Western North Atlantic Research Articles

Unraveling migratory corridors of loggerhead and green turtles from the Yucatán Peninsula and its overlap with bycatch zones of the Northwest Atlantic.

Bycatch represents a conservation problem when endangered species are affected. Sea turtles are highly vulnerable to this threat as their critical habitats overlap with fishing zones in all regions of the world. We used sequences of the mitochondrial DNA control region obtained from loggerhead (Caretta caretta) and green (Chelonia mydas) turtles to determine the migratory routes between nesting habitats in the Yucatán Peninsula and their critical marine habitats in the Northwest Atlantic. Mixed Stock Analysis revealed that loggerheads from Quintana Roo migrated to foraging areas in the northwestern Atlantic. Migratory routes used by green turtles are determined by their natal nesting colony: (1) green turtles from the Gulf of Mexico migrate to foraging aggregations in Texas and the northern Gulf of Mexico, (2) Mexican Caribbean turtles travel to foraging grounds in Florida, and (3) a smaller proportion of individuals born in the Yucatán Peninsula display a local connectivity pattern. Our results suggest that the migratory corridors used by Mexican loggerheads overlap with longline fisheries in the mid-Atlantic where sea turtle bycatch is comprised predominantly of immature individuals. Green turtles from the Yucatán Peninsula migrate to critical habitats that overlap with shrimp trawl fisheries within the Gulf of Mexico. Bycatch data and the identification of migratory corridors used by loggerheads and green turtles suggests that shrimp trawl fisheries on the east coast of the U.S. and the Gulf of Mexico pose a serious threat to the conservation and recovery of Mexican sea turtle populations.

The significant influence of the sea surface temperature anomalies over North Atlantic and the Maritime Continent on maize yield in Northeast China

Northeastern China (NEC) is the largest grain base in China. Improving understanding of the effect of climate change on grain production over NEC is conducive to providing immediate response strategies for grain production. In this study, the relationships of the maize production with the dry state during the different maize growth stage have been investigated using the year-to-year increment method. Results showed that the severe drought that occurred from the jointing to maturity period have exerted severe effects on the maize growth. Further analysis indicated that the sea surface temperature (SST) anomalies over North Atlantic and Maritime Continent in later spring are the important factors affecting the summer droughts over NEC. The late spring SST anomaly over North Atlantic can excite the Rossby waves from the western North Atlantic and propagate eastward to NEC. The snow anomaly over western Siberia in late spring and the soil moisture anomaly over NEC in summer are key factors linking the SST anomaly to drought over the NEC. On the other hand, the Maritime Continent SST anomaly in late spring can modulate the activity of the East Asian jet stream via the East Asia-Pacific (EAP) teleconnection, which can provide the favorable conditions for the soil moisture reduction over NEC. Eventually, a predictive model for maize yield over NEC is successfully developed by using the predictive indices of the North Atlantic and the Maritime Continental SST during late spring. Both the cross-validation and independent sample tests show that the calibrated prediction model is robust and exhibits high skill in predicting maize yield over NEC.

Possible Causes for the Unprecedented Low/High Tropical Cyclone Activities in the Northern Pacific/Atlantic in 2023 El Niño

AbstractThis study reported the unprecedented tropical cyclone (TC) activity in the western North Pacific (WNP) and North Atlantic (NA) during the developing year of the 2023/2024 El Niño. The possible causes behind these unusual features were addressed. In contrast to previous El Niño events, an unusual low/high TC genesis number in the WNP/NA was identified during the typhoon season (June–November) in 2023. Meanwhile, the mean TC genesis location in the WNP exhibited a La Niña‐like northwestward shift, rarely observed in an El Niño developing year. An observational diagnosis on TC‐genesis‐related large‐scale dynamics and thermodynamics revealed that the lower/higher TC numbers in the WNP/NA were primarily attributed to an anticyclonic/cyclonic anomaly linked to trans‐basin sea surface temperature anomalies in the tropics and extratropics. Additionally, weaker intraseasonal oscillation activity compared to previous El Niños also partially contributed to fewer TCs in the WNP.

Postrelease survival of undersized swordfish (Xiphias gladius) caught on pelagic longline gear in a U.S. commercial fishery in the western North Atlantic Ocean: Suppl. Fig. 3

Postrelease survival of undersized swordfish (Xiphias gladius) caught on pelagic longline gear in a U.S. commercial fishery in the western North Atlantic Ocean: Suppl. Fig. 3

Postrelease survival of undersized swordfish (Xiphias gladius) caught on pelagic longline gear in a U.S. commercial fishery in the western North Atlantic Ocean: Suppl. Fig. 2

Postrelease survival of undersized swordfish (Xiphias gladius) caught on pelagic longline gear in a U.S. commercial fishery in the western North Atlantic Ocean: Suppl. Fig. 2

Postrelease survival of undersized swordfish (Xiphias gladius) caught on pelagic longline gear in a U.S. commercial fishery in the western North Atlantic Ocean

Postrelease survival of undersized swordfish (Xiphias gladius) caught on pelagic longline gear in a U.S. commercial fishery in the western North Atlantic Ocean

Postrelease survival of undersized swordfish (Xiphias gladius) caught on pelagic longline gear in a U.S. commercial fishery in the western North Atlantic Ocean: Suppl. Fig. 1

Postrelease survival of undersized swordfish (Xiphias gladius) caught on pelagic longline gear in a U.S. commercial fishery in the western North Atlantic Ocean: Suppl. Fig. 1

Recurrent association between Trichodesmium colonies and calcifying amoebae

Abstract Colonies of the N2-fixing cyanobacterium Trichodesmium spp. constitute a consortium with multiple microorganisms that collectively exert ecosystem-level influence on marine carbon and nitrogen cycling, shunting newly fixed nitrogen to low nitrogen systems, and exporting both carbon and nitrogen to the deep sea. Here we identify a seasonally recurrent association between puff colonies and amoebae through a two-year survey involving over 10 000 Trichodesmium colonies in the Red Sea. This association was most commonly found in near-shore populations during spring. Microscopic observations revealed consistent amoebae morphology throughout the study, and both morphological characteristics and 18S rRNA gene sequencing suggested that these amoebae are likely to belong to the species Trichosphaerium micrum, an amoeba that forms a CaCO3 shell. Co-cultures of Trichosphaerium micrum and Trichodesmium grown in the laboratory suggest that the amoebae feed on heterotrophic bacteria and not Trichodesmium, which adds a consumer dynamic to the complex microbial interactions within these colonies. Sinking experiments with fresh colonies indicated that the presence of the CaCO3-shelled amoebae decreased colony buoyancy. As such, this novel association may accelerate Trichodesmium sinking rates and facilitate carbon and nitrogen export to the deep ocean. Amoebae have previously been identified in Trichodesmium colonies in the western North Atlantic (Bermuda and Barbados), suggesting that this type of association may be widespread. This association may add a new critical facet to the microbial interactions underpinning carbon and nitrogen fixation and fate in the present and future ocean.

DNA sequencing reveals higher taxonomic diversity of coralline algae (Corallinales and Hapalidiales, Rhodophyta) in the tropical western North Atlantic that complicates ecological studies

Abstract Understanding of non-geniculate coralline algal (NGCA) diversity, prevalence, and distribution in the tropical western North Atlantic is currently limited by reliance on morphological and anatomical features that are inadequate for species identifications. Reef surveys from two study sites, the Florida Keys (Florida, USA) and Roatán (Honduras), provided prevalence data for the main benthic organisms as well as relative abundance for NGCA genera. NGCA collected during these surveys and from additional sites and depths were identified using DNA sequences from two plastid genes, psbA and rbcL, and two nuclear genes, SSU and LSU, and supported by morphological and anatomical descriptions. Bayesian and Maximum Likelihood phylogenetic analyses, along with species delimitation and genetic distance methods, resolved 11 genera within two orders. Within the Corallinales, the genera Dawsoniolithon, Porolithon and Spongites each had one species, Harveylithon and Lithophyllum had two, Titanoderma three, Hydrolithon four, Neogoniolithon eight, and an unknown genus within the subfamily Neogoniolithoideae had 11 putative species. Within the Hapalidiales, the genera Phymatolithon and Roseolithon each had one species. This study reinforces the inability of morphological and anatomical features to distinguish NGCA species in the tropical western North Atlantic, resulting in substantial underestimations of species richness and diversity.

Supplemental description of Benedenia seriolae (Yamaguti, 1934) Meserve, 1938 (Monogenoidea: Capsalidae) and first record of the parasite infecting a wild greater amberjack, Seriola dumerili (Risso, 1810) Hureau and Tortonese, 1973 (Carangiformes: Carangidae) from the northern Gulf of Mexico

We herein provide a supplemental description of Benedenia seriolae (Yamaguti, 1934) Meserve, 1938 (Monogenoidea: Capsalidae Baird, 1853) based on specimens we collected from the skin of wild-caught greater amberjack (Seriola dumerili) in the northern Gulf of Mexico (GOM). Our specimens of B. seriolae from the GOM resemble those of Benedenia humboldti Baeza, Sepúlveda, and González, 2019 (from yellowtail amberjack, Seriola lalandi Valenciennes, 1833 [Carangidae] off Chile) by having a large body (>7000 μm in total length), non-overlapping anterior and posterior hamuli, an entirely sinistral and convoluted vas deferens, and a common genital pore as well as by lacking glands of Goto. It differs from B. humboldti by the shape of the penis tip. The 28S rRNA gene sequence differed from that of B. seriolae (from Japan) by 8 bp (1.1 %) and B. humboldti by 13 bp (2.8 %–1.7 %). The phylogenetic analysis recovered our sequences of B. seriolae sister to conspecific sequences from Japan, with that clade sister to B. humboldti from Chile. Benedenia was paraphyletic, suggesting some systematic revision to the genus could be warranted. Of 25 Benedenia spp., only Benedenia hendorffii (von Linstow, 1889) Odhner, 1905 had been reported previously from the GOM. Benedenia seriolae had previously not been reported from wild greater amberjack (previous records from greater amberjack were from sea cages only). This is also the first record of B. seriolae from the Northwestern Atlantic Ocean (GOM).

History of the Monographic Series Fishes of the Western North Atlantic

History of the Monographic Series Fishes of the Western North Atlantic

Reasons for Different Predictability of Tropical Cyclone Tracks in the Western North Pacific and Atlantic Oceans

Abstract Recent several studies have focused on the predictability of tropical cyclone track forecast. As a response to the question issued by Landsea and Cangialosi (2018) about "the approaching limit of predictability for tropical cyclone (TC) track prediction is near or has already been reached", Zhou and Toth (2020) (short for ZT20) and Yu et al. (2022) (short for Y22) have found that the limit of predictability for TC track prediction has not been reached both in Atlantic (ATL) and Western North Pacific (WNP) basins. However, the predictabilities are different in two basins, as ZT20 found that 1 day's improvement can be obtained through 10 years in ATL, while Y22 found that 2 days' improvement can be obtained through 15 years in WNP. To reveal the causes of this difference, the predictability of TC track in WNP is first investigated under the same framework as ZT20. Then important parameters that determined the predictabilities are found and analyzed. Results suggested that the growth rate of true track forecast error in WNP is higher than that in ATL, indicating a lower predictability in WNP. Further explorations suggested that TCs in WNP basin have averagely larger sizes, stronger intensities, lower-latitude locations, and poorer forecast skills of their guided flows. All these factors contribute to the larger track forecast error growth rate. Moreover, it is pointed out that as the improvement of forecast skills over years mainly due to the reduction of initial analysis errors, although a lower predictability is found in WNP, the forecast skill improvement in WNP is faster than that in ATL.

Legacy persistent organic pollutants among multiple cetacean species in the Northwest Atlantic

The historical contamination of eastern Canadian shelf waters remains an ongoing concern, predominantly stemming from anthropogenic discharges in the Great Lakes region. Although legacy persistent organic pollutants (POPs) were banned decades ago, it remains unclear whether their concentrations have sufficiently decreased to safer levels in cetaceans that feed in the continental shelf waters of the northwestern Atlantic. This study compares polychlorinated biphenyl (PCB) and organochlorine pesticide (OC) accumulation in six cetacean species sampled in the Northwest Atlantic from 2015 to 2022. We assessed the influence of relative trophic level and foraging habitat preferences on POP accumulations among species using stable isotopes and fatty acids as dietary tracers. We further identified the species most susceptible to the effects of these contaminants. Killer whales (Orcinus orca) exhibited the highest PCB (∼100 mg/kg lw) and OC concentrations, followed by other odontocetes, with lowest concentrations in mysticetes. Stable isotope analysis revealed an unexpected lack of correlation between δ15N values and contaminant levels. However, there was a positive correlation between δ13C values and POP concentrations. Cetaceans foraging on pelagic prey species, as indicated by elevated proportions of the FA markers 22:1n11 and 20:1n9, had lower contaminant loads compared to cetaceans with benthic/coastal FA signatures. PCB and DDT (dichlorodiphenyltrichloroethane) concentrations are lower now in most cetacean species than in the 1980s and 1990s, likely due to regulatory measures restricting their production and use. Although current PCB concentrations for most species are under the thresholds for high risks of immune and reproductive failure, concentrations in killer whales exceed all established toxicity thresholds, underscoring the need for further action to reduce sources of these contaminants to the continental shelf waters of the northwestern Atlantic.

Population structure of the Atlantic angel shark (Squatina dumeril) in United States waters of the western North Atlantic Ocean

Population structure of the Atlantic angel shark (Squatina dumeril) in United States waters of the western North Atlantic Ocean

Refined Estimates of Global Ocean Deep and Abyssal Decadal Warming Trends

AbstractDeep and abyssal layer decadal temperature trends from the mid‐1980s to the mid‐2010s are mapped globally using Deep Argo and historical ship‐based Conductivity‐Temperature‐Depth (CTD) instrument data. Abyssal warming trends are widespread, with the strongest warming observed around Antarctic Bottom Water (AABW) formation regions. The warming strength follows deep western boundary currents transporting abyssal waters north and decreases with distance from Antarctica. Abyssal cooling trends are found in the North Atlantic and eastern South Atlantic, regions primarily ventilated by North Atlantic Deep Water (NADW). Deep warming trends are prominent in the Southern Ocean south of about 50°S, the Greenland‐Iceland‐Norwegian (GIN) Seas and the western subpolar North Atlantic, with cooling in the eastern subpolar North Atlantic and the subtropical and tropical western North Atlantic. Globally integrated decadal heat content trends of 21.6 (±6.5) TW in the deep and 12.9 (±1.8) TW in the abyssal layer are more certain than previous estimates.

Bridging gas and aerosol properties between the northeastern US and Bermuda: analysis of eight transit flights

Abstract. The western North Atlantic Ocean is strongly influenced by continental outflow, making it an ideal region to study the atmospheric transition from a polluted coastline to the marine environment. Utilizing eight transit flights between the NASA Langley Research Center (LaRC) in Hampton, Virginia, and the remote island of Bermuda from NASA's Aerosol Cloud meTeorology Interactions oVer the western ATlantic Experiment (ACTIVATE), we examine the evolution of trace gas and aerosol properties off the US East Coast. The first pair of flights flew along the wind trajectory of continental outflow, while the other flights captured a mix of marine and continental air mass sources. For measurements within the boundary layer (BL), there was an offshore decline in particle N<100 nm, N>100 nm, CH4, CO, and CO2 concentrations, all leveling off around ∼900 km offshore from the LaRC. These trends are strongest for the first pair of flights. In the BL, offshore declines in organic mass fraction and increases in sulfate mass fraction coincide with increasing hygroscopicity based on f(RH) measurements. Free troposphere measurements show a decline in N<100 nm, but other measured parameters are more variable when compared to the prominent offshore gradients seen in the BL. Pollution layers exist in the free troposphere, such as smoke plumes, that can potentially entrain into the BL. This work provides detailed case studies with a broad set of high-resolution measurements to further our understanding of the transition between continental and marine environments.

On the relationship between paleomagnetic secular variation and excursions – Records from MIS 11 and 12 – ODP Leg 172, western North Atlantic Ocean

This study has developed paleomagnetic secular variation (PSV) records from Sites 1060, 1061, 1062, and 1063 (ODP Leg 172) from the western North Atlantic Ocean during MIS 11–12 (374–478 ka). We have identified 46 inclination features and 49 declination features that can be correlated among the records. We have also developed relative paleointensity records and identified 13 paleointensity features that can be correlated among them. These features can also be dated using the oxygen-isotope dated Global relative-paleointensity record PISO-1500 of Channell et al. (2009). There is one excursion located in these four records. We use the name Levantine/Bermuda Excursion developed elsewhere by Ryan (1972) and Channell et al. (2017). The Excursion occurred at 408 ± 4 ka. The excursion is recorded at Sites 1061, 1062, and 1063. The most detailed excursion records occur at Site 1062 where we have both shipboard PSV records and one u-channel PSV record of the excursion. The excursion has two intervals of excursional directions, one short interval (∼I ky) followed by a long interval (∼5 ky). Both intervals have counter-clockwise looping of the excursional directions and the excursion is considered to be a Class I Excursion (Lund et al., 2005). Statistical study of the PSV records after removal of the excursion directions has identified two characteristics of the ‘normal’ PSV. The first feature is a long-term (>104 yrs) deviation in inclination and declination averages from the overall site averages. These deviations suggest some type on long-term memory in the regional dynamo process. The second feature is the variation in PSV angular dispersion (a measure of directional variability). The angular dispersion is quite low (∼12°) for most of the 374–478 ka interval. But, there is a short (∼8 ky) interval with angular dispersion more than double the amplitude (∼25°-30°). This interval has a sharp (<3 ky) onset and termination, This interval contains the Levantine/Bermuda Excursion. Such high-angular dispersion intervals with associated excursions and low paleointensity appear to be regular distinctive features of the Brunhes Chron PSV.

Overwintering humpback whales adapt foraging strategies to shallow water environments at the mouth of the Chesapeake Bay, Virginia, USA

AbstractSome humpback whales from the Northwestern Atlantic population forgo migration to the Caribbean, spending winter months feeding along the U.S. mid‐Atlantic coast. We studied the foraging behavior of these whales at the mouth of the Chesapeake Bay, Virginia during winter from 2017 to 2022. While shipping channels here reach depths of up to 30 m, most of the area is 11–15 m deep. This shallow‐water environment poses physical constraints on classical humpback whale feeding modes. We deployed 20 digital acoustic tags (DTAGs) on humpback whales and identified foraging lunges from accelerometer data, detecting 788 lunges from 10 animals. Tagged whales averaged a single lunge per dive, lunging primarily in a horizontal orientation, with limited maneuvering compared to other study sites. Our results indicate that some elements of humpback whale foraging behavior are conserved across environments, but that the shallow depths in our study area constrain how animals are able to feed. The relatively high lunge rates we observed suggest this area is an important foraging ground. However, foraging in shipping channels increases the risk of ship strikes, which frequently occur in this area.

You Shall Not Pass: The Pacific Oxygen Minimum Zone Creates a Boundary to Shortfin Mako Shark Distribution in the Eastern North Pacific Ocean

ABSTRACTAimShoaling of large oxygen minimum zones (OMZs) that form along eastern margins of the world's oceans can reduce habitat availability for some pelagic fishes. Our aim was to test the hypothesis that habitat compression caused by shoaling of the Pacific OMZ in tropical regions creates a boundary to the southern distribution of shortfin mako sharks (Isurus oxyrinchus) in the Eastern North Pacific Ocean.LocationEastern North Pacific and Western North Atlantic oceans.MethodsWe compared environmental conditions between areas used by satellite‐tagged mako sharks in the Eastern North Pacific, encompassing the world's largest OMZ, to those used in the Western North Atlantic where no OMZ is present. In the Pacific we quantified the effects of temperature and dissolved oxygen (DO) on depth use and tested if sharks spent less time in areas with strong habitat compression over the OMZ than expected by chance.ResultsThe southern distribution of sharks in the Pacific corresponded with the apex of OMZ shoaling in the North Equatorial Current. Sharks in the Atlantic occupied areas with warm surface temperatures (≥ 26°C) more often than the Pacific, and waters with these temperatures in the Atlantic had greater DO at depth. Sharks in the Pacific reduced time near the surface in warm temperatures and consistently avoided depths with low DO and spent less time in areas with strong habitat compression than expected by chance.Main ConclusionsThe combination of warm surface temperatures and shoaling of the OMZ creates a soft boundary to mako shark movements in the Eastern North Pacific Ocean. The expected expansion of OMZs due to climate change could have considerable impact on future distribution of mako sharks and other pelagic fish. As such, development of species distribution models to predict the effects of climate change on pelagic fish distributions should incorporate oxygen availability.

Stakeholder Engagement as a Core Component of Recreational Marine Fisheries Research, Education, and Conservation

Effective modern conservation depends on active stakeholder participation. Although stakeholder engagement is increasing, the extent of this engagement and the successful application of outcomes to science and management varies regionally and among types of fisheries. A collaborative model that emphasizes knowledge coproduction with stakeholders better identifies research needs and conservation threats, and influences research and policy outcomes. Stakeholder integration can be facilitated by nongovernment organizations, such as boundary organizations. Bonefish and Tarpon Trust is a science‐based, conservation organization founded in 1998 by recreational fishers and fishing guides that focuses on marine recreational fisheries in the Caribbean Sea and western North Atlantic Ocean. The Trust engages fishers directly, incorporating their knowledge and perspectives to identify conservation concerns, shape research, contribute to data collection, and disseminate information, and work with resource managers and scientific researchers to address conservation and management needs. This approach is demonstrated in case studies that show integration of recreational fishers in science, assessment of conservation threats, and application of findings to management for the recreational flats fishery in the Caribbean Sea and western North Atlantic Ocean, in the context of broader efforts of stakeholder collaboration toward actionable science to inform management.