Comparison of the diets of sympatric dugongs and green turtles on the Orman Reefs, Torres Strait, Australia

André, Jessica; Gyuris, Emma; Lawler, Ivan R.

doi:10.1071/wr04015

Cited by 59 publications

(47 citation statements)

References 22 publications

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“…The results were collated with those reported in the literature, and a species list of potential green turtle forage for Rota was compiled along with locations and references. Hirth (1997) and additional sources (Agastheesapillai and Thiagarajan 1979, Balazs 1980, 1985, Mortimer 1981, Mendonca 1983, Balazs et al 1987, 1995, Burke et al 1991, Limpus et al 1994, Forbes 1996, Russell and Balazs 2000, Read and Limpus 2002, Seminoff et al 2002, Calvo et al 2003, Ferreira et al 2003, LopezMendilaharsu et al 2003, Russell et al 2003, Searle 2003, Andre et al 2005 Figure 1). No other turtle species were encountered.…”

Section: Methodsmentioning

confidence: 99%

Nearshore Distribution and an Abundance Estimate for Green Sea Turtles, Chelonia mydas, at Rota Island, Commonwealth of the Northern Mariana Islands

Kolinski¹,

Hoeke²,

Holzwarth³

et al. 2006

Pacific Science

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Seventy-three green turtles, Chelonia mydas (Linnaeus, 1758), were observed in 84 sightings along 28 transects covering 67% of Rota's shoreline and outer reef perimeter in the Commonwealth of the Northern Mariana Islands. No other sea turtle species were encountered. Juvenile turtles of various sizes dominated in all surveyed environments, and observations of turtles with estimated straight carapace lengths a 40 cm suggested recent and continuing recruitment at Rota. Distribution of turtles appeared temporally stable when compared with previously reported observations and data, with turtle concentrations highest along northeast, east, and southeast coasts of the island. Approximately 118 turtles were projected to inhabit nearshore habitats at Rota. Although this population may appear minor and indistinct compared with those at nearby Tinian and Saipan, continued monitoring would be useful for comparison of Mariana Islands trends. Thirty-five species of cyanophytes, algae, and a sea grass noted as green turtle forage in other world regions were identified at Rota in this and previous surveys.

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Section: Methodsmentioning

confidence: 99%

Nearshore Distribution and an Abundance Estimate for Green Sea Turtles, Chelonia mydas, at Rota Island, Commonwealth of the Northern Mariana Islands

Kolinski¹,

Hoeke²,

Holzwarth³

et al. 2006

Pacific Science

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“…and dugongs (Lanyon et al, 1989;André et al, 2005; cf. simulation study by Aragones and Marsh, 2000); so it is doubtful whether they compete significantly with dugongs or manatees at the present time.…”

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confidence: 99%

Use of tusks in feeding by dugongid sirenians: Observations and tests of hypotheses

Domning

Beatty

2007

The Anatomical Record

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Most living and fossil sea cows of the subfamily Dugonginae (Dugongidae, Sirenia, Mammalia) are characterized by large upper incisor tusks, which are thought to play an important role (at least primitively) in feeding on seagrass rhizomes. Testing this hypothesis is difficult, because the only extant tusked sirenian (Dugong dugon) is morphologically and perhaps behaviorally aberrant. The tests attempted here involve examination of stomach contents of wild Recent dugongs, experiments using plastic replicas of diverse tusks to harvest seagrasses, gross anatomical observations on tusks and skulls, measurements of tusk tip geometry, and observations of microwear on tusks. We conclude that (a) male D. dugon (with erupted tusks) do not consume more rhizomes than females (without erupted tusks); (b) the tusks do not play a significant role in feeding in the modern dugong; (c) larger, more bladelike tusks are more effective at harvesting rhizomes, but the effect of shape was not experimentally separated from the effect of exposed tusk length; (d) some fossil dugongines show apparent cranial adaptations for downward and backward cutting motions of their large, bladelike tusks; (e) geometry of wear surfaces is consistent with use of at least the more bladelike tusks as cutting instruments; (f) preliminary observations of microwear in D. dugon do not indicate more than occasional use of the tusks in purposeful harvesting of rhizomes, and then only opportunistically by large adult males. The hypothesis of such tusk use by extinct dugongines (in contrast to the living species) is so far corroborated, but available data and tests do not suffice to establish this conclusively. Anat Rec, 290:523-538, 2007Rec, 290:523-538, . 2007 Wiley-Liss, Inc.Key words: Sirenia, Dugongidae; Dugong dugon; tusk; feeding; seagrass rhizomes; stomach contents; dental microwear A quantitatively significant but poorly understood aspect of mammalian history is the long relationship between herbivorous marine mammals and the plants they have eaten. This history extends over the 50 million years of the fossil record of these mammals (mainly those in the Order Sirenia: dugongs and manatees), and chiefly involves the tropical-to-temperate, cosmopolitan marine angiosperms or seagrasses (Hydrocharitaceae and Potamogetonaceae), which today constitute one of the Earth's most productive ecosystems, as has presumably been true throughout the Cenozoic (Ivany et al., 1990). The greatly diminished diversity of modern sirenians, however, is a major obstacle to exploring how feeding adaptations, niche partitioning, and other

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“…Where the density of green turtles is very high, green turtles may even overgraze seagrass meadows causing habitat degradation (Christianen et al, 2014). However, at some coastal foraging sites green turtles may also consume macroalgae such as in parts of the Torres Strait, Australia (André et al, 2005). Macroalgae may even dominate their diet, for example in some areas of the eastern Pacific (Seminoff et al, 2002).…”

Section: Case Study: Green Sea Turtles and The Great Chagos Bankmentioning

confidence: 99%

New Tools to Identify the Location of Seagrass Meadows: Marine Grazers as Habitat Indicators

et al. 2018

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Comparison of the diets of sympatric dugongs and green turtles on the Orman Reefs, Torres Strait, Australia

Cited by 59 publications

References 22 publications

Nearshore Distribution and an Abundance Estimate for Green Sea Turtles, Chelonia mydas, at Rota Island, Commonwealth of the Northern Mariana Islands

Nearshore Distribution and an Abundance Estimate for Green Sea Turtles, Chelonia mydas, at Rota Island, Commonwealth of the Northern Mariana Islands

Use of tusks in feeding by dugongid sirenians: Observations and tests of hypotheses

New Tools to Identify the Location of Seagrass Meadows: Marine Grazers as Habitat Indicators

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