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51.
Bianca A. Hernández Zachary A. Mitchell Clinton R. Robertson Astrid N. Schwalb 《水产资源保护:海洋与淡水生态系统》2021,31(4):903-915
- Conservation efforts have increased in response to global mussel declines, and effective surveys are a crucial step in assessing and monitoring mussel populations and in determining their conservation status. The burrowing behaviour of mussels can affect their detectability, and a better understanding of these behaviours would help to improve survey design and guidelines.
- The burrowing depth of mussels may differ between seasons, habitat conditions, species, and individuals, and little is known about the burrowing behaviour of mussels in subtropical rivers.
- Burrowing depth variation was examined and compared at three sites in the San Marcos, Guadalupe, and San Antonio river drainages in central Texas. In addition, laboratory experiments were used to determine whether observed differences between field sites and seasons could be linked to differences in substrate type and water temperature and to examine differences between species.
- Seasonal variation in burrowing depth was found at all field sites, and water temperature was a significant factor for explaining variation in burrowing depth, but there was no clear relationship between burrowing depth and temperature in shorter term laboratory experiments, where individual variation was high and burrowing behaviour seemed to be solely a function of time.
- Mussels burrowed significantly deeper in finer substrate (sand vs. gravel) in both field and laboratory experiments. Few significant differences between species were found in the field, but no differences were found in the laboratory experiments.
- The results suggest that surveys may need to follow different guidelines depending on local conditions, such as substrate and water temperature. Surveys will be less efficient and may fail to detect larger proportions of populations in colder water temperatures. In addition, a larger proportion of burrowed mussels can be expected at sites with finer substrate, such as sand. Under these conditions, visual searches will not suffice, as a large part of the population or specific species may be overlooked.
52.
Ning WANG Fengxin WANG Clinton C. SHOCK Lei GAO Chaobiao MENG Zejun HUANG Jianyu ZHAO 《农业科学与工程前沿(英文版)》2022,9(4):614
53.
Expansion of the global terrestrial protected area system 总被引:2,自引:0,他引:2
Under the Convention on Biological Diversity, the world’s governments set a goal of protecting 10% of all ecological regions by 2010. We evaluated progress toward that goal for the world’s major terrestrial biomes, realms, and ecoregions. Total land area under any legal protection has increased from previous estimates to 12.9%, a notable achievement, although only 5.8% has strict protection for biodiversity. For biomes, protection ranges from 4% to 25%, with six of 14 biomes still below the 10% level. Geographic patterns of protection have a distinct bias, with higher rates of protection in New World realms than Old World realms. Of the world’s terrestrial ecoregions, half do not meet the 2010 Target and 76% have less than 10% of their area strictly protected. Approximately 13% of ecoregions have no strict protected areas. Recent years have seen an expansion of the protected area network, with an average of 0.13% of the global land area added per year. Most of the expansion since 2003 though has been in Brazil, particularly the Amazon. Without major investments in conservation, spread across the world’s ecosystems, the world will likely miss the 2010 target. 相似文献
54.
Rhizophora mangle L. dominated 10 overwash islands within Tampa Bay forming the northernmost mangrove forests on the west coast of Florida. The mean number of trees and basal area were 5040 trees ha-1 and 20.5m2ha-1, respectively. Basal areas ranged from 1.1 (Avicennia germinans (L.) Stern), to 2.6m2ha-1 (Laguncularia racemosa Gaertner), to 16.8 (R. mangle). Cockroach Bay mangroves are small (5.8–7.0m tall) versus coastal forests of south Florida and the Caribbean. Total litter production for a 12 month period was maximal in September for fringing (7.4gdwtm-2d-1) and interior (8.7gdwtm-2d-1) areas with the two zones not being significantly different. Average litter fall (3.1gdwtm-2d-1) was similar to more tropical Caribbean mangals. Leaves accounted for 68 of the litter and reproductive material for 6, being similar to tropical riverine and overwash marine angiosperm communities on the Mexican coast. Although mangrove forests in Tampa Bay are small in stature and experience cold damage and occasional frosts, their litter fall is similar in biomass to that of more tropical mangals. However, their reproductive output is low based on litter fall versus more tropical mangals suggesting that the northern extension is less than optimum. Macroalgal diversity was low (10 species) as compared to Caribbean mangals. Macroalgal turf (0.8gCm-2d-1) and epiphyte communities of A.germinans pneumatophores (2.7gCm-2d-1) have productivity levels that are equal to or greater than those of Caribbean mangals. 相似文献
55.
56.
Michael S. Watt Murray R. Davis Peter W. Clinton Graham Coker Craig Ross John Dando Roger L. Parfitt Robyn Simcock 《Forest Ecology and Management》2008,256(1-2):180-190
New Zealand is committed to developing sustainable forest management practices as evidenced through Government involvement in international forestry agreements such as the Montreal Process, and the forestry sector's adoption of forest certification mechanisms. Despite this, there is little quantitative evidence of how plantation forestry affects site quality and long-term site productivity. To address this issue, a nationwide study of site quality was established at 31 key sites covering the range of edaphic and environmental conditions for New Zealand plantation forests. At each location, eight short-term site quality plots were planted at a very high stand density (40,000 stems ha−1) to rapidly identify key soil indicators of growth which may be useful for determining site sustainability. The plots at each site were arranged in a factorial design with the following three factors: species (Pinus radiata D. Don and Cupressus lusitanica Mill.), fertiliser (no fertiliser and nutrients supplied in excess of crop demands) and disturbance (low and high disturbance). These plots were harvested after 4 years and data was used to (i) examine treatment and site effects on volume mean annual increment (MAI) and (ii) identify key soil properties that influence volume MAI for the two species.Volume MAI significantly ranged 7-fold across sites. For the treatments, species accounted for most of the variance in volume MAI, with values for P. radiata significantly exceeding those of C. lusitanica by 95%. Volume MAI was significantly affected by fertilisation which induced gains of 33%. Disturbance did not significantly affect volume MAI. After correction had been made for climatic variables, soil properties that were most strongly related to volume MAI for both species included C:N ratio, total phosphorus (P), and organic P. When soil properties were included in combination, the best predictive models of volume MAI formulated for P. radiata included total P and C:N ratio while the best predictive model for C. lusitanica included C:N ratio and Olsen P. Variation in species sensitivity to total P and C:N ratio is likely to be attributable to their different mycorrhizal associations. For both species, the most important soil physical property influenced by management operations was total porosity. This research suggests that total P, C:N ratio, Olsen P and total porosity should be used as indicator properties for determining sustainability of plantation grown P. radiata and C. lusitanica. 相似文献
57.
58.
Unlu NZ Bohn T Francis D Clinton SK Schwartz SJ 《Journal of agricultural and food chemistry》2007,55(4):1597-1603
Tomato sauces were produced from unique tomato varieties to study carotenoid absorption in humans. Tangerine tomatoes, high in cis-lycopene, especially prolycopene (7Z,9Z,7'Z,9'Z), and high-beta-carotene tomatoes as an alternative dietary source of beta-carotene were grown and processed. Sauces were served after 2 week washout periods and overnight fasting for breakfast to healthy subjects (n = 12, 6M/6F) in a randomized crossover design. The serving size was 150 g (containing 15 g of corn oil), tangerine sauce containing 13 mg of lycopene (97.0% as cis-isomers) and high-beta-carotene sauce containing 17 mg of total beta-carotene (1.6% as the 9-cis-isomer) and 4 mg of lycopene. Blood samples were collected 0, 2, 3, 4, 5, 6, 8, and 9.5 h following test meal consumption and carotenoids determined in the plasma triacylglycerol-rich lipoprotein fraction by HPLC-electrochemical detection. Baseline-corrected areas under the concentration vs time curves (AUC) were used as a measure of absorption. AUC0-9.5h values for total lycopene in the tangerine sauce group were 870 +/- 187 (nmol.h)/L (mean +/- SEM) with >99% as cis-isomers (59% as the tetra-cis-isomer). The AUC0-9.5h values for total beta-carotene and lycopene after consumption of the high-beta-carotene sauce were 304 +/- 54 (4% as 9-cis-carotene) and 118 +/- 24 (nmol.h)/L, respectively. Lycopene dose-adjusted triacylglycerol-rich lipoprotein AUC responses in the tangerine sauce group were relatively high when compared to those in the literature and the high-beta-carotene group. The results support the hypothesis that lycopene cis-isomers are highly bioavailable and suggest that special tomato varieties can be utilized to increase both the intake and bioavailability of health-beneficial carotenoids. 相似文献
59.
Sridhar V Loope DB Swinehart JB Mason JA Oglesby RJ Rowe CM 《Science (New York, N.Y.)》2006,313(5785):345-347
Spring-summer winds from the south move moist air from the Gulf of Mexico to the Great Plains. Rainfall in the growing season sustains prairie grasses that keep large dunes in the Nebraska Sand Hills immobile. Longitudinal dunes built during the Medieval Warm Period (800 to 1000 years before the present) record the last major period of sand mobility. These dunes are oriented NW-SE and are composed of cross-strata with bipolar dip directions. The trend and structure of the dunes record a drought that was initiated and sustained by a historically unprecedented shift of spring-summer atmospheric circulation over the Plains: Moist southerly flow was replaced by dry southwesterly flow. 相似文献
60.