Reliance of young sharks on threatened estuarine habitats for nutrition implies susceptibility to climate change

Ontogenetic changes in the tooth morphology of bull sharks (Carcharhinus leucas)

“…Niella et al . ( 2021 , 2022 ) found significant ontogenetic shifts in niche use within the Clarence River nursery area. A gradual shift in δ 13 C indicated sharks <130 cm L T prefer less saline environments upstream, while larger sharks inhabit increasingly more saline environments.…”

“…To determine whether our identification of an ontogenetic change in tooth shape, surface area and thickness at ~135 cm L T is related to changes in prey and a potential niche shift, we compared our results with those of Niella et al . ( 2021 , 2022 ), who conducted a stable isotope analysis on the same sample of juvenile C . leucas .…”

“…There were significant inflection points in δ 15 N and δ 34 S (Niella et al ., 2021 ), indicating juvenile C . leucas moved towards the river mouth and relied on different habitats for food (Niella et al ., 2022 ). These findings are consistent with our findings of ontogenetic changes in tooth morphology at similar size/age, indicating a niche shift of C .…”

One marine protected area is not enough: The trophic ecology of the broadnose sevengill shark (Notorynchus cepedianus) in the Southwest Atlantic

“…Investigating feeding habits and habitat use is crucial for understanding specieshabitat relationships in the face of climate change (Birkmanis et al, 2020;Niella et al, 2022).…”

Updates on putative bull shark (Carcharhinus leucas) occurrences in the upper Mississippi River Basin of North America

“…While the behavior of bull sharks in estuarine and riverine environments has been the subject of previous studies (Heupel and Simpfendorfer 2008;Ortega et al 2009;Heupel et al 2010;Curtis et al 2011;Curtis et al 2013), it is important to continue to monitor for behavioral changes associated with climate change for which temperature increases and sea level rises are predicted to alter or increase the frequency in which bull sharks may utilize these near-coastal brackish to freshwater environments (Heithaus et al 2009;Matich et al 2020). Recent studies have already demonstrated that given their reliance on these ecosystems as nurseries, bull sharks are susceptible to climate change-driven alterations of estuaries (Niella et al 2022). There is already evidence for these behavioral shifts in the global fossil record of bull sharks dating back at least as far as the Pleistocene (Lopes et al 2020) and opportunistic exploration by bull sharks into man-made waterways are well documented worldwide (Alive... 1896;Montoya and Thorson 1982;Werry et al 2012;Curtis et al 2013).…”