Recreational Divers Research Articles

A shallow-living benthic Rhodaliid siphonophore: citizen science discovery from Papua New Guinea

Benthic siphonophores of the family Rhodaliidae (Cnidaria, Hydrozoa) are extremely fragile, difficult to collect, and therefore little studied. Only a few records exist worldwide, so their ecology remains largely unknown. Rhodaliids have been found at most depth horizons, but until now were believed to mainly inhabit deeper water over continental shelves, with only a few records from ca. 100 m. In this paper, a new rhodaliid is described based on an underwater photograph provided by a recreational diver via Facebook. This observation was made in Milne Bay (Papua New Guinea) at a depth of 26–27 m, and constitutes the shallowest record so far for any rhodaliid. The specimen was tentatively identified as Archangelopsis typica based on observable morphological characters and an approximate estimate of connectivity between all rhodaliid species in the Indo-Pacific region. Additionally, we highlight the scientific potential of citizen science.

Efficacy of the U.S. Navy Treatment Tables in treating DCS in 103 recreational scuba divers

Despite the fact that current decompression schedules reduce the risk of decompression sickness (DCS), recreational scuba divers continue to experience DCS. Therapy outcomes in these divers are difficult to track. Our study aims to understand the efficacy of the United States Navy (USN) Treatment Tables (5, 6, 6A, 9) in providing symptomatic relief among recreational scuba divers. We conducted a single-center retrospective review of recreational divers treated from 2003 to 2013. A total of 187 divers were identified: 84 divers were excluded, and the charts of the remaining 103 divers were independently reviewed by three clinicians. For these 103 divers, the response variable, therapy outcome, was categorized as no relief, partial relief, or complete relief of symptoms. In a population of 76 males and 27 females with an average of three dives and three treatments, 53 patients achieved complete symptomatic relief, 45 patients had partial relief, and five patients reported no relief at the end of all recompression treatments. Among the patients who achieved complete symptomatic relief, 28 (53%) needed only one recompression treatment. The depth of the diver's first dive and the change in symptoms within the first 20 minutes of the first recompression treatment were found to be explanatory variables of the treatment outcome.

Evaluating the attractiveness and effectiveness of artificial coral reefs as a recreational ecosystem service

Artificial reefs are increasingly being used around the globe to attract recreational divers, for both environmental and commercial reasons. This paper examines artificial coral reefs as recreational ecosystem services (RES) by evaluating their attractiveness and effectiveness and by examining divers' attitudes toward them. An online survey targeted at divers in Israel (n = 263) indicated that 35% of the dives in Eilat (a resort city on the shore of the Red Sea) take place at artificial reefs. A second study monitored divers' behavior around the Tamar artificial reef, one of the most popular submerged artificial reefs in Eilat, and juxtaposed it with divers' activities around two adjacent natural reefs. Findings show that the average diver density at the artificial reef was higher than at the two nearby natural knolls and that the artificial reef effectively diverts divers from natural knolls. A third study that examined the attitudes towards natural vs. artificial reefs found that the artificial reefs are considered more appropriate for training, but that divers feel less relaxed around them. By utilizing the RES approach as a framework, the study offers a comprehensive methodology that brings together the aesthetic, behavioral, and attitudinal aspects in terms of which artificial reefs can be evaluated.

Underwater particle motion (acceleration, velocity and displacement) from recreational swimmers, divers, surfers and kayakers

When humans take to the water, they generate sound. This is helpful for the detection, classification, localisation and tracking of certain activities for purposes of border security, health and safety of offshore industrial development, environmental management, etc. The most commonly measured acoustic quantity is pressure. Vector quantities related to particle motion, such as particle velocity and acceleration, can equally identify the activity and they carry directional information. Acoustic pressure and particle motion were measured from 10 water sports activities within an Olympic-sized pool: swimming backstroke, breaststroke, butterfly and freestyle; snorkelling with fins; kicking a boogie board with fins; paddling with alternating or simultaneous arms while lying on a surfboard; scuba-diving; kayaking and jumping into the pool. Activities that occurred at the surface and that involved repeatedly piercing the surface were the strongest sound generators. Surface activities that produced fewer bubbles and scuba-diving at depth generated less broadband power. The vector fields around water sports activities can be expected somewhat different in the open ocean from within a pool, and more research is needed to understand how marine fauna might perceive these vector quantities.

Behaviour of recreational spearfishers and its impacts on corals

Abstract Recreational diving is a concern regarding its effects on benthic assemblages, especially on heavily dived coral reefs. However, spearfisher behaviour and the scale of damage they cause to corals remains unknown. The behaviour of recreational spearfishers was observed to determine their rate of physical contacts with corals. The experience level and fishes captured by spearfishers were assessed to establish their relationship with the number of contacts with corals. All spearfishers made contact with corals, at an average rate of 1.25 ± 0.1 SE touches per minute and caused physical damage at a rate 0.51 ± 0.04 per minute. Massive corals were most frequently touched and branching corals were most frequently damaged. Touches and damage occurred mainly through fin kicks, spearfisher bodies and spearguns. Contact rates varied according to spearfisher experience level and the fish they were targeting. Novice spearfishers showed no preference for specific targets while experienced spearfishers target mesopredator fishes. Spearfishing caused the highest known rates of touches and damage to corals among all the activities involving recreational diving. The activity may add to local stressors on corals, especially at sites with high visitation rates. Understanding how the factors that affect spearfisher behaviour and their effects on corals may help managers to develop strategies to mitigate the incidence of damaging behaviour.

Self-reported exercise behaviour and perception of its importance to recreational divers.

This study examined self-reported physical activity and perceptions of exercise importance among certified divers in two distinct age groups. Questionnaires were distributed by hand at dive sites in three states of the United States, half to students from an academic programme in scuba diving at a regional university. The survey included questions about health status, dive history, certification levels, structured exercise activity levels and perceived importance of regular exercise to their health, diving ability, and safety. Also included was the Godin-Shephard Leisure-Time Physical Activity Questionnaire, a validated physical activity classification instrument for use among adults. Non-students were older than the students and had greater diving experience. There was no detectable difference between groups in perceived exercise importance to health (p = 0.69), diving ability (p = 0.75), or diving safety (p = 0.25). Fitting age, sex, occupation and number of dives to a generalised linear model to predict Godin-Shephard scores, number of dives was removed first (p = 0.43), followed by student status (p = 0.33). Remaining predictors of Godin-Shephard exercise scores were age (-0.004 per year, p < 0.0001) and sex (males = + 0.11, 95% CI 0.04-0.17, p = 0.0012). Both groups reported similar structured exercise regularity, overall health and perceived importance of regular exercise for health, diving and safety. Despite acknowledging the importance of exercise, Godin-Shephard scores for physical activity decrease with age.

Executive Functions of Divers Are Selectively Impaired at 20-Meter Water Depth.

Moving and acting underwater within recreational or occupational activities require intact executive functions, since they subserve higher cognitive functions such as successful self-regulation, coping with novel situations, and decision making; all of which could be influenced by nitrogen narcosis due to elevated partial pressure under water. However, specific executive functions that could provide a differentiated view on humans’ cognitive performance ability have not yet been systematically analyzed in full-water immersion, which is a research gap addressed within this approach to contribute to a better understanding of nitrogen narcosis. In this study, 20 young, healthy, and certified recreational divers participated and performed three different executive-function tests: the Stroop test (Inhibition), the Number/Letter test (Task switching), the 2-back test (Updating/Working memory), and a simple reaction time test (Psychomotor performance). These tests were performed once on land, at 5-meter (m) water depth, and at 20-meter (m) water depth of an indoor diving facility in standardized test conditions (26°C in all water depths). A water-proofed and fully operational tablet computer was used to present visual stimuli and to register reaction times. Performance of the simple reaction time test was not different between underwater and land testing, suggesting that reaction times were not biased by the utilization of the tablet in water immersion. Executive functions were not affected by the shallow water immersion of 5-m water depth. However, performance scores in 20-m water depth revealed a decreased performance in the incongruent test condition (i.e., an index of inhibitory control ability) of the Stroop test, while all other tests were unaffected. Even though only one out of the three tested cognitive domains was affected, the impairment of inhibitory control ability even in relatively shallow water of 20-m is a critical component that should be considered for diver’s safety, since inhibition is required in self-control requiring situations where impulsive and automatic behavior must be inhibited. Our interpretation of these selective impairments is based on a discussion suggesting that different neural networks within the central nervous system, which process specific executive functions, are affected differently by nitrogen narcosis.

Does recreational scuba diving have clinically significant effect on routine haematological parameters?

IntroductionScuba diving represents a combination of exercise and changes in environmental conditions. This study aimed to evaluate changes in haematological parameters after recreational scuba diving in order to identify clinically significant changes.Materials and methodsThe study included males, 17 recreational divers, median age (range) 41 (30-52) years. Blood samples were taken before diving, immediately after diving to 30 meters for 30 minutes, 3 hours and 6 hours after diving. Complete blood counts were analyzed on the Cell Dyn Ruby haematology analyzer. Statistical significance between successive measurements was tested using Friedman test. The difference between the two measurements was judged against desirable bias (DSB) derived from biological variation and calculated reference change values (RCV). The difference higher than RCV was considered clinically significant.ResultsA statistically significant increase and difference judging against DSB was observed: for neutrophils immediately, 3 and 6 hours after diving (18%, 34% and 36%, respectively), for white blood cells (WBCs) 3 and 6 hours after diving (20% and 25%, respectively), for lymphocytes (20%) and monocytes (23%) 6 hours after diving. A statistically significant decrease and difference judging against DSB was found: immediately after diving for monocytes (- 15%), 3 and 6 hours after diving for red blood cells (RBCs) (- 2.6% and -2.9%, respectively), haemoglobin (- 2.1% and - 2.8%, respectively) and haematocrit (- 2.4% and - 3.2%, respectively). A clinically significant change was not found for any of the test parameters when compared to RCV.ConclusionsObserved statistically significant changes after recreational scuba diving; WBCs, neutrophils, lymphocytes, monocytes increase and RBCs, haemoglobin, haematocrit decrease, probably will not affect clinical decision.

Beneficial effect of enriched air nitrox on bubble formation during scuba diving. An open-water study

ABSTRACTBubble formation during scuba diving might induce decompression sickness.This prospective randomised and double-blind study included 108 advanced recreational divers (38 females). Fifty-four pairs of divers, 1 breathing air and the other breathing nitrox28 undertook a standardised dive (24 ± 1 msw; 62 ± 5min) in the Red Sea. Venous gas bubbles were counted (Doppler) 30–<45 min (early) and 45–60 min (late) post-dive at jugular, subclavian and femoral sites.Only 7% (air) vs. 11% (air28®) (n.s.) were bubble-free after a dive. Independent of sampling time and breathing gas, there were more bubbles in the jugular than in the femoral vein. More bubbles were counted in the air-group than in the air28-group (pooled vein: early: 1845 vs. 948; P = 0.047, late: 1817 vs. 953; P = 0.088). The number of bubbles was sex-dependent. Lastly, 29% of female air divers but only 14% of male divers were bubble-free (P = 0.058).Air28® helps to reduce venous gas emboli in recreational divers. The bubble number depended on the breathing gas, sampling site and sex. Thus, both exact reporting the dive and in particular standardising sampling characteristics seem mandatory to compare results from different studies to further investigate the hitherto incoherent relation between inert gas bubbles and DCS.

Heterogeneous Attitudes of Tourists toward Lionfish in the Mexican Caribbean: Implications for Invasive Species Management

Indo-Pacific lionfish (Pterois volitans and P. miles) are invasive predators established throughout the Wider Caribbean. They have already caused significant ecological impacts and have the potential to affect local economies that depend on coral reefs. Snorkeling and scuba diving are important activities that rely on aesthetically pleasant reefs. We asked whether lionfish-invaded reefs have lower aesthetic value and whether fees to help control the invasion might be acceptable to recreational divers and snorkelers in the Mexican Caribbean. To do so, we conducted a choice experiment in which tourists were asked to indicate their preferences for coral reef images with varying attributes that can be affected by lionfish. We specified a priori two classes of respondents, i.e. snorkelers and divers, but two latent classes of recreational divers (casual vs. committed) emerged on the basis of their preferences. Tourist age, commitment to snorkeling /diving, and lionfish awareness explained class membership. Casual divers and snorkelers preferred reefs with lionfish and accepted their impacts on the reefs. In contrast, committed divers disliked lionfish and associated impacts, and would elect to dive elsewhere if such impacts were high. Casual divers and snorkelers preferred options with low lionfish control fees, while committed divers were willing to pay high fees. Our results indicate potential economic impacts of the lionfish invasion in regions that depend on reef-related tourism, and that lionfish control fees might be acceptable to some but not all recreational users. However, because all tourists favored to a greater extent reef features that can be affected detrimentally by lionfish than they favored lionfish themselves, we predict that managing the lionfish invasion should be beneficial to the local reef tourism industry.

Effects of oxygen-enriched air on cognitive performance during SCUBA-diving – an open-water study

ABSTRACTBackround: Nitrogen narcosis impairs cognitive function, a fact relevant during SCUBA-diving. Oxygen-enriched air (nitrox) became popular in recreational diving, while evidence of its advantages over air is limited. Aim: Compare effects of nitrox28 and air on two psychometric tests.Methods: In this prospective, double-blind, open-water study, 108 advanced divers (38 females) were randomized to an air or a nitrox-group for a 60-min dive to 24 m salt water. Breathing gas effects on cognitive performance were assessed during the dive using a short- and long-term memory test and a number connection test.Results: Nitrox28 divers made fewer mistakes only on the long-term memory test (p = 0.038). Female divers remembered more items than male divers (p < 0.001). There were no significant differences in the number connection test between the groups.Conclusion: Likely owing to the comparatively low N2 reduction and the conservative dive, beneficial nitrox28 effects to diver performance were moderate but could contribute to diving safety.

Short- and long-term effects of diving on pulmonary function.

The diving environment provides a challenge to the lung, including exposure to high ambient pressure, altered gas characteristics and cardiovascular effects on the pulmonary circulation. Several factors associated with diving affect pulmonary function acutely and can potentially cause prolonged effects that may accumulate gradually with repeated diving exposure. Evidence from experimental deep dives and longitudinal studies suggests long-term adverse effects of diving on the lungs in commercial deep divers, such as the development of small airways disease and accelerated loss of lung function. In addition, there is an accumulating body of evidence that diving with self-contained underwater breathing apparatus (scuba) may not be associated with deleterious effects on pulmonary function. Although changes in pulmonary function after single scuba dives have been found to be associated with immersion, ambient cold temperatures and decompression stress, changes in lung function were small and suggest a low likelihood of clinical significance. Recent evidence points to no accelerated loss of lung function in military or recreational scuba divers over time. Thus, the impact of diving on pulmonary function largely depends on factors associated with the individual diving exposure. However, in susceptible subjects clinically relevant worsening of lung function may occur even after single shallow-water scuba dives.

Understanding Characteristics of Upward and Downward Flows in Coral Reef Region for Safety of Recreational Diving

ABSTRACT Jeong, Y.M.; Kim, S.G.; Lee, J.H.; Yoon, J.S., and Lee, W.D., 2017. Understanding characteristics of upward and downward flows in coral reef region for safety of recreational diving. In: Lee, J.L.; Griffiths, T.; Lotan, A.; Suh, K.-S., and Lee, J. (eds.), The 2nd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 79, pp. 35–39. Coconut Creek (Florida), ISSN 0749-0208. The goal of this study is to gain an understanding of the flow characteristics in reef regions through numerical simulations for safe recreational diving in the region. The applied numerical model was first validated to verify its feasibility and validity for carrying out the numerical simulations. Subsequently, an underwater survey was conducted in the Visayan Islands in the Philippines to model the reef region. Based on the underwater survey results, simulations were conducted in a three dimensional numerical wave tank with a model coral island. According to the numerical analysis results, stronge...

SURVEYING, MODELING AND 3D REPRESENTATION OF A WRECK FOR DIVING PURPOSES: CARGO SHIP “VERA”

Abstract. This paper presents the results from an underwater recording of the stern part of a contemporary cargo-ship wreck. The aim of this survey was to create 3D representations of this wreck mainly for recreational diving purposes. The key points of this paper are: a) the implementation of the underwater recording at a diving site; b) the reconstruction of a 3d model from data that have been captured by recreational divers; and c) the development of a set of products to be used by the general public for the ex situ presentation or for the in situ navigation. The idea behind this project is to define a simple and low cost procedure for the surveying, modeling and 3D representation of a diving site. The perspective of our team is to repeat the proposed methodology for the documentation and the promotion of other diving sites with cultural features, as well as to train recreational divers in underwater surveying procedures towards public awareness and community engagement in the maritime heritage.

Estimates of the non-market value of sea turtles in Tobago using stated preference techniques

Economic benefits are derived from sea turtle tourism all over the world. Sea turtles also add value to underwater recreation and convey non-use values. This study examines the non-market value of sea turtles in Tobago. We use a choice experiment to estimate the value of sea turtle encounters to recreational SCUBA divers and the contingent valuation method to estimate the value of sea turtles to international tourists. Results indicate that turtle encounters were the most important dive attribute among those examined. Divers are willing to pay over US$62 per two tank dive for the first turtle encounter. The mean WTP for turtle conservation among international visitors to Tobago was US$31.13 which reflects a significant non-use value associated with actions targeted at keeping sea turtles from going extinct. These results illustrate significant non-use and non-consumptive use value of sea turtles, and highlight the importance of sea turtle conservation efforts in Tobago and throughout the Caribbean region.

Effect of In-water SCUBA Diving Activities on Response Time in Recreational Divers

The purpose of this study was to examine the relationship between the performance of in-water scuba diving training activities and simple motor response time. Twenty-four students enrolled in a scuba course had their motor response times measured before and after a one hour training session. Pre- and post-dive response times were measured using an iPad application. Additionally, students were asked to complete a dive history questionnaire to determine their diving experience and health history. Statistical analysis indicated a significant training effect on response time in the recreational scuba divers F (1.00, 23.00) p =.033. The results of this study suggest that basic in-water scuba training activities may improve one's ability to elicit quicker movement responses and lead to faster cognitive processing.

Sports-related lung injury during breath-hold diving.

The number of people practising recreational breath-hold diving is constantly growing, thereby increasing the need for knowledge of the acute and chronic effects such a sport could have on the health of participants. Breath-hold diving is potentially dangerous, mainly because of associated extreme environmental factors such as increased hydrostatic pressure, hypoxia, hypercapnia, hypothermia and strenuous exercise.In this article we focus on the effects of breath-hold diving on pulmonary function. Respiratory symptoms have been reported in almost 25% of breath-hold divers after repetitive diving sessions. Acutely, repetitive breath-hold diving may result in increased transpulmonary capillary pressure, leading to noncardiogenic oedema and/or alveolar haemorrhage. Furthermore, during a breath-hold dive, the chest and lungs are compressed by the increasing pressure of water. Rapid changes in lung air volume during descent or ascent can result in a lung injury known as pulmonary barotrauma. Factors that may influence individual susceptibility to breath-hold diving-induced lung injury range from underlying pulmonary or cardiac dysfunction to genetic predisposition.According to the available data, breath-holding does not result in chronic lung injury. However, studies of large populations of breath-hold divers are necessary to firmly exclude long-term lung damage.

A Framework for Managing Diver Impacts on Historic Shipwrecks

Shipwrecks are becoming increasingly popular and, therefore important attractions for recreational scuba divers. Divers’ usage of these sites has the potential to create a range of adverse impacts on their cultural heritage values. Impacts associated with recreational scuba diving include boat anchor and mooring damage, impairment of site integrity and stability, the effects of intentional and unintentional contact with shipwrecks and artifacts, as well as divers’ exhaled air bubbles coming into contact with shipwrecks. While these consequences may not present a major threat in comparison to other human impacts, such as fishing activities, extractive industries or commercial salvage, their cumulative effect can be significant, particularly at sites where visitation levels are high. Unlike natural events such as storms, diver impacts can be controlled and managing these impacts is an important component of a heritage management strategy for any site. Heritage managers face the difficult challenge of, on the one hand, balancing divers’ access to important underwater cultural heritage sites, and on the other hand, protecting these sites. This paper outlines the causes and nature of potential recreational diver impacts on shipwrecks, briefly describing a range of management approaches that can mitigate such impacts, and presents a framework for the management of diver impacts on cultural heritage values of historic shipwrecks. The framework is designed to assist managers in deciding on appropriate management actions and priorities for particular sites.

Prevalence of dental problems in recreational SCUBA divers: a pilot survey.

Objective To determine the prevalence of dental symptoms in recreational scuba divers and describe the distribution of these symptoms on the basis of diver demographics, diving qualifications and dive conditions during the episode of dental pain.Design A survey was designed and distributed through online social media platforms dedicated to scuba diving. A convenience sample of 100 recreational divers was obtained by this method.Main outcome measures The outcome measures of interest were: diver demographics, diving characteristics (level of certification, number of dives completed), occurrence of dental problems during a dive, and details of the episode.Results Forty-one percent of the respondents experienced dental symptoms during a dive. Barodontalgia was the most frequently experienced dental symptom during a dive.Conclusion Within the limits of the small sample size and online method of recruitment, the findings of this study suggest that a high proportion of recreational divers may experience dental symptoms during a dive. It would be meaningful to ensure that dental decay and damaged restorations are addressed before a dive and that the mouthpiece design be evaluated in case of complaints of temporomandibular discomfort during a dive.

Just when you thought it was safe to go back in the water...

Prevalence of dental problems in recreational SCUBA divers: A pilot survey.