Trophic interactions among the heterotrophic components of plankton in man-made peat pools

<p>Man-made peat pools are permanent freshwater habitats developed due to non-commercial man-made peat extraction. Yet, they have not been widely surveyed in terms of ecosystem functioning, mainly regarding the complexity of heterotrophic components of the plankton. In this study we analysed distribution and trophic interrelations among heterotrophic plankton in man-made peat pools located in different types of peatbogs. We found that peat pools showed extreme differences in environmental conditions that occurred to be important drivers of distribution of microplankton and metazooplankton. Abundance of bacteria and protozoa showed significant differences, whereas metazooplankton was less differentiated in density among peat pools. In all peat pools stress-tolerant species of protozoa and metazoa were dominant. In each peat pool five trophic functional groups were distinguished. The abundance of lower functional trophic groups (bacteria, heterotrophic nanoflagellates (HNF) and ciliates feeding on bacteria and HNF) was weakly influenced by environmental drivers and was highly stable in all peat pool types. Higher fu<span style="text-decoration: underline;">n</span>ctional trophic groups (naupli, omnivorous and carnivorous ciliates, cladocerans, adult copepods and copepodites) were strongly influenced by environmental variables and exhibited lower stability. Our study contributes to comprehensive knowledge of the functioning of peat bogs, as our results have shown that peat pools are characterized by high stability of the lowest trophic levels, which can be crucial for energy transfer and carbon flux through food webs.</p>

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Bacterial productivity and protistan bacterivory in coastal and offshore communities of Lake Erie

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f96-345 ◽

1997 ◽

Vol 54 (4) ◽

pp. 788-799 ◽

Cited By ~ 19

Author(s):

S -J Hwang ◽

R T Heath

Keyword(s):

Carbon Flux ◽

Bacterial Production ◽

Lake Erie ◽

Grazing Rate ◽

Trophic Levels ◽

Heterotrophic Nanoflagellates ◽

Bacterial Productivity ◽

Coastal Site ◽

Filtering Rate ◽

Order Of Magnitude

The importance of protists as bacterivores in a coastal community and an offshore community of Lake Erie was compared during the summer of 1994. Bacterial density, cell size, and empirical conversion factors for bacterial productivity were highly variable at both sites and greater at the coastal site (P < 0.01). Bacterial productivity at the coastal site was 25-50 times higher than at the offshore site. Bacterivory was estimated in situ by fluorescently labeled native bacteria. Per-cell grazing rate and filtering rate for each taxon were routinely determined. Heterotrophic nanoflagellates (HNAN) were the most important protistan bacterivores at the offshore site, while HNAN and ciliates were similarly dominant bacterivores at the coastal site. Mixotrophic bacterivory was important only at the offshore site where Dinobryon was the dominant bacterivore. Bacterial carbon flux through protists was higher at the coastal site by an order of magnitude. Offshore protists grazed virtually the entire bacterial production, while coastal protists usually grazed less than half of the bacterial production. These results suggest that coastal and offshore sites differed fundamentally in the significance of protists to carbon flux through the microbial loop to higher trophic levels.

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Resilience and stability of a pelagic marine ecosystem

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2015.1931 ◽

2016 ◽

Vol 283 (1822) ◽

pp. 20151931 ◽

Cited By ~ 21

Author(s):

Martin Lindegren ◽

David M. Checkley ◽

Mark D. Ohman ◽

J. Anthony Koslow ◽

Ralf Goericke

Keyword(s):

Ecosystem Functioning ◽

Decadal Variability ◽

Current System ◽

Marine Ecosystem ◽

Experimental Studies ◽

Trophic Levels ◽

Environmental Drivers ◽

California Current System ◽

Functional Complementarity ◽

Key Species

The accelerating loss of biodiversity and ecosystem services worldwide has accentuated a long-standing debate on the role of diversity in stabilizing ecological communities and has given rise to a field of research on biodiversity and ecosystem functioning (BEF). Although broad consensus has been reached regarding the positive BEF relationship, a number of important challenges remain unanswered. These primarily concern the underlying mechanisms by which diversity increases resilience and community stability, particularly the relative importance of statistical averaging and functional complementarity. Our understanding of these mechanisms relies heavily on theoretical and experimental studies, yet the degree to which theory adequately explains the dynamics and stability of natural ecosystems is largely unknown, especially in marine ecosystems. Using modelling and a unique 60-year dataset covering multiple trophic levels, we show that the pronounced multi-decadal variability of the Southern California Current System (SCCS) does not represent fundamental changes in ecosystem functioning, but a linear response to key environmental drivers channelled through bottom-up and physical control. Furthermore, we show strong temporal asynchrony between key species or functional groups within multiple trophic levels caused by opposite responses to these drivers. We argue that functional complementarity is the primary mechanism reducing community variability and promoting resilience and stability in the SCCS.

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Explanatory Power for Medical Expert Systems: Studies in the Representation of Causal Relationships for Clinical Consultations

Methods of Information in Medicine ◽

10.1055/s-0038-1635400 ◽

1982 ◽

Vol 21 (03) ◽

pp. 127-136 ◽

Cited By ~ 25

Author(s):

J. W. Wallis ◽

E. H. Shortliffe

Keyword(s):

Explanatory Power ◽

Prototype System ◽

Inference Rules ◽

Medical Expert ◽

Comprehensive Knowledge ◽

Different Types ◽

Medical Expert Systems ◽

Explanation System ◽

Systems Studies

This paper reports on experiments designed to identify and implement mechanisms for enhancing the explanation capabilities of reasoning programs for medical consultation. The goals of an explanation system are discussed, as is the additional knowledge needed to meet these goals in a medical domain. We have focussed on the generation of explanations that are appropriate for different types of system users. This task requires a knowledge of what is complex and what is important; it is further strengthened by a classification of the associations or causal mechanisms inherent in the inference rules. A causal representation can also be used to aid in refining a comprehensive knowledge base so that the reasoning and explanations are more adequate. We describe a prototype system which reasons from causal inference rules and generates explanations that are appropriate for the user.

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Contrasting responses of above- and belowground diversity to multiple components of land-use intensity

Nature Communications ◽

10.1038/s41467-021-23931-1 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Gaëtane Le Provost ◽

Jan Thiele ◽

Catrin Westphal ◽

Caterina Penone ◽

Eric Allan ◽

...

Keyword(s):

Land Use ◽

Forest Cover ◽

Spatial Scales ◽

Biodiversity Loss ◽

Trophic Levels ◽

Land Use Intensity ◽

Trophic Groups ◽

Multiple Components ◽

Belowground Diversity ◽

Landscape Level

AbstractLand-use intensification is a major driver of biodiversity loss. However, understanding how different components of land use drive biodiversity loss requires the investigation of multiple trophic levels across spatial scales. Using data from 150 agricultural grasslands in central Europe, we assess the influence of multiple components of local- and landscape-level land use on more than 4,000 above- and belowground taxa, spanning 20 trophic groups. Plot-level land-use intensity is strongly and negatively associated with aboveground trophic groups, but positively or not associated with belowground trophic groups. Meanwhile, both above- and belowground trophic groups respond to landscape-level land use, but to different drivers: aboveground diversity of grasslands is promoted by diverse surrounding land-cover, while belowground diversity is positively related to a high permanent forest cover in the surrounding landscape. These results highlight a role of landscape-level land use in shaping belowground communities, and suggest that revised agroecosystem management strategies are needed to conserve whole-ecosystem biodiversity.

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The Community of Ecological Opportunities

Evolutionary Community Ecology ◽

10.23943/princeton/9780691088778.003.0002 ◽

2017 ◽

Author(s):

Mark A. McPeek

Keyword(s):

Plant Species ◽

Resource Availability ◽

Intraguild Predation ◽

Species Interactions ◽

Apparent Competition ◽

Predation Pressure ◽

Trophic Levels ◽

Model Species ◽

Pollinator Species ◽

Different Types

This chapter examines ecological opportunities that are available to species in various positions within a biological community, with particular emphasis on identifying the criteria necessary for an ecological opportunity to exist. Before discussing what performance capabilities a species must have to fill different types of ecological opportunities and what is required for invasibility of species into different functional positions in a community, the chapter considers the different frameworks that have been used to model species interactions. It then describes resource and apparent competition to show how resource availability from below and predation pressure from above can affect the types of species that can exploit specifc ecological opportunities. It also analyzes communities with three trophic levels, intraguild predation or omnivory, mutualism, the mechanisms that foster coexistence between one plant species and one pollinator species, and the case of one plant species with multiple pollinators.

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Range extension of the Bengal monitor (Varanus bengalensis) for the Trans-Himalayan Region with an altitude record for monitor lizards

Zootaxa ◽

10.11646/zootaxa.4732.2.10 ◽

2020 ◽

Vol 4732 (2) ◽

pp. 337-340

Author(s):

ASHUTOSH SINGH ◽

BHUPINDER SINGH RANA ◽

MUKESH THAKUR ◽

BASUDEV TRIPATHY ◽

LALIT KUMAR SHARMA ◽

...

Keyword(s):

Body Size ◽

Indian Subcontinent ◽

Distinct Pattern ◽

Wildlife Protection ◽

Western Asia ◽

Monitor Lizard ◽

Different Types ◽

Freshwater Habitats ◽

Desert Areas ◽

Monitor Lizards

The Bengal monitor lizard or Common Indian monitor lizard (Varanus bengalensis Daudin, 1802) is classified as Least Concern under the IUCN and listed under the Schedule-I of the Indian Wildlife Protection Act 1972. Further, the trade of the species is prohibited as the species is listed in Appendix I of CITES. It is widely distributed over Western Asia, the Indian Subcontinent, and Southeast Asia (Koch et al. 2013). It is reported to occupy both terrestrial as well as freshwater habitats from desert areas to floodplains, scrubland to forests, in different types of terrains at elevations below 1500m (Auffenberg 1994; Papenfuss et al. 2010). Body size of individuals varies from 61 to 175 cm from the tip of the snout to the end of the tail (Auffenberg 1994; Losos and Greene, 1998). Adults are generally grey or greenish-grey in color, with a ventral pattern of grey to black crossbars from the chin to the tail. Adult individuals are less contrasting and have a less distinct pattern than younger individuals. The species shows a sexual dimorphism, with males being heavier (around 7.18 to 10 kg) than females which are about 40% smaller in size (Papenfuss et al. 2010).

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An Invasive Mussel (Arcuatula senhousia, Benson 1842) Interacts with Resident Biota in Controlling Benthic Ecosystem Functioning

Journal of Marine Science and Engineering ◽

10.3390/jmse8120963 ◽

2020 ◽

Vol 8 (12) ◽

pp. 963

Author(s):

Guillaume Bernard ◽

Laura Kauppi ◽

Nicolas Lavesque ◽

Aurélie Ciutat ◽

Antoine Grémare ◽

...

Keyword(s):

Nutrient Cycling ◽

Ecosystem Functioning ◽

Atlantic Coast ◽

Sediment Cores ◽

Environmental Drivers ◽

Zostera Noltei ◽

Invasion Stage ◽

Solute Fluxes ◽

Excretion Rates ◽

Invasive Mussel

The invasive mussel Arcuatula senhousia has successfully colonized shallow soft sediments worldwide. This filter feeding mussel modifies sedimentary habitats while forming dense populations and efficiently contributes to nutrient cycling. In the present study, the density of A. senhousia was manipulated in intact sediment cores taken within an intertidal Zostera noltei seagrass meadow in Arcachon Bay (French Atlantic coast), where the species currently occurs at levels corresponding to an early invasion stage. It aimed at testing the effects of a future invasion on (1) bioturbation (bioirrigation and sediment mixing) as well as on (2) total benthic solute fluxes across the sediment–water interface. Results showed that increasing densities of A. senhousia clearly enhanced phosphate and ammonium effluxes, but conversely did not significantly affect community bioturbation rates, highlighting the ability of A. senhousia to control nutrient cycling through strong excretion rates with potential important consequences for nutrient cycling and benthic–pelagic coupling at a broader scale. However, it appears that the variability in the different measured solute fluxes were underpinned by different interactions between the manipulated density of A. senhousia and several faunal and/or environmental drivers, therefore underlining the complexity of anticipating the effects of an invasion process on ecosystem functioning within a realistic context.

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Centrohelid Heliozoans from Freshwater Habitats of Different Types of South Patagonia and Tierra del Fuego, Chile

Inland Water Biology ◽

10.1134/s1995082919010164 ◽

2019 ◽

Vol 12 (1) ◽

pp. 10-20 ◽

Cited By ~ 1

Author(s):

K. I. Prokina ◽

A. P. Mylnikov

Keyword(s):

Tierra Del Fuego ◽

Different Types ◽

Freshwater Habitats ◽

South Patagonia

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ECOLOGICAL STUDY OF THE PEAT BOGS OF EASTERN NORTH AMERICA: III. NOTES ON THE BEHAVIOR OF CHAMAEDAPHNE CALYCULATA

Canadian Journal of Botany ◽

10.1139/b56-018 ◽

1956 ◽

Vol 34 (1) ◽

pp. 197-207 ◽

Cited By ~ 1

Author(s):

Kornelius Lems

Keyword(s):

Ecological Study ◽

The Other ◽

Soil Conditions ◽

Peat Bogs ◽

Eastern North America ◽

Physiological Basis ◽

Chamaedaphne Calyculata ◽

Different Types ◽

The One ◽

The Relationship

This paper presents data and observations concerning Chamaedaphne calyculata (L.) Moench. (Ericaceae). The branching pattern, the longevity of different types of leaves, and features of flowering are shown to be correlated. The relationship between this complex of features and the habitat is studied, and a few speculations are advanced to explain the physiological basis for the behavior of Chamaedaphne. This study is essentially autecological, and it is hoped that it may constitute a link between the study of soil conditions and the response of plant hormones on the one hand, and phytosociological work in peat bogs on the other hand.

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