Role of nematodes in the food web: nematodes as predator and prey.

Ecology of freshwater nematodes ◽

10.1079/9781789243635.0007 ◽

2021 ◽

pp. 216-246

Author(s):

Christoph Ptatscheck

Keyword(s):

Food Web ◽

Functional Response ◽

Trophic Interactions ◽

Individual Species ◽

Energy Fluxes ◽

Direct Observations ◽

Microcosm Studies

Abstract This chapter provides information on the role of nematodes in the food web, including their participation in matter and energy fluxes within ecosystems. It highlights that nematodes are both predators and prey for organisms ranging from protozoans to vertebrates, based on gut analyses and direct observations. Functional response experiments, microcosm studies, and enclosures/exclosures in the field can be used to investigate the intensity of these trophic interactions and their impact on individual species as well as entire communities.

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Host-parasitoid associations in marine planktonic time series: Can metabarcoding help reveal them?

PLoS ONE ◽

10.1371/journal.pone.0244817 ◽

2021 ◽

Vol 16 (1) ◽

pp. e0244817

Author(s):

Laura Käse ◽

Katja Metfies ◽

Stefan Neuhaus ◽

Maarten Boersma ◽

Karen Helen Wiltshire ◽

...

Keyword(s):

Time Series ◽

Food Web ◽

Individual Species ◽

Research Station ◽

Ecological Research ◽

Operational Taxonomic Units ◽

Long Term Ecological Research ◽

High Dynamics

In this study, we created a dataset of a continuous three-year 18S metabarcoding survey to identify eukaryotic parasitoids, and potential connections to hosts at the Long-Term Ecological Research station Helgoland Roads. The importance of parasites and parasitoids for food web dynamics has previously been recognized mostly in terrestrial and freshwater systems, while marine planktonic parasitoids have been understudied in comparison to those. Therefore, the occurrence and role of parasites and parasitoids remains mostly unconsidered in the marine environment. We observed high abundances and diversity of parasitoid operational taxonomic units in our dataset all year round. While some parasitoid groups were present throughout the year and merely fluctuated in abundances, we also detected a succession of parasitoid groups with peaks of individual species only during certain seasons. Using co-occurrence and patterns of seasonal occurrence, we were able to identify known host-parasitoid dynamics, however identification of new potential host-parasitoid interactions was not possible due to their high dynamics and variability in the dataset.

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HEAT TRANSPORT IN SALT FLATS: THE ROLE OF THE LAND-SURFACE ENERGY FLUXES IN DEEP SUBSURFACE TEMPERATURE DISTRIBUTIONS

10.1130/abs/2018am-322934 ◽

2018 ◽

Author(s):

Graham Thomas ◽

◽

David F. Boutt ◽

LeeAnn Munk

Keyword(s):

Surface Energy ◽

Heat Transport ◽

Land Surface ◽

Subsurface Temperature ◽

Energy Fluxes ◽

Deep Subsurface ◽

Surface Energy Fluxes ◽

Temperature Distributions ◽

Salt Flats

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Functional response of Harmonia axyridis preying on Acyrthosiphon pisum nymphs: the effect of temperature

Scientific Reports ◽

10.1038/s41598-021-92954-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Yasir Islam ◽

Farhan Mahmood Shah ◽

Xu Rubing ◽

Muhammad Razaq ◽

Miao Yabo ◽

...

Keyword(s):

Functional Response ◽

High Performance ◽

Acyrthosiphon Pisum ◽

Harmonia Axyridis ◽

Effect Of Temperature ◽

Functional Responses ◽

Aphid Control ◽

Host Aphid ◽

Predator Foraging

AbstractIn the current study, we investigated the functional response of Harmonia axyridis adults and larvae foraging on Acyrthosiphon pisum nymphs at temperatures between 15 and 35 °C. Logistic regression and Roger’s random predator models were employed to determine the type and parameters of the functional response. Harmonia axyridis larvae and adults exhibited Type II functional responses to A. pisum, and warming increased both the predation activity and host aphid control mortality. Female and 4th instar H. axyridis consumed the most aphids. For fourth instar larvae and female H. axyridis adults, the successful attack rates were 0.23 ± 0.014 h−1 and 0.25 ± 0.015 h−1; the handling times were 0.13 ± 0.005 h and 0.16 ± 0.004 h; and the estimated maximum predation rates were 181.28 ± 14.54 and 153.85 ± 4.06, respectively. These findings accentuate the high performance of 4th instar and female H. axyridis and the role of temperature in their efficiency. Further, we discussed such temperature-driven shifts in predation and prey mortality concerning prey-predator foraging interactions towards biological control.

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Lyell, the Geikies and Croll's observations on terrestrial glacial sediments and landforms

Earth and Environmental Science Transactions of the Royal Society of Edinburgh ◽

10.1017/s1755691021000116 ◽

2021 ◽

pp. 1-14

Author(s):

James ROSE

Keyword(s):

Climate Change ◽

High Quality ◽

Glacial Sediments ◽

Direct Observations ◽

The Social ◽

The Status ◽

Social And Physical Environment ◽

Glacial Landforms

ABSTRACT Within the context of the work and achievements of James Croll, this paper reviews the records of direct observations of glacial landforms and sediments made by Charles Lyell, Archibald and James Geikie and James Croll himself, in order to evaluate their contributions to the sciences of glacial geology and Quaternary environmental change. The paper outlines the social and physical environment of Croll's youth and contrasts this with the status and experiences of Lyell and the Geikies. It also outlines the character and role of the ‘Glasgow School’ of geologists, who stimulated Croll's interest into the causes of climate change and directed his focus to the glacial and ‘interglacial’ deposits of central Scotland. Contributions are outlined in chronological order, drawing attention to: (i) Lyell's high-quality observations and interpretations of glacial features in Glen Clova and Strathmore and his subsequent rejection of the glacial theory in favour of processes attributed to floating icebergs; (ii) the significant impact of Archibald Geikie's 1863 paper on the ‘glacial drift of Scotland’, which firmly established the land-ice theory; (iii) the fact that, despite James Croll's inherent dislike of geology and fieldwork, he provided high-quality descriptions and interpretations of the landforms and sediments of central Scotland in order to test his theory of climate change; and (iv) the great communication skills of James Geikie, enhanced by contacts and evidence from around the world. It is concluded that whilst direct observations of glacial landforms and sediments were critical to the long-term development of the study of glaciation, the acceptance of this theory was dependent also upon the skills, personality and status of the Geikies and Croll, who developed and promoted the concepts. Sadly, the subsequent rejection of the land-ice concept by Lyell resulted in the same factors challenging the acceptance of the glacial theory.

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Trophic interactions and food web structure of aquatic macroinvertebrate communities in afromontane wetlands: the influence of hydroperiod

Aquatic Sciences ◽

10.1007/s00027-021-00792-w ◽

2021 ◽

Vol 83 (2) ◽

Author(s):

Nonkazimulo D. Mdidimba ◽

Musa C. Mlambo ◽

Samuel N. Motitsoe

Keyword(s):

Food Web ◽

Trophic Interactions ◽

Macroinvertebrate Communities ◽

Food Web Structure ◽

Aquatic Macroinvertebrate ◽

Web Structure ◽

Aquatic Macroinvertebrate Communities

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The food web in a subterranean ecosystem is driven by intraguild predation

Scientific Reports ◽

10.1038/s41598-021-84521-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Andrea Parimuchová ◽

Lenka Petráková Dušátková ◽

Ľubomír Kováč ◽

Táňa Macháčková ◽

Ondřej Slabý ◽

...

Keyword(s):

Food Web ◽

Trophic Interactions ◽

Intraguild Predation ◽

Linear Models ◽

Niche Overlap ◽

Trophic Niche ◽

High Availability ◽

Large Prey ◽

Arthropod Predators ◽

Body Sizes

AbstractTrophic interactions of cave arthropods have been understudied. We used molecular methods (NGS) to decipher the food web in the subterranean ecosystem of the Ardovská Cave (Western Carpathians, Slovakia). We collected five arthropod predators of the species Parasitus loricatus (gamasid mites), Eukoenenia spelaea (palpigrades), Quedius mesomelinus (beetles), and Porrhomma profundum and Centromerus cavernarum (both spiders) and prey belonging to several orders. Various arthropod orders were exploited as prey, and trophic interactions differed among the predators. Linear models were used to compare absolute and relative prey body sizes among the predators. Quedius exploited relatively small prey, while Eukoenenia and Parasitus fed on relatively large prey. Exploitation of eggs or cadavers is discussed. In contrast to previous studies, Eukoenenia was found to be carnivorous. A high proportion of intraguild predation was found in all predators. Intraspecific consumption (most likely cannibalism) was detected only in mites and beetles. Using Pianka’s index, the highest trophic niche overlaps were found between Porrhomma and Parasitus and between Centromerus and Eukoenenia, while the lowest niche overlap was found between Parasitus and Quedius. Contrary to what we expected, the high availability of Diptera and Isopoda as a potential prey in the studied system was not corroborated. Our work demonstrates that intraguild diet plays an important role in predators occupying subterranean ecosystems.

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