1
|
Monk CT, Power M, Freitas C, Harrison PM, Heupel M, Kuparinen A, Moland E, Simpfendorfer C, Villegas-Ríos D, Olsen EM. Atlantic cod individual spatial behaviour and stable isotope associations in a no-take marine reserve. J Anim Ecol 2023; 92:2333-2347. [PMID: 37843043 DOI: 10.1111/1365-2656.14014] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 09/15/2023] [Indexed: 10/17/2023]
Abstract
Foraging is a behavioural process and, therefore, individual behaviour and diet are theorized to covary. However, few comparisons of individual behaviour type and diet exist in the wild. We tested whether behaviour type and diet covary in a protected population of Atlantic cod, Gadus morhua. Working in a no-take marine reserve, we could collect data on natural behavioural variation and diet choice with minimal anthropogenic disturbance. We inferred behaviour using acoustic telemetry and diet from stable isotope compositions (expressed as δ13 C and δ15 N values). We further investigated whether behaviour and diet could have survival costs. We found cod with shorter diel vertical migration distances fed at higher trophic levels. Cod δ13 C and δ15 N values scaled positively with body size. Neither behaviour nor diet predicted survival, indicating phenotypic diversity is maintained without survival costs for cod in a protected ecosystem. The links between diet and diel vertical migration highlight that future work is needed to understand whether the shifts in this behaviour during environmental change (e.g. fishing or climate), could lead to trophic cascades.
Collapse
Affiliation(s)
- Christopher T Monk
- Institute of Marine Research, Flødevigen Marine Research Station, His, Norway
- Centre for Coastal Research, Department of Natural Sciences, University of Agder, Kristiansand, Norway
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
| | - Michael Power
- Biology Department, University of Waterloo, Waterloo, Ontario, Canada
| | - Carla Freitas
- Institute of Marine Research, Flødevigen Marine Research Station, His, Norway
- MARE, Marine and Environmental Sciences Center, Madeira Tecnopolo, Funchal, Madeira, Portugal
| | - Philip M Harrison
- Department of Biology and Faculty of Forestry and Environmental Management, Canadian Rivers Institute, University of New Brunswick, Fredericton, New Brunswick, Canada
| | - Michelle Heupel
- Integrated Marine Observing System (IMOS), University of Tasmania, Hobart, Tasmania, Australia
| | - Anna Kuparinen
- Department of Biological and Environmental Sciences, University of Jyväskylä, Jyväskylä, Finland
| | - Even Moland
- Institute of Marine Research, Flødevigen Marine Research Station, His, Norway
- Centre for Coastal Research, Department of Natural Sciences, University of Agder, Kristiansand, Norway
| | - Colin Simpfendorfer
- College of Science and Engineering, James Cook University, Townsville, Queensland, Australia
| | | | - Esben M Olsen
- Institute of Marine Research, Flødevigen Marine Research Station, His, Norway
- Centre for Coastal Research, Department of Natural Sciences, University of Agder, Kristiansand, Norway
| |
Collapse
|
2
|
Inferences to estimate consumer’s diet using stable isotopes: Insights from a dynamic mixing model. PLoS One 2022; 17:e0263454. [PMID: 35130334 PMCID: PMC8820609 DOI: 10.1371/journal.pone.0263454] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 01/19/2022] [Indexed: 12/04/2022] Open
Abstract
Stable isotope ratios are used to reconstruct animal diet in trophic ecology via mixing models. Several assumptions of stable isotope mixing models are critical, i.e., constant trophic discrimination factor and isotopic equilibrium between the consumer and its diet. The isotopic turnover rate (λ and its counterpart the half-life) affects the dynamics of isotopic incorporation for an organism and the isotopic equilibrium assumption: λ involves a time lag between the real assimilated diet and the diet estimated by mixing models at the individual scale. Current stable isotope mixing model studies consider neither this time lag nor even the dynamics of isotopic ratios in general. We developed a mechanistic framework using a dynamic mixing model (DMM) to assess the contribution of λ to the dynamics of isotopic incorporation and to estimate the bias induced by neglecting the time lag in diet reconstruction in conventional static mixing models (SMMs). The DMM includes isotope dynamics of sources (denoted δs), λ and frequency of diet-switch (ω). The results showed a significant bias generated by the SMM compared to the DMM (up to 50% of differences). This bias can be strongly reduced in SMMs by averaging the isotopic variations of the food sources over a time window equal to twice the isotopic half-life. However, the bias will persist (∼15%) for intermediate values of the ω/λ ratio. The inferences generated using a case study highlighted that DMM enhanced estimates of consumer’s diet, and this could avoid misinterpretation in ecosystem functioning, food-web structure analysis and underlying biological processes.
Collapse
|
3
|
Kristensen ML, Olsen EM, Moland E, Knutsen H, Grønkjær P, Koed A, Källo K, Aarestrup K. Disparate movement behavior and feeding ecology in sympatric ecotypes of Atlantic cod. Ecol Evol 2021; 11:11477-11490. [PMID: 34429934 PMCID: PMC8366838 DOI: 10.1002/ece3.7939] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Revised: 07/02/2021] [Accepted: 07/05/2021] [Indexed: 12/19/2022] Open
Abstract
Coexistence of ecotypes, genetically divergent population units, is a widespread phenomenon, potentially affecting ecosystem functioning and local food web stability. In coastal Skagerrak, Atlantic cod (Gadus morhua) occur as two such coexisting ecotypes. We applied a combination of acoustic telemetry, genotyping, and stable isotope analysis to 72 individuals to investigate movement ecology and food niche of putative local "Fjord" and putative oceanic "North Sea" ecotypes-thus named based on previous molecular studies. Genotyping and individual origin assignment suggested 41 individuals were Fjord and 31 were North Sea ecotypes. Both ecotypes were found throughout the fjord. Seven percent of Fjord ecotype individuals left the study system during the study while 42% of North Sea individuals left, potentially homing to natal spawning grounds. Home range sizes were similar for the two ecotypes but highly variable among individuals. Fjord ecotype cod had significantly higher δ13C and δ15N stable isotope values than North Sea ecotype cod, suggesting they exploited different food niches. The results suggest coexisting ecotypes may possess innate differences in feeding and movement ecologies and may thus fill different functional roles in marine ecosystems. This highlights the importance of conserving interconnected populations to ensure stable ecosystem functioning and food web structures.
Collapse
Affiliation(s)
| | - Esben Moland Olsen
- Institute of Marine ResearchFlødevigen Marine Research StationHisNorway
- Centre for Coastal ResearchDepartment of Natural SciencesUniversity of AgderKristiansandNorway
| | - Even Moland
- Institute of Marine ResearchFlødevigen Marine Research StationHisNorway
- Centre for Coastal ResearchDepartment of Natural SciencesUniversity of AgderKristiansandNorway
| | - Halvor Knutsen
- Institute of Marine ResearchFlødevigen Marine Research StationHisNorway
- Centre for Coastal ResearchDepartment of Natural SciencesUniversity of AgderKristiansandNorway
| | - Peter Grønkjær
- Aquatic BiologyDepartment for BioscienceUniversity of AarhusAarhusDenmark
| | - Anders Koed
- National Institute for Aquatic ResourcesTechnical University of DenmarkSilkeborgDenmark
| | - Kristi Källo
- National Institute for Aquatic ResourcesTechnical University of DenmarkSilkeborgDenmark
| | - Kim Aarestrup
- National Institute for Aquatic ResourcesTechnical University of DenmarkSilkeborgDenmark
| |
Collapse
|