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News Article | May 11, 2017

DURHAM, N.C. -- Stronger and more frequent hurricanes may pose a new threat to the sooty tern, an iconic species of migratory seabird found throughout the Caribbean and Mid-Atlantic, a new Duke University-led study reveals. The study, published this week in the peer-reviewed open-access journal PeerJ, is the first to map the birds' annual migratory path and demonstrate how its timing and trajectory place them in the direct path of hurricanes moving into the Caribbean after forming over the Atlantic. "The route the birds take and that most Atlantic-forming hurricanes take is basically the same, only in reverse," said Ryan Huang, a doctoral student at Duke's Nicholas School of the Environment, who led the study. "That means these birds, who are usually very tired from traveling long distances over water without rest, are flying head-on into some of the strongest winds on the planet." "This is worrying because we know that as Earth's climate changes, we expect to see more frequent and powerful hurricanes in the future -- meaning that the chances of sooty terns being hit by storms will likely go up," Huang said. Hurricane season typically lasts from June to November, with peak activity occurring in August and September. A new map produced by the research shows that sooty terns leave their breeding colony at Dry Tortugas National Park in the Florida Keys each June as hurricane season starts. They migrate southward and eastward across the Caribbean through summer and early fall, before skirting the northern coast of South America and arriving at their winter habitat off the Atlantic coast of Brazil in November. Huang and his colleagues charted the migratory path by recording and mapping the dates and locations of all sooty terns banded for study at the Dry Tortugas since the 1950s but found dead elsewhere. They also mapped locational data retrieved from birds that were fitted with satellite-telemetry tracking tags. When they overlaid all this data with maps of hurricane paths from the same period, they discovered a striking correlation. "While it's impossible to say just how many of the birds died as a direct result of the hurricanes, we saw a strong relationship between the numbers and locations of bird deaths and the numbers and locations of hurricanes," said Stuart L. Pimm, the Doris Duke Professor of Conservation Ecology at Duke's Nicholas School. "What's really interesting is that it's not just the big category 4 and 5 storms that can kill large numbers of birds. A series of smaller, weaker storms may have the same impact as that of a single large, strong storm," Pimm noted. "In September 1973, Tropical Storm Delia, a small storm in the Gulf of Mexico, killed a lot of birds because they were in the wrong place at the wrong time." Although sooty terns are neither rare nor endangered -- 80,000 or more of them are estimated to breed in the Dry Tortugas each year -- they have long been used by scientists as an indicator species to determine the health of the region's marine environment. "If there are changes taking place in the ocean, you'll see corresponding changes taking place in the health of these tern populations, among other indicator species," Huang said. "That's what makes our findings somewhat concerning. If these birds are experiencing negative effects from changing ocean conditions, they are unlikely to be the only species affected." Oron L. Bass Jr. of the South Florida Natural Resources Center at Everglades National Park co-authored the new study with Huang and Pimm. Funding came from the National Park Service and the National Science Foundation Graduate Research Fellowship program.

Surratt D.,National Park Service | Shinde D.,South Florida Natural Resources Center | Aumen N.,National Park Service
Environmental Management | Year: 2012

Recent appearance of cattail (Typha domingensis) within a southern Everglades slough-Upper Taylor Slough (Everglades National Park)-suggests ecosystem eutrophication. We analyze water quality, nutrient enrichment, and water management operations as potential drivers of eutrophication in Upper Taylor Slough. Further, we attempt to determine why surface water phosphorus, a parameter used commonly to monitor ecosystem health in the Everglades, did not serve as an early warning for eutrophication, which has broader implication for other restoration efforts. We found that surface water total phosphorus concentrations generally were below a 0.01 mg L-1 threshold determined to cause imbalances in flora and fauna, suggesting no ecosystem eutrophication. However, assessment of nutrient loads and loading rates suggest Upper Taylor Slough has experienced eutrophication and that continued total phosphorus loading through a pointsource discharge was a major driver. These nutrient loads, combined with increases in hydroperiods, led to the expansion of cattail in Upper Taylor Slough. We recommend other metrics, such as nutrient loads, periphyton and arthropod community shifts, and sediment core analyses, for assessing ecosystem health. Monitoring surface water alone is not enough to indicate ecosystem stress. © Springer Science+Business Media, LLC.

News Article | April 27, 2016

EVERGLADES NATIONAL PARK, Florida — The shallow coastal waters of Florida Bay are famed for their crystal clear views of thick green seagrass – part of the largest stretch of these grasses in the world. But since mid-2015, a massive 40,000-acre die off here has clouded waters and at times coated shores with floating dead grasses. The event, which has coincided with occasional fish kills, recalls a prior die-off from 1987 through the early 1990s, which spurred major momentum for the still incomplete task of Everglades restoration. “It actually started faster as far as we can tell this year,” said James Fourqurean, a Florida International University marine scientist who studies the system. “In the ’80s, it continued to get worse for 3 years.” Fourqurean and government Everglades experts fear they’re witnessing a serious environmental breakdown, one that gravely threatens one of North America’s most fragile and unusual wild places. When most people think of the Everglades, they envision swamps — but seagrass is just as important, if less romanticized. Besides being the home to majestic sea turtles, dolphins, and manatees, Florida Bay also hosts pink shrimp, spiny lobsters, spotted seatrout, and much more – sport fishing alone here is worth $ 1.2 billion per year, according to the Everglades Foundation. And although there is at least some scientific dissent, Fourqurean and fellow scientists think they know the cause of the die-off. It’s just the latest manifestation, they say, of the core problem that has bedeviled this system for many decades: Construction of homes, roads, and cities has choked off the flow of fresh water. Without fast moves to make the park far more resilient to climate change and rising, salty seas, the problem will steadily worsen. The Everglades ecosystem “being out of balance at a time of climate change is really going to have a huge impact on South Florida, if we don’t do something about it,” said Interior Secretary Sally Jewell, who surveyed the seagrass die-off last week during an Everglades Trip. Holding dead grasses in her hand in a National Park Service boat in the more than half-a-million-acre estuary, Jewell told a group of staff and reporters, “This is what we get when we don’t take care of Florida Bay.” Florida Bay encompasses roughly one-third of Everglades National Park. And like the park’s mangroves and sawgrass prairies, it relies on the same broad water system. Both need fresh water to flow southward from Florida’s Lake Okeechobee, and the central part of the state, to preserve their unique characteristics. And both have suffered from highway and water management projects that have blocked or diverted much of this water away. “It’s basically a permanent manmade drought, created by the drainage and development patterns to the north in the Everglades,” said Robert Johnson, director of the National Park Service’s South Florida Natural Resources Center, on the boat trip with Jewell. The seagrass die off, according to Johnson, was caused when this perennial problem was further exacerbated by a 2014-2015 South Florida drought. Flows through Shark River Slough, which feeds water to the Everglades and eventually Florida Bay, plunged to just 200,000 acre-feet in 2015. That’s just a quarter of standard annual flows, which themselves are less than half of historic flows of 2 million acre-feet per year before major projects blocked and redirected the Everglades’ water. The center of the bay then heated up last summer, saw considerable evaporation, and became quite salty – for some parts of the bay, twice as salty as normal sea water. “It’s a really delicate balance between how much freshwater comes in each year, how much rainfall falls, and then how much evaporation occurs,” Johnson said. “In the absence of rainfall, salinity takes off in the bay, and we get a lot of harmful impacts of that.” In very salty conditions, waters hold little of the oxygen that seagrasses need to live. At the same time, other marine organisms turn to a different “anoxic” process – one that goes forward without oxygen – that has a nasty by-product: hydrogen sulfide. The chemical “is a notorious toxin,” said Donald Boesch, president of the University of Maryland Center for Environmental Science. “It kills life, including human.” And that’s just the beginning. Once the seagrass dies off, it becomes a feedback – the water becomes filled with dead grasses that release nutrients, and those can stoke huge algal blooms (which happened the last time around, but so far have not appeared en masse). That clouds the water and prevents light from reaching remaining seagrasses, which then also die, because they need the light for photosynthesis. “You have this water that’s notoriously gin clear water, because the seagrasses and the biology kept the light penetrating, and then all of a sudden it changes pretty dramatically to a system without grass, and very turbid waters,” Boesch said. Granted, there are some dissenters. Brian LaPointe, a researcher with Florida Atlantic University, contends that Florida Bay seagrass die-offs are caused by the runoff of too many nutrients, like nitrogen, into the Bay’s waters, which in turn stoke algal blooms. “There really isn’t a correlation over time of high salinity and problems in the Bay,” LaPointe said. Seagrasses, he said, “can handle pretty high salinities.” During the last dieoff, a large scientific debate erupted over whether changes in salinity were indeed the cause. But Boesch, who led a scientific review of the last die-off during the Clinton administration (which failed to reach a conclusion at the time), said that the high-salinity explanation “has now become kind of the mainstream scientific explanation,” although that now encompasses other related processes involving oxygen content of waters and buildup of hydrogen sulfide. It’s not just Florida Bay: Seagrasses the world over are threatened. In a 2009 study, scientists found that segrass extent had declined globally by 29 percent since the late 19th century. They concluded that seagrasses were just as threatened as their companion coastal ecosystem, coral reefs, though the latter tend to get far more attention. The Obama administration, in collaboration with Florida state agencies and local leaders, has been moving lately to simultaneously restore historic Everglades water flows and to try to safeguard the park against climate change. President Obama visited last year, telling his audience that “You do not have time to deny the effects of climate change…nowhere will it have a bigger impact than here in South Florida.” And this year Jewell visited the Everglades on Earth Day to announce a $ 144 million “bridging” project that will elevate 2.5 miles of Highway 41, more popularly known as the Tamiami Trail, which connects Miami to Tampa and runs through the Everglades. Constructed in the 1920s, the highway impairs water flow southward, from Lake Okeechobee, into the Everglades (and, eventually, the Bay). It’s like a dam across the famed “river of grass.” Lifting it could restore a substantial part of historic freshwater flow levels. But that will take years – the project should be completed in 2020 — too long to stop the current seagrass die off from running its course and perhaps having many cascading effects, scientists fear. And it’s not just nature that needs this fresh water: It’s people. South Florida, the home to 6 million people now and growing steadily, relies on the Biscayne aquifer, which is refilled by the Everglades, for drinking water. The aquifer’s water flows through limestone that is quite porous, which means that saltwater and freshwater can both penetrate it. In effect, two walls of water abut one another, facing off — and for the sake of nature and people alike, freshwater needs to hold its ground. If inadequate freshwater flows southward in Florida, then Florida Bay can get too salty even as the seas also creep into the Everglades, potentially causing land to subside and sink – but also penetrating the aquifer and threatening drinking water. In short, it’s bad news across the whole system. And even as governments at the local, state, and national level move faster to send the Everglades and the Bay more fresh water, the question remains just how much climate change will worsen problems like the seagrass die-off. After all, it will raise seas, increase air and water temperatures, and perhaps drive more droughts as well. “The questions I would ask, from a climate perspective, going forward, is first of all, are we going to have more conditions of really high temperature, due to, you know, the atmospheric warming, coupled with these extended periods of still water?” Boesch said. “Are we going to have longer periods of drought in the Everglades?” Boesch said that while higher temperatures are a given, precipitation patterns are difficult to predict, but notes that there is some reason to fear South Florida could get drier in the future. “What happened to the Bay is very much a climate change issue,” Jewell said in an interview during her Everglades tour. “It’s tied in to a drought. Now, is the drought tied to climate change? None of us could tie any single hurricane or storm event or drought to climate change, but we do know that the weather here is getting more extreme. And we do know that those extreme weather patterns are having a dramatic impact on our ecosystems, as we saw today on Florida Bay.” Still, much of Florida Bay remains unaffected – for now. That includes an area of lush seagrass meadow near a small island named Johnson Key. A trio of bottlenosed dolphins approached the National Park Service skiff there, and as the boat trolled slowly through the clear, only 3- to 4-foot-deep water, started to lead the way ahead of it. Nonetheless, the second major seagrass die off in three decades certainly suggests that something has changed recently in the system. “The really disturbing thing is, this unprecedented event has now happened twice in my career,” Fourqurean said. Six years later, we’re still learning how badly the BP spill damaged the environment This key psychological factor could explain why you care about the environment These striking numbers show just how fast we’re switching off coal For more, you can sign up for our weekly newsletter here, and follow us on Twitter here.

Cheng Y.,Georgia Institute of Technology | Stieglitz M.,Georgia Institute of Technology | Turk G.,Georgia Institute of Technology | Engel V.,South Florida Natural Resources Center
Geophysical Research Letters | Year: 2011

Wetland ecosystems are often characterized by distinct vegetation patterns. Various mechanisms have been proposed to explain the formation of these patterns; including spatially variable peat accumulation and water ponding. Recently, short-range facilitation and long-range competition for resources (a.k.a scale dependent feedback) has been proposed as a possible mechanism for pattern formation in wetland ecosystems. We modify an existing, spatially explicit, advection-reaction-diffusion model to include for a regional hydraulic gradient and effective anisotropy in hydraulic conductivity. This effective anisotropic hydraulic conductivity implicitly represents the effect of ponding: a reduction in the long-range inhibition of vegetation growth in the direction perpendicular to the prevailing hydraulic gradient. We demonstrate that by accounting for effective anisotropy in a simple modeling framework that encompasses only a scale dependent feedback between biomass and nutrient flow, we can reproduce the various vegetation patterns observed in wetland ecosystems: maze, and vegetation bands both perpendicular and parallel to prevailing flow directions. We examine the behavior of this model over a range of plant transpiration rates and regional hydraulic gradients. Results show that by accounting for the effective x-y anisotropy that results from biomass-water interaction (i.e., ponding) we can better understand the mechanisms that drive ecosystem patterning. Copyright © 2011 by the American Geophysical Union.

Seavey F.,South Florida Natural Resources Center | Seavey J.,South Florida Natural Resources Center
Bryologist | Year: 2012

We report the results of recently investigated collections from Everglades National Park and Biscayne National Park that have yielded several new additions to the North American lichen checklist, and Caloplaca lecanorae, a new lichenicolous lichen found on the thallus of Lecanora leprosa. Those species new to North America include Arthonia compensatula, A. ochrospila, Bacidina pallidocarnea, Byssoloma absconditum, Coenogonium isidiigerum, C. isidiosum, Enterographa pallidella, Lecanora hypocrocina, L. tropica, Monoblastia palmicola and Parmotrema wrightii. Both Lecanora species have been reported from Mexico, which is excluded from the aforementioned checklist. © 2012 The American Bryological and Lichenological Society, Inc.

Seavey F.,South Florida Natural Resources Center | Seavey J.,South Florida Natural Resources Center
Bryologist | Year: 2014

Our continuing investigation of lichen collections within Everglades National Park have revealed four new species to science, Cryptothecia fuscopunctata, Diorygma basinigrum, Herpothallon hyposticticum and Platygramme coccinea. In addition, the following 16 taxa are reported for the first time to the continent north of Mexico: Coenogonium isidiatum, C. isidiiferum, C. nepalense, C. subdilutum, Enterographa subserialis, Fellhanera rhapidophylli, Malmidea flavopustulosa, Melanotrema platystomum, Phyllopsora labriformis, Pyrenula dissimulans, P. minor, P. parvinuclea, P. pleiomera, Ramalina leptosperma, Sclerophyton seriale and the lichenicolous fungi Labrocarpon canariensis encountered on Ochrolechia africana. A brief discussion comparing richness and density of the corticolous Everglades lichen flora with that of Central and South America lowland tropical forests is presented. © The American Bryological and Lichenological Society, Inc.

Seavey F.,South Florida Natural Resources Center | Seavey J.,South Florida Natural Resources Center
Lichenologist | Year: 2015

During 2010-12 collecting seasons, we visited 27 islands, locally called keys, in Florida Bay within the boundaries of Everglades National Park for the purpose of investigating their lichen flora. A disproportionate number of the resultant collections belong to Enterographa Fée, a genus mostly tropical in distribution. Currently, 11 species are known from Everglades National Park, of which Enterographa bradleyana, E. caudata, E. murrayana and E. nitidula are described here as new to science. Enterographa bradleyana is superificially similar to Enterographa divergens but has smaller ascospores, a wider perispore and contains gyrophoric acid. Enterographa candata is easily identified by an unusual chemistry of lichexanthone and schizopeltic acid and its extremely long tailed ascospores. Enterographa murrayana resembles E. anguinella in the field but has a different chemistry, wider ascospores with more septation and a wider perispore. Enterographa nitidula has an unusual fine powdery and glossy thallus, small 4-celled ascospores and contains an unidentified substance. Because a large number of Enterographa have been described (20 including those newly described here) since Sparrius monographed the genus in 2004, an updated world key to the genus is provided. © British Lichen Society 2014.

Kotun K.,South Florida Natural Resources Center | Renshaw A.,South Florida Natural Resources Center
Wetlands | Year: 2014

Taylor Slough, in Everglades National Park, has experienced an evolution of water management infrastructure since drainage activities arrived in South Florida. This has included the excavation of canals, installation of large capacity pump stations, and a variety of operational strategies focused on resolving the conflict between managing the water level for developed areas while providing water supply for Everglades National Park. This study provides a review of water management practices and the concurrent hydrologic conditions in the Taylor Slough basin and adjacent canal system from 1961 through 2010. Analyses of flow, water level and rainfall data were divided into time periods that correspond to significant changes in structural features and operational plans. In the early 1960s, Taylor Slough was disconnected from the greater Everglades system by the construction of levees upstream. As water supply for Taylor Slough became more urgent, the Slough was connected to the regional water supply system via a network of canals and pump stations to relieve over-drained conditions. The increased water supply and pump capacity succeeded in raising water level and increasing flow and hydroperiod in the marsh. © Society of Wetland Scientists 2013.

Seavey F.,South Florida Natural Resources Center | Seavey J.,South Florida Natural Resources Center
Bryologist | Year: 2011

In this paper we reassess 482 collections of the lichen genus Graphis from Everglades National Park using the recent world key of Lcking and co-workers as the principal reference. We report a total of 31 species present in the Park. Of these, three species, Graphis brittoniae, G. elevata and G. hinnulea, are described as new to science. In addition, the following eleven species are newly reported from North America: Graphis analoga Nyl., G. cincta (Pers.) Aptroot, G. chlorotica A. Massal., G. crebra Vain., G. dendrogramma Nyl., G. filiformis Adaw. & Makhija, G. furcata Fe, G. modesta Zahlbr., G. neoelongata Zenker, G. renschiana (Mll. Arg.) Stizenb. and G. supracola A. W. Archer. Each species is described and discussed based upon Park collections. Notes concerning some species previously known from North America are also included where new or interesting information can be added to the literature. Conversely, species well documented elsewhere where we have nothing to add are excluded from that section. Graphis chlorotica, also new to North America but collected from outside the Park, is treated here since the key would be incomplete with its omission. Photos of all 32 species are provided including the degree of excipular carbonization. A key is provided for all species of Graphis known to occur in Florida. © 2011 The American Bryological and Lichenological Society, Inc.

Seavey F.,South Florida Natural Resources Center
Bryologist | Year: 2010

Although Cladonia cinerella Ahti does not appear on the North American checklist of lichens and lichenicolous fungi, it was collected once from the Everglades of Florida in 1909. Ironically, I encountered a large colony deep within the interior of Everglades National Park exactly one century plus one day after the original encounter. In this paper I present some additional observations to Ahti's description based upon living Everglades material illustrated by photos and propose the addition of C. cinerella to the above checklist. © 2010 The American Bryological and Lichenological Society, Inc.

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