scholarly journals Responses of Rotifer Community to Microhabitat Changes Caused by Summer-Concentrated Rainfall in a Shallow Reservoir, South Korea

Diversity ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 113 ◽  
Author(s):  
Jong-Yun Choi ◽  
Seong-Ki Kim
Keyword(s):  
Water Surface ◽  
Habitat Structure ◽  
Submerged Macrophytes ◽  
Empirical Studies ◽  
Lepomis Macrochirus ◽  
Summer Rainfall ◽  
Annual Rainfall ◽  
Rotifer Community ◽  
Microhabitat Structure ◽  
Floating Macrophytes

Empirical studies suggest that the structural heterogeneity of aquatic ecosystem microhabitat is determined by the diversity and abundance of macrophytes. However, excessive accumulation of free-floating macrophytes on the water surface can reduce the biomass of submerged macrophytes, resulting in a relatively simplified habitat structure. We hypothesized that heavy summer rainfall disrupts the growth of free-floating macrophytes covering much of the Jangcheok Reservoir’s water surface, thereby resulting in a more complex habitat structure by allowing development of a more diverse of macrophytic community. We divided long-term (2008–2017) monitoring data (rainfall, macrophytes, and rotifers) into two groups: Rainy and Dry years, corresponding to years with annual rainfall higher and lower than the total annual average, respectively. We found that summer densities of rotifers fell sharply in Rainy years, but increased continuously in Dry years. This trend resulted in greater autumn densities in Rainy relative to Dry years, which we attributed to changes in habitat related to differential macrophyte development. Moderate disturbance of the water surface caused by high summer rainfall can promote growth of submerged macrophytes by creating large areas of open water and therefore a more complex autumnal microhabitat structure, resulting in seasonal variations in rotifer community structures and populations. Moreover, a highly complex microhabitat structure restricts foraging activity of fish (i.e., Lepomis macrochirus) that prey on rotifers. Based on these findings, we suggest that summer-concentrated rainfall plays an important role in supporting the density and species diversity of rotifers.

Interlake variation in growth and size structure of bluegill (Lepomis macrochirus): inverse analysis of an individual-based model

1998 ◽  
Vol 55 (2) ◽  
pp. 387-396 ◽  
Author(s):  
Nathan P Nibbelink ◽  
Stephen R Carpenter
Keyword(s):  
Predation Risk ◽  
Food Availability ◽  
Inverse Modeling ◽  
Habitat Structure ◽  
Size Structure ◽  
Lepomis Macrochirus ◽  
Habitat Choice ◽  
Selective Predation ◽  
Free Parameters ◽  
Contrasting Habitats

Habitat structure alters food availability and predation risk, thereby directly affecting growth, mortality, and size structure of fish populations. Size structure has often been used to infer patterns of resource abundance and predation. However, food availability and predation risk in contrasting habitats have proven difficult to measure in the field. We use an inverse modeling approach to estimate food availability and habitat choice parameters from changes in length distributions of bluegill (Lepomis macrochirus). The model suggests that dynamics of bluegill length distributions primarily reflect food availability and habitat choice. Bluegill behavior minimized effects of size-selective predation on size structure. Parameters for food availability and habitat choice were correlated. It was therefore not possible to attain unique estimates of food availability and habitat selection when both were free parameters. However, when one parameter was estimated independently, the other could be identified. In five Wisconsin lakes, seining studies were used to estimate the size at which bluegill switched from littoral to pelagic habitats. Using this measure of switch size in the model, we estimated food availability for bluegill in each lake. These estimates were positively correlated with observed growth (r2 = 0.91), demonstrating the model's ability to estimate food availability.

Invasive Aquatic Species

2018 ◽  
pp. 338-358 ◽  
Author(s):  
Julie A. Coetzee ◽  
Martin P. Hill ◽  
Andreas Hussner ◽  
Ana L. Nunes ◽  
Olaf L.F. Weyl
Keyword(s):  
Northern Hemisphere ◽  
Native Species ◽  
Submerged Macrophytes ◽  
Economic Impacts ◽  
Freshwater Ecosystems ◽  
Aquatic Species ◽  
Anthropogenic Influences ◽  
Freshwater Invasions ◽  
Geographical Bias ◽  
Floating Macrophytes

Freshwater ecosystems are particularly susceptible to invasions by invasive non-native species (INNS) across a range of taxa, largely as a consequence of anthropogenic influences on these systems, with a number of ecological and socio-economic impacts. This chapter reviews freshwater invasive non-native species across the globe, focusing on fishes, invertebrates, floating macrophytes, and submerged macrophytes emphasising the knowledge gaps in particular that have resulted in biases inherent in assessments of freshwater invasions. These include an ecological bias because the majority of studies focus on terrestrial invasions; a geographical bias as most studies are focused on temperate northern hemisphere systems; and a taxon bias where fish invasions, populate the literature. This chapter highlights some of the approaches needed to survey, monitor, and manage INNS.

Photosynthetic Responses of Three Codominant Species from the North-western Sonoran Desert - a C3 Deciduous Sub-shrub, a C4 Deciduous Bunchgrass, and a CAM Evergreen Leaf Succulent

1997 ◽  
Vol 24 (6) ◽  
pp. 787 ◽  
Author(s):  
Park S. Nobel ◽  
Hehui Zhang
Keyword(s):  
Leaf Area ◽  
Sonoran Desert ◽  
Summer Rainfall ◽  
Productivity Index ◽  
Annual Rainfall ◽  
Photon Flux ◽  
Co2 Uptake ◽  
The North ◽  
Net Co2 Uptake ◽  
North Western

To investigate seasonal and annual influences of environmental conditions on leaf net CO2 uptake (A), three codominant species from the north-western Sonoran Desert differing in photosynthetic pathway and leaf phenology were examined: the C3 deciduous sub-shrub Encelia farinosa, the C4 deciduous bunchgrass Pleuraphis rigida, and the CAM evergreen leaf succulent Agave deserti. To allow interspecific comparisons and to predict field responses from 1974 through 1995, an environmental productivity index (EPI) model previously developed for CAM plants was used, which scaled the responses of A to water, temperature, and photosynthetic photon flux (PPF) over 24-h periods to individual dimensionless values. The net CO2 uptake predicted using the EPI approach agreed well with field measurements. Agave deserti was the most drought-tolerant and E. farinosa was the least; the optimum day/night air temperatures and the PPF requirement for A were highest for P. rigida and lowest for A. deserti. For 1974 through 1995, daily EPI averaged over a year was highest for E. farinosa, indicating that it operates closest to its photosynthetic optimum. However, the predicted A was highest for P. rigida. Variations in A were annually bimodal, with the greatest differences among the three species in wet years. Afor all three species increased linearly as annual rainfall increased. Leaf area per plant for E. farinosa was highest in the winter and early spring and did not respond appreciably to summer rainfall; leaf area for P. rigida was also highest in the winter. For the evergreen A. deserti, which based on ground cover is the dominant species at the field site, new leaves unfolded in response to both winter and summer rainfall but most photosynthetic area was contributed by older leaves, leading to the highest annual plant net CO2 uptake.

scholarly journals Interactions between different biological forms of aquatic macrophytes in a eutrophic tropical reservoir in Northeastern Brazil

2017 ◽  
Vol 65 (3) ◽  
pp. 1095 ◽  
Author(s):  
Thainá Alves Lycarião ◽  
Ênio Wocyli Dantas
Keyword(s):  
Aquatic Plants ◽  
Hydrological Cycle ◽  
Submerged Macrophytes ◽  
Correlation Coefficients ◽  
Dry Weight ◽  
Dry Season ◽  
Northeastern Brazil ◽  
Tropical Reservoir ◽  
Emergent Plants ◽  
Floating Macrophytes

The aquatic plants and biological processes have different interactions and their knowledge may contribute to the understanding of environmental dynamics in wetlands. The aim of this study was to report the type of interactions that different biological forms of macrophytes stand in the eutrophic tropical reservoir of Penha reservoir, Northeastern Brazil. Data collection was captured every two months from October 2009 to October 2010, considering the hydrological cycle in one-year period. For this, twelve perpendicular transects (separated by 10 m) at the reservoir’s water edge were defined; each transect had two plots of 625 cm² (25 x 25 cm, separated by one meter) from which samples were obtained. Plants were collected and transported in identified plastic bags for subsequent quantification of the dry weight biomass; additionally, pressed samples were made in the field for identification purposes. The relative interaction index (RII) was used to identify the existence of positive and/or negative interactions between the biomass of the biological forms of aquatic plants. Student’s t-tests were used to analyze variations in the abiotic data and biomass over time, and to determine differences between the dry and rainy seasons. Pearson and Spearman correlation coefficients were calculated to determine correlations between the biological forms and the biomass of the macrophytes, as well as environmental variables and RII. In the dry season, the environment was mainly composed of floating macrophytes (1 013.98 g/m²), with mats of submerged macrophytes (98.18 g/m²) that demonstrated a range of positive (RII= 1.0) to negative (RII= -0.2) interactions. The biomass of emergent macrophytes increased throughout the dry season (4.87 to 106.91 g/m²) due to the nurse plant effect that served as a substratum (RII= 1.0). During the rainy season the biomass of submerged macrophytes was reduced by 97 % due to direct and indirect relationships (RII= -1.0) to other macrophytes. Rainfall and emergent plants contributed to a reduction in the biomass of floating macrophytes (19.16 g/m²). The emergence of a third group of plants (emergent) lead floating plants to occupy other areas and excluded submerged plants. Overall, the interactions among plants within ecosystems were not definite due to stand composition and seasonality.

scholarly journals Simple relationships to predict attributes of fish assemblages in patches of submerged macrophytes

2008 ◽  
Vol 6 (4) ◽  
pp. 543-550 ◽  
Author(s):  
Fernando Mayer Pelicice ◽  
Sidinei Magela Thomaz ◽  
Angelo Antonio Agostinho
Keyword(s):  
Habitat Structure ◽  
Fish Assemblages ◽  
Plant Biomass ◽  
Submerged Macrophytes ◽  
Fish Density ◽  
Aquatic Biodiversity ◽  
Morphological Differences ◽  
Highly Correlated ◽  
Biomass Plant ◽  
Throw Trap

Submerged macrophytes play an important role in structuring habitats and, therefore, in determining patterns of aquatic biodiversity. Because these plants are widespread in shallow areas of many Neotropical reservoirs, the present work investigated if variables related to habitat structure, measured in patches of submerged macrophytes (Egeria densa and E. najas), can be used to predict fish assemblage attributes (fish density and species richness). Based on patch characteristics at fine spatial extents (macrophyte patches within reservoir arms), we considered plant biomass, volume and proportional volume (i.e. percentage of macrophyte volume in the water column) as potential predictors. Fish and macrophytes were sampled with a 1-m² throw trap in littoral habitats of Rosana Reservoir, Paranapanema River, and simple correlation analyses were performed. Fish richness and abundance were highly correlated with all variables (R = 0.53 to 0.90), a relationship consistently observed in all sites. When compared to biomass, plant volume and proportional volume did not yield stronger correlations. We observed stronger correlations when E. densa and E. najas patches were analyzed separately (mono-specificity), probably because particular effects of each macrophyte on habitat structuring were removed (e.g. unnoticed morphological differences or unknown effects on habitat quality). The high R values observed in all pairwise relationships are uncommon in ecological studies, highlighting the predictive potential of variables related to habitat structure. These results suggest that, at small spatial extents, macrophyte biomass may represent an interesting predictor of fish density and richness in reservoirs with extensive colonization of submerged plants.

Irrigation in semi-arid regions

1967 ◽  
Vol 5 (4) ◽  
pp. 139-143 ◽  
Author(s):  
E. R. Hoare
Keyword(s):  
Water Surface ◽  
Arid Regions ◽  
Living Conditions ◽  
Annual Rainfall ◽  
Land Area ◽  
Semi Arid

A land area can be considered semi-arid if it has an annual rainfall of less than 15 inches and if the evaporation from a water surface exceeds 45 inches. Such areas, under irrigation, can be highly productive agriculturally and can also provide congenial living conditions. The extension of irrigation to new territories could contribute greatly to feeding and clothing the world's population.

The Influence on Summer Rainfall in the Lesotho Lowlands from Indian Ocean SSTs

2002 ◽  
Vol 33 (4) ◽  
pp. 305-318 ◽  
Author(s):  
Lars Hydén
Keyword(s):  
Indian Ocean ◽  
Southern Africa ◽  
Rainfall Variability ◽  
Austral Summer ◽  
Equatorial Indian Ocean ◽  
Summer Rainfall ◽  
Significant Negative Correlation ◽  
Annual Rainfall ◽  
Ocean Area ◽  
The Indian Ocean

Lesotho is located approximately at latitude 30 degrees south in the interior of Southern Africa. The mesoscale climate is complicated and governed by various weather systems. The inter-annual rainfall variability is great, resulting in low food security, since the growing of crops in the Lesotho Lowlands is almost exclusively rain-fed. Reliable forecasts of austral summer rainfall are thus valuable. Earlier research has shown that the sea surface temperatures (SST) in the Indian Ocean to some extent govern rainfall in Southern Africa. The research presented is part of an on-going project to find suitable oceanographic and meteorological predictors, which can be used in a forecast model for summer rainfall, to be developed later. The first part of this paper investigates the correlation between the average SSTs in the Equatorial Indian Ocean, the Central Indian Ocean, and the Agulhas Gyre, respectively, and rainfall two months later in the Lesotho Lowlands during early austral summer, October until December for the period 1949-1995. No significant correlations have been found, probably because the three ocean areas are too large. In the second part of this paper the monthly SST in 132 grid squares in the Indian Ocean were investigated and found to be correlated with rainfall in the Lesotho Lowlands two months later, October until March. Significant correlations have been found between the SSTs and certain ocean areas and December, January, and February rainfall, respectively. There is significant negative correlation between December rainfall and October SST in an ocean area between Kenya and Somalia across the Indian Ocean to Sumatra. In the area where the Somali Current flows there is also significant correlation between December SST and December rainfall. January rainfall is significantly negatively correlated with November SST in an ocean area, northeast of Madagascar. February rainfall is significantly, but weakly, negatively correlated with SST in a narrow north-south corridor in the Eastern Indian Ocean from the equator down to latitude 40 degrees south.

Tendencies in the geographical distribution of the genus Mariscus (Cyperaceae) in southern Africa*

Bothalia ◽  
1983 ◽  
Vol 14 (3/4) ◽  
Author(s):  
P. J. Voster
Keyword(s):  
Geographical Distribution ◽  
Southern Africa ◽  
Environmental Conditions ◽  
West Coast ◽  
Summer Rainfall ◽  
Annual Rainfall ◽  
The West ◽  
Water Requirements ◽  
Winter Rainfall ◽  
Flora Of Southern Africa

The genus Mariscus occurs over practically the whole of the Flora of Southern Africa (FSA) region, with the exception of the west coast and the Karoo region of the Cape Province. Practically no species occur under conditions of less than 250 mm of rain per annum, whereas the highest concentrations of subgenera/sections and species occur where the annual rainfall is more than 500 mm. All the species in the region are summer rainfall plants, or if they occur in the winter rainfall area they behave like summer rainfall plants. The different subgenera/sections recognized within the genus differ widely in respect of their water requirements, yet there is a general concentration of taxa in the eastern part of the country where the rainfall is higher than in the west. Nevertheless, the highest concentrations of taxa are not in the areas of highest rainfall, which suggests that topographical diversity is probably the most important factor determining concentrations of taxa. The geographical distribution of each subgenus/section in the FSA region is explained in relation to the total distribution of the subgenus/section. The possible climatic or environmental conditions which may determine the distribution of each subgenus/section are mentioned, and the concentration of species within each subgenus/section is demonstrated by means of maps.

U-Th dated late Pleistocene tufas linked to human occupation in the semi-arid southern Kalahari

2021 ◽  
Author(s):  
Jessica von der Meden ◽  
Jayne Wilkins ◽  
Benjamin Schoville ◽  
Kyle Brown ◽  
Robyn Pickering
Keyword(s):  
South Africa ◽  
Summer Rainfall ◽  
Middle Stone Age ◽  
Annual Rainfall ◽  
Human Populations ◽  
Stone Age ◽  
Human Occupation ◽  
Cape Coast ◽  
Climate Conditions ◽  
Semi Arid

<p>Ga-Mohana Hill North Rockshelter (GHN) in the Northern Cape Province of South Africa is situated within the Summer Rainfall Zone, in the semi-arid (~300-400mm mean annual rainfall) southeastern edge of the Kalahari Basin. This location is significant as the dominant narrative for the evolution of modern humans has focused on Middle Stone Age archaeological sites along the southern cape coast of South Africa, with coastal resources and favourable climate conditions argued as key factors in driving the evolution of <em>Homo sapiens</em>. Semi-arid regions in the interior of South Africa, such as the southern Kalahari Basin, are often considered to have been too dry to sustain significant human occupation and activity, and have thus been overlooked. However, GHN does indeed preserve rich stratified Middle and Later Stone Age deposits, as well as abundant large relict tufa deposits that cover the surrounding hillside. These tufas, which are ambient temperature, freshwater calcium carbonate deposits, are indicative of past periods of flowing surface waters and shallow pools on the hillside. Laser ablation trace element mapping was used to pre-screen the tufa samples to target layers with high <sup>238</sup>U and little to no <sup>232</sup>Th concentration for U-Th dating. The resultant ages show that the tufa system at Ga-Mohana was active during five distinct intervals over the last 110 ka, three of which closely coincide with the timing of human occupation at the site, itself dated via OSL. The coincidence of tufa formation and human occupation suggests that the tufa-forming waters were a critical resource to human populations living in the area. This hitherto undiscovered source of fresh water, more than 600 km inland and as far back as 110 ka, stands to challenge the notion of an empty and arid interior.</p>

scholarly journals Variation in Atmospheric Precipitation in Poland in the Years 2001–2018

Atmosphere ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 794 ◽  
Author(s):  
Agnieszka Ziernicka-Wojtaszek ◽  
Joanna Kopcińska
Keyword(s):  
Coefficient Of Variation ◽  
Urban Areas ◽  
Atmospheric Precipitation ◽  
Summer Rainfall ◽  
Annual Rainfall ◽  
Climate Change Scenarios ◽  
Temperature Changes ◽  
Surface Sealing ◽  
Observational Series ◽  
Annual Total

Climate change scenarios are in agreement as to the direction of air temperature changes in global warming, although the magnitude of the warming depends on the scenario adopted. In contrast, projections of changes in precipitation totals in Poland are not clear and obvious. Analysis of long-term observational series reveals no clear significant trends in levels of precipitation, despite periods of fluctuation, as well as an upward trend reported in the annual amount of precipitation, especially in northern Poland. However, the increasing variability of annual rainfall totals is commonly highlighted. In the years 1861–1990, the coefficient of variation of annual precipitation totals increased from about 10% to 16%. In the years 1971–2000, this coefficient for Poland increased to 17%, and in the period of 2001–2018, which is the subject of the present study, to 19%. Despite the lack of clear trends in annual totals, the increase in the coefficient of variation results in an increase in the frequency of both drought and floods. This unfavorable situation is exacerbated by the downward trend observed in the share of summer rainfall in the annual total. In urban areas with increasing surface sealing, the share of surface runoff in the water balance increases, and in this situation short-term rainfall will cause local flooding.

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