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The present-day population structure of a species reflects the influence of population history as well as contemporary processes. Little is known about the mechanisms that have shaped the geographical distribution of genetic diversity in marine species present on the south-eastern Pacific (SEP) coast. Here we provide the first comprehensive phylogeographical study of a species distributed along the SEP coast by analysing the endemic and emblematic muricid gastropod Concholepas concholepas. The study localities were distributed along the SEP coast ranging from Matarani (11° S) to Puerto Eden (49° S), crossing three major biogeographical provinces: Peruvian Province, Intermediate Area and Magellanic Province. A total of 337 specimens of C. concholepas were collected from 14 localities in the three biogeographical provinces/areas. Mitochondrial cytochrome oxidase I (COI) gene partial sequences (658 bp) were obtained and analysed using coalescence-based methods to infer molecular diversity and phylogeographical patterns. Across the 337 individuals, we found a large diversity, with a total of 179 haplotypes at the COI gene fragment. Although a slight decrease in gene diversity was observed from north to south, an analysis of molecular variance did not reveal any significant spatial population differentiation from Peru to the tip of Chile, not even across the recognized biogeographical boundaries at 30° S and 42° S. In addition, a star-like haplotype network suggested the past occurrence of a rapid demographic and geographical expansion over the total range examined. Calculations of the onset of this expansion suggest that it might be due to climatic conditions during the period of the marine isotope stage 11 (MIS 11, 400,000 years ago), the longer and warmer interglacial episode during the Pleistocene epoch. Our phylogeographical analyses indicate that in the recent past C. concholepas mitochondrial DNA lineages underwent a sudden population expansion event. In addition, our data do not support the hypothesis of concordance between biogeographical barriers and phylogeographical breaks along the SEP coast. These two results are in accordance with the paradigm of high larval dispersal ability in marine species with an extended pelagic larval phase.

Nitrous oxide (N 2 O) is a potent greenhouse gas and ozone depleting substance, with the ocean accounting for about one third of global emissions. In marine environments, a significant amount of N 2 O is produced by biological processes in Oxygen Deficient Zones (ODZs). While recent technological advances are making surface N 2 O concentration more available, high temporal and spatial resolution water-column N 2 O concentration data are relatively scarce, limiting global N 2 O ocean models’ predictive capability. We present a N 2 O concentration, stable isotopic composition and isotopomer dataset of unprecedently large spatial coverage and depth resolution in the broader Pacific, crossing both the eastern tropical South and North Pacific Ocean ODZs collected as part of the GO-SHIP P18 repeat hydrography program in 2016/2017. We complement these data with dissolved gases (nitrogen, oxygen, argon) and nitrate isotope data to investigate the pathways controlling N 2 O production in relation to apparent oxygen utilization and fixed nitrogen loss. N 2 O yield significantly increased under low oxygen conditions near the ODZs. Keeling plot analysis revealed different N 2 O sources above the ODZs under different oxygen regimes. Our stable isotopic data and relationships between the N 2 O added by microbial processes (ΔN 2 O) and dissolved inorganic nitrogen (DIN) deficit confirm increased N 2 O production by denitrification under low oxygen conditions near the oxycline where the largest N 2 O accumulations were observed. The slope for δ 18 O-N 2 O versus site preference (SP, the difference between the central (α) and outer (β) N atoms in the linear N 2 O molecule) in the eastern tropical North Pacific ODZ was lower than expected for pure N 2 O reduction, likely because of the observed decrease in δ 15 N β . This trend is consistent with prior ODZ studies and attributed to concurrent production of N 2 O from nitrite with a low δ 15 N or denitrification with a SP >0‰. We estimated apparent isotope effects for N 2 O consumption in the ETNP ODZ of 3.6‰ for 15 N bulk , 9.4‰ for 15 N α , -2.3‰ for 15 N β , 12.0‰ for 18 O, and 11.7‰ for SP. These values were generally within ranges previously reported for previous laboratory and field experiments.

The hypothesis that biotic interactions strengthen toward lower latitudes provides a framework for linking community-scale processes with the macroecological scales that define our biosphere. Despite the importance of this hypothesis for understanding community assembly and ecosystem functioning, the extent to which interaction strength varies across latitude and the effects of this variation on natural communities remain unresolved. Predation in particular is central to ecological and evolutionary dynamics across the globe, yet very few studies explore both community-scale causes and outcomes of predation across latitude. Here we expand beyond prior studies to examine two important components of predation strength: intensity of predation (including multiple dimensions of the predator guild) and impact on prey community biomass and structure, providing one of the most comprehensive examinations of predator–prey interactions across latitude. Using standardized experiments, we tested the hypothesis that predation intensity and impact on prey communities were stronger at lower latitudes. We further assessed prey recruitment to evaluate the potential for this process to mediate predation effects. We used sessile marine invertebrate communities and their fish predators in nearshore environments as a model system, with experiments conducted at 12 sites in four regions spanning the tropics to the subarctic. Our results show clear support for an increase in both predation intensity and impact at lower relative to higher latitudes. The predator guild was more diverse at low latitudes, with higher predation rates, longer interaction durations, and larger predator body sizes, suggesting stronger predation intensity in the tropics. Predation also reduced prey biomass and altered prey composition at low latitudes, with no effects at high latitudes. Although recruitment rates were up to three orders of magnitude higher in the tropics than the subarctic, prey replacement through this process was insufficient to dampen completely the strong impacts of predators in the tropics. Our study provides a novel perspective on the biotic interaction hypothesis, suggesting that multiple components of the predator community likely contribute to predation intensity at low latitudes, with important consequences for the structure of prey communities.

Rare earth elements and yttrium (REY) are critical for advanced technological and environmental applications. REY‐enriched deep‐sea sediments have attracted attention as significant potential REY resources. However, efficient identification of these deposits in the open oceans is a persistent challenge. From integrated chemical leaching experiments and geochemical and rock magnetic analyses of two Eastern Pacific Ocean sediment cores, we find a coupled evolution between magnetic signatures and REY concentrations in sediment profiles. Apatite and Fe‐Mn (oxy)hydroxides are the primary REY carriers, while biogenic magnetite dominates the magnetic mineral assemblage. We elucidate here mechanistic linkages between mineral magnetic signals and REY enrichment, demonstrating their shared dependence on deep‐sea productivity cycles and redox dynamics. We propose that systematic magnetic property analyses could serve as a novel geophysical proxy for identifying REY‐rich sediment in marine environments.

The fundamental features of one kind of rarely known stratocumulus, which was termed as “Millipede Cloud,” occurred over the Eastern Pacific Ocean in 2017 were first documented by using Moderate Resolution Imaging Spectroradiometer (MODIS) satellite imagery. These clouds had long and meandering “central axes” extending from several hundreds to thousands kilometers, and a number of “radical cloud arms” extending several tens of kilometers in its two sides. Total 59 “Millipede Clouds,” 4 and 55 of them, were formed over the Northern and the Southern Hemispheres, respectively. Their environmental backgrounds were analyzed by using ERA5 reanalysis data and MODIS sensor Level‐2 data. The cloud top pressures of these “Millipede Clouds” were between 850 and 800 hPa, and their top heights were about 1–2 km. There existed “inversion layer” of air temperature near the cloud tops at 800 hPa, which strongly suggested that these clouds were lower stratocumulus in essence. Plain Language Summary “Millipede Cloud,” one kind of rarely known stratocumulus which looks like “Millipede” shape, is termed for the first time in this paper. It has an obvious “central axis” and a number of well‐organized “radial cloud arms” in two sides of the “central axis” extending in several tens of kilometers length. This paper introduces the fundamental features of “Millipede Clouds” occurred over the Eastern Pacific Ocean in 2017 from the perspective of satellite image. Totally, 59 “Millipede Clouds” were found to occur over the Eastern Pacific Ocean. Their geographic distribution, cloud top features and vertical structure of one typical case on 16 July 2017 were documented. Key Points The fundamental features of “Millipede Clouds” over the Eastern Pacific Ocean in 2017 were documented by using Moderate Resolution Imaging Spectroradiometer (MODIS) satellite imagery The environmental backgrounds of these “Millipede Clouds” were analyzed by using ERA5 reanalysis data and MODIS data The cloud top pressures of these “Millipede Clouds” are between 850 and 800 hPa, and their top heights are about 1–2 km

This research focuses on the description of the spatial and temporal distributions of mobulid ray species (Mobula birostris, Mobula mobular, Mobula thurstoni, Mobula tarapacana and Mobula munkiana) using data from the observer program (1993–2014) of the Inter-American Tropical Tuna Commission (IATTC). The tuna purse seine operations in the region extend from 70 to 150°W to 20°S-30°N. Significant differences on the captures per sets between fishing modes and species were found. Results showed that the most common species taken are M. thurstoni, M. mobular and M. birostris in School sets (sets on unassociated tuna schools). The temporal distributions showed high variability of the catches by species and years. The spatial distribution showed several areas of importance depending of the type of fishing, such as the coast of Peru, Galagapos or the Costa Rica Dome, and possible relationships with some oceanographic processes of the eastern Pacific Ocean (i.e. coastal and seasonal upwelling systems). The frequency of the captures per set showed that, although the greatest numbers caught in a set were very low (around 53.7% of sets with one capture), in some areas and periods there were captures of aggregates of hundreds of individuals of some of these species, such as Galapagos Islands during December, Costa Rica Dome during August, or Baja California during June. These events are of biological interest, and may offer good opportunities for conservation. This project has been developed with the aim of identifying the most important areas for these bycatch species and thus, improving the knowledge on them to reduce their mortality.

We present the first comprehensive review of the present and past shark and ray diversity in marine waters of Tropical America, examining the patterns of distribution in the Eastern Central Pacific (EP) and Western Central Atlantic (WA) realms. We identified the major regions of diversity and of endemism, and explored the relations to physical variables. We found a strong relationship between shark and ray diversity with area and coastal length of each province. The Tropical Northwestern Atlantic Province is characterized by high diversity and greater occurrence of endemic species, suggesting this province as the hotspot of sharks and rays in Tropical America. The historical background for the current biogeography is explored and analyzed. Referential data from 67 geological units in 17 countries, from both shallow and deep-water habitats, across five time-clusters from the Miocene to the Pleistocene were studied. New data include 20 new assemblages from six countries. The most diverse Neogene and extant groups of shark and ray are Carcharhiniformes and Myliobatiformes, respectively. The differentiation between Pacific and Atlantic faunas goes to at least the middle Miocene, probably related with the increasing closure of the Central American Seaway acting as a barrier. The highest faunal similarity between the assemblages from the EP and the WA at the early Miocene could be related to the lack of a barrier back then, but increased sampling is needed to substantiate this hypothesis.

White sharks ( Carcharodon carcharias ), have only one known natural predator in the ocean, the orca or killer whale ( Orcinus orca ). While interactions between these coexisting apex predators are known to occur, killer whales are adept at subduing adult white sharks and consuming their energy-rich livers. White sharks in turn are highly responsive to the appearance of killer whales and will vacate habitual feeding aggregations en masse to avoid predation. To date, interactions between killer whales and juvenile white sharks (~2.5 m TL) have been reported in South Africa, while the literature reports that these interactions occur primarily with larger white sharks, which naturally have a larger liver, and potentially compete with killer whales for pinniped prey. Here we document novel repeated predations by killer whales on juvenile white sharks in the Gulf of California. Aerial videos indicate consistency in killer whales’ repeated assaults and strikes on the sharks, indicating efficient ability by the mammals in attempting to induce tonic immobility in the prey and allow uninterrupted access to the liver for consumption. Once extirpated from the prey body, the target organ is shared between the members of the pods including calves. Images analysis of the killer whales involved in the attacks confirms previous observations of an existent pod possibly specialized in hunting elasmobranchs in this region.

Humpback whales undertake one of the longest known migrations of any mammal. While their migration route generally extends between latitudes, the breeding stocks are longitudinally separated and display high site fidelity to their feeding grounds. While there is an indication of certain breeding stocks overlapping with each other, the current information on the migration routes of humpback whales within the Southern Hemisphere limits our understanding of the extent of this exchange. Presented here is the longest documented great-circle distance between sightings on wintering grounds of two different ocean basins of an adult male humpback whale, involving two breeding stocks in the eastern Pacific (stock G) and southwest Indian Ocean (stock C). These two stocks are separated by a minimum of 120° longitude, and a great-circle distance of 13 046 km. This extreme distance movement demonstrates behavioural plasticity, which may play an important role in adaptation strategies to global environmental changes and perhaps be an evolved response to various pressures, underlining the importance of consolidation of global datasets on wide-ranging marine mammals.

This work assessed the sexual maturity of breeding females and males of black sea turtles (Chelonia mydas agassizii) from the population in Michoacan, Mexico. This study also provides the first report of the age at sexual maturity for male black sea turtles in the eastern Pacific. Using information on juvenile growth rate, length, and age at recruitment of juveniles in the developmental habitats in Baja California (Magdalena Bay), sexual maturity was estimated from the minimum and average standard carapace lengths (SCL) of nesting females (n = 1500) on Colola Beach and males (n = 132) captured at sea using the “swim up” technique. Differential sexual maturity was found in females and males. The minimum age at sexual maturity for males was 23.0 years at a minimum size of 61.1 cm SCL and the maximum age at sexual maturity was 32.5 years at a maximum size of 76.6 cm SCL. The minimum age of sexual maturity for nesting females was 24.9 years at a minimum size of 64.2 cm SCL, while the age of sexual maturity for maximum size was 42.9 years at a 93.4 cm SCL. Differences in the age at sexual maturity influence reproductive behavior and female carapace shape, impacting mating success.