970 resultados para Atmospheric Conditions.
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This report presents the results of the 2007 baseflow condition surveys of the four major streams flowing through Santa Lucia Preserve- Las Garzas, Portrero, San Jose, and San Clemente Creeks. This report has been prepared for the Santa Lucia Conservancy and is primarily intended for the staff of Monterey County and California Department of Fish and Game, in accordance with the baseflow monitoring and reporting requirements outlined in County Conditions 14 and 15. The scope of this report is limited to the presentation and evaluation of existing baseflow conditions as required by Conditions 14 and 15, and is not intended as a comprehensive analysis. However, data presented here are an important part of the long term data set that will be used for future in depth watershed analyses. (Document contains 13 pages & 14 figs)
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Table of Contents [pdf, 0.01 Mb] Preface [pdf, 0.01 Mb] Masaaki Aota Long-term tendencies of sea ice concentration and air temperature in the Okhotsk Sea coast of Hokkaido [pdf, 0.05 Mb] Hajime Ito & Miki Yoshioka Geography of the seasonally ice covered seas [pdf, 0.5 Mb] George V. Shevchenko & Victor F. Putov On wind and tide induced sea-ice drift on the northeastern shelf of Sakhalin Island (analysis of radar data) [pdf, 0.96 Mb] Boris S. Dyakov, A.A. Nikitin, L. S. Muktepavel & T.A. Shatilina Variability of the Japan and Okhotsk Seas ice cover depending on geopotential field H500 over the Far-Eastern region [pdf, 0.10 Mb] Aleksandr G. Petrov & Nikolay A. Rykov Intermediate cold layer and ice cover in the Sea of Okhotsk [pdf, 0.37 Mb] Vladimir Ponomarev, Olga Trusenkova, Elena Ustinova & Dmitry Kaplunenko Interannual variations of oceanographic and meteorological characteristics in the Sea of Okhotsk [pdf, 0.16 Mb] George V. Shevchenko & Akie Kato Seasonal and interannual changes of atmospheric pressure, air and water temperature in the area of the Kuril Ridge [pdf, 0.13 Mb] George V. Shevchenko & Vladimir Yu. Saveliev Spatial variability of the wind field in the area of the Kuril Islands [pdf, 0.15 Mb] Alexander L. Figurkin & Igor A. Zhigalov Seasonal variability and specifity of the oceanological conditions in the northern Okhotsk Sea in 1997 [pdf, 1.04 Mb] Igor A. Zhabin Ventilation of the upper portion of the intermediate water in the Okhotsk Sea [pdf, 0.80 Mb] Vladimir A. Luchin & Alexander L. Figurkin Oceanographic conditions over the Kashevarov Bank [pdf, 0.61 Mb] Toshiyuki Awaji, Tomohiro Nakamura, Takaki Hatayama, Kazunori Akimoto & Takatoshi Takizawa Tidal exchange through the Kuril Straits [pdf, 2.01 Mb] Tomohiro Nakamura, Toshiyuki Awaji, Takaki Hatayama, Kazunori Akimoto, Takatoshi Takizawa & Masao Fukasawa Vertical mixing induced by tidally generated internal waves in the Kuril Straits [pdf, 0.83 Mb] Katsuro Katsumata & Ichiro Yasuda Water exchange between the Okhotsk Sea and the North Pacific Ocean estimated by simple models [pdf, 0.97 Mb] Konstantin A. Rogachev Oyashio west path culmination as the consequence of a rapid thermohaline transition in the Pacific Subarctic [pdf, 0.22 Mb] Yasuhiro Kawasaki On the year-to-year change in subarctic water characteristics around the Kuril Islands [pdf, 0.39 Mb] Alexander L. Figurkin & Evgeniy E. Ovsyannikov Influence of oceanological conditions of the West Kamchatka shelf waters on spawning grounds and on pollock egg distribution [pdf, 0.97 Mb] Igor E. Kochergin & Alexander A. Bogdanovsky Transport and turbulence characteristics for the northeastern Sakhalin shelf conditions [pdf, 0.08 Mb] Igor E. Kochergin, Alexander A. Bogdanovsky, Valentina D. Budaeva, Vyacheslav G. Makarov, Vasily F. Mishukov, S.N. Ovsienko, Victor F. Putov, L.A. Reitsema, J.W. Sciallabba, O.O. Sergucheva & P.V. Yarosh Modeling of oil spills for the shelf conditions of northeastern Sakhalin [pdf, 0.32 Mb] Valentina D. Budaeva & Vyacheslav G. Makarov A peculiar water regime of currents in the area of eastern Sakhalin shelf [pdf, 0.66 Mb] Nikolay A. Rykov The oceanographic databases on the Sakhalin shelf [pdf, 0.27 Mb] Akifumi Nakata, Iori Tanaka, Hiroki Yagi, Tomomi Watanabe, Gennady A. Kantakov & Andrew D. Samatov Formation of high-density water (over 26.8 sigma-t) near the La Perouse Strait (the Soya Strait) [pdf, 0.09 Mb] Minoru Odamaki & Kouji Iwamoto Currents and tidal observations by Hydrographic Department of Maritime Safety Agency, off the Okhotsk coast of Hokkaido [pdf, 0.16 Mb] Yasushi Fukamachi, Genta Mizuta, Kay I. Ohshima, Motoyo Itoh, Masaaki Wakatsuchi & Masaaki Aota Mooring measurements off Shiretoko Peninsula, Hokkaido in 1997-1998 [pdf, 0.19 Mb] Mikhail A. Danchenkov, David Aubrey & Stephen C. Riser Oceanographic features of the La Perouse Strait [pdf, 0.91 Mb] Iori Tanaka & Akifumi Nakata Results of direct current measurements in the La Perouse Strait (the Soya Strait), 1995-1998 [pdf, 0.06 Mb] Gennady A. Kantakov & George V. Shevchenko In situ observations of Tsushima and West-Sakhalin currents near La Perouse (Soya) Strait [pdf, 0.79 Mb] Irina Y. Bragina Geographical and biological characteristics of the net zooplankton in the southwestern part of the Sea of Okhotsk during 1987-1996 [pdf, 0.27 Mb] List of corresponding authors [pdf, 0.01 Mb] (Document pdf contains 193 pages)
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Preface [pdf, 0.01 Mb] James J. O'Brien The big picture - The ENSO of 1997-98 [pdf, 0.01 Mb] James E. Overland, Nicholas A. Bond & Jennifer Miletta Adams Atmospheric anomalies in 1997: Links to ENSO? [pdf, 0.54 Mb] Vladimir I. Ponomarev, Olga Trusenkova, Serge Trousenkov, Dmitry Kaplunenko, Elena Ustinova & Antonina Polyakova The ENSO signal in the northwest Pacific [pdf, 0.47 Mb] Robert L. Smith, A. Huyer, P.M. Kosro & J.A. Barth Observations of El Niño off Oregon: July 1997 to present (October 1998) [pdf, 1.31 Mb] Patrica A. Wheeler & Jon Hill Biological effects of the 1997-1998 El Niño event off Oregon: Nutrient and chlorophyll distributions [pdf, 1.13 Mb] William T. Peterson Hydrography and zooplankton off the central Oregon coast during the 1997-1998 El Niño event [pdf, 0.26 Mb] William Crawford, Josef Cherniawsky, Michael Foreman & Peter Chandler El Niño sea level signal along the west coast of Canada [pdf, 1.25 Mb] Howard J. Freeland & Rick Thomson The El Niño signal along the west coast of Canada - temperature, salinity and velocity [pdf, 0.49 Mb] Frank A. Whitney, David L. Mackas, David W. Welch & Marie Robert Impact of the 1990s El Niños on nutrient supply and productivity of Gulf of Alaska waters [pdf, 0.06 Mb] Craig McNeil, David Farmer & Mark Trevorrow Dissolved gas measurements at Stn. P4 during the 97-98 El Niño [pdf, 0.13 Mb] Kristen L.D. Milligan, Colin D. Levings & Robert E. DeWreede Data compilation and preliminary time series analysis of abundance of a dominant intertidal kelp species in relation to the 1997/1998 El Niño event [pdf, 0.05 Mb] S.M. McKinnell, C.C. Wood, M. Lapointe, J.C. Woodey, K.E. Kostow, J. Nelson & K.D. Hyatt Reviewing the evidence that adult sockeye salmon strayed from the Fraser River and spawned in other rivers in 1997 [pdf,0.03 Mb] G.A. McFarlane & R.J. Beamish Sardines return to British Columbia waters [pdf, 0.34 Mb] Ken H. Morgan Impact of the 1997/98 El Niño on seabirds of the northeast Pacific [pdf, 0.06 Mb] Thomas C. Royer & Thomas Weingartner Coastal hydrographic responses in the northern Gulf of Alaska to the 1997-98 ENSO event [pdf, 0.76 Mb] John F. Piatt, Gary Drew, Thomas Van Pelt, Alisa Abookire, April Nielsen, Mike Shultz & Alexander Kitaysky Biological effects of the 1997/98 ENSO in Cook Inlet, Alaska [pdf, 0.22 Mb] H.J. Niebauer The 1997-98 El Niño in the Bering Sea as compared with previous ENSO events and the "regime shift" of the late 1970s [pdf, 0.10 Mb] A.S. Krovnin, G.P. Nanyushin, M.Yu. Kruzhalov, G.V. Khen, M.A. Bogdanov, E.I. Ustinova, V.V. Maslennikov, A.M. Orlov, B.N. Kotenev, V.V. Bulanov & G.P. Muriy The state of the Far East seas during the 1997/98 El Niño event [pdf, 0.15 Mb] Stacy Smith & Susan Henrichs Phytoplankton collected by a time-series sediment trap deployed in the southeast Bering Sea during 1997 [pdf, 0.21 Mb] Cynthia T. Tynan Redistributions of cetaceans in the southeast Bering Sea relative to anomalous oceanographic conditions during the 1997 El Niño [pdf, 0.02 Mb] Akihiko Yatsu, Junta Mori, Hiroyuki Tanaka, Tomowo Watanabe, Kazuya Nagasawa, Yikimasa Ishida, Toshimi Meguro, Yoshihiko Kamei & Yasunori Sakurai Stock abundance and size compositions of the neon flying squid in the central North Pacific Ocean during 1979-1998 [pdf, 0.11 Mb] O.B. Feschenko A new point of view concerning the El Niño mechanism [pdf, 0.01 Mb] Nathan Mantua 97/98 Ocean climate variability in the northeast Pacific: How much blame does El Niño deserve? [pdf, 0.01 Mb] Vadim P. Pavlychev Sharp changes of hydrometeorological conditions in the northwestern Pacific during the 1997/1998 El Niño event [pdf, 0.01 Mb] Jingyi Wang Predictability and forecast verification of El Niño events [pdf, 0.01 Mb] (Document contains 110 pages)
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I REPORT OF THE PICES WORKSHOP ON THE OKHOTSK SEA AND ADJACENT AREAS (pdf, 0.1 Mb) 1. Outline of the workshop 2. Summary reports from sessions 3. Recommendations of the workshop 4. Acknowledgments II SCIENTIFIC PAPERS SUBMITTED FROM SESSIONS 1. Physical Oceanography Sessions (pdf, 4 Mb) A. Circulation and water mass structure of the Okhotsk Sea and Northwestern Pacific Valentina D. Budaeva & Vyacheslav G. Makarov Seasonal variability of the pycnocline in La Perouse Strait and Aniva Gulf Valentina D. Budaeva & Vyacheslav G. Makarov Modeling of the typical water circulations in the La Perouse Strait and Aniva Gulf region Nina A. Dashko, Sergey M. Varlamov, Young-Ho Han & Young-Seup Kim Anticyclogenesis over the Okhotsk Sea and its influence on weather Boris S. Dyakov, Alexander A. Nikitin & Vadim P. Pavlychev Research of water structure and dynamics in the Okhotsk Sea and adjacent Pacific Howard J. Freeland, Alexander S. Bychkov, C.S. Wong, Frank A. Whitney & Gennady I. Yurasov The Ohkotsk Sea component of Pacific Intermediate Water Emil E. Herbeck, Anatoly I. Alexanin, Igor A. Gontcharenko, Igor I. Gorin, Yury V. Naumkin & Yury G. Proshjants Some experience of the satellite environmental support of marine expeditions at the Far East Seas Alexander A. Karnaukhov The tidal influence on the Sakhalin shelf hydrology Yasuhiro Kawasaki On the formation process of the subsurface mixed water around the Central Kuril Islands Lloyd D. Keigwin Northwest Pacific paleohydrography Talgat R. Kilmatov Physical mechanisms for the North Pacific Intermediate Water formation Vladimir A. Luchin Water masses in the Okhotsk Sea Andrey V. Martynov, Elena N. Golubeva & Victor I. Kuzin Numerical experiments with finite element model of the Okhotsk Sea circulation Nikolay A. Maximenko, Anatoly I. Kharlamov & Raissa I. Gouskina Structure of Intermediate Water layer in the Northwest Pacific Nikolay A. Maximenko & Andrey Yu. Shcherbina Fine-structure of the North Pacific Intermediate Water layer Renat D. Medjitov & Boris I. Reznikov An experimental study of water transport through the Straits of Okhotsk Sea by electromagnetic method Valentina V. Moroz Oceanological zoning of the Kuril Islands area in the spring-summer period Yutaka Nagata Note on the salinity balance in the Okhotsk Sea Alexander D. Nelezin Variability of the Kuroshio Front in 1965-1991 Vladimir I. Ponomarev, Evgeny P. Varlaty & Mikhail Yu. Cheranyev An experimental study of currents in the near-Kuril region of the Pacific Ocean and in the Okhotsk Sea Stephen C. Riser, Gennady I. Yurasov & Mark J. Warner Hydrographic and tracer measurements of the water mass structure and transport in the Okhotsk Sea in early spring Konstantin A. Rogachev & Andrey V. Verkhunov Circulation and water mass structure in the southern Okhotsk Sea, as observed in summer, 1994 Lynne D. Talley North Pacific Intermediate Water formation and the role of the Okhotsk Sea Anatoly S. Vasiliev & Fedor F. Khrapchenkov Seasonal variability of integral water circulation in the Okhotsk Sea B. Sea ice and its relation to circulation and climate V.P. Gavrilo, G.A. Lebedev & A.P. Polyakov Acoustic methods in sea ice dynamics studies Nina M. Pestereva & Larisa A. Starodubtseva The role of the Far-East atmospheric circulation in the formation of the ice cover in the Okhotsk Sea Yoshihiko Sekine Anomalous Oyashio intrusion and its teleconnection with Subarctic North Pacific circulation, sea ice of the Okhotsk Sea and air temperature of the northern Asian continent C. Waves and tides Vladimir A. Luchin Characteristics of the tidal motions in the Kuril Straits George V. Shevtchenko On seasonal variability of tidal constants in the northwestern part of the Okhotsk Sea D. Physical oceanography of the Japan Sea/East Sea Mikhail A. Danchenkov, Kuh Kim, Igor A. Goncharenko & Young-Gyu Kim A “chimney” of cold salt waters near Vladivostok Christopher N.K. Mooers & Hee Sook Kang Preliminary results from a numerical circulation model of the Japan Sea Lev P. Yakunin Influence of ice production on the deep water formation in the Japan Sea 2. Fisheries and Biology Sessions (pdf, 2.8 Mb) A. Communities of the Okhotsk Sea and adjacent waters: composition, structure and dynamics Lubov A. Balkonskaya Exogenous succession of the southwestern Sakhalin algal communities Tatyana A. Belan, Yelena V. Oleynik, Alexander V. Tkalin & Tat’yana S. Lishavskaya Characteristics of pelagic and benthic communities on the North Sakhalin Island shelf Lev N. Bocharov & Vladimir K. Ozyorin Fishery and oceanographic database of Okhotsk Sea Victor V. Lapko Interannual dynamics of the epipelagic ichthyocen structure in the Okhotsk Sea Valentina I. Lapshina Quantitative seasonal and year-to-year changes of phytoplankton in the Okhotsk Sea and off Kuril area of the Pacific Lyudmila N. Luchsheva Biological productivity in anomalous mercury conditions (northern part of Okhotsk Sea) Inna A. Nemirovskaya Origin of hydrocarbons in the ecosystems of coastal region of the Okhotsk Sea Tatyana A. Shatilina Elements of the Pacific South Kuril area ecosystem Vyacheslav P. Shuntov & Yelena P. Dulepova Biota of the Okhotsk Sea: Structure of communities, the interannual dynamics and current status B. Abundance, distribution, dynamics of the common fishes of the Okhotsk Sea Yuri P. Diakov Influence of some abiotic factors on spatial population dynamics of the West Kamchatka flounders (Pleuronectidae) Gordon A. McFarlane, Richard J. Beamish & Larisa M. Zverkova An examination of age estimates of walleye pollock (Theragra chalcogramma) from the Sea of Okhotsk using the burnt otolith method and implications for stock assessment and management Larisa P. Nikolenko Migration of Greenland turbot (Reinhardtius hippoglossoides) in the Okhotsk Sea Galina M. Pushnikova Fisheries impact on the Sakhalin-Hokkaido herring population Vidar G. Wespestad Is pollock overfished? C. Salmon of the Okhotsk Sea: biology, abundance and stock identification Vladimir A. Belyaev, Alexander Yu. Zhigalin Epipelagic Far Eastern sardine of the Okhotsk Sea Yuri E. Bregman, Victor V. Pushnikov, Lyudmila G. Sedova & Vladimir Ph. Ivanov A preliminary report on stock status and productive capacity of horsehair crab Erimacrus isenbeckii (Brandt) in the South Kuril Strait Natalia T. Dolganova Mezoplankton distribution in the West Japan Sea Vladimir V. Efremov, Richard L. Wilmot, Christine M. Kondzela, Natalia V. Varnavskaya, Sharon L. Hawkins & Maria E. Malinina Application of pink and chum salmon genetic baseline to fishery management Vyacheslav N. Ivankov & Valentina V. Andreyeva Strategy for culture, breeding and numerous dynamics of Sakhalin salmon populations Alla M. Kovalevskaya, Natalia I. Savelyeva & Dmitry M. Polyakov Primary production in Sakhalin shelf waters Tatyana N. Krupnova Some reasons for resource reduction of Laminaria japonica (Primorye region) Lyudmila N. Luchsheva & Anatoliy I. Botsul Mercury in bottom sediments of the northeastern Okhotsk Sea Pavel A. Luk’yanov, Natalia I. Belogortseva, Alexander A. Bulgakov, Alexander A. Kurika & Olga D. Novikova Lectins and glycosidases from marine macro and micro-organisms of Japan and Okhotsk Seas Boris A. Malyarchuk, Olga A. Radchenko, Miroslava V. Derenko, Andrey G. Lapinski & Leonid L. Solovenchuk PCR-fingerprinting of mitochondrial genome of chum salmon, Oncorhynchus keta Alexander A. Mikheev Chaos and relaxation in dynamics of the pink salmon (Oncorhynchus gorbuscha) returns for two regions Yuri A. Mitrofanov & Larisa N. Lesnikova Fish-culture of Pacific Salmons increases the number of heredity defects Larisa P. Nikolenko Abundance of young halibut along the West Kamchatka shelf in 1982-1992 Sergey A. Nizyaev Living conditions of golden king crab Lithodes aequispina in the Okhotsk Sea and near the Kuril Islands Ludmila A. Pozdnyakova & Alla V. Silina Settlements of Japanese scallop in Reid Pallada Bay (Sea of Japan) Galina M. Pushnikova Features of the Southwest Okhotsk Sea herring Vladimir I. Radchenko & Igor I. Glebov Present state of the Okhotsk herring stock and fisheries outlook Alla V. Silina & Ida I. Ovsyannikova Distribution of the barnacle Balanus rostratus eurostratus near the coasts of Primorye (Sea of Japan) Galina I. Victorovskaya Dependence of urchin Strongylocentrotus intermedius reproduction on water temperature Anatoly F. Volkov, Alexander Y. Efimkin & Valery I. Chuchukalo Feeding habits of Pacific salmon in the Sea of Okhotsk and in the Pacific waters of Kuril Islands in summer 1993 Larisa M. Zverkova & Georgy A. Oktyabrsky Okhotsk Sea walleye pollock stock status Tatyana N. Zvyagintseva, Elena V. Sundukova, Natalia M. Shevchenko & Ludmila A. Elyakova Water soluble polysaccharides of some Far-Eastern seaweeds 3. Biodiversity Program (pdf, 0.2 Mb) A. Biodiversity of island ecosystems and seasides of the North Pacific Larissa A. Gayko Productivity of Japanese scallop Patinopecten yessoensis (IAY) culture in Posieta Bay (Sea of Japan) III APPENDICES 1. List of acronyms 2. List of participants (Document pdf contains 431 pages)
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A summary is presented of research conducted on beach erosion associated with extreme storms and sea level rise. These results were developed by the author and graduate students under sponsorship of the University of Delaware Sea Grant Program. Various shoreline response problems of engineering interest are examined. The basis for the approach is a monotonic equilibrium profile of the form h = Ax2 /3 in which h is water depth at a distance x from the shoreline and A is a scale parameter depending primarily on sediment characteristics and secondarily on wave characteristics. This form is shown to be consistent with uniform wave energy dissipation per unit volume. The dependency of A on sediment size is quantified through laboratory and field data. Quasi-static beach response is examined to represent the effect of sea level rise. Cases considered include natural and seawalled profiles. To represent response to storms of realistic durations, a model is proposed in which the offshore transport is proportional to the "excess" energy dissipation per unit volume. The single rate constant in this model was evaluated based on large scale wave tank tests and confirmed with Hurricane Eloise pre- and post-storm surveys. It is shown that most hurricanes only cause 10% to 25% of the erosion potential associated with the peak storm tide and wave conditions. Additional applications include profile response employing a fairly realistic breaking model in which longshore bars are formed and long-term (500 years) Monte Carlo simulation including the contributions due to sea level rise and random storm occurrences. (PDF has 67 pages.)
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This paper introduces VERTEX, a multi-disciplinary research program dealing with various aspects of particle transport in the upper, high-energy layers (0-2000 m) of the ocean. Background information is presented on hydrography, biological composition of trapped particulates, and major component fluxes observed on a cruise off central California (VERTEX I). Organic C fluxes measured with two trap systems are compared with several other estimates taken from the literature. The intent of this overview paper is to provide a common setting in an economical manner, and avoid undue repetition of background and ancillary information in subsequent publications. (PDF is 43 pages).
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The Channel Islands—sometimes called the Galapagos of North America—are known for their great beauty, rich biodiversity, cultural heritage, and recreational opportunities. In 1980, in recognition of the islands’ importance, the United States Congress established a national park encompassing 5 of California’s Channel Islands (Santa Barbara, Anacapa, Santa Cruz, Santa Rosa, and San Miguel Islands) and waters within 1 nautical mile of the islands. In the same year, Congress declared a national marine sanctuary around each of these islands, including waters up to 6 nautical miles offshore. Approximately 60,000 people visit the Channel Islands each year for aquatic recreation such as fishing, sailing, kayaking, wildlife watching, surfing, and diving. Another 30,000 people visit the islands for hiking, camping, and sightseeing. Dozens of commercial fishing boats based in Santa Barbara, Ventura, Oxnard, and other ports go to the Channel Islands to catch squid, spiny lobster, sea urchin, rockfish, crab, sheephead, flatfish, and sea cucumber, among other species. In the past few decades, advances in fishing technology and the rising number of fishermen, in conjunction with changing ocean conditions and diseases, have contributed to declines in some marine fishes and invertebrates at the Channel Islands. In 1998, citizens from Santa Barbara and Ventura proposed establishment of no-take marine reserves at the Channel Islands, beginning a 4-year process of public meetings, discussions, and scientific analyses. In 2003, the California Fish and Game Commission designated a network of marine protected areas (MPAs) in state waters around the northern Channel Islands. In 2006 and 2007, the National Oceanic and Atmospheric Administration (NOAA) extended the MPAs into the national marine sanctuary’s deeper, federal waters. To determine if the MPAs are protecting marine species and habitats, scientists are monitoring ecological changes. They are studying changes in habitats; abundance and size of species of interest; the ocean food web and ecosystem; and movement of fish and invertebrates from MPAs to surrounding waters. Additionally, scientists are monitoring human activities such as commercial and recreational fisheries, and compliance with MPA regulations. This booklet describes some results from the first 5 years of monitoring the Channel Islands MPAs. Although 5 years is not long enough to determine if the MPAs will accomplish all of their goals, this booklet offers a glimpse of the changes that are beginning to take place and illustrates the types of information that will eventually be used to assess the MPAs’ effectiveness. (PDF contains 24 pages.)
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A recoverable plate impact testing technology has been used for studying the growth mechanisms of mode II crack. The results show that interactions of microcracks ahead of a crack tip cause the crack growth unsteadily. Failure mode transitions of materials were observed. Based on the observations, a discontinuous crack growth model was established. Analysis shows that the shear crack grows unsteady as the growth speed is between the Rayleigh wave speed c(R) and the shear wave speed c(s); however, when the growth speed approaches root 2c(s), the crack grows steadily. The transient microcrack growth makes the main crack speed to jump from subsonic to intersonic and the steady growth of all the sub-cracks leads the main crack to grow stably at an intersonic speed.
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INTRODUCTION: This report summarizes the results of NOAA's sediment toxicity, chemistry, and benthic community studies in the Chesapeake Bay estuary. As part of the National Status and Trends (NS&T) Program, NOAA has conducted studies to determine the spatial extent and severity of chemical contamination and associated adverse biological effects in coastal bays and estuaries of the United States since 1991. Sediment contamination in U.S. coastal areas is a major environmental issue because of its potential toxic effects on biological resources and often, indirectly, on human health. Thus, characterizing and delineating areas of sediment contamination and toxicity and demonstrating their effect(s) on benthic living resources are viewed as important goals of coastal resource management. Benthic community studies have a history of use in regional estuarine monitoring programs and have been shown to be an effective indicator for describing the extent and magnitude of pollution impacts in estuarine ecosystems, as well as for assessing the effectiveness of management actions. Chesapeake Bay is the largest estuarine system in the United States. Including tidal tributaries, the Bay has approximately 18,694 km of shoreline (more than the entire US West Coast). The watershed is over 165,000 km2 (64,000 miles2), and includes portions of six states (Delaware, Maryland, New York, Pennsylvania, Virginia, and West Virginia) and the District of Columbia. The population of the watershed exceeds 15 million people. There are 150 rivers and streams in the Chesapeake drainage basin. Within the watershed, five major rivers - the Susquehanna, Potomac, Rappahannock, York and James - provide almost 90% of the freshwater to the Bay. The Bay receives an equal volume of water from the Atlantic Ocean. In the upper Bay and tributaries, sediments are fine-grained silts and clays. Sediments in the middle Bay are mostly made of silts and clays derived from shoreline erosion. In the lower Bay, by contrast, the sediments are sandy. These particles come from shore erosion and inputs from the Atlantic Ocean. The introduction of European-style agriculture and large scale clearing of the watershed produced massive shifts in sediment dynamics of the Bay watershed. As early as the mid 1700s, some navigable rivers were filled in by sediment and sedimentation caused several colonial seaports to become landlocked. Toxic contaminants enter the Bay via atmospheric deposition, dissolved and particulate runoff from the watershed or direct discharge. While contaminants enter the Bay from several sources, sediments accumulate many toxic contaminants and thus reveal the status of input for these constituents. In the watershed, loading estimates indicate that the major sources of contaminants are point sources, stormwater runoff, atmospheric deposition, and spills. Point sources and urban runoff in the Bay proper contribute large quantities of contaminants. Pesticide inputs to the Bay have not been quantified. Baltimore Harbor and the Elizabeth River remain among the most contaminated areas in the Unites States. In the mainstem, deep sediment core analyses indicate that sediment accumulation rates are 2-10 times higher in the northern Bay than in the middle and lower Bay, and that sedimentation rates are 2-10 times higher than before European settlement throughout the Bay (NOAA 1998). The core samples show a decline in selected PAH compounds over the past several decades, but absolute concentrations are still 1 to 2 orders of magnitude above 'pristine' conditions. Core data also indicate that concentrations of PAHs, PCBs and, organochlorine pesticides do not demonstrate consistent trends over 25 years, but remain 10 times lower than sediments in the tributaries. In contrast, tri-butyl-tin (TBT) concentrations in the deep cores have declined significantly since it=s use was severely restricted. (PDF contains 241 pages)