Effects of sample cleaning and storage on the elemental composition of shark vertebrae

Mohan, John A.; TinHan, Thomas C.; Miller, Nathaniel R.; Wells, R. J. David

doi:10.1002/rcm.7998

Cited by 7 publications

(7 citation statements)

References 31 publications

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“…Following common protocols (Cailliet & Goldman, 2004), the centrum of each vertebra was cleaned by removing the neural arch and any adherent soft tissues mechanically. When necessary, chemical cleaning by soaking the vertebra in 5% sodium hypochlorite for 5 min was used to remove residual tissues, as it does not affect the vertebra composition (Mohan et al ., 2017). The vertebrae were then rinsed in a bath of distilled water for 10 min and cut in the middle (sections of c .…”

Section: Methodsmentioning

confidence: 99%

Age and growth of the bull shark (Carcharhinus leucas) around Reunion Island, South West Indian Ocean

Hoarau

Darnaude

Poirout

et al. 2021

Journal of Fish Biology

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Sharks exhibit varied demographic strategies depending on both the species and the population location, which make them more or less vulnerable to fishing. Accurate evaluation of local age and growth parameters is therefore fundamental for the sustainable management of their stocks. Although demographic parameters have been assessed for bull shark (Carcharhinus leucas) populations in several locations of the world, this information is missing so far around Reunion Island, in the south‐west Indian Ocean. To fill this gap of knowledge, age and growth data were gathered from the vertebrae of 140 individuals of C. leucas (77 females and 63 males, mostly adults) fished around the island between 2012 and 2019. After verification of the annual deposition of growth band pairs on these structures using relative marginal increment analysis on 40 individuals, band pairs were counted along the vertebral centrum for each individual. Thanks to this approach, growth was shown to significantly differ between male and female C. leucas around Reunion Island, with respective von Bertalanffy growth model equations of Lt = 314()1−e−0.0814()t+5.45 and Lt = 321.5()1−e−0.0999()t+3.420. Indeed, the females of the species fished in this area were significantly (P < 0.001) larger than local males, with an estimated difference in size of ~16.1 cm at 20 years old. They also apparently reach older ages, with an estimated maximum age of 33.50 years, against 29.75 years only for the males. The estimated size at birth around the island is larger than elsewhere in the world, varying from 92.30 to 100.00 cm depending on the method used. These results confirm that the population of C. leucas around Reunion Island exhibits a K‐selected strategy, which makes it highly vulnerable to fishing pressure.

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Section: Methodsmentioning

confidence: 99%

Age and growth of the bull shark (Carcharhinus leucas) around Reunion Island, South West Indian Ocean

Hoarau

Darnaude

Poirout

et al. 2021

Journal of Fish Biology

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“…Vertebrae centra were either stored dry, frozen or in ethanol, as previous experiments have demonstrated minimal influence of these storage methods on primary elemental composition [ 36 ]. Vertebrae centra were cut using a low-speed diamond blade saw along central longitudinal planes to obtain approximately 2 mm thick central ‘bowtie’ sections.…”

Section: Methodsmentioning

confidence: 99%

“…R. Soc. B 285: 20181760 these storage methods on primary elemental composition [36]. Vertebrae centra were cut using a low-speed diamond blade saw along central longitudinal planes to obtain approximately 2 mm thick central 'bowtie' sections.…”

Section: (B) Vertebrae Preparation and Analysismentioning

confidence: 99%

Elements of time and place: manganese and barium in shark vertebrae reflect age and upwelling histories

et al. 2018

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As upper-level predators, sharks are important for maintaining marine food web structure, but populations are threatened by fishery exploitation. Sustainable management of shark populations requires improved understanding of migration patterns and population demographics, which has traditionally been sought through physical and/or electronic tagging studies. The application of natural tags such as elemental variations in mineralized band pairs of elasmobranch vertebrae cartilage could also reveal endogenous and exogenous processes experienced by sharks throughout their life histories. Here, elemental profiles were characterized in vertebrae encompassing complete life histories (birth-to-death) of shortfin mako (Isurus oxyrinchus), common thresher (Alopias vulpinus) and blue shark (Prionace glauca) of known tag and recapture locations in the eastern North Pacific Ocean. All sharks were injected with oxytetracycline at initial capture, released and subsequently recaptured, with individual liberty times ranging from 215 days to 6 years. Vertebral band pairs forming over the liberty intervals were verified by counting the number of band pairs deposited since the oxytetracycline band. Regular oscillations in vertebrae manganese (Mn) content corresponded well with the number of validated band pairs, suggesting that Mn variation could be used to age sharks. Increases in vertebrae barium concentration were correlated with times when individuals occupied areas with high coastal upwelling indices, the timing and spatial intensity of which varied from year to year. Interspecific relationships were probably influenced by behavioural differences in horizontal and vertical habitat use, feeding habits and thermoregulatory physiology. These results indicate that vertebral sclerochronology has the potential to advance our knowledge of elasmobranch life history including age and growth estimation and environmental reconstruction.

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“…Samples collected by R. Lessa and V. Batista in the 1980s were also included in the analysis (n = 8) (see Lessa and Santana, 1998 for sampling locations). Although these were subjected to formaldehyde 4% treatment, it does not impair our analysis since there is no evidence of this kind of procedure affecting microchemistry results -other than sodium concentration (Mohan et al, 2017). Furthermore, although we acknowledge that the sample size used was somewhat small, other studies using trace elements for habitat use, and even age and growth analysis, used smaller sample sizes for critically endangered, vulnerable, and near threatened shark and teleost species, including with a single hard part sample (Scharer et al, 2012;Hermann et al, 2016;Mohan et al, 2018).…”

Section: Sampling Designmentioning

confidence: 99%

Habitat Use Patterns and Identification of Essential Habitat for an Endangered Coastal Shark With Vertebrae Microchemistry: The Case Study of Carcharhinus porosus

2020

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Sharks are among the most endangered and data poor vertebrates in the world. The lack of information regarding their habitat use is especially concerning since these are crucial for the establishment of priority areas for species conservation. Investigating the trace elements present in shark vertebrae has become an interesting tool to analyze species habitat use over individuals' lifetimes. Therefore, we applied vertebrae microchemistry to investigate habitat use of Carcharhinus porosus in Brazil's Northern Coast (BNC). We also discuss methodological issues that must be addressed in the future to make microchemistry studies with elasmobranchs at low latitudes more robust. Vertebrae from seventeen individuals sampled in the 1980s (n = 8), and in 2017 and 2018 (n = 9) were evaluated through laser ablation inductively coupled plasma mass spectrometry. We analyzed five elements known to reflect environmental characteristics (Ba, Ca, Mg, Mn, and Sr) by sex, seasons, decades of capture, and life stages. Since Ca is the most abundant element in the vertebrae, we calculated element:Ca ratios and employed these proportions for all statistical analysis. We also used fisheriesindependent catch data from the 1980s to test if the BNC is a nursery area for C. porosus. We found significant differences in element concentrations between sexes in both multi and single-element analysis, while decades differed only in the multi-element and Sr:Ca. Furthermore, seasons differed in both multi-element and Mg:Ca and Ba:Ca ratios. We did not find differences between life stages. Neonate multi-element signatures yielded three major groups, thus suggesting that the species has at least three birthing grounds in the area. Despite the occurrence of individuals of all sizes, adults show a more distinct occurrence pattern. Our results point toward the hypothesis that the BNC is an essential habitat for this species since its whole life cycle occurs in this area. Therefore, the BNC is a critical area for its conservation. We reinforce that future studies with strictly tropical species should investigate the effects of metabolism, the species' growth rate, and the validation of other elements capable of demonstrating fine-scale changes in habitat to reduce the inherent noise in microchemistry studies.

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Effects of sample cleaning and storage on the elemental composition of shark vertebrae

Cited by 7 publications

References 31 publications

Age and growth of the bull shark (Carcharhinus leucas) around Reunion Island, South West Indian Ocean

Age and growth of the bull shark (Carcharhinus leucas) around Reunion Island, South West Indian Ocean

Elements of time and place: manganese and barium in shark vertebrae reflect age and upwelling histories

Habitat Use Patterns and Identification of Essential Habitat for an Endangered Coastal Shark With Vertebrae Microchemistry: The Case Study of Carcharhinus porosus

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