Genetic Differences May Help Corals Adapt to Changing Conditions | Marine Biology
 Individuals—even individuals of the same species—don’t always respond to a stimulus in the same way. Studying calcification in a key coral species, Acropora pulchra, researchers at the Moorea Coral Reef LTER found greater variety in the corals’ response to temperature than to high levels of CO2 in seawater. Since individual variation is the raw material of evolution, the contrast suggests it may be easier for this coral species to adapt to rising temperatures than to increased ocean acidification.
Previous studies of coral colonies have shown that ocean acidification and high temperatures can inhibit the deposition of calcium, known as calcification, that builds coral reef structure. The common garden experiment described here was designed specifically to examine whether individual colonies of Acropora pulchra responded in different ways to ocean warming and acidification.
In addition to greater variation in the response to temperature than CO2, the team also found that the fastest growing colonies under normal conditions were most affected by elevated temperature and CO2 levels. This implies that coral colonies contributing the most to reef growth will be disproportionately affected by changing environmental conditions.
—Erin O'Reilly
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Cold Air Drainage Flows Subsidize Montane Valley Ecosystem Productivity | Global Change Biology
 Landscape ecologists and nature-lovers are well aware of the way that valleys collect deeper, moister soils than neighboring hill slopes and crests. Now, researchers at Coweeta LTER have have found that cool air, sliding downslope from higher elevations and pooling in mountain valleys, subsidizes productivity in a different way. The cold air drainage was most prevalent at night and in the evenings, so it had little effect on photosynthesis, but reduced plant and soil respiration by about 8 percent. Overall, the authors estimate it boosted annual net carbon uptake by about 15 percent.
The study, published in December’s issue of Global Change Biology, drew on data from several long-running climate stations and eddy covariance flux towers within the Coweeta Experimental Forest, direct measures of temperatures and respiration in both soils and leaves, comparison to eddy covariance measures at the nearby Duke Forest Hardwood Site Ameriflux Tower, and recent improvements in the interpretation of eddy covariance data in complex terrain.
The authors note that the drainage effect was, somewhat unexpectedly, strongest during dry weather. As periods of drought are expected to increase under climate change, the subsidy could represent a previously unexamined climate feedback.
—Marty Downs
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Arctic Communities See Access Challenges Ahead | Climate Change
 Climate-change is predicted to have a larger impact on Arctic regions than on temperate ecosystems. As a result, rural communities relying on local wild resources, or subsistence harvesting, are vulnerable to climate-change-induced environmental trends affecting the availability of fish, waterfowl, and other key resources. The availability of such resources is determined by their abundance, distribution, and accessibility to harvesters. In collaboration with communities in Alaska, a recent study based at Bonanza Creek LTER found that access to resources—rather than resource distribution or abundance—most heavily impacted resource availability as a result of changes in climate.
As this study emphasizes, understanding the root cause of an issue is critical in effectively managing its impacts. For example, scientific climate projections forecasted a net reduction in available subsistence resources over the next 30 years in the Arctic region. However, the models did not consider accessibility, which, if included, would further reduce projections of available subsistence resources for Arctic communities.
—Alina Werth
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Climate Variability Predicted to Affect Outcome of Exotic Grass Invasion | Ecohydrology
 Novel ecosystems can emerge through many kinds of changes, including changes in mean climate, species invasions, and increased or decreased variability. Researchers at Jornada Basin LTER have highlighted the role of interannual climate variability in changing the outcome when an exotic grass species invades dry shrubland. Using a process-based model, they predicted three outcomes, depending on the degree of variability and timing relative to invasion.
Nonnative, highly flammable, grasses frequently invade shrubland ecosystems, increasing the chance of wildfire and mortality for native shrubs that are not adapted to fire conditions. Under relatively static conditions, the exotic grass dominates. However, with increasing climate variability in arid and semiarid regions, their model shows that grasses are less likely to achieve a steady state within the ecosystem. If severe droughts occur while shrubs can still re-establish, they may remain dominant in their native habitat. Alternatively, if these drought conditions occur after a shrubland has already been converted by invasive grasses, the system could crash, resulting in a die-off of the present grass vegetation.
This unvegetated succession stage could lead to increased runoff and loss of soil resources. The model demonstrates the concept of environmental variability leading to a dichotomous result, two possible shrubland states.
—Madison Harris
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Finding the Hidden Phytoplankton Blooms | Inland Waters
In stratified lakes, a large portion of phytoplankton biomass is found—not at the surface, where sampling is easiest—but somewhere down the water column, in what is known as a subsurface chlorophyll maximum (SSCM). Researchers in Global Lake Ecological Observatory Network (GLEON) compared automated high-frequency chlorophyll fluorescence (ChlF) profiles with surface samples and discrete depth profiles. In 7 of the 11 lakes studied, automated sampling captured the presence of SSCM’s that would have been missed by conventional sampling.
These hidden blooms of phytoplankton can comprise up to 70% of the productivity in low-nutrient lakes and can come and go within days and move up and down the water column within hours. The new research is helping to motivate an update of the Plankton Ecology Group (PEG) model to include physical parameters, which can determine the strength, location and duration of such sub-surface blooms.
—Marty Downs
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ILTER Nitrogen Initiative
The ILTER Nitrogen Initiative put on a well-received training in 2016 and is planning another training for 2017 in Lisbon, Portugal; an N2O workshop in Taiwan; and a special issue of the journal Science of the Total Environment. Visit the Nitrogen Initiative's full report on lternet.edu for more details.
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