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Arocena R, Castro M, Chalar G. Ecological integrity assessment of streams in the light of natural ecoregions and anthropic land use. ENVIRONMENTAL MONITORING AND ASSESSMENT 2022; 194:748. [PMID: 36070011 DOI: 10.1007/s10661-022-10422-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 08/30/2022] [Indexed: 06/15/2023]
Abstract
Reference conditions for river bioassessment should be established inside ecoregions. Our objectives were (1) to implement a bioassessment methodology for Uruguayan prairie streams regarding ecoregions and land use and (2) to assess the ecological integrity of streams of the Río Negro basin in Uruguay. Due to logistical constraints, sampling was divided into two collection trips: one including the upper basin in fall 2015 and the other including the lower basin in spring 2016. Basins were analyzed separately due to seasonal and geographical differences. In the streams sampled in fall 2015, conductivity, total nitrogen (TN), and total phosphorus (TP) were higher in sedimentary ecoregions than in crystalline ones, independent on land use. In those sampled in spring 2016, these variables showed the highest values in the ecoregions dominated by agriculture. Eighty percent of the sampled streams presented the impact of cattle in their riparian zone. Discriminant analysis showed a similar composition of macroinvertebrates among ecoregions in 2015, but different composition between land uses. Conversely, in 2016, there were differences among some ecoregions, but not between land uses. Agriculture was correlated with tolerant invertebrates, while natural land use and afforestation were correlated with sensitive ones. The BMWP-Colombia showed the impact of livestock on streams, but in general good water quality, while an index of genera for Uruguay, indicated that all streams are eutrophic, thereby confirming the importance of using different types of metrics. Due to its geographical homogeneity and small size, a smaller number of ecoregions could be defined for stream assessments in the Río Negro basin.
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Affiliation(s)
- Rafael Arocena
- Facultad de Ciencias, Sección Limnología, Universidad de la República, Iguá 4225, 11400, Montevideo, Uruguay.
| | - Manuel Castro
- Facultad de Ciencias, Sección Limnología, Universidad de la República, Iguá 4225, 11400, Montevideo, Uruguay
| | - Guillermo Chalar
- Facultad de Ciencias, Sección Limnología, Universidad de la República, Iguá 4225, 11400, Montevideo, Uruguay
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Sandor ME, Elphick CS, Tingley MW. Extinction of biotic interactions due to habitat loss could accelerate the current biodiversity crisis. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2022; 32:e2608. [PMID: 35366031 DOI: 10.1002/eap.2608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 11/29/2021] [Accepted: 12/21/2021] [Indexed: 06/14/2023]
Abstract
Habitat loss disrupts species interactions through local extinctions, potentially orphaning species that depend on interacting partners, via mutualisms or commensalisms, and increasing secondary extinction risk. Orphaned species may become functionally or secondarily extinct, increasing the severity of the current biodiversity crisis. While habitat destruction is a major cause of biodiversity loss, the number of secondary extinctions is largely unknown. We investigate the relationship between habitat loss, orphaned species, and bipartite network properties. Using a real seed dispersal network, we simulate habitat loss to estimate the rate at which species are orphaned. To be able to draw general conclusions, we also simulate habitat loss in synthetic networks to quantify how changes in network properties affect orphan rates across broader parameter space. Both real and synthetic network simulations show that even small amounts of habitat loss can cause up to 10% of species to be orphaned. More area loss, less connected networks, and a greater disparity in the species richness of the network's trophic levels generally result in more orphaned species. As habitat is lost to land-use conversion and climate change, more orphaned species increase the loss of community-level and ecosystem functions. However, the potential severity of repercussions ranges from minimal (no species orphaned) to catastrophic (up to 60% of species within a network orphaned). Severity of repercussions also depends on how much the interaction richness and intactness of the community affects the degree of redundancy within networks. Orphaned species could add substantially to the loss of ecosystem function and secondary extinction worldwide.
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Affiliation(s)
- Manette E Sandor
- Ecology & Evolutionary Biology, University of Connecticut, Storrs, Connecticut, USA
- Northern Arizona University, Landscape Conservation Initiative, Flagstaff, Arizona, USA
- Department of Ecology, Evolution, and Environmental Biology, Columbia University, New York, New York, USA
- Center for Biodiversity and Conservation, American Museum of Natural History, New York, New York, USA
| | - Chris S Elphick
- Ecology & Evolutionary Biology, University of Connecticut, Storrs, Connecticut, USA
| | - Morgan W Tingley
- Ecology & Evolutionary Biology, University of Connecticut, Storrs, Connecticut, USA
- Ecology and Evolutionary Biology, University of California, Los Angeles, California, USA
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Zipkin EF, DiRenzo GV. Biodiversity is decimated by the cascading effects of the amphibian-killing chytrid fungus. PLoS Pathog 2022; 18:e1010624. [PMID: 35862362 PMCID: PMC9302726 DOI: 10.1371/journal.ppat.1010624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Affiliation(s)
- Elise F. Zipkin
- Department of Integrative Biology; Ecology, Evolution, and Behavior Program, Michigan State University, East Lansing, Michigan, United States of America
- * E-mail:
| | - Graziella V. DiRenzo
- U.S. Geological Survey, Massachusetts Cooperative Fish and Wildlife Research Unit, University of Massachusetts, Amherst, Massachusetts, United States of America
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Alp M, Cucherousset J. Food webs speak of human impact: Using stable isotope-based tools to measure ecological consequences of environmental change. FOOD WEBS 2022. [DOI: 10.1016/j.fooweb.2021.e00218] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Farine DR. Structural trade-offs can predict rewiring in shrinking social networks. J Anim Ecol 2019; 90:120-130. [PMID: 31691962 DOI: 10.1111/1365-2656.13140] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 10/24/2019] [Indexed: 11/30/2022]
Abstract
There is growing evidence that organisms can respond to declining population sizes by adapting their interactions with others. Regulating connections with others could underpin resilience of biological networks spanning from social groups to ecological communities. However, our ability to predict the dynamics of shrinking social networks remains limited. Network regulation involves several trade-offs. Removing nodes (and therefore their connections) from networks reduces the number of connections among remaining nodes. Responding by forming new connections then impacts other network properties. A simple way to minimize the impact of up-regulating network connections is to form new connections or to strengthen connections, between nodes that share a lost connection with a recently removed node. I propose a simple 'second-degree rewiring' rule as a biologically plausible regulatory mechanism in shrinking social networks. I argue that two individuals that have lost a connection with a common removed individual will both be more likely, or more willing, to form a new, or strengthen an existing, connection among themselves. I then show that such second-degree rewiring has less impact on important structural properties of the network than forming random new connections. For example, in a network with phenotypic assortment, second-degree nodes are more likely to be similar than any random pair of nodes, and connecting these will better maintain assortativity. This simple rule can therefore maintain network properties without individuals having any knowledge of the global structure of the network or the relative properties of the nodes within it. In this paper, I outline an algorithm for second-degree rewiring. I demonstrate how second-degree rewiring can have less impact than adding new, or increasing the strength of, random connections on both the individual and whole network properties. That is, relative to randomly adding or strengthening connections, second-degree rewiring has less impact on mean degree, assortativity, clustering and network density. I then demonstrate empirically, using social networks of great tits (Parus major), that individuals that previously shared connections to a removed conspecific were more likely to form a new connection or to strengthen their connection, relative to other individuals in the same population. This study highlights how developing a better mechanistic understanding of the structural properties of networks, and the consequences of adding new connections, can provide useful insights into how organisms are likely to regulate their interactions in shrinking populations.
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Affiliation(s)
- Damien R Farine
- Department of Collective Behavior, Max Planck Institute of Animal Behavior, Konstanz, Germany.,Department of Biology, University of Konstanz, Konstanz, Germany.,Center for the Advanced Study of Collective Behaviour, University of Konstanz, Konstanz, Germany.,Department of Zoology, Edward Grey Institute of Field Ornithology, University of Oxford, Oxford, UK
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Benke AC. River food webs: an integrative approach to bottom-up flow webs, top-down impact webs, and trophic position. Ecology 2018; 99:1370-1381. [PMID: 29604060 DOI: 10.1002/ecy.2228] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 01/30/2018] [Accepted: 03/02/2018] [Indexed: 11/11/2022]
Abstract
The majority of food web studies are based on connectivity, top-down impacts, bottom-up flows, or trophic position (TP), and ecologists have argued for decades which is best. Rarely have any two been considered simultaneously. The present study uses a procedure that integrates the last three approaches based on taxon-specific secondary production and gut analyses. Ingestion flows are quantified to create a flow web and the same data are used to quantify TP for all taxa. An individual predator's impacts also are estimated using the ratio of its ingestion (I) of each prey to prey production (P) to create an I/P web. This procedure was applied to 41 invertebrate taxa inhabiting submerged woody habitat in a southeastern U.S. river. A complex flow web starting with five basal food resources had 462 flows >1 mg·m-2 ·yr-1 , providing far more information than a connectivity web. Total flows from basal resources to primary consumers/omnivores were dominated by allochthonous amorphous detritus and ranged from 1 to >50,000 mg·m-2 ·yr-1 . Most predator-prey flows were much lower (<50 mg·m-2 ·yr-1 ), but some were >1,000 mg·m-2 ·yr-1 . The I/P web showed that 83% of individual predator impacts were weak (<10%), whereas total predator impacts were often strong (e.g., 35% of prey sustained an impact >90%). Quantitative estimates of TP ranged from 2 to 3.7, contrasting sharply with seven integer-based trophic levels based on longest feeding chain. Traditional omnivores (TP = 2.4-2.9) played an important role by consuming more prey and exerting higher impacts on primary consumers than strict predators (TP ≥ 3). This study illustrates how simultaneous quantification of flow pathways, predator impacts, and TP together provide an integrated characterization of natural food webs.
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Affiliation(s)
- Arthur C Benke
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama, 35487, USA
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Ocock JF, Brandis KJ, Wolfenden BJ, Jenkins KM, Wassens S. Gut content and stable isotope analysis of tadpoles in floodplain wetlands. AUST J ZOOL 2018. [DOI: 10.1071/zo18043] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Larval amphibians (tadpoles) are an important link in aquatic food webs, as they can be highly abundant consumers and prey for a wide variety of predators. Most tadpoles are considered omnivores, predominately grazing on algae, detritus and macrophytes, though recent work has identified greater plasticity and breadth in diet than previously considered. We used gut content and stable isotope analysis (SIA) in a baseline study to determine the important dietary items (ingested material) and food sources (assimilated material) for tadpoles of two abundant generalist frog species in regulated floodplain wetlands of the Murrumbidgee River, south-east Australia. We identified a wide variety of dietary items in the gut contents, including whole microcrustaceans, filamentous algae and macrophytes. The composition of several ingested food items was correlated with their availability in each wetland. However, SIA identified biofilm as the food source most consistently assimilated across several wetlands, though microcrustaceans and algae contributed when abundant. Biofilm is likely the most important basal food item for tadpoles in floodplain wetlands because it is ubiquitous and has a high nutritional quality. Identifying important food sources is a crucial step towards developing management strategies for promoting tadpole recruitment in regulated wetlands.
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DiRenzo GV, Che-Castaldo C, Rugenski A, Brenes R, Whiles MR, Pringle CM, Kilham SS, Lips KR. Disassembly of a tadpole community by a multi-host fungal pathogen with limited evidence of recovery. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2017; 27:309-320. [PMID: 28052493 DOI: 10.1002/eap.1443] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 07/28/2016] [Accepted: 08/24/2016] [Indexed: 06/06/2023]
Abstract
Emerging infectious diseases can cause host community disassembly, but the mechanisms driving the order of species declines and extirpations following a disease outbreak are unclear. We documented the community disassembly of a Neotropical tadpole community during a chytridiomycosis outbreak, triggered by the generalist fungal pathogen, Batrachochytrium dendrobatidis (Bd). Within the first 11 months of Bd arrival, tadpole density and occupancy rapidly declined. Species rarity, in terms of tadpole occupancy and adult relative abundance, did not predict the odds of tadpole occupancy declines. But species losses were taxonomically selective, with glassfrogs (Family: Centrolenidae) disappearing the fastest and tree frogs (Family: Hylidae) and dart-poison frogs (Family: Dendrobatidae) remaining the longest. We detected biotic homogenization of tadpole communities, with post-decline communities resembling one another more strongly than pre-decline communities. The entire tadpole community was extirpated within 22 months following Bd arrival, and we found limited signs of recovery within 10 years post-outbreak. Because of imperfect species detection inherent to sampling species-rich tropical communities and the difficulty of devising a single study design protocol to sample physically complex tropical habitats, we used simulations to provide recommendations for future surveys to adequately sample diverse Neotropical communities. Our unique data set on tadpole community composition before and after Bd arrival is a valuable baseline for assessing amphibian recovery. Our results are of direct relevance to conservation managers and community ecologists interested in understanding the timing, magnitude, and consequences of disease outbreaks as emerging infectious diseases spread globally.
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Affiliation(s)
- Graziella V DiRenzo
- Department of Biology, University of Maryland, College Park, Maryland, 20744, USA
| | | | - Amanda Rugenski
- School of Life Sciences, Arizona State University, Tempe, Arizona, 85281, USA
| | - Roberto Brenes
- Department of Biology, Carroll University, Waukesha, Wisconsin, 53186, USA
| | - Matt R Whiles
- Department of Zoology and Center for Ecology, Southern Illinois University, Carbondale, Illinois, 62901, USA
| | | | - Susan S Kilham
- Department of Biodiversity, Earth and Environmental Science, Drexel University, Philadelphia, Pennsylvania, 19104, USA
| | - Karen R Lips
- Department of Biology, University of Maryland, College Park, Maryland, 20744, USA
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Atkinson CL, Capps KA, Rugenski AT, Vanni MJ. Consumer-driven nutrient dynamics in freshwater ecosystems: from individuals to ecosystems. Biol Rev Camb Philos Soc 2016; 92:2003-2023. [DOI: 10.1111/brv.12318] [Citation(s) in RCA: 124] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 11/14/2016] [Accepted: 11/18/2016] [Indexed: 11/27/2022]
Affiliation(s)
- Carla L. Atkinson
- Department of Biological Sciences; University of Alabama; Tuscaloosa AL 35487 U.S.A
| | - Krista A. Capps
- Odum School of Ecology; University of Georgia; Athens GA 30602 U.S.A
- Savannah River Ecology Laboratory; University of Georgia; Aiken SC 29808 U.S.A
| | - Amanda T. Rugenski
- Department of Ecology and Evolutionary Biology; Cornell University; Ithaca NY 14853 U.S.A
| | - Michael J. Vanni
- Department of Biology and Graduate Program in Ecology Evolution and Environmental Biology; Miami University; Oxford OH 45056 U.S.A
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