Do Embedded Roadway Lights Protect Sea Turtles?

Street lighting on coastal roadways is often visible at sea turtle nesting beaches, and disrupts the nocturnal orientation of hatchlings as they crawl toward the sea. Our objective was to determine whether an alternative lighting system (light-emitting diodes, embedded in the roadway pavement) prevented orientation disruption. Hatchlings at the beach oriented normally when only the embedded lights were on, or when all lighting was switched off. However, turtles showed poor orientation when street lighting was on. Measurements confirmed that street lighting was scattered to the beach, whereas embedded lighting was not. We conclude that embedded lighting keeps the beach dark and thus protects sea turtles. However, on two overcast evenings, lighting (“skyglow”) from nearby development, reflected by cloud cover to the beach, weakened hatchling orientation. Thus, both indirect (reflected) and direct sources of lighting negatively impact the turtles.     

Are behavioural trade-offs all they seem? Counter-intuitive resolution of the conflict between two behaviours

The understanding of trade-offs between behaviours is fundamental to the study of animal behaviour. Individuals may often be faced with the choice of which of two mutually incompatible behaviours to perform. Here, I present a model investigating the trade-off between two behaviours, where one of the behaviours is crucial to the success of the other. I illustrate the results with examples, considering particularly a trade-off between territorial defence and courtship. I investigate how the ability of an individual to perform the behaviours changes the time or energy allocated to each behaviour. Intuition suggests that the time invested in performing a behaviour should decline as the individuals ability to perform the behaviour increases. Explicit, quantitative modelling suggests that this is not always the case. Instead, we see a pattern where investment in one of the behaviours at first increases and then decreases as the ability to perform the behaviour increases. This finding has implications for the empirical study of trade-offs between behaviours, since it could appear that individual ability has no effect on the trade-off under consideration. I discuss potential methods for distinguishing whether time allocation changes in a counter-intuitive, non-monotonic way with increasing individual ability, or whether there is indeed no effect.Communicated by C. St. Mary     

Play behavior and motor development in juvenile Belding’s ground squirrels (<Emphasis Type="Italic">Spermophilus beldingi</Emphasis>)

We evaluated the relationship between play behavior and motor development in juvenile Beldings ground squirrels (Spermophilus beldingi). We observed the social play behavior of juvenile S. beldingi during their primary play period and conducted motor skills tests at the beginning and end of the play period. We also placed different-sized boxes in juveniles natal areas during the play period and observed box climbing behavior to assess the difficulty of non-social play tasks undertaken by juveniles. Rates of social play were greater in heavy compared to light individuals, supporting the idea that juveniles must selectively allocate available energy among competing demands such as growth and play behavior. Juveniles played almost exclusively with littermates; however, they did not play at equal rates with all partners. Rather, they tended to have one preferred partner and to devote significantly less time to playing with each additional partner, indicating that stability and familiarity are important in social play interactions. Motor skill levels at the end of the play period were greater among juveniles who played with many compared to few partners, suggesting that exposure to a variety of play interactions helps facilitate motor development. Improvement in motor skills was greater among juveniles who played at high compared to low rates, had several compared to few male play partners, and engaged in several compared to few play bouts with male partners, suggesting that elements of play with male partners prominently influence motor development. The partner with whom males played at the highest rate tended to be male, and rates of social play were highest in male biased litters, raising the possibility that improvement in motor proficiency arising from play with males may be especially important for young males. The size of experimental boxes that juveniles climbed increased during the play period, supporting the idea that individuals choose play tasks that pose the greatest challenge.Communicated by T. Czeschlik     

Growth of Phragmites australis (Cav.) Trin ex. Steudel in mine water treatment wetlands: effects of metal and nutrient uptake

The abandoned mine of Shilbottle Colliery, Northumberland, UK is an example of acidic spoil heap discharge that contains elevated levels of many metals. Aerobic wetlands planted with the common reed, Phragmites australis, were constructed at the site to treat surface runoff from the spoil heap. The presence of a perched water table within the spoil heap resulted in the lower wetlands receiving acidic metal contaminated water from within the spoil heap while the upper wetland receives alkaline, uncontaminated surface runoff from the revegetated spoil. This unique situation enabled the comparison of metal uptake and growth of plants used in treatment schemes in two cognate wetlands. Results indicated a significant difference in plant growth between the two wetlands in terms of shoot height and seed production. Analyses of metal and nutrient concentrations within plant tissues provided the basis for three hypotheses to explain these differences: (i) the toxic effects of high levels of metals in shoot tissues, (ii) the inhibition of Ca (an essential nutrient) uptake by the presence of metals and H+ ions, and (iii) low concentrations of bioavailable nitrogen sources resulting in nitrogen deficiency. This has important implications for the engineering of constructed wetlands in terms of the potential success of plant establishment and vegetation development.     

TOWARDS CHARACTERIZING AND PLANNING FOR DROUGHT IN VERMONT‐PART I: A CLIMATOLOGICAL PERSPECTWE1

ABSTRACT: In the Green Mountain state of Vermont, droughts of one form or another and of varying intensities, seventies, and areal extent are not uncommon occurrences. The 1990s were marked by at least three drought events of which the 1998 to 1999 was the most recent. In spite of this recurrence, ongoing drought monitoring and mitigative planning efforts are not as advanced as they could be and no official drought plan exists for the state. This article is the first of two in this volume. It summarizes the cascade of drought types that impacted the state during the 1998 to 1999 episode. From a number of precipitation statistics and drought indices, fine spatial scales (county or better) were found to best capture the character of drought impacts, while the weekly time step is recommended as the temporal unit around which to base planning and monitoring efforts. The companion article outlines a possible framework for drought planning efforts and highlights key constituencies to be included in the process.     

Stoichiometry, growth, and fecundity responses to nutrient enrichment by invertebrate grazers in sub-tropical turtle grass (Thalassia testudinum) meadows

Although the effectiveness of herbivores in mitigating the effects of nutrient enrichment is well documented, few studies have examined the effects of nutrient enrichment on components of consumer fitness. Enclosures were deployed in shallow turtle grass (Thalassia testudinum) beds in Florida Bay, Florida in fall 2003, spring 2004, and fall 2004 to measure the effects of nitrogen and phosphorous enrichment on the growth, fecundity, and stoichiometry of three invertebrate epiphyte grazers commonly associated with T. testudinum. The gastropod Turbo castanea exhibited significantly greater wet weight gain and lower C:P and N:P in enriched than in ambient treatments. Although nutrient enrichment did not have any significant effects on the growth of caridean shrimp (treatment consisted of several different caridean shrimp species), their C:N was significantly lower in enriched treatments. The final size and stoichiometry of the hermit crab Paguristes tortugae was not significantly affected by nutrient enrichment, nor did nutrient enrichment significantly affect the fecundity of P. tortugae, the only grazer in which gravid individuals or egg masses were present. Our study demonstrated that nutrient enrichment of primary producers can positively affect the growth of marine invertebrate grazers and alter their stoichiometry; however, these effects were species-specific and may be dependent upon the life stage, specific diets, and/or compensatory feeding habits of the grazers.     

Synthesis of chromium-containing pigments from chromium recovered from leather waste

Cobalt-chromite green and chrome-tin pink pigments have been prepared from chromium extracted from leather shavings produced as a waste product of the leather-tanning industry. The alkaline agent (NaOH, CaO, MgO, NH4OH) used in the extraction process influences the nature of the final product. The effect of the NH4OH:CaO ratio on the final product in the case of cobalt-chromite green was examined. The pigments obtained were characterized by FT-IR and X-ray diffraction (XRD). Colour measurements were compared with those recorded from materials prepared from pure Cr2O3. The leaching of Cr(VI) from the materials was examined by UV spectroscopy.