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  • 1
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 03 June 2014, Vol.111(22), pp.8083-8
    Description: Larval fishes suffer prodigious mortality rates, eliminating 99% of the brood within a few days after first feeding. Hjort (1914) famously attributed this "critical period" of low survival to the larvae's inability to obtain sufficient food [Hjort (1914) Rapp P-v Réun Cons Int Explor Mer 20:1-228]. However, the cause of this poor feeding success remains to be identified. Here, we show that hydrodynamic constraints on the ubiquitous suction mechanism in first-feeding larvae limit their ability to capture prey, thereby reducing their feeding rates. Dynamic-scaling experiments revealed that larval size is the primary determinant of feeding rate, independent of other ontogenetic effects. We conclude that first-feeding larvae experience "hydrodynamic starvation," in which low Reynolds numbers mechanistically limit their feeding performance even under high prey densities. Our results provide a hydrodynamic perspective on feeding of larval fishes that focuses on the physical properties of the larvae and prey, rather than on prey concentration and the rate of encounters.
    Keywords: Biomechanics ; Larval Ecology ; Stable Ocean Hypothesis ; Suction Feeding ; Hydrodynamics ; Feeding Behavior -- Physiology ; Sea Bream -- Growth & Development ; Starvation -- Mortality
    ISSN: 00278424
    E-ISSN: 1091-6490
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  • 2
    Language: English
    In: Proceedings. Biological sciences, 26 April 2017, Vol.284(1853)
    Description: Larval fishes experience extreme mortality rates, with 99% of a cohort perishing within days after starting to actively feed. While recent evidence suggests that hydrodynamic factors contribute to constraining larval feeding during early ontogeny, feeding is a complex process that involves numerous interacting behavioural and biomechanical components. How these components change throughout ontogeny and how they contribute to feeding remain unclear. Using 339 observations of larval feeding attempts, we quantified the effects of morphological and behavioural traits on feeding success of larvae during early ontogeny. Feeding success was determined using high-speed videography, under both natural and increased water viscosity treatments. Successful strikes were characterized by Reynolds numbers that were an order of magnitude higher than those of failed strikes. The pattern of increasing strike success with increasing age was driven by the ontogeny of traits that facilitate the transition to higher Reynolds numbers. Hence, the physical growth of a larva plays an important role in its transition to a hydrodynamic regime of higher Reynolds numbers, in which suction feeding is more effective.
    Keywords: Reynolds Number ; Kinematics ; Stable Ocean ; Suction Feeding ; Feeding Behavior ; Sea Bream -- Physiology
    ISSN: 09628452
    E-ISSN: 1471-2954
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  • 3
    Language: English
    In: Journal of Experimental Biology, June 1, 2016, Vol.219(11), p.1608(10)
    Description: Using videography to extract quantitative data on animal movement and kinematics constitutes a major tool in biomechanics and behavioral ecology. Advanced recording technologies now enable acquisition of long video sequences encompassing sparse and unpredictable events. Although such events may be ecologically important, analysis of sparse data can be extremely time-consuming and potentially biased; data quality is often strongly dependent on the training level of the observer and subject to contamination by observer-dependent biases. These constraints often limit our ability to study animal performance and fitness. Using long videos of foraging fish larvae, we provide a framework for the automated detection of prey acquisition strikes, a behavior that is infrequent yet critical for larval survival. We compared the performance of four video descriptors and their combinations against manually identified feeding events. For our data, the best single descriptor provided a classification accuracy of 77u95% and detection accuracy of 88u98%, depending on fish species and size. Using a combination of descriptors improved the accuracy of classification by ?2%, but did not improve detection accuracy. Our results indicate that the effort required by an expert to manually label videos can be greatly reduced to examining only the potential feeding detections in order to filter false detections. Thus, using automated descriptors reduces the amount of manual work needed to identify events of interest from weeks to hours, enabling the assembly of an unbiased large dataset of ecologically relevant behaviors.
    Keywords: Kinematics – Usage ; Animal Feeding Behavior – Research ; Animal Locomotion – Research ; Video Recordings – Usage
    ISSN: 0022-0949
    Source: Cengage Learning, Inc.
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  • 4
    Language: English
    In: The Journal of experimental biology, 01 June 2016, Vol.219(Pt 11), pp.1608-17
    Description: Using videography to extract quantitative data on animal movement and kinematics constitutes a major tool in biomechanics and behavioral ecology. Advanced recording technologies now enable acquisition of long video sequences encompassing sparse and unpredictable events. Although such events may be ecologically important, analysis of sparse data can be extremely time-consuming and potentially biased; data quality is often strongly dependent on the training level of the observer and subject to contamination by observer-dependent biases. These constraints often limit our ability to study animal performance and fitness. Using long videos of foraging fish larvae, we provide a framework for the automated detection of prey acquisition strikes, a behavior that is infrequent yet critical for larval survival. We compared the performance of four video descriptors and their combinations against manually identified feeding events. For our data, the best single descriptor provided a classification accuracy of 77-95% and detection accuracy of 88-98%, depending on fish species and size. Using a combination of descriptors improved the accuracy of classification by ∼2%, but did not improve detection accuracy. Our results indicate that the effort required by an expert to manually label videos can be greatly reduced to examining only the potential feeding detections in order to filter false detections. Thus, using automated descriptors reduces the amount of manual work needed to identify events of interest from weeks to hours, enabling the assembly of an unbiased large dataset of ecologically relevant behaviors.
    Keywords: Automated Classification ; Feeding Kinematics ; High-Speed Video ; Machine Learning ; Video Recording ; Feeding Behavior -- Physiology ; Fishes -- Physiology ; Statistics As Topic -- Methods
    ISSN: 00220949
    E-ISSN: 1477-9145
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  • 5
    Language: English
    In: Oecologia, August 2017, Vol.184(4), pp.859-871
    Description: Elucidating the factors determining reproductive success has challenged scientists since Darwin, but the exact pathways that shape the evolution of life history traits by connecting extrinsic (e.g., landscape structure) and intrinsic (e.g., female's age and endosymbionts) factors and reproductive success have rarely been studied. Here we collected female fleas from wild rodents in plots differing in their densities and proportions of the most dominant rodent species. We then combined path analysis and model selection approaches to explore the network of effects, ranging from micro to macroscales, determining the reproductive success of these fleas. Our results suggest that female reproductive success is directly and positively associated with their infection by Mycoplasma bacteria and their own body mass, and with the rodent species size and total density. In addition, we found evidence for indirect effects of rodent sex and rodent community diversity on female reproductive success. These results highlight the importance of exploring interrelated factors across organization scales while studying the reproductive success of wild organisms, and they have implications for the control of vector-borne diseases.
    Keywords: Fitness ; Life History ; Model Selection ; Parasites ; Path Analysis ; Scales ; Arthropod Vectors ; Flea Infestations ; Reproduction
    ISSN: 00298549
    E-ISSN: 1432-1939
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  • 6
    Keywords: Stable Ocean ; Kinematics ; Reynolds Number ; Suction Feeding ; Sparus Aurata
    ISSN: 0962-8452
    Source: DataCite
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  • 7
    In: Ecology, April 2009, Vol.90(4), pp.1134-1141
    Description: Sampling issues preclude the direct use of the discovery rate of exotic species as a robust estimate of their rate of introduction. Recently, a method was advanced that allows maximum‐likelihood estimation of both the observational probability and the introduction rate from the discovery record. Here, we propose an alternative approach that utilizes the discovery record of native species to control for sampling effort. Implemented in a Bayesian framework using Markov chain Monte Carlo simulations, the approach provides estimates of the rate of introduction of the exotic species, and of additional parameters such as the size of the species pool from which they are drawn. We illustrate the approach using Red Sea fishes recorded in the eastern Mediterranean, after crossing the Suez Canal, and show that the two approaches may lead to different conclusions. The analytical framework is highly flexible and could provide a basis for easy modification to other systems for which first‐sighting data on native and introduced species are available.
    Keywords: Colonization ; Coral Reef Fishes ; Hierarchical Bayes ; Invasion ; Nonindigenous Species ; State–Space Modeling
    ISSN: 0012-9658
    E-ISSN: 1939-9170
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  • 8
    In: Integrative and Comparative Biology, 2015, Vol. 55(1), pp.48-61
    Description: Larval fishes suffer prodigious mortality rates, eliminating 99% of the cohort within a few days after their first feeding. Hjort (1914) famously attributed this “critical period” of low survival to larval inability to obtain sufficient food. We discuss recent experimental and modeling work, suggesting that the viscous hydrodynamic regime have marked effects on the mechanism of suction feeding in larval fish. As larvae grow, the size of the gape and associated volume of the mouth increase. At the same time, larvae swim faster and can generate faster suction flows, thus transiting to a hydrodynamic regime of higher Reynolds numbers. This hydrodynamic regime further leads to changes in the spatio-temporal patterns of flow in front of the mouth, and an increasing ability in larger larvae to exert suction forces on the prey. Simultaneously, the increase in swimming speed and the distance from which the prey is attacked result in higher rates of encountering prey by larger (older) larvae. In contrast, during the first few days after feeding commence the lower rates of encounter and success in feeding translate to low feeding rates. We conclude that young larvae experience “hydrodynamic starvation,” in which low Reynolds numbers mechanically limit their feeding performance even under high densities of prey.
    Keywords: Zoology;
    ISSN: 1540-7063
    E-ISSN: 1557-7023
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  • 9
    Description: A representative movie of a “failed” feeding attempt of a 23 DPH Sparus aurata larvae obtained using our 3D system. movies shows the four synchronized views of the larvae....
    Keywords: Ecology ; Biomechanics
    Source: DataCite
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  • 10
    Description: A representative movie of a “failed” feeding attempt of a 23 DPH Sparus aurata larvae obtained using our 3D system. movies shows the four synchronized views of the larvae....
    Keywords: Ecology ; Biomechanics
    Source: DataCite
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