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Coral cover and partial mortality on anthropogenically impacted coral reefs at Eilat, northern Red Sea 总被引:1,自引:0,他引:1
A photographic analysis was conducted at five shallow reef sites (5-6 m) at Eilat (northern Red Sea) to study changes in live coral cover during a 2-year period. Logit regression analysis showed that levels of total oxidized nitrogen (TON; NO(2)+NO(3)) and the presence of SCUBA divers were significant explicative variables of coral partial mortality, while sedimentation rate was not significant. Sites exposed to mean TON levels above 0.4 microM TON showed significantly lower live stony coral cover and abundance per m(2), and higher partial mortality of coral colonies than sites exposed to lower TON. These findings may be useful in establishing limits for TON levels at Eilat, but must be interpreted with caution due to the complexity of nutrient dynamics in coral reefs, the uncertainty of the effects of nutrients on coral physiological processes, and the possibility of interactions among multiple coral stressors. 相似文献
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Praveen K. Thakur Sreyasi Maiti Nanette C. Kingma V. Hari Prasad S. P. Aggarwal Ashutosh Bhardwaj 《Natural Hazards》2012,61(2):501-520
Vulnerability assessment of natural disasters is a crucial input for risk assessment and management. In the light of increasing
frequency of disasters, societies must become more disaster resilient. This research tries to contribute to this aim. For
risk assessment, insight is needed into the hazard, the elements at risk and their vulnerabilities. This study focused on
the estimation of structural vulnerability due to flood for a number of structural elements at risk in the rural area of Orissa,
India (Kendrapara), using a community-based approach together with geospatial analysis tools. Sixty-three households were
interviewed about the 2003 floods in 11 villages and 166 elements at risk (buildings) were identified. Two main structural
types were identified in the study area, and their vulnerability curves were made by plotting the relationships between flood
depth and vulnerability for each structural type. The vulnerability ranges from 0 (no damage) to 1 (collapse/total damage).
Structural type-1 is characterized by mud wall/floor material and a roof of paddy straw, and structural type-2 is characterized
by reinforced cement concrete (RCC) walls/floor and a RCC roof. The results indicate that structural type-1 is most vulnerable
for flooding. Besides flood depth, flood duration is also of major importance. Houses from structural type-1 were totally
collapsed after 3 days of inundation. Damage of the houses of structural type-2 began after 10 days of inundation. 相似文献
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