Opportunistic top predators partition food resources in a tropical freshwater ecosystem

2017 ◽  
Vol 62 (8) ◽  
pp. 1389-1400 ◽  
Author(s):  
Francisco Villamarín ◽  
Timothy D. Jardine ◽  
Stuart E. Bunn ◽  
Boris Marioni ◽  
William E. Magnusson
2018 ◽  
Vol 108 (0) ◽  
Author(s):  
Silvia B. Barreto ◽  
André T. Silva ◽  
Fabiane B. Souza ◽  
Ricardo Jucá-Chagas

ABSTRACT Studies on the composition of fish diet and on how species exploit food resources are especially relevant in tropical freshwater systems, where dietary plasticity is a commonly used strategy. In this study, we analysed the food spectrum and the environmental, seasonal and ontogenetic variations in the diet of a characid species [Hemigrammus marginatus Ellis, 1911 (Characidae)] in the region of the Upper Contas River, in the Diamantina Plateau, Brazil. We verified an omnivorous/invertivorous and opportunistic food habit, with predominance of insects and microcrustaceans, followed by filamentous algae. Seasonality did not alter the food resources used by the species. However, differences were detected in the dominant categories when comparing the two sampled rivers, as well as in the food consumption throughout the development of the species. These data increase the knowledge about the biology of H. marginatus and allow understanding the influence of the characteristics of the rivers and their surroundings in the trophic ecology of the species, as our findings have shown that, although insects have been expressive in both studied localities, microcrustaceans exhibit a greater relative importance in the more lentic environment, which is probably related to the variation in the availability of these resources in the environment.


2008 ◽  
Vol 43 (2) ◽  
pp. 249-263 ◽  
Author(s):  
Luis Zambrano ◽  
Victoria Contreras ◽  
Marisa Mazari-Hiriart ◽  
Alba E. Zarco-Arista

2019 ◽  
Vol 39 (4) ◽  
pp. 516-521
Author(s):  
Adeline Y P Yong ◽  
Shirley S L Lim

ABSTRACT Ghost crabs, OcypodeWeber, 1795 (Decapoda: Brachyura: Ocypodidae) are the top-benthic predators on sandy beaches in the sub-tropical and tropical regions around the world. They are omnivores and opportunistic feeders with varied feeding modes, such that they can exert cascading trophic effects on intertidal communities. Although there is a wealth of literature on the diet of ghost crabs based on qualitative reports of direct observation of predation, tracks/signs of feeding activities, or presence/absence data of prey items in foregut content analyses, there is hardly any quantitative analyses of food resources in the field that are available to these top predators on the sandy shore. While the abundance of immobile food resources can be ascertained by sediment sample assays, specialized sampling methods have been used for the collection and enumeration of mobile prey items. There is a need also to understand the period of foraging activity of the study species in order to track the predator-prey interaction at the appropriate time of the day. We outline three techniques suitable for the collection of prey types with different distribution, activity period and mobility: 1) surface-dwelling prey, 2) prey that burrow, and 3) prey that are capable of flying, a novel method that has not been utilized and described before.


2016 ◽  
Vol 75 (s1) ◽  
Author(s):  
Kenneth W. Cummins

<p>Over the last fifty years, research on freshwater macroinvertebrates has been driven largely by the state of the taxonomy of these animals. In the great majority of studies conducted during the 2000s macroinvertebrates have been operationally defined by investigators as invertebrates retained by a 250 μ mesh in field sampling devices. Significant advances have been and continue to be made in developing ever more refined keys to macroinvertebrate groups. The analysis by function is a viable alternative when advances in macroinvertebrate ecological research is restricted by the level of detail in identifications. Focus on function, namely adaptations of macroinvertebrates to habitats and the utilization of food resources, has facilitated ecological evaluation of freshwater ecosystems (Functional feeding groups; FFG). As the great stream ecologist Noel Hynes observed, aquatic insects around the world exhibit similar morphologies and behaviors, even though they are in very different taxonomic groups. This is the basis for the FFG analysis that was initially developed in the early 1970s. FFG analysis applies taxonomy only to the level of detail that allows assignment to one of six FFG categories: scrapers adapted to feed on periphyton, detrital shredders adapted to feed on coarse (CPOM) riparian-derived plant litter that has been colonized by microbes, herbivore shredders that feed on live, rooted aquatic vascular plants, filtering collectors adapted to remove fine particle detritus (FPOM) from the water column, gathering collectors adapted to feed on FPOM where it is deposited on surfaces or in crevices in the sediments, and predators that capture live prey. The interacting roles of these FFGs in stream ecosystems were originally depicted in a conceptual model. Thus, there are a limited number of adaptations exhibited by stream macroinvertebrates that exploit these habitats and food resources. This accounts for the wide range of macroinvertebrate taxa in freshwater ecosystems found in different geographical settings that are represented by a much smaller number of FFGs. An example of the generality of the functional group concept is the presence of detrital shredders that are dependent upon riparian plant litter inputs being found in essentially all forested streams world-wide (<em>e.g</em>., across the USA and Canada, Chile, Brazil, West Africa, New Zealand, Australia, Japan, Thailand; Cummins, <em>unpublished</em>). Freshwater macroinvertebrate taxonomic determinations, especially at the species level, may be the best basis for developing specific indices of pollution (tolerance values in ecological tables). However, the FFG method appears to provide better indicators of overall freshwater ecosystem condition.</p>


2011 ◽  
Vol 13 (3) ◽  
pp. 203-218 ◽  
Author(s):  
SK Hooker ◽  
A Cañadas ◽  
KD Hyrenbach ◽  
C Corrigan ◽  
JJ Polovina ◽  
...  
Keyword(s):  

2020 ◽  
Vol 4 (1) ◽  
Author(s):  
Catherine M. Febria ◽  
Maggie Bayfield ◽  
Kathryn E. Collins ◽  
Hayley S. Devlin ◽  
Brandon C. Goeller ◽  
...  

In Aotearoa New Zealand, agricultural land-use intensification and decline in freshwater ecosystem integrity pose complex challenges for science and society. Despite riparian management programmes across the country, there is frustration over a lack in widespread uptake, upfront financial costs, possible loss in income, obstructive legislation and delays in ecological recovery. Thus, social, economic and institutional barriers exist when implementing and assessing agricultural freshwater restoration. Partnerships are essential to overcome such barriers by identifying and promoting co-benefits that result in amplifying individual efforts among stakeholder groups into coordinated, large-scale change. Here, we describe how initial progress by a sole farming family at the Silverstream in the Canterbury region, South Island, New Zealand, was used as a catalyst for change by the Canterbury Waterway Rehabilitation Experiment, a university-led restoration research project. Partners included farmers, researchers, government, industry, treaty partners (Indigenous rights-holders) and practitioners. Local capacity and capability was strengthened with practitioner groups, schools and the wider community. With partnerships in place, co-benefits included lowered costs involved with large-scale actions (e.g., earth moving), reduced pressure on individual farmers to undertake large-scale change (e.g., increased participation and engagement), while also legitimising the social contracts for farmers, scientists, government and industry to engage in farming and freshwater management. We describe contributions and benefits generated from the project and describe iterative actions that together built trust, leveraged and aligned opportunities. These actions were scaled from a single farm to multiple catchments nationally.


2007 ◽  
Author(s):  
Sean D. Farley ◽  
Herman Griese ◽  
Rick Sinnott ◽  
Jessica Coltrane ◽  
Chris Garner ◽  
...  

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