Turtle (robot)

About: Turtle (robot) is a research topic. Over the lifetime, 4750 publications have been published within this topic receiving 80450 citations. The topic is also known as: Machina Speculatrix.

Reefs since Columbus

Abstract: History shows that Caribbean coastal ecosys- tems were severely degraded long before ecologists began to study them. Large vertebrates such as the green turtle, hawksbill turtle, manatee and extinct Caribbean monk seal were decimated by about 1800 in the central and northern Caribbean, and by 1990 elsewhere. Subsistence over-fishing subsequently decimated reef fish populations. Local fisheries accounted for a small fraction of the fish consumed on Caribbean islands by about the mid nine- teenth century when human populations were less than one fifth their numbers today. Herbivores and predators were reduced to very small fishes and sea urchins by the 1950s when intensive scientific investigations began. These small consumers, most notably Diadema antillarum, were apparently always very abundant; contrary to speculation that their abundance had increased many-fold due to overfishing. Studying grazing and predation on reefs today is like trying to understand the ecology of the Serengeti by studying the termites and the locusts while ignoring the elephants and the wildebeeste. Green turtles, hawksbill turtles and manatees were almost certainly comparably important keystone species on reefs and seagrass beds. Small fishes and invertebrates feed very di⁄erently from turtles and manatees and could and can not compensate for their loss, despite their great abund- ance long before overfishing began. Loss of megaverte- brates dramatically reduced and qualitatively changed grazing and excavation of seagrasses, predation on sponges, loss of production to adjacent ecosystems, and the structure of food chains. Megavertebrates are critical for reef conservation and, unlike land, there are no coral reef livestock to take their place.

Global research priorities for sea turtles: informing management and conservation in the 21st century

Abstract: Over the past 3 decades, the status of sea turtles and the need for their protection to aid population recovery have increasingly captured the interest of government agencies, non-governmental organisations (NGOs) and the general public worldwide. This interest has been matched by increased research attention, focusing on a wide variety of topics relating to sea turtle biology and ecology, together with the interrelations of sea turtles with the physical and natural environments. Although sea turtles have been better studied than most other marine fauna, management actions and their evaluation are often hindered by the lack of data on turtle biology, human–turtle interactions, turtle population status and threats. In an effort to inform effective sea turtle conservation a list of priority research questions was assembled based on the opinions of 35 sea turtle researchers from 13 nations working in fields related to turtle biology and/or conservation. The combined experience of the contributing researchers spanned the globe as well as many relevant disciplines involved in conservation research. An initial list of more than 200 questions gathered from respondents was condensed into 20 metaquestions and classified under 5 categories: reproductive biology, biogeography, population ecology, threats and conservation strategies.

Population genetics and phylogeography of sea turtles.

Abstract: The seven species of sea turtles occupy a diversity of niches, and have a history tracing back over 100 million years, yet all share basic life-history features, including exceptional navigation skills and periodic migrations from feeding to breeding habitats. Here, we review the biogeographic, behavioural, and ecological factors that shape the distribution of genetic diversity in sea turtles. Natal homing, wherein turtles return to their region of origin for mating and nesting, has been demonstrated with mtDNA sequences. These maternally inherited markers show strong population structure among nesting colonies while nuclear loci reveal a contrasting pattern of male-mediated gene flow, a phenomenon termed ‘complex population structure’. Mixed-stock analyses indicate that multiple nesting colonies can contribute to feeding aggregates, such that exploitation of turtles in these habitats can reduce breeding populations across the region. The mtDNA data also demonstrate migrations across entire ocean basins, some of the longest movements of marine vertebrates. Multiple paternity occurs at reported rates of 0–100%, and can vary by as much as 9–100% within species. Hybridization in almost every combination among members of the Cheloniidae has been documented but the frequency and ultimate ramifications of hybridization are not clear. The global phylogeography of sea turtles reveals a gradient based on habitat preference and thermal regime. The cold-tolerant leatherback turtle (Dermochelys coriacea) shows no evolutionary partitions between Indo-Pacific and Atlantic populations, while the tropical green (Chelonia mydas), hawksbill (Eretmochelys imbricata), and ridleys (Lepidochelys olivacea vs. L. kempi) have ancient separations between oceans. Ridleys and loggerhead (Caretta caretta) also show more recent colonization between ocean basins, probably mediated by warm-water gyres that occasionally traverse the frigid upwelling zone in southern Africa. These rare events may be sufficient to prevent allopatric speciation under contemporary geographic and climatic conditions. Genetic studies have advanced our understanding of marine turtle biology and evolution, but significant gaps persist and provide challenges for the next generation of sea turtle geneticists.

Estimating the effects of road mortality on turtle populations

Abstract: Road mortality is suspected to have contributed to widespread population declines in turtles in the United States, a country with exceptionally high turtle diversity. We examined the issue through a modeling study that integrated road maps and traffic-volume data with simulated movements of (1) small-bodied pond turtles, (2) large-bodied pond turtles, and (3) terrestrial and semiterrestrial ("land") turtles. Our model predicted that road networks typical of the northeastern, southeastern, and central regions have the potential to limit land-turtle populations and, to a lesser extent, populations of large-bodied pond turtles. Nowhere are populations of small-bodied pond turtles likely threatened regionally by road mortality. We conclude that the demographic traits of some turtles, in combination with their mobility, may jeopardize population persistence within road networks typical of the eastern and central United States.