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51.
There are two approaches in the application of satellite sensors to marine pollution studies. Satellite sensors are used to observe and characterize ocean pollutants such as industrial wastes and oil. in addition, satellite observations provide information useful in illuminating processes such as eutrophi-cation or air-sea exchange of CO2, that are important in determining the distribution and fate of pollutants. Satellite technology is an important tool in monitoring and studying ocean pollution. Visible sensors have been used to observe and characterize sewage sludge and industrial wastes dumped at sea. Oil slicks have been observed with Landsat, AVHRR and SAR imagery. Besides directly detecting pollutants, satellite sensors are useful for analyzing ocean processes that are influential in the fate of pollutants. These processes include eutrophication of coastal waters and the distribution of suspended matter. the fate of excess CO2 can be addressed using scatterometer-derived estimates of wind speeds to determine the CO2 exchange coefficient at the sea surface on a global scale. 相似文献
52.
Ocean acidification, as a result of increased atmospheric CO2, is predicted to lower the pH of seawater to between pH 7.6 and 7.8 over the next 100 years. The greatest changes are expected
in polar waters. Our research aimed to examine how echinoid larvae are affected by lower pH, and if effects are more pronounced
in polar species. We examined the effects of lowered pH on larvae from tropical (Tripneustes gratilla), temperate (Pseudechinus huttoni, Evechinus chloroticus), and a polar species (Sterechinus neumayeri) in a series of laboratory experiments. Larvae were reared in a range of lower pH seawater (pH 6.0, 6.5, 7.0, 7.5, 7.7, 7.8
and ambient), adjusted by bubbling CO2 gas. The effect of pH on somatic and skeletal growth, calcification index, development and survival were quantified, while
SEM examination of the larval skeleton provided information on the effects of seawater pH on the fine-scale skeletal morphology.
Lowering pH resulted in a decrease in survival in all species, but only below pH 7.0. The size of larvae were reduced at lowered
pH, but the external morphology (shape) was unaffected. Calcification of the larval skeleton was significantly reduced (13.8–36.9%
lower) under lowered pH, with the exception of the Antarctic species, which showed no significant difference. SEM examination
revealed a degradation of the larval skeletons of Pseudechinus and Evechinus when grown in reduced pH. Sterechinus and Tripneustes showed no apparent difference in the skeletal fine structure under lowered pH. The study confirms the need to look beyond
mortality as a single endpoint when considering the effects of ocean acidification that may occur through the 21st century,
and instead, look for a suite of more subtle changes, which may indirectly affect the functioning of larval stages. 相似文献
53.
Chaochung Tsai Sylvia Yang Alan C. Trimble Jennifer L. Ruesink 《Marine Biology》2010,157(9):1929-1936
Dwarf eelgrass (duckgrass; Zostera japonica) and Manila clams (Ruditapes philippinarum) are two introduced species that co-occur on intertidal flats of the northeast Pacific. Through factorial manipulation of
clam (0, 62.5, 125 clams m−2) and eelgrass density (present, removed by hand, harrowed), we examined intra- and interspecific effects on performance,
as well as modification of the physical environment. The presence of eelgrass reduced water flow by up to 40% and was also
observed to retain water at low tide, which may ameliorate desiccation and explain why eelgrass grew faster in the presence
of conspecifics (positive feedback). Although shell growth of small (20–50 mm) clams was not consistently affected by either
treatment in this 2-month experiment, clam condition improved when eelgrass was removed. Reciprocally, clams at aquaculture
densities had no effect on eelgrass growth, clam growth and condition, or porewater nutrients. Overall, only Z. japonica demonstrated strong population-level interactions. Interspecific results support an emerging paradigm that invasive marine
ecosystem engineers often negatively affect infauna. Positive feedbacks for Z. japonica may characterize its intraspecific effects particularly at the stressful intertidal elevation of this study (+1 m above mean
lower low water). 相似文献
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Bleaching (visible loss of symbiont color) in populations of the diatom-bearing foraminifer Amphistegina has been recorded from reefs worldwide since 1991. Field studies and previous laboratory experiments have strongly implicated solar radiation as a factor in bleaching stress. The influence of spectral quality and quantity of photosynthetically active radiation (PAR) and ultraviolet radiation (UV) on growth rates and bleaching in Amphistegina gibbosa was investigated in the laboratory using fluorescent sources of PAR (blue with a spectral peak at 450 nm and white with a 600-nm spectral peak) and biologically effective ultraviolet radiation [UVB (280–320 nm)]. Growth rate, as indicated by increase in maximum shell diameter, saturated at a PAR of 6–8 mol photon m–2 s–1, increased in blue light, and was not influenced by UVB0.0162 W m–2. Frequency of bleaching increased with increasing PAR photon flux density and with exposure to shorter wavelengths, with or without an increase in total energy. Growth was significantly inhibited by UVB at 0.105 W m–2. Specimens in treatments exposed to UVB to PAR ratios >0.003 became dark in color, rather than bleaching, which previous cytological studies indicate is a photo-protective response. Implications of these experiments are that environmental factors that affect either the spectral quality or quantity of solar radiation can influence bleaching in Amphistegina.Communicated by P.W. Sammarco, Chauvin
相似文献
Dana E. WilliamsEmail: Phone: +1-305- 3614569Fax: +1-305-3614499 |
59.
Animals that guide directions of their locomotion or their migration routes by the lines of the geomagnetic field use either polarity or inclination compasses to determine the field polarity (the north or south direction). Distinguishing the two compass types is a guideline for estimation of the molecular principle of reception and has been achieved for a number of animal groups, with the exception of insects. A standard diagnostic method to distinguish a compass type is based on reversing the vertical component of the geomagnetic field, which leads to the opposite reactions of animals with two different compass types. In the present study, adults of the mealworm beetle Tenebrio molitor were tested by means of a two-step laboratory test of magnetoreception. Beetles that were initially trained to memorize the magnetic position of the light source preferred, during the subsequent test, this same direction, pursuant geomagnetic cues only. In the following step, the vertical component was reversed between the training and the test. The beetles significantly turned their preferred direction by 180 degrees. Our results brought until then unknown original findings that insects, represented here by the T. molitor species, use-in contrast to another previously researched Arthropod, spiny lobster-the inclination compass. 相似文献
60.
Ivana Jankovská Daniela Miholová Iva Langrová Vladimír Bejček Jaroslav Vadlejch Dana Kolihová Miloslav Šulc 《Environmental pollution (Barking, Essex : 1987)》2009,157(8-9):2584-2586
Bioaccumulation of cadmium, chromium, copper, manganese, nickel, lead and zinc in small terrestrial rodents – voles and their cestode parasite Paranoplocephala dentata was studied. Contents of Pb, Mn, Ni and Zn in the parasite were found to be higher than in the kidney and liver of the parasitized animals. Lead level in the cestode was 37 fold higher than in the liver of the infected rodents. Bioaccumulation factors of zinc, nickel and manganese in the cestode are mostly in the range from 2 to 4.5. Considering the different contents of manganese and zinc in livers of non-parasitized and parasitized rodents, kidney tissue was found to be more reliable than liver as an indicator of environmental pollution by manganese and zinc; the kidneys of parasitized animals showed no significant change in the concentrations of those elements that are accumulated in the cestode. 相似文献