Asynchronous responses of aquatic ecosystems to hydroclimatic forcing on the Tibetan Plateau

AbstractHigh-altitude ecosystems react sensitively to hydroclimatic triggers. Here we evaluated the ecological and hydrological changes in a glacier-influenced lake (Hala Hu, China) since the last glacial. Rapid fluctuations of aquatic biomarker concentrations, ratios, and hydrogen isotope values, from 15 to 14,000 and 8 to 5000 years before present, provided evidence for aquatic regime shifts and changes in lake hydrology. In contrast, most negative hydrogen isotope values of terrestrial biomarkers were observed between 9 and 7,000 years before present. This shows that shifts of vapour sources and increased precipitation amounts were not relevant drivers behind ecosystem changes in the studied lake. Instead, receding glaciers and increased meltwater discharge, driven by higher temperatures, caused the pronounced ecological responses. The shifts within phytoplankton communities in the Late Glacial and mid Holocene illustrate the vulnerability of comparable ecosystems to climatic and hydrological changes. This is relevant to assess future ecological responses to global warming.

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Hydrological Changes After the Last Ice Retreat in Northern Poland Using Radiocarbon Dating

Radiocarbon ◽

10.1017/s0033822200048633 ◽

2013 ◽

Vol 55 (3) ◽

pp. 1712-1723 ◽

Cited By ~ 8

Author(s):

Danuta J Michczyńska ◽

Leszek Starkel ◽

Dorota Nalepka ◽

Anna Pazdur

Keyword(s):

Radiocarbon Dating ◽

Late Glacial ◽

Simplified Model ◽

Peat Bogs ◽

Ice Melting ◽

Radiocarbon Dates ◽

Hydrological Changes ◽

Ice Retreat ◽

Late Glacial And Holocene ◽

The Last Glacial

A simplified model of hydrological changes during the Late Glacial and Holocene is presented for the northern Polish regions that were ice covered during the Last Glacial. This reconstruction is based on a group of 197 radiocarbon dates from about 120 localities reflecting the sequence of alternating lake transgressions and regressions. The earliest transgressions were related to dead-ice melting (sometimes in 2–3 phases), while the later ones started during more humid phases. However, these were usually followed by regressions, which may have been connected with the formation of new drainage systems and with the overgrowing of shallow lakes by peat bogs.

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Extracellular enzymatic activities in the aquatic ecosystems of the Danube Delta. 2. Alkaline phosphatase activity

ROMANIAN BIOTECHNOLOGICAL LETTERS ◽

10.25083/rbl/26.1/2269.2274 ◽

2021 ◽

Vol 26 (1) ◽

pp. 2269-2274

Author(s):

IOAN PĂCEŞILĂ ◽

EMILIA RADU

Keyword(s):

Alkaline Phosphatase ◽

Water Column ◽

Aquatic Ecosystems ◽

Temporal Dynamics ◽

Extracellular Enzyme ◽

Danube Delta ◽

Phytoplankton Communities ◽

Extracellular Enzymatic Activities ◽

Adjacent Channels ◽

Hydrolysis Of

Phosphorus is one of the most important inorganic nutrients in aquatic ecosystems, the development and functioning of the phytoplankton communities being often correlated with the degree of availability in assimilable forms of this element. Alkaline phosphatase (AP) is an extracellular enzyme with nonspecific activity that catalyses the hydrolysis of a large variety of organic phosphate esters and release orthophosphates. During 2011-2013, AP Activity (APA) was assessed in the water column and sediments of several aquatic ecosystems from Danube Delta: Roșu Lake, Mândra Lake and their adjacent channels – Roșu-Împuțita and Roșu-Puiu. The intensity of APA widely fluctuated, ranging between 230-2578 nmol p-nitrophenol L-1h-1 in the water column and 2104-15631 nmol p-nitrophenol g-1h-1 in sediment. Along the entire period of the study, APA was the most intense in Roșu-Împuțita channel, for both water and sediment samples. Temporal dynamics revealed its highest values in summer for the water column and in autumn for sediment. Statistical analysis showed significant seasonal diferences of the APA dynamics in spring vs. summer and autumn for the water column, and any relevant diferences for sediment.

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Agricultural Conservation Practices and Aquatic Ecological Responses

Water ◽

10.3390/w13121687 ◽

2021 ◽

Vol 13 (12) ◽

pp. 1687

Author(s):

Richard E. Lizotte ◽

Peter C. Smiley ◽

Robert B. Gillespie ◽

Scott S. Knight

Keyword(s):

Aquatic Ecosystems ◽

Harmful Algal Blooms ◽

Algal Blooms ◽

Soil Health ◽

Conservation Agriculture ◽

Agricultural Runoff ◽

The United States ◽

Ecosystem Structure ◽

Ecological Responses ◽

And Function

Conservation agriculture practices (CAs) have been internationally promoted and used for decades to enhance soil health and mitigate soil loss. An additional benefit of CAs has been mitigation of agricultural runoff impacts on aquatic ecosystems. Countries across the globe have agricultural agencies that provide programs for farmers to implement a variety of CAs. Increasingly there is a need to demonstrate that CAs can provide ecological improvements in aquatic ecosystems. Growing global concerns of lost habitat, biodiversity, and ecosystem services, increased eutrophication and associated harmful algal blooms are expected to intensify with increasing global populations and changing climate. We conducted a literature review identifying 88 studies linking CAs to aquatic ecological responses since 2000. Most studies were conducted in North America (78%), primarily the United States (73%), within the framework of the USDA Conservation Effects Assessment Project. Identified studies most frequently documented macroinvertebrate (31%), fish (28%), and algal (20%) responses to riparian (29%), wetland (18%), or combinations (32%) of CAs and/or responses to eutrophication (27%) and pesticide contamination (23%). Notable research gaps include better understanding of biogeochemistry with CAs, quantitative links between varying CAs and ecological responses, and linkages of CAs with aquatic ecosystem structure and function.

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Postglacial dispersal of freshwater fishes into Ontario

Canadian Journal of Zoology ◽

10.1139/z92-302 ◽

1992 ◽

Vol 70 (11) ◽

pp. 2247-2259 ◽

Cited By ~ 128

Author(s):

Nicholas E. Mandrak ◽

E. J. Crossman

Keyword(s):

North America ◽

Freshwater Fishes ◽

Eastern North America ◽

Glacial Period ◽

Before Present ◽

Last Glacial Period ◽

Historical Processes ◽

Dispersal Routes ◽

Atlantic Coastal ◽

The Last Glacial

The present-day distributions of 117 native freshwater fishes in Ontario have been shaped by processes active following the Wisconsinan glacial period, 80 000–10 000 years before present. During this glacial period, these species survived in unglaciated réfugia. To understand the processes that resulted in the recolonization of Ontario by fishes following the last glacial period, the refugial areas occupied by each species were determined using a refugial index, and glacial water bodies used as dispersal routes were identified. The refugial origins of the Ontario populations of 91 species were resolved. Seventy-two species resided in the Mississippian refugium, 13 species in the Atlantic Coastal refugium, 4 species in dual Atlantic Coastal – Mississippian refugia, 1 species in a Missourian refugium, and 1 species in Atlantic Coastal, Mississippian, and Missourian refugia. These conclusions differed significantly from those of other studies. Five general patterns were identified from the distributions of 104 species. In addition, there are 13 species that do not fit any of the general patterns. Most species with similar distributions in Ontario shared the same refugia and dispersal routes in eastern North America, therefore it is hypothesized that historical processes were important in shaping the present-day distributions of Ontario freshwater fishes.

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Summer aspect of phytoplankton communities in some Montenegrin lakes: Are there changes after more than two decades?

Archives of Biological Sciences ◽

10.2298/abs1202745r ◽

2012 ◽

Vol 64 (2) ◽

pp. 745-755

Author(s):

Jelena Rakocevic

Keyword(s):

Water Quality ◽

Sustainable Management ◽

Aquatic Ecosystems ◽

Phytoplankton Community ◽

Management Plan ◽

Phytoplankton Composition ◽

Qualitative And Quantitative ◽

Environmental Monitoring System ◽

Phytoplankton Communities ◽

Second Period

Qualitative and quantitative phytoplankton compositions of 10 Montenegrin lakes were investigated in the summer of 2007. The obtained results were compared with a previous study-period that was undertaken two decades ago. In the first period, diatoms numerically dominated the phytoplankton community in all studied lakes, while in the second period, the same was observed only in three of the ten lakes; in other studied lakes the relative contributions of green algae, dinoflagellates and/or cyanobacteria increased, while the contribution of diatoms decreased. The shift observed in phytoplankton composition and diversity in some of the studied lakes indicates an increase in the trophic level over the two decades. The sustainable management plan of the aquatic ecosystems in Montenegro should include the establishment of an environmental monitoring system in order to record any alterations that may take place in water quality.

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First report on phytoplankton communities of Barishal City, Bangladesh

Current Botany ◽

10.25081/cb.2020.v11.6296 ◽

2020 ◽

pp. 142-147

Author(s):

Shaswati Chakraborty ◽

Dipalok Karmaker ◽

Subroto Kumar Das ◽

Riyad Hossen

Keyword(s):

Aquatic Ecosystems ◽

Species Number ◽

Aquatic Environments ◽

Primary Producers ◽

First Report ◽

Biodiversity Indices ◽

Phytoplankton Communities ◽

Living Organisms ◽

The City ◽

Total Species

Phytoplanktons, also called microalgae, are microscopic photosynthetic living organisms that generally found in aquatic environments. Although they are considered as the most important primary producers and bioindicators of aquatic ecosystems, there was no previous report found for Barishal City about these tiny organisms. Consequently, the present study selected 10 freshwater reservoirs from the city to investigate phytoplankton communities and listed 110 taxa under 4 phyla, 7 classes, 18 orders, 24 families and 49 genera. The distribution of Chlorophytes was abundant relatively in terms of species number (45 taxa) followed by Euglenophytes, Chlorophytes and Cyanophytes in this area. Only Euglenaceae possessed one-third of the total species of this report. Among all stations, the highest number of taxa was recorded from station 2 and according to nine biodiversity indices, the station 2 and 9 showed comparatively good results. All of the recorded taxa were previously mentioned by different authors from Bangladesh.

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