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1 Examining the Impacts of Recreational SCUBA Divers on 1 Subtropical Rocky Reef Systems in Mozambique 2 3 Amy O’Brien a* , Yara Tibiriçá b , Claire Eatock a . 4 5 a Falmouth Marine School, Killigrew Street, Falmouth, Cornwall, TR11 3QS, UK 6 [email protected] 7 [email protected] 8 b Lemanja – Zavora Marine Lab., Inharrime, Prov. Inhambane, Mozambique 9 [email protected] 10 11 Abstract 12 Reef systems are under threat worldwide from a variety of anthropogenic 13 activities. With an increase in the number of recreational SCUBA divers worldwide 14 more divers seek the warm, clear waters and high biodiversity associated with 15 tropical and subtropical reefs. As a result concerns have been raised regarding the 16 impact this increase in visitors may be having on the health status of reefs globally. 17 We examined the diving behaviour of 85 divers in Zavora, Mozambique to assess 18 correlations between diver characteristics and observed behaviour underwater. 19 Several diver impact studies have been conducted on tropical reefs worldwide, this 20 is the first study to be conducted on subtropical rocky reef systems. The results 21 show that while 87.1% of divers made contact with the reef benthos at least once 22 * Corresponding author. Present address: 1 Burley Court, New Street, Falmouth, Cornwall, TR11 3HJ, UK. Tel.: +441326-317751.

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Examining the Impacts of Recreational SCUBA Divers on 1

Subtropical Rocky Reef Systems in Mozambique 2

3

Amy O’Briena*, Yara Tibiriçá b, Claire Eatocka. 4

5

a Falmouth Marine School, Killigrew Street, Falmouth, Cornwall, TR11 3QS, UK 6

[email protected] 7

[email protected] 8

bLemanja – Zavora Marine Lab., Inharrime, Prov. Inhambane, Mozambique 9

[email protected] 10

11

Abstract 12

Reef systems are under threat worldwide from a variety of anthropogenic 13

activities. With an increase in the number of recreational SCUBA divers worldwide 14

more divers seek the warm, clear waters and high biodiversity associated with 15

tropical and subtropical reefs. As a result concerns have been raised regarding the 16

impact this increase in visitors may be having on the health status of reefs globally. 17

We examined the diving behaviour of 85 divers in Zavora, Mozambique to assess 18

correlations between diver characteristics and observed behaviour underwater. 19

Several diver impact studies have been conducted on tropical reefs worldwide, this 20

is the first study to be conducted on subtropical rocky reef systems. The results 21

show that while 87.1% of divers made contact with the reef benthos at least once 22

* Corresponding author. Present address: 1 Burley Court, New Street, Falmouth, Cornwall, TR11 3HJ, UK. Tel.: +441326-317751.

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during the observation period there were no significant correlations between any 23

of the variables analysed. We suggest that a combination of briefings, focused on 24

environmental awareness, and dive staff intervention during dives is required to 25

ensure the sustainability of Zavora’s diverse reef systems. 26

27

Keywords: Environmental impact; Marine tourism; Mozambique; Rocky reef; 28

SCUBA diving; Subtropical. 29

30

1. Introduction 31

SCUBA diving has been used recreationally since the 1940s (Garrod and Gossling, 32

2008). Recent figures from PADI show that they have certified 18 459 295 divers 33

worldwide since they began operation in 1967 (PADI, 2010). As diving tourism 34

increases so does the potentially damaging impact of inexperienced or careless 35

divers on fragile ecosystems. 36

37

This rise in diver certifications coincides with a significant increase in 38

international tourism which doubled from 1990 to 2009 (UNWTO, 2010). In 2009 39

alone 440 000 000 international tourists were travelling purely for leisure, 40

recreation and holidays (UNWTO, 2010). The development of global travel has 41

exposed previously isolated locations to mass tourism. Provisional figures from 42

the World Tourism Organization suggest that between 2007 and 2009 tourists 43

visiting Mozambique increased by 32% from 771 000 to 2 386 000 (UNWTO, 44

2010). 45

46

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Mozambique was in a state of civil war from 1977-1992 and consequently has 47

been relatively untouched by the tourism sector until more recent years (Ministério 48

Do Turismo, 2004). As a result the Mozambican coastline, which stretches 49

approximately 2700km along the Indian Ocean, remains relatively undeveloped 50

with areas of comparatively pristine marine life (Tibiriçá et al., In press). Praia de 51

Zavora is located in southern Mozambique and since the opening of the first dive 52

centre in 2008 has developed a reputation as an excellent dive spot with beautiful 53

reefs. These reefs support an abundance of marine life including one of the main 54

attractions, manta rays (Manta birostris and Manta alfredi). Other charismatic 55

species frequenting the productive local waters include whale sharks (Rhincodon 56

typus) and humpback whales (Megaptera novaeangliae), which are a major 57

attraction for tourists and recreational divers (Tibiriçá et al., In press). 58

59

Coral reefs are a habitat of global importance. Despite covering as little as 0.2% of 60

the ocean floor coral reefs have been estimated to support 25% of all marine life 61

(Cesar et al., 2003). Reef systems protect the coastline by acting as a natural 62

barrier against strong wave action, yield a high biodiversity of fish species which in 63

turn support local fishing communities and provide the opportunity for 64

communities to capitalise on the growing international tourism industry 65

(Conservation International, 2008; Spalding et al., 2001). Globally, coral reefs are 66

under threat from various impacts including: pollution; sedimentation; 67

unsustainable and damaging fishing methods; climate change; direct physical 68

impacts from activities such as mooring boats and recreational diving. It has been 69

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reported that 60% of the world’s coral reefs are ‘seriously at risk’ from the 70

cumulative impact of anthropogenic stresses (Cesar et al., 2003). 71

72

The warm, clear waters supporting coral reef systems make for ideal diving 73

conditions and are a major attraction for divers of all levels of experience (White & 74

Rosales, 2004; Cesar et al., 2004). Various studies have been conducted to assess 75

the impact that recreational divers may be having on coral reefs and also to 76

ascertain which diver characteristics may have a significant impact on the damage 77

caused to the reef. Evidence suggests that certain diver characteristics may have 78

an impact on the number of contacts made with coral and the damage caused. Key 79

characteristics include: diver qualification and experience; gender; attending a 80

dive briefing and the use of underwater photography (Barker and Roberts, 2004; 81

Davis and Tisdell, 1995; Luna et al., 2009; Medio et al., 1997; Rouphael and Inglis, 82

1997, 2001; Uyarra and Cote, 2007; Worachananant et al., 2008). 83

84

Roberts and Harriott (1994) found that damage to the reefs was more likely to be 85

caused by inexperienced divers (divers who had logged <100 dives) than more 86

experienced divers. This work has subsequently been supported by the findings of 87

Zakai and Chadwick-Furman (2002) and Barker and Roberts (2004). Male divers 88

have been recorded to cause significantly more damage to coral than female divers 89

(Rouphael and Inglis, 1997, 2001) however the later of the studies demonstrated 90

that females were more likely to contact the substrate with their hands. 91

Conversely, findings by Worachananant et al. (2008) show that females cause 92

significantly more damage to coral. Studies by Davis and Tisdell (1995), Medio et 93

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al. (1997) and Worachananant et al. (2008) conclude that attendance at a pre-dive 94

briefing reduced diver contacts. Barker and Roberts (2004) observed divers after 95

receiving a “one sentence environmental briefing” and found that it had no impact 96

on the contact rate but found dive leader intervention to have a significant impact. 97

The length and content of the briefing is likely to have influenced the results of 98

these studies. Barker and Roberts (2004) found that underwater photographers 99

caused significantly more damage to the reef than non-photographers however 100

photographer experience (non-specialist or specialist) had no significant effect. 101

Medio et al. (1997), Worachananant et al. (2008) and Luna et al. (2009) also found 102

photographers made significantly more contacts with the reef than non-103

photographers. 104

105

Several studies have found fin kicks to be the most common cause of unintentional 106

contact with the reef whilst the divers’ hands were used most frequently to 107

intentionally touch the substrate (Barker and Roberts, 2004; Luna et al., 2009; 108

Medio et al., 1997; Worachanant et al., 2008). 109

110

The aim of this study was to assess the direct impact of recreational SCUBA divers 111

on the reef systems of Praia de Zavora, Mozambique. The study used trained 112

interns to observe the behaviour of divers in order to examine the effect of certain 113

diver characteristics on the rate of contact and any subsequent damage caused to 114

the reef benthos. 115

116

2. Methodology 117

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2.1 Study site and diver samples 118

SCUBA divers were observed from March 2010 to January 2011 at Praia de Zavora, 119

Inhambane, Mozambique. Divers were accompanied on their dives by Y. Tibiriçá 120

and one or two trained interns. Tibiriçá lives at the location and heads a scientific 121

internship program whilst conducting environmental talks for guests at the local 122

resort and for children at a nearby school. Many of the divers were aware that 123

Tibiriçá was sampling the area for biodiversity and of the involvement of interns 124

however, all of the observed divers remained unaware of the specific nature of the 125

research. When asked about the research interns only discussed manta ray 126

identification or the health status of the reefs. During the dive the observers 127

buddied up and became a natural part of the dive groups. These measures were 128

taken to prevent any changes in the behaviour of the divers due to the presence of 129

the observers. To reduce bias in data collection Tibiriçá trains all of the interns on 130

site and monitors their work. 131

132

Divers were chosen using stratified random sampling. On each dive one diver was 133

observed from their entry into the water for 30 consecutive minutes, or until they 134

began their ascent (whichever came first). Towards the end of their stay in Zavora 135

all divers were also asked to complete a questionnaire to determine many factors 136

including; dive history, dive experience in Zavora, purpose of the visit to 137

Mozambique and Zavora. 138

139

2.2 Dive sites 140

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All of the divers were diving with MozDivers who took guests to a variety of 141

inshore and offshore dive sites all of which were accessed by boat. The depths at 142

the dive sites varied from 7 to 33 metres. The dive sites were usually determined 143

prior to launching the boat based on the weather and sea conditions and guest 144

specifications and experience. The appropriate briefing was given by the 145

divemaster to all divers prior to leaving the dive centre. This included a mention 146

of the dive company’s no-glove policy aimed at deterring divers from touching the 147

reef. 148

149

2.3 Factors Recorded 150

At each dive site observations were made about the physical conditions and 151

nearby activity including: time, location, weather, wind, air temperature, surface 152

and bottom water temperature, boat activity within 1km of the site, current and 153

wave impact on a scale of 1-5, underwater visibility and key species observed 154

during the dive. 155

156

Some diver characteristics (gender, possession of a camera) were recorded prior 157

to the dive. Divers with photography equipment were classified as amateur if they 158

were using a basic point and shoot camera or professional if the equipment was 159

more advanced, videographers were also recorded. During the observation period 160

all contact made underwater by the diver was recorded as well as the time into the 161

dive, the depth at which the contact took place, the part of the diver’s body 162

involved in the contact, the type of substrate affected, whether it was intentional or 163

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unintentional and the result of the contact (no damage, abrasion, breakage or 164

sediment disturbance). 165

166

2.4 Statistical Analysis 167

SPSS was used to conduct Spearman’s rank correlation to explore the relationships 168

between the recorded diver characteristics (gender, number of dives logged, dive 169

qualification, camera possession) and each of the following sets of observed data: 170

number of contacts made with the substrate (contacts min-1); intentional contacts 171

(contacts min-1); intentional living contacts (contacts min-1); intentional not living 172

contacts (contacts min-1); unintentional contacts (contacts min-1); unintentional 173

living contacts (contacts min-1); unintentional not living contacts (contacts min-1). 174

Microsoft excel was used in conjunction with StatPlus to generate descriptive 175

statistics. 176

177

3. Results 178

3.1 Diver Characteristics 179

In total 85 divers were observed underwater for 30 minutes, or until ascent, 180

starting from their entry into the water. A majority (74.1%, n=63) of divers 181

observed were male. Table 1 shows the division of divers into four experience 182

groups based on the total number of dives they have logged (Worachanant et al., 183

2008). Under this classification the majority of the observation subjects (68.2%, 184

n=58) are considered expert divers having logged over 100 dives. Comparatively, 185

diver experience may also be determined using the individuals dive qualification 186

(Table 2). The observed divers were mainly qualified to ‘advanced’ level (49.4%) 187

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with far fewer divers at either end of the spectrum. However this classification 188

may not be a true representation of experience as any two divers with the same 189

qualification may have logged a different number of dives. 190

191

Of the 85 divers observed 51.8% (n=44) were photographers, of those: 61.4% 192

(n=27) amateur; 20.5% (n=9) professional; 18.2% (n=8) videographers. 86.4% of 193

divers in possession of underwater photography or filming equipment were male. 194

67.4% (n=58) of the observed divers also returned completed questionnaires at 195

the end of their stay in Zavora. 196

197

3.2 Observed Diver Behaviour 198

Overall, 87.1% (n=74) of the divers observed made contact with the substrate at 199

least once during the observation period, with a mean contact rate (contacts min-1) 200

of 0.18 ± 0.02 (mean ± S.E.) and a median of 0.11 contacts min-1. 201

202

Of the contact observed underwater 47.1% (n=208) were made by fins, closely 203

followed by 39.1% (n=173) of contacts being made by hand (Figure 1). 25% 204

(n=52) of fin contacts and 67.1% (n=116) of hand contacts were made to rock. 205

46.6% (n=97) of fin contacts compared to 14.5% (n=35) of hand contacts were 206

made to living organisms (Figure 2). 207

208

Of all the contacts made with the substrate 62.4% (n=252) resulted in no 209

noticeable damage. 28.7% of contacts with the substrate resulted in damage 210

(breakage or abrasion) and 8.9% of substrate contacts disturbed the sediment. 211

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212

3.3 The Impact of Diver Characteristics on Diver Behaviour 213

Analysis of the data, using Spearman’s Rank Correlation on SPSS, revealed that 214

there were no correlations between each of the observed diver characteristics 215

(gender, number of dives logged, dive qualification, camera possession) and each 216

of the observed data sets. 217

218

3.4 Diver profiles 219

Upon finding no correlations between the diver characteristics and the observed 220

data the profiles of the 10 divers with the highest contact rate (contacts min-1) 221

were isolated and examined (Table 3). This diver sample is 11.8% of the total 222

observation sample and accounts for 39.3% of contacts with the substrate 223

(contacts min-1). This sample set was compared with the profiles of the 10 most 224

damaging divers, those with the highest damage (combined breakage and 225

abrasion) rate (damages min-1) (Table 4). 90% of the divers ranked as the top 10 226

most frequent to contact the substrate were classified as ‘experts’ and were 227

responsible for almost half (44.4%) of the damage caused to the substrate. 228

Analysis of the top 10 profiles reveals that 91.2% of damages were caused by 229

11.8% of the observation sample. Further analysis of the whole data set shows 230

that 16.5% of the divers observed are responsible for 100% of the substrate 231

damages. 4 of the divers profiled appeared in both sample sets: 3 were ‘expert’ 232

divers and 1 was a ‘beginner’. 233

234

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4. Discussion 235

In this study diver contact with the substrate was common, occurring in 87.1% of 236

the diver surveys, but a majority of the contacts (62.4%) resulted in no damage. 237

Only 2.2% of contacts with the reef benthos resulted in coral breakage. A similar 238

result was also recorded by Talge (1991), who observed 90% of divers contacting 239

the reef with only 2% causing damage to corals, and Barker and Roberts (2004) 240

who recorded coral breakages in only 4.1% of substrate contacts. This study found 241

that 39.1% of all substrate contacts were made with rock. The reef systems at 242

Zavora are not true coral reefs. They are rocky reefs composed of limestone rock 243

which supports a range of flora and fauna including an array of coral species 244

(Tibiriçá, Personal communication). As a result parts of the reef may appear as 245

just rock but on closer inspection this rock may in fact support a vast range of 246

micro-organisms (Figure 3). Therefore further investigation is required to 247

establish whether diver contact with rock is actually having more of an impact on 248

the reef community than first meets the eye. 249

250

Concurring with previous studies (Barker and Roberts, 2004; Harriott et al., 1997; 251

Roberts and Harriott, 1994; Rouphael and Inglis, 2001; Worachanant et al., 2008; 252

Zakai and Chadwick-Furman, 2002) the largest single cause of contact with the 253

substrate was by fins (47.1%). 93.3% (n=194) of the fin contacts were 254

unintentional indicating a lack of diver control of buoyancy. However, the 255

proportion of fin contacts is substantially lower than the 81.4% recorded by 256

Barker and Roberts (2004). Their observation sample size was high in the Basic 257

category compared to Advanced, Leader and Instructor categories of divers and 258

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their data showed a significant positive correlation with number of dives logged 259

(dive experience) and contact rate (Barker and Roberts, 2004). If fin contacts with 260

the substrate are an indication of divers with poor technique (e.g. swimming and 261

buoyancy control) then the lower figure found in this study may be explained by 262

the high number of divers in the ‘expert’ category of this sample (Table 1). The 263

second most frequent contact made underwater in this study was by divers’ hands 264

(39.1%). The vast majority (97.1%) of these contacts were intentional of which 265

83.9% resulted in no damage. Again this may be an indication of more 266

experienced or environmentally conscious divers. Findings by Worachanant et al. 267

(2008) showed similar findings with 41.4% of contacts caused by fins and 31.1% 268

caused by hand. 269

270

Rouphael and Inglis (2001) hypothesised that divers using underwater cameras 271

would cause more damage to corals than those who did not due to a lack of proper 272

buoyancy control near to and an eagerness to get closer to the substrate. This 273

study found no such trend. 274

275

The disturbance and re-suspension of sediment occurred in 26.2% of contacts 276

observed during the surveys. Prior research suggests that long-term sediment 277

accumulation can have a negative impact on reef dwelling organisms (Rogers, 278

1990). Particularly susceptible to localised increases in turbidity are sessile 279

species such as corals and sponges. Sedimentation may also smother or abrade 280

organisms, reduce settlement opportunities or reduce the growth and 281

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reproduction rate of corals as a higher proportion of energy must be used to expel 282

the sediment (Luna-Perez et al. 2010; Rogers, 1990). 283

284

5. Conclusion 285

While other studies have identified links between diver behaviour and various 286

diver characteristics this study has found no such correlations. Of particular 287

interest in this study is the high number of ‘expert’ divers whose dive experience 288

would suggest a greater ability to control their movement underwater and 289

therefore exhibit a reduced rate of damaging contacts. Although only a minority of 290

individuals (12.9%) caused breakages 72.7% (n=8) of them were classified as 291

‘expert’ divers and none of them were considered ‘beginners’ (having completed 292

<25 dives). The lack of correlations combined with diver profile observations in 293

this study indicates that experienced divers are not necessarily practicing good 294

diving behaviour. This may be due to preconceptions they have regarding 295

appropriate diving behaviour being based on their own experience and 296

assumptions rather than being based on current knowledge. In this case a little 297

education could go a long way. 298

299

Regardless of dive experience, dive qualification, gender or camera possession 300

divers need to be educated thoroughly on the local environment and specific dive 301

sites prior to diving and monitored for the duration of their dive by local dive staff 302

who should be prepared to intervene when appropriate (shown to be effective by 303

Davis and Tisdell, 1995; Medio et al., 1997; Worachanant et al., 2008). Establishing 304

good management techniques and standard diver protocol is of particular 305

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importance with the prospect of two new dive centres to be opened in Zavora 306

within the next year (Tibiriçá, Personal communication). 307

308

6. Acknowledgements 309

We are grateful to the management and staff at MozDivers and Zavora Lodge for 310

allowing interns and Y.Tibirica to accompany guests on their dives to collect the 311

data. We also extend a sincere thank you to all of the interns for their help in the 312

field and all of the divers who gave their time to answer questionnaires. Thank 313

you to Edward O’Brien and Katie Sambrook for thoroughly proofreading and 314

critiquing this article. This research has been part-funded by Oceans Research, 315

South Africa. 316

317

7. References 318

Barker, N.H.L., Roberts, C.M., 2004. Scuba diver behaviour and the management of 319

diving impacts on coral reefs. Biological Conservation. 120, 481-489. 320

Cesar Environmental Economics Consulting, 2003. The economics of worldwide 321

coral reef degradation. Arnhem: CEEC. 322

Cesar, H.S.J., van Beukering, P., Pintz, S., Dierking, J., 2004. Economic valuation of 323

the coral reefs of Hawai'i. Pacific Science. 58, 231-242. 324

Conservation International, 2008. Economic Values of Coral Reefs, Mangroves, and 325

Seagrasses: A Global Compilation. Arlington: Conservation International. 326

Davis, D., Tisdell, C., 1995. Recreational scuba-diving and carrying capacity in 327

marine protected areas. Ocean and Coastal Management. 26, 19-40. 328

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Garrod, B., Gossling, S., 2008. New Fronteirs in Marine Tourism: Diving 329

experiences, Sustainability, Management. Amsterdam: Elsevier Ltd. 330

Harriott, V., Davis, D., Banks, S., 1997. Recreational diving and its impact in marine 331

protected areas in Eastern Australia. Ambio. 26, 173–179. 332

Luna-Pérez, B., Valle, C., Vega Fernández, T., Sánchez-Lizaso, J.L., Ramos-Esplá, A.A., 333

2010. Halocynthia papillosa (Linnaeus, 1767) as an indicator of SCUBA diving 334

impact. Ecological Indicators. 10, 1017-1024. 335

Luna, B., Pérez, C.V., Sánchez-Lizaso, J.L., 2009. Benthic impacts of recreational 336

divers in a Mediterranean Marine Protected Area. Journal of Marine Science. 66, 337

517-523. 338

Medio, D., Ormond, R.F.G., Pearson, M., 1997. Effect of briefings on rates of damage 339

to corals by scuba divers. Biological Conservation. 79, 91–95. 340

PADI, 2010. Worldwide Certification History - Graph [online]. Available at: 341

http://www.padi.com/padi/en/footerlinks/certhistorynum.aspx [03.12.10]. 342

República De Moçambique: Ministério Do Turismo, 2004. Strategic Plan for the 343

Development of Tourism in Mozambique (2004 – 2013) Volume I. Unknown: 344

República De Moçambique: Ministério Do Turismo. 345

Roberts, L., Harriott, V.J., 1994. Recreational scuba diving and its potential for 346

environmental impact in a marine reserve. In: Bellwood, O., Choat, H., Saxena, N. 347

(Eds), Recent Advances in Marine Science and Technology 1994. James Cook 348

University of North Queensland, Townsville, Australia, pp. 695-704. 349

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Rogers, C.S., 1990. Responses of coral reef organisms to sedimentation. Marine 350

Ecology Progress. 62, 185–202. 351

Rouphael, A.B., Inglis, G.J., 1997. Impacts of recreational SCUBA diving at sites with 352

different reef topographies. Biological Conservation. 82, 329-336. 353

Rouphael, A.B., Inglis, G.J., 2001. ‘‘Take only photographs and leave only 354

footprints’’?: an experimental study of the impacts of underwater photographers 355

on coral reef dive sites. Biological Conservation. 100, 281-287. 356

Spalding M.D., Ravilious C., Green E.P., 2001. World Atlas of Coral Reefs. Prepared 357

at the UNEP World Conservation Monitoring Centre. University of California Press, 358

Berkeley, USA. 359

Talge, H., 1992. Impact of Recreational Divers on Scleratinian Corals at Looe Key, 360

Florida. Proceedings of the Seventh International Coral Reef Symposium. 2, 1077–361

1082. 362

UN World Tourism Organization, 2010. UNWTO Tourism Highlights. Unknown: 363

UNWTO. 364

Uyarra, M.C., Côté, I.M., 2007. The quest for cryptic creatures: Impacts of species-365

focused recreational diving on corals. Biological Conservation. 136, 77-84. 366

White, A.T., Rosales, R., 2003. Community-oriented marine tourism in the 367

Philippines: Role in economic development and conservation. In: S. Gossling, ed. 368

Tourism and development in tropical islands: Political ecology perspectives. 369

Cheltenham: Edward Elgar Publishing, pp.237-262. 370

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Worachananant, S., Carter, R.W., Hockings, M., Reopanichkul., P., 2008. Managing 371

the impacts of SCUBA divers on Thailand's coral reefs. Journal of Sustainable 372

Tourism. 16, 645-663. 373

Zakai, D., Chadwick-Furman, N.E., 2002. Impacts of intensive recreational diving 374

on reef corals at Eilat, northern Red Sea. Biological Conservation. 105, 179-187. 375

376

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Table 1. Dive Experience of Observed Divers 377 Groups Frequency Percentage

Beginners (1-25) 12 14.1

Novices (26-50 dives) 7 8.2

Enthusiasts (51-100 dives) 8 9.4

Experts (more than 100 dives) 58 68.2

Total 85 100

378

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Table 2. Level of Diver Qualification 379 Qualification Level Frequency Percentage

Open Water 7 8.2

Advanced 42 49.4

Rescue 14 16.5

Divemaster 11 12.9

Instructor 7 8.2

Other (e.g. technical) 4 4.7

Total 85 100

380

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381 Figure 1. The Cause of Diver Contacts 382

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

50.0

Fin Hand Reg Cylinder Knee Other

Pe

rce

nta

ge

(%

)

Contact Cause

Fin

Hand

Reg

Cylinder

Knee

Other

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383 Figure 2. The Cause and Object of Diver Contact 384

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

Fin Hand Reg Cylinder Knee Other

Pe

rce

nta

ge

(%

)

Contact Cause

Hard Coral

Sponge

Soft Coral

Algae

Diver

Other

Silt

Sand

Rock

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Table 3. Profiles of the 10 divers with the highest contact rate 385

Rank Substrate contact rate

(min-1) Highest

Certification Total Logged

Dives Gender

Camera Possession

1 1.00 2 500 Male Amateur 2 0.89 5 970 Male Video 3 0.82 5 970 Male Video 4 0.67 2 25 Female No 5 0.57 3 245 Male Prof 6 0.40 2 150 Male No 6 0.40 3 200 Male Prof 6 0.40 3 200 Male Prof 6 0.40 6 495 Male Amateur

10 0.38 4 350 Male Amateur

386

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Table 4. Profiles of the 10 divers with the highest damage rate 387

Rank Damage Rate (min-1) Highest

Certification Total Logged

Dives Gender

Camera Possession

1 0.28 2 12 Male No 2 0.26 5 970 Male Video 3 0.23 2 25 Female No 4 0.21 2 340 Male Video 5 0.18 5 970 Male Video 6 0.13 2 150 Male No 7 0.10 4 110 Male No 8 0.07 2 36 Male Amateur 9 0.06 2 38 Male No

10 0.05 4 200 Male Amateur

388

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389 Figure 3. Photograph demonstrating the range of micro-organisms which can be found 390

upon closer inspection of the ‘rock’. 391