Total live mangrove coverage and annual NDVI classifications for the mangrove die-off region based on Landsat 5 and 7 transformed imagery.

Dataset: Live area and NDVI measurementsThese data were compiled to better determine when the mangrove die-off began. NDVI values of 0.2 or greater correspond to live mangrove cover. These data suggest the mangrove die-off may have started in 2008 and was exacerbated in following years with some recovery in 2013. Live area was calculated by determining the area of the die-off region with NDVI values greater than 0.2. For a complete list of measurements, refer to the supplemental document 'Field_names.pdf', and a full dataset description is included in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: http://www.bco-dmo.org/dataset/720270NSF Division of Ocean Sciences (NSF OCE) OCE-154163

Can biodiversity of preexisting and created salt marshes match across scales? An assessment from microbes to predators

Coastal wetlands are rapidly disappearing worldwide due to a variety of processes, including climate change and flood control. The rate of loss in the Mississippi River Delta is among the highest in the world and billions of dollars have been allocated to build and restore coastal wetlands. A key question guiding assessment is whether created coastal salt marshes have similar biodiversity to preexisting, reference marshes. However, the numerous biodiversity metrics used to make these determinations are typically scale dependent and often conflicting. Here, we applied ecological theory to compare the diversity of different assemblages (surface and below-surface soil microbes, plants, macroinfauna, spiders, and on-marsh and off-marsh nekton) between two created marshes (4–6 years old) and four reference marshes. We also quantified the scale-dependent effects of species abundance distribution, aggregation, and density on richness differences and explored differences in species composition. Total, between-sample, and within-sample diversity (γ, β, and α, respectively) were not consistently lower at created marshes. Richness decomposition varied greatly among assemblages and marshes (e.g., soil microbes showed high equitability and α diversity, but plant diversity was restricted to a few dominant species with high aggregation). However, species abundance distribution, aggregation, and density patterns were not directly associated with differences between created and reference marshes. One exception was considerably lower density for macroinfauna at one of the created marshes, which was drier because of being at a higher elevation and having coarser substrate compared with the other marshes. The community compositions of created marshes were more dissimilar than reference marshes for microbe and macroinfauna assemblages. However, differences were small, particularly for microbes. Together, our results suggest generally similar taxonomic diversity and composition between created and reference marshes. This provides support for the creation of marsh habitat as tools for the maintenance and restoration of coastal biodiversity. However, caution is needed when creating marshes because specific building and restoration plans may lead to different colonization patterns

Testing sample stability using four storage methods and the macroalgae Ulva and Gracilaria

Concern over the relative importance of different sample preparation and storage techniques frequently used in stable isotope analysis of particulate nitrogen (δ15N) and carbon (δ13C) prompted an experiment to determine how important such factors were to measured values in marine organisms. We stored the marine macroalgae Ulva and Gracilaria in four different ways and analyzed replicates every three months over the course of a year to assess treatment effects on stability. Treatments consisted of algae dried at 65°C, ground to a powder, and stored in a desiccator until analysis; algae left in a drying oven or in a freezer and processed (dried and ground) just prior to analysis, as well as some dried, ground samples kept out in the lab and reanalyzed quarterly for 12 months. Concurrently, to assess the ecological range in isotope values over the course of a year, samples were freshly collected from the same location and analyzed along with the other treatments at each time step. Neither storage technique nor time had an impact on either δ15N or δ13C values or the %N and %C of the algae tissues. There were clear and consistent differences between species and some large seasonal differences in the freshly collected samples. The interspecies differences and seasonal ranges of values underscore the stability associated with method and duration of sample storage

Decomposition of mangrove litter under experimental nutrient loading in a fringe Rhizophora mangle (L.) forest

Carbon (C) cycling is an important attribute of mangrove forests that relates to the structure, function, and resilience of mangroves under environmental change. Increased nutrient enrichment in tropical coastal waters may influence C cycling through organic C mineralization. For example, by alleviating nutrient limitation of the heterotrophic microbial community, nutrient enrichment may enhance C mineralization and facilitate a loss of within-stand C sequestration. Here, we enriched a coastal fringe Rhizophora mangle (L.) mangrove system for two years with two fertilizer regimes to mimic agriculture runoff (”+high” N:P ratio of 50:1) and urban runoff (”+moderate” N:P ratio of 16:1) scenarios as follows: (1) annual loading rate of 70 g N m −2 year −1 and 3.1 g P m −2 year −1 or (2) annual loading rate of 70 g N m −2 year −1 and 9.7 g P m −2 year −1. C mineralization was measured as microbial respiration rates from the forest floor and litter decomposition rates. While decomposing leaf litter and green leaves had lower molar C:N under the +moderate N:P fertilization course, neither fertilization scenario produced an effect on C mineralization processes compared with ambient conditions. Substrate CO 2 flux rates were not different among treatments and ranged from 1.15 to 1.81 μmol CO 2 m −2 s −1 (3.0–4.8 g CO 2 m −2 day −1) following 72 weeks of fertilization and 0.58–1.55 μmol CO 2 m −2 s −1 (1.5–4.1 g CO 2 m −2 day −1) 30 weeks following the end of the experiment. Time to 50% decay of above-ground leaf litter ranged from 61 to 110 days (average 79 days). Below-ground leaf litter material was fully decomposed by 22 months after burial. A15 N pulse-recovery suggests that the majority of the retained fertilizer (22.2 ± 4.4% at 10 months following spike) was taken up by fine roots, though this did not significantly affect CO 2 flux from the forest floor. This work demonstrates that nutrient enrichment by aqueous delivery does not strongly affect organic carbon mineralization in a coastal fringe mangrove within two years. Environmental conditions, substrate quality, and location may play a more substantial role in mangrove C dynamics compared with short-term aqueous-based nutrient enrichment

A Primer on the History of Food Web Ecology: Fundamental Contributions of Fourteen Researchers

ABSTRACT Food webs are one of the primary frameworks on which the ecological sciences have been built. Research in this field has burgeoned over recent decades, expanding into diverse sub-disciplines and employing many different methodological approaches. Here we structure a historical review around 14 researchers and the specific contributions they have made to the field. Beginning with Charles Elton's insights into food web structure, and continuing to contemporary ecologists and emerging areas of study, we highlight some of the most important empirical and theoretical advances made over the last century. The review highlights that there are fundamentally different ways in which food webs are depicted and studied. Specifically, when one views systems through mathematical, energy flow or functional lenses, very different perspectives on food web structure and dynamics emerge. The contributions of these scientists illustrate the considerable advances that the field has undergone, and they provide the foundation for expansive on-going research programs that fall under the broad umbrella of food web ecology