scholarly journals Climate Change and Species Invasion Drive Decadal Variation in Fish Fauna in the Min River, China

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1558
Author(s):  
Weide Deng ◽  
Li Lin ◽  
Xiaoxia Huang ◽  
Te-Yu Liao ◽  
Bin Kang
Keyword(s):  
Environmental Changes ◽  
Fish Fauna ◽  
Habitat Diversity ◽  
Influential Factor ◽  
Taxonomic Distinctness ◽  
Decadal Variation ◽  
Human Disturbances ◽  
Min River ◽  
Trade Offs ◽  
Ecological Protection

Freshwater fishes are threatened by increasing environmental changes and human disturbances. The Min River, the largest river in Southeastern China, contains unique fish fauna for the Oriental realm. Due to environmental changes brought by forty years of economic growth, fish numbers have dramatically declined. The average taxonomic distinctness in the 1970s was significantly higher than that in 2015, while no significant differences were found in the variation in taxonomic distinctness between the two periods. Due to the river network and habitat diversity, fish fauna composition showed significant spatial differences but lower variation than the decadal variation. Precipitation was determined to be the most influential factor in determining the spatial pattern of fish fauna, followed by temperature. Species introduced for aquaculture have invaded the endemic fish community after escape and should be reconsidered in the trade-offs between economic development and ecological protection.

Functional diversity alters the effects of a pulse perturbation on the dynamics of tritrophic food webs

2021 ◽  
Author(s):  
Ruben Ceulemans ◽  
Laurie Anne Myriam Wojcik ◽  
Ursula Gaedke
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Functional Diversity ◽  
Feedback Loop ◽  
Environmental Changes ◽  
Biodiversity Loss ◽  
Trophic Levels ◽  
Nutrient Pulse ◽  
Trade Offs ◽  
Food Web Model

Biodiversity decline causes a loss of functional diversity, which threatens ecosystems through a dangerous feedback loop: this loss may hamper ecosystems' ability to buffer environmental changes, leading to further biodiversity losses. In this context, the increasing frequency of climate and human-induced excessive loading of nutrients causes major problems in aquatic systems. Previous studies investigating how functional diversity influences the response of food webs to disturbances have mainly considered systems with at most two functionally diverse trophic levels. Here, we investigate the effects of a nutrient pulse on the resistance, resilience and elasticity of a tritrophic---and thus more realistic---plankton food web model depending on its functional diversity. We compare a non-adaptive food chain with no diversity to a highly diverse food web with three adaptive trophic levels. The species fitness differences are balanced through trade-offs between defense/growth rate for prey and selectivity/half-saturation constant for predators. We showed that the resistance, resilience and elasticity of tritrophic food webs decreased with larger perturbation sizes and depended on the state of the system when the perturbation occured. Importantly, we found that a more diverse food web was generally more resistant, resilient, and elastic. Particularly, functional diversity dampened the probability of a regime shift towards a non-desirable alternative state. In addition, despite the complex influence of the shape and type of the dynamical attractors, the basal-intermediate interaction determined the robustness against a nutrient pulse. This relationship was strongly influenced by the diversity present and the third trophic level. Overall, using a food web model of realistic complexity, this study confirms the destructive potential of the positive feedback loop between biodiversity loss and robustness, by uncovering mechanisms leading to a decrease in resistance, resilience and elasticity as functional diversity declines.

scholarly journals Memories of Migrations Past: Sociality and Cognition in Dynamic, Seasonal Environments

2021 ◽  
Vol 9 ◽  
Author(s):  
Eliezer Gurarie ◽  
Sriya Potluri ◽  
George Christopher Cosner ◽  
Robert Stephen Cantrell ◽  
William F. Fagan
Keyword(s):  
Environmental Changes ◽  
Animal Movement ◽  
Spatial Scales ◽  
Rapid Change ◽  
Reference Memory ◽  
Migratory Behavior ◽  
Migration Behavior ◽  
Long Distance ◽  
Trade Offs ◽  
Resource Dynamics

Seasonal migrations are a widespread and broadly successful strategy for animals to exploit periodic and localized resources over large spatial scales. It remains an open and largely case-specific question whether long-distance migrations are resilient to environmental disruptions. High levels of mobility suggest an ability to shift ranges that can confer resilience. On the other hand, a conservative, hard-wired commitment to a risky behavior can be costly if conditions change. Mechanisms that contribute to migration include identification and responsiveness to resources, sociality, and cognitive processes such as spatial memory and learning. Our goal was to explore the extent to which these factors interact not only to maintain a migratory behavior but also to provide resilience against environmental changes. We develop a diffusion-advection model of animal movement in which an endogenous migratory behavior is modified by recent experiences via a memory process, and animals have a social swarming-like behavior over a range of spatial scales. We found that this relatively simple framework was able to adapt to a stable, seasonal resource dynamic under a broad range of parameter values. Furthermore, the model was able to acquire an adaptive migration behavior with time. However, the resilience of the process depended on all the parameters under consideration, with many complex trade-offs. For example, the spatial scale of sociality needed to be large enough to capture changes in the resource, but not so large that the acquired collective information was overly diluted. A long-term reference memory was important for hedging against a highly stochastic process, but a higher weighting of more recent memory was needed for adapting to directional changes in resource phenology. Our model provides a general and versatile framework for exploring the interaction of memory, movement, social and resource dynamics, even as environmental conditions globally are undergoing rapid change.

Historical Changes in Large River Fish Assemblages of the Americas

2005 ◽  
Keyword(s):  
Alien Species ◽  
Environmental Changes ◽  
Fish Assemblages ◽  
Fish Fauna ◽  
Large River ◽  
Gold Rush ◽  
Physical Habitat ◽  
San Joaquin River ◽  
The Status ◽  
Native Fishes

<em>Abstract.</em>—In this paper, we review information regarding the status of the native fishes of the combined Sacramento River and San Joaquin River drainages (hereinafter the “Sacramento–San Joaquin drainage”) and the factors associated with their declines. The Sacramento–San Joaquin drainage is the center of fish evolution in California, giving rise to 17 endemic species of a total native fish fauna of 28 species. Rapid changes in land use and water use beginning with the Gold Rush in the 1850s and continuing to the present have resulted in the extinction, extirpation, and reduction in range and abundance of the native fishes. Multiple factors are associated with the declines of native fishes, including habitat alteration and loss, water storage and diversion, flow alteration, water quality, and invasions of alien species. Although native fishes can be quite tolerant of stressful physical conditions, in some rivers of the drainage the physical habitat has been altered to the extent that it is now more suited for alien species. This interaction of environmental changes and invasions of alien species makes it difficult to predict the benefits of restoration efforts to native fishes. Possible effects of climate change on California’s aquatic habitats add additional complexity to restoration of native fishes. Unless protection and restoration of native fishes is explicitly considered in future water management decisions, declines are likely to continue.

scholarly journals Introduction. Integration of ecology and endocrinology in avian reproduction: a new synthesis

2007 ◽  
Vol 363 (1497) ◽  
pp. 1581-1588 ◽  
Author(s):  
John C Wingfield ◽  
Tony D Williams ◽  
Marcel E Visser
Keyword(s):  
Biological Sciences ◽  
Environmental Changes ◽  
Biological Knowledge ◽  
Avian Reproduction ◽  
Physiological Processes ◽  
Trade Offs ◽  
New Synthesis ◽  
Reproductive Life ◽  
Common Framework ◽  
Collaborative Efforts

Birds are some of the most familiar organisms of global ecosystems. Changes in the visibility and abundance of birds are therefore excellent indicators of population and physiological responses to habitat changes and are a major focus for public concern about detrimental environmental changes. In order to understand how birds respond to these challenges, it is essential to determine how the environment affects reproduction under natural conditions. The continuum from environmental variables (cues) to reproductive life-history traits depends upon a cascade of neural and physiological processes that determine the extent and rate at which birds will be able to adapt to changes in their environment. For a full understanding of this ability to adapt, ecologists and endocrinologists need to collaborate and build a common framework. The objective of this theme issue is to bring together a series of papers addressing how evolutionary ecologists and endocrinologists can collaborate directly using avian reproduction as a model system. First, we address the need to integrate ecology and endocrinology and what benefits to biological knowledge will be gained. The papers collected in this issue represent a new synthesis of ecology and endocrinology as discussed in three E-BIRD workshops. The three main foci are trade-offs and constraints, maternal effects and individual variation. Authors within each group present ecological and endocrinological aspects of their topics and many go on to outline testable hypotheses. Finally, we discuss where the major problems remain and how this issue points out where these need collaborative efforts of ecologists and endocrinologists. Specific challenges are raised to future researchers to break through intellectual barriers and explore new frontiers. This framework of topics will ultimately apply to all taxa because the principles involved are universal and hopefully will have direct application to programmes integrating organisms and genes throughout biological sciences.

scholarly journals A fauna de peixes nas bacias do norte do Espírito Santo, Brasil

2012 ◽  
Vol 12 (1) ◽  
pp. 27 ◽  
Author(s):  
Luisa Maria Sarmento-Soares ◽  
Ronaldo Fernando Martins-Pinheiro
Keyword(s):  
Environmental Changes ◽  
Sand Dunes ◽  
Fish Fauna ◽  
Distribution Patterns ◽  
Biological Indicators ◽  
Taxonomic Composition ◽  
Semiarid Region ◽  
Freshwater Species ◽  
Espírito Santo ◽  
Espirito Santo

The hydrographic basins of northern Espírito Santo comprises the systems of Itaúnas and São Mateus rivers. The present work is part of a series of studies on the fish fauna along Espírito Santo’s river basins. Forty-nine geo-referred points in rivers and rivulets of the area were evaluated, 20 in the Itaúnas basin and 28 in São Mateus basin. The environment and the taxonomic composition of the fish fauna were documented at every point, reporting a total of 83 species, including 47 freshwater species and 36 marine, belonging to 35 families and 11 orders. Among the freshwater fish species, the Siluriformes predominated, with 20 species, followed by the Characiformes, with 17 species. The Atlantic forest of northern Espírito Santo, known as “floresta de tabuleiros”, was originally composed of ombrophylous forest as well as swamps, coastal sand dunes, and mangroves. With the suppression of native forests, the region has suffered from desertification, and environmental conditions are similar to the northeastern semiarid region, where the run-off waters are dispersed or intermittent. The loss of environmental quality along river valleys is associated with the need to reestablish riverine aquatic conditions. Exotic species and risks of introductions need further studies in these areas. Rare or endangered species whose distributional range has diminished in response to environmental changes may function as biological indicators. Potentially new species are identified, and regional endemism and distribution patterns for freshwater fishes are discussed.

scholarly journals Evolutionary Medicine: The Ongoing Evolution of Human Physiology and Metabolism

Physiology ◽  
2016 ◽  
Vol 31 (6) ◽  
pp. 392-397 ◽  
Author(s):  
Frank Rühli ◽  
Katherine van Schaik ◽  
Maciej Henneberg
Keyword(s):  
Environmental Changes ◽  
Evolutionary Medicine ◽  
Human Anatomy ◽  
Anatomy And Physiology ◽  
Trade Offs ◽  
Human Anatomy And Physiology ◽  
Survival And Reproduction ◽  
Diachronic Study ◽  
Health And Disease ◽  
Over Time

The field of evolutionary medicine uses evolutionary principles to understand changes in human anatomy and physiology that have occurred over time in response to environmental changes. Through this evolutionary-based approach, we can understand disease as a consequence of anatomical and physiological “trade-offs” that develop to facilitate survival and reproduction. We demonstrate how diachronic study of human anatomy and physiology is fundamental for an increased understanding of human health and disease.

Population density in Podarcis lilfordi (Squamata, Lacertidae), a lizard species endemic to small islets in the Balearic Islands (Spain)

2008 ◽  
Vol 29 (1) ◽  
pp. 49-60 ◽  
Author(s):  
Valentín Pérez-Mellado ◽  
Javier Martín-Vallejo ◽  
Richard Brown ◽  
Antonia Picornell ◽  
José Castro ◽  
...  
Keyword(s):  
Rattus Rattus ◽  
Habitat Diversity ◽  
Balearic Islands ◽  
Lizard Species ◽  
Human Disturbances ◽  
Factors Affecting ◽  
Island Area ◽  
Podarcis Lilfordi ◽  
Independent Variable ◽  
Insular Populations

Abstract The Balearic lizard, Podarcis lilfordi, is present in 43 insular populations in the Cabrera archipelago and around the coasts of Mallorca and Menorca islands (Spain). We studied lizard densities over the entire range of distribution, analyzing observed differences of density in relation to island area, habitat diversity, availability of resources, presence of predators, competitors and human disturbances. The density of the Balearic lizard varies from less than 35 to almost 8000 lizards ha–1, with an average of around 1500 lizards ha–1. In some very small islets we detected no more than 10 individuals. Using a subsample of nine coastal islets (Menorca) we did not find any significant correlation between ground arthropod biomass and lizard density. The combination of island area and its maximal altitude, its so-called biotic capacity, was also uncorrelated with lizard density. In addition, neither degree of island accessibility nor presence/absence of seagull breeding colonies, were able to explain lizard densities. Islands without ship rats (Rattus rattus) showed a significantly higher lizard density, but islands in which rat eradication programs were launched during the study period, showed lower densities than those with rats but no eradication actions. Genetic variability was significantly higher on bigger lizard populations, lacking a correlation with lizard densities. No single independent variable can explain density differences among populations under study. Our results are discussed in the light of available hypotheses on factors affecting population densities.

scholarly journals Fast processing of environmental DNA metabarcoding sequence data using convolutional neural networks

2021 ◽  
Author(s):  
Benjamin Flück ◽  
Laëtitia Mathon ◽  
Stéphanie Manel ◽  
Alice Valentini ◽  
Tony Dejean ◽  
...  
Keyword(s):  
Neural Networks ◽  
Convolutional Neural Networks ◽  
Environmental Changes ◽  
Sequence Data ◽  
Mitochondrial Gene ◽  
Fish Fauna ◽  
Environmental Dna ◽  
Small Region ◽  
Anthropogenic Pressures ◽  
Speed And Accuracy

The intensification of anthropogenic pressures have increased consequences on biodiversity and ultimately on the functioning of ecosystems. To monitor and better understand biodiversity responses to environmental changes using standardized and reproducible methods, novel high-throughput DNA sequencing is becoming a major tool. Indeed, organisms shed DNA traces in their environment and this "environmental DNA" (eDNA) can be collected and sequenced using eDNA metabarcoding. The processing of large volumes of eDNA metabarcoding data remains challenging, especially its transformation to relevant taxonomic lists that can be interpreted by experts. Speed and accuracy are two major bottlenecks in this critical step. Here, we investigate whether convolutional neural networks (CNN) can optimize the processing of short eDNA sequences. We tested whether the speed and accuracy of a CNN are comparable to that of the frequently used OBITools bioinformatic pipeline. We applied the methodology on a massive eDNA dataset collected in Tropical South America (French Guiana), where freshwater fishes were targeted using a small region (60pb) of the 12S ribosomal RNA mitochondrial gene. We found that the taxonomic assignments from the CNN were comparable to those of OBITools, with high correlation levels and a similar match to the regional fish fauna. The CNN allowed the processing of raw fastq files at a rate of approximately 1 million sequences per minute which was ~150 times faster than with OBITools. Once trained, the application of CNN to new eDNA metabarcoding data can be automated, which promises fast and easy deployment on the cloud for future eDNA analyses.

scholarly journals Importance of Protection Service Against Erosion and Storm Events Provided by Coastal Ecosystems Under Climate Change Scenarios

2021 ◽  
Vol 8 ◽  
Author(s):  
Jacinto Cunha ◽  
Fábio Santos Cardona ◽  
Ana Bio ◽  
Sandra Ramos
Keyword(s):  
Climate Change ◽  
Extreme Events ◽  
Environmental Changes ◽  
Climate Change Scenarios ◽  
Northern Coast ◽  
Storm Events ◽  
Property Damage ◽  
Natural Habitats ◽  
Coastal Habitats ◽  
Trade Offs

Increasing sea level rise (SLR), and frequency and intensity of storms, paired with degrading ecosystems, are exposing coastal areas to higher risks of damage by storm events. Coastal natural habitats, such as dunes or saltmarshes, can reduce exposure of coastlines to these events and help to reduce the impacts and the potential damage to coastal property. The goal of our study was to evaluate the current vulnerability of the Portuguese northern coast to erosion and flooding caused by extreme events and to assess the contribution of natural habitats in reducing both vulnerability and property damages considering SLR scenarios. The Integrated Valuation of Environmental Services and Trade-offs (InVEST) Coastal Vulnerability model was used to produce an Exposure Index (EI) for the northern Portuguese coastline, for the current situation, and for future International Panel for Climate Change (IPCC) scenarios Representative Concentration Pathway (RCP) 2.6, RCP4.5, and RCP8.5, considering the presence and absence of coastal habitats. Results showed an increase in exposure with rising sea levels and expansion of high vulnerability areas. Coastal habitats contributed to a 28% reduction of high exposed segments for the Current scenario, corresponding to a potential reduction of coastal property damage of 105 M€ during extreme events. For the SLR scenarios, coastal habitats could potentially reduce the amount of property damage by 190 M€ in 2050 and 285 M€ in 2100, considering RCP8.5 projections. This study highlighted the importance of natural habitats in protecting vulnerable coastlines and reducing the potential damages to properties from flooding. Such results can be incorporated in management plans and support decision-making toward implementing an ecosystem-based approach to increase the resilience of coastal communities to cope with future environmental changes.

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