Benthic invertebrate recolonization of small-scale disturbances in the littoral zone of a subtropical Florida lake

Hydrobiologia ◽  
1984 ◽  
Vol 109 (3) ◽  
pp. 193-205 ◽  
Author(s):  
Bruce C. Cowell
Keyword(s):  
Littoral Zone ◽  
Benthic Invertebrate ◽  
Small Scale

Rates of Food Exploitation by Littoral Fishes in a Mesotrophic North-Temperate Lake

1985 ◽  
Vol 42 (3) ◽  
pp. 556-566 ◽  
Author(s):  
D. Boisclair ◽  
W. C. Leggett
Keyword(s):  
Littoral Zone ◽  
Geometric Mean ◽  
Dry Weight ◽  
Benthic Invertebrate ◽  
Trophic Levels ◽  
Total Biomass ◽  
Temperate Lakes ◽  
Total Food ◽  
North Temperate Lakes ◽  
Food Consumed

The relationship between the biomass of food consumed by the littoral zone fish community of Lake Memphremagog, Quebec, and the total biomass of littoral zone food present was estimated on a daily and annual basis. The dominant food consumed were benthic invertebrates followed by forage fishes and plankton. The daily geometric mean exploitation rate was 0.55% of the total dry weight food biomass in the littoral zone. The corresponding annual rate was 72%. Energy equivalents were 0.81% (daily) and 105% (annual). When benthic invertebrate biomass values were adjusted to more accurately reflect availability (on the basis of depth distribution in the sediments and size) the geometric mean dry weight exploitation rates were 0.80% (daily) and 104% (annual). Corresponding energy rates were 1.15% (daily) and 150% (annual). These rates are significantly lower than reported benthic P/B ratios for 21 north-temperate lakes. These data indicate that littoral zone fishes crop only a very small fraction of the food biomass in the littoral zone. We conclude that the behaviors of both predator and prey act to limit the available fraction of the total food biomass and predict that the ratio of available to total food biomass in the littoral zone of north-temperate lakes will approximate 1%. This is consistent with existing empirical models linking fish production/biomass with biomass at lower trophic levels.

scholarly journals Investigating invertebrate biodiversity around large wood: taxonomic vs functional metrics

2020 ◽  
Vol 82 (4) ◽  
Author(s):  
Chiara Magliozzi ◽  
Albin Meyer ◽  
Philippe Usseglio-Polatera ◽  
Anne Robertson ◽  
Robert C. Grabowski
Keyword(s):  
Management Strategies ◽  
Taxonomic Diversity ◽  
Benthic Invertebrate ◽  
Small Scale ◽  
Large Wood ◽  
Effective Management ◽  
River Channels ◽  
Invertebrate Biodiversity ◽  
Ecological Implications ◽  
Structural Responses

Abstract Large wood is a key component of river channels that affects numerous hydrological, physical and geomorphological processes. It promotes a diversity of benthic habitats in-channel and has shown to support more abundant and diverse benthic macroinvertebrate assemblages in previous ecological studies. However, the effects of large wood on the structural and functional diversities of hyporheic invertebrates are less well studied, and simultaneous examination of these diversity metrics on hyporheic and benthic compartments of the stream bed has not been conducted previously. Therefore, this study investigates the taxonomic and functional diversities of hyporheic and benthic invertebrate assemblages around natural accumulations of large wood in a British lowland river. Taxonomic and functional diversities were partitioned (into alpha, beta, and gamma diversities) and examined in reaches with and without large wood (control). We found that functional diversity is often decoupled from taxonomic diversity, demonstrating a functional redundancy of the macroinvertebrate assemblage for both hyporheic and benthic zones. Moreover, the highest functional variability at alpha-scale was observed in large wood habitats, which suggests that taxonomic diversity is enhanced by the small-scale environmental heterogeneity around large wood. To this end, this study contributes empirical evidence of functional and structural responses of invertebrates to large wood accumulation. Such information could be used to better understand the ecological implications of restoration works in lowland rivers and guide more effective management strategies.

scholarly journals Benthic grazing in a eutrophic river: cascading effects of zoobenthivorous fish mask direct effects of herbivorous fish

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4381 ◽  
Author(s):  
Madlen Gerke ◽  
Daniel Cob Chaves ◽  
Marc Richter ◽  
Daniela Mewes ◽  
Jörg Schneider ◽  
...  
Keyword(s):  
Dry Mass ◽  
Benthic Invertebrate ◽  
Herbivorous Fish ◽  
Small Scale ◽  
Direct Effects ◽  
Cascading Effects ◽  
Periphyton Biomass ◽  
Fish Grazing ◽  
The Impact ◽  
Eutrophic River

Benthic grazing strongly controls periphyton biomass. The question therefore arises whether benthic grazing could be used as a tool to reduce excessive growth of periphyton in nutrient-enriched rivers. Although benthic invertebrate grazers reduce the growth of periphyton, this is highly context dependent. Here we assessed whether the only obligate herbivorous fish in European rivers, the common nase (Chondrostoma nasus L.), is able to reduce periphyton biomass in a eutrophic river. We conducted three consecutive in situ experiments at low, intermediate and high densities of nase in the river using standard tiles on the river bottom naturally covered with periphyton that were accessible to fish and tiles that excluded fish foraging with electric exclosures. The biomass of benthic invertebrate grazers was very low relative to nase. We hypothesised that nase would reduce periphyton biomass on accessible tiles and therefore expected higher periphyton biomass on the exclosure tiles, at least at intermediate and high densities of nase in the river. Contrary to our expectation, the impact of fish grazing was low even at high fish density, as judged by the significantly lower chlorophyll a concentration on exclosure tiles even though the ash-free dry mass on accessible and exclosure tiles did not differ. The lower chlorophyll a concentrations on exclosure tiles might be explained by a higher biomass of invertebrate grazers on the exclosure tiles, which would indicate that the effect of invertebrate grazers was stronger than that of herbivorous fish grazers. The high biomass of invertebrate grazers on exclosure tiles likely arose from the exclusion of zoobenthivorous fish, which occur in the river at high densities. The results of our small-scale experiments suggested that cascading top-down effects of zoobenthivorous fish have a higher impact on periphyton biomass than direct effects of herbivorous nase.

scholarly journals Direct and indirect responses of a freshwater food web to a potent synthetic oestrogen

2014 ◽  
Vol 369 (1656) ◽  
pp. 20130578 ◽  
Author(s):  
Karen A. Kidd ◽  
Michael J. Paterson ◽  
Michael D. Rennie ◽  
Cheryl L. Podemski ◽  
Dave L. Findlay ◽  
...  
Keyword(s):  
Indirect Effects ◽  
Fathead Minnow ◽  
Lake Trout ◽  
Prey Availability ◽  
Pimephales Promelas ◽  
Endocrine Disrupting Chemicals ◽  
Benthic Invertebrate ◽  
Small Scale ◽  
Direct Effects ◽  
Experimental Lakes Area

Endocrine-disrupting chemicals (EDCs) in municipal effluents directly affect the sexual development and reproductive success of fishes, but indirect effects on invertebrate prey or fish predators through reduced predation or prey availability, respectively, are unknown. At the Experimental Lakes Area in northwestern Ontario, Canada, a long-term, whole-lake experiment was conducted using a before-after-control-impact design to determine both direct and indirect effects of the synthetic oestrogen used in the birth control pill, 17α-ethynyloestradiol (EE2). Algal, microbial, zooplankton and benthic invertebrate communities showed no declines in abundance during three summers of EE2 additions (5–6 ng l −1 ), indicating no direct toxic effects. Recruitment of fathead minnow ( Pimephales promelas ) failed, leading to a near-extirpation of this species both 2 years during (young-of-year, YOY) and 2 years following (adults and YOY) EE2 additions. Body condition of male lake trout ( Salvelinus namaycush ) and male and female white sucker ( Catostomus commersonii ) declined before changes in prey abundance, suggesting direct effects of EE2 on this endpoint. Evidence of indirect effects of EE2 was also observed. Increases in zooplankton, Chaoborus , and emerging insects were observed after 2 or 3 years of EE2 additions, strongly suggesting indirect effects mediated through the reduced abundance of several small-bodied fishes. Biomass of top predator lake trout declined by 23–42% during and after EE2 additions, most probably an indirect effect from the loss of its prey species, the fathead minnow and slimy sculpin ( Cottus cognatus ). Our results demonstrate that small-scale studies focusing solely on direct effects are likely to underestimate the true environmental impacts of oestrogens in municipal wastewaters and provide further evidence of the value of whole-ecosystem experiments for understanding indirect effects of EDCs and other aquatic stressors.

scholarly journals Environmental Geophysical Study of the Groundwater Mineralization in a Plot of the Cotonou Littoral Zone (South Benin)

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Yalo Nicaise ◽  
Descloitres Marc ◽  
Alassane Abdoukarim ◽  
Mama Daouda ◽  
Boukari Moussa
Keyword(s):  
Fresh Water ◽  
Water Table ◽  
Littoral Zone ◽  
Geophysical Methods ◽  
Environmental Study ◽  
Small Scale ◽  
Water Interface ◽  
Water Conductivity ◽  
Electrical Resistivities ◽  
Geophysical Study

Geophysical investigations comprising electrical resistivity and electromagnetic conductivities methods were deployed in a 350 m2sector, strewn with 11 wells. Within the framework of an environmental study on a small scale in the south of Benin, the water conductivity of these wells was measured to determine in a direct way mineralization of the coastal water table in the littoral zone. This environmental study aimed to prospect by the geophysical methods the space extension of the water table mineralization obtained by direct measurements of water conductivity in the well and the depth of the fresh water/salted water interface in the coastal aquifer. Electromagnetic measurements of conductivities made it possible to chart a gradient of mineralization in the northwest direction. The logs of vertical electric soundings showed a deepening of the fresh water/salted water interface in the southern part and its rupture in the northern part. The electrical resistivities of the interface are sensitive to the degree of its mineralization. It has been observed that the geophysical methods in electrical and electromagnetic prospection are a great contribution to the environmental study of the water table mineralization in the littoral zone for a sustainable management of the water resource.

Reasons to strike first

2019 ◽  
Vol 42 ◽  
Author(s):  
William Buckner ◽  
Luke Glowacki
Keyword(s):  
Intergroup Conflict ◽  
Small Scale

Abstract De Dreu and Gross predict that attackers will have more difficulty winning conflicts than defenders. As their analysis is presumed to capture the dynamics of decentralized conflict, we consider how their framework compares with ethnographic evidence from small-scale societies, as well as chimpanzee patterns of intergroup conflict. In these contexts, attackers have significantly more success in conflict than predicted by De Dreu and Gross's model. We discuss the possible reasons for this disparity.

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