Human Consumption of Microplastics

Microplastics are ubiquitous across ecosystems, yet the exposure risk to humans is unresolved. Focusing on the American diet, we evaluated the number of microplastic particles in commonly consumed foods in relation to their recommended daily intake. The potential for microplastic inhalation and how the source of drinking water may affect microplastic consumption were also explored. Our analysis used 402 data points from 26 studies, which represents over 3600 processed samples. Evaluating approximately 15% of Americans’ caloric intake, we estimate that annual microplastics consumption ranges from 39000 to 52000 particles depending on age and sex. These estimates increase to 74000 and 121000 when inhalation is considered. Additionally, individuals who meet their recommended water intake through only bottled sources may be ingesting an additional 90000 microplastics annually, compared to 4000 microplastics for those who consume only tap water. These estimates are subject to large amounts of variation; however, given methodological and data limitations, these values are likely underestimates

Capture severity, infectious disease processes and sex influence post-release mortality of sockeye salmon bycatch

Bycatch is a common occurrence in heavily fished areas such as the Fraser River, British Columbia, where fisheries target returning adult Pacific salmon (Oncorhynchus spp.) en route to spawning grounds. The extent to which these encounters reduce fish survival through injury and physiological impairment depends on multiple factors including capture severity, river temperature and infectious agents. In an effort to characterize the mechanisms of post-release mortality and address fishery and managerial concerns regarding specific regulations, wild-caught Early Stuart sockeye salmon (Oncorhynchus nerka) were exposed to either mild (20 s) or severe (20 min) gillnet entanglement and then held at ecologically relevant temperatures throughout their period of river migration (mid-late July) and spawning (early August). Individuals were biopsy sampled immediately after entanglement and at death to measure indicators of stress and immunity, and the infection intensity of 44 potential pathogens. Biopsy alone increased mortality (males: 33%, females: 60%) when compared with nonbiopsied controls (males: 7%, females: 15%), indicating high sensitivity to any handling during river migration, especially among females. Mortality did not occur until 5-10 days after entanglement, with severe entanglement resulting in the greatest mortality (males: 62%, females: 90%), followed by mild entanglement (males: 44%, females: 70%). Infection intensities of Flavobacterium psychrophilum and Ceratonova shasta measured at death were greater in fish that died sooner. Physiological indicators of host stress and immunity also differed depending on longevity, and indicated anaerobic metabolism, osmoregulatory failure and altered immune gene regulation in premature mortalities. Together, these results implicate latent effects of entanglement, especially among females, resulting in mortality days or weeks after release. Although any entanglement is potentially detrimental, reducing entanglement durations can improve post-release survival

Paleoclimate Shaped Bluefish Structure in the Northern Hemisphere

<div><p>ABSTRACT</p><p>Bluefish (<i>Pomatomus saltatrix</i>), a highly migratory cosmopolitan predator, is the only extant representative of the family Pomatomidae. It has been the subject of many studies due to its commercial and recreational value, but much less research has been conducted on its global population structure. Here we investigate the population structure of this species and the effects of present and past oceanographic barriers to dispersal in its North Atlantic, Mediterranean, Marmara, and Black sea populations. We employed mitochondrial (cytochrome b and cytochrome oxidase subunit I genes) and nuclear (eight microsatellite loci) DNA as molecular markers. Three main genetic units of Bluefish were identified: American (West Atlantic waters), Spanish (East Atlantic–Western Mediterranean regions), and Turkish (Eastern Mediterranean, Marmara, and Black seas). Our results suggested that Bluefish is panmictic in the northwest Atlantic Ocean but not in the Mediterranean Sea. The common ancestor of the studied populations was traced back to the interglacial cycle Aftonian II, and the separation between clades was estimated to have occurred during glacial periods, likely due to migrations to refuges and the closure of the Mediterranean Sea. In conclusion, paleoclimate seems to have been fundamental for shaping the present genetic lineages of <i>Pomatomus saltatrix</i>.</p></div

Mislabeling of Two Commercial North American Hake Species Suggests Underreported Exploitation of Offshore Hake

Mislabeling of North American merlucciid hakes in stock surveys and commercial market samples was detected by employing nuclear 5S ribosomal DNA (rDNA) and mitochondrial cytochrome b variation as molecular markers. Results showed that offshore hake Merluccius albidus is sold in European markets but is labeled as the morphologically similar silver hake M. bilinearis, which is the target species of the fishery. This suggests that offshore hake may be inadvertently included within silver hake landings, as the two species overlap in the southern area of silver hake distribution (approximately 41°-35°N latitude near North American coasts). An inexpensive and technically easy technique based on polymerase chain reaction (PCR) amplification of a fragment of 5S rDNA and visualization of PCR products in agarose gels is recommended for routine species assignation in landings for purposes of exploitation estimates and for authentication of commercial hake species

Soniferous fishes in the Hudson River

Although soniferous fishes have been studied in many different parts of the world, very few studies have been conducted in North American freshwater systems. The purpose of this study was to catalog and identify types of underwater sounds in the Hudson River, New York. We recorded underwater sounds with an autonomous underwater listening system consisting of a hydrophone, digital sound recorder, and weatherproof housing. Approximately 164 h of recordings were made from two sites located along the Hudson River during 2003. One site was located near the mouth of the river on Manhattan Island. The second site was located 153 km upriver within Tivoli Bays at the Hudson River National Estuarine Research Reserve. Additional manned recordings and sound auditioning of captured fishes were conducted in 2004 to identify biological and unknown sounds from Tivoli Bays. In all, we recorded 62 different sounds. Only four sounds could be identified to fish species: Oyster toadfish Opsanus tau, striped cusk-eel Ophidion marginatum, brown bullhead Ameiurus nebulosus, and channel catfish Ictalurus punctatus. An additional 21 sounds were categorized as biological, 5 as nonbiological, and 32 as unknown. We believe that many of the sounds classified as biological and unknown are in fact produced by fishes but could not be identified due to the scarcity of studies on the sound production of freshwater and estuarine fishes of the Hudson River. Future research focused on the identification of these unknown underwater sounds will provide new insights into the ecology of the Hudson River. The diversity of underwater sounds we recorded in the Hudson River strongly suggests that sound production is an important behavior in aquatic systems and that passive acoustics can be an important new tool for the study of the river\u27s ecology