scholarly journals Habitat selection by booming bitterns Botaurus stellaris in French Mediterranean reed-beds

Oryx ◽  
2005 ◽  
Vol 39 (3) ◽  
pp. 265-274 ◽  
Author(s):  
Brigitte Poulin ◽  
Gaëtan Lefebvre ◽  
Raphaël Mathevet
Keyword(s):  
Habitat Selection ◽  
Water Level ◽  
Environmental Changes ◽  
Open Water ◽  
Site Management ◽  
Clear Water ◽  
Percentage Cover ◽  
Multivariate Statistical ◽  
Reed Beds ◽  
Ecological Requirements

Data on habitat requirements of the threatened Eurasian bittern Botaurus stellaris are largely qualitative and limited to countries holding small populations. We assessed the habitat spectrum exploited by male bitterns during the breeding season, based on the analysis of 40 booming sites and 33 non-booming sites in 2,500 ha of heterogeneous reed-beds in the Camargue, France. Environmental variables contributing to booming site selection were, in decreasing order of importance, determined by their contribution to multivariate statistical models: water level in April, proportion of open water, density of dry and green reeds, percentage cover of non-reed species, salinity and turbidity of surface water, and reed height and diameter. Overall, booming sites were characterized by a homogeneous cover of relatively sparse green and dry reeds growing with other plant species in shallow (10–15 cm), clear water. Because these findings are contrary to the traditional perception of bittern habitat in Europe, a reassessment of the species' ecological requirements throughout its distributional range is warranted. In the Camargue the main factors involved in habitat selection (water level and dry reed density) are directly associated with site management, and bitterns respond rapidly to slight environmental changes.

scholarly journals A 7000-year history of coastal environmental changes from Mexico’s Pacific coast: A multi-proxy record from Laguna Mitla, Guerrero

The Holocene ◽  
2017 ◽  
Vol 27 (8) ◽  
pp. 1214-1226 ◽  
Author(s):  
Thomas A Bianchette ◽  
Terrence A McCloskey ◽  
Kam-biu Liu
Keyword(s):  
Water Level ◽  
Sea Level ◽  
Pacific Coast ◽  
Environmental Changes ◽  
Southern Oscillation ◽  
Open Water ◽  
Water Levels ◽  
Mangrove Swamp ◽  
Salt Pan ◽  
High Concentrations

The lack of multi-millennial multi-proxy paleoenvironmental reconstructions from Mexico’s Pacific coast has limited our understanding of the regional response to climate change and sea-level rise. A 479-cm core covering the last 6900 years was extracted from Laguna Mitla in the state of Guerrero on Mexico’s Pacific coast. Beginning as a Rhizophora-dominated salt pan ~6900 yr BP, at ~6500 yr BP, the site transitioned to a mangrove swamp dominated by Laguncularia, which lasted about 300 years. The beach barrier formed from ~6200 to 5200 yr BP, during which time, the site existed as an intermittently sheltered bay, the result of large, rapid changes in wave energy associated with the shifting barrier location and changes in stability. After the beach barrier was stabilized at ~5200 yr BP, water level at the coring site became a function of precipitation rather than sea level. Since that time, deposition has alternated between peat, laid down in a mangrove swamp, and clay intervals characterized by high concentrations of titanium and a predominantly regional pollen signal, representing open-water lagoon phases. Seven periods of increased water level, varying in duration, occurred during the backbarrier period, with El Niño-Southern Oscillation (ENSO) likely the main climatic mechanism causing these periodic shifts in the paleo-precipitation levels. We suggest that the deepest water levels detected over the last ~3200 years correlate with periods of increased ENSO activity. The spatial distribution of tropical cyclone rainfall, which represents a significant percentage of total annual precipitation along Mexico’s Pacific coast, may explain the inconsistencies between our record and paleoclimatic records from Mexico’s interior, but more work is needed to test this hypothesis.

scholarly journals N2O dynamics in the western Arctic Ocean during the summer of 2017

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jang-Mu Heo ◽  
Seong-Su Kim ◽  
Sung-Ho Kang ◽  
Eun Jin Yang ◽  
Ki-Tae Park ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Environmental Changes ◽  
Chukchi Sea ◽  
Hot Spot ◽  
Open Water ◽  
Northern Region ◽  
The Arctic ◽  
Western Arctic Ocean ◽  
Deep Layers ◽  
Western Arctic

AbstractThe western Arctic Ocean (WAO) has experienced increased heat transport into the region, sea-ice reduction, and changes to the WAO nitrous oxide (N2O) cycles from greenhouse gases. We investigated WAO N2O dynamics through an intensive and precise N2O survey during the open-water season of summer 2017. The effects of physical processes (i.e., solubility and advection) were dominant in both the surface (0–50 m) and deep layers (200–2200 m) of the northern Chukchi Sea with an under-saturation of N2O. By contrast, both the surface layer (0–50 m) of the southern Chukchi Sea and the intermediate (50–200 m) layer of the northern Chukchi Sea were significantly influenced by biogeochemically derived N2O production (i.e., through nitrification), with N2O over-saturation. During summer 2017, the southern region acted as a source of atmospheric N2O (mean: + 2.3 ± 2.7 μmol N2O m−2 day−1), whereas the northern region acted as a sink (mean − 1.3 ± 1.5 μmol N2O m−2 day−1). If Arctic environmental changes continue to accelerate and consequently drive the productivity of the Arctic Ocean, the WAO may become a N2O “hot spot”, and therefore, a key region requiring continued observations to both understand N2O dynamics and possibly predict their future changes.

Lake and inland dunes as interconnected Systems: The story of Lake Tresssee and an adjacent dune field (Schleswig-Holstein, North Germany)

The Holocene ◽  
2020 ◽  
pp. 095968362098168
Author(s):  
Christian Stolz ◽  
Magdalena Suchora ◽  
Irena A Pidek ◽  
Alexander Fülling
Keyword(s):  
Water Level ◽  
Bronze Age ◽  
Environmental Changes ◽  
High Water ◽  
Alluvial Fan ◽  
Water Levels ◽  
Lake Area ◽  
Dune Field ◽  
The North ◽  
Sand Drift

The specific aim of the study was to investigate how four adjacent geomorphological systems – a lake, a dune field, a small alluvial fan and a slope system – responded to the same impacts. Lake Tresssee is a shallow lake in the North of Germany (Schleswig-Holstein). During the Holocene, the lake’s water surface declined drastically, predominately as a consequence of human impact. The adjacent inland dune field shows several traces of former sand drift events. Using 30 new radiocarbon ages and the results of 16 OSL samples, this study aims to create a new timeline tracing the interaction between lake and dunes, as well, as how both the lake and the dunes reacted to environmental changes. The water level of the lake is presumed to have peaked during the period before the Younger Dryas (YD; start at 10.73 ka BC). After the Boreal period (OSL age 8050 ± 690 BC) the level must have undergone fluctuations triggered by climatic events and the first human influences. The last demonstrable high water level was during the Late Bronze Age (1003–844 cal. BC). The first to the 9th century AD saw slightly shrinking water levels, and more significant ones thereafter. In the 19th century, the lake area was artificially reduced to a minimum by the human population. In the dunes, a total of seven different phases of sand drift were demonstrated for the last 13,000 years. It is one of the most precisely dated inland-dune chronologies of Central Europe. The small alluvial fan took shape mainly between the 13th and 17th centuries AD. After 1700 cal. BC (Middle Bronze Age), and again during the sixth and seventh centuries AD, we find enhanced slope activity with the formation of Holocene colluvia.

scholarly journals Responses of Benthic Macroinvertebrate Communities of Two Tropical, High-Mountain Lakes to Climate Change and Deacidification

Diversity ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 243
Author(s):  
Javier Alcocer ◽  
Luis A. Oseguera ◽  
Diana Ibarra-Morales ◽  
Elva Escobar ◽  
Lucero García-Cid
Keyword(s):  
Climate Change ◽  
Species Richness ◽  
Water Temperature ◽  
Water Level ◽  
Environmental Changes ◽  
Mountain Lakes ◽  
High Mountain ◽  
Macroinvertebrate Communities ◽  
High Mountain Lakes ◽  
La Luna

High-mountain lakes are among the most comparable ecosystems globally and recognized sentinels of global change. The present study pursued to identify how the benthic macroinvertebrates (BMI) communities of two tropical, high mountain lakes, El Sol and La Luna, Central Mexico, have been affected by global/regional environmental pressures. We compared the environmental characteristics and the BMI communities between 2000–2001 and 2017–2018. We identified three principal environmental changes (the air and water temperature increased, the lakes’ water level declined, and the pH augmented and became more variable), and four principal ecological changes in the BMI communities [a species richness reduction (7 to 4), a composition change, and a dominant species replacement all of them in Lake El Sol, a species richness increase (2 to 4) in Lake La Luna, and a drastic reduction in density (38% and 90%) and biomass (92%) in both lakes]. The air and water temperature increased 0.5 °C, and lakes water level declined 1.5 m, all suggesting an outcome of climate change. Contrarily to the expected acidification associated with acid precipitation, both lakes deacidified, and the annual pH fluctuation augmented. The causes of the deacidification and the deleterious impacts on the BMI communities remained to be identified.

scholarly journals Sea-ice edge is more important than closer open water access for foraging Adélie penguins: evidence from two colonies

2020 ◽  
Vol 640 ◽  
pp. 215-230
Author(s):  
C Michelot ◽  
A Kato ◽  
T Raclot ◽  
K Shiomi ◽  
P Goulet ◽  
...  
Keyword(s):  
Sea Ice ◽  
Environmental Changes ◽  
Early Stage ◽  
Open Water ◽  
Gps Tracking ◽  
Ice Edge ◽  
Sea Ice Edge ◽  
Study Sites ◽  
The Impact ◽  
Adélie Penguins

Sentinel species, like Adélie penguins, have been used to assess the impact of environmental changes, and their link with sea ice has received considerable attention. Here, we tested if foraging Adélie penguins from 2 colonies in East Antarctica target the distant sea-ice edge or take advantage of closer open waters that are readily available near their colony. We examined the foraging behaviour of penguins during the incubation trips of females in 2016 and males in 2017, using GPS tracking and diet data in view of daily sea-ice data and bathymetry. In 2016-2017, sea-ice cover was extensive during females’ trips but flaw leads and polynyas were close to both study sites. Sea ice receded rapidly during males’ trips in 2017-2018. Despite close open water near both colonies in both years, females and males preferentially targeted the continental slope and the sea-ice edge to forage. In addition, there was no difference in the diet of penguins from both colonies: all penguins fed mostly on Antarctic krill and males also foraged on Antarctic silverfish. Our results highlight the importance of the sea-ice edge for penguins, an area where food abundance is predictable. It is likely that resource availability was not sufficient in closer open water areas at such an early stage in the breeding season. The behaviours displayed by the penguins from both colonies were similar, suggesting a common behaviour across colonies in Terre Adélie, although additional sites would be necessary to confirm this hypothesis.

scholarly journals Regulation of Vegetation and Evapotranspiration by Water Level Fluctuation in Shallow Lakes

Water ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 2651
Author(s):  
Qiang Liu ◽  
Liqiao Liang ◽  
Xiaomin Yuan ◽  
Sirui Yan ◽  
Miao Li ◽  
...  
Keyword(s):  
Water Level ◽  
Open Water ◽  
Water Area ◽  
Water Level Fluctuation ◽  
Water Levels ◽  
Water Level Fluctuations ◽  
Water Evaporation ◽  
Level Fluctuation ◽  
Open Water Area ◽  
Annual Scale

Water level fluctuations play a critical role in regulating vegetation distribution, composition, cover and richness, which ultimately affect evapotranspiration. In this study, we first explore water level fluctuations and associated impacts on vegetation, after which we assess evapotranspiration (ET) under different water levels. The normalized difference vegetation index (NDVI) was used to estimate the fractional vegetation cover (Fv), while topography- and vegetation-based surface-energy partitioning algorithms (TVET model) and potential evaporation (Ev) were used to calculate ET and water evaporation (Ep). Results show that: (1) water levels were dramatically affected by the combined effect of ecological water transfer and climate change and exhibited significant decreasing trends with a slope of −0.011 m a−2; and (2) as predicted, there was a correlation between water level fluctuation at an annual scale with Phragmites australis (P. australis) cover and open-water area. Water levels also had a controlling effect on Fv values, an increase in annual water levels first increasing and then decreasing Fv. However, a negative correlation was found between Fv values and water levels during initial plant growth stages. (iii) ET, which varied under different water levels at an annual scale, showed different partition into transpiration from P. australis and evaporation from open-water area and soil with alterations between vegetation and open water. All findings indicated that water level fluctuations controlled biological and ecological processes, and their structural and functional characteristics. This study consequently recommends that specifically-focused ecological water regulations (e.g., duration, timing, frequency) should be enacted to maintain the integrity of wetland ecosystems for wetland restoration.

scholarly journals The ratio of methanogens to methanotrophs and water-level dynamics drive methane transfer velocity in a temperate kettle-hole peat bog

2019 ◽  
Vol 16 (16) ◽  
pp. 3207-3231 ◽  
Author(s):  
Camilo Rey-Sanchez ◽  
Gil Bohrer ◽  
Julie Slater ◽  
Yueh-Fen Li ◽  
Roger Grau-Andrés ◽  
...  
Keyword(s):  
Water Level ◽  
Pore Water ◽  
Relative Abundance ◽  
Water Concentration ◽  
Open Water ◽  
Peat Bog ◽  
Transfer Velocity ◽  
Ch4 Flux ◽  
Kettle Hole ◽  
Vegetation Zones

Abstract. Peatlands are a large source of methane (CH4) to the atmosphere, yet the uncertainty around the estimates of CH4 flux from peatlands is large. To better understand the spatial heterogeneity in temperate peatland CH4 emissions and their response to physical and biological drivers, we studied CH4 dynamics throughout the growing seasons of 2017 and 2018 in Flatiron Lake Bog, a kettle-hole peat bog in Ohio. The site is composed of six different hydro-biological zones: an open water zone, four concentric vegetation zones surrounding the open water, and a restored zone connected to the main bog by a narrow channel. At each of these locations, we monitored water level (WL), CH4 pore-water concentration at different peat depths, CH4 fluxes from the ground and from representative plant species using chambers, and microbial community composition with a focus here on known methanogens and methanotrophs. Integrated CH4 emissions for the growing season were estimated as 315.4±166 mgCH4m-2d-1 in 2017 and 362.3±687 mgCH4m-2d-1 in 2018. Median CH4 emission was highest in the open water, then it decreased and became more variable through the concentric vegetation zones as the WL dropped, with extreme emission hotspots observed in the tamarack mixed woodlands (Tamarack) and low emissions in the restored zone (18.8–30.3 mgCH4m-2d-1). Generally, CH4 flux from above-ground vegetation was negligible compared to ground flux (<0.4 %), although blueberry plants were a small CH4 sink. Pore-water CH4 concentrations varied significantly among zones, with the highest values in the Tamarack zone, close to saturation, and the lowest values in the restored zone. While the CH4 fluxes and pore-water concentrations were not correlated with methanogen relative abundance, the ratio of methanogens to methanotrophs in the upper portion of the peat was significantly correlated to CH4 transfer velocity (the CH4 flux divided by the difference in CH4 pore-water concentration between the top of the peat profile and the concentration in equilibrium with the atmosphere). Since ebullition and plant-mediated transport were not important sources of CH4 and the peat structure and porosity were similar across the different zones in the bog, we conclude that the differences in CH4 transfer velocities, and thus the flux, are driven by the ratio of methanogen to methanotroph relative abundance close to the surface. This study illustrates the importance of the interactions between water-level and microbial composition to better understand CH4 fluxes from bogs and wetlands in general.

Emergent plant communities of oxbow lakes in northeastern Alberta: salinity, water-level fluctuation, and succession

1984 ◽  
Vol 62 (2) ◽  
pp. 310-316 ◽  
Author(s):  
V. J. Lieffers
Keyword(s):  
Water Level ◽  
Detrended Correspondence Analysis ◽  
Open Water ◽  
Water Levels ◽  
Water Level Fluctuations ◽  
Individual Species ◽  
Acorus Calamus ◽  
Oxbow Lakes ◽  
Salinity Water ◽  
Northeastern Alberta

Emergent vegetation was sampled in 15 oxbow lakes in a 50-km segment of the Athabasca River in northeastern Alberta. Cover of individual species was visually assessed in plots at the outer, middle, and (or) inner edge of the emergent zone of each lake (n, 37 sample units). Detrended correspondence analysis showed two main axes of variation. The first axis related to salinity. Water conductivity ranged from 170 to 12200 μS cm−1 and community types ranged from freshwater fens to saline wetland communities dominated by Scolochloa festucacea, Scirpus maritimus, and Triglochin maritima. The second axis of variation related to water-level fluctuations. Half of the lakes had an increase in water level in the recent past (ca. 6–30 years). In these lakes, Typha latifolia was dominant in both grounded and floating substrates subjected to increased water levels. Sedge communities dominated by Carex rostrata, C. aquatilis, and Acorus calamus were common in sites with stable water levels. In freshwater lakes, floating substrates were established over open water by the lateral growth of floating stems of Calla palustris and Potentilla palustris. Floating substrates were not in the saline sites probably because these open-water colonizers were not present under saline regimes.

The effects of water-level changes on periphytic algal assemblages in Poyang Lake

2020 ◽  
Author(s):  
Kuimei Qian ◽  
Martin Dokulil ◽  
Wan Lei ◽  
Yuwei Chen
Keyword(s):  
Water Level ◽  
Algal Biomass ◽  
Environmental Changes ◽  
Poyang Lake ◽  
Temporal Variations ◽  
Algal Community ◽  
Temperature Conductivity ◽  
Periphytic Algae ◽  
Water Level Changes ◽  
Algal Assemblages

Poyang Lake, which is the largest freshwater lake in China, has a seasonal flooding cycle that significantlychanges the water level every year. The aim of this study was to research the effects of water-level changeson periphytic algal assemblages in Poyang Lake. Dynamic shift of periphytic algal biomass were studied fromNovember 2016 to July 2019. Periphytic algal biomass and species composition were analyzed microscopically, andphysicochemical conditions were measured. There were significant seasonal variations in the community distributionof periphytic algae. The biomass of the periphyton ranged from 8 to 22,636 mg m-2. Periphytic algal biomassranged from 30 to 622 mg m-2 with the average of 204 mg m-2 in the LWL phase; periphytic algal biomass rangedfrom 8 to 21,839 mg m-2, with the average of 3,399 mg m-2 in the IWL phase. It ranged from 166 to 22,636 mgm-2, with the average 4,320 mg m-2 in the HWL phase and from 16 to 3,231 mg m-2 with the average of 585 mgm-2 in the DWL phase. There were temporal variations in periphytic algal community structure in Poyang Lake.Cryptophyceae dominated in algal periphyton from November 2016 to February 2017. Bacillariophyceae dominatedfrom March to July 2017 (increasing water-level phases). Pyrrophyceae and Euglenophyceae were dominant fromAugust and September (high-water-level phase) in 2017. Bacillariophyceae dominated through 2018 with occasionaldominance of Cryptophyceae from January to June and the occasional dominance of Chlorophyceae fromJuly to December. Chlorophyceae dominated from January to July in 2019 with occasional dominance of Bacillariophyceae.The water-level variations led to environmental heterogeneity in Poyang Lake, creating heterogeneoushabitats for algal periphyton. Our study revealed the primary importance of water level, water temperature, conductivity,total nitrogen, nitrite and total phosphorus as abiotic local factors structuring the periphytic algal communityin Poyang Lake. The water-level changes did not prevent growth of periphytic algae, but it did change the periphyticalgal community assemblages. This research provides data on the periphytic algae in Poyang Lake and will beuseful for establishing biological indicators of environmental changes and protecting Poyang Lake in the future.

scholarly journals Phytoplankton response to fish-induced environmental changes in a temperate shallow pond-type lake

2017 ◽  
Vol 25 (4) ◽  
pp. 211-262 ◽  
Author(s):  
Agnieszka Napiórkowska-Krzebietke
Keyword(s):  
Phytoplankton Biomass ◽  
Environmental Changes ◽  
Silver Carp ◽  
Ecological Status ◽  
Ctenopharyngodon Idella ◽  
Predatory Fish ◽  
Turbid Water ◽  
Clear Water ◽  
Water State ◽  
Pond Type

AbstractSince 1967, the temperate, shallow, pond-type Lake Warniak has been subjected to different biomanipulation methods including the introduction of common carp,Cyprinus carpioL., grass carp,Ctenopharyngodon idella(Val.), silver carp,Hypophthalmichthys molitrix(Val.), and bighead carp,Hypophthalmichthys nobilis(Richardson) and then their removal in an effort to control macrophytes and phytoplankton. Recently, pilot stocking with predatory fish, particularly pike,Esox luciusL., has also been conducted. Hence, an examination of the long-term response patterns of phytoplankton to multiple fish-induced stressors was undertaken. In recent years,Charadomination (2000-2004) has helped to stabilize a clear-water state, high/good ecological status, and meso-eutrophic conditions. After the disappearance of Charales in 2004, the rapid, unstable changes in phytoplankton biomass, structure, and biodiversity suggested a shift toward a turbid-water state. As a result, the phytoplankton assemblages changed from those dominated by cryptophytes Y+X2+X1+LO(2000-2004) through those dominated by cyanobacteria K (2005-2008), dinoflagellates LO+Y (2009-2011), and cryptophytes Y+LO+F+X2 (2012), to those dominated by diatoms D+K+P+A (2013-2014) with representative taxa that occur in nutrient-rich and/or nutrient-poor water bodies. The 1967-2014 changes indicated that four periods, two with clear-water state and two with turbid-water state, alternately, one after the other, resulted from different fish pressure. Higher autochthonous fish biomass was usually accompanied by lower phytoplankton biomass. In contrast, the introduction of Cyprinidae fish had a stimulating effect on summer phytoplankton dominated by cyanobateria. Among the nutrients, only phosphorus played an important role.

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