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1.
Sci Rep ; 11(1): 4427, 2021 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-33627747

RESUMO

Complete functional descriptions of the induction sequences of phenotypically plastic traits (perception to physiological regulation to response to outcome) should help us to clarify how plastic responses develop and operate. Ranid tadpoles express several plastic antipredator traits mediated by the stress hormone corticosterone, but how they influence outcomes remains uncertain. We investigated how predator-induced changes in the tail morphology of wood frog (Rana sylvatica) tadpoles influenced their escape performance over a sequence of time points when attacked by larval dragonflies (Anax junius). Tadpoles were raised with no predator exposure, chemical cues of dragonflies added once per day, or constant exposure to caged dragonflies crossed with no exogenous hormone added (vehicle control only), exogenous corticosterone, or metyrapone (a corticosteroid synthesis inhibitor). During predation trials, we detected no differences after four days, but after eight days, tadpoles exposed to larval dragonflies and exogenous corticosterone had developed deeper tail muscles and exhibited improved escape performance compared to controls. Treatment with metyrapone blocked the development of a deeper tail muscle and resulted in no difference in escape success. Our findings further link the predator-induced physiological stress response of ranid tadpoles to the development of an antipredator tail morphology that confers performance benefits.

2.
Sci Rep ; 10(1): 20107, 2020 11 18.
Artigo em Inglês | MEDLINE | ID: mdl-33208894

RESUMO

Our understanding of how projected climatic warming will influence the world's biota remains largely speculative, owing to the many ways in which it can directly and indirectly affect individual phenotypes. Its impact is expected to be especially severe in the tropics, where organisms have evolved in more physically stable conditions relative to temperate ecosystems. Lake Tanganyika (eastern Africa) is one ecosystem experiencing rapid warming, yet our understanding of how its diverse assemblage of endemic species will respond is incomplete. Herein, we conducted a laboratory experiment to assess how anticipated future warming would affect the mirror-elicited aggressive behaviour of Julidochromis ornatus, a common endemic cichlid in Lake Tanganyika. Given linkages that have been established between temperature and individual behaviour in fish and other animals, we hypothesized that water warming would heighten average individual aggression. Our findings support this hypothesis, suggesting the potential for water warming to mediate behavioural phenotypic expression through negative effects associated with individual health (body condition). We ultimately discuss the implications of our findings for efforts aimed at understanding how continued climate warming will affect the ecology of Lake Tanganyika fishes and other tropical ectotherms.

3.
Sci Total Environ ; 747: 141112, 2020 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-32791405

RESUMO

How anticipated climate change might affect long-term outcomes of present-day agricultural conservation practices remains a key uncertainty that could benefit water quality and biodiversity conservation planning. To explore this issue, we forecasted how the stream fish communities in the Western Lake Erie Basin (WLEB) would respond to increasing amounts of agricultural conservation practice (ACP) implementation under two IPCC future greenhouse gas emission scenarios (RCP4.5: moderate reductions; RCP8.5: business-as-usual conditions) during 2020-2065. We used output from 19 General Circulation Models to drive linked agricultural land use (APEX), watershed hydrology (SWAT), and stream fish distribution (boosted regression tree) models, subsequently analyzing how projected changes in habitat would influence fish community composition and functional trait diversity. Our models predicted both positive and negative effects of climate change and ACP implementation on WLEB stream fishes. For most species, climate and ACPs influenced species in the same direction, with climate effects outweighing those of ACP implementation. Functional trait analysis helped clarify the varied responses among species, indicating that more extreme climate change would reduce available habitat for large-bodied, cool-water species with equilibrium life-histories, many of which also are of importance to recreational fishing (e.g., northern pike, smallmouth bass). By contrast, available habitat for warm-water, benthic species with more periodic or opportunistic life-histories (e.g., northern hogsucker, greater redhorse, greenside darter) was predicted to increase. Further, ACP implementation was projected to hasten these shifts, suggesting that efforts to improve water quality could come with costs to other ecosystem services (e.g., recreational fishing opportunities). Collectively, our findings demonstrate the need to consider biological outcomes when developing strategies to mitigate water quality impairment and highlight the value of physical-biological modeling approaches to agricultural and biological conservation planning in a changing climate.


Assuntos
Ecossistema , Rios , Agricultura , Animais , Mudança Climática , Conservação dos Recursos Naturais , Hidrologia
4.
Harmful Algae ; 92: 101586, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32113601

RESUMO

With anthropogenic eutrophication and climate change causing an increase in cyanobacterial blooms worldwide, the need to understand the consequences of these blooms on aquatic ecosystems is paramount. Key questions remain unanswered with respect to how cyanobacteria blooms affect the structure of aquatic food webs, the foraging abilities of higher consumers, and the potential for cyanotoxins (e.g., microcystins [MCs]) to accumulate in fish. Toward addressing these uncertainties, physicochemical attributes, water (for MCs), phytoplankton, zooplankton, and epipelagic and benthic age-0 fish were sampled at 75 sites (44 sites for fish) of varying cyanobacteria concentration (0.1-44 µg/L) in western Lake Erie during the cyanobacteria bloom season, 2013-2014. Sites with high cyanobacteria biomass were characterized by Microcystis spp. (84-100% of biomass), detectible levels of MCs (maximum = 10.8 µg/L), and low water transparency (minimum = 0.25 m). Counter to expectations, strong positive relationships were found between cyanobacteria concentration and the biomass of several herbivorous zooplankton taxa (e.g., Daphnia, Diaphanosoma spp., Bosmina (formerly Eubosmina) coregoni, and Calanoida spp.). Expectations regarding fish were partly supported (e.g., diet selectivity varied across a cyanobacteria gradient) and partly not (e.g., consumption of zooplankton did not differ between bloom and non-bloom sites). These findings show that cyanobacterial blooms can strongly affect the distribution, composition, and interactions of zooplankton and fish, sometimes in surprising ways, highlighting the need to further explore their impact on aquatic food webs.


Assuntos
Cianobactérias , Lagos , Animais , Ecossistema , Eutrofização , Cadeia Alimentar
5.
Anim Reprod Sci ; 212: 106240, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31864496

RESUMO

This study was conducted to compare quality and quantity of sperm collected from sauger (S. canadensis) using two collection methods: stripping alone and testicular tissue collection combined with stripping. Sperm were collected from sauger broodstock (n = 20) during the breeding season. Fish were randomly assigned to two sperm collection groups: (1) stripping once or (2) stripping twice before testicular tissue collection for obtaining additional sperm. Sperm motility variables, morphology, total number produced, and fertilization (%) were compared using the two collection methods. Testicular sperm had greater total motility (70.1 ± 2.1% compared with 44.3 ± 5.7%) but there were fewer morphologically normal cells (76.4 ± 1.3% compared with 92.8 ± 1.0%) compared to sperm collected using the stripping procedure. Sperm collection regimen utilizing testicular collections and sperm extractions in combination with stripping resulted in a ∼ten fold increase in total number of motile and morphologically normal sperm (39.5 ± 4.1 × 10 9) compared with the currently utilized two sequential sperm stripping collection procedures alone (3.6 ± 4.1 × 10 9 sperm). In large-scale studies (150,000 eggs), fertilization, using sperm collected from testicular tissues (1.0 × 105 motile sperm/egg), was similar to sperm collected with only the stripping procedure (71.2 ± 5.5 %, 81.2 ± 5.5 %, P = 0.265). The results of this study indicate testicular collection combined with sperm extractions allows for collection of sperm of a quantity and quality to maximize fry production and reduce the problems with lack of broodstock availability for sperm collection.


Assuntos
Perciformes/fisiologia , Sêmen/fisiologia , Testículo/fisiologia , Animais , Masculino , Análise do Sêmen/veterinária
6.
Harmful Algae ; 77: 1-10, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-30005796

RESUMO

Mycosporine-like amino acids (MAAs) are UV-absorbing metabolites found in cyanobacteria. While their protective role from UV in Microcystis has been studied in a laboratory setting, a full understanding of the ecology of MAA-producing versus non-MAA-producing Microcystis in natural environments is lacking. This study presents a new tool for quantifying MAA-producing Microcystis and applies it to obtain insight into the dynamics of MAA-producing and non-MAA-producing Microcystis in Lake Erie. This study first developed a sensitive, specific TaqMan real-time PCR assay that targets MAA synthetase gene C (mysC) of Microcystis (quantitative range: 1.7 × 101 to 1.7 × 107 copies/assay). Using this assay, Microcystis was quantified with a MAA-producing genotype (mysC+) in water samples (n = 96) collected during March-November 2013 from 21 Lake Erie sites (undetectable - 8.4 × 106 copies/ml). The mysC+ genotype comprised 0.3-37.8% of the Microcystis population in Lake Erie during the study period. The proportion of the mysC+ genotype during high solar UV irradiation periods (mean = 18.8%) was significantly higher than that during lower UV periods (mean = 9.7%). Among the MAAs, shinorine (major) and porphyra (minor) were detected with HPLC-PDA-MS/MS from the Microcystis isolates and water samples. However, no significant difference in the MAA concentrations existed between higher and lower solar UV periods when the MAA concentrations were normalized with Microcystis mysC abundance. Collectively, this study's findings suggest that the MAA-producing Microcystis are present in Lake Erie, and they may be ecologically advantageous under high UV conditions, but not to the point that they exclusively predominate over the non-MAA-producers.


Assuntos
Toxinas Bacterianas/metabolismo , Proliferação Nociva de Algas , Lagos/microbiologia , Microcystis/metabolismo , Reação em Cadeia da Polimerase em Tempo Real/métodos , Toxinas Bacterianas/análise , Microcystis/genética , Microcystis/crescimento & desenvolvimento , Ohio , Análise Espaço-Temporal
7.
Harmful Algae ; 76: 47-57, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29887204

RESUMO

Human-driven environmental change has increased the occurrence of harmful cyanobacteria blooms in aquatic ecosystems. Concomitantly, exposure to microcystin (MC), a cyanobacterial toxin that can accumulate in animals, edible plants, and agricultural soils, has become a growing public health concern. For accurate estimation of health risks and timely monitoring, availability of reliable detection methods is imperative. Nonetheless, quantitative analysis of MCs in many types of biological and environmental samples has proven challenging because matrix interferences can hinder sample preparation and extraction procedures, leading to poor MC recovery. Herein, controlled experiments were conducted to enhance the use of ultra-performance liquid-chromatography tandem-mass spectrometry (UPLC-MS/MS) to recover MC-LR and MC-RR at a range of concentrations in seafood (fish), vegetables (lettuce), and environmental (soil) matrices. Although these experiments offer insight into detailed technical aspects of the MC homogenization and extraction process (i.e., sonication duration and centrifugation speed during homogenization; elution solvent to use during the final extraction), they centered on identifying the best (1) solvent system to use during homogenization (2-3 tested per matrix) and (2) single-phase extraction (SPE) column type (3 tested) to use for the final extraction. The best procedure consisted of the following, regardless of sample type: centrifugation speed = 4200 × g; elution volume = 8 mL; elution solvent = 80% methanol; and SPE column type = hydrophilic-lipophilic balance (HLB), with carbon also being satisfactory for fish. For sonication, 2 min, 5 min, and 10 min were optimal for fish, lettuce, and soil matrices, respectively. Using the recommended HLB column, the solvent systems that led to the highest recovery of MCs were methanol:water:butanol for fish, methanol:water for lettuce, and EDTA-Na4P2O7 for soils. Given that the recommended procedures resulted in average MC-LR and MC-RR recoveries that ranged 93 to 98%, their adoption for the preparation of samples with complex matrices before UPLC-MS/MS analysis is encouraged.


Assuntos
Monitoramento Ambiental/métodos , Contaminação de Alimentos/análise , Microcistinas/análise , Solo/química , Animais , Cromatografia Líquida de Alta Pressão , Peixes , Toxinas Marinhas , Espectrometria de Massas em Tandem , Verduras/química
8.
Food Res Int ; 102: 234-245, 2017 12.
Artigo em Inglês | MEDLINE | ID: mdl-29195944

RESUMO

Microcystin (MC), a hepatotoxin that can adversely affect human health, has become more prevalent in freshwater ecosystems worldwide, owing to an increase in toxic cyanobacteria blooms. While consumption of water and fish are well-documented exposure pathways of MCs to humans, less is known about the potential transfer to humans through consumption of vegetables that have been irrigated with MC-contaminated water. Likewise, the impact of MC on the performance of food crops is understudied. To help fill these information gaps, we conducted a controlled laboratory experiment in which we exposed lettuce, carrots, and green beans to environmentally relevant concentrations of MC-LR (0, 1, 5, and 10µg/L) via two irrigation methods (drip and spray). We used ELISA and LC-MS/MS to quantify MC-LR concentrations and in different parts of the plant (edible vs. inedible fractions), measured plant performance (e.g., size, mass, edible leaves, color), and calculated human exposure risk based on accumulation patterns. MC-LR accumulation was positively dose-dependent, with it being greater in the plants (2.2-209.2µg/kg) than in soil (0-19.4µg/kg). MC-LR accumulation varied among vegetable types, between plant parts, and between irrigation methods. MC-LR accumulation led to reduced crop growth and quality, with MC-LR persisting in the soil after harvest. Observed toxin accumulation patterns in edible fractions of plants also led to estimates of daily MC-LR intake that exceeded both the chronic reference dose (0.003µg/kg of body weight) and total daily intake guidelines (0.04µg/kg of body weight). Because the use of MC-contaminated water is common in many parts of the world, our collective findings highlight the need for guidelines concerning the use of MC-contaminated water in irrigation, as well as consumption of these crops.


Assuntos
Irrigação Agrícola , Abastecimento de Alimentos , Microcistinas/análise , Saúde Pública , Microbiologia do Solo , Verduras/microbiologia , Cromatografia Líquida , Produtos Agrícolas/microbiologia , Cianobactérias , Ensaio de Imunoadsorção Enzimática , Espectrometria de Massas em Tandem , Poluição da Água
9.
Sci Total Environ ; 569-570: 1265-1281, 2016 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-27387796

RESUMO

Complex watershed simulation models are powerful tools that can help scientists and policy-makers address challenging topics, such as land use management and water security. In the Western Lake Erie Basin (WLEB), complex hydrological models have been applied at various scales to help describe relationships between land use and water, nutrient, and sediment dynamics. This manuscript evaluated the capacity of the current Soil and Water Assessment Tool (SWAT) to predict hydrological and water quality processes within WLEB at the finest resolution watershed boundary unit (NHDPlus) along with the current conditions and conservation scenarios. The process based SWAT model was capable of the fine-scale computation and complex routing used in this project, as indicated by measured data at five gaging stations. The level of detail required for fine-scale spatial simulation made the use of both hard and soft data necessary in model calibration, alongside other model adaptations. Limitations to the model's predictive capacity were due to a paucity of data in the region at the NHDPlus scale rather than due to SWAT functionality. Results of treatment scenarios demonstrate variable effects of structural practices and nutrient management on sediment and nutrient loss dynamics. Targeting treatment to acres with critical outstanding conservation needs provides the largest return on investment in terms of nutrient loss reduction per dollar spent, relative to treating acres with lower inherent nutrient loss vulnerabilities. Importantly, this research raises considerations about use of models to guide land management decisions at very fine spatial scales. Decision makers using these results should be aware of data limitations that hinder fine-scale model interpretation.

10.
Harmful Algae ; 56: 44-66, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-28073496

RESUMO

Lake Erie supplies drinking water to more than 11 million consumers, processes millions of gallons of wastewater, provides important species habitat and supports a substantial industrial sector, with >$50 billion annual income to tourism, recreational boating, shipping, fisheries, and other industries. These and other key ecosystem services are currently threatened by an excess supply of nutrients, manifested in particular by increases in the magnitude and extent of harmful planktonic and benthic algal blooms (HABs) and hypoxia. Widespread concern for this important international waterbody has been manifested in a strong focus of scientific and public material on the subject, and commitments for Canada-US remedial actions in recent agreements among Federal, Provincial and State agencies. This review provides a retrospective synthesis of past and current nutrient inputs, impairments by planktonic and benthic HABs and hypoxia, modelling and Best Management Practices in the Lake Erie basin. The results demonstrate that phosphorus reduction is of primary importance, but the effects of climate, nitrogen and other factors should also be considered in the context of adaptive management. Actions to reduce nutrient levels by targeted Best Management Practices will likely need to be tailored for soil types, topography, and farming practices.


Assuntos
Eutrofização , Lagos/microbiologia , Anaerobiose , Animais , Canadá , Cianobactérias , Monitoramento Ambiental , Proliferação Nociva de Algas , Nitrogênio , Fósforo
11.
Nat Commun ; 6: 7724, 2015 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-26173734

RESUMO

Although climate warming is expected to benefit temperate ectotherms by lengthening the summer growing season, declines in reproductive success following short, warm winters may counter such positive effects. Here we present long-term (1973-2010) field patterns for Lake Erie yellow perch, Perca flavescens, which show that failed annual recruitment events followed short, warm winters. Subsequent laboratory experimentation and field investigations revealed how reduced reproductive success following short, warm winters underlie these observed field patterns. Following short winters, females spawn at warmer temperatures and produce smaller eggs that both hatch at lower rates and produce smaller larvae than females exposed to long winters. Our research suggests that continued climate warming can lead to unanticipated, negative effects on temperate fish populations.


Assuntos
Aquecimento Global , Lagos , Percas , Reprodução , Estações do Ano , Animais , Mudança Climática , Feminino , Peixes , Larva , Ohio , Óvulo , Dinâmica Populacional , Estados Unidos
12.
PLoS One ; 10(5): e0125234, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25954968

RESUMO

Nutrient-rich, turbid river plumes that are common to large lakes and coastal marine ecosystems have been hypothesized to benefit survival of fish during early life stages by increasing food availability and (or) reducing vulnerability to visual predators. However, evidence that river plumes truly benefit the recruitment process remains meager for both freshwater and marine fishes. Here, we use genotype assignment between juvenile and larval yellow perch (Perca flavescens) from western Lake Erie to estimate and compare recruitment to the age-0 juvenile stage for larvae residing inside the highly turbid, south-shore Maumee River plume versus those occupying the less turbid, more northerly Detroit River plume. Bayesian genotype assignment of a mixed assemblage of juvenile (age-0) yellow perch to putative larval source populations established that recruitment of larvae was higher from the turbid Maumee River plume than for the less turbid Detroit River plume during 2006 and 2007, but not in 2008. Our findings add to the growing evidence that turbid river plumes can indeed enhance survival of fish larvae to recruited life stages, and also demonstrate how novel population genetic analyses of early life stages can contribute to determining critical early life stage processes in the fish recruitment process.


Assuntos
Ecossistema , Lagos , Percas/crescimento & desenvolvimento , Percas/genética , Rios , Alelos , Animais , Genética Populacional , Genótipo , Geografia , Heterozigoto , Larva/genética , Repetições de Microssatélites/genética , Nefelometria e Turbidimetria , Movimentos da Água
13.
PLoS One ; 10(3): e0120752, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25799555

RESUMO

We provide a novel method to improve the use of natural tagging approaches for subpopulation discrimination and source-origin identification in aquatic and terrestrial animals with a passive dispersive phase. Our method integrates observed site-referenced biological information on individuals in mixed populations with a particle-tracking model to retrace likely dispersal histories prior to capture (i.e., particle backtracking). To illustrate and test our approach, we focus on western Lake Erie's yellow perch (Perca flavescens) population during 2006-2007, using microsatellite DNA and otolith microchemistry from larvae and juveniles as natural tags. Particle backtracking showed that not all larvae collected near a presumed hatching location may have originated there, owing to passive drift during the larval stage that was influenced by strong river- and wind-driven water circulation. Re-assigning larvae to their most probable hatching site (based on probabilistic dispersal trajectories from the particle backtracking model) improved the use of genetics and otolith microchemistry to discriminate among local breeding subpopulations. This enhancement, in turn, altered (and likely improved) the estimated contributions of each breeding subpopulation to the mixed population of juvenile recruits. Our findings indicate that particle backtracking can complement existing tools used to identify the origin of individuals in mixed populations, especially in flow-dominated systems.


Assuntos
Cruzamento , Percas/fisiologia , Distribuição Animal , Animais , Técnicas de Genotipagem , Hidrodinâmica , Larva/genética , Repetições de Microssatélites/genética , Percas/genética
14.
Mol Ecol ; 23(21): 5366-77, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25231387

RESUMO

Turbidity associated with river plumes is known to affect the search ability of visual predators and thus can drive 'top-down' impacts on prey populations in complex ecosystems; however, traditional quantification of predator-prey relationships (i.e. stomach content analysis) often fails with larval fish due to rapid digestion rates. Herein, we use novel molecular genetic methods to quantify larval yellow perch (YP) in predator stomachs in western Lake Erie to test the hypothesis that turbidity drives variation in larval predation. We characterize predator stomach content DNA to first identify YP DNA (single nucleotide polymorphism) and then quantify larval YP predation (microsatellite allele counting) in two river plumes differing in turbidity. Our results showed elevated larval YP predation in the less turbid river plume, consistent with a top-down impact of turbidity on larval survival. Our analyses highlight novel ecological hypothesis testing using the power of innovative molecular genetic approaches.


Assuntos
Cadeia Alimentar , Percas , Comportamento Predatório , Movimentos da Água , Animais , Bass , Conteúdo Gastrointestinal , Genótipo , Larva , Repetições de Microssatélites , Dados de Sequência Molecular , Percas/genética , Polimorfismo de Nucleotídeo Único , Rios , Análise de Sequência de DNA
15.
Nature ; 421(6926): 933-6, 2003 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-12606998

RESUMO

A central aim of ecology is to explain the heterogeneous distribution of biodiversity on earth. As expectations of diversity loss grow, this understanding is also critical for effective management and conservation. Although explanations for biodiversity patterns are still a matter for intense debate, they have often been considered to be scale-dependent. At large geographical scales, biogeographers have suggested that variation in species richness results from factors such as area, temperature, environmental stability, and geological processes, among many others. From the species pools generated by these large-scale processes, community ecologists have suggested that local-scale assembly of communities is achieved through processes such as competition, predation, recruitment, disturbances and immigration. Here we analyse hypotheses on speciation and dispersal for reef fish from the Indian and Pacific oceans and show how dispersal from a major centre of origination can simultaneously account for both large-scale gradients in species richness and the structure of local communities.


Assuntos
Antozoários , Ecossistema , Peixes/classificação , Peixes/fisiologia , Animais , Oceano Índico , Indonésia , Modelos Biológicos , Oceano Pacífico , Filipinas , Dinâmica Populacional , Especificidade da Espécie
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