scholarly journals Habitat and community structure modulate fish interactions in a neotropical clearwater river

2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Lucas T. Nunes ◽  
Renato A. Morais ◽  
Guilherme O. Longo ◽  
José Sabino ◽  
Sergio R. Floeter
Keyword(s):  
Community Structure ◽  
Species Interactions ◽  
Species Abundance ◽  
Habitat Characteristics ◽  
Agonistic Interaction ◽  
Tropical Rivers ◽  
Biological Communities ◽  
Habitat Variation ◽  
Clearwater River ◽  
Fish Interactions

ABSTRACT Species interactions can modulate the diversity and enhance the stability of biological communities in aquatic ecosystems. Despite previous efforts to describe fish interactions in tropical rivers, the role of habitat characteristics, community structure, and trophic traits over these interactions is still poorly understood. To investigate among-habitat variation in substratum feeding pressure and agonistic interactions between fishes, we used remote underwater videos in three habitats of a clearwater river in the Central Western, Brazil. We also performed visual surveys to estimate the abundance and biomass of fishes and proposed a trophic classification to understand how these variables can affect fish interactions. Community structure was the main factor affecting the variation in the interactions among the habitats. Biomass was the main variable determining which habitat a fish will feed on, while species abundance determined with how many other species it will interact in the agonistic interaction networks for each habitat. Specific habitats are not only occupied, but also used in distinct ways by the fish community. Overall, our results demonstrate the importance of the heterogeneity of habitats in tropical rivers for the interactions performed by the fishes and how the intensity of these interactions is affected by community structure.

scholarly journals Influence of European Beech (Fagales: Fagaceae) Rot Hole Habitat Characteristics on Invertebrate Community Structure and Diversity

2021 ◽  
Vol 21 (5) ◽  
Author(s):  
Jordan P Cuff ◽  
Fredric M Windsor ◽  
Emma C Gilmartin ◽  
Lynne Boddy ◽  
T Hefin Jones
Keyword(s):  
Community Structure ◽  
Environmental Conditions ◽  
European Beech ◽  
Habitat Characteristics ◽  
Invertebrate Communities ◽  
Biological Communities ◽  
Β Diversity ◽  
Invertebrate Diversity ◽  
Veteran Trees ◽  
Hole Dimensions

Abstract Hollows of veteran trees (i.e., rot holes) provide habitat for many rare and threatened saproxylic invertebrates. Rot holes are highly heterogeneous, particularly in terms of substrate and microclimate conditions. There is, however, a dearth of information regarding the differences in biological communities inhabiting rot holes with different environmental conditions. Invertebrates were sampled from European beech (Fagus sylvatica) rot holes in Windsor, Savernake, and Epping Forests (United Kingdom). For each rot hole, physical and environmental conditions were measured, including tree diameter, rot hole dimensions, rot hole height, substrate density, water content, and water potential. These parameters were used to assess the influence of environmental conditions and habitat characteristics on invertebrate communities. Rot hole invertebrate communities were extremely diverse, containing both woodland generalist and saproxylic specialist taxa. Large variation in community structure was observed between rot holes and across woodlands; all sites supported threatened and endangered taxa. Environmental conditions in rot holes were highly variable within and between woodland sites, and communities were predominantly structured by these environmental conditions. In particular, turnover between invertebrate communities was linked to high β-diversity. The linked heterogeneity of environmental conditions and invertebrate communities in rot holes suggests that management of deadwood habitats in woodlands should strive to generate environmental heterogeneity to promote invertebrate diversity. Additional research is required to define how management and conservation activities can further promote enhanced biodiversity across rot holes.

Temporal trends in benthic macrofauna composition in response to seasonal variation in a tropical coastal lagoon, Celestun, Gulf of Mexico

2008 ◽  
Vol 59 (9) ◽  
pp. 772 ◽  
Author(s):  
Norma A. Hernández-Guevara ◽  
Daniel Pech ◽  
Pedro-Luis Ardisson
Keyword(s):  
Community Structure ◽  
Coastal Lagoon ◽  
Benthic Community ◽  
Temporal Trends ◽  
Community Response ◽  
Benthic Macrofauna ◽  
Habitat Characteristics ◽  
Physical Factors ◽  
Tropical Coastal Lagoon ◽  
Habitat Variation

Aquatic habitats in some tropical coastal environments can change seasonally, causing changes in the community structure of the benthic macrofauna. A tropical coastal lagoon, the Celestun lagoon, on the north-west Yucatan peninsula, was sampled seasonally and faunal, water and sediment data were compared with conditions during the 1994–1995 weather cycle across a grid of 12 sites distributed along the lagoon’s salinity gradient. Habitat variation was expressed as physical factors associated with the water column (e.g. salinity) and bottom sediments (e.g. interstitial salinity, texture), whereas the benthic community response was assessed through changes in species composition, diversity and dominance. Taxonomic dominance varied according to changes in seasonal habitat characteristics. During the season of strong northerly winds (‘nortes’), molluscs dominated and polychaetes almost disappeared. Polychaetes then recovered during the dry season, becoming as common as crustaceans and molluscs. Finally, during the rainy season, polychaetes became the dominant group and molluscs declined. A conceptual model summarising the community structure changes associated with key physical and biotic factors is proposed. The results indicate that the benthic community of the Celestun lagoon is a resilient one, largely driven by natural weather variability in this tropical ecosystem to a greater extent than previously suggested.

scholarly journals Upstream trophic structure modulates downstream community dynamics via resource subsidies

2016 ◽  
Author(s):  
Eric Harvey ◽  
Isabelle Gounand ◽  
Chelsea Little ◽  
Emanuel A. Fronhofer ◽  
Florian Altermatt
Keyword(s):  
Community Structure ◽  
Species Interactions ◽  
Community Dynamics ◽  
Physical Structure ◽  
Trophic Levels ◽  
Resource Subsidies ◽  
Biological Communities ◽  
Natural Systems ◽  
Resource Flows ◽  
Downstream Communities

AbstractIn many natural systems, the physical structure of the landscape dictates the flow of resources. Despite mounting evidence that communities’ dynamics can be indirectly coupled by reciprocal among-ecosystem resource flows, our understanding of how directional resource flows might indirectly link biological communities is limited. We here propose that differences in community structure upstream should lead to different downstream dynamics, even in the absence of dispersal. We report an experimental test of the effect of upstream community structure on downstream community dynamics in a simplified but highly controlled setting, using protist microcosms. We implemented directional flows of resources, without dispersal, from a standard resource pool into upstream communities of contrasting interaction structure and then to further downstream communities of either one or two trophic levels. Our results demonstrate that different types of species interactions in upstream habitats may lead to different population sizes and levels of biomass in these upstream habitats. This, in turn, leads to varying levels of detritus transfer (dead biomass) to the downstream communities, thus influencing their population densities and trophic interactions in predictable ways. Our results suggest that the structure of species interactions in directionally structured ecosystems can be a key mediator of alterations to downstream habitats. Alterations to upstream habitats can thus cascade down to downstream communities, even without dispersal.

Benthic species as mud patrol - modelled effects of bioturbators and biofilms on large-scale estuarine mud and morphology

2021 ◽  
Author(s):  
Muriel Brückner ◽  
Christian Schwarz ◽  
Giovanni Coco ◽  
Anne Baar ◽  
Márcio Boechat Albernaz ◽  
...  
Keyword(s):  
Morphological Change ◽  
Species Interactions ◽  
Large Scale ◽  
Habitat Degradation ◽  
Species Abundance ◽  
Estuarine Sediments ◽  
Morphological Development ◽  
Benthic Species ◽  
Species Dominance ◽  
Species Specific

<p>Benthic species that live within estuarine sediments stabilize or destabilize local mud deposits through their eco-engineering activities, affecting the erosion of intertidal sediments. Possibly, the altered magnitudes in eroded sediment affect the large-scale redistribution of fines and hence morphological change. To quantify this biological control on the morphological development of estuaries, we numerically model i) biofilms, ii) two contrasting bioturbating species present in NW-Europe, and iii) their combinations by means of our novel eco-morphodynamic model. The model predicts local mud erodibility based on species pattern, which dynamically evolves from the hydrodynamics, soil mud content, competition and grazing, and is fed back into the hydromorphodynamic computations.</p><p>We find that biofilms reduce mud erosion on intertidal floodplains and stabilize estuarine morphology, whereas the two bioturbators significantly enhance inter- and supratidal mud erosion and bed elevation change, leading to a large-scale reduction in deposited mud and a widening of the estuary. In turn, the species-dependent changes in mud content redefines their habitat and leads to a redistribution of species abundances. Here, the eco-engineering affects habitat conditions and species abundance while species interactions determine species dominance. Our results show that species-specific biostabilization and bioturbation determine large-scale morphological change through mud redistribution, and at the same time affect species distribution. This suggests that benthic species have subtly changed estuarine morphology through space and time and that aggravating habitat degradation might lead to large effects on the morphology of future estuaries.</p>

scholarly journals The emergent interactions that govern biodiversity change

2020 ◽  
Vol 117 (29) ◽  
pp. 17074-17083 ◽  
Author(s):  
James S. Clark ◽  
C. Lane Scher ◽  
Margaret Swift
Keyword(s):  
Species Interactions ◽  
Environmental Gradients ◽  
Local Population ◽  
Species Abundance ◽  
Community Change ◽  
Model Specification ◽  
Data Simulation ◽  
Breeding Bird ◽  
Probabilistic Uncertainty ◽  
Nonlinear Responses

Observational studies have not yet shown that environmental variables can explain pervasive nonlinear patterns of species abundance, because those patterns could result from (indirect) interactions with other species (e.g., competition), and models only estimate direct responses. The experiments that could extract these indirect effects at regional to continental scales are not feasible. Here, a biophysical approach quantifies environment– species interactions (ESI) that govern community change from field data. Just as species interactions depend on population abundances, so too do the effects of environment, as when drought is amplified by competition. By embedding dynamic ESI within framework that admits data gathered on different scales, we quantify responses that are induced indirectly through other species, including probabilistic uncertainty in parameters, model specification, and data. Simulation demonstrates that ESI are needed for accurate interpretation. Analysis demonstrates how nonlinear responses arise even when their direct responses to environment are linear. Applications to experimental lakes and the Breeding Bird Survey (BBS) yield contrasting estimates of ESI. In closed lakes, interactions involving phytoplankton and their zooplankton grazers play a large role. By contrast, ESI are weak in BBS, as expected where year-to-year movement degrades the link between local population growth and species interactions. In both cases, nonlinear responses to environmental gradients are induced by interactions between species. Stability analysis indicates stability in the closed-system lakes and instability in BBS. The probabilistic framework has direct application to conservation planning that must weigh risk assessments for entire habitats and communities against competing interests.

scholarly journals Community structure of tenebrionid beetles in the Ulan Buh Desert (Inner Mongolia, China) (Coleoptera: Tenebrionidae)

2019 ◽  
Vol 51 (2) ◽  
pp. 193-200 ◽  
Author(s):  
Yiping Niu ◽  
Guodong Ren ◽  
Giulia Lin ◽  
Letizia Di Biase ◽  
Simone Fattorini
Keyword(s):  
Community Structure ◽  
Plant Cover ◽  
Species Abundance ◽  
Local Environment ◽  
Gobi Desert ◽  
Similar Species ◽  
Abundance Patterns ◽  
Central Asian ◽  
Species Abundance Distributions ◽  
Ulan Buh Desert

Tenebrionids are a conspicuous faunal component of Central Asian deserts, but little is known about their community ecology. We investigated how tenebrionid community structure varied along a vegetational gradient in the Ulan Buh Desert (Gobi Desert). Sampling was done with pitfall traps in three sites with different vegetation cover. Species abundance distributions were fitted by the geometric series model, which expresses the “niche pre-emption” hypothesis. Community structure was investigated using different measures of diversity (number of species, Margaleff richness and Shannon-Weaner index), dominance (Simpson and Berger-Parker indexes) and evenness (Pielou’s index). The observed tenebrionid species richness was similar to that known from other Gobi Desert sites. The three investigated sites have similar species-abundance patterns, but the most dominant species varied among them. This suggests that the local environment operates a filtering action on the same basic fauna, allowing different species to dominate under different conditions. Overall, the highest total abundance was observed in the true desert site, however this site had a community structure similar to that observed in the site with more vegetation. By contrast, the investigated site with intermediate conditions showed a higher diversity and evenness, and a lower dominance. Thus, intermediate conditions of plant cover favour tenebrionid diversity, whereas a dense cover or a very sparse cover increases the dominance.

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