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41.
42.
Redwood of the reef: growth and age of the giant barrel sponge Xestospongia muta in the Florida Keys 总被引:1,自引:0,他引:1
The growth of animals in most taxa has long been well described, but the phylum Porifera has remained a notable exception.
The giant barrel sponge Xestospongia muta dominates Caribbean coral reef communities, where it is an important spatial competitor, increases habitat complexity, and
filters seawater. It has been called the ‘redwood of the reef’ because of its size (often >1 m height and diameter) and presumed
long life, but very little is known about its demography. Since 1997, we have established and monitored 12 permanent 16 m
diameter circular transects on the reef slope off Key Largo, Florida, to study this important species. Over a 4.5-year interval,
we measured the volume of 104 tagged sponges using digital images to determine growth rates of X. muta. Five models were fit to the cubed root of initial and final volume estimates to determine which best described growth. Additional
measurements of 33 sponges were taken over 6-month intervals to examine the relationship between the spongocoel, or inner-osculum
space, and sponge size, and to examine short-term growth dynamics. Sponge volumes ranged from 24.05 to 80,281.67 cm3. Growth was variable, and specific growth rates decreased with increasing sponge size. The mean specific growth rate was
0.52 ± 0.65 year−1, but sponges grew as fast or slow as 404 or 2% year−1. Negative growth rates occurred over short temporal scales and growth varied seasonally, significantly faster during the
summer. No differences in specific growth rate were found between transects at three different depths (15, 20, 30 m) or at
two different reef sites. Spongocoel volume was positively allometric with increasing sponge size and scaling between the
vertical and horizontal dimensions of the sponge indicated that morphology changes from a frustum of a cone to cylindrical
as volume increases. Growth of X. muta was best described by the general von Bertalanffy and Tanaka growth curves. The largest sponge within our transects (1.23 × 0.98 m
height × diameter) was estimated to be 127 years old. Although age extrapolations for very large sponges are subject to more
error, the largest sponges on Caribbean reefs may be in excess of 2,300 years, placing X. muta among the longest-lived animals on earth. 相似文献
43.
Kirsten Halsnæs Amit Garg John Christensen Helene Ystanes Føyn Maryna Karavai Emilio La Rovere Matthew Bramley Xianli Zhu Catherine Mitchell Joyashree Roy Kanako Tanaka Hidefumi Katayama Carlos Mena Imoh Obioh Igor Bashmakov Stanford Mwakasonda Myong-Kyoon Lee Marlene Vinluan Yu Joe Huang Laura Segafredo 《Mitigation and Adaptation Strategies for Global Change》2014,19(1):45-71
The aim of this paper is to assess how policy goals in relation to the promotion of green growth, energy security, pollution control and greenhouse gas (GHG) emissions reductions have been aligned in policies that have been implemented in selected countries during the last decades as a basis for discussing how a multi objective policy paradigm can contribute to future climate change mitigation. The paper includes country case studies from Brazil, Canada, China, the European Union (EU), India, Japan, Mexico, Nigeria, South Africa, South Korea and the United States covering renewable energy options, industry, transportation, the residential sector and cross-sectoral policies. These countries and regions together contribute more than two thirds of global GHG emissions. The paper finds that policies that are nationally driven and that have multiple objectives, including climate-change mitigation, have been widely applied for decades in both developing countries and industrialised countries. Many of these policies have a long history, and adjustments have taken place based on experience and cost effectiveness concerns. Various energy and climate-change policy goals have worked together in these countries, and in practice a mix of policies reflecting specific priorities and contexts have been pursued. In this way, climate-change mitigation has been aligned with other policy objectives and integrated into broader policy packages, though in many cases specific attention has not been given to the achievement of large GHG emission reductions. Based on these experiences with policy implementation, the paper highlights a number of key coordination and design issues that are pertinent to the successful joint implementation of several energy and climate-change policy goals. 相似文献
44.
Hydrologic analysis for coastal wetland restoration 总被引:1,自引:0,他引:1
Increasing recognition of the value of tidal wetlands has led to interest in how to restore and enhance areas that have been modified by human activity. The policy of recognizing restoration or enhancement as mitigation for destruction of other wetlands is controversial. Once policy questions are separated from technical questions, the steps in a successful project are straightforward A key element in the design of a successful project is quantitative hydraulic and hydrologic analysis of alternatives. Restoration projects at two sites in California used a combination of empirical geomorphic relationships, numerical modeling, and verification with field observations. Experience with these and other wetland restoration projects indicates the importance of longterm postproject monitoring, inspection, and maintenance 相似文献
45.
The ability of surface flow and subsurface flow simulated wetlands to remove heavy metals from a NaCI-enriched wastewater was examined, employing bulrush (Scirpus validus) and cattail (Typha angustifolia) plants, and two organically amended substrates (mixtures of mushroom compost and leaf litter,with topsoil) with a limestone liner. A simulated wastewater solution containing Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn as chloride salts was added to the wetlands at a rate of 0.3 l h–1. During 12 weeks of surface flow, Fe was retained most efficiently (74%), and Mn the least (24%). Most metal retention occurred in residual forms, primarily in the upper 5 cm of the substrate. A subsequent 10 week subsurface flow treatment exhibited greater removal efficiencies for all metals, probably due to increased contact with the highly buffered lower substrate. During both treatments, bioaccumulation occurred in plants, but accounted for a very small portion of the total metal removal. Plant species did not significantly influence wetland performance with respect to metal retention. Substrate type did not affect removal efficiency for most metals, but did influence the forms of the metals retained in the wetland.To whom correspondence should be addressed. 相似文献
46.
Mitchell J. Small Bernard J. Cosby Ronald J. Marnicio Max Henrion 《Environmental monitoring and assessment》1995,35(2):113-136
The empirical direct distribution model for lake acidification is calibrated for use in an integrated assessment model which predicts the regional impact of an acid deposition control strategy. The calibration is based on the mechanistic Model of Acidification of Groundwater in Catchments (MAGIC). The models are applied jointly to a set of 33 statistically-selected lakes in the Adirondack region of New York. Calibration of the direct distribution model is based on a step-function application of acid deposition to MAGIC. Comparative evaluations of the resulting model predictions are made using historic deposition estimates and two alternative future deposition scenarios. The predictions of the direct distribution model match well the shapes and patterns of change of the regional distributions of ANC and pH predicted by MAGIC, the short- and medium-term dynamics of these changes, and the effect of including organic acids. However, small, long-term decreases in the fraction of incoming acid deposition neutralized by lakes and their watersheds predicted by MAGIC are not reproduced. 相似文献
47.
Non-structural adjustments in floodplain management are often avoided because they are seen to infringe on personal rights, adversely affect property values and restrict local tax bases. Land acquisition programs in urban areas encounter a further problem when they lead to demolition of buildings and other structures considered to have historical or architectural value. An experience in Cambridge, Ontario demonstrates that the potential conflict between flood damage reduction and historical preservation objectives can be exacerbated as a result of uncoordinated planning efforts, inflexibility in interpreting mandates, unclear roles for participating agencies, and lack of cooperation Many of these dilemmas can be resolved through consultation and discussion early in the planning process as well as through a willingness to be flexible and to search for a compromise 相似文献
48.
Carini F Atkinson CJ Collins C Coughtrey PJ Eged K Fulker M Green N Kinnersley R Linkov I Mitchell NG Mourlon C Ould-Dada Z Quinault JM Robles B Stewart A Sweeck L Venter A 《Journal of environmental radioactivity》2005,84(2):271-284
Although fruit is an important component of the diet, the extent to which it contributes to radiological exposure remains unclear, partially as a consequence of uncertainties in models and data used to assess transfer of radionuclides in the food chain. A Fruits Working Group operated as part of the IAEA BIOMASS (BIOsphere Modelling and ASSessment) programme from 1997 to 2000, with the aim of improving the robustness of the models that are used for radiological assessment. The Group completed a number of modelling and experimental activities including: (i) a review of experimental, field and modelling information on the transfer of radionuclides to fruit; (ii) discussion of recently completed or ongoing experimental studies; (iii) development of a database on the transfer of radionuclides to fruit; (iv) development of a conceptual model for fruit and (v) two model intercomparison studies and a model validation study. The Group achieved significant advances in understanding the processes involved in transfer of radionuclides to fruit. The work demonstrated that further experimental and modelling studies are required to ensure that the current generation of models can be applied to a wide range of scenarios. 相似文献
49.
50.
Erickson Mitchell D. 《Environmental science and pollution research international》2020,27(9):8926-8937
Environmental Science and Pollution Research - PCB forensic science is the process of identifying the source(s) of polychlorinated biphenyls (PCBs) at a site in the context of a legal proceeding to... 相似文献