A Metacommunity Approach to Improve Biological Assessments in Highly Dynamic Freshwater Ecosystems

Abstract Rapid shifts in biotic communities due to environmental variability challenge the detection of anthropogenic impacts by current biomonitoring programs. Metacommunity ecology has the potential to inform such programs, because it combines dispersal processes with niche-based approaches and recognizes variability in community composition. Using intermittent rivers—prevalent and highly dynamic ecosystems that sometimes dry—we develop a conceptual model to illustrate how dispersal limitation and flow intermittence influence the performance of biological indices. We produce a methodological framework integrating physical- and organismal-based dispersal measurements into predictive modeling, to inform development of dynamic ecological quality assessments. Such metacommunity-based approaches could be extended to other ecosystems and are required to underpin our capacity to monitor and protect ecosystems threatened under future environmental changes.

Download Full-text

Population decline of the cape petrel (Daption capense) on King George Island, South Shetland Islands, Antarctica

Polar Biology ◽

10.1007/s00300-021-02914-4 ◽

2021 ◽

Author(s):

Christina Braun ◽

Jan Esefeld ◽

Larisa Savelieva ◽

Hans-Ulrich Peter

Keyword(s):

Environmental Changes ◽

Environmental Variability ◽

Anthropogenic Impacts ◽

Population Decline ◽

Monitoring Program ◽

South Shetland Islands ◽

Fildes Peninsula ◽

Breeding Sites ◽

Shetland Islands

AbstractThe Antarctic and the surrounding Southern Ocean are currently subject to rapid environmental changes and increasing anthropogenic impacts. Seabird populations often reflect those changes and so act as indicators of environmental variability. Their population trends may provide information on a variety of environmental parameters on the scale of years or decades. We therefore provide long-term data on the cape petrel (Daption capense) population from a long-term monitoring program on Fildes Peninsula, South Shetland Islands, Maritime Antarctic, an area of considerable human activity. Our data, covering a period of 36 years, indicate some variability, but no clear trend in the number of breeding pairs between the breeding seasons 1985 and 2006. However, beginning in the 2008 season, the population decreased significantly and reached a minimum in the 2020 season. The mean annual decrease between 2008 and 2020 was 10.6%. We discuss possible causes of this strong negative population trend. Anthropogenic disturbance only affects a few breeding sites in the area and is therefore unable, on its own, to explain the consistent population decline at all the breeding sites studied. We think it more likely that reduced food availability was the main cause of the drastic decline in the cape petrel population.

Download Full-text

Organic geochemical characterization of Early-Mid-Holocene swamp deposits near the Neolithic settlement in Yenikapı-Istanbul: Assessment of environmental variability and anthropogenic impacts

The Holocene ◽

10.1177/09596836211033197 ◽

2021 ◽

pp. 095968362110331

Author(s):

Mehmet Namık Yalçın ◽

Heinz Wilkes ◽

Birgit Plessen

Keyword(s):

Organic Matter ◽

Environmental Changes ◽

Environmental Variability ◽

Anthropogenic Impacts ◽

Hydrological Regime ◽

Climatic Conditions ◽

Neolithic Period ◽

Age Model ◽

Isotopic Characterization

During the archaeological excavations in the Byzantine Theodosian harbor (Istanbul) a Holocene dark gray to black clay sequence was uncovered. This clay unit was deposited under anoxic conditions in a small swamp. Both wooden artifacts from the Neolithic period, but also dispersed organic matter were perfectly preserved within this sequence. The aim of this study was the assessment of environmental changes and anthropogenic impacts with the help of organic geochemical and isotopic characterization of organic matter in this clay unit. The age model, based on 14C data, showed that the clay was deposited during a period about from 11,100 to 7500 cal. years BP. Hydrogen Index values lower than 100 mgHC/gTOC, n-alkane distributions with maxima at nC29 or at nC31, a predominance of long-chain n-alkanes (C25–C33) and δ13Corg values around −24‰ to −27‰ suggest a predominantly terrestrial origin of organic matter from C3 plants. Obvious excursions of bulk δ13Corg and compound-specific δ13C and δD values of nC27, nC29, nC31, and nC33 are interpreted as indicators of changes in environmental and climatic conditions. Several shifts toward colder and warmer climatic conditions were identified and dated. Furthermore, two sudden changes in the hydrological regime were dated to 9000–8820 cal. years BP and to 8150–8050 cal. years BP toward wetter and drier conditions, respectively. Specific molecular organic geochemical indicators such as faecal sterols or a strong enrichment of δ15N caused by human impact could not be detected. Therefore, the swamp should not have been intensively affected by Neolithic people and/or respective indicators of their influence have been diluted due to the high sedimentation rate.

Download Full-text

Climate and environmental context of the Mongol invasion of Syria and defeat at ‘Ayn Jālūt (1258–1260 CE)

Erdkunde ◽

10.3112/erdkunde.2021.02.02 ◽

2021 ◽

Vol 75 (2) ◽

pp. 87-104

Author(s):

Nicola Di Cosmo ◽

Sebastian Wagner ◽

Ulf Büntgen

Keyword(s):

Strategic Alliances ◽

Turning Point ◽

Environmental Changes ◽

Environmental Variability ◽

State Of The Art ◽

Eastern Mediterranean ◽

The Caucasus ◽

Mountainous Regions ◽

The Past ◽

Climate Reconstructions

After a successful conquest of large parts of Syria in 1258 and 1259 CE, the Mongol army lost the battle of 'Ayn Jālūt against Mamluks on September 3, 1260 CE. Recognized as a turning point in world history, their sudden defeat triggered the reconfiguration of strategic alliances and geopolitical power not only in the Middle East, but also across much of Eurasia. Despite decades of research, scholars have not yet reached consensus over the causes of the Mongol reverse. Here, we revisit previous arguments in light of climate and environmental changes in the aftermath of one the largest volcanic forcings in the past 2500 years, the Samalas eruption ~1257 CE. Regional tree ring-based climate reconstructions and state-of-the-art Earth System Model simulations reveal cooler and wetter conditions from spring 1258 to autumn 1259 CE for the eastern Mediterranean/Arabian region. We therefore hypothesize that the post-Samalas climate anomaly and associated environmental variability affected an estimated 120,000 Mongol soldiers and up to half a million of their horses during the conquest. More specifically, we argue that colder and wetter climates in 1258 and 1259 CE, while complicating and slowing the campaign in certain areas, such as the mountainous regions in the Caucasus and Anatolia, also facilitated the assault on Syria between January and March 1260. A return to warmer and dryer conditions in the summer of 1260 CE, however, likely reduced the regional carrying capacity and may therefore have forced a mass withdrawal of the Mongols from the region that contributed to the Mamluks’ victory. In pointing to a distinct environmental dependency of the Mongols, we offer a new explanation of their defeat at 'Ayn Jālūt, which effectively halted the further expansion of the largest ever land-based empire.

Download Full-text

Monitoring studies should consider temporal variability to reveal relations between cyanobacterial abundance and environmental variables

Anais da Academia Brasileira de Ciências ◽

10.1590/0001-3765201520140416 ◽

2015 ◽

Vol 87 (3) ◽

pp. 1717-1726 ◽

Cited By ~ 3

Author(s):

JULIANA WOJCIECHOWSKI ◽

ANDRÉ A. PADIAL

Keyword(s):

Temporal Variability ◽

Environmental Variables ◽

Environmental Changes ◽

Environmental Variability ◽

Time Lag ◽

Cyanobacteria Blooms ◽

Environment Variables ◽

Sampling Points ◽

The Relationship

One of the main goals of monitoring cyanobacteria blooms in aquatic environments is to reveal the relationship between cyanobacterial abundance and environmental variables. Studies typically correlate data that were simultaneously sampled. However, samplings occur sparsely over time and may not reveal the short-term responses of cyanobacterial abundance to environmental changes. In this study, we tested the hypothesis that stronger cyanobacteria x environment relationships in monitoring are found when the temporal variability of sampling points is incorporated in the statistical analyses. To this end, we investigated relationships between cyanobacteria and seven environmental variables that were sampled twice yearly for three years across 11 reservoirs, and data from an intensive monitoring in one of these reservoirs. Poor correlations were obtained when correlating data simultaneously sampled. In fact, the 'highly recurrent' role of phosphorus in cyanobacteria blooms is not properly observed in all sampling periods. On the other hand, the strongest correlation values for the total phosphorus x cyanobacteria relationship were observed when we used the variation of sampling points. We have also shown that environment variables better explain cyanobacteria when a time lag is considered. We conclude that, in cyanobacteria monitoring, the best approach to reveal determinants of cyanobacteria blooms is to consider environmental variability.

Download Full-text

Habitat choice meets thermal specialization: Competition with specialists may drive suboptimal habitat preferences in generalists

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1805574115 ◽

2018 ◽

Vol 115 (47) ◽

pp. 11988-11993 ◽

Cited By ~ 13

Author(s):

Staffan Jacob ◽

Estelle Laurent ◽

Bart Haegeman ◽

Romain Bertrand ◽

Jérôme G. Prunier ◽

...

Keyword(s):

Environmental Changes ◽

Environmental Variability ◽

Habitat Preferences ◽

Habitat Choice ◽

Current Theory ◽

Ecological Specialization ◽

Metapopulation Model ◽

Niche Specialization ◽

Random Dispersal ◽

Limited Dispersal

Limited dispersal is classically considered as a prerequisite for ecological specialization to evolve, such that generalists are expected to show greater dispersal propensity compared with specialists. However, when individuals choose habitats that maximize their performance instead of dispersing randomly, theory predicts dispersal with habitat choice to evolve in specialists, while generalists should disperse more randomly. We tested whether habitat choice is associated with thermal niche specialization using microcosms of the ciliate Tetrahymena thermophila, a species that performs active dispersal. We found that thermal specialists preferred optimal habitats as predicted by theory, a link that should make specialists more likely to track suitable conditions under environmental changes than expected under the random dispersal assumption. Surprisingly, generalists also performed habitat choice but with a preference for suboptimal habitats. Since this result challenges current theory, we developed a metapopulation model to understand under which circumstances such a preference for suboptimal habitats should evolve. We showed that competition between generalists and specialists may favor a preference for niche margins in generalists under environmental variability. Our results demonstrate that the behavioral dimension of dispersal—here, habitat choice—fundamentally alters our predictions of how dispersal evolve with niche specialization, making dispersal behaviors crucial for ecological forecasting facing environmental changes.

Download Full-text

The influence of a lost society, the Sadlermiut, on the environment in the Canadian Arctic

Scientific Reports ◽

10.1038/s41598-021-97631-7 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Finn A. Viehberg ◽

Andrew S. Medeiros ◽

Birgit Plessen ◽

Xiaowa Wang ◽

Derek Muir ◽

...

Keyword(s):

High Latitude ◽

Anthropogenic Impacts ◽

Archaeological Site ◽

Biological Indicators ◽

Benthic Invertebrate ◽

Freshwater Ecosystems ◽

Environmental Implications ◽

Dietary Shift ◽

Freshwater Pond ◽

First Arrival

AbstractHigh latitude freshwater ecosystems are sentinels of human activity and environmental change. The lakes and ponds that characterize Arctic landscapes have a low resilience to buffer variability in climate, especially with increasing global anthropogenic stressors in recent decades. Here, we show that a small freshwater pond in proximity of the archaeological site “Native Point” on Southampton Island (Nunavut, Arctic Canada) is a highly sensitive environmental recorder. The sediment analyses allowed for pinpointing the first arrival of Sadlermiut culture at Native Point to ~ 1250 CE, followed by a dietary shift likely in response to the onset of cooling in the region ~ 1400 CE. The influence of the Sadlermiut on the environment persisted long after the last of their population perished in 1903. Presently, the pond remains a distorted ecosystem that has experienced fundamental shifts in the benthic invertebrate assemblages and accumulated anthropogenic metals in the sediment. Our multi-proxy paleolimnological investigation using geochemical and biological indicators emphasizes that direct and indirect anthropogenic impacts have long-term environmental implications on high latitude ecosystems.

Download Full-text

Freshwater nematodes as bioindicators in field studies - the NemaSPEAR[%]-index.

Ecology of freshwater nematodes ◽

10.1079/9781789243635.0011 ◽

2021 ◽

pp. 323-340

Author(s):

Sebastian Höss ◽

Walter Traunspurger

Keyword(s):

Ecological Status ◽

Nematode Species ◽

Field Studies ◽

Freshwater Ecosystems ◽

Freshwater Nematodes ◽

Chemically Induced ◽

Freshwater Habitats ◽

Induced Changes ◽

Quality Assessments

Abstract This chapter, after a general introduction to quality assessments of freshwater habitats, reviews the use of freshwater nematodes as in situ bioindicators, including in monitoring the ecological quality of freshwater habitats. By drawing on studies of nematode communities in unpolluted and polluted habitats as examples, it highlights both the different methods used to assess the quality of freshwater ecosystems and their applications. A focus of the chapter is the development of a new index that uses freshwater nematodes to assess chemically induced changes in the ecological status of freshwater habitats, the NemaSPEAR[%]-index (Nematode SPEcies At Risk).

Download Full-text

Monitoring spawning migrations of potamodromous fish species via eDNA

Scientific Reports ◽

10.1038/s41598-019-51398-0 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 11

Author(s):

Bettina Thalinger ◽

Elisabeth Wolf ◽

Michael Traugott ◽

Josef Wanzenböck

Keyword(s):

Fish Species ◽

Anthropogenic Impacts ◽

Environmental Dna ◽

Signal Strength ◽

Digital Pcr ◽

Freshwater Ecosystems ◽

Non Invasive ◽

River Stretch ◽

Daily Discharge ◽

Invasive Techniques

Abstract Potamodromous fish are considered important indicators of habitat connectivity in freshwater ecosystems, but they are globally threatened by anthropogenic impacts. Hence, non-invasive techniques are necessary for monitoring during spawning migrations. The use of environmental DNA (eDNA) potentially facilitates these efforts, albeit quantitative examinations of spawning migrations remain so far mostly uncharted. Here, we investigated spawning migrations of Danube bleak, Alburnus mento, and Vimba bream, Vimba vimba, and found a strong correlation between daily visual fish counts and downstream eDNA signals obtained from filtered water samples analysed with digital PCR and end-point PCR coupled with capillary electrophoresis. By accounting for daily discharge fluctuations, it was possible to predict eDNA signal strength from the number of migrating fish: first, the whole spawning reach was taken into account. Second, the model was validated using eDNA signals and fish counts obtained from the upper half of the examined river stretch. Consequently, fish counts and their day-to-day changes could be described via an eDNA-based time series model for the whole migration period. Our findings highlight the capability of eDNA beyond delivering simple presence/absence data towards efficient and informative monitoring of highly dynamic aquatic processes such as spawning migrations of potamodromous fish species.

Download Full-text

Climatic changes cause synchronous population dynamics and adaptive strategies among coastal hunter-gatherers in Holocene northern Europe

Quaternary Research ◽

10.1017/qua.2019.86 ◽

2020 ◽

pp. 1-16 ◽

Cited By ~ 2

Author(s):

Erlend Kirkeng Jørgensen ◽

Petro Pesonen ◽

Miikka Tallavaara

Keyword(s):

Population Dynamics ◽

Environmental Changes ◽

Environmental Variability ◽

Temporal Frequency ◽

Environmental Drivers ◽

Natural Phenomenon ◽

Northern Europe ◽

Human Populations ◽

Hunter Gatherers ◽

Human Ecodynamics

Abstract Synchronized demographic and behavioral patterns among distinct populations is a well-known, natural phenomenon. Intriguingly, similar patterns of synchrony occur among prehistoric human populations. However, the drivers of synchronous human ecodynamics are not well understood. Addressing this issue, we review the role of environmental variability in causing human demographic and adaptive responses. As a case study, we explore human ecodynamics of coastal hunter-gatherers in Holocene northern Europe, comparing population, economic, and environmental dynamics in two separate areas (northern Norway and western Finland). Population trends are reconstructed using temporal frequency distributions of radiocarbon-dated and shoreline-dated archaeological sites. These are correlated to regional environmental proxies and proxies for maritime resource use. The results demonstrate remarkably synchronous patterns across population trajectories, marine resource exploitation, settlement pattern, and technological responses. Crucially, the population dynamics strongly correspond to significant environmental changes. We evaluate competing hypotheses and suggest that the synchrony stems from similar responses to shared environmental variability. We take this to be a prehistoric human example of the “Moran effect,” positing similar responses of geographically distinct populations to shared environmental drivers. The results imply that intensified economies and social interaction networks have limited impact on long-term hunter-gatherer population trajectories beyond what is already proscribed by environmental drivers.

Download Full-text

Inhibition of Extracellular Enzymes Exposed to Cyanopeptides

CHIMIA International Journal for Chemistry ◽

10.2533/chimia.2020.122 ◽

2020 ◽

Vol 74 (3) ◽

pp. 122-128

Author(s):

Christine M. Egli ◽

Regiane S. Natumi ◽

Martin R. Jones ◽

Elisabeth M.-L. Janssen

Keyword(s):

Extracellular Enzymes ◽

Heterotrophic Bacteria ◽

Hydrolytic Enzymes ◽

Aquatic Organisms ◽

Freshwater Ecosystems ◽

Cyanobacterial Blooms ◽

Biologically Relevant ◽

Metabolic Functions ◽

Harmful Cyanobacterial Blooms ◽

Quality Assessments

Harmful cyanobacterial blooms in freshwater ecosystems produce bioactive secondary metabolites including cyanopeptides that pose ecological and human health risks. Only adverse effects of one class of cyanopeptides, microcystins, have been studied extensively and have consequently been included in water quality assessments. Inhibition is a commonly observed effect for enzymes exposed to cyanopeptides and has mostly been investigated for human biologically relevant model enzymes. Here, we investigated the inhibition of ubiquitous aquatic enzymes by cyanobacterial metabolites. Hydrolytic enzymes are utilized in the metabolism of aquatic organisms and extracellularly by heterotrophic bacteria to obtain assimilable substrates. The ubiquitous occurrence of hydrolytic enzymes leads to the co-occurrence with cyanopeptides especially during cyanobacterial blooms. Bacterial leucine aminopeptidase and alkaline phosphatase were exposed to cyanopeptide extracts of different cyanobacterial strains ( Microcystis aeruginosa wild type and microcystin-free mutant, Planktothrix rubescens) and purified cyanopeptides. We observed inhibition of aminopeptidase and phosphatase upon exposure, especially to the apolar fractions of the cyanobacterial extracts. Exposure to the dominant cyanopeptides in these extracts confirmed that purified microcystins, aerucyclamide A and cyanopeptolin A inhibit the aminopeptidase in the low mg L–1 range while the phosphatase was less affected. Inhibition of aquatic enzymes can reduce the turnover of nutrients and carbon substrates and may also impair metabolic functions of grazing organisms.

Download Full-text