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  • 1
    Electronic Resource
    Electronic Resource
    The nesting of the Pacific ridley turtle Lepidochelys olivacea on Playa Nancite, Costa Rica (1974)
    Springer
    Marine biology 24 (1974), S. 97-107 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A study of the nesting of the Pacific ridley turtle Lepidochelys olivacea was undertaken in Costa Rica on Playa Nancite — one of two beaches on which the authors had, the previous year, discovered large nesting aggregations of this species. During the 3 1/2-month period of this study, approximately 288,000 turtles nested on the 1300 m-long beach. About 99% of these nested during 3 periods of mass-nesting (arribadas). The predictability of the arribadas was investigated by observing and recording environmental parameters with which they may be correlated. The mass-nesting phenomenon, aspects of nesting behavior, and the adaptive advantages of mass-nesting are discussed. During the period of study, nearly 2,000 turtles were tagged, 102 of which were subsequently recovered. Carapace lengths and widths of 251 tagged turtles were measured. The emergence of hatchlings was recorded daily and, from these data, the incubation period and an indication of egg and hatchling survival was obtained. The activities of the various predators on eggs, hatchlings, and adults are described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00389343
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Some observations of sea turtle nesting activity in Costa Rica (1972)
    Springer
    Marine biology 16 (1972), S. 297-309 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Low level aerial observations were used to obtain synoptic records of the distribution of sea turtle nesting activity along both coasts of Costa Rica. Pertinent environmental information was simultaneously recorded including beach characteristics, river effluents, and evidence of coastal currents. Other correlative information was obtained from detailed maps, current charts, and climatological data. On the Caribbean coast, as expected, green turtle (Chelonia mydas) nesting was concentrated on the beaches between the Tortuguero and Parismina Rivers. On the Pacific coast, two major nesting beaches for the Pacific ridley Lepidochelys olivacea were found, each having over 100 thousand turtles aggregated offshore during the peak period between September and November. Aggregations were present at least from July through December. Massed nesting occurs each year on these same beaches and the event is known as the “salida de flota” by the natives of Guanacaste Province. Numerous less important nesting beaches were also found. Nesting density did not correlate well with beach quality but, instead, appeared to be related to the proximity of the beach to offshore currents. Oceanic current systems apparently facilitate the transport of sea turtles to the general vicinity of the important nesting beaches on both coasts of Coata Rica.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00347753
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Shark attraction using a video-acoustic system (1969)
    Springer
    Marine biology 2 (1969), S. 264-276 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An underwater television system located off Bimini, Bahamas, was used to observe and record the attraction of free-ranging sharks to a nearby sound source. Several species of sharks were attracted by irregularly pulsed signals either containing harmonics (e.g., overdriven sine waves) or consisting of octave bands of noise. Irregularly pulsed, pure tones and harmonic sounds above 1000 Hz were apparently not attractive. Attraction was not reinforced, and habituation of the approach response was regularly observed in prolonged test series. As the number of sharks in the test area increased, swimming activity rose dramatically. Circling and crisscrossing of the site became more intense under conditions of low ambient light and turbidity. Additional tests showed that minimum attractive sound levels were remarkably low, and that sharks could locate a sound source within seconds from distances beyond our limit of visibility (about 25 m).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00351149
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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