Age, growth and life history of Klamath River Basin steelhead trout (Onchorhynchus mykiss irideus) as determined from scale analysis

Adult steelhead (Oncorhynchus mykiss irideus) scales were analyzed from eight fall-run, two spring-run, and one winter-run stocks within the Klamath-Trinity River system, from 1981 through 1983, to provide basic information on age, growth, and life history. The higher degree of half-pounder occurrence of upper Klamath River steelhead stocks (86.7 to 100%) compared to Trinity River steelhead stocks (32.0 to 80.0%) was the major life history difference noted in scale analysis. Early life history was similar for all areas sampled with most juveniles (86.4%) remaining in freshwater during the first two years of life before migrating to sea. Repeat spawning ranged from 17.6 to 47.9% for fall-run, 40.0 to 63.6% for spring-run, and 31.1% for winter-run steelhead. Mean length of adults at first spawning was inversely related to percent half-pounder occurrence in each stock. Ages of returning spawners, back calculated lengths at various life stages, and growth information are presented. (PDF contains 22 pages)

A 30-Year History of Tide and Current Measurements in Elkhorn Slough, California

Elkhorn Slough was first exposed to direct tidal forcing from the waters of Monterey Bay with the construction of Moss Landing Harbor in 1946. Elkhorn Slough is located mid-way between Santa Cruz and Monterey close to the head of Monterey Submarine Canyon. It follows a 10 km circuitous path inland from its entrance at Moss Landing Harbor. Today, Elkhorn Slough is a habitat and sanctuary for a wide variety of marine mammals, fish, and seabirds. The Slough also serves as a sink and pathway for various nutrients and pollutants. These attributes are directly or indirectly affected by its circulation and physical properties. Currents, tides and physical properties of Elkhorn Slough have been observed on an irregular basis since 1970. Based on these observations, the physical characteristics of Elkhorn Slough are examined and summarized. Elkhorn Slough is an ebb-dominated estuary and, as a result, the rise and fall of the tides is asymmetric. The fact that lower low water always follows higher high water and the tidal asymmetry produces ebb currents that are stronger than flooding currents. The presence of extensive mud flats and Salicornia marsh contribute to tidal distortion. Tidal distortion also produces several shallow water constituents including the M3, M4, and M6 overtides and the 2MK3 and MK3 compound tides. Tidal elevations and currents are approximately in quadrature; thus, the tides in Elkhorn Slough have some of the characters of a standing wave system. The temperature and salinity of lower Elkhorn Slough waters reflect, to a large extent, the influence of Monterey Bay waters, whereas the temperature and salinity of the waters of the upper Slough (>5 km from the mouth) are more sensitive to local processes. During the summer, temperature and salinity are higher in the upper slough due to local heating and evaporation. Maximum tidal currents in Elkhorn Slough have increased from approximately 75 to 120 cm/s over the past 30 years. This increase in current speed is primarily due to the change in tidal prism which has increased from approximately 2.5 to 6.2 x 106 m3 between 1956 and 1993. The increase in tidal prism is the result of both 3 rapid man-made changes to the Slough, and the continuing process of tidal erosion. Because of the increase in the tidal prism, the currents in Elkhorn Slough exhibit positive feedback, a process with uncertain consequences. [PDF contains 55 pages]

Modified formula of Malus' law for Glan-Taylor polarizing prisms

A simple three-axis model has been developed, which has been successfully applied to the analysis of the light transmittance in spatial incident angle and the simulation of modified formula of Malus' law for Glan-Taylor prisms. Our results indicate that the fluctuations on the cosine squared curve are due to specific misalignments between the axis of the optical system, the optical axis of the prism and the mechanical axis (rotation axis) of prism, which results in the fact that different initial relative location of the to-be-measured-prism in the testing system corresponds to different shape of Malus' law curve. Methods to get absolutely smooth curve are proposed. This analysis is available for other kinds of Glan-type prisms. (C) 2004 Elsevier B.V. All rights reserved.

Effects of international trade of food and feed and human diet shifts on food security and environmental safety: integrating scales

4 p.

The Private Provision of International Impure Public Goods: the Case of Climate Policy

33 p.

Fishes of the Lagunas Encadenadas (Province of Buenos Aires, Argentina), a wetland of international importance

The Lagunas Encadenadas form a large endorheic wetland. The system comprises a chain of five main lagoons (Alsina, Chochico, Del Monte, Del Venado, and Epecuen). During two recent collection trips, 13 species of fish were caught. From the collected material and available data in the literature the following points can be made: The fish fauna of this wetland comprises 18 species from 11 families and six orders. Four species (Cyprinus carpio, Hoplias malabaricus, Loricariichthys anus and Parapimelodus valenciennis) are new records for these water bodies. Fish species diversity decreases from east to west, ie from the most freshwater lagoon (Alsina, with 15 species) to the most saline (Epecuen, 1 species). A similar diversity pattern has been found in zooplankton species.

The avifauna of Laguna Llancanelo (Mendoza, Argentina), a South American wetland of international importance

Laguna Llancanelo is a large (40,000 ha), very shallow (less than 3 m deep), inland saline waterbody, located in southern Mendoza, Argentina. A survey of the avifauna was undertaken during 1983 to 1985; field trips were made mostly to the northeastern and central-western sectors of the lagoon, in the months of April, May, September, October and December. Complementary studies were made by an aerial survey and assessments of terrestrial birds in the surroundings of the lagoon. A total of 64 species in 22 families of birds usually associated with aquatic environments were recorded. The best-represented families of aquatic birds in terms of numbers of species were: Anatidae (13 swans, geese, ducks), Scolopacidae (7 sandpipers and other small waders), Ardeidae (6 herons, bitterns, egrets, Podicipedidae (4 grebes), Rallidae (4 rails, coots) and Charadriidae (4 plovers, lapwings). The most abundant nesting birds on the lagoon were: Black-necked swan Cygnus melancoryphus (824), silvery grebe Podiceps occipitalis (202) and black-crowned night heron Nycticorax nycticorax (100).

Limnology in Sicily: A history of fresh waters surrounded by the sea

The aim of this short article is to trace the history of limnology in Sicily, from the end of the last century up to the present, and pay a little homage to a scientist to whom limnology is deeply indebted: G.E. Hutchinson. Due to its insular and climatic conditions, Sicily is characterised by a drainage network formed by numerous short, torrent-like rivers, and by a few small, natural lakes. The geological characteristics of the island strongly condition the quality of these small waterbodies which generally have surface areas of less than 0.2 km super(2). The earliest observations on Sicilian lentic waters go back more than a century; in particular, at the end of the 19th century, some of the issues regarding the natural lakes had already been brought into focus. Subsequent studies on natural waterbodies concentrated on the geomorphology of landslide lakes or lakes created by the dissolution of the gypsum tableland. However, many of the waterbodies no longer exist because of land reclamation which took place up to the first half of the 1950s. During the last 35 years, there has been a notable increase in limnological publications. In addition, these studies show a more careful and integrated approach to the limnological aspects of waterbodies, compared with the early studies.

A brief history of the scientific study of tropical African inland waters

An account is given of a study of African tropical waters, drawing on the personal experiences of the author. Reviewing developments since 1900, the author examines the way in which research has developed and the influence the changes in the policitcal map of Africa, in particular the change from colonial rule, has had on research.

Application of diatom analysis for the study of the history of the lakes of north-west USSR. [Translation from: Istoriya Ozer; Trudy Vses.Simp.Vilnius p1-7. Vilnius, 1970.]

During late - and post-glacial times lakes played a leading role in the development of the landscape of the North-west European part of USSR. A variety of geographic circumstances created great variegation of natural conditions in lakes and determined the composition of their diatoms. The basic stages of the development of the diatom flora of lakes are linked with general climatic changes. The deepwater regions of large periglacial lakes of the North-west USSR are inhabited by plankton diatoms of the genera Melosira and Cyclotella. Diatom analysis is further applied for the study of the history of the lakes of north-west USSR.