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Bishop MJ, Kelaher BP. Context-specific effects of the identity of detrital mixtures on invertebrate communities. Ecol Evol 2013; 3:3986-99. [PMID: 24198954 PMCID: PMC3810889 DOI: 10.1002/ece3.775] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 08/15/2013] [Accepted: 08/16/2013] [Indexed: 11/08/2022] Open
Abstract
Many aquatic ecosystems are sustained by detrital subsidies of leaf litter derived from exogenous sources. Although numerous studies have examined the effects of litter species richness and identity on decomposition processes, it remains unclear how these effects extend to associated invertebrate communities or how these effects vary spatially according to local environmental context. Using field enrichment experiments, we assessed how the species richness, assemblage composition, and supply of detrital litter resources interact to affect benthic communities of three temperate Australian estuarine mudflats. Our experiments utilized eight litter sources that are presently experiencing human-mediated changes in their supply to estuarine mudflats. Contrary to predictions, we did not detect effects of the species richness of detrital mixtures on benthic communities. Macroinvertebrate community structure and, in particular, abundance were, instead, influenced by the assemblage composition of detrital mixtures. At two of the three sites, plots receiving the most labile detrital mix, containing the ephemeral algae Chaetomorpha and Ulva, supported the fewest macroinvertebrates of all the experimental enrichments. The large effect of detrital mix identity on macroinvertebrate communities is of concern given present trends of proliferation of macroalgae at the expense of more refractory seagrasses and marsh grasses. As such environmental degradation continues, it will be important to more fully understand under what environmental contexts such compositional changes in detrital resources will have the most detrimental effects on important prey resources for commercially important fish and wading shorebirds.
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Kelaher BP, Bishop MJ, Potts J, Scanes P, Skilbeck G. Detrital diversity influences estuarine ecosystem performance. GLOBAL CHANGE BIOLOGY 2013; 19:1909-1918. [PMID: 23505131 DOI: 10.1111/gcb.12162] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Accepted: 01/16/2013] [Indexed: 06/01/2023]
Abstract
Global losses of seagrasses and mangroves, eutrophication-driven increases in ephemeral algae, and macrophyte invasions have impacted estuarine detrital resources. To understand the implications of these changes on benthic ecosystem processes, we tested the hypotheses that detrital source richness, mix identity, and biomass influence benthic primary production, metabolism, and nutrient fluxes. On an estuarine muddy sandflat, we manipulated the availability of eight detrital sources, including mangrove, seagrass, and invasive and native algal species that have undergone substantial changes in distribution. Mixes of these detrital sources were randomly assigned to one of 12 treatments and dried detrital material was added to seventy-two 0.25 m(2) plots (n = 6 plots). The treatments included combinations of either two or four detrital sources and high (60 g) or low (40 g) levels of enrichments. After 2 months, the dark, light, and net uptake of NH4 (+) , dissolved inorganic nitrogen, and the dark efflux of dissolved organic nitrogen were each significantly influenced by the identity of detrital mixes, rather than detrital source richness or biomass. However, gross and net primary productivity, average oxygen flux, and net NOX and dissolved inorganic phosphorous fluxes were significantly greater in treatments with low than with high detrital source richness. These results demonstrate that changes in detrital source richness and mix identity may be important drivers of estuarine ecosystem performance. Continued impacts to estuarine macrophytes may, therefore, further alter detritus-fueled productivity and processes in estuaries. Specific tests that address predicted future changes to detrital resources are required to determine the consequences of this significant environmental problem.
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Keith DA, Rodríguez JP, Rodríguez-Clark KM, Nicholson E, Aapala K, Alonso A, Asmussen M, Bachman S, Basset A, Barrow EG, Benson JS, Bishop MJ, Bonifacio R, Brooks TM, Burgman MA, Comer P, Comín FA, Essl F, Faber-Langendoen D, Fairweather PG, Holdaway RJ, Jennings M, Kingsford RT, Lester RE, Mac Nally R, McCarthy MA, Moat J, Oliveira-Miranda MA, Pisanu P, Poulin B, Regan TJ, Riecken U, Spalding MD, Zambrano-Martínez S. Scientific foundations for an IUCN Red List of ecosystems. PLoS One 2013; 8:e62111. [PMID: 23667454 PMCID: PMC3648534 DOI: 10.1371/journal.pone.0062111] [Citation(s) in RCA: 146] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Accepted: 03/16/2013] [Indexed: 11/17/2022] Open
Abstract
An understanding of risks to biodiversity is needed for planning action to slow current rates of decline and secure ecosystem services for future human use. Although the IUCN Red List criteria provide an effective assessment protocol for species, a standard global assessment of risks to higher levels of biodiversity is currently limited. In 2008, IUCN initiated development of risk assessment criteria to support a global Red List of ecosystems. We present a new conceptual model for ecosystem risk assessment founded on a synthesis of relevant ecological theories. To support the model, we review key elements of ecosystem definition and introduce the concept of ecosystem collapse, an analogue of species extinction. The model identifies four distributional and functional symptoms of ecosystem risk as a basis for assessment criteria: A) rates of decline in ecosystem distribution; B) restricted distributions with continuing declines or threats; C) rates of environmental (abiotic) degradation; and D) rates of disruption to biotic processes. A fifth criterion, E) quantitative estimates of the risk of ecosystem collapse, enables integrated assessment of multiple processes and provides a conceptual anchor for the other criteria. We present the theoretical rationale for the construction and interpretation of each criterion. The assessment protocol and threat categories mirror those of the IUCN Red List of species. A trial of the protocol on terrestrial, subterranean, freshwater and marine ecosystems from around the world shows that its concepts are workable and its outcomes are robust, that required data are available, and that results are consistent with assessments carried out by local experts and authorities. The new protocol provides a consistent, practical and theoretically grounded framework for establishing a systematic Red List of the world's ecosystems. This will complement the Red List of species and strengthen global capacity to report on and monitor the status of biodiversity.
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Cooke BC, Jones AR, Goodwin ID, Bishop MJ. Nourishment practices on Australian sandy beaches: a review. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2012; 113:319-327. [PMID: 23103149 DOI: 10.1016/j.jenvman.2012.09.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Revised: 09/16/2012] [Accepted: 09/27/2012] [Indexed: 06/01/2023]
Abstract
It is predicted that the coastal zone will be among the environments worst affected by projected climate change. Projected losses in beach area will negatively impact on coastal infrastructure and continued recreational use of beaches. Beach nourishment practices such as artificial nourishment, replenishment and scraping are increasingly used to combat beach erosion but the extent and scale of projects is poorly documented in large areas of the world. Through a survey of beach managers of Local Government Areas and a comprehensive search of peer reviewed and grey literature, we assessed the extent of nourishment practices in Australia. The study identified 130 beaches in Australia that were subject to nourishment practices between 2001 and 2011. Compared to projects elsewhere, most Australian projects were small in scale but frequent. Exceptions were nine bypass projects which utilised large volumes of sediment. Most artificial nourishment, replenishment and beach scraping occurred in highly urbanised areas and were most frequently initiated in spring during periods favourable to accretion and outside of the summer season of peak beach use. Projects were generally a response to extreme weather events, and utilised sand from the same coastal compartment as the site of erosion. Management was planned on a regional scale by Local Government Authorities, with little monitoring of efficacy or biological impact. As rising sea levels and growing coastal populations continue to put pressure on beaches a more integrated approach to management is required, that documents the extent of projects in a central repository, and mandates physical and biological monitoring to help ensure the engineering is sustainable and effective at meeting goals.
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Bishop MJ, Kelaher BP. Replacement of native seagrass with invasive algal detritus: impacts to estuarine sediment communities. Biol Invasions 2012. [DOI: 10.1007/s10530-012-0267-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Bishop MJ, Byers JE, Marcek BJ, Gribben PE. Density-dependent facilitation cascades determine epifaunal community structure in temperate Australian mangroves. Ecology 2012; 93:1388-401. [PMID: 22834379 DOI: 10.1890/10-2296.1] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
Co-occurring foundation species can determine biological community structure via facilitation cascades. We examined the density dependencies of facilitation cascades, including how the density of a basal foundation species influences the density of secondary foundation species, and how the density of secondary foundation species influences community structure. The system in which we assessed density dependencies was a temperate mangrove forest in which pneumatophores trap the fucoid alga Hormosira banksii and provide substrate for the oyster, Saccostrea glomerata. The alga and oyster in turn determine benthic community structure. In the field, algal biomass was positively correlated with pneumatophore density. Oysters, by contrast, were highly over-dispersed and correlated with the presence/absence of pneumatophores. Epifaunal abundance and species richness were positively correlated with algal and oyster abundance, but their effects were independent. The positive effect of pneumatophore density on epifauna was primarily an indirect effect of trapping more algae. Pneumatophores did not directly influence invertebrate communities. Experiments revealed that, at very low pneumatophore densities, algal retention was insufficient to facilitate epifauna above that found on pneumatophores alone. At higher densities, however, increasing the density of pneumatophores increased algal retention, and the density and diversity of associated invertebrates. Shading by the mangrove canopy reduced algal biomass but did not modify the density-dependent nature of the cascade. Our results extend facilitation theory by showing that the density of both basal and secondary foundation species can be critical in triggering facilitation cascades. Our study also reveals that, where foundation species co-occur, multiple, independent cascades may arise from a single basal facilitator. These findings enhance our understanding of the role of density-dependent facilitation cascades in community assembly.
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Bishop MJ, Hutchings PA. How useful are port surveys focused on target pest identification for exotic species management? MARINE POLLUTION BULLETIN 2011; 62:36-42. [PMID: 20934194 DOI: 10.1016/j.marpolbul.2010.09.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2010] [Revised: 09/09/2010] [Accepted: 09/09/2010] [Indexed: 05/30/2023]
Abstract
Monitoring surveys are an important tool for detecting new arrivals of exotic species, for documenting patterns of invasion, and exotic species impacts. Faced with time and cost constraints, these surveys are increasingly focused on lists of target pest species, identified as being most likely to arrive and cause significant harm. We used the national survey of Australian international ports for introduced marine pests as a case study to assess: (1) the taxonomic rigor of surveys focused on detection of target species; and (2) how the ability of port surveys to inform invasion patterns is dependent on taxonomic approach. Our analysis of the 46 available reports revealed common sub-optimal taxonomic practices that compromised their utility to identify abiotic conditions that are good predictors of biological invasion. Thus, although surveys for target species may provide information on the distribution of a handful of species, they may fail to do much else.
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Wilkie EM, Roach AC, Micevska T, Kelaher BP, Bishop MJ. Effects of a chelating resin on metal bioavailability and toxicity to estuarine invertebrates: divergent results of field and laboratory tests. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2010; 158:1261-1269. [PMID: 20193975 DOI: 10.1016/j.envpol.2010.01.027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2009] [Revised: 01/27/2010] [Accepted: 01/28/2010] [Indexed: 05/28/2023]
Abstract
Benthic invertebrates can uptake metals through diffusion of free ion solutes, or ingestion of sediment-bound forms. This study investigated the efficacy of the metal chelating resin SIR 300 in adsorbing porewater metals and isolating pathways of metal exposure. A field experiment (Botany Bay, Sydney, Australia) and a laboratory toxicity test each manipulated the availability of porewater metals within contaminated and uncontaminated sediments. It was predicted that within contaminated sediments, the resin would adsorb porewater metals and reduce toxicity to invertebrates, but in uncontaminated sediments, the resin would not significantly affect these variables. Whereas in the laboratory, the resin produced the predicted results, in the field the resin increased porewater metal concentrations of contaminated sediments for at least 34 days and decreased abundances of four macroinvertebrate groups, and richness in all sediments. These contrasting findings highlight the limits of extrapolating the results of laboratory experiments to the field environment.
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Carnegie RB, Stokes NA, Audemard C, Bishop MJ, Wilbur AE, Alphin TD, Posey MH, Peterson CH, Burreson EM. Strong seasonality of Bonamia sp. infection and induced Crassostrea ariakensis mortality in Bogue and Masonboro Sounds, North Carolina, USA. J Invertebr Pathol 2008; 98:335-43. [DOI: 10.1016/j.jip.2008.03.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2007] [Revised: 03/05/2008] [Accepted: 03/14/2008] [Indexed: 10/22/2022]
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Audemard C, Carnegie RB, Bishop MJ, Peterson CH, Burreson EM. Interacting effects of temperature and salinity on Bonamia sp. parasitism in the Asian oyster Crassostrea ariakensis. J Invertebr Pathol 2008; 98:344-50. [DOI: 10.1016/j.jip.2008.03.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2007] [Revised: 03/05/2008] [Accepted: 03/14/2008] [Indexed: 10/22/2022]
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Micheli F, Bishop MJ, Peterson CH, Rivera J. ALTERATION OF SEAGRASS SPECIES COMPOSITION AND FUNCTION OVER TWO DECADES. ECOL MONOGR 2008. [DOI: 10.1890/06-1605.1] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Bishop MJ, Kelaher BP. Non-additive, identity-dependent effects of detrital species mixing on soft-sediment communities. OIKOS 2008. [DOI: 10.1111/j.0030-1299.2008.16418.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Bishop MJ, Rodriguez B, Trayanova N, Gavaghan DJ. Modulation of shock-end virtual electrode polarisation as a direct result of 3D fluorescent photon scattering. CONFERENCE PROCEEDINGS : ... ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL CONFERENCE 2008; 2006:1556-9. [PMID: 17946049 DOI: 10.1109/iembs.2006.259243] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Due to the large transmural variation in transmembrane potential following the application of strong electric shocks, it is thought that fluorescent photon scattering from depth plays a significant role in optical signal modulation at shock-end. For the first time, a model of photon scattering is used to accurately synthesize fluorescent signals over the irregular geometry of the rabbit ventricles following the application of such strong shocks. A bidomain representation of electrical activity is combined with finite element solutions to the photon diffusion equation, simulating both the excitation and emission processes, over an anatomically-based model of rabbit ventricular geometry and fiber orientation. Photon scattering from within a 3D volume beneath the epicardial optical recording site is shown to transduce differences in transmembrane potential within this volume through the myocardial wall. This leads directly to a significantly modulated optical signal response with respect to that predicted by the bidomain simulations, distorting epicardial virtual electrode polarization produced at shock-end. Furthermore, we show that this degree of distortion is very sensitive to the optical properties of the tissue, an important variable to consider during experimental mapping set-ups. These findings provide an essential first-step in aiding the interpretation of experimental optical mapping recordings following strong defibrillation shocks.
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J. Bishop M, P. Kelaher B. Non-additive, identity-dependent effects of detrital species mixing on soft-sediment communities. OIKOS 2008. [DOI: 10.1111/j.2008.0030-1299.16418.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Krassoi FR, Brown KR, Bishop MJ, Kelaher BP, Summerhayes S. Condition-specific competition allows coexistence of competitively superior exotic oysters with native oysters. J Anim Ecol 2008; 77:5-15. [DOI: 10.1111/j.1365-2656.2007.01316.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Bishop MJ, Kelaher BP, Alquezar R, York PH, Ralph PJ, Greg Skilbeck C. Trophic cul-de-sac,Pyrazus ebeninus,limits trophic transfer through an estuarine detritus-based food web. OIKOS 2007. [DOI: 10.1111/j.2006.0030-1299.15557.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Bishop MJ, Kelaher BP, Smith MPL, York PH, Booth DJ. Ratio-dependent response of a temperate Australian estuarine system to sustained nitrogen loading. Oecologia 2006; 149:701-8. [PMID: 16845540 DOI: 10.1007/s00442-006-0481-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2005] [Accepted: 06/07/2006] [Indexed: 11/26/2022]
Abstract
Classical resource- and the less studied ratio-dependent models of predator-prey relationships provide divergent predictions as to the sustained ecological effects of bottom-up forcing. While resource-dependent models, which consider only instantaneous prey density in modelling predator responses, predict community responses that are dependent on the number of trophic levels in a system, ratio-dependent models, which consider the number of prey per consumer, predict proportional increase in each level irrespective of chain length. The two models are only subtly different for systems with two or three trophic levels but in the case of four trophic levels, predict opposite effects of enrichment on primary producers. Despite the poor discriminatory power of tests of the models in systems with two or three trophic levels, field tests in estuarine and marine systems with four trophic levels have been notably absent. Sampling of phytoplankton, macroinvertebrates, invertebrate-feeding fishes, piscivorous fishes in Kooloonbung Creek, Hastings River estuary, eastern Australia, subject to over 20 years of sewage discharge, revealed increased abundances in all four trophic levels at the disturbed location relative to control sites. Increased abundance of phytoplankton at the disturbed site was counter to the predictions of resource-dependent models, which posit a reduction in the first trophic level in response to enrichment. By contrast, the increase in abundance of this first trophic level and the proportionality of increases in abundances of each of the four trophic groups to nitrogen loading provided strong support for ratio dependency. This first evidence of ratio dependence in an estuarine system with four trophic levels not only demonstrates the applicability of ecological theory which seeks to simplify the complexity of systems, but has implications for management. Although large nutrient inputs frequently induce mortality of invertebrates and fish, we have shown that smaller inputs may in fact enhance biomass of all trophic levels.
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Carnegie RB, Burreson EM, Hine PM, Stokes NA, Audemard C, Bishop MJ, Peterson CH. Bonamia perspora n. sp. (Haplosporidia), a Parasite of the Oyster Ostreola equestris, is the First Bonamia Species Known to Produce Spores. J Eukaryot Microbiol 2006; 53:232-45. [PMID: 16872291 DOI: 10.1111/j.1550-7408.2006.00100.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Examination of the oyster Ostreola equestris as a potential reservoir host for a species of Bonamia discovered in Crassostrea ariakensis in North Carolina (NC), USA, revealed a second novel Bonamia sp. Histopathology, electron microscopy, and molecular phylogenetic analysis support the designation of a new parasite species, Bonamia perspora n. sp., which is the first Bonamia species shown to produce a typical haplosporidian spore with an orifice and hinged operculum. Spores were confirmed to be from B. perspora by fluorescent in situ hybridization. Bonamia perspora was found at Morehead City and Wilmington, NC, with an overall prevalence of 1.4% (31/2,144). Uninucleate, plasmodial, and sporogonic stages occurred almost exclusively in connective tissues; uninucleate stages (2-6 microm) were rarely observed in hemocytes. Spores were 4.3-6.4 microm in length. Ultrastructurally, uninucleate, diplokaryotic, and plasmodial stages resembled those of other spore-forming haplosporidians, but few haplosporosomes were present, and plasmodia were small. Spore ornamentation consisted of spore wall-derived, thin, flat ribbons that emerged haphazardly around the spore, and which terminated in what appeared to be four-pronged caps. Number of ribbons per spore ranged from 15 to 30, and their length ranged from 1.0 to 3.4 microm. Parsimony analysis identified B. perspora as a sister species to Bonamia ostreae.
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Bishop MJ, Peterson CH. When r-selection may not predict introduced-species proliferation: predation of a nonnative oyster. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2006; 16:718-30. [PMID: 16711058 DOI: 10.1890/1051-0761(2006)016[0718:wrmnpi]2.0.co;2] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Predicting outcomes of species introductions may be enhanced by integrating life-history theory with results of contained experiments that compare ecological responses of exotic and analogue native species to dominant features of the recipient environment. An Asian oyster under consideration for introduction to the Chesapeake Bay, USA, the rapidly growing Suminoe oyster (Crassostrea ariakensis), may not be as successful an invader as its r-selected life history suggests if the trade-off for rapid growth and maturation is lower investment in defenses against blue crab (Callinectes sapidus) predation than the native Eastern oyster (Crassostrea virginica). In laboratory trials, blue crabs simultaneously offered equal numbers of Suminoe and Eastern oysters consumed more nonnatives, irrespective of whether the crabs had previous experience with Suminoe oysters as prey. Satiated blue crabs consumed nearly three times as many Suminoe oysters as Eastern oysters of 25-mm shell height, and eight times as many of 35-mm shell height. Despite blue crabs consuming small (30 mm) Suminoe oysters at twice the rate of large (40 mm) Suminoe oysters, when 40-mm Suminoe were paired with 30-mm Eastern oysters, seven times as many of the larger (Suminoe) oysters were consumed. The greater susceptibility of C. ariakensis than C. virginica to blue crab predation appears to be based upon the biomechanics of shell strength rather than active selection of a more attractive food. Much less force was required to crush shells of Suminoe than Eastern oysters of similar shell height. Tissue transplant experiments demonstrated greater predation on oyster tissues in weaker C. ariakensis shells independent of tissue identity, and duration of handling time before rejection of C. virginica exceeded the time to crush C. ariakensis. These results, coupled with the present importance of blue crab predation in limiting recovery of native Eastern oysters, imply a role for blue crabs in inhibiting Suminoe oysters, if introduced, from attaining high adult densities required to restore a fishery, provide appreciable reef habitat, and reduce turbidity through filtration. Thus, in high-predation environments, allocation of resources to rapid growth and development rather than to predation defenses reflects a life-history trade-off that may promote early stages of invasion, yet prevent attainment of dense adult populations.
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Bishop MJ, Peterson CH. Direct effects of physical stress can be counteracted by indirect benefits: oyster growth on a tidal elevation gradient. Oecologia 2005; 147:426-33. [PMID: 16249896 DOI: 10.1007/s00442-005-0273-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2005] [Accepted: 09/15/2005] [Indexed: 11/30/2022]
Abstract
The paradigmatic gradient for intertidal marine organisms of increasing physical stress from low to high elevation has long served as the basis for using direct effects of duration of water coverage to predict many biological patterns. Accordingly, changes in potential feeding time may predict the direction and magnitude of differences between elevations in individual growth rates of sessile marine invertebrates. Oysters (triploid Crassostrea ariakensis) experimentally introduced at intertidal (MLW+0.05 m) and subtidal (MLW-0.25 m) elevations in racks provided a test of the ability to use duration of water coverage to predict changes in growth. During early-to-mid winter, a depression of 38-47% in shell growth of intertidal oysters matched the 36% reduction in available feeding time relative to subtidal oysters. In late winter as solar heating of exposed oysters increased, growth differences of 52-55% departed only slightly from the predicted 39%. In spring, however, duration of water coverage failed to predict even the correct direction of growth change with elevation as intertidal oysters grew 34% faster despite 39% less feeding time. Intense seasonal development of shell fouling by other suspension feeders like ascidians, mussels, and barnacles on subtidal (94% incidence) but not on aerially exposed intertidal (21-38% incidence) oysters may explain why duration of water cover failed to predict spring growth differences. Less intense fouling develops on intertidal oysters due to the physiological stress of aerial exposure on settlers, especially during higher temperatures and longer solar exposures of spring. Fouling by suspension feeders is known to reduce growth of the host through localized competition for food and added energetic costs. Thus, in springtime, indirect effects of aerial exposure providing a partial refuge from biological enemies overwhelmed direct effects of reduced duration of water coverage to reverse the expected pattern of slower intertidal growth of a marine invertebrate.
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Bishop MJ. Artificial sampling units: a tool for increasing the sensitivity of tests for impact in soft sediments. ENVIRONMENTAL MONITORING AND ASSESSMENT 2005; 107:203-20. [PMID: 16418913 DOI: 10.1007/s10661-005-5311-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2004] [Accepted: 08/29/2004] [Indexed: 05/06/2023]
Abstract
The distribution of benthic organisms in soft sediments is patchy in time and space on many scales. Such variability makes assessment of ecological impacts difficult. Sediment-related variables, such as grain-size and organic content, which can affect colonization by infauna, vary over similar scales. Variations in characteristics of the sediment may contribute to spatial variability in infaunal assemblages, making it difficult to detect the putative impacts of disturbances, such as the production of boat-generated waves (wash), on these organisms. Here, the hypothesis that infaunal assemblages colonizing containers of homogeneous sediment would be less spatially variable than those colonizing natural sediment was tested. Containers were deployed at mudflats differing in exposure to wash. If wash does affect colonization, a reduction in variability among sites of similar exposure should enable stronger differences to be seen between wash and no-wash zones. Assemblages colonizing homogeneous sediment were less variable than those colonizing site-specific sediment. No difference in colonization was, however, seen between places differing in their exposure to wash. Nevertheless, this method is of use in the assessment of ecological impacts in sedimentary environments, where it is difficult to detect putative impacts above the great natural variability in assemblages.
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Bishop MJ. A posteriori evaluation of strategies of management: the effectiveness of no-wash zones in minimizing the impacts of boat-wash on macrobenthic infauna. ENVIRONMENTAL MANAGEMENT 2004; 34:140-149. [PMID: 15156352 DOI: 10.1007/s00267-004-0135-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Wind-driven waves are important in structuring intertidal and shallow subtidal assemblages of macrobenthic infauna. In the sheltered waters of estuaries, boat-generated waves (wash) may play a similar role because they are typically of a similar amplitude or larger than wind-driven waves. However, few studies have attempted to determine the role of wash in structuring assemblages. Consequently, strategies for managing boating focus around minimization of bank erosion. Along the Parramatta River (Sydney, Australia), no-wash zones have been established and mangroves planted to minimize the erosion of riverbanks and collapse of seawalls purportedly caused by 35-m-long RiverCat ferries. Although intended to also reduce the ecological impacts of wash, it is unclear whether these strategies achieve this goal. Unvegetated and vegetated (among the pneumatophores of mangroves) sediments were sampled in wash and no-wash zones along the Parramatta River to assess the effectiveness of no-wash zones and vegetation of river banks in reducing the ecological impacts of wash. Specifically, it was hypothesized that (1) assemblages of intertidal macrobenthic infauna would differ between wash and no-wash zones of the Parramatta River and (2) these differences would be greater in unvegetated than in vegetated habitat. As predicted, assemblages of macrobenthic infauna differed between the wash and no-wash zones. Capitellids, nereids, and spionids were more abundant in the no-wash zone. Contrary to the hypothesis, differences were no greater in the unvegetated habitat than in the vegetated habitat. The results suggest an impact of wash on assemblages of macrobenthic infauana and a role for no-wash zones in minimizing the effects of this disturbance.
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Bishop MJ, Berman J, Bigham EC, Garrison DT, Gobel MJ, Hodson SJ, Irving PE, Liacos JA, Minick DJ, Navas F, Saussy DL, Speake JD. 2-(Anilinomethyl)imidazolines as alpha(1)-adrenoceptor agonists: the identification of alpha(1A) subtype selective 2'-carboxylic acid esters and amides. Bioorg Med Chem Lett 2001; 11:2871-4. [PMID: 11597419 DOI: 10.1016/s0960-894x(01)00569-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
2-(Anilinomethyl)imidazolines with 2'-esters or 2'-amides are potent agonists of the cloned human alpha(1)-adrenoceptors in vitro. The size and shape of the ortho substituent can have significant effects on the potency, efficacy, and subtype selectivity of these 2-(anilinomethyl)imidazolines. alpha(1A)-subtype selective agonists have been identified.
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Bishop MJ. Unintended consequences of artificial airways: replacement parts are never as good as the factory-installed. Respir Care 2001; 46:1010-1. [PMID: 11572752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
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