The significance of cephalopod beaks in marine ecology studies: Can we use beaks for DNA analyses and mercury contamination assessment?

Abstract

23Cephalopod beaks found in the diet of predators have been a major source of 24 scientific information. In this study, we evaluated the usefulness of DNA and 25 contaminants analysis (total mercury-T-Hg) in cephalopod beaks in order to assess their 26 applicability as tools in marine ecology studies. We concluded that, when applying DNA 27 techniques to cephalopod beaks from Antarctic squid species, when using flesh attached 28 to those beaks, it was possible to obtain DNA and to successfully identify cephalopod 29 species; DNA was not found on the beaks themselves. This study also showed that it is 30 possible to obtain information on T-Hg concentrations in beaks: the T-Hg concentrations 31 found in the beaks were 6 to 46 times lower than in the flesh of the same cephalopod 32 species. More research on the relationships of mercury concentrations in cephalopod 33 beaks (and other tissues), intra-and inter-specifically, are needed in the future. 34 35 CAPSULE ABSTRACT: DNA and contaminants analyses for the first time in 36 cephalopods beaks showed that flesh attached to beaks allows DNA species ID and beaks 37 had 6-46 times less total mercury than flesh. 38 39

Show your beaks and we tell you what you eat: Different ecology in sympatric Antarctic benthic octopods under a climate change context

“…On the other hand, A. polymorpha presented higher T-Hg concentrations regarding the lower beaks. Apparently, lower beaks also presented 6 to 10 times less T-Hg levels relative to muscle, similar values also found on several Antarctic squid species (Xavier et al, 2016). As mercury intake rates and elimination processes can vary between tissues and species (Penicaud et al, 2017;Seixas et al, 2005), any comparative ecological interpretations regarding habitat and trophic niches should be considered with caution.…”

“…All samples (A. polymorpha: n Lower = 10, n Muscle = 10; P. turqueti: n Lower = 10, n Muscle = 11) were lyophilised during 24 h and homogenized. T-Hg concentrations were determined by atomic absorption spectrometry, using an Advanced Mercury Analyzer (AMA) LECO 254, with thermal decomposition and gold amalgamation (Seco et al, 2019;Xavier et al, 2016). The detection limit of the equipment is 0.01 ng and the accuracy of the analysis was verified using mussel tissue (ERM -CE278K; 97 ± 16%) as certified reference material (CRM) for calculating recovery efficiency.…”

High cadmium and mercury concentrations in the tissues of the orange-back flying squid, Sthenoteuthis pteropus, from the tropical Eastern Atlantic

“…However, the correlation detected in this study will not necessarily hold when extrapolated to other populations or species. Further studies should also consider the concentrations of Hg in the beaks, being the tissue the most resistant to digestive processes of predators (Xavier et al 2016).…”

Antarctic octopod beaks as proxy for mercury concentrations in soft tissues

“…Within the Southern Ocean food webs, cephalopods are known to play important roles as both mid-trophic predator and prey for numerous top predators, including seabirds (Alvito et al, 2014;Casaux and Ramón, 2002;Cherel and Klages, 1998), marine mammals (Clarke, 1980;Negri et al, 2016;Rodhouse et al, 1992) and fish (Seco et al, 2016;Smales, 1996;Xavier et al, 2002). Since cephalopods are very elusive animals, researchers have still not fully addressed the existing gaps of knowledge regarding their ecology, including levels of contaminants such as Hg (Xavier et al, 2016). To overcome the hard challenge of collecting cephalopods using traditional sampling methods (e.g.…”

“…Only recently, researchers have been exploring the usage of beaks as a tool to evaluate Hg concentrations on cephalopods (Matias et al, 2019;Nguyen et al, 2018;Xavier et al, 2016). The reason for that is beaks are capable of absorbing and creating strong links with Hg due to its high specificity for amino groups present in proteins (Barriada et al, 2008), with Hg varying greatly as differences in beak pigmentation reflect different protein content (Miserez et al, 2008).…”