1
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Nakamoto BJ, Jeffres CA, Corline NJ, Ogaz M, Bradley CJ, Viers JH, Fogel ML. Multiple trophic pathways support fish on floodplains of California's Central Valley. JOURNAL OF FISH BIOLOGY 2023; 102:155-171. [PMID: 36226864 DOI: 10.1111/jfb.15248] [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: 04/08/2022] [Accepted: 10/10/2022] [Indexed: 06/16/2023]
Abstract
We used compound-specific isotope analysis of carbon isotopes in amino acids (AAs) to determine the biosynthetic source of AAs in fish from major tributaries to California's Sacramento-San Joaquin river delta (i.e., the Sacramento, Cosumnes and Mokelumne rivers). Using samples collected in winter and spring between 2016 and 2019, we confirmed that algae are a critical component of floodplain food webs in California's Central Valley. Results from bulk stable isotope analysis of carbon and nitrogen in producers and consumers were adequate to characterize a general trophic structure and identify potential upstream and downstream migration into our study site by American shad Alosa sapidissima and rainbow trout Oncorhynchus mykiss, respectively. However, owing to overlap and variability in source isotope compositions, our bulk data were unsuitable for conventional bulk isotope mixing models. Our results from compound-specific carbon isotope analysis of AAs clearly indicate that algae are important sources of organic matter to fish of conservation concern, such as Chinook salmon Oncorhynchus tshawytscha in California's Central Valley. However, algae were not the exclusive source of energy to metazoan food webs. We also revealed that other sources of AAs, such as bacteria, fungi and higher plants, contributed to fish as well. While consistent with the well-supported notion that algae are critical to aquatic food webs, our results highlight the possibility that detrital subsidies might intermittently support metazoan food webs.
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Affiliation(s)
| | | | | | - Mollie Ogaz
- Center for Watershed Sciences, UC Davis, Davis, California, USA
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2
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Arsenault ER, Thorp JH, Polito MJ, Minder M, Dodds WK, Tromboni F, Maasri A, Pyron M, Mendsaikhan B, Otgonganbat A, Altangerel S, Chandra S, Shields R, Artz C, Bennadji H. Intercontinental analysis of temperate steppe stream food webs reveals consistent autochthonous support of fishes. Ecol Lett 2022; 25:2624-2636. [PMID: 36223323 DOI: 10.1111/ele.14113] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 08/25/2022] [Accepted: 09/09/2022] [Indexed: 11/30/2022]
Abstract
Quantifying the trophic basis of production for freshwater metazoa at broad spatial scales is key to understanding ecosystem function and has been a research priority for decades. However, previous lotic food web studies have been limited by geographic coverage or methodological constraints. We used compound-specific stable carbon isotope analysis of amino acids (AAs) to estimate basal resource contributions to fish consumers in streams spanning grassland, montane and semi-arid ecoregions of the temperate steppe biome on two continents. Across a range of stream sizes and light regimes, we found consistent trophic importance of aquatic resources. Essential AAs of heterotrophic microbial origin generally provided secondary support for fishes, while terrestrial carbon did not seem to provide significant, direct support. These findings provide strong evidence for the dominant contribution of carbon to higher-order consumers by aquatic autochthonous resources (primarily) and heterotrophic microbial communities (secondarily) in temperate steppe streams.
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Affiliation(s)
- Emily R Arsenault
- Department of Environmental Biology, State University of New York College of Environmental Science and Forestry, Syracuse, New York, USA.,Program in Environmental Studies, Bates College, Lewiston, Maine, USA.,Kansas Biological Survey and Center for Ecological Research, University of Kansas, Lawrence, Kansas, USA.,Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas, USA
| | - James H Thorp
- Kansas Biological Survey and Center for Ecological Research, University of Kansas, Lawrence, Kansas, USA.,Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas, USA
| | - Michael J Polito
- Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge, Louisiana, USA
| | - Mario Minder
- Department of Biology, Ball State University, Muncie, Indiana, USA
| | - Walter K Dodds
- Division of Biology, Kansas State University, Kansas, USA
| | - Flavia Tromboni
- Department of Biology, Global Water Center, University of Nevada, Nevada, USA
| | - Alain Maasri
- Leibniz Institute of Freshwater Ecology and Inland Fisheries, Germany.,Academy of Natural Sciences, Drexel University, Pennsylvania, USA
| | - Mark Pyron
- Department of Biology, Ball State University, Muncie, Indiana, USA
| | - Bud Mendsaikhan
- Institute of Geography and Geoecology, Mongolian Academy of Sciences, Ulaanbaatar, Mongolia
| | - Amarbat Otgonganbat
- Ecology Program, Biological Department, National University of Mongolia, Mongolia
| | - Solongo Altangerel
- Institute of Geography and Geoecology, Mongolian Academy of Sciences, Ulaanbaatar, Mongolia.,Ecology Program, Biological Department, National University of Mongolia, Mongolia
| | - Sudeep Chandra
- Department of Biology, Global Water Center, University of Nevada, Nevada, USA
| | - Robert Shields
- Department of Biology, Ball State University, Muncie, Indiana, USA
| | - Caleb Artz
- Department of Biology, Ball State University, Muncie, Indiana, USA
| | - Hayat Bennadji
- Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge, Louisiana, USA
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3
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Wilkinson C, Lim RBH, Liew JH, Kwik JTB, Tan CLY, Heok Hui T, Yeo DCJ. Empirical food webs of 12 tropical reservoirs in Singapore. Biodivers Data J 2022; 10:e86192. [PMID: 36761616 PMCID: PMC9848559 DOI: 10.3897/bdj.10.e86192] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 08/16/2022] [Indexed: 11/12/2022] Open
Abstract
Background Food webs summarise trophic interactions of the biotic components within an ecosystem, which can influence nutrient dynamics and energy flows, ultimately affecting ecosystem functions and services. Food webs represent the hypothesised trophic links between predators and prey and can be presented as empirical food webs, in which the relative strength/importance of the respective links are quantified. Some common methods used in food web research include gut content analysis (GCA) and stable isotope analysis (SIA). We combine both methods to construct empirical food web models as a basis for monitoring and studying ecosystem-level outcomes of natural (e.g. species turnover in fish assemblage) and intentional environmental change (e.g. biomanipulation). New information We present 12 food webs from tropical reservoir communities in Singapore and summarise the topology of each with widely-used network indices (e.g. connectance, link density). Each reservoir was surveyed over 4-6 sampling occasions, during which, representative animal groups (i.e. fish species and taxonomic/functional groups of zooplankton and benthic macroinvertebrates) and all likely sources of primary production (i.e. macrophytes, periphyton, phytoplankton and riparian terrestrial plants) were collected. We analysed gut content in fishes and bulk isotope (d13C and d15N) profiles of all animals (i.e. fishes and invertebrates) and plants collected. Both sets of information were used to estimate the relative strength of trophic relationships using Bayesian mixing models. We document our protocol here, alongside a script in the R programming language for executing data management/analyses/visualisation procedures used in our study. These data can be used to glean insights into trends in inter- and intra-specific or guild interactions in analogous freshwater lake habitats.
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Affiliation(s)
- Clare Wilkinson
- National University of Singapore, Singapore, SingaporeNational University of SingaporeSingaporeSingapore
| | - Rayson B H Lim
- National University of Singapore, Singapore, SingaporeNational University of SingaporeSingaporeSingapore
| | - Jia Huan Liew
- Lingnan University, Hong Kong, ChinaLingnan UniversityHong KongChina
| | - Jeffrey T B Kwik
- National University of Singapore, Singapore, SingaporeNational University of SingaporeSingaporeSingapore
| | - Claudia L Y Tan
- National University of Singapore, Singapore, SingaporeNational University of SingaporeSingaporeSingapore
| | - Tan Heok Hui
- Lee Kong Chian Natural History Museum, National University of Singapore, Kent Ridge, SingaporeLee Kong Chian Natural History Museum, National University of SingaporeKent RidgeSingapore
| | - Darren C J Yeo
- National University of Singapore, Singapore, SingaporeNational University of SingaporeSingaporeSingapore,Lee Kong Chian Natural History Museum, National University of Singapore, Kent Ridge, SingaporeLee Kong Chian Natural History Museum, National University of SingaporeKent RidgeSingapore
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4
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Yun HY, Larsen T, Choi B, Won E, Shin K. Amino acid nitrogen and carbon isotope data: Potential and implications for ecological studies. Ecol Evol 2022; 12:e8929. [PMID: 35784034 PMCID: PMC9163675 DOI: 10.1002/ece3.8929] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 04/18/2022] [Accepted: 04/25/2022] [Indexed: 12/17/2022] Open
Abstract
Explaining food web dynamics, stability, and functioning depend substantially on understanding of feeding relations within a community. Bulk stable isotope ratios (SIRs) in natural abundance are well‐established tools to express direct and indirect feeding relations as continuous variables across time and space. Along with bulk SIRs, the SIRs of individual amino acids (AAs) are now emerging as a promising and complementary method to characterize the flow and transformation of resources across a diversity of organisms, from microbial domains to macroscopic consumers. This significant AA‐SIR capacity is based on empirical evidence that a consumer's SIR, specific to an individual AA, reflects its diet SIR coupled with a certain degree of isotopic differences between the consumer and its diet. However, many empirical ecologists are still unfamiliar with the scope of applicability and the interpretative power of AA‐SIR. To fill these knowledge gaps, we here describe a comprehensive approach to both carbon and nitrogen AA‐SIR assessment focusing on two key topics: pattern in AA‐isotope composition across spatial and temporal scales, and a certain variability of AA‐specific isotope differences between the diet and the consumer. On this basis we review the versatile applicability of AA‐SIR to improve our understanding of physiological processes as well as food web functioning, allowing us to reconstruct dominant basal dietary sources and trace their trophic transfers at the specimen and community levels. Given the insightful and opportunities of AA‐SIR, we suggest future applications for the dual use of carbon and nitrogen AA‐SIR to study more realistic food web structures and robust consumer niches, which are often very difficult to explain in nature.
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Affiliation(s)
- Hee Young Yun
- Deparment of Marine Science and Convergent Technology Hanyang University Ansan Korea
| | - Thomas Larsen
- Department of Archaeology Max Planck Institute for the Science of Human History Jena Germany
| | - Bohyung Choi
- Deparment of Marine Science and Convergent Technology Hanyang University Ansan Korea
- Inland Fisheries Research Institute National Institute of Fisheries Science Geumsan‐gun Korea
| | - Eun‐Ji Won
- Deparment of Marine Science and Convergent Technology Hanyang University Ansan Korea
| | - Kyung‐Hoon Shin
- Deparment of Marine Science and Convergent Technology Hanyang University Ansan Korea
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5
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Arsenault ER, Liew JH, Hopkins JR. Substrate Composition Influences Amino Acid Carbon Isotope Profiles of Fungi: Implications for Tracing Fungal Contributions to Food Webs. Environ Microbiol 2022; 24:2089-2097. [PMID: 35229441 DOI: 10.1111/1462-2920.15961] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 02/02/2022] [Accepted: 02/26/2022] [Indexed: 11/29/2022]
Abstract
Fungi link detrital resources and metazoan consumers through their role as decomposers. However, fungal contributions to metazoans may be misestimated in amino acid isotope studies because fungi are capable of both synthesizing amino acids (AAs) de novo and absorbing AAs from their environment. While fungi cultured in AA-free media have been used to represent fungi in studies of natural environments, fungi likely gain energetic benefits by taking up substrate AAs directly in situ. Consequently, fungi cultured on AA-free media may not be representative of the true variability of natural fungal δ13 CAA profiles. Therefore, the objective of this experiment was to determine the effect of substrate AA availability on yeast δ13 CAA profiles. We found that yeasts cultured in media of relatively higher AA content had different δ13 CAA profiles than fungi grown in AA-free media, in part because yeasts utilized two essential AAs (Leu and Val) directly from media substrates when available in sufficient amounts. Furthermore, these differences among yeast δ13 CAA profiles remained after normalization of δ13 CAA values. We recommend further characterization of the variation in fungal δ13 CAA profiles and the incorporation of this potential variability into interpretations of basal resource use by metazoans. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Emily R Arsenault
- Kansas Biological Survey and Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas, USA.,Program in Environmental Studies, Bates College, Lewiston, Maine, USA
| | - Jia Huan Liew
- Science Unit, Lingnan University, Tuen Mun, Hong Kong
| | - Jacob R Hopkins
- Kansas Biological Survey and Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas, USA.,Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus, Ohio, USA
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6
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Demars BOL, Kemp JL, Marteau B, Friberg N, Thornton B. Stream Macroinvertebrates and Carbon Cycling in Tangled Food Webs. Ecosystems 2021. [DOI: 10.1007/s10021-021-00626-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
AbstractThe annual global loss of organic carbon from terrestrial ecosystems into rivers is similar to the organic carbon stored in soils each year. Dissolved organic matter (DOM) flows through the food web to macroinvertebrates, but little is known about the effect of DOM increase on stream food webs and how much macroinvertebrates may contribute to the regulation of carbon fluxes in rivers. Using a before and after control impact (BACI) experimental design, we increased by 12% (+ 0.52 mg C L−1) the concentration of DOM in a stream for three weeks by adding sucrose, with a distinctive δ13C signature, to simulate a pulse of natural DOM supply from soils. We partitioned the diet of macroinvertebrates from carbon sources according to the green pathway (autotrophs) and detrital pathways (bacteria and terrestrial organic matter). Our flow food web approach based on C fluxes, with bacteria as a key node, showed the dominant contribution of the detrital pathways for macroinvertebrates in the reference stream. DOM addition induced changes in the diets of individual taxa, but did not have any strong effects on the relative overall contribution of the detrital pathways versus the green pathway. Autotrophic uptake of CO2 respired by bacteria was much larger than bacterial C flux to invertebrates (that is, the classic microbial loop) and allowed a significant fraction of natural allochthonous organic carbon to make its way to macroinvertebrates via autotrophs fixing CO2 respired by bacteria. Overall macroinvertebrates did not regulate directly to any great extent the flux of stream DOM towards downstream ecosystems.
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7
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Chua KWJ, Liew JH, Wilkinson CL, Ahmad AB, Tan HH, Yeo DCJ. Land-use change erodes trophic redundancy in tropical forest streams: Evidence from amino acid stable isotope analysis. J Anim Ecol 2021; 90:1433-1443. [PMID: 33666230 DOI: 10.1111/1365-2656.13462] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Accepted: 12/16/2020] [Indexed: 11/29/2022]
Abstract
Studies have shown that food chain length is governed by interactions between species richness, ecosystem size and resource availability. While redundant trophic links may buffer impacts of species loss on food chain length, higher extinction risks associated with predators may result in bottom-heavy food webs with shorter food chains. The lack of consensus in earlier empirical studies relating species richness and food chain length reflects the need to account robustly for the factors described above. In response to this, we conducted an empirical study to elucidate impacts of land-use change on food chain length in tropical forest streams of Southeast Asia. Despite species losses associated with forest loss at our study areas, results from amino acid isotope analyses showed that food chain length was not linked to land use, ecosystem size or resource availability. Correspondingly, species losses did not have a significant effect on occurrence likelihoods of all trophic guilds except herbivores. Impacts of species losses were likely buffered by initial high levels of trophic redundancy, which declined with canopy cover. Declines in trophic redundancy were most drastic amongst invertivorous fishes. Declines in redundancy across trophic guilds were also more pronounced in wider and more resource-rich streams. While our study found limited evidence for immediate land-use impacts on stream food chains, the potential loss of trophic redundancy in the longer term implies increasing vulnerability of streams to future perturbations, as long as land conversion continues unabated.
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Affiliation(s)
- Kenny W J Chua
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Jia Huan Liew
- School of Biological Sciences, The University of Hong Kong, Hong Kong SAR
| | - Clare L Wilkinson
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Amirrudin B Ahmad
- Faculty of Science and Marine Environment, Universiti Malaysia Terengganu, Terengganu, Malaysia.,Institute for Tropical Biodiversity and Sustainable Development, Universiti Malaysia Terengganu, Terengganu, Malaysia
| | - Heok Hui Tan
- Lee Kong Chian Natural History Museum, National University of Singapore, Singapore
| | - Darren C J Yeo
- Department of Biological Sciences, National University of Singapore, Singapore.,Lee Kong Chian Natural History Museum, National University of Singapore, Singapore
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8
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Skinner C, Mill AC, Fox MD, Newman SP, Zhu Y, Kuhl A, Polunin NVC. Offshore pelagic subsidies dominate carbon inputs to coral reef predators. SCIENCE ADVANCES 2021; 7:7/8/eabf3792. [PMID: 33608282 PMCID: PMC7895429 DOI: 10.1126/sciadv.abf3792] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 01/04/2021] [Indexed: 05/04/2023]
Abstract
Coral reefs were traditionally perceived as productive hot spots in oligotrophic waters. While modern evidence indicates that many coral reef food webs are heavily subsidized by planktonic production, the pathways through which this occurs remain unresolved. We used the analytical power of carbon isotope analysis of essential amino acids to distinguish between alternative carbon pathways supporting four key reef predators across an oceanic atoll. This technique separates benthic versus planktonic inputs, further identifying two distinct planktonic pathways (nearshore reef-associated plankton and offshore pelagic plankton), and revealing that these reef predators are overwhelmingly sustained by offshore pelagic sources rather than by reef sources (including reef-associated plankton). Notably, pelagic reliance did not vary between species or reef habitats, emphasizing that allochthonous energetic subsidies may have system-wide importance. These results help explain how coral reefs maintain exceptional productivity in apparently nutrient-poor tropical settings, but also emphasize their susceptibility to future ocean productivity fluctuations.
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Affiliation(s)
- C Skinner
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, UK.
- Department of Ocean Science and Hong Kong Branch of the Southern Marine Science and Engineering, Guangdong Laboratory (Guangzhou), The Hong Kong University of Science and Technology, Kowloon, Hong Kong
| | - A C Mill
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
| | - M D Fox
- Woods Hole Oceanographic Institution, 266 Woods Hole Rd, Woods Hole, MA 02543, USA
| | - S P Newman
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
- Banyan Tree Marine Lab, Vabbinfaru Resort, North Malé Atoll, Republic of Maldives
| | - Y Zhu
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
| | - A Kuhl
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
| | - N V C Polunin
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
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9
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Caldwell TJ, Chandra S, Feher K, Simmons JB, Hogan Z. Ecosystem response to earlier ice break-up date: Climate-driven changes to water temperature, lake-habitat-specific production, and trout habitat and resource use. GLOBAL CHANGE BIOLOGY 2020; 26:5475-5491. [PMID: 32602183 DOI: 10.1111/gcb.15258] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 05/19/2020] [Accepted: 06/06/2020] [Indexed: 06/11/2023]
Abstract
Climate warming has yielded earlier ice break-up dates in recent decades for lakes leading to water temperature increases, altered habitat, and both increases and decreases to ecosystem productivity. Within lakes, the effect of climate warming on secondary production in littoral and pelagic habitats remains unclear. The intersection of changing habitat productivity and warming water temperatures on salmonids is important for understanding how climate warming will impact mountain ecosystems. We develop and test a conceptual model that expresses how earlier ice break-up dates influence within lake habitat production, water temperatures and the habitat utilized by, resources obtained and behavior of salmonids in a mountain lake. We measured zoobenthic and zooplankton production from the littoral and pelagic habitats, thermal conditions, and the habitat use, resource use, and fitness of Brook Trout (Salvelinus fontinalis). We show that earlier ice break-up conditions created a "resource-rich" littoral-benthic habitat with increases in zoobenthic production compared to the pelagic habitat which decreased in zooplankton production. Despite the increases in littoral-benthic food resources, trout did not utilize littoral habitat or zoobenthic resources due to longer durations of warm water temperatures in the littoral zone. In addition, 87% of their resources were supported by the pelagic habitat during periods with earlier ice break-up when pelagic resources were least abundant. The decreased reliance on littoral-benthic resources during earlier ice break-up caused reduced fitness (mean reduction of 12 g) to trout. Our data show that changes to ice break-up drive multi-directional results for resource production within lake habitats and increase the duration of warmer water temperatures in food-rich littoral habitats. The increased duration of warmer littoral water temperatures reduces the use of energetically efficient habitats culminating in decreased trout fitness.
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Affiliation(s)
- Timothy J Caldwell
- Ecology, Evolution and Conservation Biology Graduate Program, University of Nevada, Reno, NV, USA
- Department of Biology, College of Science, University of Nevada, Reno, NV, USA
| | - Sudeep Chandra
- Ecology, Evolution and Conservation Biology Graduate Program, University of Nevada, Reno, NV, USA
- Department of Biology, College of Science, University of Nevada, Reno, NV, USA
- Global Water Center, University of Nevada, Reno, NV, USA
| | - Karly Feher
- Department of Biology, College of Science, University of Nevada, Reno, NV, USA
| | - James B Simmons
- Ecology, Evolution and Conservation Biology Graduate Program, University of Nevada, Reno, NV, USA
- Department of Biology, College of Science, University of Nevada, Reno, NV, USA
| | - Zeb Hogan
- Department of Biology, College of Science, University of Nevada, Reno, NV, USA
- Global Water Center, University of Nevada, Reno, NV, USA
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10
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Wilkinson CL, Chua KWJ, Fiala R, Liew JH, Kemp V, Hadi Fikri A, Ewers RM, Kratina P, Yeo DCJ. Forest conversion to oil palm compresses food chain length in tropical streams. Ecology 2020; 102:e03199. [PMID: 32969053 DOI: 10.1002/ecy.3199] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Revised: 05/18/2020] [Accepted: 07/20/2020] [Indexed: 11/11/2022]
Abstract
In Southeast Asia, biodiversity-rich forests are being extensively logged and converted to oil palm monocultures. Although the impacts of these changes on biodiversity are largely well documented, we know addition to samples we collected in 201 little about how these large-scale impacts affect freshwater trophic ecology. We used stable isotope analyses (SIA) to determine the impacts of land-use changes on the relative contribution of allochthonous and autochthonous basal resources in 19 stream food webs. We also applied compound-specific SIA and bulk-SIA to determine the trophic position of fish apex predators and meso-predators (invertivores and omnivores). There was no difference in the contribution of autochthonous resources in either consumer group (70-82%) among streams with different land-use type. There was no change in trophic position for meso-predators, but trophic position decreased significantly for apex predators in oil palm plantation streams compared to forest streams. This change in maximum food chain length was due to turnover in identity of the apex predator among land-use types. Disruption of aquatic trophic ecology, through reduction in food chain length and shift in basal resources, may cause significant changes in biodiversity as well as ecosystem functions and services. Understanding this change can help develop more focused priorities for mediating the negative impacts of human activities on freshwater ecosystems.
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Affiliation(s)
- Clare L Wilkinson
- Department of Biological Sciences, National University of Singapore, 16 Science Drive 4, Singapore, 117558, Singapore
| | - Kenny W J Chua
- Department of Biological Sciences, National University of Singapore, 16 Science Drive 4, Singapore, 117558, Singapore
| | - Roswitha Fiala
- School of Biological and Chemical Sciences, Queen Mary University London, London, E1 4DQ, UK
| | - Jia H Liew
- Department of Biological Sciences, National University of Singapore, 16 Science Drive 4, Singapore, 117558, Singapore.,School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
| | - Victoria Kemp
- School of Biological and Chemical Sciences, Queen Mary University London, London, E1 4DQ, UK
| | - Arman Hadi Fikri
- Institute for Tropical Biology and Conservation, Universiti Malaysia Sabah, Jalan UMS, Kota Kinabalu, 88400, Malaysia
| | - Robert M Ewers
- Department of Life Sciences, Imperial College London-Silwood Park, Buckhurst Road, Ascot, SL5 7PY, UK
| | - Pavel Kratina
- School of Biological and Chemical Sciences, Queen Mary University London, London, E1 4DQ, UK
| | - Darren C J Yeo
- Department of Biological Sciences, National University of Singapore, 16 Science Drive 4, Singapore, 117558, Singapore.,Lee Kong Chian Natural History Museum, National University of Singapore, 2 Conservatory Drive, Singapore, 117377, Singapore
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11
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Burian A, Nielsen JM, Hansen T, Bermudez R, Winder M. The potential of fatty acid isotopes to trace trophic transfer in aquatic food-webs. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190652. [PMID: 32536314 DOI: 10.1098/rstb.2019.0652] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Compound-specific isotope analyses (CSIA) of fatty acids (FA) constitute a promising tool for tracing energy flows in food-webs. However, past applications of FA-specific carbon isotope analyses have been restricted to a relatively coarse food-source separation and mainly quantified dietary contributions from different habitats. Our aim was to evaluate the potential of FA-CSIA to provide high-resolution data on within-system energy flows using algae and zooplankton as model organisms. First, we investigated the power of FA-CSIA to distinguish among four different algae groups, namely cyanobacteria, chlorophytes, haptophytes and diatoms. We found substantial within-group variation but also demonstrated that δ13C of several FA (e.g. 18:3ω3 or 18:4ω3) differed among taxa, resulting in group-specific isotopic fingerprints. Second, we assessed changes in FA isotope ratios with trophic transfer. Isotope fractionation was highly variable in daphnids and rotifers exposed to different food sources. Only δ13C of nutritionally valuable poly-unsaturated FA remained relatively constant, highlighting their potential as dietary tracers. The variability in fractionation was partly driven by the identity of food sources. Such systematic effects likely reflect the impact of dietary quality on consumers' metabolism and suggest that FA isotopes could be useful nutritional indicators in the field. Overall, our results reveal that the variability of FA isotope ratios provides a substantial challenge, but that FA-CSIA nevertheless have several promising applications in food-web ecology. This article is part of the theme issue 'The next horizons for lipids as 'trophic biomarkers': evidence and significance of consumer modification of dietary fatty acids'.
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Affiliation(s)
- Alfred Burian
- Department of Ecology, Environment and Plant Sciences, Stockholm University, 10691 Stockholm, Sweden.,Environmental Sustainability Research Centre, University of Derby, Derby DE22 1GB, UK
| | - Jens M Nielsen
- Department of Ecology, Environment and Plant Sciences, Stockholm University, 10691 Stockholm, Sweden
| | - Thomas Hansen
- Helmholtz Centre for Ocean Research Kiel (GEOMAR), Kiel, Germany
| | - Rafael Bermudez
- Facultad de Ingeniería Marítima, Ciencias Biológicas, Oceánicas y Recursos Naturales, Escuela Superior Politécnica del Litoral, ESPOL, Guayaquil, Ecuador
| | - Monika Winder
- Department of Ecology, Environment and Plant Sciences, Stockholm University, 10691 Stockholm, Sweden
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12
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Fox MD, Elliott Smith EA, Smith JE, Newsome SD. Trophic plasticity in a common reef‐building coral: Insights from δ13C analysis of essential amino acids. Funct Ecol 2019. [DOI: 10.1111/1365-2435.13441] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Michael D. Fox
- Center for Marine Biodiversity and Conservation Scripps Institution of Oceanography University of California San Diego La Jolla CA USA
| | | | - Jennifer E. Smith
- Center for Marine Biodiversity and Conservation Scripps Institution of Oceanography University of California San Diego La Jolla CA USA
| | - Seth D. Newsome
- Biology Department University of New Mexico Albuquerque NM USA
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Soto DX, Decru E, Snoeks J, Verheyen E, Van de Walle L, Bamps J, Mambo T, Bouillon S. Terrestrial contributions to Afrotropical aquatic food webs: The Congo River case. Ecol Evol 2019; 9:10746-10757. [PMID: 31624578 PMCID: PMC6787788 DOI: 10.1002/ece3.5594] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 07/08/2019] [Accepted: 07/26/2019] [Indexed: 12/13/2022] Open
Abstract
Understanding the degree to which aquatic and terrestrial primary production fuel tropical aquatic food webs remains poorly understood, and quantifying the relative contributions of autochthonous and allochthonous inputs is methodologically challenging. Carbon and nitrogen stable isotope ratios (δ 13C, δ 15N) can provide valuable insights about contributions of terrestrial resources and trophic position, respectively, but this approach has caveats when applied in typical complex natural food webs.Here, we used a combination of C, N, and H (δ 2H) stable isotope measurements and Bayesian mixing models to estimate the contribution of terrestrial (allochthonous) and aquatic (autochthonous) inputs to fish and invertebrate communities in the Congo River (and some tributaries).Overall, our results show that we gained power to distinguish sources by using a multiple tracer approach and we were able to discriminate aquatic versus terrestrial sources (esp. including hydrogen isotopes). Fish δ 2H values were clearly correlated with their food preferences and revealed a high level of variation in the degree of allochthony in these tropical aquatic communities.At the community level, it is clear that terrestrial C3 plants are an important source fueling the Congo River food web. However, in order to better constrain source contribution in these complex environments will require more robust constraints on stable isotope values of algal and methane-derived C sources.
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Affiliation(s)
- David X. Soto
- Department of Earth and Environmental SciencesKU LeuvenLeuvenBelgium
| | - Eva Decru
- Section Vertebrates, IchthyologyRoyal Museum for Central AfricaTervurenBelgium
| | - Jos Snoeks
- Section Vertebrates, IchthyologyRoyal Museum for Central AfricaTervurenBelgium
- Laboratory of Biodiversity and Evolutionary GenomicsKU LeuvenLeuvenBelgium
| | - Erik Verheyen
- OD Taxonomy and PhylogenyRoyal Belgian Institute of Natural SciencesBrusselsBelgium
- Department Biology, Evolutionary EcologyUniversity of AntwerpAntwerpenBelgium
| | - Lora Van de Walle
- Section Vertebrates, IchthyologyRoyal Museum for Central AfricaTervurenBelgium
| | - Jolien Bamps
- Section Vertebrates, IchthyologyRoyal Museum for Central AfricaTervurenBelgium
| | - Taylor Mambo
- Centre de Surveillance de la BiodiversitéUniversité de KisanganiKisanganiDemocratic Republic of Congo
| | - Steven Bouillon
- Department of Earth and Environmental SciencesKU LeuvenLeuvenBelgium
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