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  • 1
    Type of Medium: Book
    Series Statement: ICES council meeting papers 1975,4
    Language: Undetermined
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  • 2
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    In:  http://aquaticcommons.org/id/eprint/15633 | 8 | 2014-11-13 21:43:17 | 15633
    Publication Date: 2021-07-09
    Description: Fluctuations in primary productivity at two subalpine lakes reveal both meteorological and biological influences. At Castle Lake, California, large-scale climate events such as the El Niño/Southern Oscillation affect total annual production and, combined with human fishing activity, modify the seasonal pattern of productivity. At Lake Tahoe, California-Nevada, local spring weather conditions modulate annual production and its seasonality by determining the depth of mixing and resulting internal nutrient load. Climatic conditions also contribute to deviations from the long-term trend in productivity by increasing the incidence of forest fires and through anomalous external nutrient loads during precipitation extremes. A 3-year cycle in productivity of as yet unknown origin has also been detected at Lake Tahoe.
    Keywords: Atmospheric Sciences ; Ecology ; Limnology ; PACLIM
    Repository Name: AquaDocs
    Type: conference_item
    Format: application/pdf
    Format: application/pdf
    Format: 71-80
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  • 3
    Electronic Resource
    Electronic Resource
    Melbourne, Australia : Blackwell Science Pty
    Lakes & reservoirs 5 (2000), S. 0 
    ISSN: 1440-1770
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geography
    Notes: Inle Lake is situated in the southern part of Shan State in Myanmar. It is the country’s second-largest lake, home to more than 120 000 people and a large bird sanctuary and a major source of hydroelectric power for southern Myanmar. Several distinct environmental problems have arisen in the lake basin. A long-term decrease in lake area has taken place over the last 30 years, probably because of siltation and climate. The drought of the last 2 years in particular has caused a drop in hydroelectric power output, which is affecting southern Myanmar. Many marginal parts of the lake are occupied by elephant grass mats (Saccharum spotaneum L.), known locally as kaing. These mats mature to form solid, floating islands, which are used for a unique form of agriculture but are also an increasing source of pesticide and fertilizer runoff into the lake. Textile cottage industries also abound, and both natural and manufactured dyes are discharged into the lake. Households, including many houses built on stilts in the lake, are a source of garbage and sewage. Livestock breeding also is a source of sewage. Shifting (taungyar) cultivation and village expansion has greatly increased erosion. Dredging is now necessary in many places and water clarity has decreased. The Inle carp (Cyprinus carpio intha), known locally as nga-phane, plays an important role in the food supply, as well as being a cultural symbol of the local Intha people. Nga-phane population abundance is currently low, probably because of changes in water chemistry and decreased clarity in the lake water. Partially because of the perceived potential for tourism, many sectors are now involved in lake rehabilitation and management.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-5117
    Keywords: Lake Tahoe ; primary productivity ; long-term variability ; time series ; cycles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Primary productivity has been measured routinely at Lake Tahoe since 1967, and a number of mechanisms underlying variability in the productivity record have now been identified. A long-term trend due to nutrient loading dominates the series. Seasonality also is prominent, apparently controlled by direct physical factors unrelated to the trophic cascade. A 3-yr cycle has been detected and several possible mechanisms are considered. Irregular fluctuations also are present, caused in part by isolated events (a forest fire) and recurring but variable phenomena (spring mixing). Except possibly for the 3-yr cycle, the known sources of variability appear to operate ‘bottom-up’ through direct physical and chemical effects on the phytoplankton.
    Type of Medium: Electronic Resource
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  • 5
    Publication Date: 2017-02-23
    Description: Environmental perturbation, climate change and international commerce are important drivers for biological invasions. Climate anomalies can further increase levels of habitat disturbance and act synergistically to elevate invasion risk. Herein, we use a historical data set from the upper San Francisco Estuary to provide the first empirical evidence for facilitation of invasions by climate extremes. Invasive zooplankton species did not become established in this estuary until the 1970s when increasing propagule pressure from Asia coincided with extended drought periods. Hydrological management exacerbated the effects of post-1960 droughts and reduced freshwater inflow even further, increasing drought severity and allowing unusually extreme salinity intrusions. Native zooplankton experienced unprecedented conditions of high salinity and intensified benthic grazing, and life history attributes of invasive zooplankton were advantageous enough during droughts to outcompete native species and colonise the system. Extreme climatic events can therefore act synergistically with environmental perturbation to facilitate the establishment of invasive species.
    Type: Article , PeerReviewed
    Format: text
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  • 6
    Publication Date: 2016-12-22
    Description: Zooplankton are an important trophic link and a key food source for many larval fish species in estuarine ecosystems. The present study documents temporal and spatial zooplankton dynamics in Suisun Bay and the Sacramento–San Joaquin Delta—the landward portion of the San Francisco Estuary (California, USA)—over a 37-year period (1972–2008). The zooplankton community experienced major changes in species composition, largely associated with direct and indirect effects of introductions of non-native bivalve and zooplankton species. A major clam invasion and many subsequent changes in zooplankton abundance and composition coincided with an extended drought and accompanying low-flow/high-salinity conditions during 1987–1994. In the downstream mesohaline region, the historically abundant calanoid copepods and rotifers have declined significantly, but their biomass has been compensated to some extent by the introduced cyclopoid Limnothoina tetraspina. The more upstream estuary has also experienced long-term declining biomass trends, particularly of cladocerans and rotifers, although calanoid copepods have increased since the early 1990s due to the introduced Pseudodiaptomus spp. In addition, mysid biomass has dropped significantly throughout the estuary. Shifts in zooplankton species composition have also been accompanied by an observed decrease in mean zooplankton size and an inferred decrease in zooplankton food quality. These changes in the biomass, size, and possibly chemical composition of the zooplankton community imply major alterations in pelagic food web processes, including a drop in prey quantity and quality for foraging fish and an increase in the importance of the microbial food web for higher trophic levels.
    Type: Article , PeerReviewed
    Format: text
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  • 7
    Publication Date: 2017-07-27
    Description: Long-term observations show that fish and plankton populations in the ocean fluctuate in synchrony with large-scale climate patterns, but similar evidence is lacking for estuaries because of shorter observational records. Marine fish and invertebrates have been sampled in San Francisco Bay since 1980 and exhibit large, unexplained population changes including record-high abundances of common species after 1999. Our analysis shows that populations of demersal fish, crabs and shrimp covary with the Pacific Decadal Oscillation (PDO) and North Pacific Gyre Oscillation (NPGO), both of which reversed signs in 1999. A time series model forced by the atmospheric driver of NPGO accounts for two-thirds of the variability in the first principal component of species abundances, and generalized linear models forced by PDO and NPGO account for most of the annual variability of individual species. We infer that synchronous shifts in climate patterns and community variability in San Francisco Bay are related to changes in oceanic wind forcing that modify coastal currents, upwelling intensity, surface temperature, and their influence on recruitment of marine species that utilize estuaries as nursery habitat. Ecological forecasts of estuarine responses to climate change must therefore consider how altered patterns of atmospheric forcing across ocean basins influence coastal oceanography as well as watershed hydrology.
    Type: Article , PeerReviewed
    Format: text
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