Apex marine predators and ocean health: Proactive screening of halogenated organic contaminants reveals ecosystem indicator species

Abstract

Despite decades-long bans on the production and use of certain chemicals, many halogenated organic compounds (HOCs) are persistent and can bioaccumulate in the marine environment with the potential to cause physiological harm to marine fauna. Highly lipid-rich tissue (e.g., marine mammal blubber) functions as a reservoir for HOCs, and selecting ideal indicator species is a priority for retrospective and proactive screening efforts. We selected five marine mammal species as possible indicators for the Southern California Bight (SCB) and applied a non-targeted analytical method paired with an automated data reduction strategy to catalog a broad range of known, known but unexpected, and unknown compounds in their blubber. A total of 194 HOCs were detected across the study species (n = 25 individuals), 81% of which are not routinely monitored, including 30 halogenated natural products and 45 compounds of unknown structure and origin. The cetacean species (long-beaked common dolphin, short-beaked common dolphin, and Risso's dolphin) averaged 128 HOCs, whereas pinnipeds (California sea lion and Pacific harbor seal) averaged 47 HOCs. We suspect this disparity can be attributed to differences in life history, foraging strategies, and/or enzyme-mediated metabolism. Our results support proposing (1) the long-and short-beaked common dolphin as apex marine predator sentinels for future and *

Non-targeted screening workflows for gas chromatography–high-resolution mass spectrometry analysis and identification of biomagnifying contaminants in biota samples

“…Several comprehensive studies on AHSs and HNPs have been conducted recently. Many have focused on dolphin species in warm water environments because dolphins are considered suitable top consumer species for biomonitoring and HNPs are abundant in such waters [ 36 ].…”

“…Two years later, Mackintosh et al [ 39 ] identified 45 bioaccumulative DDT-related compounds in blubber from the same species. In 2019, Cossaboon et al [ 36 ] reported a total of 194 halogenated contaminants in the blubber of five marine mammals (long-beaked common dolphin, short-beaked common dolphin, Risso’s dolphin, California sea lion, and Pacific harbor seal) from the Southern California Bight, including 30 HNPs. Most of the compounds (ca.…”

“…To further reduce the risk of coelution, comprehensive two-dimensional GC (GC×GC) could be used instead of GC. This technique has previously been used together with LRMS in similar studies [24,[36][37][38][39][40]43]. The combination of GC×GC and HRMS should provide outstanding separation power and facilitate identification of biomagnifying emerging contaminants.…”

“…In fact, we found no studies that combined GC-HRMS data acquisition with comprehensive NTS of hazardous substances in marine mammals. However, several NTS studies have used comprehensive twodimensional GC-electron ionization low-resolution MS (GC×GC-EI-LRMS) [36][37][38][39][40][41][42] or electron capture negative ion chemical ionization (ECNI) LRMS [43] to screen for anthropogenic and natural compounds in marine mammals. Furthermore, halogen-specific filters have been applied to HRMS data (excluding the GC dimension) to screen for organohalogens in striped dolphins from the Mediterranean Sea [44].…”

Novel use of pop-up satellite archival telemetry in sawsharks: insights into the movement of the common sawshark Pristiophorus cirratus (Pristiophoridae)

“…Many species perform critical roles in structuring biological communities through predation by exhibiting top-down controls thus allowing lower trophic levels to maintain viable diversity [10,11]. As such, the presence, abundance and health of such predators have been used as indicators of the overall health of ecosystems [10,12,13]. In addition, indirect effects of predators can be observed through prey response to the predators [14].…”