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Coastal Flood Defences - Groynes
Coastal Flood Defences - Groynes Coastal flood defences are key to protecting our coasts against flooding, which is when normally dry, low lying flat land is inundated by sea water. Hard engineering methods are forms of coastal flood defences which mitigate the risk of flooding and coastal erosion and the consequential effects. Hard Engineering Hard engineering methods are often used as a temporary measure to protect against coastal flooding as they are costly and only last for a relatively short amount of time before they require maintenance. However, they are very effective at protecting the coastline in the short-term as they are immediately effective as opposed to some longer term soft engineering methods. But they are often intrusive and can cause issues elsewhere at other areas along the coastline. Groynes are low lying wood or concrete structures which are situated out to sea from the shore. They are designed to trap sediment, dissipate wave energy and restrict the transfer of sediment away from the beach through long shore drift. Longshore drift is caused when prevailing winds blow waves across the shore at an angle which carries sediment along the beach.Groynes prevent this process and therefore, slow the process of erosion at the shore. They can also be permeable or impermeable, permeable groynes allow some sediment to pass through and some longshore drift to take place. However, impermeable groynes are solid and prevent the transfer of any sediment. Advantages and Disadvantages +Groynes are easy to construct. +They have long term durability and are low maintenance. +They reduce the need for the beach to be maintained through beach nourishment and the recycling of sand. -
Basic Concepts in Oceanography
Chapter 1 XA0101461 BASIC CONCEPTS IN OCEANOGRAPHY L.F. SMALL College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, Oregon, United States of America Abstract Basic concepts in oceanography include major wind patterns that drive ocean currents, and the effects that the earth's rotation, positions of land masses, and temperature and salinity have on oceanic circulation and hence global distribution of radioactivity. Special attention is given to coastal and near-coastal processes such as upwelling, tidal effects, and small-scale processes, as radionuclide distributions are currently most associated with coastal regions. 1.1. INTRODUCTION Introductory information on ocean currents, on ocean and coastal processes, and on major systems that drive the ocean currents are important to an understanding of the temporal and spatial distributions of radionuclides in the world ocean. 1.2. GLOBAL PROCESSES 1.2.1 Global Wind Patterns and Ocean Currents The wind systems that drive aerosols and atmospheric radioactivity around the globe eventually deposit a lot of those materials in the oceans or in rivers. The winds also are largely responsible for driving the surface circulation of the world ocean, and thus help redistribute materials over the ocean's surface. The major wind systems are the Trade Winds in equatorial latitudes, and the Westerly Wind Systems that drive circulation in the north and south temperate and sub-polar regions (Fig. 1). It is no surprise that major circulations of surface currents have basically the same patterns as the winds that drive them (Fig. 2). Note that the Trade Wind System drives an Equatorial Current-Countercurrent system, for example. -
Mapping Current and Future Priorities
Mapping Current and Future Priorities for Coral Restoration and Adaptation Programs International Coral Reef Initiative (ICRI) Ad Hoc Committee on Reef Restoration 2019 Interim Report This report was prepared by James Cook University, funded by the Australian Institute for Marine Science on behalf of the ICRI Secretariat nations Australia, Indonesia and Monaco. Suggested Citation: McLeod IM, Newlands M, Hein M, Boström-Einarsson L, Banaszak A, Grimsditch G, Mohammed A, Mead D, Pioch S, Thornton H, Shaver E, Souter D, Staub F. (2019). Mapping Current and Future Priorities for Coral Restoration and Adaptation Programs: International Coral Reef Initiative Ad Hoc Committee on Reef Restoration 2019 Interim Report. 44 pages. Available at icriforum.org Acknowledgements The ICRI ad hoc committee on reef restoration are thanked and acknowledged for their support and collaboration throughout the process as are The International Coral Reef Initiative (ICRI) Secretariat, Australian Institute of Marine Science (AIMS) and TropWATER, James Cook University. The committee held monthly meetings in the second half of 2019 to review the draft methodology for the analysis and subsequently to review the drafts of the report summarising the results. Professor Karen Hussey and several members of the ad hoc committee provided expert peer review. Research support was provided by Melusine Martin and Alysha Wincen. Advisory Committee (ICRI Ad hoc committee on reef restoration) Ahmed Mohamed (UN Environment), Anastazia Banaszak (International Coral Reef Society), -
1 the Influence of Groyne Fields and Other Hard Defences on the Shoreline Configuration
1 The Influence of Groyne Fields and Other Hard Defences on the Shoreline Configuration 2 of Soft Cliff Coastlines 3 4 Sally Brown1*, Max Barton1, Robert J Nicholls1 5 6 1. Faculty of Engineering and the Environment, University of Southampton, 7 University Road, Highfield, Southampton, UK. S017 1BJ. 8 9 * Sally Brown ([email protected], Telephone: +44(0)2380 594796). 10 11 Abstract: Building defences, such as groynes, on eroding soft cliff coastlines alters the 12 sediment budget, changing the shoreline configuration adjacent to defences. On the 13 down-drift side, the coastline is set-back. This is often believed to be caused by increased 14 erosion via the ‘terminal groyne effect’, resulting in rapid land loss. This paper examines 15 whether the terminal groyne effect always occurs down-drift post defence construction 16 (i.e. whether or not the retreat rate increases down-drift) through case study analysis. 17 18 Nine cases were analysed at Holderness and Christchurch Bay, England. Seven out of 19 nine sites experienced an increase in down-drift retreat rates. For the two remaining sites, 20 retreat rates remained constant after construction, probably as a sediment deficit already 21 existed prior to construction or as sediment movement was restricted further down-drift. 22 For these two sites, a set-back still evolved, leading to the erroneous perception that a 23 terminal groyne effect had developed. Additionally, seven of the nine sites developed a 24 set back up-drift of the initial groyne, leading to the defended sections of coast acting as 1 25 a hard headland, inhabiting long-shore drift. -
Marine Forecasting at TAFB [email protected]
Marine Forecasting at TAFB [email protected] 1 Waves 101 Concepts and basic equations 2 Have an overall understanding of the wave forecasting challenge • Wave growth • Wave spectra • Swell propagation • Swell decay • Deep water waves • Shallow water waves 3 Wave Concepts • Waves form by the stress induced on the ocean surface by physical wind contact with water • Begin with capillary waves with gradual growth dependent on conditions • Wave decay process begins immediately as waves exit wind generation area…a.k.a. “fetch” area 4 5 Wave Growth There are three basic components to wave growth: • Wind speed • Fetch length • Duration Wave growth is limited by either fetch length or duration 6 Fully Developed Sea • When wave growth has reached a maximum height for a given wind speed, fetch and duration of wind. • A sea for which the input of energy to the waves from the local wind is in balance with the transfer of energy among the different wave components, and with the dissipation of energy by wave breaking - AMS. 7 Fetches 8 Dynamic Fetch 9 Wave Growth Nomogram 10 Calculate Wave H and T • What can we determine for wave characteristics from the following scenario? • 40 kt wind blows for 24 hours across a 150 nm fetch area? • Using the wave nomogram – start on left vertical axis at 40 kt • Move forward in time to the right until you reach either 24 hours or 150 nm of fetch • What is limiting factor? Fetch length or time? • Nomogram yields 18.7 ft @ 9.6 sec 11 Wave Growth Nomogram 12 Wave Dimensions • C=Wave Celerity • L=Wave Length • -
Coastal Upwelling Revisited: Ekman, Bakun, and Improved 10.1029/2018JC014187 Upwelling Indices for the U.S
Journal of Geophysical Research: Oceans RESEARCH ARTICLE Coastal Upwelling Revisited: Ekman, Bakun, and Improved 10.1029/2018JC014187 Upwelling Indices for the U.S. West Coast Key Points: Michael G. Jacox1,2 , Christopher A. Edwards3 , Elliott L. Hazen1 , and Steven J. Bograd1 • New upwelling indices are presented – for the U.S. West Coast (31 47°N) to 1NOAA Southwest Fisheries Science Center, Monterey, CA, USA, 2NOAA Earth System Research Laboratory, Boulder, CO, address shortcomings in historical 3 indices USA, University of California, Santa Cruz, CA, USA • The Coastal Upwelling Transport Index (CUTI) estimates vertical volume transport (i.e., Abstract Coastal upwelling is responsible for thriving marine ecosystems and fisheries that are upwelling/downwelling) disproportionately productive relative to their surface area, particularly in the world’s major eastern • The Biologically Effective Upwelling ’ Transport Index (BEUTI) estimates boundary upwelling systems. Along oceanic eastern boundaries, equatorward wind stress and the Earth s vertical nitrate flux rotation combine to drive a near-surface layer of water offshore, a process called Ekman transport. Similarly, positive wind stress curl drives divergence in the surface Ekman layer and consequently upwelling from Supporting Information: below, a process known as Ekman suction. In both cases, displaced water is replaced by upwelling of relatively • Supporting Information S1 nutrient-rich water from below, which stimulates the growth of microscopic phytoplankton that form the base of the marine food web. Ekman theory is foundational and underlies the calculation of upwelling indices Correspondence to: such as the “Bakun Index” that are ubiquitous in eastern boundary upwelling system studies. While generally M. G. Jacox, fi [email protected] valuable rst-order descriptions, these indices and their underlying theory provide an incomplete picture of coastal upwelling. -
Fisheries Research 213 (2019) 219–225
Fisheries Research 213 (2019) 219–225 Contents lists available at ScienceDirect Fisheries Research journal homepage: www.elsevier.com/locate/fishres Contrasting river migrations of Common Snook between two Florida rivers using acoustic telemetry T ⁎ R.E Bouceka, , A.A. Trotterb, D.A. Blewettc, J.L. Ritchb, R. Santosd, P.W. Stevensb, J.A. Massied, J. Rehaged a Bonefish and Tarpon Trust, Florida Keys Initiative Marathon Florida, 33050, United States b Florida Fish and Wildlife Conservation Commission, Florida Fish and Wildlife Research Institute, 100 8th Ave. Southeast, St Petersburg, FL, 33701, United States c Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute, Charlotte Harbor Field Laboratory, 585 Prineville Street, Port Charlotte, FL, 33954, United States d Earth and Environmental Sciences, Florida International University, 11200 SW 8th street, AHC5 389, Miami, Florida, 33199, United States ARTICLE INFO ABSTRACT Handled by George A. Rose The widespread use of electronic tags allows us to ask new questions regarding how and why animal movements Keywords: vary across ecosystems. Common Snook (Centropomus undecimalis) is a tropical estuarine sportfish that have been Spawning migration well studied throughout the state of Florida, including multiple acoustic telemetry studies. Here, we ask; do the Common snook spawning behaviors of Common Snook vary across two Florida coastal rivers that differ considerably along a Everglades national park gradient of anthropogenic change? We tracked Common Snook migrations toward and away from spawning sites Caloosahatchee river using acoustic telemetry in the Shark River (U.S.), and compared those migrations with results from a previously Acoustic telemetry, published Common Snook tracking study in the Caloosahatchee River. -
Nh-Connect-The-Coast-Report.Pdf
Connect THE Coast LINKING WILDLIFE ACROSS NEW HAMPSHIRE’S SEACOAST AND BEYOND Final Report: 10/31/2019 Authors: Peter Steckler and Dea Brickner-Wood Connect THE Coast LINKING WILDLIFE ACROSS NEW HAMPSHIRE’S SEACOAST AND BEYOND FINAL REPORT 10/31/2019 Authors Peter Steckler GIS & Conservation Project Manager The Nature Conservancy, New Hampshire Dea Brickner-Wood Coordinator Great Bay Resource Protection Partnership Cite plan as: Steckler, P and Brickner-Wood, D. 2019. Connect The Coast final report. The Nature Conservancy and the Great Bay Resource Protection Partnership. Concord, NH. Cover: Map of New Hampshire’s Coastal watershed, created by The Nature Conservancy. Table of Contents Acknowledgements ................................................................................................................................ i Executive Summary ............................................................................................................................... ii 1. Introduction .................................................................................................................................... 1 Project Area .............................................................................................................................. 1 Conservation Context ............................................................................................................... 3 Historic Context of Land Use in the Coastal Watershed ........................................................ 4 Current Connectivity Challenges -
Upwelling As a Source of Nutrients for the Great Barrier Reef Ecosystems: a Solution to Darwin's Question?
Vol. 8: 257-269, 1982 MARINE ECOLOGY - PROGRESS SERIES Published May 28 Mar. Ecol. Prog. Ser. / I Upwelling as a Source of Nutrients for the Great Barrier Reef Ecosystems: A Solution to Darwin's Question? John C. Andrews and Patrick Gentien Australian Institute of Marine Science, Townsville 4810, Queensland, Australia ABSTRACT: The Great Barrier Reef shelf ecosystem is examined for nutrient enrichment from within the seasonal thermocline of the adjacent Coral Sea using moored current and temperature recorders and chemical data from a year of hydrology cruises at 3 to 5 wk intervals. The East Australian Current is found to pulsate in strength over the continental slope with a period near 90 d and to pump cold, saline, nutrient rich water up the slope to the shelf break. The nutrients are then pumped inshore in a bottom Ekman layer forced by periodic reversals in the longshore wind component. The period of this cycle is 12 to 25 d in summer (30 d year round average) and the bottom surges have an alternating onshore- offshore speed up to 10 cm S-'. Upwelling intrusions tend to be confined near the bottom and phytoplankton development quickly takes place inshore of the shelf break. There are return surface flows which preserve the mass budget and carry silicate rich Lagoon water offshore while nitrogen rich shelf break water is carried onshore. Upwelling intrusions penetrate across the entire zone of reefs, but rarely into the Lagoon. Nutrition is del~veredout of the shelf thermocline to the living coral of reefs by localised upwelling induced by the reefs. -
A Laboratory Model of Thermocline Depth and Exchange Fluxes Across Circumpolar Fronts*
656 JOURNAL OF PHYSICAL OCEANOGRAPHY VOLUME 34 A Laboratory Model of Thermocline Depth and Exchange Fluxes across Circumpolar Fronts* CLAUDIA CENEDESE Physical Oceanography Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts JOHN MARSHALL Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts J. A. WHITEHEAD Physical Oceanography Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts (Manuscript received 6 January 2003, in ®nal form 7 July 2003) ABSTRACT A laboratory experiment has been constructed to investigate the possibility that the equilibrium depth of a circumpolar front is set by a balance between the rate at which potential energy is created by mechanical and buoyancy forcing and the rate at which it is released by eddies. In a rotating cylindrical tank, the combined action of mechanical and buoyancy forcing builds a strati®cation, creating a large-scale front. At equilibrium, the depth of penetration and strength of the current are then determined by the balance between eddy transport and sources and sinks associated with imposed patterns of Ekman pumping and buoyancy ¯uxes. It is found 2 that the depth of penetration and transport of the front scale like Ï[( fwe)/g9]L and weL , respectively, where we is the Ekman pumping, g9 is the reduced gravity across the front, f is the Coriolis parameter, and L is the width scale of the front. Last, the implications of this study for understanding those processes that set the strati®cation and transport of the Antarctic Circumpolar Current (ACC) are discussed. If the laboratory results scale up to the ACC, they suggest a maximum thermocline depth of approximately h 5 2 km, a zonal current velocity of 4.6 cm s21, and a transport T 5 150 Sv (1 Sv [ 106 m3 s 21), not dissimilar to what is observed. -
Coastal Upwelling in the Eastern Gulf of California
OCEANOLOGICA ACTA · VOL. 23 – N° 6 Coastal upwelling in the eastern Gulf of California Salvador-Emilio LLUCH-COTA * Centro de Investigaciones Biolo´gicas del Noroeste, S.C. PO Box 128 La Paz, BCS, Me´xico 23000 Received 11 May 1999; revised 8 December 1999; accepted 13 December 1999 Abstract – Understanding and quantifying upwelling is of great importance for marine resource management. Direct measurement of this process is extremely difficult and observed time-series do not exist. However, proxies are commonly derived from different data; most commonly wind-derived. A local wind-derived coastal upwelling index (CUI) is reported for the period 1970–1996 and is considered representative for the eastern central Gulf of California, an important fishing area where no proxies exist. The index is well related to pigment concentration distribution, surface water temperature, and population dynamics of important fish resources over the seasonal time-scale. There is a biological response to ENSO activity not reflected by this index, indicating that improvement of biological enrichment forecasting also requires water column structure input. A clearly increasing seasonal amplitude signal is detected in the coastal upwelling index and sea surface temperature since the mid 1970s. Understanding the nature of these long-term trends, the incorporation of remote tropical ocean signals into the enrichment proxy, the dynamics of atmosphere and ocean, and the biological responses are major challenges to the proper management of fish resources in the Gulf of California. upwelling / Gulf of California / seasonality / climate change Re´sume´–Upwelling coˆtier dans l’est du golfe de Californie. Comprendre et e´valuer le phe´nome`ne d’upwelling est tre`s important pour la gestion des ressources marines. -
Water Life: Riffles and Pools Stream Ecosystems Provide a Habitat Or
Water Life: Riffles and Pools Stream ecosystems provide a habitat or natural environment for many diverse aquatic organisms and plants. A deeper look indicates each stream has a distinctive anatomy as each is composed of a series of pools, riffles and runs. Pools: An area of the stream characterized by deep depths and slow current. Pools are typically created by the vertical force of water falling down over logs or boulders. The movement of the water carves a deeper indentation in the stream bed. Pools are important because they can provide depth and still water. Riffles: An area of stream characterized by shallow depths with fast, turbulent water. The riffles are short segments of the stream where water flow is agitated by rocks. The rocky Adapted from: bottom provides protection from predators, food http://share3.esd105.wednet.edu/rsandelin/ees/Resources/Flowing%20water%20concepts.htm deposition and shelter. Riffle depths vary depending upon stream size, but can be as shallow as 1 inch or deep as 1 meter. The turbulence and stream flow results in high dissolved oxygen concentration. Run: An area of stream characterized by moderate current, continuous surface and depths greater than riffles. Runs are stretches of the stream downstream of pools and riffles where stream flow and current are moderate. The smooth surface allows for light to penetrate. Microhabitats: Habitats are the natural environment in which an organism lives. The distinguishing abiotic conditions of riffles, pools and runs result in specialized environments that are known as microhabitats. The abiotic conditions (dissolved oxygen, turbidity, light and temperature) of these microhabitats can influence which aquatic species can survive and reproduce at that given location and time.