher than any ofthose at Punta Manara. The coastal sites in both areas (A, B, G,H), together with site I, had values of GeoH higher than those ofBioH (Figure 6), suggesting that expert judgement (on which isbased the UNEP-MAP scoring system) is apparently inclined togive shallow water habitats a lower value than deep water ones.Such depth-related bias is not to be expected for submerged

Figure 4. Block diagrams of the geomorphologic and biological SCUBA surveys at the sites in the Finale – Vado Ligure area. Habitat codes refer tothose described by EUNIS (European Union Nature Information System, European Environment Agency, http://eunis.eea.europa.eu).



landforms, so that the shallow-water sites B andG had highGeoHvalues, comparable with those of the deeper sites J and L.

Considering MNH as a whole, the highest value was shown bytwo sites J andL (Figure 7) from the non-SCIFinale –VadoLigurearea. Five out of the six sites from the SCI area of Punta Manara(B, C, D, E and F) exhibited medium MNH values, as did thenon-SCI site K. MNH values were low at the remaining sites(A, G, H and I), mostly due to the geomorphological component.

DISCUSSION

Selection of marine SCI sites

As previously emphasised, the criteria used in the selection ofmarine SCIs are at present dominated by biological values

and are affected by the difficulties of implementing the EUHabitats Directive in the marine environment (Hiscock et al.,2003; Derous et al., 2007). In Liguria, the marine SCIs wereoriginally proposed (and accepted by EU) because of theoccurrence of P. oceanica meadows (Relini et al., 2000),leaving other habitats, such as rocky reefs, largelyunmanaged. To fill this gap, at least partially, the boundaries ofsome of the already established SCIs, including Punta Manarahave been expanded.

Results showed that the sites included in the SCI of PuntaManara (C, D, E and F) had higher BioH scores than theothers in the same area (A and B). In this case, the evaluationscheme was in full agreement with the SCI boundaries. In thenon-SCI area of Finale – Vado Ligure area, the sites J, K andL had high BioH values, comparable with those of PuntaManara, suggesting therefore that this could be a suitablecandidate for the establishment of a new SCI. However, noSCI is envisaged here, and the unanswered question iswhether this is based on a reasoned decision (e.g. these sitesare too sparse to allow for adequate management measures)or simply because of the administrative difficulty inestablishing new SCIs after the formal approval by the EU ofthe initial proposals.

Figure 5. Mean values (+SD) of the GeoH (a) and BioH (b) subcategories in Punta Manara and Finale – Vado Ligure areas.

Figure 6. Accessibility scores of each site in Punta Manara (a) andFinale - Vado Ligure (b) areas, with the contribution of three criteria

(diving certification, morphology, turbidity) to the total value.

Figure 7. Total GeoH and BioH scores of the sites in Punta Manaraand Finale – Vado Ligure areas. Diameter of the bubbles isproportional to the accessibility of the site. See text for explanation.

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Geoheritage: an added value

As a consequence of the marine SCIs of Liguria being selectedexclusively on the basis of biological values (Relini et al., 2000),most of the sites inserted in the SCI of Punta Manara scoredlow in terms of GeoH, while high GeoH scores characterizedfour non-SCI sites (G, J, K and L). In two of these non-SCIsites (J and L), GeoH made an important addition to BioH,so that their MNH value as a whole was at the top of bothSCI and non-SCI areas (Figure 7). In site K, GeoH and BioHvalues were similar to each other: here biotic heritage values,which are more widely perceived at a social level, can act as‘flags’ to promote public appreciation of the abiotic heritage.Should the latter alone be considered in future managementplans, sites like G, which had high GeoH values but lowBioH values, might become worthy of conservation.

Accessibility: a stairway to perception

According to the European Landscape Convention (Council ofEurope, Florence, 20 October 2000), a landscape is part of aterritory as perceived by people. Consequently, accessibility ofmarine sites is fundamental for the perception, and thereforethe consideration, of the marine territory and its values.

In this study, accessibility was evaluated solely in relation toscuba diving, here considered as being both the main ‘use of’and ‘threat to’ the MNH: on one hand, underwater tourismmay represent a significant source of income for the activeconservation of marine areas, and might therefore beencouraged (Depondt and Green, 2006); on the other hand, itmay impact submarine ecosystems and thus need to bemanaged (Davis and Tisdell, 1995; Lloret et al., 2006). Thebasic principles of the methodology suggested, however,might be applied, with opportune translations, to otherhuman activities on the MNH (Milazzo et al., 2002).

The increased popularity of diving tourism in the lastdecades has stimulated the need for greater accessibility tounderwater environments. In some regions, scuba diving isshifting from a niche business to an ecotourism industry forwhich the knowledge of MNH is important in terms of bothpromotion and management (Van Treeck and Schuhmacher,1998; Shafer and Inglis, 2000; Dinsdale and Harriott, 2004;Roman et al., 2007). Liguria is an important destinationfor dive tourists from Italy and central Europe, with up to50 000 dives per year occurring at the most popular locations(Cattaneo Vietti and Tunesi, 2007). The two areas addressedin this study are also much visited by scuba divers, especiallyduring the summer months. The high accessibility of shallowcoastal sites allows their use as ‘diving gyms’ for first-level divers,enriching their necessary training with some fundamentalenvironmental education. Accessibility is intertwined directly alsowith some of the subcategories of GeoH and BioH. As an

example, the low vulnerability of the habitats at many of thesesites (Figure 5(b)) makes them suitable for novices to gainexperience, since the most delicate and fragile organisms, whichcan easily be damaged by inexperienced divers (Di Franco et al.,2009), are absent. On the other hand, the low accessibility ofdeep sites can assure a level of self-protection, as they willpresumably be visited by a restricted number of experienceddivers only.

Open issues

One of the main issues related to the evaluation scheme is the waythe shift from landform and habitat (fundamental evaluation units)to site-level scores is realized. Three main criteria have beenidentified (Table 3): each has advantages and disadvantages butnone can be considered as the best in absolute terms (Bianchi,2007). In this study, scores at site level have been calculated byaveraging the scores of the landforms or habitats contained ineach site (third criterion in Table 3). In other cases, depending onthe specific finalities, other criteria might be preferred. As anexample, studies aiming at highlighting geodiversity orecodiversity values will sum the scores of all landforms orhabitats at the site (first criterion in Table 3). The comparison ofthe scores obtained with different criteria could be a guide to thechoice of the best approach.

A methodology for MNH evaluation that involves themeasurement of both biological and geomorphological values,has rarely been developed but is nevertheless necessary forMNH management. While it is clear that geomorphology andecology are intimately linked (Rovere et al., 2007, 2009 andreferences therein), only ecological components are typicallytaken into account in the identification of vulnerable marineareas (Zacharias and Gregr, 2005), even though humanimpacts may be modulated by geomorphology (Rouphael andInglis, 1997).

The approach here, for the first time, attempted to evaluateindependently, but on the same numerical scale and adoptingsimilar criteria, both GeoH and BioH. Putting the two valuesorthogonally enabled the importance of a site to be visualizedaccording to either one value or both, which is important formanagers. In addition, estimating accessibility clearlyprovides a first-hand, although rough, indication of theurgency of the need for protection. While the selection of sitesworthy of conservation has been rather subjective in the past,it is recommended that future marine planning actions adoptthe procedure we describe in order to guarantee a fullconsideration of MNH.

The study provides two examples on how to move fromsimply mapping and describing the marine environment todefining values that have management significance. Theapplication of the procedure to a SCI and a non-SCI area ofLiguria, produced some significant results.

Table 3. Three main criteria for shifting from scores at landform and habitat level to scores at site level, with their respective advantages anddisadvantages

Criterion Advantage Disadvantage

Site score is the sum of all the scores of landformsor habitats contained in the site

The value of geodiversity and ecodiversity isincluded in the resulting score

Do many low-value landforms orhabitats equate a high-value one?

Site score is the maximum score of any singlelandform or habitat contained in it

The occurrence of high-value landforms orhabitats is shown out

Geodiversity and biodiversityvalues are ignored

Site score is the mean of the scores of landformsor habitats contained in it

Site score is not inflated by the co-occurrence ofmany low-value landforms or habitats

Excellence flanked by mediocrity willproduce moderate goodness



1. Most sites in the SCI area had high BioH values, whichsupports the subjective choice made in the past.However, there are sites in the non-SCI area thatexhibit even higher BioH value (according to EUNISscores), but were not even taken into consideration.

2. Values of geological heritage (UNESCO, 1972) hadnever been considered in past plans for the marineterritory and this has led to the paradox that there maybe a non-SCI area containing higher GeoH value thana SCI area. Adopting the methodology here presentedwill help avoid such bias in the future.

3. The highest MNH, considered as a whole, was found attwo non-SCI sites. To the best of our knowledge, noprevious attempts to estimate MNH exist, in Liguria orelsewhere in the Mediterranean Sea. We recommendMNH to be considered in future plans using a graphicalrepresentation to visualize immediately those sites withthe highest combination of both GeoH and BioH, andhence MHN as a whole.

4. Assessing accessibility provides managers with an indicationof the likely intensity of visitors, which is important whendeciding how to zone activities in the future.

ACKNOWLEDGEMENTS

Aerial photographs, sidescan sonar and multibeam data werekindly provided by Regione Liguria (Genoa, IT): we especiallywish to thank G.Diviacco and S.Coppo for their collaboration.We also thank S.Kershaw (London, UK), M.Vacchi andF.Ferraris (Genoa, IT), N. Polunin (Newcastle-upon-Tyne,UK), and T. J.Willis (Nelson, NZ) for their useful commentson earlier versions of the manuscript. Criticism by J.Baxter(Edinburgh, UK), K.Hiscock (Plymouth, UK), and ananonymous referee helped to improve the paper.

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