scholarly journals Lethal microbial blooms delayed freshwater ecosystem recovery following the end-Permian extinction

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Chris Mays ◽  
Stephen McLoughlin ◽  
Tracy D. Frank ◽  
Christopher R. Fielding ◽  
Sam M. Slater ◽  
...  

AbstractHarmful algal and bacterial blooms linked to deforestation, soil loss and global warming are increasingly frequent in lakes and rivers. We demonstrate that climate changes and deforestation can drive recurrent microbial blooms, inhibiting the recovery of freshwater ecosystems for hundreds of millennia. From the stratigraphic successions of the Sydney Basin, Australia, our fossil, sedimentary and geochemical data reveal bloom events following forest ecosystem collapse during the most severe mass extinction in Earth’s history, the end-Permian event (EPE; c. 252.2 Ma). Microbial communities proliferated in lowland fresh and brackish waterbodies, with algal concentrations typical of modern blooms. These initiated before any trace of post-extinction recovery vegetation but recurred episodically for >100 kyrs. During the following 3 Myrs, algae and bacteria thrived within short-lived, poorly-oxygenated, and likely toxic lakes and rivers. Comparisons to global deep-time records indicate that microbial blooms are persistent freshwater ecological stressors during warming-driven extinction events.

2013 ◽  
Vol 25 (1-2) ◽  
pp. 136-148
Author(s):  
I. V. Gryb

The concept of an explosion in freshwater ecosystems as a result of the release of accumulated energy, accompanied by the destruction of the steady climax successions of hydrocenoses is presented. The typification of local explosions as well as methods for assessing their risk during the development of river basins are shown. The change in atmospheric circulation, impaired phases of the hydrological regime of rivers, increasing the average temperature of the planet, including in Polesie to 0,6 ºC, deforestation leads to concentration and release of huge amounts of unmanaged terrestrial energy, which manifests itself in the form of disasters and emergencies. Hydroecological explosion is formed as a result of multifactorial external influence (natural and anthropogenic) on the water body in a certain period of time. Moreover, its level at wastewater discharge depends on the mass of recycled impurities and behaved processing capacity of the reservoir, and the mass of dumped on biocides and the possibility of the water flow to their dilution and to the utilization of non-toxic concentrations. In all these cases the preservation of "centers of life" in the tributaries of the first order – local fish reproduction areas contributed to ecosystem recovery, and the entire ecosystem has evolved from equilibrium to non-equilibrium with further restructuring after the explosion and environmental transition to a new trophic level. It means that hydroecological explosion can be researched as the logical course of development of living matter in abiotic environmental conditions, ending abruptly with the formation of new species composition cenoses and new bio-productivity. The buffer capacity of the water environment is reduced due to re-development and anthropic transformation of geobiocenoses of river basins, which leads to a weakening of life resistance. This applies particularly to the southern industrial regions of Ukraine, located in the arid zone that is even more relevant in the context of increased average temperature due to the greenhouse effect, as well as to Polesie (Western, Central and Chernihiv), had been exposed to large-scale drainage of 60-80th years, which contributed to the degradation of peatlands and fitostroma. Imposing the western trace of emissions from the Chernobyl accident to these areas had created the conditions of prolonged hydroecological explosion in an intense process of aging water bodies, especially lakes, change in species composition of fish fauna and the occurrence of neoplasms at the organismal level. Under these conditions, for the existence of man and the environment the vitaukta should be strengthened, i.e. buffer resistance and capacitance the aquatic environment, bioefficiency on the one hand and balanced using the energy deposited - on the other. This will restore the functioning of ecosystems "channel-floodplain", "riverbed-lake", reducing the energy load on the aquatic environment. Hydroecological explosions of natural origin can not be considered a pathology – it is a jump process of natural selection of species of biota. Another thing, if they are of anthropogenic origin and if the magnitude of such an impact is on the power of geological factors. Hydroecological explosions can be regarded as a manifestation of environmental wars that consciously or unconsciously, human society is waging against themselves and their kind in the river basins, so prevention of entropy increase in the aquatic environment and the prevention of hydroecological explosions is a matter of human survival. While the man - is not the final link in the development of living matter, it can develop without him, as matter is eternal, and the forms of its existence are different.


2019 ◽  
pp. 227-232
Author(s):  
Edward B. Barbier

This concluding chapter looks at the future of water. There are two possible paths for managing water. First, if the world continues with inadequate governance and institutions, incorrect market signals, and insufficient innovations to improve efficiency and manage competing demands, most chronic water and scarcity problems will continue to worsen. The world will see a future of declining water security, freshwater ecosystem degradation, and increasing disputes and conflicts over remaining water resources. The alternative path to managing water is the one offered by this book. If, in anticipation of the coming decades of increasing water scarcity, humankind is able to develop appropriate governance and institutions for water management, instigate market and policy reforms, and address global management issues, then improved innovation and investments in new water technologies and better protection of freshwater ecosystems should secure sufficient beneficial water use for a growing world population.


Author(s):  
Matthew McCartney

Freshwater ecosystems are naturally dynamic. The source of water, discharge, turnover, and residence times all affect which organisms can live in different freshwater habitats and are key determinants of freshwater ecosystem structure and function. Human-induced changes to the volume and timing of both surface and ground water flows are a leading driver of global declines in freshwater biodiversity and are likely to be exacerbated by climate change. The conservation of many wetlands around the world, including in some cases the preservation of unique flora and fauna, is now entirely dependent on continued human intervention and water management. Such management can only be successful if based on sound understanding of water budgets and hydrological processes informed by accurate hydrological monitoring. This chapter provides a brief introduction to hydrological monitoring—what needs to be measured and how—for freshwater ecology and conservation.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Claudia Santori ◽  
Ricky-John Spencer ◽  
Michael B. Thompson ◽  
Camilla M. Whittington ◽  
Thomas H. Burd ◽  
...  

Abstract Humans are increasing the frequency of fish kills by degrading freshwater ecosystems. Simultaneously, scavengers like freshwater turtles are declining globally, including in the Australian Murray–Darling Basin. Reduced scavenging may cause water quality problems impacting both ecosystems and humans. We used field and mesocosm experiments to test whether scavenging by turtles regulates water quality during simulated fish kills. In the field, we found that turtles were important scavengers of fish carrion. In mesocosms, turtles rapidly consumed carrion, and water quality in mesocosms with turtles returned to pre-fish kill levels faster than in turtle-free controls. Our experiments have important ecological implications, as they suggest that turtles are critical scavengers that regulate water quality in freshwater ecosystems. Recovery of turtle populations may be necessary to avoid the worsening of ecosystem health, particularly after fish kills, which would have devastating consequences for many freshwater species.


2020 ◽  
Vol 10 (4) ◽  
pp. 20190140 ◽  
Author(s):  
Noah J. Planavsky ◽  
Leslie J. Robbins ◽  
Balz S. Kamber ◽  
Ronny Schoenberg

Deciphering the role—if any—that free oxygen levels played in controlling the timing and tempo of the radiation of complex life is one of the most fundamental questions in Earth and life sciences. Accurately reconstructing Earth's redox history is an essential part of tackling this question. Over the past few decades, there has been a proliferation of research employing geochemical redox proxies in an effort to tell the story of Earth's oxygenation. However, many of these studies, even those considering the same geochemical proxy systems, have led to conflicting interpretations of the timing and intensity of oxygenation events. There are two potential explanations for conflicting redox reconstructions: (i) that free oxygen levels were incredibly dynamic in both time and space or (ii) that collectively, as a community—including the authors of this article—we have frequently studied rocks affected by secondary weathering and alteration (particularly secondary oxidation) while neglecting to address the impact of this alteration on the generated data. There are now multiple case studies that have documented previously overlooked secondary alteration, resolving some of the conflicting constrains regarding redox evolution. Here, an analysis of a large shale geochemistry database reveals significant differences in cerium (Ce) anomalies, a common palaeoredox proxy, between outcrop and drill core samples. This inconsistency provides support for the idea that geochemical data from altered samples are frequently published in the peer-reviewed literature. As individuals and a geochemical community, most of us have been slow to appreciate how pervasive the problem is but there are examples of other communities that have faced and met the challenges raised by such quality control crises. Further evidence of the high potential for alteration of deep-time geochemical samples, and recognition of the manner in which this may lead to spurious results and palaeoenvironmental interpretations, indicate that sample archiving, in publicly accessible collections needs to become a prerequisite for publication of new palaeoredox data. Finally, the geochemical community need to think about ways to implement additional quality control measures to increase the fidelity of palaeoredox proxy work.


The Holocene ◽  
2012 ◽  
Vol 22 (12) ◽  
pp. 1451-1460 ◽  
Author(s):  
Joshua R Thienpont ◽  
Daniel Johnson ◽  
Holly Nesbitt ◽  
Steven V Kokelj ◽  
Michael FJ Pisaric ◽  
...  

Because of decreasing sea-ice extent and increasingly frequent Arctic storms, low-lying coastal ecosystems are at heightened risk from marine storm surges. A major Arctic storm event originating in the Beaufort Sea in September 1999 resulted in the flooding of a large area of the outer alluvial plain of the Mackenzie Delta (Northwest Territories, Canada), and has been previously shown to have caused unprecedented impacts on the terrestrial ecosystems on a regional scale. We use diatoms preserved in lake sediment cores to gain a landscape perspective on the impact of the storm on freshwater systems, and to determine if other such events have occurred in the recent past. Our results indicate that five lakes located at the coastal edge of the low-lying Mackenzie Delta show strong, synchronous, and previously unobserved increases in the relative abundance of brackish-water diatom taxa coincident with the timing of the 1999 storm surge. These changes were not observed at a control site located farther inland. The degree to which the storm surge impacted the chemical and biological limnology of the lakes varied, and was not explained by measured physical variables, suggesting the degree of impact is likely related to a combination of factors including distance from the coast, the size:volume ratio of the lake and its catchment, and water residence time. We show that the 1999 storm surge resulted in unmatched broadscale impacts on the freshwater ecosystems of the outer Mackenzie Delta, and that while minimal recovery may be occurring in some of the systems, the lakes studied remain chemically and biologically impacted more than a decade after the inundation event.


2019 ◽  
Vol 10 (2) ◽  
pp. 1562-1565
Author(s):  
Ebtesam Kadem Khudher ◽  
Ahmed Sabah AL-Jasimee

Bio-indicators such as diatoms from algae considered to be key factors in ecological studies as an assessment of freshwater ecology. Algae are very sensitive to environmental changes and reflect the spatiotemporal changes on exists or biomass of diatoms in waters. Diatoms have been used not just for the assessment of water quality, but also can be used as an organic pollution indicator in the freshwater ecosystems, such as algal water bloom. The reason for using diatoms as bio-indicators was for several characteristics such as rapid growth, and represent high biomass in the freshwater ecosystem. Also, diatoms have high biodiversity among the other aquatic biota and energy flow and cycling. Compared with the other aquatic biota, diatoms reflect ecological disturbance due to high sensitivity to light, temperature, water flow, pH, and oxygen content. Additionally, diatoms are used as an assessment of eutrophication, organic pollution and climate change.


PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0238013
Author(s):  
Takehiro Kazama ◽  
Kazuhide Hayakawa ◽  
Victor S. Kuwahara ◽  
Koichi Shimotori ◽  
Akio Imai ◽  
...  

Direct measurements of gross primary productivity (GPP) in the water column are essential, but can be spatially and temporally restrictive. Fast repetition rate fluorometry (FRRf) is a bio-optical technique based on chlorophyll a (Chl-a) fluorescence that can estimate the electron transport rate (ETRPSII) at photosystem II (PSII) of phytoplankton in real time. However, the derivation of phytoplankton GPP in carbon units from ETRPSII remains challenging because the electron requirement for carbon fixation (Фe,C), which is mechanistically 4 mol e− mol C−1 or above, can vary depending on multiple factors. In addition, FRRf studies are limited in freshwater lakes where phosphorus limitation and cyanobacterial blooms are common. The goal of the present study is to construct a robust Фe,C model for freshwater ecosystems using simultaneous measurements of ETRPSII by FRRf with multi-excitation wavelengths coupled with a traditional carbon fixation rate by the 13C method. The study was conducted in oligotrophic and mesotrophic parts of Lake Biwa from July 2018 to May 2019. The combination of excitation light at 444, 512 and 633 nm correctly estimated ETRPSII of cyanobacteria. The apparent range of Фe,C in the phytoplankton community was 1.1–31.0 mol e− mol C−1 during the study period. A generalised linear model showed that the best fit including 12 physicochemical and biological factors explained 67% of the variance in Фe,C. Among all factors, water temperature was the most significant, while photosynthetically active radiation intensity was not. This study quantifies the in situ FRRf method in a freshwater ecosystem, discusses core issues in the methodology to calculate Фe,C, and assesses the applicability of the method for lake GPP prediction.


2021 ◽  
Vol 33 (1) ◽  
Author(s):  
Verena Kosfeld ◽  
Heinz Rüdel ◽  
Christian Schlechtriem ◽  
Caren Rauert ◽  
Jan Koschorreck

Abstract Background The trophic magnification factor (TMF) is a metric that describes the average trophic magnification of a chemical through a food web. TMFs may be used for the risk assessment of chemicals, although TMFs for single compounds can vary considerably between studies despite thorough guidance available in the literature to eliminate potential sources of error. The practical realization of a TMF investigation is quite complex and often only a few chemicals can be investigated due to low sample masses. This study evaluated whether a pragmatic approach involving the large-scale cryogenic sample preparation practices of the German Environmental Specimen Bank (ESB) is feasible. This approach could provide sufficient sample masses for a reduced set of samples allowing screenings for a broad spectrum of substances and by that enabling a systematic comparison of derived TMFs. Furthermore, it was assessed whether plausible TMFs can be derived with the ‘Food web on ice’ approach via a comparison with literature TMF values. Results This investigation at Lake Templin near Potsdam is the first TMF study for a German freshwater ecosystem and aimed to derive TMFs that are appropriate for regulatory purposes. A set of 15 composite biota samples was obtained and analyzed for an extended set of benchmark chemicals such as persistent organic pollutants, mercury and perfluoroalkyl substances. TMFs were calculated for all substances that were present in > 80% of the biota samples. For example, in the case of polychlorinated biphenyls, TMFs from 1.7 to 2.5 were determined and comparisons to literature TMFs determined in other freshwater ecosystems showed similarities. We showed that 32 out of 35 compounds analyzed had TMFs significantly above 1. In the remaining three cases, the correlations were not statistically significant. Conclusions The derived food web samples allow for an on-demand analysis and are ready-to-use for additional investigations. Since substances with non-lipophilic accumulation properties were also included in the list of analyzed substances, we conclude that the ‘Food web on ice’ provides samples which could be used to characterize the trophic magnification potential of substances with unknown bioaccumulation properties in the future which in return could be compared directly to the benchmarking patterns provided here.


2020 ◽  
Vol 12 (3) ◽  
pp. 438-441
Author(s):  
Anand Mishra ◽  
Sanjive Shukla ◽  
A. K. Chopra ◽  
Sandeep Shukla ◽  
Harnam Singh Lodhi

The Cladocerans, commonly known as “Water fleas” form a primitive freshwater group of micro crustacean zooplankton of the freshwater ecosystem. They play an important role in the aquatic food chain and also contribute significantly to zooplankton dynamics and secondary productivity in freshwater ecosystems. The animals used in the present study were identified as Simocephalus vetulus with the help of identification keys described by various authors in the previous studies from other parts of India. In the present study, the occurrence of “freshwater tailless flea”, S. vetulus (Crustacea- cladocera) is reported for the first time from freshwater bodies in Haridwar, located in foothills of Shivalik Himalayan region in Uttarakhand. The presence of S. vetulus “tailless water flea” will be helpful as a lab model for the health status of aquatic bodies as well as environmental monitoring.


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