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161.
Appraisal of visual assessments of habitat complexity and benthic composition on coral reefs 总被引:4,自引:0,他引:4
Visual assessments of topographic habitat structure and benthos on coral reefs were appraised using quantitative data collected
from 16 replicate surveys within each of 21 sites on Seychelles reefs. Results from visual assessments of reef benthos were
similar to those obtained using techniques frequently used to assess benthic complexity and composition. Visual estimates
of habitat topography were correlated with rugosity, reef height and holes of 10–70 cm diameter, whilst visual estimates of
benthic composition were very similar to those obtained from line intercept transects. Visual estimates of topography correlated
strongly with species richness of fish communities and explained 42% of the variation in these data. The relationship between
visual estimates of topography and species richness is strongest with fish 10–30 cm total length (TL), abundance of fish within
this size category also correlating positively with topographic visual assessments. Visual techniques are prone to observer
bias, however with regular training they can be used to quickly provide a reliable and effective means of assessing habitat
complexity and benthos on coral reefs. 相似文献
162.
John E. Elliott Megan L. Harris Laurie K. Wilson Philip E. Whitehead Ross J. Norstrom 《Ambio-人类环境杂志》2001,30(7):416-428
从1983~1998年,沿加拿大不列颠哥伦比亚海岸,我们监测了21处大蓝鹭(Ardea herodias)结巢处卵内多氯二苯并-p-二恶英 (PCDDs)、二苯并呋喃(PCDFs) 和多氯联苯 (PCBs)的污染情况。20世纪90年代早期,主要的同类物如1,2,3,7,8-PnCDD、 1,2,3,6,7,8-HxCDD、2,3,7,8-TCDD、2,3,7,8-TCDF、1,2,3,7,8,9-HxCDD 和2,3,4,7,8-PnCDF在纸浆厂分子氯漂白技术被新的漂白技术替代以及氯基酚类木材保存剂和抗木材变色剂的使用被严格地限制之后有显著下降。被捕食的鱼与大蓝鹭卵内污染物水平之间的强正线性回归说明,每天在本地摄食的食物是大蓝鹭暴露于污染物的一个重要路径。从1985年到1991年,在某些栖居地的大蓝鹭卵内所测到的毒当量浓度(TEQs)足以在小鹭体内产生胚胎毒性。尽管PCDD/Fs有所减少,但估计整个80年代有些城市中苍鹭栖居地的毒当量浓度由于多氯联苯的作用而居高不下。 相似文献
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Bethune Carmichael Greg Wilson Ivan Namarnyilk Sean Nadji Sally Brockwell Bob Webb Fred Hunter Deanne Bird 《Mitigation and Adaptation Strategies for Global Change》2018,23(2):231-255
Hundreds of thousands of significant archaeological and cultural heritage sites (cultural sites) along the coasts of every continent are threatened by sea level rise, and many will be destroyed. This wealth of artefacts and monuments testifies to human history, cosmology and identity. While cultural sites are especially important to local and Indigenous communities, a stall in coordinated global action means adaptation at a local scale is often unsupported. In response, this paper produces a practical climate change risk analysis methodology designed for independent, community-scale management of cultural sites. It builds on existing methods that prioritise sites most at risk from climate impacts, proposing a field survey that integrates an assessment of the relative cultural value of sites with assessment of exposure and sensitivity to climate impacts. The field survey also stands as a monitoring program and complements an assessment of organisational adaptive capacity. The preliminary field survey was tested by Indigenous land managers in remote northern Australia at midden and rock art sites threatened by sea level rise, extreme flood events and a range of non-climactic hazards. A participatory action research methodology—incorporating planning workshops, semi-structured interviews and participant observations—gave rise to significant modifications to the preliminary field survey as well as management prioritisation of 120 sites. The field survey is anticipated to have global application, particularly among marginalised and remote Indigenous communities. Well-planned and informed participation, with community control, monitoring and well-informed actions, will contribute significantly to coordinated global and regional adaptation strategies. 相似文献
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166.
Alastair J Wilson Andrew Grimmer Gil G. Rosenthal 《Behavioral ecology and sociobiology》2013,67(7):1151-1161
Although our understanding of how animal personality affects fitness is incomplete, one general hypothesis is that personality traits (e.g. boldness and aggressiveness) contribute to competitive ability. If so, then under resource limitation, personality differences will generate variation in life history traits crucial to fitness, like growth. Here, we test this idea using data from same-sex dyadic interaction trials of sheepshead swordtails (Xiphophorus birchmanni). In males, there was evidence of repeatable variation across a suite of agonistic contest behaviours, while repeatable opponent effects on focal behaviour were also detected. A single vector explains 80 % of the among-individual variance in multivariate phenotype and can be viewed as aggressiveness. We also find that aggressiveness predicts dominance—the repeatable tendency to win food in competition—and dominant individuals show faster post-trial weight gain (independently of initial size). In females, a dominance hierarchy predictive of weight gain was also found, but there was no evidence of variation in aggressiveness. While size often predicts contest outcome, our results show that individuals may sometimes grow larger because they are behaviourally dominant rather than vice versa. When resources are limited, personality traits such as aggression can influence growth, life history, and fitness through impacts on resource acquisition. 相似文献
167.
Male seahorses (genus Hippocampus) provide all post-fertilization parental care, yet despite high levels of paternal investment, these species have long been
thought to have conventional sex roles, with female mate choice and male–male competition. Recent studies of the pot-bellied
seahorse (Hippocampus abdominalis) have shown that sex-role reversal occurs in high-density female-biased populations, indicating that male mating preferences
may lead to sexual selection on females in this species. Egg size, egg number, and offspring size all correlate positively
with female body size in Hippocampus, and by choosing large mating partners, male seahorses may increase their reproductive success. While male brood size is
also positively correlated with body size, small H. abdominalis males can carry exceptionally large broods, suggesting that the fecundity benefits of female preference for large partners
may be limited. We investigated the importance of body size in reproductive decisions of H. abdominalis, presenting focal individuals of both sexes with potential mating partners of different sizes. Mating preferences were quantified
in terms of time spent courting each potential partner. Male seahorses were highly active throughout the mate-choice trials
and showed a clear behavioral preference for large partners, while females showed significantly lower levels of activity and
equivocal mating preferences. The strong male preferences for large females demonstrated here suggest that sexual selection
may act strongly on female body size in wild populations of H. abdominalis, consistent with predictions on the importance of female body size for reproductive output in this species.
An erratum to this article can be found at 相似文献
168.
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170.
Richard A. Brown James G. Mueller Alan G. Seech James K. Henderson John T. Wilson 《补救:环境净化治理成本、技术与工艺杂志》2009,20(1):9-20
While biologically mediated reductive dechlorination continues to be a significant focus of chlorinated solvent remediation, there has been an increased interest in abiotic reductive processes for the remediation of chlorinated solvents. In situ chemical reduction (ISCR) uses zero‐valent iron (ZVI)–based technologies, such as nanoscale iron and bimetallic ZVI, as well as naturally occurring reduced minerals incorporating dual‐valent iron (DVI), such as magnetite, green rust, and iron sulfides that are capable of dechlorinating solvents. A more recent area of development in ISCR has been in combining biological and abiotic processes. There are several ways in which biological and abiotic processes can be combined. First, the interaction between the two may be “causative.” For example, the Air Force Center for Engineering and the Environment's biogeochemical reductive dechlorination (BiRD) technology combines a mulch barrier with hematite and gypsum to create an iron‐sulfide‐based reducing zone. Biodegradation under sulfate‐reducing conditions produces sulfide that combines with the hematite to form iron sulfides. As such, the BiRD technology is “causative”; the biological processes create reducing minerals. The biological generation of other reducing minerals such as magnetite, siderite, and green rust is feasible and is, with magnetite, observed in nature at some petroleum sites. A second type of interaction between abiotic and biotic processes is “synergistic.” For example, biological processes can enhance the activity of reduced metals/minerals. This is the basis of the EHC® ISCR technologies, which combine ZVI with a (slowly) degradable carbon substrate. This combination rapidly creates buffered, strongly reducing conditions, which result in more complete solvent degradation (i.e., direct mineralization). The extent and level of reducing activity commonly observed are much greater when both the carbon substrate and the ZVI are present. When the carbon substrate is expended, the reducing activity due to ZVI alone is much less. The understanding of biogeochemical processes and their impact on abiotic processes is still developing. As that understanding develops, new and improved methods will be created to enhance volatile organic compound destruction. © 2009 Wiley Periodicals, Inc. 相似文献