scholarly journals Spatial variation in the biochemical and isotopic composition of corals during bleaching and recovery

2018 ◽  
Author(s):  
Christopher B Wall ◽  
Raphael Ritson-Williams ◽  
Brian N Popp ◽  
Ruth D Gates
Keyword(s):  
Nitrogen Sources ◽  
Biomass Energy ◽  
Biomass Composition ◽  
Spatial And Temporal Variability ◽  
Total Biomass ◽  
Energy Reserves ◽  
Site Specific ◽  
Porites Compressa ◽  
Isotope Analyses ◽  
Nitrogen Demand

AbstractOcean warming and the increased prevalence of coral bleaching events threaten coral reefs. However, the biology of corals during and following bleaching events under field conditions is poorly understood. We examined bleaching and post-bleaching recovery inMontipora capitataandPorites compressacorals that either bleached or did not bleach during a 2014 bleaching event at three reef locations in Kāne‘ohe Bay, O‘ahu. We measured changes in chlorophylls, biomass, and nutritional plasticity using stable isotopes (δ13C, δ15N). Coral traits showed significant variation among bleaching conditions, reef sites, time periods, and their interactions. Bleached colonies of both species had lower chlorophyll and total biomass. WhileM. capitatachlorophyll and biomass recovered three months later,P. compressachlorophyll recovery was location-dependent and total biomass of previously bleached colonies remained low. Biomass energy reserves were not affected by bleaching, insteadM. capitataproteins andP. compressabiomass energy declined over time, andP. compressalipid biomass was site-specific. Stable isotope analyses of host and symbiont tissues did not indicate increased heterotrophic nutrition in bleached colonies of either species, during or after thermal stress. Instead, mass balance calculations revealed variance in δ13C values was best explained by augmented biomass composition, whereas δ15N values reflected spatial and temporal variability in nitrogen sources in addition to bleaching effects on symbiont nitrogen demand. These results emphasize total biomass quantity may change substantially during bleaching and recovery. Consequently, there is a need to consider the influence of biomass composition in the interpretation of isotopic values in corals.

scholarly journals The influence of riparian woodland on the spatial and temporal variability of stream water temperatures in an upland salmon stream

2004 ◽  
Vol 8 (3) ◽  
pp. 449-459 ◽  
Author(s):  
I. A. Malcolm ◽  
D. M. Hannah ◽  
M. J. Donaghy ◽  
C. Soulsby ◽  
A. F. Youngson
Keyword(s):  
Thermal Regime ◽  
Temporal Variability ◽  
Heat Budget ◽  
Riparian Forest ◽  
Stream Water ◽  
Spatial And Temporal Variability ◽  
Substantial Impact ◽  
Site Specific ◽  
The Impact ◽  
Riparian Woodland

Abstract. The spatio-temporal variability of stream water temperatures was investigated at six locations on the Girnock Burn (30km2 catchment), Cairngorms, Scotland over three hydrological years between 1998 and 2002. The key site-specific factors affecting the hydrology and climatology of the sampling points were investigated as a basis for physical process inference. Particular emphasis was placed on assessing the effects of riparian forest in the lower catchment versus the heather moorland riparian zones that are spatially dominant in the upper catchment. The findings were related to river heat budget studies that provided process detail. Gross changes in stream temperature were affected by the annual cycle of incoming solar radiation and seasonal changes in hydrological and climatological conditions. Inter-annual variation in these controlling variables resulted in inter-annual variability in thermal regime. However, more subtle inter-site differences reflected the impact of site-specific characteristics on various components of the river energy budget. Inter-site variability was most apparent at shorter time scales, during the summer months and for higher stream temperatures. Riparian woodland in the lower catchment had a substantial impact on thermal regime, reducing diel variability (over a period of 24 hours) and temperature extremes. Observed inter-site differences are likely to have a substantial effect on freshwater ecology in general and salmonid fish in particular. Keywords: temperature, thermal regime, forest, salmon, hydrology, Girnock Burn, Cairngorm

Simultaneous use of sodium nitrate and urea as nitrogen sources improves biomass composition ofArthrospira platensiscultivated in a tubular photobioreactor

2016 ◽  
Vol 16 (4) ◽  
pp. 338-347
Author(s):  
Ana Lucía Morocho-Jácome ◽  
Sunao Sato ◽  
Laís de Lara Capurro Guimarães ◽  
Camila Knysak Camargo de Jesus ◽  
João Carlos Monteiro de Carvalho
Keyword(s):  
Sodium Nitrate ◽  
Nitrogen Sources ◽  
Biomass Composition ◽  
Tubular Photobioreactor ◽  
Simultaneous Use

scholarly journals Social Cost of Biomass Energy from Switchgrass in Western Massachusetts

2013 ◽  
Vol 42 (1) ◽  
pp. 176-195 ◽  
Author(s):  
David Timmons
Keyword(s):  
Ecosystem Services ◽  
Forest Ecosystem ◽  
Production Cost ◽  
Social Cost ◽  
Benefit Transfer ◽  
Biomass Energy ◽  
Total Biomass ◽  
Forest Ecosystem Services ◽  
Private Cost ◽  
The Social

Producing biomass energy requires much land, and effects of biomass production on ecosystem services could greatly affect total biomass energy cost. This study estimates switchgrass production cost in western Massachusetts at three levels: private production cost, private cost plus social cost of nitrogen fertilizer externalities, and those costs plus the social opportunity cost of foregone forest ecosystem services. Values for nitrogen externalities and forest ecosystem services estimated with benefit transfer suggest that social cost is much greater than private switchgrass production cost. The benefit-transfer estimates are only first approximations, but conclusions are robust to a large range of values.

scholarly journals Denitrification and inference of nitrogen sources in the karstic Floridan Aquifer

2012 ◽  
Vol 9 (5) ◽  
pp. 1671-1690 ◽  
Author(s):  
J. B. Heffernan ◽  
A. R. Albertin ◽  
M. L. Fork ◽  
B. G. Katz ◽  
M. J. Cohen
Keyword(s):  
Noble Gas ◽  
Regional Scale ◽  
Isotopic Fractionation ◽  
Nitrogen Sources ◽  
Spatial And Temporal Variability ◽  
Limited Information ◽  
Nitrogen Budgets ◽  
Isotopic Signatures ◽  
Floridan Aquifer ◽  
Upper Floridan Aquifer

Abstract. Aquifer denitrification is among the most poorly constrained fluxes in global and regional nitrogen budgets. The few direct measurements of denitrification in groundwaters provide limited information about its spatial and temporal variability, particularly at the scale of whole aquifers. Uncertainty in estimates of denitrification may also lead to underestimates of its effect on isotopic signatures of inorganic N, and thereby confound the inference of N source from these data. In this study, our objectives are to quantify the magnitude and variability of denitrification in the Upper Floridan Aquifer (UFA) and evaluate its effect on N isotopic signatures at the regional scale. Using dual noble gas tracers (Ne, Ar) to generate physical predictions of N2 gas concentrations for 112 observations from 61 UFA springs, we show that excess (i.e. denitrification-derived) N2 is highly variable in space and inversely correlated with dissolved oxygen (O2). Negative relationships between O2 and δ15NNO3 across a larger dataset of 113 springs, well-constrained isotopic fractionation coefficients, and strong 15N:18O covariation further support inferences of denitrification in this uniquely organic-matter-poor system. Despite relatively low average rates, denitrification accounted for 32 % of estimated aquifer N inputs across all sampled UFA springs. Back-calculations of source δ15NNO3 based on denitrification progression suggest that isotopically-enriched nitrate (NO3–) in many springs of the UFA reflects groundwater denitrification rather than urban- or animal-derived inputs.

Site-specific assessment of spatial and temporal variability of sugarcane yield related to soil attributes

Geoderma ◽  
2019 ◽  
Vol 334 ◽  
pp. 90-98 ◽  
Author(s):  
Guilherme M. Sanches ◽  
Paulo S. Graziano Magalhães ◽  
Henrique C. Junqueira Franco
Keyword(s):  
Temporal Variability ◽  
Spatial And Temporal Variability ◽  
Site Specific ◽  
Soil Attributes ◽  
Sugarcane Yield ◽  
Specific Assessment

scholarly journals Denitrification and inference of nitrogen sources in the karstic Floridan Aquifer

2011 ◽  
Vol 8 (5) ◽  
pp. 10247-10294
Author(s):  
J. B. Heffernan ◽  
A. R. Albertin ◽  
M. L. Fork ◽  
B. G. Katz ◽  
M. J. Cohen
Keyword(s):  
Regional Scale ◽  
Negative Relationship ◽  
Isotopic Fractionation ◽  
Nitrogen Sources ◽  
Spatial And Temporal Variability ◽  
Limited Information ◽  
Nitrogen Budgets ◽  
Isotopic Signatures ◽  
Floridan Aquifer ◽  
Upper Floridan Aquifer

Abstract. Aquifer denitrification is among the most poorly constrained fluxes in global and regional nitrogen budgets. The few direct measurements of denitrification in groundwaters provide limited information about its spatial and temporal variability, particularly at the scale of whole aquifers. Uncertainty in estimates of denitrification may also lead to underestimates of its effect on isotopic signatures of inorganic N, and thereby confound the inference of N source from these data. In this study, our objectives are to quantify the magnitude and variability of denitrification in the Upper Floridan Aquifer (UFA) and evaluate its effect on N isotopic signatures at the regional scale. Using dual noble gas tracers (Ne, Ar) to generate physical predictions of N2 gas concentrations for 112 observations from 61 UFA springs, we show that excess (i.e. denitrification-derived) N2 is highly variable in space and inversely correlated with dissolved oxygen (O2). Negative relationship between O2 and δ15NNO3 across a larger dataset of 113 springs, well-constrained isotopic fractionation coefficients, and strong 15N : 18O covariation further support inferences of denitrification in this uniquely organic-matter-poor system. Despite relatively low average rates, denitrification accounted for 32% of estimated aquifer N inputs across all sampled UFA springs. Back-calculations of source δ15NNO3 based on denitrification progression suggest that isotopically-enriched nitrate (NO3−) in many springs of the UFA reflects groundwater denitrification rather than urban- or animal-derived inputs.

scholarly journals Biomass yield in production systems of soybean sown in succession to annual crops and cover crops

2017 ◽  
Vol 52 (8) ◽  
pp. 582-591 ◽  
Author(s):  
Leandro Pereira Pacheco ◽  
Andressa Selestina Dalla Côrt São Miguel ◽  
Rayane Gabriel da Silva ◽  
Edicarlos Damacena de Souza ◽  
Fabiano André Petter ◽  
...  
Keyword(s):  
Cover Crops ◽  
Production Systems ◽  
Pennisetum Glaucum ◽  
Block Design ◽  
Biomass Composition ◽  
Total Biomass ◽  
Crop Season ◽  
Yield Increase ◽  
Annual Crops ◽  
Tillage System

Abstract: The objective of this work was to evaluate the biomass (leaves and stems) production of annual and cover crops sown as second crop, and its effects on soybean yield in succession. The experiment was carried out in the 2014/2015 and 2015/2016 crop seasons. Soybean was sown in the crop season and in the second crop, in a randomized complete block design, in nine production systems (treatments) consisting of annual crops (corn, sunflower, and cowpea) and cover crops (Pennisetum glaucum, Crotalaria breviflora, C. spectabilis, Urochloa ruziziensis, Cajanus cajan, Stylosanthes sp., and U. brizantha), which were grown in monocropping or intercropping systems, besides fallow as a control. Monocropped P. glaucum and U. ruziziensis showed a faster establishment and growth of plants, higher-total biomass and soil cover rate in the 2014 crop season. In 2015, corn intercropped with U.ruziziensis and C.spectabilis, and sunflower with U.ruziziensis stood out for total biomass production during flowering and after harvesting of corn and sunflower grains. Biomass composition in the systems showed greater proportions of stems than of leaves, and C.spectabilis stood out after senescence. Sown as a second crop, C. spectabilis promotes yield increase of soybean grown in succession in the no-tillage system.

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