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  1. Article ; Online: Prior exposure to weathered oil influences foraging of an ecologically important saltmarsh resident fish

    Ashley M. McDonald / Charles W. Martin / Guillaume Rieucau / Brian J. Roberts

    PeerJ, Vol 9, p e

    2022  Volume 12593

    Abstract: Estuarine ecosystem balance typically relies on strong food web interconnectedness dependent on a relatively low number of resident taxa, presenting a potential ecological vulnerability to extreme ecosystem disturbances. Following the Deepwater Horizon ( ... ...

    Abstract Estuarine ecosystem balance typically relies on strong food web interconnectedness dependent on a relatively low number of resident taxa, presenting a potential ecological vulnerability to extreme ecosystem disturbances. Following the Deepwater Horizon (DwH) oil spill disaster of the northern Gulf of Mexico (USA), numerous ecotoxicological studies showed severe species-level impacts of oil exposure on estuarine fish and invertebrates, yet post-spill surveys found little evidence for severe impacts to coastal populations, communities, or food webs. The acknowledgement that several confounding factors may have limited researchers’ abilities to detect negative ecosystem-level impacts following the DwH spill drives the need for direct testing of weathered oil exposure effects on estuarine residents with high trophic connectivity. Here, we describe an experiment that examined the influence of previous exposure to four weathered oil concentrations (control: 0.0 L oil m−2; low: 0.1 L oil m−2; moderate: 0.5–1 L oil m−2; high: 3.0 L oil m−2) on foraging rates of the ecologically important Gulf killifish (Fundulus grandis). Following exposure in oiled saltmarsh mesocosms, killifish were allowed to forage on grass shrimp (Palaeomonetes pugio) for up to 21 h. We found that previous exposure to the high oil treatment reduced killifish foraging rate by ~37% on average, compared with no oil control treatment. Previous exposure to the moderate oil treatment showed highly variable foraging rate responses, while low exposure treatment was similar to unexposed responses. Declining foraging rate responses to previous high weathered oil exposure suggests potential oil spill influence on energy transfer between saltmarsh and off-marsh systems. Additionally, foraging rate variability at the moderate level highlights the large degree of intraspecific variability for this sublethal response and indicates this concentration represents a potential threshold of oil exposure influence on killifish foraging. We also found that consumption of ...
    Keywords Fish behavior ; Macondo ; Nekton ; Feeding effort ; Mesocosm ; Medicine ; R ; Biology (General) ; QH301-705.5
    Subject code 590 ; 333
    Language English
    Publishing date 2022-01-01T00:00:00Z
    Publisher PeerJ Inc.
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article: Spatial distribution and morphological responses to predation in the salt marsh periwinkle

    Rietl, Anthony J / Brian J. Roberts / Madelyn G. Sorrentino

    Ecosphere. 2018 June, v. 9, no. 6

    2018  

    Abstract: The salt marsh periwinkle (Littoraria irrorata) is a common and often abundant mollusk in marshes of the Gulf and Atlantic coasts of the United States. Several studies have focused on the effects of periwinkles on Spartina alterniflora production and the ...

    Abstract The salt marsh periwinkle (Littoraria irrorata) is a common and often abundant mollusk in marshes of the Gulf and Atlantic coasts of the United States. Several studies have focused on the effects of periwinkles on Spartina alterniflora production and the effects of oil on periwinkle survivability, yet the general ecology of the snail has been underreported. In this study, we measured spatial distributions, biomass, shell repair frequency, and a suite of morphological characteristics of L. irrorata at three sites in each of five regions spanning the southeastern Louisiana Coast between the Atchafalaya and Mississippi rivers. Sampling was conducted along 50 m edge‐to‐interior transects in S. alterniflora‐dominated marshes. We found that L. irrorata density, individual biomass, and total areal biomass significantly varied by region. Each also significantly varied with distance from the marsh edge, with the exception of total periwinkle areal biomass. We saw a general trend across most regions where periwinkle density tended to be greatest 10 m from the marsh edge and biomass tended to be greatest 20–30 m from the marsh edge; however, neither periwinkle density nor biomass was related to S. alterniflora density or stem height. The allometric relationship between shell length and biomass varied significantly between all regions, indicating that this species has differing regional growth patterns. A possible driver of these regional patterns in allometry is differences in predation pressures, with increased predation scaring at Port Fourchon sites corresponding to snails with larger shells yet less internal biomass per length compared to other regions. This study provides the first large‐scale description of the spatial ecology and regional morphometry of the salt marsh periwinkle, an important organism in structuring salt marsh ecosystems, and suggests that the pressures exerted by L. irrorata on plant production found in other studies likely varies by geography and spatial location within a marsh.
    Keywords allometry ; biomass ; coasts ; ecosystems ; geography ; morphometry ; oils ; predation ; salt marshes ; snails ; Spartina alterniflora ; Louisiana
    Language English
    Dates of publication 2018-06
    Size p. e02316.
    Publishing place John Wiley & Sons, Ltd
    Document type Article
    Note JOURNAL ARTICLE
    ZDB-ID 2572257-8
    ISSN 2150-8925
    ISSN 2150-8925
    DOI 10.1002/ecs2.2316
    Database NAL-Catalogue (AGRICOLA)

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  3. Article ; Online: Can biodiversity of preexisting and created salt marshes match across scales? An assessment from microbes to predators

    Friedrich W. Keppeler / James R. Junker / Margaret J. Shaw / Scott B. Alford / Annette S. Engel / Linda M. Hooper‐Bùi / Olaf P. Jensen / Katelyn Lamb / Paola C. López‐Duarte / Charles W. Martin / Ashley M. McDonald / Jill A. Olin / Audrey T. Paterson / Michael J. Polito / Nancy N. Rabalais / Brian J. Roberts / Ryann E. Rossi / Erick M. Swenson

    Ecosphere, Vol 14, Iss 3, Pp n/a-n/a (2023)

    2023  

    Abstract: Abstract 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 ... ...

    Abstract Abstract 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 ...
    Keywords diversity ; estuary ; restoration ; salt marshes ; spatial scale ; Ecology ; QH540-549.5
    Subject code 333
    Language English
    Publishing date 2023-03-01T00:00:00Z
    Publisher Wiley
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: Stable isotope analyses identify trophic niche partitioning between sympatric terrestrial vertebrates in coastal saltmarshes with differing oiling histories

    Sydney Moyo / Hayat Bennadji / Danielle Laguaite / Anna A. Pérez-Umphrey / Allison M. Snider / Andrea Bonisoli-Alquati / Jill A. Olin / Philip C Stouffer / Sabrina S. Taylor / Paola C. López-Duarte / Brian J. Roberts / Linda Hooper-Bui / Michael J. Polito

    PeerJ, Vol 9, p e

    2021  Volume 11392

    Abstract: Bioindicator species are commonly used as proxies to help identify the ecological effects of oil spills and other stressors. However, the utility of taxa as bioindicators is dependent on understanding their trophic niche and life history characteristics, ...

    Abstract Bioindicator species are commonly used as proxies to help identify the ecological effects of oil spills and other stressors. However, the utility of taxa as bioindicators is dependent on understanding their trophic niche and life history characteristics, as these factors mediate their ecological responses. Seaside sparrows (Ammospiza maritima) and marsh rice rats (Oryzomys palustris) are two ubiquitous terrestrial vertebrates that are thought to be bioindicators of oil spills in saltmarsh ecosystems. To improve the utility of these omnivorous taxa as bioindicators, we used carbon and nitrogen stable isotope analysis to quantify their trophic niches at saltmarshes in coastal Louisiana with differing oiling histories. We found that rats generally had lower trophic positions and incorporated more aquatic prey relative to seaside sparrows. The range of resources used (i.e.,trophic niche width) varied based on oiling history. Seaside sparrows had wider trophic niches than marsh rice rats at unoiled sites, but not at oiled sites. Trophic niche widths of conspecifics were less consistent at oiled sites, although marsh rice rats at oiled sites had wider trophic niches than rats at unoiled sites. These results suggest that past oiling histories may have imparted subtle, yet differing effects on the foraging ecology of these two co-occurring species. However, the temporal lag between initial oiling and our study makes identifying the ultimate drivers of differences between oiled and unoiled sites challenging. Even so, our findings provide a baseline quantification of the trophic niches of sympatric seaside sparrows and marsh rice rats that will aid in the use of these species as indicators of oiling and other environmental stressors in saltmarsh ecosystems.
    Keywords Stable isotope analysis ; Saltmarsh ; Ammospiza maritima ; Oryzomys palustris ; Medicine ; R ; Biology (General) ; QH301-705.5
    Subject code 590
    Language English
    Publishing date 2021-07-01T00:00:00Z
    Publisher PeerJ Inc.
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article: Age validation and seasonal growth patterns of a subtropical marsh fish: The Gulf Killifish, Fundulus grandis

    Vastano, AnthonyR / Kenneth W. Able / Olaf P. Jensen / Paola C. López-Duarte / Charles W. Martin / Brian J. Roberts

    Environmental biology of fishes. 2017 Oct., v. 100, no. 10

    2017  

    Abstract: Fundulus grandis (Baird and Girard), the Gulf Killifish, is an abundant species throughout the marshes of the northern Gulf of Mexico. Its wide distribution and high site fidelity makes it an ideal indicator species for brackish and salt marshes, which ... ...

    Abstract Fundulus grandis (Baird and Girard), the Gulf Killifish, is an abundant species throughout the marshes of the northern Gulf of Mexico. Its wide distribution and high site fidelity makes it an ideal indicator species for brackish and salt marshes, which experience a variety of anthropogenic disturbances. Despite the ecological, commercial, and scientific importance of F. grandis, age determination methods have not been validated and little is known of its growth pattern. By combining a tag-recapture study with a chemical marker to stain otoliths, we validated an ageing method for F. grandis adults (49–128 mm TL) using whole sagittal otoliths and determined growth rates of recaptured individuals in winter (n = 58) and summer (n = 36) in Louisiana. Mean somatic growth in length was significantly greater during the winter (0.085 mm d⁻¹) than summer (0.054 mm d⁻¹). In contrast, mean otolith growth was significantly greater in summer (1.37 μm d⁻¹) than winter (0.826 μm d⁻¹). The uncoupling of somatic and otolith growth may be primarily attributed to warm summer temperatures, which led to enhanced otolith growth while simultaneously reducing somatic growth. Fundulus grandis was aged to a maximum of 2.25 years. The parameters of the von Bertalanffy growth model were estimated as: L ∞ = 87.27 mm, k = 2.43 year⁻¹, and t ₀ = −0.022. These findings reveal essential age and growth information for F. grandis and provide a benchmark to evaluate responses to environmental disturbances.
    Keywords Fundulus grandis ; adults ; age determination ; anthropogenic activities ; fish ; growth models ; indicator species ; otoliths ; philopatry ; salt marshes ; seasonal growth ; summer ; temperature ; winter ; Gulf of Mexico ; Louisiana
    Language English
    Dates of publication 2017-10
    Size p. 1315-1327.
    Publishing place Springer Netherlands
    Document type Article
    ZDB-ID 196790-3
    ISSN 1573-5133 ; 0378-1909
    ISSN (online) 1573-5133
    ISSN 0378-1909
    DOI 10.1007/s10641-017-0645-7
    Database NAL-Catalogue (AGRICOLA)

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  6. Article: Examining the coupling of carbon and nitrogen cycles in Appalachian streams: the role of dissolved organic nitrogen

    Lutz, Brian D / Emily S. Bernhardt / Brian J. Roberts / Patrick J. Mulholland

    Ecology. 2011 Mar., v. 92, no. 3

    2011  

    Abstract: Although regional and global models of nitrogen (N) cycling typically focus on nitrate, dissolved organic nitrogen (DON) is the dominant form of nitrogen export from many watersheds and thus the dominant form of dissolved N in many streams. Our ... ...

    Abstract Although regional and global models of nitrogen (N) cycling typically focus on nitrate, dissolved organic nitrogen (DON) is the dominant form of nitrogen export from many watersheds and thus the dominant form of dissolved N in many streams. Our understanding of the processes controlling DON export from temperate forests is poor. In pristine systems, where biological N limitation is common, N contained in recalcitrant organic matter (OM) can dominate watershed N losses. This recalcitrant OM often has moderately constrained carbon : nitrogen (C:N) molar ratios (∼25–55) and therefore, greater DON losses should be observed in sites where there is greater total dissolved organic carbon (DOC) loss. In regions where anthropogenic N pollution is high, it has been suggested that increased inorganic N availability can reduce biological demand for organic N and therefore increase watershed DON losses. This would result in a positive correlation between inorganic and organic N concentrations across sites with varying N availability. In four repeated synoptic surveys of stream water chemistry from forested watersheds along an N loading gradient in the southern Appalachians, we found surprisingly little correlation between DON and DOC concentrations. Further, we found that DON concentrations were always significantly correlated with watershed N loading and stream water [NO₃ ⁻] but that the direction of this relationship was negative in three of the four surveys. The C:N molar ratio of dissolved organic matter (DOM) in streams draining watersheds with high N deposition was very high relative to other freshwaters. This finding, together with results from bioavailability assays in which we directly manipulated C and N availabilities, suggests that heterotrophic demand for labile C can increase as a result of dissolved inorganic N (DIN) loading, and that heterotrophs can preferentially remove N‐rich molecules from DOM. These results are inconsistent with the two prevailing hypotheses that dominate interpretations of watershed DON loss. Therefore, we propose a new hypothesis, the indirect carbon control hypothesis, which recognizes that heterotrophic demand for N‐rich DOM can keep stream water DON concentrations low when N is not limiting and heterotrophic demand for labile C is high.
    Keywords bioavailability ; carbon ; dissolved organic carbon ; dissolved organic nitrogen ; forested watersheds ; heterotrophs ; hydrochemistry ; models ; nitrates ; nitrogen ; nitrogen cycle ; pollution ; streams ; surveys ; temperate forests ; Appalachian region
    Language English
    Dates of publication 2011-03
    Size p. 720-732.
    Publishing place Ecological Society of America
    Document type Article
    Note JOURNAL ARTICLE
    ZDB-ID 1797-8
    ISSN 0012-9658
    ISSN 0012-9658
    DOI 10.1890/10-0899.1
    Database NAL-Catalogue (AGRICOLA)

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    Z 4' 49/37: Show issues
    Z 7543: Show issues

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  7. Article: Key taxa in food web responses to stressors: the Deepwater Horizon oil spill

    McCann, Michael J / Brian J Roberts / Charles W Martin / F Joel Fodrie / Jessica J Johnson / Jill A Olin / Kenneth W Able / Michael J Polito / Olaf P Jensen / Paola C López‐Duarte / Robert R Christian / Shelby L Ziegler

    Frontiers in ecology and the environment. 2017 Apr., v. 15, no. 3

    2017  

    Abstract: Identifying key taxa in the response of ecosystems to perturbations relies on quantifying both their sensitivity to stressors and their importance in the overall web of interactions. If sensitive taxa occupy key network positions, then they may decrease ... ...

    Abstract Identifying key taxa in the response of ecosystems to perturbations relies on quantifying both their sensitivity to stressors and their importance in the overall web of interactions. If sensitive taxa occupy key network positions, then they may decrease the capacity of ecosystems to resist perturbations. Despite widespread concern for coastal marshes after the 2010 Deepwater Horizon oil spill in the Gulf of Mexico, impacts on individual taxa were variable, and the effects on the overall marsh food web have not been assessed. Here, we synthesize published studies on trophic relationships and oil sensitivity to identify critical taxa in the response of marsh food webs to the oil spill. Taxa such as carnivorous marsh fishes are expected to enhance resilience, while gulls, terns, and omnivorous snails may destabilize the food web. Our framework for identifying key taxa can be applied to other environmental stressors or ecosystems if both the sensitivity of individual taxa to a stressor and the food web structure are known.
    Keywords carnivores ; coasts ; ecosystems ; fish ; food webs ; Laridae ; marshes ; oil spills ; oils ; omnivores ; snails ; Gulf of Mexico
    Language English
    Dates of publication 2017-04
    Size p. 142-149.
    Publishing place John Wiley & Sons, Ltd
    Document type Article
    Note REVIEW
    ZDB-ID 2110853-5
    ISSN 1540-9309 ; 1540-9295
    ISSN (online) 1540-9309
    ISSN 1540-9295
    DOI 10.1002/fee.1474
    Database NAL-Catalogue (AGRICOLA)

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    In stock of ZB MED Bonn / Germany

    Z 7542: Show issues

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  8. Article: Examining the coupling of carbon and nitrogen cycles in Appalachian streams: the role of dissolved organic nitrogen

    Lutz, Brian D. / Emily S. Bernhardt / Brian J. Roberts / Patrick J. Mulholland

    Ecology

    Volume v. 92,, Issue no. 3

    Abstract: Although regional and global models of nitrogen (N) cycling typically focus on nitrate, dissolved organic nitrogen (DON) is the dominant form of nitrogen export from many watersheds and thus the dominant form of dissolved N in many streams. Our ... ...

    Abstract Although regional and global models of nitrogen (N) cycling typically focus on nitrate, dissolved organic nitrogen (DON) is the dominant form of nitrogen export from many watersheds and thus the dominant form of dissolved N in many streams. Our understanding of the processes controlling DON export from temperate forests is poor. In pristine systems, where biological N limitation is common, N contained in recalcitrant organic matter (OM) can dominate watershed N losses. This recalcitrant OM often has moderately constrained carbon : nitrogen (C:N) molar ratios (∼25–55) and therefore, greater DON losses should be observed in sites where there is greater total dissolved organic carbon (DOC) loss. In regions where anthropogenic N pollution is high, it has been suggested that increased inorganic N availability can reduce biological demand for organic N and therefore increase watershed DON losses. This would result in a positive correlation between inorganic and organic N concentrations across sites with varying N availability. In four repeated synoptic surveys of stream water chemistry from forested watersheds along an N loading gradient in the southern Appalachians, we found surprisingly little correlation between DON and DOC concentrations. Further, we found that DON concentrations were always significantly correlated with watershed N loading and stream water [NO₃ ⁻] but that the direction of this relationship was negative in three of the four surveys. The C:N molar ratio of dissolved organic matter (DOM) in streams draining watersheds with high N deposition was very high relative to other freshwaters. This finding, together with results from bioavailability assays in which we directly manipulated C and N availabilities, suggests that heterotrophic demand for labile C can increase as a result of dissolved inorganic N (DIN) loading, and that heterotrophs can preferentially remove N‐rich molecules from DOM. These results are inconsistent with the two prevailing hypotheses that dominate interpretations of watershed DON loss. Therefore, we propose a new hypothesis, the indirect carbon control hypothesis, which recognizes that heterotrophic demand for N‐rich DOM can keep stream water DON concentrations low when N is not limiting and heterotrophic demand for labile C is high.
    Language English
    Document type Article
    ISSN 0012-9658
    Database AGRIS - International Information System for the Agricultural Sciences and Technology

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