52 research outputs found

    A Rifted Margin Origin for the Crescent Basalts and Related Rocks in the Northern Coast Range Volcanic Province, Washington and British-Columbia

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    The remarkable early to middle Eocene volcanic sequence of the Crescent Formation exposed on the Olympic Peninsula consists predominantly of tholeiitic to minor transitional alkaline basalts with sparse sedimentary interbeds. A composite section measured in the vicinity of the Dosewallips River includes 8.4 km of pillowed to massive submarine basalts overlain by 7.8 km of subaerial flows. An upper limit of about 48 Ma on the age of the Crescent basalts is indicated by faunal assemblages in sediments interbedded with the uppermost flows in the sequence and a circa 50 Ma 40Ar/39Ar age on a leucogabbro from the presumably correlative Bremerton Igneous Complex. Stratigraphically controlled samples collected from throughout the Crescent basalt sequence show that two distinctly different chemical types exist. The lower part of the sequence originated from a relatively depleted mantle course resembling normal (N) to enriched (E)-MORB. The upper flows have a chemistry resembling E-MORB to oceanic island tholeiites. This difference could be due to either variable metasomatism of a single source domain, or influx of a separate enriched-mantle source component during the extrusion of the upper part of the sequence. Paleomagnetic measurements indicate that the Crescent basalts have not been significantly rotated, nor translated northwards since their extrusion. Paleotectonic reconstructions show that formation of the Crescent basalts and the Coast Range volcanic province as a whole coincided with a marked increase in the velocity of oblique convergence of the Kula plate with North America at about 60 Ma. Other geologic, geochemical, and paleomagnetic data are consistent with the interpretation that extrusion occurred in a basin or series of basins formed by a rift system along the continental margin of North America. Rifting might have been initiated by the influence of a hotspot, an increase in the rate of oblique convergence, or the kinematic effects of the Kula-Farallon ridge as it migrated along the margin. If extrusion is related to the passage of the triple junction, then the Coast Ranges can be considered to be an important tectonic marker for early to middle Eocene plate reconstructions

    Recreational Fishing Impacts in an Offshore and Deep-Water Marine Park: Examining Patterns in Fished Species Using Hybrid Frequentist Model Selection and Bayesian Inference

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    No-take marine reserves are often located in remote locations far away from human activity, limiting perceived impact on extractive users but also reducing their use for investigating impacts of fishing. This study aimed to establish a benchmark in the distribution of fished species across the Ningaloo Marine Park – Commonwealth (NMP-Commonwealth), and adjacent comparable habitats within the Ningaloo Marine Park - State (NMP-State), in Western Australia to test if there was evidence of an effect of recreational fishing, as no commercial fishing is allowed within either marine park. We also examined whether the remote location of the newly established (2018) No-take Zone (NTZ), in NMP-Commonwealth, limits its use for studying the effects of fishing. Throughout the NMP-Commonwealth and NMP-State, where recreational fishing is permitted, we expected the abundance of recreationally fished fish species to increase with increasing distance to the nearest boat ramp, as a proxy of recreational fishing effort. Conversely, we did not expect the abundance of non-fished species and overall species richness to vary in response to the proxy for human activity. Distance to the nearest boat ramp was found to be a strong predictor of fished species abundance, indicating that the effect of recreational fishing can be detected across the NMP-Commonwealth. The effect of the NTZ on fished species abundance was weakly positive, but this difference across the NTZ is expected to increase over time. Habitat composition predictors were only found to influence species richness and non-fished species abundance. This study suggests a clear footprint of recreational fishing across the NMP-Commonwealth and as a result the new NTZ, despite its remote location, can act as a control in future studies of recreational fishing effects.publishedVersio

    Prospectus, December 2, 1975

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    PC NEWS IN BRIEF: 1975 FALL SEMESTER GRADS, PRESIDENT REPORTS, TRAFFIC STUDY AT PARKLAND; Campus FM Radio A Reality; StuGo proposes 18,000cut:Emergencymeetingslashes18,000 cut: Emergency meeting slashes ; editorials; Letters to the Editor; Roots & Radicals; Forum; Seniors visit P/C; Far Out Planet; Counseling Services Available at P/C; Questions, Just ask Bob; Karate Club; Phi Beta Lambda; Parkland, Sangamon combination; Library Report; Baby born to Reids; Distaff Side; Skylines: Secrets of Life; Parkland teacher stars in musical; Snow Queen contest, dance planned by StuGo; Wright accepts new Chevy; Christmas Music; Swingles Swing; Aw, c\u27mon, Denice; Public StuGo Meeting set for Dec. 6; Cardwell reports to Faculty Senate; Library Security System; Senator Resigns; Parkland Events; Dinner set for December 4; Staerkel scores lack of state funding; If Snow comes, can flu be far behind?; Library Hours; Prospectus Photo Contest; Attend StuGo Meeting: Students protest further cuts in StuGo budget; Ooops!; Two Plays set for Dec. 4 and &; Fly Navy; Snow Queen Candidates named; Good News; Vinyl Love; Foto-Funny\u27s; Country Bouquet: Chicano country ; Dear Bonnie; Art Works for P/C; Classified; U.S. returns vs. Illini; Cobras host Wabash in season opener; Sports Views: Parkland football may be in danger; 1975-76 Cobras Parkland Basketball Roster; 1975-1976 Parkland College Basketball Schedulehttps://spark.parkland.edu/prospectus_1975/1001/thumbnail.jp

    Do Behavioral Foraging Responses of Prey to Predators Function Similarly in Restored and Pristine Foodwebs?

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    Efforts to restore top predators in human-altered systems raise the question of whether rebounds in predator populations are sufficient to restore pristine foodweb dynamics. Ocean ecosystems provide an ideal system to test this question. Removal of fishing in marine reserves often reverses declines in predator densities and size. However, whether this leads to restoration of key functional characteristics of foodwebs, especially prey foraging behavior, is unclear. The question of whether restored and pristine foodwebs function similarly is nonetheless critically important for management and restoration efforts. We explored this question in light of one important determinant of ecosystem function and structure – herbivorous prey foraging behavior. We compared these responses for two functionally distinct herbivorous prey fishes (the damselfish Plectroglyphidodon dickii and the parrotfish Chlorurus sordidus) within pairs of coral reefs in pristine and restored ecosystems in two regions of these species' biogeographic ranges, allowing us to quantify the magnitude and temporal scale of this key ecosystem variable's recovery. We demonstrate that restoration of top predator abundances also restored prey foraging excursion behaviors to a condition closely resembling those of a pristine ecosystem. Increased understanding of behavioral aspects of ecosystem change will greatly improve our ability to predict the cascading consequences of conservation tools aimed at ecological restoration, such as marine reserves

    Recreational Fishing Impacts in an Offshore and Deep-Water Marine Park: Examining Patterns in Fished Species Using Hybrid Frequentist Model Selection and Bayesian Inference

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    No-take marine reserves are often located in remote locations far away from human activity, limiting perceived impact on extractive users but also reducing their use for investigating impacts of fishing. This study aimed to establish a benchmark in the distribution of fished species across the Ningaloo Marine Park – Commonwealth (NMP-Commonwealth), and adjacent comparable habitats within the Ningaloo Marine Park - State (NMP-State), in Western Australia to test if there was evidence of an effect of recreational fishing, as no commercial fishing is allowed within either marine park. We also examined whether the remote location of the newly established (2018) No-take Zone (NTZ), in NMP-Commonwealth, limits its use for studying the effects of fishing. Throughout the NMP-Commonwealth and NMP-State, where recreational fishing is permitted, we expected the abundance of recreationally fished fish species to increase with increasing distance to the nearest boat ramp, as a proxy of recreational fishing effort. Conversely, we did not expect the abundance of non-fished species and overall species richness to vary in response to the proxy for human activity. Distance to the nearest boat ramp was found to be a strong predictor of fished species abundance, indicating that the effect of recreational fishing can be detected across the NMP-Commonwealth. The effect of the NTZ on fished species abundance was weakly positive, but this difference across the NTZ is expected to increase over time. Habitat composition predictors were only found to influence species richness and non-fished species abundance. This study suggests a clear footprint of recreational fishing across the NMP-Commonwealth and as a result the new NTZ, despite its remote location, can act as a control in future studies of recreational fishing effects

    Marine protected areas

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    Marine Protected Areas (MPAs) are spatially delimited areas of the marine environment that are managed at least in part, for conservation of biodiversity. The number of MPAs declared worldwide is increasing exponentially Because MPAs can be declared for a variety of reasons, the specific goals of each MPA need to be specified to allow management agencies to assess the success of the MPA, and to guide monitoring and research activities within. Because of the complexity of processes within marine ecosystems, ecological changes associated with the declaration of MPAs vary greatly from one region to another and are difficult to predict accurately. Important factors that affect the way plants and animals respond to MPAs include distribution of habitat types, level of connectivity to nearby fished habitats, wave exposure, depth distribution, prior level of resource extraction, regulations, and level of compliance to regulations. The value of MPAs primarily relates to biodiversity conservation, fisheries, and as research and management tools, but they can also generate recreational, aesthetic and educational benefits. Conservation benefits are evident through increased habitat heterogeneity at the seascape level, increased abundance of threatened species and habitats, and maintenance of a full range of genotypes. Fisheries can benefit through spillover, increased dispersal of egg and larval propagules, and as insurance against stock collapse. Scientific benefits primarily relate to the use of MPAs as reference areas to assess the scale of human impacts on the environment, and as locations for the collection of data that are unobtainable in fished systems. Nevertheless, MPAs can also involve costs to human society through displaced fishing effort, short-term reductions in catches, false security, and through undesirable interactions within the biota. MPAs do not represent the universal panacea for all threats affecting marine ecosystems, but can be regarded as arguably the most important tool in the marine manager's toolbox

    Differential response to abiotic stress controls species distributions at biogeographic transition zones

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    Understanding range limits is critical to predicting species responses to climate change. Subtropical environments, where many species overlap at their range margins, are cooler, more light-limited and variable than tropical environments. It is thus likely that species respond variably to these multi-stressor regimes and that factors other than mean climatic conditions drive biodiversity patterns. Here, we tested these hypotheses for scleractinian corals at their high-latitude range limits in eastern Australia and investigated the role of mean climatic conditions and of parameters linked to abiotic stress in explaining the distribution and abundance of different groups of species. We found that environmental drivers varied among taxa and were predominantly linked to abiotic stress. The distribution and abundance of tropical species and gradients in species richness (alpha diversity) and turnover (beta diversity) were best explained by light limitation, whereas minimum temperatures and temperature fluctuations best explained gradients in subtropical species, species nestedness and functional diversity. Variation in community structure (considering species composition and abundance) was most closely linked to the combined thermal and light regime. Our study demonstrates the role of abiotic stress in controlling the distribution of species towards their high-latitude range limits and suggests that, at biogeographic transition zones, robust predictions of the impacts of climate change require approaches that account for various aspects of physiological stress and for species abundances and characteristics. These findings support the hypothesis that abiotic stress controls high-latitude range limits and caution that projections solely based on mean temperature could underestimate species' vulnerabilities to climate change

    Identification of scleractinian coral recruits from Indo-Pacific reefs

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    Study of the early life history of scleractinian corals has been hampered by the inability to identify recently settled juveniles. To increase taxonomic resolution of coral recruits, we compared the morphology of the skeleton of juveniles raised from known parents for 29 species in 21 genera and 12 families. Juveniles from only 3 families could be reliably distinguished throughout their 1st year of life: the Acroporidae, which have a porous coenosteum, prominent septa, and no columella; the Pocilloporidae, which have a solid coenosteum, prominent septa and a prominent columella; and the Poritidae, which have septa with prominent teeth. Juveniles in the remaining families examined could not be consistently distinguished. In these taxa, the skeleton began as an epitheca with little internal structure, growth was slow, and the pattern of septal development was similar. Within the 3 distinctive families, a number of other taxa could be recognized when juveniles were young. Genera of the Pocilloporidae could be distinguished by size differences in the diameter of the primary corallite. Isopora, Acropora, and Montipora juveniles could be distinguished by differences in the size of the corallum at settlement. Juveniles of the broadcast spawning Porites appear to be distinguished from those of brooding Porites by the pattern of septal development and by the small size at settlement. The number of taxa that could be distinguished was highest when juveniles were between 4 and 8 wk old. After this time, variation in the growth rates of individuals and thickening of the skeleton obscured differences between the taxa

    Decadal trends in marine reserves reveal differential rates of change in direct and indirect effects

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    Decadal-scale observations of marine reserves suggest that indirect effects on taxa that occur through cascading trophic interactions take longer to develop than direct effects on target species. Combining and analyzing a unique set of long-term time series of ecologic data in and out of fisheries closures from disparate regions, we found that the time to initial detection of direct effects on target species (±SE) was 5.13 ± 1.9 years, whereas initial detection of indirect effects on other taxa, which were often trait mediated, took significantly longer (13.1 ± 2.0 years). Most target species showed initial direct effects, but their trajectories over time were highly variable. Many target species continued to increase, some leveled off, and others decreased. Decreases were due to natural fluctuations, fishing impacts from outside reserves, or indirect effects from target species at higher trophic levels. The average duration of stable periods for direct effects was 6.2 ± 1.2 years, even in studies of more than 15 years. For indirect effects, stable periods averaged 9.1 ± 1.6 years, although this was not significantly different from direct effects. Populations of directly targeted species were more stable in reserves than in fished areas, suggesting increased ecologic resilience. This is an important benefit of marine reserves with respect to their function as a tool for conservation and restoration
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