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Articles 1 - 4 of 4
Full-Text Articles in Earth Sciences
Using Stable Isotope Analyses To Assess The Trophic Ecology Of Scleractinian Corals, Michael P. Lesser, Marc Slattery, Keir J. Macartney
Using Stable Isotope Analyses To Assess The Trophic Ecology Of Scleractinian Corals, Michael P. Lesser, Marc Slattery, Keir J. Macartney
School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations
Studies on the trophic ecology of scleractinian corals often include stable isotope analyses of tissue and symbiont carbon and nitrogen. These approaches have provided critical insights into the trophic sources and sinks that are essential to understanding larger-scale carbon and nitrogen budgets on coral reefs. While stable isotopes have identified most shallow water (<30 m) corals as mixotrophic, with variable dependencies on autotrophic versus heterotrophic resources, corals in the mesophotic zone (~30–150 m) transition to heterotrophy with increasing depth because of decreased photosynthetic productivity. Recently, these interpretations of the stable isotope data to distinguish between autotrophy and heterotrophy have been criticized because they are confounded by increased nutrients, reverse translocation of photosynthate, and changes in irradiance that do not influence photosynthate translocation. Here we critically examine the studies that support these criticisms and show that they are contextually not relevant to interpreting the transition to heterotrophy in corals from shallow to mesophotic depths. Additionally, new data and a re-analysis of previously published data show that additional information (e.g., skeletal isotopic analysis) improves the interpretation of bulk stable isotope data in determining when a transition from primary dependence on autotrophy to heterotrophy occurs in scleractinian corals.
Identifying Nitrogen Source And Seasonal Variation In A Black Mangrove (Avicennia Germinans) Communityof The South Texas Coast, Ashley Elizabeth Murphy, Carlos E. Cintra-Buenrostro, Alejandro Fierro-Cabo
Identifying Nitrogen Source And Seasonal Variation In A Black Mangrove (Avicennia Germinans) Communityof The South Texas Coast, Ashley Elizabeth Murphy, Carlos E. Cintra-Buenrostro, Alejandro Fierro-Cabo
School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations
Black mangrove (Avicennia germinans) stands in south Texas grow in association with other autotrophic organisms including herbaceous halophytes and cyanobacterial mats. Despite the relevant ecosystem services provided by this coastal plant community, limited information exists on its functioning, in particular as it pertains to nutrient dynamics, namely nitrogen (N). Nitrogen stable isotopes were used to assess potential N sources for plant growth in this community. Plant tissue (leaves), cyanobacteria, and sediment were sampled once every season for one year. Total N in A. germinans (2.6 %) and associated saltwort (Batis maritima) (2.1 %) was higher than in cyanobacteria (0.6 %), …
Decomposition And Nitrogen Dynamics Of Turtle Grass (Thalassia Testudinum) In A Subtropical Estuarine System, Monica Delgado
Decomposition And Nitrogen Dynamics Of Turtle Grass (Thalassia Testudinum) In A Subtropical Estuarine System, Monica Delgado
Theses and Dissertations
Seagrass beds are pivotal in the functioning of coastal ecosystems in terms of productivity, organic matter turnover and nutrient cycling. Aiming to document decay and nitrogen (N) dynamics of turtle grass (Thalassia testudinum) in a subtropical estuarine system, decomposition patterns of leaves and rhizomes were characterized and compared. Nitrogen usage during decomposition of tissues, and of live tissues and epiphytes growing on live leaves, was also quantified and compared. Stable isotope ratios allowed tracing N within the seagrass bed, following N incorporation into seagrass tissues from the surrounding media (water, sediment). Leaves had a higher N content and decomposed at …
Iron-Mediated Stabilization Of Soil Carbon Amplifies The Benefits Of Ecological Restoration In Degraded Lands, Lucas C. R. Silva, Timothy A. Doane, Rodrigo S. Correa, Vinicius Valverde, Engil Isadora Pujol Pereira, William R. Horwath
Iron-Mediated Stabilization Of Soil Carbon Amplifies The Benefits Of Ecological Restoration In Degraded Lands, Lucas C. R. Silva, Timothy A. Doane, Rodrigo S. Correa, Vinicius Valverde, Engil Isadora Pujol Pereira, William R. Horwath
School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations
Recent observations across a 14‐year restoration chronosequence have shown an unexpected accumulation of soil organic carbon in strip‐mined areas of central Brazil. This was attributed to the rapid plant colonization that followed the incorporation of biosolids into exposed regoliths, but the specific mechanisms involved in the stabilization of carbon inputs from the vegetation remained unclear. Using isotopic and elemental analyses, we tested the hypothesis that plant‐derived carbon accumulation was triggered by the formation of iron‐coordinated complexes, stabilized into physically protected (occluded) soil fractions. Confirming this hypothesis, we identified a fast formation of microaggregates shortly after the application of iron‐rich biosolids, …