Ceasefire: minimal aggression among Murray River crayfish feeding upon patches of allochthonous material

2015 ◽  
Vol 63 (2) ◽  
pp. 115 ◽  
Author(s):  
Danswell Starrs ◽  
Brendan C. Ebner ◽  
Christopher J. Fulton
Keyword(s):  
Leaf Litter ◽  
Aquatic Ecosystems ◽  
Plant Material ◽  
Woody Debris ◽  
Small Scale ◽  
Freshwater Crayfish ◽  
Fine Woody Debris ◽  
Trophic Pathways ◽  
Murray River ◽  
Freshwater Invertebrate

Transport and processing of allochthonous material is crucial for trophic pathways in headwater streams. Freshwater crayfish are known to affect and exploit the break-down of in-stream terrestrial plant material into detritus. We recorded Euastacus armatus (Murray River crayfish) individuals feeding on discrete patches of allochthonous material within an unregulated section of the Goodradigbee River, an upland stream in temperate Australia. Despite suggestions of aggressive territoriality, E. armatus were observed by remote and manual underwater filming to feed in non-aggressive aggregations on these piles of fine woody debris and leaf litter. On the basis of observations of 25 individuals found in the vicinity of the allochthonous patches, this population comprised mostly female individuals at smaller sizes of maturity than has been recorded for lowland populations of E. armatus. Our study confirms the importance of concentrated allochthonous food patches for detritivores, and points to the important trophic linkage between terrestrial and aquatic ecosystems via a widespread and iconic freshwater invertebrate. Moreover, these non-aggressive feeding aggregations of E. armatus challenge notions of aggression in this species that have been developed in small-scale aquarium studies.

scholarly journals How to Evaluate Downed Fine Woody Debris Including Logging Residues?

Forests ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 881
Author(s):  
Nathalie Korboulewsky ◽  
Isabelle Bilger ◽  
Abdelwahab Bessaad
Keyword(s):  
Wood Density ◽  
Stock Assessment ◽  
Woody Debris ◽  
Diameter Class ◽  
Density Measurements ◽  
Fine Woody Debris ◽  
Forest Inventories ◽  
Test Zone ◽  
Fixed Area ◽  
Volume Estimates

Volume or biomass estimates of downed woody debris are crucial for numerous applications such as forest carbon stock assessment, biodiversity assessments, and more recently for environmental evaluations of biofuel harvesting practices. Both fixed-area sampling (FAS) and line-intersect sampling (LIS) are used in forest inventories and ecological studies because they are unbiased and accurate methods. Nevertheless, most studies and inventories take into account only coarse woody debris (CWD, >10 cm in diameter), although fine woody debris (FWD) can account for a large part of the total downed biomass. We compared the LIS and FAS methods for FWD volume or biomass estimates and evaluated the influence of diameter and wood density measurements, plot number and size. We used a Test Zone (a defined surface area where a complete inventory was carried out, in addition to FAS and LIS), a Pilot Stand (a forest stand where both LIS and FAS methods were applied) and results from 10 field inventories in deciduous temperate forest stands with various conditions and amounts of FWD. Both methods, FAS and LIS, provided accurate (in trueness and precision) volume estimates, but LIS proved to be the more efficient. Diameter measurement was the main source of error: using the mean diameter, even by diameter class, led to an error for volume estimates of around 35%. On the contrary, wood density measurements can be simplified without much influence on the accuracy of biomass estimates (use of mean density by diameter class). We show that the length and number of transects greatly influences the estimates, and that it is better to apply more, shorter transects than fewer, longer ones. Finally, we determined the optimal methodology and propose a simplification of some measurements to obtain the best time-precision trade-off for FWD inventories at the stand level.

Impact of recent artisanal small-scale gold mining in Senegal: Mercury and methylmercury contamination of terrestrial and aquatic ecosystems

2019 ◽  
Vol 669 ◽  
pp. 185-193 ◽  
Author(s):  
Birane Niane ◽  
Stéphane Guédron ◽  
Frédéric Feder ◽  
Samuel Legros ◽  
Papa Malick Ngom ◽  
...  
Keyword(s):  
Aquatic Ecosystems ◽  
Gold Mining ◽  
Small Scale

The Beetle Community of Small Oak Twigs in Louisiana, with a Literature Review of Coleoptera from Fine Woody Debris

2009 ◽  
Vol 63 (3) ◽  
pp. 239-263 ◽  
Author(s):  
Michael L. Ferro ◽  
Matthew L. Gimmel ◽  
Kyle E. Harms ◽  
Christopher E. Carlton
Keyword(s):  
Literature Review ◽  
Woody Debris ◽  
Fine Woody Debris

scholarly journals The Influence of Prescribed Fire, Habitat, and Weather on Amblyomma americanum (Ixodida: Ixodidae) in West-Central Illinois, USA

Insects ◽  
2018 ◽  
Vol 9 (2) ◽  
pp. 36 ◽  
Author(s):  
Mary Gilliam ◽  
Will Rechkemmer ◽  
Kenneth McCravy ◽  
Seán Jenkins
Keyword(s):  
Leaf Litter ◽  
Negative Correlation ◽  
Coarse Woody Debris ◽  
Woody Debris ◽  
Life Stage ◽  
Amblyomma Americanum ◽  
Sample Period ◽  
Bare Ground ◽  
Tick Abundance ◽  
Weak Negative Correlation

The distribution of Amblyomma americanum (L.) is changing and reports of tick-borne disease transmitted by A. americanum are increasing in the USA. We used flagging to collect ticks, surveyed vegetation and collected weather data in 2015 and 2016. A. americanum dominated collections in both years (97%). Ticks did not differ among burn treatments; however, tick abundance differed between years among total, adult, and larval ticks. Habitat variables showed a weak negative correlation to total ticks in respect to: Shannon diversity index, percent bare ground, perennial cover, and coarse woody debris. Nymphal ticks showed a weak negative correlation to percent bare ground and fewer adults were collected in areas with more leaf litter and coarse woody debris. Conversely, we found larvae more often in areas with more total cover, biennials, vines, shrubs, and leaf litter, suggesting habitat is important for this life stage. We compared weather variables to tick presence and found, in 2015, temperature, precipitation, humidity, and sample period influenced tick collection and were life stage specific. In 2016, temperature, precipitation, humidity, wind, and sample period influenced tick collection and were also life stage specific. These results indicate that spring burns in an oak woodland do not reduce ticks; other variables such as habitat and weather are more influential on tick abundance or presence at different life stages.

Time for 3D: UAV-based lidar for modelling splash erosion under vegetation

2021 ◽  
Author(s):  
Johannes Antenor Senn ◽  
Steffen Seitz ◽  
Fabian Ewald Fassnacht ◽  
Zahra Hosseini ◽  
Jannika Schäfer
Keyword(s):  
Kinetic Energy ◽  
Leaf Litter ◽  
Vegetation Structure ◽  
Plant Traits ◽  
3D Structure ◽  
Protective Layer ◽  
Point Clouds ◽  
Small Scale ◽  
Initial Results ◽  
Covering Vegetation

<p>Rain throughfall under vegetation is determined by characteristics of the vertical structure and the associated plant traits. It goes both ways: A protective layer of ground covering vegetation or leaf litter can decrease throughfall kinetic energy (TKE), whereas the formation of large drips in the canopy layers has been found to increase TKE. Abstracting the three-dimensional vegetation structure into usable quantitative metrics is challenging, and therefore these processes have not yet been sufficiently integrated into spatial erosion models. The vegetation splash factor (VSF) was designed to close this gap (Senn et al. 2020, DOI: 10.1002/esp.4820). The VSF quantifies the influence of vegetation on TKE and can be calculated from aerial lidar point clouds. In the first step, we derive the vegetation cover in a voxel space, which then allows modelling the proportional contribution of drips per layer to reach the ground. Hence, the approach is strictly based on the 3D structure rather than conventional forestry parameters, e.g. crown diameter or leaf sizes. Here, we present the result of the first application of the VSF in a small scale field study using splash cup measurements to validate and refine the concept.</p><p>We implemented the experiment in a mixed-broadleaf forest near Bretten, Germany with a beech and an oak-dominated plot to cover a variety of vertical forest structure configurations and a diverse composition of species. Each plot comprised two transects of ten splash cups to measure sand loss - as a proxy for TKE - during six individual rainfall events. In addition, we used micro-scale runoff plots to determine the effect of soil covering layers such as leaf litter or biological soil crusts in comparison to bare soil. The VSF was calculated in R with a voxel resolution of 0.5 x 0.5 x 0.25 m using a UAV lidar dataset. </p><p>Initial results from the splash cup measurements showed that young oak induced about 70 % higher TKE than adult beech trees. Among the individual cup positions, the lowest energy values were measured without canopy influence as freefall kinetic energy (FKE), TKE at positions with an intermediate young growth and shrub layer showed medium values. In near-trunk and mid-positions without intermediate layers, we measured TKE values more than twice as high as FKE. This resulted in significant sediment removal beneath the tree layer when the ground covering vegetation layer was removed, which is in accordance with studies from other ecosystems. Grouped according to these conventional vegetation structural criteria, we found that the calculated VSF values clustered around similar values and correlated with sand loss from splash cups. From these initial results, we assume general suitability of the VSF to reflect the influence of vegetation structure on TKE. Further, more detailed analysis will now be done to adjust and calibrate the VSF model to produce more indicative results. The preliminary findings presented here will be further expanded to be presented at vEGU21.</p>

scholarly journals Gammarus-Microbial Interactions: A Review

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Daniel Nelson
Keyword(s):  
Leaf Litter ◽  
Aquatic Ecosystems ◽  
Poor Quality ◽  
Fungal Species ◽  
Microbial Interactions ◽  
Negative Effects ◽  
Freshwater Habitats ◽  
In The Wild ◽  
Survival And Growth ◽  
Organic Matter Fractions

Gammarusspp. are typically classified as shredders under the functional feeding group classification. In the wild and in the laboratory,Gammarusspp. will often shred leaves, breaking them down into finer organic matter fractions. However, leaf litter is a poor quality food source (i.e., high C : N and C : P ratios) and very little leaf material is assimilated by shredders. In freshwater habitats leaf litter is colonized rapidly (within ∼1-2 weeks) by aquatic fungi and bacteria, making the leaves more palatable and nutritious to consumers. Several studies have shown thatGammarusspp. show preference for conditioned leaves over nonconditioned leaves and certain fungal species to others. Furthermore,Gammarusspp. show increased survival and growth rates when fed conditioned leaves compared to non-conditioned leaves. Thus,Gammarusspp. appear to rely on the microbial biofilm associated with leaf detritus as a source of carbon and/or essential nutrients. Also,Gammarusspp. can have both positive and negative effects on the microbial communities on which they fed, making them an important component of the microbial loop in aquatic ecosystems.

Sign in / Sign up

Export Citation Format

Share Document