Drivers of Macrophyte and Diatom Diversity in a Shallow Hypertrophic Lake

We studied macrophyte and diatom assemblages and a range of environmental factors in the large hypertrophic Dehtář fishpond (Southern Bohemia, Czech Republic) over the course of several growing seasons. The spatial diversity of the environment was considered when collecting diatoms and water samples in three distinct parts of the fishpond, where automatic sensor stations continually measuring basic factors were established. Macrophytes were mapped in 30 segments of the fishpond littoral altogether. High species richness and spatiotemporal variability were found in assemblages of these groups of autotrophs. Water level fluctuations, caused by the interaction of fish farming management and climatic extremes, were identified as one of the most important factors shaping the structure and species composition of diatom and macrophyte assemblages. The distance of the sampling sites from large inflows reflected well the spatial variability within the fishpond, with important differences in duration of bottom drainage and exposure to disturbances in different parts of the fishpond. Disturbances caused by intensive wave action are most probably a crucial factor allowing the coexistence of species with different nutrient requirements under the hypertrophic conditions of the Dehtář fishpond. Due to a range of variables tested and climatic extremes encountered, our study may be considered as a basis for predictive model constructions in similar hypertrophic water bodies under a progressing climate change.

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Early Spring Snowmelt and Summer Droughts Strongly Impair the Resilience of Key Microbial Communities in Subalpine Grassland Ecosystems

10.1101/2021.03.15.435477 ◽

2021 ◽

Author(s):

Farhan Hafeez ◽

Lionel Bernard ◽

Jean-Christophe Clement ◽

Franck Poly ◽

Thomas Pommier

Keyword(s):

Microbial Communities ◽

Plant Biomass ◽

Early Spring ◽

Climatic Extremes ◽

Soil Microbial ◽

Cascading Effect ◽

Growing Seasons ◽

Grassland Ecosystems ◽

Microbial Responses ◽

Early Snowmelt

Subalpine grassland ecosystems are important from biodiversity, agriculture, and touristic perspectives but their resilience to seasonally occurring climatic extremes is increasingly challenged with climate change, accelerating their vulnerability to tipping points. Microbial communities, which are central in ecosystem functioning, are usually considered as more resistant and highly resilient to such extreme events due to their functional redundancy and strong selection in residing habitats. To investigate this, we explored the soil microbial responses upon recurrent summer droughts associated with early snowmelt in grasslands mesocosms set-up at the Lautaret Pass (French Alps). Potential respiration, nitrification and denitrification were monitored over a period of two growing seasons along with quantification of community gene abundances of total bacteria as well as (de)nitrifiers. Results revealed that droughts had a low and short-term impact on bacterial total respiration supporting their hypothesized high resistance and ability to recover. Nitrification and abundances of the corresponding functional guilds showed relatively strong resistance to summer droughts but declined in response to early snowmelt. This triggered a cascading effect on denitrification but also on the abundances of denitrifying communities which could recover from all climatic extremes except from the summer droughts where nitrifiers were collapsed. Denitrification and the respective functional groups faced high impact of applied stresses with strong reduction in the abundance and activity of this specialized community. Although, the consequently lower microbial competition for nitrate may be positive for plant biomass production, warnings exist when considering the potential nitrogen leaching from these ecosystems as well as risks of greenhouses gases emission such as N2O

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Exploring the environmental context of recent Didymosphenia geminata proliferation in Gaspésie, Quebec, using paleolimnology

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2013-0442 ◽

2014 ◽

Vol 71 (4) ◽

pp. 616-626 ◽

Cited By ~ 19

Author(s):

J.M. Lavery ◽

J. Kurek ◽

K.M. Rühland ◽

C.A. Gillis ◽

M.F.J. Pisaric ◽

...

Keyword(s):

Environmental Context ◽

Life Strategy ◽

Early 20Th Century ◽

Diatom Assemblages ◽

Eastern Canada ◽

Didymosphenia Geminata ◽

Planktonic Diatoms ◽

Growing Seasons ◽

Air Temperatures ◽

Scale Shift

Management authorities often perceive Didymosphenia geminata (didymo) as an invasive, nuisance diatom species that has been introduced to eastern Canada; however, observations from early 20th century diatom surveys challenge this characterization. We apply paleolimnological techniques to place recent didymo blooms from Gaspésie, Quebec, into historical and environmental context. Sedimentary diatom assemblages were examined from Lac Humqui (a headwater lake) and Lac au Saumon (a lake with an inflowing river currently supporting blooms). The Lac Humqui assemblage experienced a broad-scale shift in their dominant life strategy with declines in fragilarioid taxa and increases in planktonic diatoms (i.e., Cyclotella–Discostella species) that began ∼1970 and increased to modern abundances ∼1990. Strong relationships between this diatom shift and increases in regional air temperatures and earlier river ice-out dates are consistent with longer growing seasons and enhanced thermal stability in Lac Humqui. Didymo was observed throughout the Lac au Saumon core, demonstrating that it has been present in the region since at least ∼1970. Our paleolimnological evidence indicates that blooms likely form in response to regional consequences of climate warming, rather than human introduction.

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Eutrophication patterns in an eastern Mediterranean coastal lagoon: Vassova, Delta Nestos, Macedonia, Greece

Mediterranean Marine Science ◽

10.12681/mms.183 ◽

2005 ◽

Vol 6 (2) ◽

pp. 17 ◽

Cited By ~ 11

Author(s):

S. ORFANIDIS ◽

N. STAMATIS ◽

V. RAGIAS ◽

W. SCHRAMM

Keyword(s):

Coastal Lagoon ◽

Eastern Mediterranean ◽

Coastal Lagoons ◽

Fish Farming ◽

Basic Knowledge ◽

Spatiotemporal Variability ◽

Dissolved Phosphorus ◽

Salinity Gradients ◽

High Precipitation ◽

Water Values

The results of an intensive monitoring study of main eutrophication parameters in relation to fish farming management, climate and hydrography in the Vassova coastal lagoon (Nestos Delta) are presented. The overall aim is to produce basic knowledge in order to contribute to the management of eutrophication of coastal lagoons at local and national levels. Due to extensive spatiotemporal variability of the measured parameters correlation and regression polynomial analysis was used to identify patterns (p<0.05). Freshwater was the main source of nitrate and phosphate in the lagoon. This finding has justified the reduction of freshwater inflow in the past, which, however, has increased mean salinity to 30 PSU and reduced spatial salinity gradients. Maximum nitrate values in winter coincided with adverse climatic and hydrographic conditions (high precipitation, strong NE to E winds and low tide) and fish farming management that hinder water circulation. Dissolved phosphorus variability indicated the combination of the external (freshwaters) and internal (sediment) P-sources. N/P water values indicated nitrogen being the most important nutrient for primary producers throughout the year, except in winter, when phosphorus was the most important nutrient. Practical measures for improving fish farming practices to decrease “eutrophication risk” during winter are suggested. Existing nutrient data from the Vassova and from other Greek lagoons in comparison were also presented and discussed.

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Future hydrology and hydrological extremes under climate change in Asian river basins

Scientific Reports ◽

10.1038/s41598-021-96656-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Sangam Shrestha ◽

Deg-Hyo Bae ◽

Panha Hok ◽

Suwas Ghimire ◽

Yadu Pokhrel

Keyword(s):

Climate Change ◽

Southeast Asia ◽

River Flow ◽

Climate Change Impacts ◽

River Basins ◽

Global Scale ◽

Climatic Conditions ◽

Spatiotemporal Variability ◽

Climatic Extremes ◽

The Impact

AbstractThe diverse impacts of anthropogenic climate change in the spatiotemporal distribution of global freshwater are generally addressed through global scale studies, which suffer from uncertainties arising from coarse spatial resolution. Multi-catchment, regional studies provide fine-grained details of these impacts but remain less explored. Here, we present a comprehensive analysis of climate change impacts on the hydrology of 19 river basins from different geographical and climatic conditions in South and Southeast Asia. We find that these two regions will get warmer (1.5 to 7.8 °C) and wetter (− 3.4 to 46.2%) with the expected increment in river flow (− 18.5 to 109%) at the end of the twenty-first century under climate change. An increase in seasonal hydro-climatic extremes in South Asia and the rising intensity of hydro-climatic extremes during only one season in Southeast Asia illustrates high spatiotemporal variability in the impact of climate change and augments the importance of similar studies on a larger scale for broader understanding.

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FISH-RICE FARMING AREA AT MANIK RAMBUNG RICE FIELD SUPPORTED FOOD SECURITY IN NORTHERN SUMATRA````

Jurnal Pertanian Tropik ◽

10.32734/jpt.v2i2.2899 ◽

2015 ◽

Vol 2 (2) ◽

pp. 165-177

Author(s):

Ameilia Zuliyanti Siregar

Keyword(s):

Food Security ◽

Random Sampling ◽

Rice Field ◽

Aquatic Organisms ◽

Fish Farming ◽

Rice Cultivation ◽

Rice Farming ◽

Dominance Index ◽

Growing Seasons ◽

Produce Plant

Rice and fish have been an essential part of the life of Indonesian people which produce from rice field. The research was conducted during two years (Dec.2008 to Sept.2010) using a purposive random sampling using three plots in lowland and terrace from Manik Rambung Rice Field (MRRF). Two types of rice crops (Ciherang and IR 64) are cultivated showed 6 orders, 21 families, 34 taxa and 25 species. Oligochaeta, Ephemeroptera, Hemiptera, and Diptera were identified respective families, while families of Odonata and Coleoptera were further identified to species. There are three categories of Dominance Index (DI) in a rice field, these are D=Dominant ( 5% individual); A=Accessory (2.5%  D  5% individual) and O=Occasional (2.5% individual) with four families (Baetidae, Chironomidae, Tubificidae and Ceratopogonidae) as ranked high on the DI list. The Kruskal-Wallis test showed significant differences between the abundance of aquatic organisms during the time of sampling (χ2=1274.840, P=0.000), rice-growing seasons (χ2=16.393, P=0.001) and rice cultivation phases (χ2=8.618, df=4, P=0.004). The study about fish farming produce plant and animal proteins and sustainable for food security in Northern Sumatra.

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Spatiotemporal variability of E. coli concentrations in two irrigation ponds

10.5194/egusphere-egu21-6655 ◽

2021 ◽

Author(s):

Matthew Stocker ◽

Robert Hill ◽

Moon Kim ◽

Yakov Pachepsky

Keyword(s):

Spatial Patterns ◽

Spatiotemporal Variability ◽

Microbial Water Quality ◽

E Coli ◽

Growing Seasons ◽

The Mean ◽

Relative Differences ◽

Observation Times ◽

Observation Period

<p>Escherichia coli is the most commonly assessed indicator of fecal contamination. The presence of elevated levels of E. coli is used to evaluate the microbial water quality in recreational and irrigation water sources. &#160;E. coli concentrations are spatially and temporally variable. Monitoring of the variability inherent in water measurements can help create and implement effective monitoring designs and solutions. The objective of this work is to determine if there exist spatial patterns that are stable in time over years of observations. Two irrigation ponds in Maryland USA were monitored for three years during the growing seasons (June to August). Water samples and in situ measurements were collected in the same 47 locations biweekly for three years. The presence of stable spatial patterns was researched for relative differences between the logarithm of concentrations in specific locations and the average logarithm across the pond for each of observation times. The mean of these relative differences (MRD) over the observation period formed consistent spatial patterns. We found stable patterns of locations across the pond and found higher MRD values near the banks than the pond interiors. &#160;MRDs computed for separate years were more variable and had amplitudes different from the overall average MRD over the three years, although the similarities between patterns across years was apparent.&#160;</p>

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Indonesian coral reef habitats reveal exceptionally high species richness and biodiversity of diatom assemblages

Estuarine Coastal and Shelf Science ◽

10.1016/j.ecss.2021.107551 ◽

2021 ◽

pp. 107551

Author(s):

Yenny Risjani ◽

Andrzej Witkowski ◽

Adrian Kryk ◽

Yunianta ◽

Ewa Górecka ◽

...

Keyword(s):

Species Richness ◽

Coral Reef ◽

Diatom Assemblages ◽

High Species Richness

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Microrelief, Water Level Fluctuations, and Diameter Growth in Wet-site Stands of Red and Black Spruce in New Brunswick

Canadian Journal of Forest Research ◽

10.1139/x75-050 ◽

1975 ◽

Vol 5 (3) ◽

pp. 359-366 ◽

Cited By ~ 2

Author(s):

H. van Groenewoud

Keyword(s):

Water Table ◽

Black Spruce ◽

Maximum Growth ◽

Water Levels ◽

Water Level Fluctuations ◽

Diameter Growth ◽

Tree Diameter ◽

Growing Seasons ◽

Average Water ◽

The Mean

Soil water levels, rainfall, and tree diameter increments were measured during four successive growing seasons. Microrelief data and depth of the fluctuating water tables were incorporated into a measure of mean soil depth.Water table fluctuations were closely linked to rainfall. Deviations from the mean tree diameter growth were related to deviations from the mean depth of the water table. Maximum growth took place at the mean depth of the water table, with decreases in growth at higher or lower than average water levels.

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Diversity of water level fluctuations in degraded Baltic raised bogs

Ochrona Srodowiska i Zasobów Naturalnych ◽

10.1515/oszn-2017-0004 ◽

2017 ◽

Vol 28 (1) ◽

pp. 1-7

Author(s):

Filip Duda ◽

Ewa Woźniak ◽

Katarzyna Jereczek-Korzeniewska ◽

Roman Cieślińsk

Keyword(s):

Water Level ◽

Water Table ◽

Groundwater Level ◽

Atmospheric Precipitation ◽

Meteorological Conditions ◽

Precipitation Extreme ◽

Water Level Fluctuations ◽

Raised Bogs ◽

High Dynamic ◽

Different Parts

Abstract The aim of paper is to present the diversity of water level fluctuations in degraded Baltic raised bogs. An attempt was made to answer the question how strong the diversity of fluctuations is both within each object and between two objects situated close to each other. Moreover, speed and value of the response of water level to atmospheric precipitation were analysed. The spatial scope of the paper covers two Baltic raised bogs in the lower part of the Łeba river valley: Czarne Bagno and Łebskie Bagno. The time scope covers years 2012-2014. The study found that both analysed bogs were a high dynamic in variation of groundwater level. Annual amplitudes of fluctuations in the water table was in the range of 28.4 to 77.9 cm (Łebskie Bagno) and of 45.6 to 105.0 cm (Czarne Bagno). It has been observed that lowering the water level on both peatlands always been recorded in the summer months, whilst the increase in the autumn, which lasted until spring. Retention and the water level on peatlands influenced primarily precipitation. Extreme meteorological conditions that make it less conspicuous is the variation resulting from factors such as location in different parts of the bog or type of degradation.

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Historical medium-scale maps as a source of information on the overgrowing of lakes

Limnological Review ◽

10.2478/limre-2013-0017 ◽

2013 ◽

Vol 13 (3) ◽

pp. 155-162 ◽

Cited By ~ 4

Author(s):

Mariusz Ptak

Keyword(s):

Aerial Photographs ◽

Topographic Maps ◽

Water Level Fluctuations ◽

Individual Object ◽

Medium Scale ◽

Emergent Plants ◽

Main Lake ◽

Source Of Information ◽

Calculated Average ◽

Different Parts

AbstractIn the work, medium-scale topographic maps from the first half of the 20th century and aerial photographs from the first decade of the 21st century were used to determine the rate of overgrowing of lakes. A comparison of results for lakes located in different parts of Poland demonstrated that the process of proliferation of emergent plants dominated - such a situation was recorded for 14 out of the 15 lakes analysed in the work. The calculated average overgrowing rate for all the lakes in the years 1945-2010 was 0.4 ha yr-1. Lake Karaś (1.83 ha yr-1) and Lake Oświn (1.2 ha yr-1) were characterized by the highest overgrowing rates. Moreover, the work presents an attempt at discovering the factors which determine the scale of the lake overgrowing process. To this end, the main lake parameters were analysed and it was concluded that the rate of overgrowing of lakes was influenced, inter alia, by water level fluctuations and the shape and depth of a given lake. However, each lake should be treated as an individual object which responds to the processes occurring in its environment in a unique way.

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