Eastern Pacific Rim Research Articles

Living on the Edge: Hawksbill turtle nesting and conservation along the Eastern Pacific Rim

Prior to 2007, efforts to monitor and conserve hawksbill turtles ( Eretmochelys imbricata ) in the eastern Pacific Ocean were opportunistic and records were virtually non-existent. The first abundance estimates were published in 2010, but contained limited data on the species. Ongoing research since that time has led to the identification of several rookeries, including sites containing large proportions of the overall hawksbill nesting currently known to occur in the region. Monitoring projects were established at several sites and have since provided substantial nesting data on the species. Here we summarize data collected between 1983 and March 2016 from all sites (n = 9) confirmed to host >10 nests in any given season to provide an update on hawksbill nesting in the eastern Pacific. We documented a total of 3,508 hawksbill nests, 265,024 hatchlings and 528 individual nesting females in the region. The vast majority of these records (99.4%, 99.9% and 99.6%, respectively) were generated subsequent to 2007, coinciding with the discovery of eight of the nine rookeries included in this study and the organization of monitoring efforts at those sites, which led to the increased documentation conferred here. Our findings should not be misconstrued as increases in actual nesting or signs of recovery, which could diminish the ongoing need for conservation actions, but rather as optimism, that there is still an opportunity to restore the species in the eastern Pacific. The top three sites in terms of average annual number of nests were Estero Padre Ramos (Nicaragua; 213.2 ± 47.6 nests), Bahia de Jiquilisco (El Salvador; 168.5 ± 46.7 nests) and Aserradores (Nicaragua; 100.0 ± 24.0 nests), and all three sites are located in mangrove estuaries in Central America, highlighting the importance of these rookeries/habitats for the survival and recovery of hawksbills in the region. The remaining six sites received between 6.9 ± 7.3 nests (Costa Careyes, Mexico) and 59.3 ± 17.7 nests (Los Cobanos, El Salvador) annually. By integrating data collected on nesting hawksbills with local conservation realities at the most important known hawksbill rookeries in the eastern Pacific, we provide a more holistic view of the conservation status and management needs of the species in this ocean region.

Terminal Pleistocene and Early Holocene fishing strategies at Quebrada Jaguay and the Ring Site, southern Perú

Much of the discussion regarding the peopling of the Americas during the Terminal Pleistocene and Early Holocene is focussed on advocating either a terrestrial route through an ice-free corridor or a coastal route along the Pacific rim. Central to this question is the potential of marine resources to sustain human endeavours. A growing body of archaeological data from the eastern Pacific rim shows that people did use marine resources as they moved south through the hemisphere and that they took advantage of the opportunities and challenges of coastal life in a wide range of different habitats. This is particularly evident in the vertebrate remains recovered from two shell deposits on the southern coast of Perú: Quebrada Jaguay and the Ring Site. Jaguay is one of the earliest known Terminal Pleistocene coastal sites in the hemisphere and the Ring Site was occupied during the Early Holocene. The sites are located within ca. 120km of one another. Together, they document both the antiquity and the persistence of maritime strategies in southern Perú. At Jaguay the focus was on two fishes from a relatively high trophic level. The catch at the Ring Site was richer, more diverse, and drawn from a broader range of trophic levels. These data join a growing body of evidence demonstrating that discussions about the peopling of the Americas that presume marine resources were inferior to terrestrial ones, that propose simple models assuming a uniform, homogeneous “coastal” strategy prevailed, or that evaluate data in terms of stark dichotomies such as hunting versus fishing, simple versus complex, inland versus coastal, and mobility versus sedentism, fail to capture the richness of human solutions to life on this, or any, coast.

Geochemical differences between subduction- and collision-related copper-bearing porphyries and implications for metallogenesis

Porphyry Cu (–Mo–Au) deposits occur not only in continental margin–arc settings (subduction-related porphyry Cu deposits, such as those along the eastern Pacific Rim (EPRIM)), but also in continent–continent collisional orogenic belts (collision-related porphyry Cu deposits, such as those in southern Tibet). These Cu-mineralized porphyries, which develop in contrasting tectonic settings, are characterized by some different trace element (e.g., Th, and Y) concentrations and their ratios (e.g., Sr/Y, and La/Yb), suggesting that their source magmas probably developed by different processes. Subduction-related porphyry Cu mineralization on the EPRIM is associated with intermediate to felsic calc-alkaline magmas derived from primitive basaltic magmas that pooled beneath the lower crust and underwent melting, assimilation, storage, and homogenization (MASH), whereas K-enriched collision-related porphyry Cu mineralization was associated with underplating of subduction-modified basaltic materials beneath the lower crust (with subsequent transformation into amphibolites and eclogite amphibolites), and resulted from partial melting of the newly formed thickened lower crust. These different processes led to the collision-related porphyry Cu deposits associated with adakitic magmas enriched by the addition of melts, and the subduction-related porphyry Cu deposits associated with magmas comprising all compositions between normal arc rocks and adakitic rocks, all of which were associated with fluid-dominated enrichment process.In subduction-related Cu porphyry magmas, the oxidation state (fO2), the concentrations of chalcophile metals, and other volatiles (e.g., S and Cl), and the abundance of water were directly controlled by the composition of the primary arc basaltic magma. In contrast, the high Cu concentrations and fO2 values of collision-related Cu porphyry magmas were indirectly derived from subduction modified magmas, and the large amount of water and other volatiles in these magmas were controlled in part by partial melting of amphibolite derived from arc basalts that were underplated beneath the lower crust, and in part by the contribution from the rising potassic and ultrapotassic magmas. Both subduction- and collision-related porphyries are enriched in potassium, and were associated with crustal thickening. Their high K2O contents were primarily as a result of the inheritance of enriched mantle components and/or mixing with contemporaneous ultrapotassic magmas.

Monitoring Stock‐Specific Abundance, Run Timing, and Straying of Chinook Salmon in the Columbia River Using Genetic Stock Identification (GSI)

AbstractGenetic stock identification (GSI) provides a method of characterizing stock‐specific abundance, run timing, and straying as they pertain to the population demographics and behavior of both hatchery and wild fish and thus assists with fisheries management. In this study, tissues were collected and genotyped at 13 microsatellite loci from adult Chinook Salmon Oncorhynchus tshawytscha that passed Bonneville Dam during four consecutive migration years (2004–2007). GSI methods were used to estimate the proportions of stocks in a broad genetic baseline, with high‐density coverage of Chinook Salmon across the eastern Pacific Rim. The estimates of abundance for interior Columbia River stocks showed widespread decline consistent with a shift to poor ocean conditions during the years when the fish in this study were at sea, but divergent stock‐ and age‐specific patterns were also observed. For example, the upper Columbia River spring‐run stock experienced a unique net gain in abundance during this period, and the interior Columbia River summer–fall‐run stock experienced a delayed decline of 4‐year‐olds. Stocks with early run timing shifted to later migrations. However, run timing distributions did not shift unidirectionally for all stocks across years, and stock membership in three major run timing categories was maintained. Of 9,215 total adults sampled, 27 (0.3%) were out‐of‐basin strays and a quarter of the strays were putatively of wild origin. The general concordance of GSI results with those based on more traditional methods supports the effectiveness of GSI as a tool for fisheries management.Received May 5, 2013; accepted October 23, 2013Published online February 10, 2014

Sedimentary Crust and Metallogeny of Granitoid Affinity: Implications from the Geotectonic Histories of the Circum‐Japan Sea Region, Central Andes and Southeastern Australia

AbstractMetallogeny of granitoid affinity was reviewed from the aspect of geotectonic history of the continental crust, particularly of the genesis of sedimentary crust involved in magmatism. The redox state of granitoids and related mineralization shows a remarkable contrast between the east and west sides of the Pacific Rim, but if examined closely, the reduced‐type and oxidized‐type granitoid provinces are juxtaposed in three regions: the circum‐Japan Sea region, the central Andes, and the Lachlan Fold Belt in southeastern Australia. Comparative study of these regions revealed that the reduced‐type magmatism associated with Sn mineralization generated in thick sedimentary crust which formed in three geotectonic environments: (i) accretionary terrane along a subduction zone (e.g. Jurassic East Asia), (ii) continental rift (e.g. Early Paleozoic Andes), and (iii) mega‐fan (e.g. Early Paleozoic southeastern Australia). A collisional orogen can provide large amounts of clastic sediment to these environments. The age gap between the magmatism and sedimentation varies depending on the tectonic evolution of individual regions. Thin sedimentary crust may not play an essential role for the reduced‐type magmatism. The oxidized‐type magmatism associated with porphyry Cu and other mineralization generated in the crust which was initially carbon‐free igneous crust or modified from sedimentary crust by magmatism. Subduction‐related basaltic magmas are relatively oxidized, and may enhance fO2 conditions of granitoid activity. Repeated magmatism in a monotonous convergent margin may be favorable for porphyry Cu mineralization as exemplified in the eastern Pacific Rim.

ICDD Regional Co-chair of Eastern Pacific Rim

ICDD Regional Co-chair of Eastern Pacific Rim

A New Early Miocene Species of Pogonias (Teleostei: Sciaenidae) Based on Otoliths from California

Abstract A new species of early Miocene croaker of the genus Pogonias (Perciformes: Sciaenidae) from the marine upper Olcese Sand, southeastern San Joaquin Valley, Kern County, California is described based on saccular ( = sagittae) otoliths. This is the first fossil record of the genus Pogonias from the eastern Pacific Rim. It is hypothesized that this new species of Pogonias or its ancestor emigrated from the Gulf Stream of the western Atlantic into the eastern Pacific via the Panama seaway during or prior to the late early Miocene.

Terminal Pleistocene and Early Holocene Occupations of Isla de Cedros, Baja California, Mexico

ABSTRACT Isla de Cedros is a high, rocky island located on the Pacific Coast of Baja California 685 km south of San Diego. Its arid but temperate marine climate provides excellent conditions of archaeological preservation and visibility. Over the last five years, the Proyecto Arqueologico Isla de Cedros has documented a diverse and rich archaeological record on the island. In addition to many more recent deposits, at least two coastal shell middens have been identified that were occupied during the Early Holocene and Terminal Pleistocene. Initial investigation of these sites, including 14C dating and limited excavations at the largest and most intact example (PAIC-44, Cerro Pedregoso), provides an opportunity to address issues related to the nature and antiquity of maritime adaptations along the eastern Pacific Rim, and potentially the peopling of the New World.

NerkaSim: A Research and Educational Tool to of Pacific Salmon in a Dynamic Environment

Abstract This paper introduces NerkaSim, a computer program used to simulate and visualize the life history of Pacific salmon in a dynamic ocean environment. The computer program enables users to (1) archive and visualize biophysical oceanographic data; (2) execute a spatially explicit, individually based Pacific salmon model that can include migration, growth, and mortality processes; and (3) produce images of simulated migration trajectories and bioenergetic variables in both space and time. We anticipate a demand for the model for basic and applied research applications, where it can serve as a platform to explore hypotheses concerning migration, growth, and mortality processes for salmon in coastal and high-seas environments. Although designed to address issues related to British Columbia's Fraser River sockeye salmon (Oncorhynchus nerka), the model can easily be customized to accommodate different salmon species across the eastern Pacific Rim. Distributed as freeware, we hope that NerkaSim will becom...

70 Million Years of Coastal Upwelling in California; Source Rocks and Paleoceanography: ABSTRACT

The Late Mesozoic-Cenozoic marine sequence of California displays a unique record of coastal upwelling and productivity in the form of distinctive diatomaceous and organic-rich deposits including the upper Cretaceous-lower Paleocene Moreno Formation, the Eocene Kreyenhagen Formation and the Miocene Monterey Formation. Unique sedimentological characteristics of these ancient upwelling systems include (a) Finely laminated biosiliceous-rich shales (>30% biogenic silica content), (b) Distinctive laminae composed by monospecific diatom resting spores, (c) Good source rock quality (>300 mg HC/mg org C), and (d) High accumulation rates in mid water anoxic conditions. Detailed study of individual laminae in sediments of these formations revealed concentration of monospecific diatom resting spores and an abundance of Stephanopyxis sp. and Coscinodiscus sp. Like Recent upwelling systems, preserved laminations of monospecific resting spores reflect strong seasonal upwelling that lead to high organic matter production and enhancement of anoxia. The presence of spores in the ancient and modern upwelling systems is evidence that diatoms have adapted and successfully competed in the highly productive California Margin since the Late Cretaceous. The Moreno, the Kreyenhagen and the Monterey Formation account for a significant portion of major petroleum source beds in California and contain an important record of coastal upwelling and paleoceanographic changemore » in the northeastern Pacific Ocean over the past 70 million years. It is suggested that potential Late Maestrichtian source rocks could have been deposited along other favorable upwelling areas of the Eastern Pacific Rim.« less

'…the cheapest thing in Australia is the girls'

Australian foreign policy reached a watershed in late 1941/early 1942. As the Japanese continued their rapid advance through Southeast Asia and into New Guinea, apprehensive Australians believed their country could be next. The government also knew their traditional ally Britain would not come to their aid should the Japanese invade Australia, and as most of their own forces were already out of the country, the remainder would have provided a totally inadequate defence. For Prime Minister Curtin and his advisers it was America that had to provide protection for Australia; both for its own sake, and as the base from which the Japanese advance through the Eastern Pacific rim from North to South could be halted.

Prevalence and distribution of serum neutralizing antibodies to Tillamook (bovine) calicivirus in selected populations of marine mammals.

Neutralizing antibodies to Tillamook calicivirus (TCV) were found in sera collected from California sea lions (Zalophus c. californianus Lesson) in 1983 and 1984 and in sera collected from Steller sea lions (Eumetopias jubatus Schreber) in 1976 and 1985. The combined prevalence of antibodies for these two species was 10/228 = 4.38%. Titers ranged from 1:20 (five animals), to 1:40 (four animals), to 1:80 (one animal) by standard microtiter neutralization assay. The seropositive pinnipeds were dispersed widely along the margins of the eastern Pacific rim, from the Bering Sea to the Santa Barbara Channel. Antibodies to TCV were not found in sera collected from northern fur seals (Callorhinus ursinus L.), Pacific walruses (Odobenus rosmarus divergens Illiger), seals of the family Phocidae, or several cetacean species. Tillamook calicivirus was isolated originally in 1981 from dairy calves in Oregon; the finding of neutralizing antibodies in two widely distributed species of sea lions suggests the possibility of a marine origin for this agent.

Taxonomic and nomenclatural notes on North Pacific marine algae

Abstract Various changes in nomenclature are made for twelve species of marine algae in the North Pacific. Some of these changes affect species previously known in Japan and the west coast of North America under different names. Other changes combine or place in synonymy species from the eastern Pacific rim. The status of three green algae, one brown and eight red algae is in volved in these changes.