Archive for category: Uncategorized

Study site

Eilat’s unique underwater habitat is one of its major attractions and a key feature in the city’s image as a tourist destination. It would, therefore, be reasonable to assume that many of its divers are domestic and international tourists who come to the city specifically to dive, or to learn how to dive, especially since the city boasts unique natural characteristics as a diving site (Chadwick-Furman, 1995; Cole et al., 2016; Wilhelmsson et al., 1998). Diving activity around coral reefs in Eilat is high. A diving guide book for the coasts of Israel describes 14 individual dive sites in Eilat, four of which are artificial (Gur, 2004). In the 2016 Eilat Tourism Guide & Discounts circulated at the local airport and tourism centers, two of nine sites recommended for diving in the city are artificial (both are military ships that were intentionally sunk to create diving attractions). It has been reported that more than 250,000 dives per year take place on this short 13 km stretch of coastline, with the majority of these dives taking place within the confines of the Coral Beach Nature Reserve, which is less than 5 km in length (Wilhelmsson et al., 1998; Zakai and Chadwick-Furman, 2002).

The current study examines the site that may have the highest diving density in Israel, with an estimated more than 120,000 dives per year, most of them introductory and course dives (Zakai and Chadwick-Furman, 2002). The Tamar Reef was positioned near the entrance to the nearby Marine Protected Area (MPA), between a natural coral knoll of a similar size about 10 m to its south and a smaller natural knoll 10 m to its northwest (see Fig. 1). Polak and Shashar (2012) examined whether this addition decreased diving density at the nearby natural reefs. It was found that the Tamar Reef had a small, yet significant, effect on the amount of time instructional divers spent in the MPA, but mostly changed the distribution of the dives in the MPA, with novice divers spending a smaller portion of their dive time in it (see Fig. 2).

Fig. 1. Map of the study sites with the blown up map showing the position of the site within the Gulf of Aqaba (Credit: Dr. Gil Koplovitz) and the Google Maps excerpt showing the position of the three knolls (Rock 5, Tamar Reef and Rock 6) in relation to one another.

Fig. 2. Both images courtesy of Jenny Tynyakov.

The impact of scuba diving on coral reefs is highly variable, depending on the individual divers (Rouphael and Inglis, 1997, 2001). This suggests that divers’ behavior and perceptions of the environment play an important role in the impact each diver may have on the reef. Ong and Musa (2012) found that the extent of the actual impact on coral reefs is highly influenced by the diver’s experience and skill level. The diver’s attitude also influences the relationship between the diving experience and underwater behavior. Fortunately, even a short environmental awareness briefing significantly improves diver’s behavior and to lead to a reduction in contact with the reef, especially with live corals, which are severely harmed by such contact (Medio et al., 1997; Shani et al., 2012). In Eilat, the dive clubs have pre-dive briefings for all introductory diving courses and guided dives. These pre-dive briefings generally include a small amount of instruction on the local marine life and how to treat organisms underwater. Some also refer to the Tamar Reef as a sustainable method of reducing the pressure on the natural reefs. However, independent divers rent air tanks and/or other equipment from the clubs, but do not participate in a pre-dive briefing. It is rare that dive clubs brief independent divers; generally, this would only occur if the independent divers asked for information about sites.

The Tamar Reef, which is the focus of the second study, was submerged in October 2006 in the area with the highest diving density in Israel, as well as the highest number of instructional dives (Rouphael and Inglis, 1997). It was developed by the Israel Nature and Parks Authority, Ocean Bricks Systems, and academics from Ben-Gurion University at Eilat, the Inter-University Institute for Marine Sciences, the Hebrew University of Jerusalem, and the Marine Science Station in Aqaba, Jordan. Made from special concrete, suitable for the settlement of marine invertebrates, and studded with drilled holes in which nursery-grown corals were planted, the Tamar Reef was carefully designed to appeal both to divers and to marine animals in the area. Since 2012, there has been no active coral planting on it, yet it still demonstrates a high amount of natural coral settlement. The proximity of this site to the Coral Beach Nature Reserve, a MPA, was also a critical consideration in selecting the location. Initial examination of the effectiveness of the Tamar Reef indicates that it had a small yet significant effect on the amount of time instructional divers spent in the marine reserve, and on the distribution of dives in the marine reserve (Medio et al., 1997; Polak and Shashar, 2012; Schleyer and Tomalin, 2000). From a pragmatic point of view, the conceptualization of authenticity suggested here is an important step towards using artificial reefs as a conservation tool in other scuba diving destinations (Shani et al., 2012).

First study

The purpose of this study was to compare the popularity of diving sites along the coast of Eilat, Israel. Information was gathered from divers of different levels between October and December 2016. The duration of time between the first and last responses to the online survey received was 56 days. Participants were asked to list the diving sites and to respond to a set of questions published via the software and website. A request for respondents was sent out via Facebook to a closed group of Israeli divers called, “the diver’s wet house in Israel”. This Facebook group has about 6700 subscribers, mostly from Israel. The users were encouraged to send out the questionnaire to other divers whom they knew might not be part of the Facebook group. A pilot study was conducted prior to the online questionnaire being sent out. Thirty divers were asked to complete the questionnaire and provide feedback. Based on their suggestions, changes were made that improved the clarity of questions in the questionnaire.

The data was collected using SurveyMonkey⁽™⁾. There were 10 questions in the survey. The first was an open-ended (qualitative) question. The other nine were closed response type questions, but also sought open-ended comments. The demographics section made up six additional questions, all of which were quantitative in nature. The software provided a response count, a response percentage, and qualitative data. The raw data was downloaded from the software into a Microsoft Excel spreadsheet. The qualitative data were analyzed using descriptive statistics for verification and mean scores were derived for all quantitative results.

Second study

Data were collected on scuba divers near three knolls in Eilat, Israel (29°32?85?N, 34°57?47?E), which are located at the main diving training beach in Eilat. This beach is also home to three major diving clubs and used by many others (Fig. 1). Detailed data on divers’ behavior were collected over a cumulative period of 28 h during the high diving season of September 2015. These surveys were performed by two people snorkeling above the sites. This was done because following divers by snorkeling reduced the chance of them noticing or paying attention to the researchers and, thus, did not affect the divers’ behavior as much. The observations were performed for an hour at a time, with each snorkeler spending 20 min at each of the three knolls per session. There were never two snorkelers at the same knoll simultaneously.

The three knolls reside within a few meters of one another on the edge of the Coral Beach Nature Reserve in Eilat. The first, Rock 5, is a smaller natural knoll found at a depth of 5 m. It has been degraded over time and appears to host less diverse marine life than the other two knolls. The second is the Tamar Reef, described above. The third knoll, Rock 6, is a larger natural knoll found at a depth of 6 m. Rock 6 is more similar in vibrancy, diversity, and size to the Tamar Reef than Rock 5.

Observations took place from mid-morning to late afternoon (between 10:00 and 15:30) to coincide with the highest amount of diving activity of the day. The surveyors spent 20 min observing divers at each of the three knolls. The first knoll observed was chosen at random, as was the direction of rotation to the different knolls. The time of arrival of divers, duration of stay, type of divers, number of divers in the group, and presence of photographers were recorded, as well as the divers’ behavior. Divers were classified as follows: (1) Introduction divers – People who have never dived before and are being introduced to the reef by a guide. These divers are usually closely supervised by the guide and limited to a depth of 6 m; (2) Independent divers – People with scuba diving qualifications that are diving without a guide; (3) Guided divers – People with scuba diving qualifications that are diving with a guide, often in a group; (4) Course divers – People participating in a diving course and diving with an instructor as part of the requirements and training of this course; and (5) Photographers – People diving purely for the purpose of underwater photography and carrying larger cameras (not including GoPro cameras) and generally having more gear with them.

A main part of the observation was to record the behavior of the divers around the knolls, particularly behavior that is detrimental to coral. It was also noted whether the divers were carrying cameras or not. Behavior categories comprised: (1) Touching with hands (either intentionally or by accident); (2) Kicking with fins – Divers kicking the knoll with their fins; (3) Kicking up sand – Divers stirring up sand around and/or onto the knoll; (4) Touching with a camera – Divers touching the knoll with their photography gear, especially those placing their cameras on the knolls to take photographs; (5) Touching with a tank – Divers swimming too close to the knolls and scratching the corals with their scuba tanks; (6) Dragging of gauges – Divers swimming too close to the knolls and scratching the knolls with their pressure gauges or other equipment that is hanging beneath them.

Data were analyzed using MS Excel™ and R (R i386 3.2.3 using RStudio™) software. Shapiro-Wilkes tests were run to check the normality of all dependent variables per knoll. Levene’s tests were run to check the homoscedasticity of the dependent variables as a whole. A variable called “diver minutes” was calculated to standardize the amount of time spent by each diver across all the knolls. The number of divers in a group was multiplied by the amount of time each group spent at the knoll. For instance, a group of three divers that spent 2 min at a knoll will amount to six diver minutes for that knoll. The average number of divers per minute was calculated by dividing the diver minutes per survey by 20 (the number of minutes per survey). The average number of divers per hour was calculated by multiplying the diver minutes per survey by three. An ANOVA and a post-hoc Tukey test were performed on the average number of divers per minute per knoll.

The average number of events per diver was calculated by dividing the total number of divers observed during a survey by the number of observed contacts with the knoll during that survey. A permutational ANOVA test, with a maximum of 10,000,000 iterations and a p-value sensitivity of 0.001, and a post-hoc pairwise permutation test were run on the average number of events per diver per knoll. The diver composition was calculated by dividing the number of divers of each type at each knoll by the total number of divers at that knoll. The percentage of damage per type of diver was calculated by dividing the number of contacts per type of diver at each knoll by the total number of contacts at that knoll.

A Pearson’s chi-squared test with the Yate’s continuity correction was run to test the association between a diver carrying a camera and making contact with a knoll. This test was run for all knolls overall and for each knoll separately. The composition of events was calculated by dividing the number of contacts of a certain type at each knoll by the total number of contacts at that knoll.

Third study

Questionnaires were set up to gauge the self-perceived behaviors of divers when diving and their attitudes towards different types of reefs. These questionnaires were distributed at diving conferences in Israel during September 2015, as well as online in both local and international diving forums. The total number of completed questionnaires was 311. Online questionnaires were downloaded and imported into SPSS™. Written questionnaires were transcribed into digital values and then imported into SPSS™. Descriptive statistics of the key questions were performed in SPSS™ and tabulated in MS Excel™.

First study

Second study

The attractiveness of the Tamar Reef was measured through the average number of divers observed per minute at Rock 5, Rock 6, and Tamar. The average number of divers per minute, which is defined here as “diver density,” at the Tamar Reef is the highest, at 3.06 divers per minute. The diver densities at Rock 5 and Rock 6 are 2.24 and 2.55 divers per minute, respectively (Fig. 3).

1. Download high-res image (135KB)
2. Download full-size image

Fig. 3. Diver density at the Tamar Reef is significantly higher than that at Rock 5 (ANOVA: F2, 81=2.487; p = 0.0895). However, the diver density at Rock 6 is not significantly different from either Rock 5 or the Tamar Reef (p > 0.1). These differences are denoted in each of the bars by the letters “a” and “b”. If there is no significant difference between two bars, they are assigned the same letter.

The effectiveness of the Tamar Reef is operationalized here with the average number of disturbance events per diver at each of the three knolls (Fig. 4). A disturbance event is defined here as any contact – direct or indirect – between divers and the knolls. All such contact can potentially be damaging to the knolls. The average number of disturbance events per diver at the artificial reef is significantly higher than at the other knolls, leading to a result of approximately one event per minute at the artificial reef vs. approximately 0.5 events per minute at the natural reefs. The Tamar Reef has significantly more events per diver on average (0.338 events per diver), while Rock 5 and Rock 6 have almost the same average number of events per diver (0.212 and 0.209 events per diver, respectively). The average number of events per diver at the Tamar Reef is significantly different from that at Rock 5 and at Rock 6 (Iterations = 10,000,000, df = 2, 81, p < 0.1). In this context, it is noteworthy that, not only does the Tamar Reef have more divers and more events per diver, but these events are also more severe, i.e. events that involve direct contacts, such as fin kicks and hand touches. Direct contact events at the Tamar Reef make up almost 78% of all events there, compared to only 30–40% at the examined natural reefs (Rock 5 and Rock 6). This leads to the conclusion that the artificial reef is effectively diverting divers and diver pressure from these natural knolls, and is, in turn, suffering more severe damage from divers.

1. Download high-res image (129KB)
2. Download full-size image

Fig. 4. Rock 5 and Rock 6 do not have a significant difference in the average number of disturbance events per diver (p = 0.97). These differences are denoted in the chart by “a” and “b”. If there is no significant difference between two bars, they are assigned the same letter.

The third way the difference between the three reefs was measured was by comparing the type of divers at them. As noted above, the five types of divers observed at the knolls were: (1) Introduction divers – People who have never dived before and are being introduced to the reef by a guide; (2) Independent divers – People with scuba diving qualifications that are diving without a guide; (3) Guided divers – People with scuba diving qualifications that are diving with a guide, often in a group; (4) Course divers – People participating in a diving course and diving with an instructor as part of the requirements and training of this course; (5) Photographers – People diving purely for the purpose of underwater photography. Overall, the composition is quite similar at all three knolls and indicative of a diving training area. Between 60% and 70% of all the dives at all the knolls are ‘intro’ dives for non-qualified divers, with Rock 6 having the highest proportion of intro divers (Fig. 5). Course dives to train new divers make up 18%–25% of the diver composition at all three knolls. Rock 5 has the highest proportion of course dives – 24.23%. Independent dives make up 7%–10% of all dives at the three knolls. The Tamar Reef has a 10.11% proportion of independent dives. Guided dives for qualified divers make up the lowest percentage at all three knolls, with only between 2% and 4% of all dives being guided dives (Fig. 5). Only two professional photographers were observed during the surveys. These two photographers were observed at the Tamar Reef, and make up only 0.32% of the total divers observed.

1. Download high-res image (250KB)
2. Download full-size image

Fig. 5. Diver composition at three knolls.

Of all the recorded diver contacts with the reef knolls, intro divers are the major culprits at the Tamar Reef and at Rock 5 (64.38 and 62.31% of all contacts, respectively; see Fig. 6). On the other hand, the intro divers are only the cause of 36.17% of the contacts or damage at the southern Rock 6, where independent divers caused 38.30% of the damage. The percentage of damage caused by independent divers at the Tamar Reef and Rock 5 is much lower (23.13 and 11.54%, respectively). Course divers are the cause of a fair percentage of the damage at Rock 5 and Rock 6 (23.84 and 23.40%, respectively). Guided dives result in a minimal percentage of damage, with only approximately 2% of all damage at all three knolls being as a result of guided dives (Fig. 6). The least detrimental of all divers in this sample are the professional photographers who had no contact with the knolls whatsoever (Fig. 7). It is, however, important to remember that there were only two professional photographers observed throughout the survey.

1. Download high-res image (285KB)
2. Download full-size image

Fig. 6. Damage per type of divers.

1. Download high-res image (512KB)
2. Download full-size image

Fig. 7. Composition of disturbance events.

The low percentage of damage inflicted by course divers in all three knolls is surprising (4). Course divers inflicted only between 10 and 24% of the damage, although they made up 18–25% of the divers surveyed. One explanation is that course divers are monitored by their instructors. Another explanation, as suggested by Rouphael and Inglis (26), might be that less experienced or novice divers are usually more cautious.

As noted above, the damage caused by divers is defined here as a disturbance event, which is further categorized into six types of event (see methods and Fig. 7: (1) Touching with hands; (2) Fin kicking; (3) Stirring up sand; (4) Camera touching; (5) Dive tank touching; and (6) Dragging of gauges. There is a much higher proportion of divers that touch the Tamar Reef with their hands and kick it with their fins (77.44% of the total events at Tamar) than at the other two sites – Rock 5 and Rock 6 (33.59% and 39.36% of the total events per reef, respectively). On the other hand, more divers kick up sand around and onto Rock 5 and Rock 6 (60.31% and 54.26% of the total events per reef, respectively). Therefore, direct contact events (via hands and fins) are more prominent at the artificial reef and indirect contact events (kicking up sand) are more prominent at the other two natural knolls. The percentage of loose equipment dragged across the corals is similar at all the knolls (approximately 5% – which is an indication of inexperience and, therefore, can be considered unintentional damage). A small percentage of divers touch the knolls with cameras (1% and less at all three knolls) and an even smaller to insignificant percentage touch the knolls with their air tanks (only Rock 5 was touched with a tank – 0.76% of the total events at Rock 5).

Third study