Sharkpedia Meghan Holst and Amani Webber-Schultz

Did you know that shark body form can change as they grow? Why does that happen? Why does it matter? Find out this week on our episode investigating these questions of bull sharks with Joel Gayford!


Title: Ontogenetic Shifts in body form in the bull shark Carcharhinus leucas


Summary: It is believed that body growth is strongly correlated to trophic and spatial ecology through ontogeny, or as a shark ages. Gayford et al. used bull sharks as their study species to better understand morphological growth at many different locations along a shark's body. They found shifts in functional demands across the body through ontogeny, seemingly driven by selective pressures relating to trophic and spatial ecology. They also found significant differences in scaling trends between life stages and sexes. They ultimately discuss the implications of their results for existing ecomorphological hypotheses and provide a robust study to add to much needed research in this area.

You can follow Joel Gayford @sharkmeasurements on instagram



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Juvenile shark presence in an area does NOT mean that that area is a shark pupping or nursery ground. So how do we know what actually makes a shark nursery ground? What even IS a nursery ground? Is it different than a pupping ground? Why does any of this matter? Find out this week with our special guest, Dr. Michelle Heupel!



Dr. Heupel joins us to talk about her article, "Shark nursery areas: concepts, definition, characterization and assumptions" (Heupel et al. 2007).



Article Summary:

Shark nursery habitats are critical areas that sharks rely on for their early life stages. However, the criteria defining shark nursery grounds has been inconsistent through history. These inconsistencies can make management strategies more difficult, as some definitions could imply that all coastal areas are nursery habitats, and other definitions are insufficient. In this study, Heupel et al. propose a new definition for shark nursery habitats that will more accurately pinpoint Essential Fish Habitat. That definition is: (1) sharks are more commonly encountered in the area than other areas; (2) sharks have a tendency to remain or return for extended periods; and (3) the area or habitat is repeatedly used across years. These criteria make the definition of shark nursery areas more compatible with those for other aquatic species. The improved definition of this concept will provide more valuable information for fisheries managers and shark biologists.



You can follow Dr. Heupel @michelleheupel on instagram, and follow her work on Research Gate and Google Scholar!



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This week Amani and Meghan discuss sand tiger sharks from the Eocene with Dr. Sora Kim! We explore the ecology and environment of sand tiger sharks during the Eocene, and can even explore climate change during the Eocene using sand tiger teeth fossils! This discussion was guided around Dr. Sora Kim's publication, "Probing the Ecology and Climate of the Eocene Southern Ocean With Sand Tiger Sharks Striatolamia macrota". Get ready to learn about some incredible things we can learn about the climate during the Eocene using stable isotope analysis of teeth from extinct sand tiger sharks! 
You can connect with Dr. Sora Kim on Twitter @SoraLKim
This episode was edited by Kaela Shoe
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This week we jump into stress physiology with expert and PhD Candidate Alex Schoen! With Alex's help, we breakdown her article, "Simulated heatwave and fishing stressors alter corticosteroid and energy balance in neonate blacktip reef shark, Carcharhinus melanopterus" (Schoen et al. 2021). With climate change as an increasing temperature stressor on marine life, and human-influenced impacts such as fishing, it's important we understand how sharks withstand and process this stress to evaluate if they can survive. Get ready to jump into a world of shark stress physiology!
You can follow Alex on Twitter @Science_Schoen
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This week we had a very fun time talking with Dr. Taylor Chapple about maximizing datasets with video biologgers that are attached to sharks! Are you listening to the podcast and wondering who Dr. Alex McInturf is? Listen to our very first interview episode in Season 1!



We chat with Dr. Chapple about his article, Ancillary data from animal-borne cameras as an ecological survey tool for marine communities



Article Summary: Underwater visual surveys, such as diver-based video surveys, are a common and essential technique in measuring and managing marine ecosystems. However, there are several limitations to doing such surveys, such as recreational diving depth limitations, or animal interactions that preclude safe diving (such as White shark - sea lion interactions). Biologging camera tag devices are commonly used to study a single, focal species' behavior. However, ecosystem-wide data is collected and could be used to monitor and assess habitats that may not be accessible to humans. In this study, Chapple et al. use a video camera logger on a White shark off Gansbaai, South Africa, and a Grey Reef shark within the Chagos Archipelago, to determine if video logging could be used to measure the habitat structure of their respective environments. They used established methods to analyze video data and found that the biologging from the sharks was relatively comparable. Using biologgers such as the ones used in this study could maximize the overall cost and effort of tagging deployments by gathering more ecosystem-wide data, than just the focal species data.







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This week we talk with Dr. Haley Dolton about how she studied the physiology of basking sharks in Ireland! This is no small feat.



We read Dr. Dolton's article, "Regional endothermic traits in planktivorous basking sharks Cetohinus maximus"



Article Summary: The majority of sharks are classified as cold-blooded or ectotherms. Sharks are constantly battling heat loss to the surrounding water. To combat this, some fast-swimming apex species are classified as regional endotherms, having uncommon physiological traits such as elevated internal body temperatures, centralized red muscle, and thick-walled hearts. Within the order Lamniformes, housing the only regionally endothermic sharks, you can find the basking shark which is a large, filter-feeding planktivorous species. Previous research has led to the conclusion that basking sharks are ectothermic. To investigate this, Dolton et al. collected muscle samples and measured the internal temperature of basking sharks finding that they displayed the traits previously stated. Their research leads to the finding that basking sharks may not be correctly classified as an ectotherm, which is a surprising find!

You can follow Dr. Dolton @HaleyDolton on Instagram and Twitter!



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