APPENDIX Ecoregions of the Oceans Plate 2 (inside back cover) shows regional-scale ecosystem units, or ecoregions, differentiated according to a scheme adapted from Gerhard Schott (1936) as modified by Joerg (1935), James (1936), and Elliott (1954) and using ocean hydrology to indicate the extent of each unit. The units are similar in concept to the continental ecoregions except that the phys- ical characteristics of the water are primary instead of the atmosphere. The map was developed to provide a marine counterpart to the conti- nental ecoregions (Bailey 1989). Understanding the continental systems requires a grasp of the ocean systems that control, through influence on climatic patterns, the continental systems. Two levels or categories of this hierarchy are shown. Of these, the broadest, domains, are based on the major lines of convergence where water masses differing in tempera- ture, salt content, life forms, and color are in contact. Schott recognizes three contrasting types of water, separated by these convergences. Within them, divisions are based largely on the broad natural regions following Dietrich’s (1963) system, summarized in Tables A.1 and A.2. Dietrich’s system was used with similar results by Hayden et al. (1984) in their proposed regionalization of marine environments. This classification takes into account the circulation of the oceans, the temperature and salinity, and indirectly, the presence of major zones of upwelling. The characteristic motion of the surface is emphasized because of its influence on temperature. Salinity is generally higher in areas of higher temperature and, therefore, higher evaporation. Marine organisms are usually more abundant in cold waters, which makes the water appear more green. R.G. Bailey, Ecosystem Geography, DOI 10.1007/978-0-387-89516-1, 203 C Springer Science+Business Media, LLC 2009 204 Appendix. Ecoregions of the Oceans Table A.1. Natural regions of the oceansa Dietrich group and types Ecoregion equivalents B Boreal regions Polar domain (500) Inner boreal (Bi) Inner polar division (510) Outer boreal (Bä) Outer polar division (520) W Westerly drift ocean regions Temperate domain (600) Poleward of oceanic polar front (Wp) Poleward westerlies division (610) Equatorward of polar front (Wä) Equatorward westerlies division (620) R Horse latitude ocean regions (R) Subtropical division (630) High salinity subtropical division (640)b F Jet current regions (F) Jet stream division (650) M Monsoon ocean regions Poleward monsoon (Mp) Poleward monsoon division (660) Tropical domain (700) Tropical monsoon (Mt) Tropical monsoon division (710) High salinity tropical monsoon division (720)b P Trade wind regions With poleward current (Pp) Poleward trades division (730) With westerly current (Pw) Trade winds division (740) With equatorward component (Pä) Equatorward trades division (750) A Equatorial ocean regions (Ä) Equatorial countercurrent division (760) aFrom the Dietrich system (1963). bNot recognized by Dietrich; from Elliott (1954). More details about the classification system as well as detailed descriptions, illustrations, and examples are presented elsewhere (Bailey 1998a). I describe briefly in the following paragraphs the ecoregion units that appear in the legend to the map. Polar Domain At times or during the winter, ice of the Arctic or Antarctic ocean covers the polar domain. These oceans are characterized, in general, by water that is greenish, low in temperature, low in salt content, and rich in plankton. The duration of ice provides a basis for division into (1) an inner polar zone (division) covered by ice for the entire year and (2) an Temperate Domain 205 Table A.2. Definitions and boundaries of the Dietrich system P(Passat in German), persistent westerly setting currents ◦ Pä With 30 equatorward component Pw Predominantly westerly set ◦ Pp With 30 poleward current Ä(Äquator in German), regions of currents directed at times or all year to the east M(Monsun in German), regions of regular current reversal in spring and autumn Mt Low-latitude monsoon areas of little temperature variation Mp Mid- to high (poleward) latitude equivalents of large temperature variations R(Ross in German), at times or all year marked by weak or variable currents F(Freistrahlregionen in German), all-year, geostropically controlled narrow current belts of midlatitude westerly margins of oceans W(Westwind in German), marked by somewhat variable but dominantly east-setting currents all year Wä Equatorward of oceanic polar front (convergence) Wp Poleward of oceanic polar front (convergence) B At times or throughout the year ice covered, in Arctic and Antarctic seas Bi Entire year covered with ice Bä Winter and spring covered with ice outer polar zone (division) where, with a 50% probability, ice is encoun- tered during winter and spring. Temperate Domain The temperate domain comprises the middle latitudes between the pole- ward limits of the tropics and the equatorward limits of pack ice in winter. Currents in this region correspond to wind movements around the subtropical atmospheric high-pressure cells. These are the so-called mixed waters of the middle latitudes. The variable direction of the cur- rent determines the divisions: (1) a poleward westerlies zone (division) with cold water and sea ice that is poleward of the oceanic polar front; (2) an equatorward westerlies zone (division) that has cool water and is equatorward of the oceanic polar front; (3) a subtropical zone (division) with weak currents of variable directions; (4) a high salinity, subtropical division characterized by excess evaporation over precipitation; (5) a jet steam division characterized by strong, narrow currents that exit during 206 Appendix. Ecoregions of the Oceans the entire year as the result of discharge from trade wind regions; and (6) a poleward monsoon division of high latitudes with reversal of current (connected with large annual variations in surface temperature). Tropical Domain The tropical domain is characterized by ocean water that is generally blue, high in temperature, high in salt content, and low in organic forms. It is divided into (1) tropical monsoon with regular reversal of the current system (connected with small annual variations in surface temperature); (2) high salinity tropical monsoon with alternating currents; (3) pole- ward trades with a strong velocity directed toward the poles; (4) trade winds with current moving toward the west; (5) equatorward trades with a strong velocity directed toward the equator, and where currents tend to swing offshore and cold water well up from below; and (6) equatorial countercurrents where currents are directed at times or during the entire year toward the east. Shelf All shallow-shelf areas with depths of 0–200 m are interpreted as shallow variations of the hydrologic zone concerned. A further ecoregional break- down of coastal and shelf areas of the world is presented by Spalding et al. (2007). A controlling factor approach to classification (see Chapter 3) of estuaries in New Zealand is described by Hume et al. (2007). The clas- sification is based on the principle that particular factors are responsible for environmental processes and patterns that are observed at various spatial scales. The classification differentiates estuaries at four levels of detail. The authors propose that the ocean ecoregions presented in this book, which defines regions of homogeneous climate and oceanic water masses at broad scales, provide an appropriate subdivision of estuaries at Level 1 of the classification, a category based on the ocean ecoregion within which it is located. GLOSSARY Glossary Albedo reflectivity of the earth environment, generally measured in percentage of incoming radiation. Alfisols soil order consisting of soils with gray to brown surface horizon, medium to high base supply, and subsurface horizons of clay accumu- lation. Algorithm a sequence of finite mathematical instructions, often used for calculation and data processing. Anadromous going upstream to spawn. Anthropogenic induced or altered by the presence and activities of man. Aridisols soil order consisting of soils with pedogenic horizons, low in organic matter, usually dry. Azonal zonal in a neighboring zone but confined to an extrazonal envi- ronment in a given zone. Bases certain cations in the soil that are also plant nutrients; the most important are cations of calcium, magnesium, potassium, and sodium. Benthic (zone) the ecological region at the lowest level of a body of water such as an ocean or a lake, including the sediment surface and some sub-surface layers. Biodiversity variety of life and its processes, including the variety in genes, species, ecosystems, and the ecological processes that connect everything in ecosystems. Biota plant and animal life of a region. Biome largest recognizable subdivision of the terrestrial ecosystem, including total assemblage of plants and animals. Block-fault produced when normal (near vertical) faults fracture a sec- tion of continental crust. Vertical motion of the resulting blocks, some- times accompanied by tilting, can then lead to high escarpments. 207 208 Glossary These mountains are formed by the earth’s crust being stretched and extended by tensional forces. Boreal forest see tayga. Boroll suborder of soil order Mollisols; includes Mollisols of cold-winter semiarid plants (steppes) or high mountains. Broad-leaved with leaves other than linear in outline; as opposed to needle-leaved or grasslike (graminoid). Brown soil alkaline soil having a thin,