Recreational Divers Research Articles

A Short Report on Decompression Sickness Incidents in Andaman and Nicobar Islands

Objectives: Due to presence of extensively fascinating coral reef ecosystem in the continental shelf of Andaman and Nicobar Islands, people from all over the world visit these islands of India to indulge in recreational diving. An increased participation figure has also elevated the number of divers at risk for Decompression Sickness (DCS). Despite this, no scientific data are available on DCS incidents from India. Present study is aimed to evaluate the DCS incidents reported in these islands, treatment provided, and the outcome of the treatment. An attempt has also been made to calculate the approximate frequency of DCS in comparison to the participation figure. Methods: Study design is retrospective data analyses of a recompression chamber. Naval Diving Unit Port Blair has the only active decompression chamber available in the islands, and Govind Ballabh Pant Hospital Port Blair was used to collect information on DCS incidents that occurred during the mentioned period. Due to lack of authenticated generalized documents of divers’ health history and dive logs, the scanty information was gathered from the dive centres on the basis of personal interviews/communications among the SCUBA diving instructors. Results: A total of nine cases were reported during the span of last four and half years, and thus approximate frequency of DCS in Andamans was 0.2/10000 divers year. All of the patients recovered completely after receiving the Hyperbaric Oxygen Therapy (HBOT), with no residual symptoms. Conclusions: Incident rate of DCS in Andamans is lower than that in many other parts of the world; possible reason could be under-reporting of less severe DCS cases. During the study period, the number of DCS type II incidents presented for the treatment was higher than that of DCS type I incidents. HBOT proved a complete success in treating DCS cases in the island.

Analysis of the risk of diving accidents in military and recreational diving

Abstract The most common question that arose in the course of the analysis of the data concerned with the number of diving accidents in recreational diving as compared with the authors’ own experiences working with military divers was why the number of accidents in recreational diving is substantially higher than that obtained in military diving. The comparison of factors having a direct effect on diving safety, the scope of depths reached, the manner of conducting decompression and divers’ problems reported after diving completion allow to explain the reasons behind the common incidents occurring among recreational divers. The factors which had a very significant impact on safety level included diving frequency, adaptation to higher pressure conditions and overestimation of one’s skills in undertaking challenges.

Expectations of professional and recreational users of artificial reefs in the Gulf of Lion, France

Summary Artificial reefs (ARs) have been deployed in France primarily to sustain artisanal fishery; however, based on their perceptions of these coastal management tools they can also be frequented by other sea users. In this work, the perceptions of AR professional and recreational users (direct users only) were studied by focusing on three AR sites located along the Gulf of Lion coastline (northwestern Mediterranean Sea, France) to determine whether they were becoming multi-use sites or were negatively perceived. Between 2011 and 2012, semi-directed interviews with artisanal fishermen, recreational fishermen, recreational spear fishermen and SCUBA divers were conducted to characterize their profiles, levels of knowledge, and expectations regarding ARs and how well these expectations were satisfied. The results showed although ARs were designed for use by artisanal fishermen that they were also frequented by others, mainly the local populations. The enhancement of fish at AR locations to maintain target species (e.g. Sparus aurata, Mullus sp.) for fishing activities was a common expectation. There were also expectations specific to AR usage, which varied among the different sites and users. Several factors influenced user satisfaction, such as AR design and communications by local authorities regarding this coastal tool. The results of this study indicate that AR users have either neutral or positive perceptions regarding ARs. In addition to their ecological objectives, ARs have socio-economic potential; therefore effective strategies for their management should be explored.

Recreational Diver Behavior and Contacts with Benthic Organisms in the Abrolhos National Marine Park, Brazil.

In the last two decades, coral reefs have become popular among recreational divers, especially inside marine protected areas. However, the impact caused by divers on benthic organisms may be contributing to the degradation of coral reefs. We analyzed the behavior of 142 scuba divers in the Abrolhos National Marine Park, Brazil. We tested the effect of diver profile, reef type, use of additional equipment, timing, and group size on diver behavior and their contacts with benthic organisms. Eighty-eight percent of divers contacted benthic organism at least once, with an average of eight touches and one damage per dive. No significant differences in contacts were verified among gender, group size, or experience level. Artificial reef received a higher rate of contact than pinnacle and fringe reefs. Specialist photographers and sidemount users had the highest rates, while non-users of additional equipment and mini camera users had the lowest contact rates. The majority of contacts were incidental and the highest rates occurred in the beginning of a dive. Our findings highlight the need of management actions, such as the provision of pre-dive briefing including ecological aspects of corals and beginning dives over sand bottoms or places with low coral abundance. Gathering data on diver behavior provides managers with information that can be used for tourism management.

A red orange extract modulates the vascular response to a recreational dive: a pilot study on the effect of anthocyanins on the physiological consequences of scuba diving

Nutritional antioxidants have been proposed as an expedient strategy to counter the potentially deleterious effects of scuba diving on endothelial function, flow-mediated dilation (FMD) and heart function. Sixteen volunteers performing a single standard dive (20 min at 33 m) according to US Navy diving procedures were randomly assigned to two groups: one was administered with two doses of 200 mg of an anthocyanins (AC)-rich extract from red oranges, 12 and 4 h before diving. Anthocyanins supplementation significantly modulated the effects of diving on haematocrit, body water distribution and FMD. AC administration significantly reduces the potentially harmful endothelial effects of a recreational single dive. The lack of any significant effect on the most common markers of plasma antioxidant capacity suggests that the mechanism underlying this protective activity is independent of the putative antioxidant effect of AC and possibly involves cellular signalling modulation of the response to high oxygen.

The effect of using a pre-dive checklist on the incidence of diving mishaps in recreational scuba diving: a cluster-randomized trial.

Scuba diving mishaps, caused by equipment problems or human errors, increase the occurrence of injuries and fatalities while diving. Pre-dive checklists may mitigate mishaps. This study evaluated the effect of using a pre-dive checklist on the incidence of diving mishaps in recreational divers. A multi-location cluster-randomized trial with parallel groups and allocation concealment was conducted between 1 June and 17 August 2012. The participants had to be at least 18 years of age, permitted to dive by the dive operator and planning to dive on the day of participation. They were recruited at the pier and dive boats at four locations. The intervention group received a pre-dive checklist and post-dive log. The control group received a post-dive log only. The outcomes, self-reported major and minor mishaps, were prompted by a post-dive questionnaire. Mishap rates per 100 dives were compared using Poisson regression with generalized estimating equations. Intent-to-treat, per-protocol and marginal structural model analyses were conducted. A total of 1043 divers (intervention = 617; control = 426) made 2041 dives, on 70 location-days (intervention = 40; control = 30) at four locations. Compared with the control group, the incidence of major mishaps decreased in the intervention group by 36%, minor mishaps by 26% and all mishaps by 32%. On average, there was one fewer mishap in every 25 intervention dives. In this trial, pre-dive checklist use prevented mishaps which could lead to injuries and fatalities. Pre-dive checklists can increase diving safety and their use should be promoted. Trial Registration: ClinicalTrials.gov ID NCT01960738.

The effect of recreational SCUBA divers on the structural complexity and benthic assemblage of a Caribbean coral reef

The effect of recreational SCUBA diving on coral reefs is likely secondary to many of the commonly cited stressors that threaten the long-term survival of coral reefs, such as rising temperatures. However, recreational SCUBA diving has had documented effects on various benthic organisms. Most research on the effect of SCUBA divers has focused on broken and abraded benthic organisms or the rate at which divers contact the benthos. We tested for differences in the structural complexity and benthic assemblage between pairs of heavily and lightly trafficked dive sites in Bonaire, a popular Carribbean diving destination. There was roughly 10 % less structural complexity in areas of heavy traffic. This is alarming given that the structural complexity of shallow reefs in Bonaire is substantially lower than in the 1970s. Different functional groups of benthic organisms were affected differentially by diving traffic. For instance, massive corals such as Orbicella annularis were 31 % less abundant at heavy than light diver traffic areas, while gorgonians and sponges had similar abundances at heavy and light diver traffic areas. Our results match those of previous studies on the resistance and resilience of tropical benthic reef organisms to physical disturbances that suggest that stony corals are more prone to physical damage than gorgonians and sponges. We provide a number of possible management strategies that could reduce the effects of recreational SCUBA divers on Bonaire and elsewhere, including education/intervention by dive guides and concentration of diving traffic away from areas of stony coral abundance.

Toward adaptive management of coastal MPAs: The influence of different conservation targets and costs on the design of no-take areas

There is still much discussion on the most appropriate location, size and shape of marine protected areas (MPAs). These three factors were analyzed for a small coastal MPA, the Luiz Saldanha Marine Park (LSMP), for which a very limited amount of local ecological information was available when implemented in 1998. Marxan was used to provide a number of near-optimal solutions considering different levels of protection for the various conservation features and different costs. These solutions were compared with the existing no-take area of the LSMP. Information on 11 habitat types and distribution models for 3 of the most important species for the local artisanal fisheries was considered. The human activities with the highest economic and ecological impact in the study area (commercial and recreational fishing and scuba diving) were used as costs. The results show that the existing no-take area is actually located in the best area. However, the no-take area offers limited protection to vagile fish and covers a very small proportion of some of the available habitats. An increase in the conservation targets led to an increase in the number of no-take areas. The comparative framework used in this study can be applied elsewhere, providing relevant information to local stakeholders and managers in order to proceed with adaptive management.

Protected Zones and Partnerships: Their Application and Importance to Underwater Cultural Heritage Management

The wreck of the Myola was discovered by recreational divers in July 1994. The site was protected as an historic shipwreck under the Australian Government’s Historic Shipwrecks Act 1976. However, a recommendation for the declaration of a Protected Zone around the site was not supported by the Minister responsible. Although the majority of divers strove to protect the site, significant damage was inflicted on the site. This has significantly reduced its archaeological potential as well as its visual appeal and subsequent recreational activity.

Can Artificial Reef Wrecks Reduce Diver Impacts on Shipwrecks? The Management Dimension

Managers have been advocating the use of artificial reef wrecks to diversify the experiences of recreational divers and thereby reduce the well-known impact on reefs. To examine whether artificial reef wrecks can serve as substitutes for historic shipwrecks this paper discusses the attitude of Australian divers to wreck diving in general and to artificial reef wrecks in particular. While the overwhelming majority of divers surveyed accepted the need for control, the experienced divers were less interested in artificial reef wrecks and less prepared to tolerate controls over their perceived freedom to dive wrecks. We present projections that show that this legacy issue will have largely resolved itself by 2025 due to attrition and natural ageing.

Evaluating PAI-1 as a biomarker for stress in diving: human serum total PAI-1 is unaltered after 2 h dry exposures to 280 kPa hyperbaric air

Plasminogen activator inhibitor (PAI-1) is induced in the vasculature and secreted into the vascular lumen in response to inflammation and oxidative stress. We have previously reported a fivefold increase in plasma PAI-1 from rats exposed to 708 kPa hyperbaric air. In the current study we assess the potential of human serum total PAI-1 as a biomarker for stress in compressed air diving. Eleven recreational divers, nine males and two females, completed four 2 h hyperbaric air exposures to 280 kPa in a pressure chamber over a period of 2 weeks. The air pressure corresponds to a diving depth of 18 m in water. Serum was collected before the study and again 3 h 30 min after completion of each hyperbaric exposure. All samples were taken in the afternoon to minimize the contribution of circadian variation. The analysis revealed no change in serum total PAI-1 after hyperbaric exposures within the group of divers (P = 0.064), but significant interindividual differences persisted throughout the study (P < 0.0005). A case of decompression sickness after the third round of hyperbaric exposure did not affect PAI-1. In conclusion, compressed air exposure to 280 kPa does not affect serum total PAI-1, and significant interindividual variation in PAI-1 levels may limit its usefulness as a biomarker. This does, however, not give a complete answer regarding PAI-1 in physiologically stressful dives. Further studies with different exposures and timing are needed for that.

Marine life preferences and perceptions among recreational divers in Brazilian coral reefs

Understanding diver preferences and perceptions of environmental attributes can help inform dive tourism management. We interviewed 190 recreational divers and examined their preferences for marine life in the Abrolhos National Marine Park, eastern Brazil. We also assessed divers' perceptions of changes in fish abundance when they revisit the dive site. Marine life preferences changed according with the divers' experience level. Novice divers preferred encounters with megafauna, whereas experienced divers preferred to see cryptic species. Individual perceptions of decline in fish abundance were influenced by longer time interval between visits. Visitors elicited the end of fish feeding, and illegal fishing, as the main causes of decline. Strategies to limit decline in the quality of marine life attributes, such as zoning and visitation limits based on carrying capacity estimates should be also based in divers' preferences and perceptions. Therefore, understanding divers' motivations and preferences will help maximize visitors' enjoyment and guide the dive industry into a more sustainable mode in the future.

Do reef fish habituate to diver presence? Evidence from two reef sites with contrasting historical levels of SCUBA intensity in the Bay Islands, Honduras.

Contact between humans and the marine environment is increasing, but the capacity of communities to adapt to human presence remains largely unknown. The popularization of SCUBA diving has added a new dimension to human impacts in aquatic systems and, although individual-level impacts have been identified, cumulative effects on ecosystem function and community-wide responses are unclear. In principle, habituation may mitigate the consequences of human presence on the biology of an individual and allow the quick resumption of its ecological roles, but this has not been documented in aquatic systems. Here, we investigate the short-term impact of human presence and the long-term habituation potential of reef-fish communities to recreational SCUBA divers by studying symbiotic cleaning interactions on coral reefs with differing levels of historical contact with divers. We show that incidences of human contact result in a smaller decline in ecosystem function and more rapid resumption of baseline services on a reef in Utila, Honduras that has heavy historical levels of SCUBA diver presence, compared to an un-dived reef site in the Cayos Cochinos Marine Protected Area (CCMPA). Nonetheless, despite the generally smaller change in ecosystem function and decades of regular contact with divers, cleaning behavior is suppressed by >50% at Utila when divers are present. We hypothesize that community-wide habituation of reef fish is not fully achievable and may be biologically restricted to only partial habituation. Differential responses to human presence impacts the interpretation and execution of behavioral research where SCUBA is the predominant means of data collection, and provides an important rationale for future research investigating the interplay between human presence, ecosystem function, and community structure on coral reefs.

An assessment of the effectiveness of in-situ signage in multiple-use marine protected areas in providing information to different recreational users

In-situ signage is a cost effective environmental education tool used in marine protected area (MPA) management, and the design and location of signage is crucial to attract the attention of targeted audiences. The implementation of multiple-use MPAs increases the challenges of communicating awareness of MPA boundaries and permitted activities. Currently, little is known about how effective signage in multiple-use MPAs is in communicating information to stakeholders that will promote supportive attitudes and behaviours towards MPAs. This study evaluated the usefulness of in-situ signage in an existing multiple-use MPA, to determine if signs pertaining to the MPA captured the attention of recreational users, and provided adequate information. Structured interviews with recreational fishers, divers, and other users, were used to determine users׳ awareness of being in an MPA, their awareness of management objectives and associated zoning scheme, together with levels of agreement or disagreement on whether or not current in-situ signage adequately communicates information about the MPA. It was evident that the types and accessibility of in-situ signs in the MPA may not be effective at capturing the attention of intended audiences and providing relevant information, with the exception of signs located at the dive site, due to their design, size, and placement. Awareness differed among the three user groups, together with their views on the effectiveness of signage. Many recreational fishers believed existing signage was inadequate and unclear, and expressed frustrations with the complexity of zoning rules and location of their boundaries. Based on this study, recommendations about the presentation, content, and placement of signage relative to access points, and information required by MPA users, is provided.

Theoretical tissue compartment inert gas pressures during a deep dive with and without deep decompression stops: a case analysis.

Deep decompression stops are increasingly common in recreational technical diving. Concerns exist that they shift decompression stress back into slower tissues. A diver recorded an exceptional exposure dive, with deeps stops, on a commercially available dive computer. Using the R package SCUBA tissue inert gas pressures in 17 Bühlmann (ZH-L16A) compartments were estimated from the dive computer recorded profile. The RGBM dive plan generated by the diver's software was similarly interrogated, as was a third profile with reduced deep stops generated using the VPM-B/E model. In this dive the combination of 5 gas switches appeared to ameliorate the effect of deep stops from 76 m depth. A higher-than-anticipated inert gas content in a decompression mixture, coupled with climbing 200 stairs post-decompression, appear possible risk factors for decompression sickness. Nonetheless, the physiological effect of deep decompression stops during exceptional exposure, even when diving with gas switches, remains urgently to be determined to improve safe decompression following exceptional exposures. Until algorithms utilising deep decompression stops are validated with human data, dive profiles incorporating deep decompression stops should be considered experimental.

Diving medicine in clinical practice.

Diving is a popular sport, and some recreational divers have medical risk factors. Their health can be endangered by high extracorporeal (ambient) pressure and its many systemic effects. We review relevant publications on free (breath-hold) diving, scuba diving, medical evaluation for diving, barotrauma, decompression sickness, and diving with medical risk factors, which were retrieved by a selective search of PubMed. Free diving or scuba diving, even at seemingly innocuous depths, puts considerable stress on the cardio - vascular system, ears, and lungs. Unexpected events while diving, diminished functional reserve, and pre-existing medical illnesses increase the risk of a diving accident. An international survey revealed that minor incidents occur in 1.3% of all dives, and decompression accidents in 2 of every 10 000 dives. A properly conducted medical examination to determine diving fitness, followed by appropriate counseling, can make a life-threatening diving accident less likely. To be able to certify diving fitness and give competent medical advice about diving, physicians must be well informed about the physical and physiological changes of diving and the associated risks to health, and they need to know how to perform a medical evaluation of prospective divers. In Germany, any licensed physician may judge a person fit to dive. It is recommended that this be done in adherence to the relevant evaluation standards and recommendations of the medical specialty associations. Randomized controlled trials on the effect of preventive behavior would be desirable, as would a central registry of diving accidents.

First record of Algarvia alba García-Gómez and Cervera, 1989 (Gastropoda: Heterobranchia) outside the type locality

The aeolid nudibranch species Algarvia alba Garcia-Gomez and Cervera 1989 was first described from two specimens collected in Sagres, Portugal (37°00’49^N, 008°55’31^W) in May 1988 (Garcia-Gomez and Cervera 1989). It has not been observed since and because the collected individuals were not photographed alive there was a particular interest on obtaining in situ images (Fig. 1). The increasing number of recreational divers sharing underwater photographs online and better communication and access to information has brought the casual observer closer to biologists with significant advantages for both. This change made possible the positive identification of an individual pictured in a photograph taken in the Cantabrian coast of Spain, thus providing the scientific community with an image of a live animal and also a better understanding of the possible distribution range. The picture was taken in Getaria (Gipuzkoa), Spain (43°18’34^N, 002°11’52^W), by Manex Cantalapiedra on July 20, 2013. The water temperature was approximately 15 ° C and there was a strong thermocline at 8 meters. The animal was seen at a depth of 14 meters, approximately, in a zone of sand and low stones. Although the animal was not collected, its key characteristics, namely the orange red color on a white background and particularly the very conspicuous enlargement on each side of the head, in front of the rhinophores, clearly match the original description. To the best of our knowledge, there is no other nudibranch species that can be confused with this one. Based on the lens used to take the picture, it is estimated that this specimen measured between 5 to 10 mm. Specimens used in the original description measured between 5 and 13 mm. The distance between the two sites at which the species was observed (Sagres and Getaria) exceeds, along the coastline, more than 1,200 km. In this case, a highly restricted endemism should be ruled out.

Intrapulmonary shunt and SCUBA diving: another risk factor?

Laboratory and field investigations have demonstrated that intrapulmonary arteriovenous anastomoses (IPAVA) may provide an additional means for venous gas emboli (VGE) to crossover to the arterial circulation due to their larger diameter compared to pulmonary microcirculation. Once thought to be the primary cause of decompression sickness (DCS), it has been demonstrated that, even in large quantities, their presence does not always result in injury. Normally, VGE are trapped in the site of gas exchange in the lungs and eliminated via diffusion. When VGE crossover takes place in arterial circulation, they have the potential to cause more harm as they are redistributed to the brain, spinal column, and other sensitive tissues. The patent foramen ovale (PFO) was once thought to be the only risk factor for an increase in arterialization; however, IPAVAs represent another pathway for this crossover to occur. The opening of IPAVAs is associated with exercise and hypoxic gas mixtures, both of which divers may encounter. The goal of this review is to describe how IPAVAs may impact diving physiology, specifically during decompression, and what this means for the individual diver as well as the future of commercial and recreational diving. Future research must continue on the relationship between IPAVAs and the environmental and physiological circumstances that lead to their opening and closing, as well as how they may contribute to diving injuries such as DCS.

Recreational diver preferences for reef fish attributes: Economic implications of future change

This study sought to quantify the potential effects of changes in Caribbean reef fish populations on recreational divers' consumer surplus. Over five hundred tourist SCUBA divers were interviewed at seven sites across three Caribbean countries representing a diversity of individuals within the Caribbean dive market. A choice experiment was used to assess willingness to pay as a function of the abundance and size of reef fishes, the presence of fishing activity/gear, and dive price. Despite some preference heterogeneity both between and within sites, the results indicate that future declines in the abundance of reef fishes, and particularly in the number of large fishes observed on recreational dives, will result in significant reductions in diver consumer surplus. On the other hand, improvements in fish populations and reduced fishing gear encounters are likely to result in significant economic gains. These results can be used to justify investment in pre-emptive management strategies targeted at improving reef fish stocks (namely reducing unsustainable fishing activities and land-based reef impacts), managing conflicting uses, as well as to indicate a possible source of financing for such conservation activities.

Effectiveness of recreational divers for monitoring sea turtle populations

Five sea turtle species, all globally threatened, are found in southern Mozambican waters. Illegal hunting of foraging turtles, nest raiding and modification of coastal habitat are assumed to affect local sea turtle populations, but a lack of capacity and resource constraints ham- per monitoring and compliance activities. Enlisting the recreational SCUBA diving community to report sea turtle sightings is a potential solution for population monitoring. The effectiveness of recreational divers as monitors was tested through the review of 2 approaches: the use of a routine dive logbook with sightings, and data from a dedicated survey. These approaches provided 37 consecutive months of data between 2008 and 2011 from dive sites in Inhambane Province, Mozambique. A total of 317 sightings of loggerhead Caretta caretta, green Chelonia mydas, hawksbill Eretmochelys imbricata and unidentified turtle species were reported from 918 dives. While the dedicated survey collected more detailed behavioural data (e.g. response to divers and feeding behaviour), independent logbook records provided a more robust data set for analysis of sighting trends. Useful data on sea turtle species composition, size and distribution were obtained from both approaches, although there were concerns with regard to species identification and size estimates. With refined methodology, particularly the incorporation of photographic verification of species identification, reports from divers can provide cost-effective and useful data for monitor- ing foraging turtle populations.