Papers by Joseph Bizzarro
Marine Pollution Bulletin
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PLOS ONE
The yellowtail rockfish, Sebastes flavidus, is a widespread and abundant mesopredator in the Cali... more The yellowtail rockfish, Sebastes flavidus, is a widespread and abundant mesopredator in the California Current Large Marine Ecosystem. We utilized stomach content and stable isotope analyses to investigate the trophic ecology of this species at three sites off central California just before (August–October 2013) and during (August and October 2014) a marine heat wave. Sebastes flavidus largely consumed pelagic prey (zooplankton and micronekton). Diets were dominated by tunicates (salps and pyrosomes), pelagic crustaceans (euphausiids, hyperid amphipods, larval decapods), and fishes, with the relative contribution of these prey taxa varying spatially (sample location, longitude, depth) and temporally (year, month), based on complementary multivariate analyses. Prey-specific indices demonstrated that individual S. flavidus diet composition typically was dominated by one of these prey groups, and that prey switching occurred based on the relative availability of prey and their energet...
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Advances in Marine Biology
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Bone
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Fishery Bulletin
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Acta Biomaterialia
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Biological Conservation
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Advances in marine biology, 2017
Although there is a general perception of sharks as large pelagic, apex predators, most sharks ar... more Although there is a general perception of sharks as large pelagic, apex predators, most sharks are smaller, meso- and upper-trophic level predators that are associated with the seafloor. Among 73 shark species documented in the eastern North Pacific (ENP), less than half reach maximum lengths >200cm, and 78% occur in demersal or benthic regions of the continental shelf or slope. Most small (≤200cm) species (e.g., houndsharks) and demersal, nearshore juveniles of larger species (e.g., requiem sharks) consume small teleosts and decapod crustaceans, whereas large species in pelagic coastal and oceanic environments feed on large teleosts and squids. Several large, pelagic apex predator species occur in the ENP, but the largest species (i.e., Basking Shark, Whale Shark) consume zooplankton or small nekton. Size-based dietary variability is substantial for many species, and segregation of juvenile and adult foraging habitats also is common (e.g., Horn Shark, Shortfin Mako). Temporal di...
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Royal Society Open Science
The shapes of vertebrate teeth are often used as hallmarks of diet. Here, however, we demonstrate... more The shapes of vertebrate teeth are often used as hallmarks of diet. Here, however, we demonstrate evidence of frequent piscivory by cartilaginous fishes with pebble-like teeth that are typically associated with durophagy, the eating of hard-shelled prey. High-resolution micro-computed tomography observation of a jaw specimen from one batoid species and visual investigation of those of two additional species reveal large numbers of embedded stingray spines, arguing that stingray predation of a scale rivalling that of the largest carnivorous sharks may not be uncommon for large, predatory batoids with rounded, non-cutting dentition. Our observations demonstrate that tooth morphology is not always a reliable indicator of diet and that stingray spines are not as potent a deterrent to predation as normally believed. In addition, we show that several spines in close contact with the jaw skeleton of a wedgefish ( Rhynchobatus ) have become encased in a disorganized mineralized tissue with ...
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Marine Biology
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Ciencias Marinas
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Environmental Biology of Fishes, 2016
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Canadian Journal of Fisheries and Aquatic Sciences, 2016
Stable isotope analysis (SIA) is becoming a commonly used tool to study the ecology of elasmobran... more Stable isotope analysis (SIA) is becoming a commonly used tool to study the ecology of elasmobranchs. However, the retention of urea by elasmobranchs for osmoregulatory purposes may bias the analysis and interpretation of SIA data. We examined the effects of removing urea and lipid on the stable isotope composition of 14 species of sharks, skates, and rays from the eastern North Pacific Ocean. While effects were variable across taxa, removal of urea generally increased δ15N and C:N. Urea removal had less influence on δ13C, whereas extracting urea and lipid generally increased δ15N, C:N, and δ13C. Because C:N values of nonextracted tissues are often used to infer lipid content and adjust δ13C, shifts in C:N following urea extraction will change the inferred lipid content and bias any mathematical adjustment of δ13C. These results highlight the importance of urea and lipid extraction and demonstrate the confounding effects of these compounds, making it impossible to use C:N of non-ure...
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Fishery Bulletin, 2016
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Ciencias Marinas, Jun 1, 2009
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Page 1. EL ESTADO ACTUAL DE LOS TIBURONES Y RAYAS SUJETOS A EXPLOTACIÓN COMERCIAL EN EL GOLFO DE ... more Page 1. EL ESTADO ACTUAL DE LOS TIBURONES Y RAYAS SUJETOS A EXPLOTACIÓN COMERCIAL EN EL GOLFO DE CALIFORNIA: UNA INVESTIGACIÓN APLICADA AL MEJORAMIENTO DE SU MANEJO PESQUERO Y CONSERVACIÓN ...
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Environmental Biology of Fishes, Feb 14, 2007
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The Gulf of California supports a rich elasmobranch fauna, with more than 85 documented species. ... more The Gulf of California supports a rich elasmobranch fauna, with more than 85 documented species. However, environmental alteration (e.g., damming of the Colorado River, marine pollution, coastal development) and years of unregulated fishery exploitation have resulted in substantial changes to the marine fauna of this region, including considerable declines in populations of several elasmobranch species. Apparent changes in elasmobranch faunal composition will be treated qualitatively (based on a synthesis of available information) because detailed historic records are not available. An updated list of all documented elasmobranch species will be provided, and single occurrences and recent absences will be discussed. Patterns of taxonomic diversity will be compared to those of other comparable subtropical regions. In addition, trends in species composition and diversity of demersal, nearshore elasmobranchs will be quantitatively assessed based on the results of comprehensive, year-rou...
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Papers by Joseph Bizzarro