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News Article | November 17, 2016
Site: www.eurekalert.org

For the first time, Smithsonian researchers and collaborators have designed a marine reserve network to protect species threatened by overfishing while boosting fishing yields on nearby fishing grounds, resolving a long-standing global "conserve or catch" conflict in marine conservation efforts. A team led by scientists from the Smithsonian's Marine Conservation Program report in the journal Conservation Letters Nov. 17 that they have designed a model network of marine reserves off the Caribbean coast of Honduras, which can support the long-term preservation of spiny lobsters within the country's waters while also increasing fishing yields of the species in fishing areas outside the reserves' borders. "Placing marine reserves across existing fishing grounds can often be very contentious," said Stephen Box, senior author on the study and lead marine biologist of the Marine Conservation Program at the Smithsonian Marine Station in Fort Pierce, Fla., a marine biodiversity and ecosystem research center of the Smithsonian's National Museum of Natural History. "Fishers may oppose plans they see as taking away a large proportion of their fishing area, which could threaten their income without clear benefits being apparent. Our design approach resolves this point of tension showing that it is possible to design reserve networks that provide measurable benefits to fishers, improving catches while sustaining the target population. This really is important as it can help align fisheries stakeholders and conservation practitioners behind a joint plan, removing a key obstacle to reaching sustainable conservation successes with economically important marine species." Fully protected marine reserves are an important tool for managing the ocean's resources. By protecting the plants and animals that live within them, reserves protect a portion of exploited populations to recover and persist for future generations. But increasingly, researchers and conservationists are recognizing that for these reserves to succeed, they must balance their long-term conservation goals with the more immediate needs of local communities. Economic and sustainability objectives are often seen as being in conflict with one another, but according to the authors of the new study, both can and should be considered during the initial planning of a new reserve network and can be balanced effectively. "We want to protect [the ocean's resources] so they will be available in the future, but we also want to let people keep using them," said Iliana Chollett, the lead author of the study and a postdoctoral fellow in the Marine Conservation Program and at the University of California, Davis. Designing a reserve that will benefit local fisheries requires deep knowledge of the ecosystem and the species the reserve is designed to protect. With reliable data about animal behavior and ocean currents, computer models can calculate how a reserve will affect the abundance of a particular species in fishing areas outside its boundaries, as well as the reserve's impact on long-term sustainability. Such models have been used to assess existing or proposed reserves, but because they require massive amounts of data and intense computer processing, they have been considered impractical for use in the design phase to identify the best locations to place a new reserve network. Chollett, whose research aims to find alternatives to dangerous and unsustainable fishing practices that are currently used in Latin America and the Caribbean, knew it would take a lot of time and effort to use this approach to design a new reserve--but she believed it could be done. She and her colleagues set out to design a network of reserves to restore and preserve populations of spiny lobsters in the waters off the northeastern coast of Honduras. The spiny lobster is the most economically valuable marine resource in the Caribbean and a key component of the commercial fishery in Honduras, but its numbers are believed to be threatened due to overfishing. Researchers from the Smithsonian Marine Station, Florida Atlantic University, the Florida Fish and Wildlife Conservation Commission, the University of California, Davis and the University of Queensland worked together to collect and analyze the relevant biological and oceanographic data. Their analysis incorporated marine biologists' findings about how spiny lobsters grow, reproduce and die and how adult lobsters move across the ocean floor. Data about ocean currents, which can carry and distribute tiny lobster larvae far from the places where they hatch, and habitat maps of the seafloor were also essential. The team used these data to determine where in the ocean lobster populations would increase if particular patches were protected by reserves and how these areas would seed and spill over into fished areas. They ran the model repeatedly, using the Smithsonian's high-performance computer to predict the effect of numerous reserve networks in order to optimize the design. They found that by protecting 20 percent of the fishing grounds, they could ensure the long-term survival of the lobster population while also increasing the numbers of lobsters expected to inhabit local fishing areas available to the local fishers. A crucial finding was that the network enabled a sustainable fishery only if current levels of fishing effort remain stable into the future. Chollett says the reserve network that the team has designed could be an important component in a larger effort to introduce models and strategies to improve Honduran fishing practices and make them more sustainable. She also hopes the approach will be broadly applied to the design of marine reserves around the world.


A team led by scientists from the Smithsonian's Marine Conservation Program report in the journal Conservation Letters Nov. 17 that they have designed a model network of marine reserves off the Caribbean coast of Honduras, which can support the long-term preservation of spiny lobsters within the country's waters while also increasing fishing yields of the species in fishing areas outside the reserves' borders. "Placing marine reserves across existing fishing grounds can often be very contentious," said Stephen Box, senior author on the study and lead marine biologist of the Marine Conservation Program at the Smithsonian Marine Station in Fort Pierce, Fla., a marine biodiversity and ecosystem research center of the Smithsonian's National Museum of Natural History. "Fishers may oppose plans they see as taking away a large proportion of their fishing area, which could threaten their income without clear benefits being apparent. Our design approach resolves this point of tension showing that it is possible to design reserve networks that provide measurable benefits to fishers, improving catches while sustaining the target population. This really is important as it can help align fisheries stakeholders and conservation practitioners behind a joint plan, removing a key obstacle to reaching sustainable conservation successes with economically important marine species." Fully protected marine reserves are an important tool for managing the ocean's resources. By protecting the plants and animals that live within them, reserves protect a portion of exploited populations to recover and persist for future generations. But increasingly, researchers and conservationists are recognizing that for these reserves to succeed, they must balance their long-term conservation goals with the more immediate needs of local communities. Economic and sustainability objectives are often seen as being in conflict with one another, but according to the authors of the new study, both can and should be considered during the initial planning of a new reserve network and can be balanced effectively. "We want to protect [the ocean's resources] so they will be available in the future, but we also want to let people keep using them," said Iliana Chollett, the lead author of the study and a postdoctoral fellow in the Marine Conservation Program and at the University of California, Davis. Designing a reserve that will benefit local fisheries requires deep knowledge of the ecosystem and the species the reserve is designed to protect. With reliable data about animal behavior and ocean currents, computer models can calculate how a reserve will affect the abundance of a particular species in fishing areas outside its boundaries, as well as the reserve's impact on long-term sustainability. Such models have been used to assess existing or proposed reserves, but because they require massive amounts of data and intense computer processing, they have been considered impractical for use in the design phase to identify the best locations to place a new reserve network. Chollett, whose research aims to find alternatives to dangerous and unsustainable fishing practices that are currently used in Latin America and the Caribbean, knew it would take a lot of time and effort to use this approach to design a new reserve—but she believed it could be done. She and her colleagues set out to design a network of reserves to restore and preserve populations of spiny lobsters in the waters off the northeastern coast of Honduras. The spiny lobster is the most economically valuable marine resource in the Caribbean and a key component of the commercial fishery in Honduras, but its numbers are believed to be threatened due to overfishing. Researchers from the Smithsonian Marine Station, Florida Atlantic University, the Florida Fish and Wildlife Conservation Commission, the University of California, Davis and the University of Queensland worked together to collect and analyze the relevant biological and oceanographic data. Their analysis incorporated marine biologists' findings about how spiny lobsters grow, reproduce and die and how adult lobsters move across the ocean floor. Data about ocean currents, which can carry and distribute tiny lobster larvae far from the places where they hatch, and habitat maps of the seafloor were also essential. The team used these data to determine where in the ocean lobster populations would increase if particular patches were protected by reserves and how these areas would seed and spill over into fished areas. They ran the model repeatedly, using the Smithsonian's high-performance computer to predict the effect of numerous reserve networks in order to optimize the design. They found that by protecting 20 percent of the fishing grounds, they could ensure the long-term survival of the lobster population while also increasing the numbers of lobsters expected to inhabit local fishing areas available to the local fishers. A crucial finding was that the network enabled a sustainable fishery only if current levels of fishing effort remain stable into the future. Chollett says the reserve network that the team has designed could be an important component in a larger effort to introduce models and strategies to improve Honduran fishing practices and make them more sustainable. She also hopes the approach will be broadly applied to the design of marine reserves around the world. Explore further: AP Analysis: How well will Antarctic marine reserve work? More information: Iliana Chollett et al, A Genuine Win-Win: Resolving the "Conserve or Catch" Conflict in Marine Reserve Network Design, Conservation Letters (2016). DOI: 10.1111/conl.12318


Wang R.,University of Florida | Paul V.J.,Smithsonian Marine Station | Luesch H.,University of Florida
Free Radical Biology and Medicine | Year: 2013

Increased amounts of reactive oxygen species (ROS) have been implicated in many pathological conditions, including cancer. The major machinery that the cell employs to neutralize excess ROS is through the activation of the antioxidant-response element (ARE) that controls the activation of many phase II detoxification enzymes. The transcription factor that recognizes the ARE, Nrf2, can be activated by a variety of small molecules, most of which contain an α,β-unsaturated carbonyl system. In the pursuit of chemopreventive agents from marine organisms, we built, fractionated, and screened a library of 30 field-collected eukaryotic algae from Florida. An edible green alga, Ulva lactuca, yielded multiple active fractions by ARE-luciferase reporter assay. We isolated three monounsaturated fatty acid (MUFA) derivatives as active components, including a new keto-type C18 fatty acid (1), the corresponding shorter chain C16 acid (2), and an amide derivative (3) of the C18 acid. Their chemical structures were elucidated by NMR and mass spectrometry. All three contain the conjugated enone motif between C7 and C9, which is thought to be responsible for the ARE activity. Subsequent biological studies focused on 1, the most active and abundant ARE activator isolated. C18 acid 1 induced the expression of ARE-regulated cytoprotective genes, including NAD(P)H:quinone oxidoreductase 1, heme oxygenase 1, thioredoxin reductase 1, both subunits of the glutamate-cysteine ligase (catalytic subunit and modifier subunit), and the cystine/glutamate exchange transporter, in IMR-32 human neuroblastoma cells. Its cellular activity requires the presence of Nrf2 and PI3K function, based on RNA interference and pharmacological inhibitor studies, respectively. Treatment with 1 led only to Nrf2 activation, and not the increase in production of NRF2 mRNA. To test its ARE activity and cytoprotective potential in vivo, we treated mice with a single dose of a U. lactuca fraction that was enriched with 1, which showed ARE-activating effects similar to those observed in vitro. This could be owing to this fraction's ability to stabilize Nrf2 through inhibition of Keap1-mediated Nrf2 ubiquitination and the subsequent accumulation and nuclear translocation of Nrf2. The induction of many ARE-driven antioxidant genes in vivo and most prominently in the heart agreed with the commonly recognized cardioprotective properties of MUFAs. A significant increase in Nqo1 transcript levels was also found in other mouse tissues such as the brain, lung, and stomach. Collectively, this study provides new insight into why consumption of dietary seaweed may have health benefits, and the identified compounds add to the list of chemopreventive dietary unsaturated fatty acids. © 2013 Elsevier Inc.


News Article | January 4, 2016
Site: www.sciencenews.org

One whale spotted in the wrong ocean seemed merely odd. But a second misplaced whale looked more like a sign of an ecological shake-up: Pacific Ocean fauna moving into the Atlantic Ocean and vice versa. As the Arctic’s icy barriers melt, new waterways may soon allow many formerly separated animals to move and mix. “We do believe we’re seeing a faunal exchange,” says Seabird McKeon of the Smithsonian Marine Station in Fort Pierce, Fla. Species moving from one ocean might disrupt life in the other — competing with some longtime residents, preying on others — or maybe change hardly anything. “We just do not know what’s going to happen,” McKeon says. He and seven other scientists compiled from various sources several years’ worth of wrong-ocean sightings of whales and birds suspected to have crossed the Arctic or mingled with counterparts from the opposite ocean. The compilation, published online November 30 in Global Change Biology, isn’t big. But for long-lived creatures such as whales and some seabirds, a trickle of animals could establish a new population. Unusual sightings of birds and mammals (a selection below) suggest that once-blocked populations of animals might already be moving now that enough Arctic ice is melting to allow it.  Expansion of an Arctic population into Hudson Bay as ice blockades melt allows the whales to prey on beluga whales, narwhals and at least four seal species. An Atlantic subspecies was spotted in California in 2011; Pacific subspecies were found in Newfoundland and Norway in 2014. The Northern Pacific seabird was seen in England in 2009. The North Atlantic seabird may now be breeding in the Pacific. “Even if the strays are few, even if it’s a very slow process, there is a chance of establishment,” McKeon says. “That’s why we’re excited for people to really start watching this process.” Birders, whale watchers and other citizen scientists offer the best hope for catching early signs of any species moving across the Arctic. “If an individual bird ends up in an alternative ocean basin, that is not something that is likely to be picked up by standard scientific programs,” McKeon says. In the past, thick permanent sea ice in the Arctic plus potentially lethal water temperatures, scarce food, unusual salinity and other menaces have acted as a barrier between oceans, largely blocking animal journeys for the last 3 million years. But climate change is opening up a path. The 10 skimpiest minimums for summertime ice observed since the satellite era began have all occurred in the last 11 years, NASA analyses show. Summer ice has dwindled enough on occasion, such as in 2012, to raise commercial hopes of workable waterway passages for shipping. Feasible paths are opening in successive years through the archipelago of islands in eastern Canada, and other routes may form, too, so trade ships in coming decades may be able to shortcut through the summertime Arctic. Human commerce and the politics of climate change get more widespread attention than the chance that animals will venture along the new routes. But rearranging species’ ranges could have sweeping consequences, too. A notorious example of the unintended troubles that range changes can cause comes from the Suez Canal in Egypt. The canal “has been singularly successful as an invasion corridor,” says Bella Galil of the National Institute of Oceanography in Haifa, Israel. Of nearly 700 alien species now found in the Mediterranean Sea, half have arrived through the canal since it opened in 1869, Galil reported in the April Biological Invasions. In summer, swarms of nomad jellyfish (Rhopilema nomadica), originally from the Red Sea, clog fishing nets and block intake pipes at desalinization and power plants in Israel. Another newcomer, the poisonous Lagocephalus sceleratus puffer fish, puts several people in the hospital each year. And introductions such as the goldband goatfish and a kind of spiny oyster have wiped out their native counterparts. In contrast, the Panama Canal shepherds traffic through locks filled with freshwater, which reduces the risk of saltwater Pacific species sloshing through to the Caribbean Sea and vice versa. And thank goodness. McKeon says he has heard discussions about whether a saltwater canal in Panama would have let the venomous sea snakes from the Pacific wriggle their way into the Caribbean. In the rapidly changing Arctic, at least one Pacific species has already established populations on the North Atlantic side for the first time in about 800,000 years. Microscopic strings of silica-encased Neodenticula seminae diatoms turned up in the late 1990s in the Labrador Sea, an international research team reported in 2007. The researchers argue against the notion that the diatoms merely hitchhiked in some ship’s ballast water. Instead, the diatoms’ presence could be a sign that ocean circulation patterns are changing in the Arctic, swirling water and its living residents across the pole. What the diatoms will do Atlanticside isn’t clear, but they have now spread to northern Nordic waters, a paper published in 2013 reports, where there’s no sign they have ever been before. Of perhaps more popular interest than transplanted diatoms are potentially Arctic-crossing whales. Gray whales persist in the Pacific but went extinct in the Atlantic more than two centuries ago. In 2010, a marine-mammal monitoring program photographed a gray whale off the coast of Israel. “It was really a huge surprise to everybody,” says Elizabeth Alter of York College CUNY in Jamaica, N.Y., a coauthor with McKeon on the new paper. “There was discussion at first of whether the photos might have been photoshopped.” (They were not, it turned out.) In 2013, a monitoring group sighted another gray whale along the coast of Namibia. It seems improbable that gray whales from the northern Pacific had looped down to the Southern Hemisphere to swim around continents and then into the Atlantic, Alter says. She suspects the whales were feeding along the Arctic coastline as they normally do, and without much ice to block their progress, inadvertently hugged the coast all the way to the Atlantic side. Should gray whales eventually re­colonize the Atlantic, McKeon expects that their new neighbors would notice. Unlike similar whales with baleen plates in their mouths, grays gulp whale-sized mouthfuls of soft sea-bottom gunk to savor its hidden crustaceans. In the course of dining, the whales stir up sediment, scattering clouds of invertebrates that other species eat and leaving behind whale-gouges as habitat. It’s impossible to know the impacts, but McKeon speculates on what could happen to the blue crabs that bury themselves in the mud at the mouth of the Chesapeake Bay in winter: “I can’t imagine anything much better as a snack for a wintering gray whale than sleepy blue crabs.” Melting may also bring new opportunities to another whale species, the bowheads, which live in the Arctic full time. “They can break ice that’s 2 feet thick with their heads,” Alter says. The Atlantic and Pacific bowhead populations have shared genes over the last several thousand years, Alter’s DNA studies show. And in 2010, biologists tracking both populations by satellite found a whale from each population feeding near each other. After about a week, the whales retreated in opposite directions, but left clear evidence that the melting Arctic permits populations from separate oceans to mix. Also on McKeon’s list of possible vanguards of Arctic crossovers is a northern gannet, a plunge-diving, fish-eating seabird that soars over the Atlantic with a wingspan of about 2 meters. “What every gull dreams of being,” he says. In 2011, one of these gannets showed up off the coast of Alaska. Possibly the same bird reached the Farallon Islands along northern California. The most plausible explanation, McKeon says, is that the bird had worked its way through some avian northwest passage with open water for fishing along its flight path. Open water in the Arctic could also move animals indirectly. As summer sea ice shrinks more and more, shipping could boom along Arctic routes. These ships take on ballast water in one place and release the ballast in another, letting animals (smaller than whales) catch a lift, says Jacqueline Grebmeier of the University of Maryland Center for Environmental Science. The prevailing wisdom has been that stowaways wouldn’t survive the harsh Arctic, but as the Arctic climate changes, Grebmeier can imagine circumstances now in which ballast creatures might. Whales and charismatic seabirds may be easier to spot when they switch oceans, but ballast stowaways may turn out to be more common. And as important.


Rawlinson K.A.,Smithsonian Marine Station | Rawlinson K.A.,University College London
Frontiers in Zoology | Year: 2010

Background: Planktonic life history stages of spiralians share some muscular, nervous and ciliary system characters in common. The distribution of these characters is patchy and can be interpreted either as the result of convergent evolution, or as the retention of primitive spiralian larval features. To understand the evolution of these characters adequate taxon sampling across the Spiralia is necessary. Polyclad flatworms are the only free-living Platyhelminthes that exhibit a continuum of developmental modes, with direct development at one extreme, and indirect development via a trochophore-like larval stage at the other. Here I present embryological and larval anatomical data from the indirect developing polyclad Maritrigrella crozieri, and consider these data within a comparative spiralian context.Results: After 196 h hours of embryonic development, M. crozieri hatches as a swimming, planktotrophic larva. Larval myoanatomy consists of an orthogonal grid of circular and longitudinal body wall muscles plus parenchymal muscles. Diagonal body wall muscles develop over the planktonic period. Larval neuroanatomy consists of an apical plate, neuropile, paired nerve cords, a peri-oral nerve ring, a medial nerve, a ciliary band nerve net and putative ciliary photoreceptors. Apical neural elements develop first followed by posterior perikarya and later pharyngeal neural elements. The ciliated larva is encircled by a continuous, pre-oral band of longer cilia, which follows the distal margins of the lobes; it also possesses distinct apical and caudal cilia.Conclusions: Within polyclads heterochronic shifts in the development of diagonal bodywall and pharyngeal muscles are correlated with life history strategies and feeding requirements. In contrast to many spiralians, M. crozieri hatch with well developed nervous and muscular systems. Comparisons of the ciliary bands and apical organs amongst spiralian planktonic life-stages reveal differences; M. crozieri lack a distinct ciliary band muscle and flask-shaped epidermal serotonergic cells of the apical organ. Based on current phylogenies, the distribution of ciliary bands and apical organs between polyclads and other spiralians is not congruent with a hypothesis of homology. However, some similarities exist, and this study sets an anatomical framework from which to investigate cellular and molecular mechanisms that will help to distinguish between parallelism, convergence and homology of these features. © 2010 Rawlinson; licensee BioMed Central Ltd.


McKeon C.S.,Smithsonian Marine Station | Summers K.,East Carolina University
Evolutionary Ecology | Year: 2013

Life history trade-offs in reproductive strategy are often invoked as ecological agents of evolutionary change, despite a limited amount of experimental data from the field. The larval deposition strategy of Allobates femoralis was tested in Southeastern Peru using a blocked, fully crossed experimental design. Arrays of four pools were used to test the effects of pool size and the presence of a predatory insect (Belostomatid) on the deposition behavior of A. femoralis. Further experiments investigated the colonization of insect predators into potential larval habitats and interactions between predatory insects. Results suggest that pool size, the presence of predatory aquatic insects, and interactions between predators, influence larval deposition in A. femoralis. Similar ecological interactions may have driven toxic dendrobatids to the use of arboreal phytotelmata and associated derived reproductive strategies. © 2013 Springer Science+Business Media Dordrecht.


Sharp K.H.,Smithsonian Marine Station | Distel D.,Ocean Genome Legacy | Paul V.J.,Smithsonian Marine Station
ISME Journal | Year: 2012

In this study, we examine microbial communities of early developmental stages of the coral Porites astreoides by sequence analysis of cloned 16S rRNA genes, terminal restriction fragment length polymorphism (TRFLP), and fluorescence in situ hybridization (FISH) imaging. Bacteria are associated with the ectoderm layer in newly released planula larvae, in 4-day-old planulae, and on the newly forming mesenteries surrounding developing septa in juvenile polyps after settlement. Roseobacter clade-associated (RCA) bacteria and Marinobacter sp. are consistently detected in specimens of P. astreoides spanning three early developmental stages, two locations in the Caribbean and 3 years of collection. Multi-response permutation procedures analysis on the TRFLP results do not support significant variation in the bacterial communities associated with P. astreoides larvae across collection location, collection year or developmental stage. The results are the first evidence of vertical transmission (from parent to offspring) of bacteria in corals. The results also show that at least two groups of bacterial taxa, the RCA bacteria and Marinobacter, are consistently associated with juvenile P. astreoides against a complex background of microbial associations, indicating that some components of the microbial community are long-term associates of the corals and may impact host health and survival. © 2012 International Society for Microbial Ecology All rights reserved.


Campbell J.E.,Smithsonian Marine Station | Fourqurean J.W.,Florida International University
Journal of Ecology | Year: 2014

Developing a framework for assessing interactions between multiple anthropogenic stressors remains an important goal in environmental research. In coastal ecosystems, the relative effects of aspects of global climate change (e.g. CO2 concentrations) and localized stressors (e.g. eutrophication), in combination, have received limited attention. Using a long-term (11 month) field experiment, we examine how epiphyte assemblages in a tropical seagrass meadow respond to factorial manipulations of dissolved carbon dioxide (CO2(aq)) and nutrient enrichment. In situ CO2(aq) manipulations were conducted using clear, open-top chambers, which replicated carbonate parameter forecasts for the year 2100. Nutrient enrichment consisted of monthly additions of slow-release fertilizer, nitrogen (N) and phosphorus (P), to the sediments at rates equivalent to theoretical maximum rates of anthropogenic loading within the region (1.54 g N m-2 d-1 and 0.24 g P m-2 d-1). Epiphyte community structure was assessed on a seasonal basis and revealed declines in the abundance of coralline algae, along with increases in filamentous algae under elevated CO2(aq). Surprisingly, nutrient enrichment had no effect on epiphyte community structure or overall epiphyte loading. Interactions between CO2(aq) and nutrient enrichment were not detected. Furthermore, CO2(aq)-mediated responses in the epiphyte community displayed strong seasonality, suggesting that climate change studies in variable environments should be conducted over extended time-scales. Synthesis. The observed responses indicate that for certain locations, global stressors such as ocean acidification may take precedence over local eutrophication in altering the community structure of seagrass epiphyte assemblages. Given that nutrient-driven algal overgrowth is commonly cited as a widespread cause of seagrass decline, our findings highlight that alternate climate change forces may exert proximate control over epiphyte community structure. Developing a framework for assessing interactions between multiple anthropogenic stressors remains an important goal in environmental research. In coastal ecosystems, the relative effects of global climate change (e.g. CO2 concentrations) and localized stressors (e.g. eutrophication), in combination, have received limited attention. Our in situ experiment reveals that global stressors such as ocean acidification (OA) may take precedence over local eutrophication in altering the community structure of seagrass epiphytes. Given that nutrient-driven algal overgrowth is commonly cited as a widespread cause of seagrass decline, our findings highlight that alternate climate change forces, such as OA, may exert proximate control over epiphyte community structure. © 2014 British Ecological Society.


Paerl H.W.,University of North Carolina at Chapel Hill | Paul V.J.,Smithsonian Marine Station
Water Research | Year: 2012

Cyanobacteria are the Earth's oldest (~3.5bya) oxygen evolving organisms, and they have had major impacts on shaping our modern-day biosphere. Conversely, biospheric environmental perturbations, including nutrient enrichment and climatic changes (e.g. global warming, hydrologic changes, increased frequencies and intensities of tropical cyclones, more intense and persistent droughts), strongly affect cyanobacterial growth and bloom potentials in freshwater and marine ecosystems. We examined human and climatic controls on harmful (toxic, hypoxia-generating, food web disrupting) bloom-forming cyanobacteria (CyanoHABs) along the freshwater to marine continuum. These changes may act synergistically to promote cyanobacterial dominance and persistence. This synergy is a formidable challenge to water quality, water supply and fisheries managers, because bloom potentials and controls may be altered in response to contemporaneous changes in thermal and hydrologic regimes. In inland waters, hydrologic modifications, including enhanced vertical mixing and, if water supplies permit, increased flushing (reducing residence time) will likely be needed in systems where nutrient input reductions are neither feasible nor possible. Successful control of CyanoHABs by grazers is unlikely except in specific cases. Overall, stricter nutrient management will likely be the most feasible and practical approach to long-term CyanoHAB control in a warmer, stormier and more extreme world. © 2011 Elsevier Ltd.


Borja A.,Tecnalia | Tunberg B.G.,Smithsonian Marine Station
Ecological Indicators | Year: 2011

The Indian River Lagoon (IRL) and the St. Lucie Estuary (SLE), both located in Florida, USA, are affected by a variety of anthropogenic pressures. Benthic macroinvertebrates have been monitored quarterly since February 2005, at 15 stations, in order to assess benthic health. Since the SLE and IRL are situated in a subtropical area, it is affected by two major climatic seasons, dry (winter) and wet (summer). This contribution investigates the application of the AZTI's Marine Biotic Index (AMBI) and multivariate-AMBI (M-AMBI), to assess the ecological status of these estuaries. AMBI was firstly calculated after assigning most of the previously unassigned species to each of the five ecological groups (from sensitive to first order opportunistic species). Three main benthic assemblages, associated tooligohaline, meso-polyhaline and euhaline stretches, have been identified within the area. Reference conditions of richness, Shannon's diversity and AMBI have been derived for these assemblages; M-AMBI has then been calculated. Both methods show that the inner part of the SLE is affected by anthropogenic pressures (increased freshwater inflow, with elevated nutrient input, and sedimentation), whilst the IRL is less affected. We have demonstrated that AMBI and M-AMBI are insensitive to the dramatic seasonal changes occurring in the SLE/IRL. At some of the stations a significant positive trend in benthic quality has been identified, linked to the polluted freshwater discharges decrease. The use of both tools seems adequate in assessing benthic health in this subtropical area. © 2010 Elsevier Ltd. All rights reserved.

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