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101.
Water flow and prey capture by three scleractinian corals, Madracis mirabilis, Montastrea cavernosa and Porites porites, in a field enclosure 总被引:8,自引:0,他引:8
Scleractinian corals experience a wide range of flow regimes which, coupled with colony morphology, can affect the ability
of corals to capture zooplankton and other particulate materials. We used a field enclosure oriented parallel to prevailing
oscillatory flow on the forereef at Discovery Bay, Jamaica, to investigate rates of zooplankton capture by corals of varying
morphology and polyp size under realistic flow speeds. Experiments were carried out from 1989 to 1992. Particles (Artemia salina cysts) and naturally occurring zooplankton attracted into the enclosures were used as prey for the corals Madracis mirabilis (Duchassaing and Michelotti) (narrow branches, small polyps), Montastrea cavernosa (Linnaeus) (mounding, large polyps), and Porites porites (Pallas) (wide branches, small polyps). This design allowed corals to be used without removing them or their prey from the
reef environment, and avoided contact of zooplankton with net surfaces. Flow speed had significant effects on capture rate
for cysts (M. mirabilis), total zooplankton (M. mirabilis, M. cavernosa), and non-copepod zooplankton (M. mirabilis). Zooplankton prey capture increased with prey concentration for M. mirabilis and M. cavernosa, over a broad range of concentrations, indicating that saturation of the feeding response had not occurred until prey density
was over 104 items m−3, a concentration at least an order of magnitude greater than the normal range of reef zooplankton concentrations. Location
of cyst capture on coral surfaces was not uniform; for M. cavernosa, sides and tops of mounds captured most particles, and for P. porites, capture was greatest near branch tops, but was close to uniform for M. mirabilis branches in all flow conditions. The present study confirms laboratory flume results, and field results for other species,
suggesting that many coral species experience particle flux and encounter rate limitations at low flow speeds, decreasing
potential zooplankton capture rates.
Received: 17 September 1996 / Accepted: 22 November 1997 相似文献
102.
103.
Rashama Charles Ijoma Grace N. Matambo Tonderayi S. 《Journal of Material Cycles and Waste Management》2021,23(1):409-415
Journal of Material Cycles and Waste Management - Biomethane potentials (BMPs) for avocado oil processing by-products were determined using six different theoretical BMP prediction models and... 相似文献
104.
Mercury in sediment and fish from North Mississippi Lakes 总被引:7,自引:0,他引:7
Sediments and/or fish were collected from Sardis, Enid and Grenada Lakes, which are located in three different watersheds in North Mississippi, in order to assess mercury contamination. The mean total mercury concentration in sediments from Enid Lake in 1997 was 0.154 mg Hg/kg, while 1998 sediment concentrations in Sardis, Enid and Grenada Lakes were 0.112, 0.088 and 0.133 mg Hg/kg, respectively. Sediment mercury concentrations in 1999 were similar in all three lakes but, generally lower than 1998. Mean total mercury concentrations in edible fillets of fish collected from Enid Lake in 1998 were above the human health FDA action level (>1.0 mg Hg/kg) for bass (1.40), crappie (1.69) and gar (1.89); however, tissue concentrations were less than 1.0 mg Hg/kg in carp (0.63) and catfish (0.82). Human hazard indexes for each species was 1 for both adults and children, indicating that there is a potential for toxic effects to occur. In addition, calculated consumption limits indicate that adults may consume 4–12 oz. of fish per month, depending on the species consumed. For children, 2 oz. per month may be consumed. Further studies are needed to determine the exact environmental consequences and human health impacts associated with mercury contamination in North Mississippi and the Southeastern United States. 相似文献
105.
A modified time series approach, a Box-Jenkins regression with time series errors (RTSE) model plus a principal component (PC) trigger, has been developed to forecast peak daily 1-hr ozone (O3) in real time at the University of Wisconsin-Milwaukee North (UWM-N) during 1999 and 2002. The PC trigger acts as a predictor variable in the RTSE model. It tries to answer the question: will the next day be a possible high O3 day? To answer this question, three PC trigger rules were developed: (1) Hi-Low Checklist, (2) Discriminant Function Approach I, and (3) Discriminant Function Approach II. Also, a pure RTSE model without including the PC trigger and a persistence approach were tested for comparison. The RTSE model with DFA I successfully forecast the only two 1-hr federal exceedances (124 ppb), one in 1999 and one in 2002. In terms of the O3 100-ppb exceedances, 60-80% of the incorrect forecasts occurred with incorrect PC decisions. A few others may have been caused by unexpected O3-weather relations. When the three approaches used UWM-N data to forecast a 100-ppb exceedance somewhere in the Milwaukee, WI, metropolitan area, their performance was dramatically improved: the false alarm rate was reduced from 0.89 to 0.44, and the probability of detection was increased from 0.71 to 0.88. 相似文献
106.
Samson Gwali John Bosco Lamoris Okullo Gerald Eilu Grace Nakabonge Philip Nyeko Peter Vuzi 《Environment, Development and Sustainability》2012,14(3):347-363
Traditional practices are universally recognised as a basis for conservation of biodiversity. However, such practices are
often not included in natural resource conservation policies. This study assessed local conservation practices of shea trees
(Vitellaria paradoxa) within different farming systems in Uganda and developed conservation guidelines for the species. The assessment involved
300 respondents, 15 focus groups and 41 key informants. Content analysis was used to identify the most important management
and conservation practices. Local uses were categorised on the basis of shea tree products while differences in conservation
practices were analysed using the Friedman test. The results show that eight shea tree products are used for 36 different
purposes. Respondents’ age significantly influenced their knowledge about the shea tree. Traditional conservation practices
include on-farm retention during cultivation and the use of folklore (mainly taboos), customs and rituals. Traditional management
practices include weeding, bush burning, pollarding and pruning. Based on the current management and traditional conservation
practices, a framework for the conservation of shea trees is proposed for integration into conservation policy decisions. 相似文献
107.
Concentration gradient patterns of aerosol particles near interstate highways in the Greater Cincinnati airshed 总被引:1,自引:0,他引:1
Reponen T Grinshpun SA Trakumas S Martuzevicius D Wang ZM LeMasters G Lockey JE Biswas P 《Journal of environmental monitoring : JEM》2003,5(4):557-562
The objective of this study was to determine if there is an exposure gradient in particulate matter concentrations for people living near interstate highways, and to determine how far from the highway the gradient extends. Air samples were collected in a residential area of Greater Cincinnati in the vicinity of two major highways. The measurements were conducted at different distances from the highways by using ultrafine particle counters (measurement range: 0.02-1 microm), optical particle counters (0.3-20 microm), and PM2.5 Harvard Impactors (0.02-2.5 microm). The collected PM2.5 samples were analyzed for mass concentration, for elemental and organic carbon, and for elemental concentrations. The results show that the aerosol concentration gradient was most clearly seen in the particle number concentration measured by the ultrafine particle counters. The concentration of ultrafine particles decreased to half between the sampling points located at 50 m and 150 m downwind from the highway. Additionally, elemental analysis revealed a gradient in sulfur concentrations up to 400 m from the highway in a residential area that does not have major nearby industrial sources. This gradient was qualitatively attributed to the sulfate particle emissions from diesel engine exhausts, and was supported by the concentration data on several key elements indicative of traffic sources (road dust and diesel exhaust). As different particulate components gave different profiles of the diesel exposure gradient, these results indicate that no single element or component of diesel exhaust can be used as a surrogate for diesel exposure, but more comprehensive signature analysis is needed. This characterization is crucial especially when the exposure data are to be used in epidemiological studies. 相似文献
108.
109.
Male ornamentation is assumed to have evolved primarily from selection by female mate choice. Yet this is only one possible
reason for ornament evolution. Ornaments might also be useful in aggressive competition by improving opponent assessment between
males, or they might function to enhance signal detection by making males more conspicuous in the environment. We tested both
these ideas in territorial Anolis lizards in which female choice is either absent or secondary to males competing for territories that overlap female home
ranges. Male tail crests only evolved in species in which territory neighbors were distant, consistent with the signal detection
hypothesis. Once the tail crest had evolved, however, it seems to have become a signal in itself, with variation in the frequency
and size of tail crests within species correlating with variables predicted by the aggressive competition hypothesis. Our
study presents an apparent example of a male ornament in which the selection pressure leading to variation among species in
ornament expression is different from the selection pressure acting on variation within species. The Anolis tail crest is therefore likely to be an exaptation. We caution that conclusions made on the evolution of male ornaments are
dependent on the phylogenetic perspective adopted by a study. Studies restricted to single species are useful for identifying
selection pressures in contemporary settings (i.e., the current utility of traits), but may lead to erroneous conclusions
on the factors that initially lead to the origin of traits. 相似文献
110.
Thirteen sediment samples from different locations in the Niger Delta region of Nigeria were analyzed for the presence of 16 polynuclear aromatic hydrocarbons (PAHs) via gas chromatography/mass spectrometry. The specific target compounds for this study included naphthalene, acenaphthylene, acenaphthene, flourene, phenanthrene, anthracene, flouranthene, pyrene, benz[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]flouranthene, benzo[a]pyrene, benzo[ghi]perylene, dibenz[a,h]anthracene, and indeno[1,2,3-cd]pyrene. Four isotopically labeled polynuclear aromatic hydrocarbons (acanaphthene-d10, phenanthrene-d10, chrysene-d12 and perylene-d12) were used for internal standardization. All 16 PAHs were found in most of the thirteen samples with concentration ranging from 0.1 microg/kg to 28 microg/kg. It was also found that the 5 and 6-ring PAHs were present in higher concentrations than all the other compounds, indicating their high resistance to microbial degradation. 相似文献