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Findings of the Observations in situ of Tortuga Chelonia mydas
Akumal Bay, Quintana Roo, Mexico
by Sheldon I. Aptekar

Weather conditions in Akumal Bay from 03 to 13 August 2000 were poor, resulting in one hour and thirty five minutes of logged turtle observations. Often the water was turbulent due to approaching storms and winds. The summer before, 05 to 12 August 1999, over eleven hours of turtle observations were logged. In prior observations made from 31 July- 21 August 1998, and from 01 - 07, & 12- 19 August 1997, an additional seventy hours were logged. (See note #1)
The initial sightings and observations were verbally reported to the Director of the Turtle Project, Luis Manuel Ortiz or the staff at the Centro Ecologico Akumal. The 1998 observations and sightings were transcribed in notebooks at the end of the day and later typed. Subsequent notations in 1999 and 2000 were recorded in situ on an underwater writing tablet, daily rewritten in notebooks and then at a later date typed.
Depending on lighting, weather conditions and water depth, photographs were taken to support observations. The photographs taken in 1997 with a Kodak underwater throwaway camera were processed in Mexico and then left for Ortiz at the Center. Those photographs were of poor quality and are now considered to be missing. The photographs of the turtles observed during the summer of 1998 were processed in New York. A set of twenty-four photographs of those turtles were sent to Ortiz via Michael Mulgrew in Canada to assist in the Center's on-going research of Chelonia mydas. (Mulgrew is the Director of the Centro Ecologico Akumal.) In 1999 and 2000 an additional thirty-one photographs were taken. There are a total of fifty- five turtle photographs taken in situ over a three year period. The equipment used for the photographs in 1998, 1999 and 2000 was a "Bonica Snapper" which houses a Vision XMS auto flash, focus free, point and shoot camera without a filter. The housing for the camera is rated to withstand 160 feet of water pressure. Film used was either Kodak or Kirkland ASA 400 for color prints.

Each observation in the report was listed as to date, time of day, location, activity, and, any outstanding conditions. The observer used snorkel gear and limited "skin dives" as not to disturb the turtles or the environment.

During the four observation periods, both tagged and untagged turtles were observed. (Some turtles had both the tag on the front left flipper and a living mark on its carapace, while others had only a visible living mark. See Photographs '98 #3, #11, '99 #5, #8, and '00 #8, #9.) Turtle size varied greatly with more mature turtles seen in 1997 than at any other time. According to information provided by Ortiz and then by Alejandro Arenas (from the Foundation to Save Sea Turtles at Xcaret) the living tagged turtles came from at least two different locations, X'cacel and Xcaret. (See notes #2 Ortiz e-mail and Arenas' "Living Tag Project" Chart.) Of particular interest was the fact that Akumal Bay had a number of nesting areas and, it appeared that the turtle hatchlings remained in the bay to feed.
According to Mr. Ortiz the transcribed turtle behavior and the photographs were of interest not only to him but to researchers working at Xcacel and Xcaret where the turtle tagging program was being coordinated. The fact that tagged turtles had been found in Akumal Bay with unmarked turtles was noteworthy. Ortiz, and then Jesus Rosiles Nieto (who replaced Ortiz at the CEA) and Arenas indicated that the observations and photographs seemed to modify the concepts of the "lost years" developed by Archie Carr. (See notes #3)

In February 1999, a project to record turtle behavior in Akumal Bay with a series of videos was planned. The video studies were to be the first in the Mexican Caribbean (See note #4). The video project, however, was delayed, for by the spring of 2000 the Centro Ecologico Akumal had to focus its resources on proper methods of sanitation. . It was feared that inadequate disposal methods for the entire area would destroy the bay. (See note #5).

Turtles seen during the summer of 2000 were not as large as those seen previously. None of the turtles observed in 2000 had Remora attached to them as had those in previous years. (see photographs '98 #4, #21 and, #23, and, '99 #1, #3, #4, #6 and #7.) Whether this indicates a change in grazing pastures or swimming area is unknown to this observer. It was, however, clear that the turtles seen August 2000 were more nervous and feeding in pastures further south in the bay than in the previous three years. In August 1999 the northeast area of the bay between the promontory with the religious icon and the stairs up to the "casitas" had more algae. At times, this area had an unhealthy odor. In 2000 the bay seemed healthier. There were abundant fish, many turtles, and the plant life appeared to be healthier. In addition to Coral, Grunts, Parrot, Needle, Damsels, Jacks, Sergeant Major, Striped Angel, Flounder, Blenny, Barracuda, Grouper, Palometa, and Ballyhoo, and the occasional octopus, the plant life previously observed included the grasses, grooved blade sea whip, flat top bristle brush, and mermaid's fan. In the summer of 2000, there were Cuttle fish, a variety of rays, and several bass.

In the third year (1999) of observations, Akumal Bay had a noticeable change in sea life. Turtle grass was more abundant than in prior observation periods and there seemed to be fewer fish. Grunts, Parrot fish, Needle fish, Damsels, Jacks, Sergeant Major and Striped Angel were present, but fewer. Schools of small silver fish, Sardines(?), were also seen in the warm shallow water, hiding in the turtle grass, but, there were fewer fish in the schools. As mentioned, the water in the northeast corner of the bay had, at times, a slightly putrid odor and there seemed to have been more algae in that part of the bay than in 1998 and 1997.

In 1997 and 1998, the northeast corner of the bay had many fish, including Flounder, Blenny, Barracuda, Palometa, and Ballyhoo swimming near the reef and in shallower water. Turtles would graze in this area for extended periods, and in August, 1998 this was the dominant observation location. In the fall of 1998, Ortiz commented about the after effects of Hurricane Mitch and the "...state wide bleaching event in the coral reef...." for which there was no explanation. Ortiz thought the hurricane and the bleaching would have direct effects on the life in the bay. In August of 1999, the northeast corner of the bay had fewer fish and the turtles only grazed there on occasion.

In 1997 and 1998, the area southwest of the Akumal Dive Shop, was, as one snorkeled out to deep water, where one could see fast moving small turtles in size from five to nine inches carapace length. Also visible were Blenny, Wrasse, Ballyhoo, long- spine urchin, Yellow Snapper and octopus. Rooted to the sea floor was the grass, purple fan coral, grooved blade sea whip, flat top bristle brush, and mermaid's fan. In August of 1999, the turtle grass was denser than ever: no flat top bristle brush or mermaid's fan was seen, nor small turtles or octopus. This does not mean these plants and animals were not in the bay, but they were not where they had been seen before.

In August of 1999, the majority of sightings and observations of the turtles were located further from shore in an area less frequented by humans. Indeed, in August, 2000 the turtle observation area moved even further to the southwest in the bay. Except as noted, the turtles observed over the past four years grazed in proximity to each other. Usually two medium sized or smaller turtles grazed near each other and a third or fourth larger turtle grazed further off. (See Photographs '98, #6, #7, #12, #13, and Photographs '00, #4, #5.) The larger turtles were in proximity to the smaller turtles. No very small turtles were observed feeding near meadows with the larger turtles. Very small turtles (palm size up to nine inches) were seen moving in shallow water in thick turtle grass. On the other hand, turtles 14 inches and larger were often observed relatively near other turtles and on occasion, actually grazing at the same spot, and, traveling with one another.

It was evident from the observations that the turtles would tolerate the presence of an observer as long as they were not threatened. Any jarring or sudden movement, splashing, and noise resulted in an evasive reaction from the turtles. Any attempt to initiate a touch resulted in the turtle moving away. At times, the turtles themselves would approach the observer and allow a touch. In 1998, a rather large unmarked turtle who had been observed for some time, dived beneath the observer and came up between his legs and literally gave him a ride of approximately 15 feet. This action was a totally unexpected one time experience. It appeared that the turtle knew what it was doing, and after the ride looked at the observer and returned to its grazing.

Over the four observation periods some common turtle behavior was noted. For example:
large turtles often shared a grazing area with a smaller turtle. Characteristic eating activities included the use of front flippers and claws (which are dominant) to clean or dust the sandy area in front of the turtle. Once the area was cleared, a turtle selected a particular stalk of grass. (At times the turtle picked a thin round stalk of grass [syringodium filiforme] from a field of wide turtle grass.) In each of the turtle's eating sequences, the turtle repeated the same actions and bit off the grass close to the root with a right headed side movement. Often when selecting grass, the turtle would clear with flippers, poke its head into the grass, and clear again before biting with a right or left sided head movement. When chewing, the turtle would extend its head out and upward as if to assist in swallowing a particularly large clump of grass. (See Photographs '98 #4, #6, #8, #10, and '99 #12, #18.) The actual sound of the turtle biting the grass and chewing could be heard. (See note #8)

While leisurely grazing, turtles appeared to move in a circular pattern about the feeding area. In addition, turtle avoidance movement or evasive actions appeared to be curved, first in one direction then another (clockwise or counter clockwise) as well as, high and low in the water until out of reach. Larger turtles tended to move in arcs eventually traveling into deep water while small turtles attempted to hide in dense turtle grass. Occasionally, turtles would appear to approach the surface for air and then abruptly move off at an acute angle to its original path and then change into a curved movement pattern. All turtles observed were able to move directly toward an object but tended to vary movement pattern. A condition affecting turtle behavior was water temperature: small turtles tended to stay in warm, shallow water within dense turtle grass, while large turtles tended to favor the cool deep water above the turtle grass. It is of note that in the deeper water, currents flowed into the warmer water of the bay. At these junctions the turtles, and, indeed, many fish would feed.

A unique event occurred one afternoon in 1999 when a turtle called "R3" (for it had a chip on its marginal scute at that location; See photographs '99, #8, & #9), selected wide blade grass from a circular area near the periphery of a Semi sandy depression. The location of this grazing meadow was at the edge of a clear sandy area on the shore side of the white reef marker southwest of Hotel Ventura.

[In its eating process that day, R3 favored its left side by chewing off a selected blade on the left and moving its head to center and back to left as it chewed and ingested. At times, R3 used its left flipper and its claw to assist in moving the grass into its mouth and to break off pieces of grass. (See Photographs '99, #18.) R3 alternated eating tall blades of grass, which it would chew off at about one inch from the sand, with new growth stubs of grass. ]

In its grazing, R3 continuously returned to a center location, ate a few blades and then went off in a circular pattern. Once it completed a circle of grazing, it returned to its center spot and started a different circular pattern. This spot, approximately 2 feet wide by 3 feet long, was oblong in shape and had a slight depression in the middle. The turtle would position itself in the center of the spot matching its oval shape proportionally to the spot. Around the spot was a mixture of grass and in it lay two pieces of broken dead branch coral. The turtle's movements from the center spot was as if it traveled along a radius to a point on the circle and then continued on the circumference until it finished its grazing. It would then return to center, travel along a different length radius and repeat the action. The movements were in no way a geometric circle but varied in shape; at times the pattern was elliptical, or oblong.

After surfacing for air, R3 would change its location on the circle but continue its grazing pattern. As observed, R3 was hesitant to go directly to the surface for air. Instead it approached the surface, rapidly plunged off to its left side, and, then darted straight up for air and quickly dived off to the right of its previous location. It then moved rapidly, just above grass height, back to its position either in the center of the feeding circle or to a position on the circle. The entire action took under a minute to complete.

R3 was aware of the observer having approached him close enough to touch more than a dozen times. The approach was always after a feeding sequence and prior to air intake. Twice while feeding, the turtle drifted beneath the observer and the hanging note pad touched its shell. At the touch, the turtle darted two to four feet to the left and then gradually returned to its position.

Fish activity was noticeable with many Needle, Grunts, Jacks, Parrots, Gray with pink fin, Blue/Gray with blue dots on tails, and small Grouper moving about in the cooler water south of the area. French Grunts were actively feeding near R3's feeding area.

When R3 would return to its slight depression in the middle of its center spot, the Grunts would cross over from the dense turtle grass and remain on the periphery of the turtle's space. Then a French Grunt would cross into the circle and sidle up parallel to and behind R3s head. The Grunt would wait for the turtle to be at rest and then nibble at the turtle's shell just in front of the front flipper. The nibbling was carried out by only one Grunt at a time, and, whether or not it was the same Grunt each time, is unknown. Once the activity was finished the Grunt would sidle away from the turtle and rejoin the others, first just outside the spot and then further away in the dense grass. None of the other fish in the area exhibited similar behavior. Although this was the first time this activity was observed, it was not a solo action, but a repeated activity, recurring throughout this observation.
Toward the end of the observation period as the turtle moved in its grazing arc, it began to graze closer and closer to the observer. At times, as noted above, it grazed directly beneath the observer. Perhaps the shadow of the observer, like that of a boat, provided the turtle with a safe feeding location.

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