Rivas, M., Santidrián Tomillo, P., Diéguez Uribeondo, J. and Marco, A. Leatherback
hatchling sea-finding in response to artificial lighting: Interaction between
wavelength and moonlight.
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| © Dawn Witherington | DrawnbyDawn.com |
Over the
last decades, growing human populations have led to the rising occupation of
coastal areas over the globe causing light pollution. For this reason, it is
important to assess how this impact threatens endangered wildlife. Leatherback
turtles (Dermochelys coriacea) face many threats of anthropogenic origin
including light pollution on nesting beaches. However, little is known about
the specific effects. In this study we studied the effect of different light wavelengths
(orange, red, blue, green, yellow and white lights) on hatchling orientation under
the presence and absence of moonlight by analyzing: (i) the mean angle of
orientation, (ii) crawling duration, and (iii) track patterns. Hatchling
orientation towards the sea was always better under controlled conditions. In
the absence of moonlight, leatherback hatchlings were phototaxically attracted
to the experimental focus of light (misoriented) for the colours blue, green,
yellow and white lights. Orange and red lights caused a lower misorientation than
other colors, and orange lights produced the lowest disrupted orientation
(disorientation). On nights when moonlight was present, hatchlings were
misorientated under blue and white artificial lights. Crawling duration was low
for misoriented hatchlings and high for the disoriented individuals. Our
conclusion to this is that hatchlings can detect and be impacted by a wide
range of the light spectrum and we recommend avoiding the presence of
artificial lights on nesting beaches. Additionally, actions to control and
mitigate artificial lighting are especially important during dark nights when
moonlight is absent
Journal of
Experimental Marine Biology and Ecology 463 (2015) 143–149
Dornfeld, T, Robinson, N. J, Santidrián Tomillo, P., Paladino, · Frank V. Ecology of
solitary nesting olive ridley sea turtles at Playa Grande, Costa Rica
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| © Dawn Witherington | DrawnbyDawn.com |
Olive ridley turtles (Lepidochelys olivacea) have
two distinct mating systems: independent (solitary) and synchronized and mass
assemblages (arribadas). Arribada nesting beaches have been the focus of most
research, even though solitary nesting is the most common behavior. The purpose
of this study was to assess the contribution of solitary nesting turtles to the
olive ridley turtle population. We studied the nesting ecology of solitary
nesting olive ridley turtles within the national park Parque Nacional Marino
Las Baulas (PNMB) in Playa Grande, Costa Rica (10°20′N, 85°51′W) and compared
these turtles to nearby arribada turtles. Between 2009/2010 and 2013/2014, an estimated
933 nesting activities occurred within PNMB. This number of turtles has not
changed significantly since 1995. During this study, 285 females were tagged;
of these, 30 females were encountered nesting on more than one occasion.
Significantly, more females emerged (31.1 % of tracks) during the third-quarter
moon, often a predictor. of arribada events, than any other moon phase.
However, there was no significant change in nesting activity at PNMB during
nearby arribada events. Mean hatching success (78.5 ± 23.4 % SD) was higher,
and incubation temperatures were lower (ranging from 28.3 to 33.4 °C) than at
nearby arribada beaches. Thus, clutches are relatively successful and may
produce males. These data suggest that solitary olive ridley turtles are
important. Currently, PNMB protects turtles from October to March; however,
hatching success was highest and 40 % of nesting activity occurred during the
rainy season (August–November). More turtles could be protected by increasing
the temporal scope of park protection.
Marine
Biology: DOI 10.1007/s00227-014-2583-7
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