scholarly journals Evidence that Pacific tuna mercury levels are driven by marine methylmercury production and anthropogenic inputs

2022 ◽  
Vol 119 (2) ◽  
pp. e2113032119
Author(s):  
Anaïs Médieu ◽  
David Point ◽  
Takaaki Itai ◽  
Hélène Angot ◽  
Pearse J. Buchanan ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Generalized Additive Models ◽  
Oxygen Depletion ◽  
Atmospheric Mercury ◽  
Additive Models ◽  
Spatial Gradient ◽  
Low Oxygen ◽  
Central Pacific ◽  
The Pacific ◽  
The Pacific Ocean

Pacific Ocean tuna is among the most-consumed seafood products but contains relatively high levels of the neurotoxin methylmercury. Limited observations suggest tuna mercury levels vary in space and time, yet the drivers are not well understood. Here, we map mercury concentrations in skipjack tuna across the Pacific Ocean and build generalized additive models to quantify the anthropogenic, ecological, and biogeochemical drivers. Skipjack mercury levels display a fivefold spatial gradient, with maximum concentrations in the northwest near Asia, intermediate values in the east, and the lowest levels in the west, southwest, and central Pacific. Large spatial differences can be explained by the depth of the seawater methylmercury peak near low-oxygen zones, leading to enhanced tuna mercury concentrations in regions where oxygen depletion is shallow. Despite this natural biogeochemical control, the mercury hotspot in tuna caught near Asia is explained by elevated atmospheric mercury concentrations and/or mercury river inputs to the coastal shelf. While we cannot ignore the legacy mercury contribution from other regions to the Pacific Ocean (e.g., North America and Europe), our results suggest that recent anthropogenic mercury release, which is currently largest in Asia, contributes directly to present-day human mercury exposure.

scholarly journals Biogeochemistry of the North Atlantic during oceanic anoxic event 2: role of changes in ocean circulation and phosphorus input

2014 ◽  
Vol 11 (4) ◽  
pp. 977-993 ◽  
Author(s):  
I. Ruvalcaba Baroni ◽  
R. P. M. Topper ◽  
N. A. G. M. van Helmond ◽  
H. Brinkhuis ◽  
C. P. Slomp
Keyword(s):  
Pacific Ocean ◽  
Ocean Circulation ◽  
North Atlantic ◽  
Primary Productivity ◽  
Low Oxygen ◽  
Deep Basin ◽  
The North ◽  
The Pacific ◽  
The Pacific Ocean ◽  
The North Atlantic

Abstract. The geological record provides evidence for the periodic occurrence of water column anoxia and formation of organic-rich deposits in the North Atlantic Ocean during the mid-Cretaceous (hereafter called the proto-North Atlantic). Both changes in primary productivity and oceanic circulation likely played a role in the development of the low-oxygen conditions. Several studies suggest that an increased input of phosphorus from land initiated oceanic anoxic events (OAEs). Other proposed mechanisms invoke a vigorous upwelling system and an ocean circulation pattern that acted as a trap for nutrients from the Pacific Ocean. Here, we use a detailed biogeochemical box model for the proto-North Atlantic to analyse under what conditions anoxia could have developed during OAE2 (94 Ma). The model explicitly describes the coupled water, carbon, oxygen and phosphorus cycles for the deep basin and continental shelves. In our simulations, we assume the vigorous water circulation from a recent regional ocean model study. Our model results for pre-OAE2 and OAE2 conditions are compared to sediment records of organic carbon and proxies for photic zone euxinia and bottom water redox conditions (e.g. isorenieratane, carbon/phosphorus ratios). Our results show that a strongly elevated input of phosphorus from rivers and the Pacific Ocean relative to pre-OAE2 conditions is a requirement for the widespread development of low oxygen in the proto-North Atlantic during OAE2. Moreover, anoxia in the proto-North Atlantic is shown to be greatly influenced by the oxygen concentration of Pacific bottom waters. In our model, primary productivity increased significantly upon the transition from pre-OAE2 to OAE2 conditions. Our model captures the regional trends in anoxia as deduced from observations, with euxinia spreading to the northern and eastern shelves but with the most intense euxinia occurring along the southern coast. However, anoxia in the central deep basin is difficult to achieve in the model. This suggests that the ocean circulation used in the model may be too vigorous and/or that anoxia in the proto-North Atlantic was less widespread than previously thought.

scholarly journals Using Microwave Satellite Data to Assess Changes in Storminess over the Pacific Ocean

2015 ◽  
Vol 143 (8) ◽  
pp. 3214-3229 ◽  
Author(s):  
Michael C. Kruk ◽  
Kyle Hilburn ◽  
John J. Marra
Keyword(s):  
Wind Speed ◽  
Pacific Ocean ◽  
Rain Rate ◽  
The United States ◽  
The Philippines ◽  
Tropical Pacific ◽  
Central Pacific ◽  
The Pacific ◽  
The Pacific Ocean ◽  
Increasing Trends

Abstract This study analyzes 25 years of Special Sensor Microwave Imager (SSM/I) retrievals of rain rate and wind speed to assess changes in storminess over the open water of the Pacific Ocean. Changes in storminess are characterized by combining trends in both the statistically derived 95th percentile exceedance frequencies of rain rate and wind speed (i.e., extremes). Storminess is computed annually and seasonally, with further partitioning done by phase of the El Niño–Southern Oscillation (ENSO) index and the Pacific decadal oscillation (PDO) index. Overall, rain-rate exceedance frequencies of 6–8 mm h−1 cover most of the western and central tropical Pacific, with higher values present around the Philippines, Japan, Mexico, and the northwest coast of Australia. Wind speed exceedance frequencies are a strong function of latitude, with values less (greater) than 12 m s−1 equatorward (poleward) of 30°N/S. Statistically significant increasing trends in rain rate were found in the western tropical Pacific near the Caroline Islands and the Solomon Islands, and in the extratropics from the Aleutian Islands down the coast along British Columbia and Washington State. Statistically significant increasing trends in wind speed are present in the equatorial central Pacific near Kiribati and the Republic of the Marshall Islands (RMI), and in the extratropics along the west coast of the United States and Canada. Thus, while extreme rain and winds are both increasing across large areas of the Pacific, these areas are modulated according to the phase of ENSO and the PDO, and their intersection takes aim at specific locations.

scholarly journals Extreme endurance flights by landbirds crossing the Pacific Ocean: ecological corridor rather than barrier?

2008 ◽  
Vol 276 (1656) ◽  
pp. 447-457 ◽  
Author(s):  
Robert E Gill ◽  
T. Lee Tibbitts ◽  
David C Douglas ◽  
Colleen M Handel ◽  
Daniel M Mulcahy ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Satellite Telemetry ◽  
Survival Rates ◽  
Phenotypic Flexibility ◽  
Migration Routes ◽  
Central Pacific ◽  
Flight Duration ◽  
Ecological Corridor ◽  
The Pacific ◽  
The Pacific Ocean

Mountain ranges, deserts, ice fields and oceans generally act as barriers to the movement of land-dependent animals, often profoundly shaping migration routes. We used satellite telemetry to track the southward flights of bar-tailed godwits ( Limosa lapponica baueri ), shorebirds whose breeding and non-breeding areas are separated by the vast central Pacific Ocean. Seven females with surgically implanted transmitters flew non-stop 8117–11 680 km (10 153±1043 s.d.) directly across the Pacific Ocean; two males with external transmitters flew non-stop along the same corridor for 7008–7390 km. Flight duration ranged from 6.0 to 9.4 days (7.8±1.3 s.d.) for birds with implants and 5.0 to 6.6 days for birds with externally attached transmitters. These extraordinary non-stop flights establish new extremes for avian flight performance, have profound implications for understanding the physiological capabilities of vertebrates and how birds navigate, and challenge current physiological paradigms on topics such as sleep, dehydration and phenotypic flexibility. Predicted changes in climatic systems may affect survival rates if weather conditions at their departure hub or along the migration corridor should change. We propose that this transoceanic route may function as an ecological corridor rather than a barrier, providing a wind-assisted passage relatively free of pathogens and predators.

scholarly journals Predicting bycatch hotspots for endangered leatherback turtles on longlines in the Pacific Ocean

2014 ◽  
Vol 281 (1777) ◽  
pp. 20132559 ◽  
Author(s):  
John H. Roe ◽  
Stephen J. Morreale ◽  
Frank V. Paladino ◽  
George L. Shillinger ◽  
Scott R. Benson ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Pacific Islands ◽  
Fishing Effort ◽  
Western Pacific ◽  
Central Pacific ◽  
Leatherback Turtles ◽  
The Pacific ◽  
Fisheries Bycatch ◽  
The Pacific Ocean ◽  
Nesting Beaches

Fisheries bycatch is a critical source of mortality for rapidly declining populations of leatherback turtles, Dermochelys coriacea . We integrated use-intensity distributions for 135 satellite-tracked adult turtles with longline fishing effort to estimate predicted bycatch risk over space and time in the Pacific Ocean. Areas of predicted bycatch risk did not overlap for eastern and western Pacific nesting populations, warranting their consideration as distinct management units with respect to fisheries bycatch. For western Pacific nesting populations, we identified several areas of high risk in the north and central Pacific, but greatest risk was adjacent to primary nesting beaches in tropical seas of Indo-Pacific islands, largely confined to several exclusive economic zones under the jurisdiction of national authorities. For eastern Pacific nesting populations, we identified moderate risk associated with migrations to nesting beaches, but the greatest risk was in the South Pacific Gyre, a broad pelagic zone outside national waters where management is currently lacking and may prove difficult to implement. Efforts should focus on these predicted hotspots to develop more targeted management approaches to alleviate leatherback bycatch.

scholarly journals A root for massive crown-of-thorns starfish outbreaks in the Pacific Ocean

2021 ◽  
Author(s):  
Nina Yasuda ◽  
June Inoue ◽  
Michael R. Hall ◽  
Manoj R. Nair ◽  
Mehdi Adjeroud ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Environmental Changes ◽  
French Polynesia ◽  
The Philippines ◽  
Marshall Islands ◽  
Western Pacific ◽  
Central Pacific ◽  
The Pacific ◽  
The Pacific Ocean ◽  
The Western Pacific

AbstractRecurring outbreaks of crown-of-thorns starfish (COTS) severely damage healthy corals in the Western Pacific Ocean. To determine the source of outbreaking COTS larvae and their dispersal routes across the Western Pacific, complete mitochondrial genomes were sequenced from 243 individuals collected in 11 reef regions. Our results indicate that Pacific COTS comprise two major clades, an East-Central Pacific clade (ECP-C) and a Pan-Pacific clade (PP-C). The ECP-C consists of COTS from French Polynesia (FP), Fiji, Vanuatu and the Great Barrier Reef (GBR), and does not appear prone to outbreaks. In contrast, the PP-C, which repeatedly spawns outbreaks, is a large clade comprising COTS from FP, Fiji, Vanuatu, GBR, Papua New Guinea, Vietnam, the Philippines, Japan, Micronesia, and the Marshall Islands. Given the nature of Pacific Ocean currents, the vast area encompassing FP, Fiji, Vanuatu, and the GBR likely supplies larvae for repeated outbreaks, exacerbated by anthropogenic environmental changes, such as eutrophication.

scholarly journals Persistence of deeply sourced iron in the Pacific Ocean

2015 ◽  
Vol 112 (5) ◽  
pp. 1292-1297 ◽  
Author(s):  
Tristan J. Horner ◽  
Helen M. Williams ◽  
James R. Hein ◽  
Mak A. Saito ◽  
Kevin W. Burton ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Carbon Fixation ◽  
Global Ocean ◽  
Oceanic Circulation ◽  
Multiple Sources ◽  
Central Pacific ◽  
Central Pacific Ocean ◽  
The Past ◽  
The Pacific ◽  
The Pacific Ocean

Biological carbon fixation is limited by the supply of Fe in vast regions of the global ocean. Dissolved Fe in seawater is primarily sourced from continental mineral dust, submarine hydrothermalism, and sediment dissolution along continental margins. However, the relative contributions of these three sources to the Fe budget of the open ocean remains contentious. By exploiting the Fe stable isotopic fingerprints of these sources, it is possible to trace distinct Fe pools through marine environments, and through time using sedimentary records. We present a reconstruction of deep-sea Fe isotopic compositions from a Pacific Fe−Mn crust spanning the past 76 My. We find that there have been large and systematic changes in the Fe isotopic composition of seawater over the Cenozoic that reflect the influence of several, distinct Fe sources to the central Pacific Ocean. Given that deeply sourced Fe from hydrothermalism and marginal sediment dissolution exhibit the largest Fe isotopic variations in modern oceanic settings, the record requires that these deep Fe sources have exerted a major control over the Fe inventory of the Pacific for the past 76 My. The persistence of deeply sourced Fe in the Pacific Ocean illustrates that multiple sources contribute to the total Fe budget of the ocean and highlights the importance of oceanic circulation in determining if deeply sourced Fe is ever ventilated at the surface.

scholarly journals Stakelama pacifica gen. nov., sp. nov., a new member of the family Sphingomonadaceae isolated from the Pacific Ocean

2010 ◽  
Vol 60 (12) ◽  
pp. 2857-2861 ◽  
Author(s):  
Chuang Chen ◽  
Qiang Zheng ◽  
Ya-Nan Wang ◽  
Xiao-Jun Yan ◽  
Li-Kai Hao ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Rrna Gene ◽  
Aerobic Bacterium ◽  
Central Pacific ◽  
Central Pacific Ocean ◽  
The Pacific ◽  
The Family ◽  
Novel Genus And Species ◽  
The Pacific Ocean ◽  
Ubiquinone 10

A Gram reaction-negative, weakly motile, non-spore-forming, rod-shaped, aerobic bacterium designated strain JLT832T was isolated from surface water of the central Pacific Ocean and formed yellow colonies on rich organic (RO) medium. The strain was oxidase-negative and catalase-positive. Acid was produced from mannitol, glucose, sucrose, lactose, sorbitol, maltose, (+)-trehalose and d-fructose. No acid was produced from d-(+)-xylose. The major cellular fatty acids of strain JLT832T were C18 : 1 ω7c, C14 : 0 2-OH and C16 : 0. The major polar lipids were sphingoglycolipid, diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. Ubiquinone-10 and spermidine were present as the major quinone and polyamine, respectively. The genomic DNA G+C content of strain JLT832T was 66.0±0.5 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the new isolate formed a tight branch within the family Sphingomonadaceae but was clearly separate from established genera in this family. The sequence similarities between the new isolate and type strains of established genera ranged from 90.5 to 94.9 %. Based on these data, strain JLT832T constitutes a novel genus and species, for which the name Stakelama pacifica gen. nov., sp. nov. is proposed. The type strain of Stakelama pacifica is JLT832T (=CGMCC 1.7294T =LMG 24686T).

“Creeping Jurisdiction” by the Small Islands of the Pacific Ocean in the Context of Management of the Tuna Fisheries

2015 ◽  
Vol 30 (3) ◽  
pp. 477-511 ◽  
Author(s):  
Michel Morin
Keyword(s):  
Pacific Ocean ◽  
Small Island ◽  
Small Islands ◽  
Central Pacific ◽  
Central Pacific Ocean ◽  
The Pacific ◽  
National Jurisdiction ◽  
The Pacific Ocean ◽  
Tuna Fisheries ◽  
Tuna Fishery

The tuna fishery of the Western and Central Pacific Ocean occurs for the greater part in waters under the sovereignty or jurisdiction of coastal States which qualify as small island developing States (sids); this fishery is managed by the Western and Central Pacific Fisheries Commission (wcpfc). On account of the majority they represent, the sids strive for the adoption of measures which would benefit them. This article discusses the effect of these measures which may give the impression that the delicate balance reached with the adoption of the losc between the rights of coastal States and other States is being upset; this can be regarded as a kind of ‘creeping jurisdiction’. Three issues are considered: the quasi-exemption of application of many rules by the sids, the issue of the application of the Convention in the various areas under national jurisdiction and the requirements for the exercise of navigational rights.

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