25 resultados para Climatic conditions


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H.J. Andrews Experimental Forest is a 6400 ha forest of Douglas fir, western hemlock, and Pacific silver fir located in, and typical of, the central portion of the western slope of the Cascade mountain range of Oregon. The forest is one of 19 sites in the Long-Term Ecological Research (LTER) program sponsored by the National Science Foundation. ... Because of the scientific significance of Andrews Forest, it is important to investigate the temporal variability of annual and seasonal temperature and precipitation values at the site and identify past times of anomalous climatic conditions. It is also important to establish quantitatively the relationships between the climate of Andrews Forest and that of its surrounding area and, hence, place the climate of Andrews Forest into its regional context.

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A well-documented history of past climatic conditions is needed to understand and resolve some ecological problems, but the existing climatological records are too short to detect long-term climatic variability and changes. Some trees, such as pines, produce annual tree rings with different widths depending on prevailing environmental conditions, such as climate. Tree-ring analysis of long-lived trees can be used to estimate past variations in climate. The principal aim of this study is to reconstruct aridity for the southern portion of the Baja California Peninsula, by means of dendroclimatologic techniques.

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EXTRACT (SEE PDF FOR FULL ABSTRACT): Clipperton Atoll (10°18'N, 109°13'W), lies within the eastern Pacific elongated warm water pool centered at 10°N and is situated at the boundary of the North Equatorial Counter-Current (NECC) and westward-flowing eddy currents moving away from Central America. ... Fifteen coral cores were collected from massive heads of Porites lobata in April 1994 for the purpose of reconstructing oceanographic and climatic conditions at this open ocean site in the eastern Pacific.

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In tropical countries like India, climatic conditions vary in different parts, as a result the breeding of fast growing species such as Catla and silver carps poses considerable problems due to erratic or late monsoon or prolonged dry spell. Hence it is not possible to meet the fish seed requirement of the country. Therefore: to meet the future requirement and to over-come the environmental conditions a Modern carp Hatchery CIFE D-81 was designed. The system provides optimum temperature, silt free clean, cool, highly oxygenated water, low current and continuous removal of metabolites. It has been successfully demonstrated at Rawatbhata (Rajasthan), Badkhal (Haryana), Badbhada (M.P), Guntur and East Godavari District (A.P). Recently a Modern Carp Hatchery was installed in a semi-arid zone, Damdama (Haryana), during 1984, where it has produced record 1.88 crores of fish seed and worked successfully.

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Even though smoke curing is a very elegant method of preserving fish, the resultant products have only a very restricted shelf-life, unless stored under refrigerated conditions. The main source of spoilage is the early setting in of a vigorous growth of moulds. This problem is of a serious nature even in temperate climatic conditions. In full and universal recognition of the gravity of the problem, the FAO conference on herring technology held in September 1950 at Bergen in Norway has recommended the problem of "means of prevention of mould growth in smoked products" for future research study. This note records an interesting observation made at this Laboratory on the inhibitory action of sodium chloride on the development of mould in smoked fishery products.

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Although Sri Lanka is endowed with favourable climatic conditions and resources for breeding and rearing ornamental fish for export, a considerable number of ornamental fish producers as well as exporters have given up the industry within a relatively short period of time. This study was conducted to understand the present status of the industry and to identify the problems that have caused these failures. The study was conducted from March to December in the year 2007 and covered Colombo, Kaluthara, Polonnaruwa, Negombo, Wattala, Rathnapura, Avissawella, Kandy, Kegalle, Padukka, and Gampaha areas, where ornamental fish culture is known to be popular. The survey was carried out by interviewing ornamental fish farmers using a structured questionnaire survey that was designed to elicit the required information. Most (75%) of those surveyed were identified as small scale farmers. A majority (56%) of them used only cement tanks for their culture activities. Only 47% of farmers had proper technical knowledge or training on fish culture while 42% directly supplied their fish products to the expo1iers. The most important constraints identified by the study were as follows: (1) the sale price offish not changing in keeping with the increase in the material costs of production - Feed, cement, sand, transport and labour - in recent years. (2) Difficulty to find export markets for newcomers to enter the export market. (3) Lack of quality brooders and information on the most suitable fish varieties for the different climatic and water conditions in different areas in the country (3) Feed availability and cost. (4) Lack of adequate knowledge and technical support with regard to disease control and water quality management. (5) Difficulty to survive in the off season. (6) Difficulty in obtaining credit for expansion and the lack of sufficient involvement of responsible authorities in overcoming all these identified constraints.

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Ecological study on Kolahy and 'flab estuaries were carried out during 1996-1997. Water and sediment sampling was done seasonally. In order to study the physical and chemical characteristic of the water, various animal fauna from different material niches including planktons and fish from water, benthousi from the sediment , and surface living animal such as Arthropod (Crabs) and Waterbirds were identified. I he result shoved, that water salinity of both estuaries was the same as the general salinity existing its the Persian Gulf water, and its variation is same IN those waters Minimum water salinity in both estuaries are seen during Bahairdan or early winter mooth(Jaa.), which is about 31ppt and Maximum is during .rirldlun.) or summer mouth at about 19 ppt. Dissolved otygen and pH are slime as the general Persian Gulf waters., Dissolve Oxygen being directly associated to temperature and its fluctuation is between 7- Sing/I and pH between 7.5-LS. The animals of both estuaries are almost similar having a sal factory species diversity . The birds of the region are often seasonal migrants , the maximum population of which occurs in winter season and the minimum during summer month. Nam coverage is richer in Tiab than Kolahy estuary, where in Kolahy a signal Mangrove tree is in exigence. 'Ile total coverage of Mangrove forest in Tiab is estimated about -29 hec.Both estuaries are included with in the international Ramsar Convention sites in 1971. Due to national importance of these estuaries inproviding refugee for various birds species and also hinting grounds and access traffic for local fishing vehicles, Actiog as an important access for various inhabitancy living with these area of the Persian Gulf. Due to importance or prawn aquacultur for the economical well being of local inhabitance, these areas provide a suitable grandees for prawn production. I-test statistics show, there are no significant difference among various invertebrate and vertebrate animals. In over all out look 21) phytoplankton genera, 21) zeoplankton genera 17 miafauna and 32 roaerofauna genera , 11 different species Carcineacearions and 119 species of walerbirds were identified with in the Tiab and Kolahy estuariesregioos. The X statistic show that the animal density is directly associated to season. Where density of miofauna and maerofauna in both estuaries are in maiticrourn during summer and the minimums existing during the winter season. In addition the bentic invertebrate population density in closlly association to birds population density since , the later, feeds on the former animals. Where the increasing in bird population density during the winter season, the bentic invertebrate animal population density decreases. The over all trend of animal population density in winter tend to increased towards the summer seasons, which this is due to climatic conditions of the region. The bird population on the contrary to other animals of both estuaries tend to increase from summer towards the winter seasons and which this bird population density is in maximum in winter with in the region.

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Environmental changes are some of the factors that affect fisheries and biological characteristics of fishes. The African catfish Clarias gariepinus (Burchell, 1822) has biological characteristics that enable it to persist under various stressful environmental conditions. However, few studies have examined how the African catfish responds to conditions created by a changing climate. The study examined some of the fishery and biological characteristics of African catfish in Lake Wamala (Uganda) to provide an understanding of their response to changing climatic conditions using data for the period 1950 - 2013. Temperature around the lake increased by 0.02ºC/year since 1980, commensurate with the regional trend, while rainfall was above average since 1996, except in 2004 and 2008. Lake depth was strongly positively correlated with rainfall (r =0.83, n= 6, p<0.05) up to 2000, after which, lake depth decreased amidst increase in rainfall. The contribution of African catfish increased from 20% to 85% and 17% to 78% respectively to commercial and experimental catches respectively between 1975 and 2013 despite the decrease in lake depth. The modal total length, condition factor, food, and fecundity did not change. Only size at first maturity decreased from 37.5 to 30 cm TL in females and 39.5 to 34.2 cm TL in males between 1999/2000 and 2012/2013. The biological characteristics of the African catfish were comparable with those of the same species in other lakes and remained relatively stable. The results suggested that the African catfish has the capacity to persist and/or adjust appropriately under conditions created by climate variability and change, and if properly managed, can sustain the fisheries of Lake Wamala.

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EXTRACT (SEE PDF FOR FULL ABSTRACT): Tree-ring records from foxtail pine (Pinus balfouriana) and western juniper (Juniperus occidentalis) growing near tree line in the eastern Sierra Nevada, California, show strong correlations with summer temperature and winter precipitation. Response surfaces portraying tree growth as a function of summer temperature and winter precipitation indicate a strong interaction between these variables in controlling growth. ... Above average growth for both foxtail pine and western juniper from AD 1480 to 1570 can be interpreted as indicating an extended period of warm, moist conditions unequalled during the 20th century.

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Historical sources of the late-18th and 19th centuries were searched for information on coastal weather conditions in Southern California. Relatively calm winters until 1828 were followed by unusually stormy winters from about 1829 to 1839. Later periods were again predominantly calm, with notable exceptions related to the ENSO events of 1845 and 1878. Following decreases through the stormy 1830s, sizes of kelp forests appear to have rebounded in the 1840s. ENSO occurrences and eruption of the volcano Cosiguina in 1835 are likely causes for changing wind patterns. Our results link the unique AD 1840 Macoma leptonoidea pelecypod shell layer in laminated Santa Barbara Basin sediment ("Macoma event") to abruptly changing oceanographic and weather patterns.