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Sasaki M, Kingsbury KM, Booth DJ, Nagelkerken I. Body size mediates trophic interaction strength of novel fish assemblages under climate change. J Anim Ecol 2024. [PMID: 38644583 DOI: 10.1111/1365-2656.14079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 02/07/2024] [Indexed: 04/23/2024]
Abstract
Ecological similarity plays an important role in biotic interactions. Increased body size similarity of competing species, for example, increases the strength of their biotic interactions. Body sizes of many exothermic species are forecast to be altered under global warming, mediating shifts in existing trophic interactions among species, in particular for species with different thermal niches. Temperate rocky reefs along the southeast coast of Australia are located in a climate warming hotspot and now house a mixture of temperate native fish species and poleward range-extending tropical fishes (vagrants), creating novel species assemblages. Here, we studied the relationship between body size similarity and trophic overlap between individual temperate native and tropical vagrant fishes. Dietary niche overlap between vagrant and native fish species increased as their body sizes converged, based on both stomach content composition (short-term diet), stable isotope analyses (integrated long-term diet) and similarity in consumed prey sizes. We conclude that the warming-induced faster growth rates of tropical range-extending fish species at their cool water ranges will continue to converge their body size towards and strengthen their degree of trophic interactions and dietary overlap with co-occurring native temperate species under increasing ocean warming. The strengthening of these novel competitive interactions is likely to drive changes to temperate food web structures and reshuffle existing species community structures.
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Affiliation(s)
- Minami Sasaki
- Southern Seas Ecology Laboratories, School of Biological Sciences, The University of Adelaide, Adelaide, South Australia, Australia
| | - Kelsey M Kingsbury
- Southern Seas Ecology Laboratories, School of Biological Sciences, The University of Adelaide, Adelaide, South Australia, Australia
| | - David J Booth
- Fish Ecology Lab, Faculty of Science, University of Technology Sydney, Sydney, New South Wales, Australia
| | - Ivan Nagelkerken
- Southern Seas Ecology Laboratories, School of Biological Sciences, The University of Adelaide, Adelaide, South Australia, Australia
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Keppeler FW, Andrade MC, Trindade PAA, Sousa LM, Arantes CC, Winemiller KO, Jensen OP, Giarrizzo T. Early impacts of the largest Amazonian hydropower project on fish communities. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 838:155951. [PMID: 35588808 DOI: 10.1016/j.scitotenv.2022.155951] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 05/04/2022] [Accepted: 05/11/2022] [Indexed: 06/15/2023]
Abstract
Hydropower is a threat to freshwater fishes. Despite a recent boom in dam construction, few studies have assessed their impact on mega-diverse tropical rivers. Using a before-after study design, we investigated the early impacts of the Belo Monte hydroelectric complex, the third-largest hydropower project in the world, on fishes of the Xingu River, a major clear-water tributary of the lower Amazon. We explored impacts across different river sectors (upstream, reservoir, reduced flow sector, and downstream) and spatial scales (individual sectors vs. all sectors combined) using joint species distribution models and different facets of diversity (taxonomic, functional, and phylogenetic). After 5 years of the Belo Monte operation, species richness declined ~12% in lentic and ~16% in lotic environments. Changes in abundance were of less magnitude (<4%). Effects were particularly negative for species of the families Serrasalmidae (mainly pacus), Anostomidae (headstanders), Auchenipteridae, and Pimelodidae (catfishes), whereas no taxonomic group consistently increased in richness or abundance. The reservoir and downstream sectors were the most impacted, with declines of ~24-29% in fish species richness, overall reductions in fish body size and trophic level, and a change in average body shape. Richness and abundance also declined in the reduced river flow, and changes in size, shape, and position of fins were observed. Relatively minor changes were found in the upstream sector. Variation in functional and phylogenetic diversity following river impoundment was subtle; however, across sectors, we found a reduction in functional divergence, indicating a decline in the abundance of species located near the extremities of community functional space. This may be the first sign of an environmental filtering process reducing functional diversity in the region. Greater changes in flow and habitats are expected as hydropower operations ramp up, and continued monitoring is warranted to understand the full scope and magnitude of ecological impacts.
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Affiliation(s)
- Friedrich W Keppeler
- Center for Limnology, University of Wisconsin-Madison, Madison, WI, USA; Núcleo de Ecologia Aquática e Pesca da Amazônia, Federal University of Pará, Belém, Pará, Brazil.
| | - Marcelo C Andrade
- Núcleo de Ecologia Aquática e Pesca da Amazônia, Federal University of Pará, Belém, Pará, Brazil
| | - Paulo A A Trindade
- Núcleo de Ecologia Aquática e Pesca da Amazônia, Federal University of Pará, Belém, Pará, Brazil
| | - Leandro M Sousa
- Laboratório de Ictiologia de Altamira, Federal University of Pará, Altamira, Pará, Brazil
| | - Caroline C Arantes
- Division of Forestry and Natural Resources, West Virginia University, Morgantown, WV, USA
| | - Kirk O Winemiller
- Department of Ecology and Conservation Biology, Texas A&M University, College Station, TX, USA
| | - Olaf P Jensen
- Center for Limnology, University of Wisconsin-Madison, Madison, WI, USA
| | - Tommaso Giarrizzo
- Núcleo de Ecologia Aquática e Pesca da Amazônia, Federal University of Pará, Belém, Pará, Brazil; Instituto de Ciências do Mar (LABOMAR), Federal University of Ceará, Fortaleza, Brazil
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Dalu T, Cuthbert RN, Moyo S, Wasserman RJ, Chari LD, Weyl OLF, Jackson MC. Invasive carp alter trophic niches of consumers and basal resources in African reservoirs. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 813:152625. [PMID: 34963595 DOI: 10.1016/j.scitotenv.2021.152625] [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: 12/05/2021] [Accepted: 12/19/2021] [Indexed: 06/14/2023]
Abstract
Environmental pollution and biological invasions are key drivers of biodiversity change. However, the effects of invasion and pollution on food webs remain largely unexplored. Here, we used stable isotopes to examine the effects of common carp Cyprinus carpio and pollution on trophic dynamics in six small reservoirs. Our results revealed that the trophic niche widths of invertebrates, vertebrates, and invasive carp did not significantly differ among reservoirs with different pollution statuses. However, we found low niche conservatism among reservoirs, suggesting that while niche width may remain consistent, there is a shift in the position of the niches in isotopic space under both pollution and invasion scenarios. Niche conservatism among reservoirs was generally higher in invertebrates, but this was also regardless of reservoir condition (i.e. presence or absence of pollution and invasion). These results suggest that invasion by species coupled with organic pollution may cause subtle yet differing effects on components of a food web (basal end-members, invertebrates and vertebrates). Our findings provide a baseline measure of the potential in the development of detection and response strategies for carp invasions and organic pollution.
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Affiliation(s)
- Tatenda Dalu
- School of Biology and Environmental Sciences, University of Mpumalanga, Nelspruit 1200, South Africa; South African Institute for Aquatic Biodiversity, Makhanda 6140, South Africa; Wissenschaftskolleg zu Berlin Institute for Advanced Study, Berlin 14193, Germany.
| | - Ross N Cuthbert
- South African Institute for Aquatic Biodiversity, Makhanda 6140, South Africa; GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel, 24105 Kiel, Germany
| | - Sydney Moyo
- Department of Biology and Program in Environmental Studies and Sciences, Rhodes College, Memphis, TN 38112, USA
| | - Ryan J Wasserman
- Department of Zoology and Entomology, Rhodes University, Makhanda 6140, South Africa; South African Institute for Aquatic Biodiversity, Makhanda 6140, South Africa
| | - Lenin D Chari
- Department of Zoology and Entomology, Rhodes University, Makhanda 6140, South Africa; Centre for Biological Control, Department of Zoology and Entomology, Rhodes University, Makhanda 6140, South Africa
| | - Olaf L F Weyl
- South African Institute for Aquatic Biodiversity, Makhanda 6140, South Africa
| | - Michelle C Jackson
- Department of Zoology, University of Oxford, Oxford OX1 3SZ, United Kingdom
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Incorporating indirect pathways in body size-trophic position relationships. Oecologia 2020; 194:177-191. [PMID: 32940775 DOI: 10.1007/s00442-020-04752-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 09/08/2020] [Indexed: 10/23/2022]
Abstract
Body size, trophic position (TP), and trophic niche width are important elements of food webs; however, there is still debate regarding their interrelationships. Most studies have tested these correlations using datasets restricted to carnivores and bivariate models that disregard potential indirect effects of other factors, their interactions, and phylogeny. We analyzed relationships among TP, consumer size, maximum food item size, food item size variation (a proxy for trophic niche width), and two other traits (gut length and mouth width) using confirmatory path analysis of an extensive dataset for freshwater fishes that encompass both carnivorous and non-carnivorous species. Consumer size was associated with maximum food size, food size variation, mouth width, and gut length, all of which mediated indirect relationships between body size and TP. Mouth gape was associated with maximum food size, and consumers that fed on larger food items had higher TP. Consumers with relatively long guts generally fed on small and homogeneous food items near the base of the food web. Models were consistent whether or not accounting for phylogeny, but varied according to trophic guilds. However, the body size of both carnivorous and non-carnivorous was not directly associated with TP. Therefore, the incorporation of functional traits and their intermediate pathways is critical for understanding size-based trophic relationships of animals that encompass diverse feeding strategies. Our results caution approaches that rely on body size as a surrogate for TP, especially in systems where plants and detritus are consumed directly by a significant number of animals, such as in most freshwater ecosystems.
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