scholarly journals Larval fish in troubled waters — is the behavioural response of larval fish to hydrodynamic impacts active or passive?

2012 ◽  
Vol 69 (10) ◽  
pp. 1576-1584 ◽  
Author(s):  
Stefan Stoll ◽  
Peter Beeck
Keyword(s):  
Larval Fish ◽  
Fish Larvae ◽  
Activity Patterns ◽  
Behavioural Response ◽  
Activity Level ◽  
Microhabitat Use ◽  
Wave Regime ◽  
Allis Shad ◽  
Alosa Alosa ◽  
Spatio Temporal

In a mesocosm experiment, we tested whether larval fish show an active behavioural response to hydrodynamic impacts. Exposing 1- to 3-week-old allis shad ( Alosa alosa ) larvae to a pulsed wave regime, we found that already 1-week-old larvae immediately adapt their microhabitat use and activity patterns at the onset of the wave pulses. The fish larvae instantaneously increased their activity level and moved downwards, concentrating in the calmer lower third of the water column. Within 4 min after the end of the wave pulse, the fish returned to their former distribution. Two- and 3-week-old fish larvae foraged close to the bottom substratum during calm periods but avoided this zone during the wave pulses. Thus, larval fish show an active response to hydrodynamic impacts. With the ability to adjust microhabitat use and activity level, already fish larvae are able to trade costs and benefits associated with spatio-temporal hydrodynamic heterogeneity. In particular, fish larvae should be able to minimize some of the harmful effects of navigation-induced waves where calmer evasion habitats are available.

scholarly journals Spatio-temporal distribution of fish larvae in relation to ontogeny and water quality in the oligohaline zone of a North Brazilian estuary

2013 ◽  
Vol 13 (3) ◽  
pp. 55-63 ◽  
Author(s):  
Valérie Sarpedonti ◽  
Érica Moema Silva da Anunciação ◽  
Adriana Oliveira Bordalo
Keyword(s):  
Larval Fish ◽  
Fish Larvae ◽  
Temporal Distribution ◽  
Capital City ◽  
Rainy Period ◽  
Larval Distribution ◽  
Spatio Temporal ◽  
The City ◽  
Urban Activity ◽  
Distribution Of Fish

Larval fish assemblage in Guajará Bay was studied through four quarterly field campaigns and discussed in relation to individuals' development stages and exposure to contaminants poured out by the Pará State Capital City, Belém. Larval densities were low and diversity extremely poor with a strong dominance of clupeids, engraulids and, to a lower extent, sciaenids. The main spawning season was registered at the onset of the rainy period. Pre-flexion and flexion clupeiforms remained in the farmost stations from the city while post-flexion larvae were found near urban activity centres. Unlikely, pre-flexion and flexion sciaenids were scattered along the city waterfront. Post-flexion larvae were rare; it is suggested that sciaenids use the bay as a transitory route between their spawning grounds and more distant nursery grounds. The waters around the city of Belém showed signs of contamination. However, based on the literature, Guajará Bay environmental quality at the time of the study was suitable for fish larvae life. Nitrate with pH best explained larval distribution.

scholarly journals Spatio-temporal variations in abundance and assemblage patterns of fish larvae and their relationships to environmental variables in Sirindhron Reservoir of the Lower Mekong Basin, Thailand

2016 ◽  
Vol 63 (3) ◽  
Author(s):  
Tuantong Jutagate ◽  
Achara Rattanachai ◽  
Suriya Udduang ◽  
Sithan Lek-Ang ◽  
Sovan Lek
Keyword(s):  
Species Richness ◽  
Temporal Dynamics ◽  
Larval Fish ◽  
Fish Larvae ◽  
Abundant Species ◽  
Temporal Variations ◽  
Larval Abundance ◽  
Wet Season ◽  
North East ◽  
Spatio Temporal

The spatio-temporal dynamics of fish larvae in Sirindhron Reservoir, north-east Thailand, were investigated from February 2008 to January 2009. The five most abundant species accounted for 53.6% of the total catch and comprised Clupeicthys aesarnensis, Rasbora borapetensis, Barbonymus gonionotus, Esomus metallicus and Oreochromis niloticus. Total larval abundance and species richness varied among sampling months but did not vary with zones in the reservoir. The abundance and species richness of fish larvae showed correlation with flooding, vegetation cover, water level, water temperature and turbidity. A self-organising map (SOM) was used to represent the larval fish assemblage patterns and three assemblage patterns were clearly distinguished primarily according to seasons. In conclusion, the fish larval abundance was greatest during the wet season and the most diverse assemblages were found in the zones adjacent to the connected river upstream during the wet season.

scholarly journals Application of YOLOv4 for Detection and Motion Monitoring of Red Foxes

Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1723
Author(s):  
Anne K. Schütz ◽  
Verena Schöler  ◽  
E. Tobias Krause  ◽  
Mareike Fischer  ◽  
Thomas Müller  ◽  
...  
Keyword(s):  
Animal Welfare ◽  
Early Recognition ◽  
Activity Patterns ◽  
Automatic Detection ◽  
Animal Husbandry ◽  
Video Data ◽  
Activity Level ◽  
Red Foxes ◽  
Experimental Conditions ◽  
Animal Activity

Animal activity is an indicator for its welfare and manual observation is time and cost intensive. To this end, automatic detection and monitoring of live captive animals is of major importance for assessing animal activity, and, thereby, allowing for early recognition of changes indicative for diseases and animal welfare issues. We demonstrate that machine learning methods can provide a gap-less monitoring of red foxes in an experimental lab-setting, including a classification into activity patterns. Therefore, bounding boxes are used to measure fox movements, and, thus, the activity level of the animals. We use computer vision, being a non-invasive method for the automatic monitoring of foxes. More specifically, we train the existing algorithm ‘you only look once’ version 4 (YOLOv4) to detect foxes, and the trained classifier is applied to video data of an experiment involving foxes. As we show, computer evaluation outperforms other evaluation methods. Application of automatic detection of foxes can be used for detecting different movement patterns. These, in turn, can be used for animal behavioral analysis and, thus, animal welfare monitoring. Once established for a specific animal species, such systems could be used for animal monitoring in real-time under experimental conditions, or other areas of animal husbandry.

First evidence of natural reproduction of the Allis shad Alosa alosa in the River Rhine following re-introduction measures

2015 ◽  
Vol 87 (2) ◽  
pp. 487-493 ◽  
Author(s):  
M. Hundt ◽  
A. Scharbert ◽  
U. Weibel ◽  
G. Kuhn ◽  
K. Metzner ◽  
...  
Keyword(s):  
River Rhine ◽  
Allis Shad ◽  
Alosa Alosa ◽  
Natural Reproduction

scholarly journals Fish larvae exploit edge vortices along their dorsal and ventral fin folds to propel themselves

2016 ◽  
Vol 13 (116) ◽  
pp. 20160068 ◽  
Author(s):  
Gen Li ◽  
Ulrike K. Müller ◽  
Johan L. van Leeuwen ◽  
Hao Liu
Keyword(s):  
Larval Fish ◽  
Fish Larvae ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Bony Fish ◽  
The Body ◽  
Functional Explanation ◽  
Image Velocimetry ◽  
Median Fins

Larvae of bony fish swim in the intermediate Reynolds number ( Re ) regime, using body- and caudal-fin undulation to propel themselves. They share a median fin fold that transforms into separate median fins as they grow into juveniles. The fin fold was suggested to be an adaption for locomotion in the intermediate Reynolds regime, but its fluid-dynamic role is still enigmatic. Using three-dimensional fluid-dynamic computations, we quantified the swimming trajectory from body-shape changes during cyclic swimming of larval fish. We predicted unsteady vortices around the upper and lower edges of the fin fold, and identified similar vortices around real larvae with particle image velocimetry. We show that thrust contributions on the body peak adjacent to the upper and lower edges of the fin fold where large left–right pressure differences occur in concert with the periodical generation and shedding of edge vortices. The fin fold enhances effective flow separation and drag-based thrust. Along the body, net thrust is generated in multiple zones posterior to the centre of mass. Counterfactual simulations exploring the effect of having a fin fold across a range of Reynolds numbers show that the fin fold helps larvae achieve high swimming speeds, yet requires high power. We conclude that propulsion in larval fish partly relies on unsteady high-intensity vortices along the upper and lower edges of the fin fold, providing a functional explanation for the omnipresence of the fin fold in bony-fish larvae.

Pedestrian Activity Among California Adults

2009 ◽  
Vol 6 (1) ◽  
pp. 15-23 ◽  
Author(s):  
Anna E. Mathews ◽  
Natalie Colabianchi ◽  
Brent Hutto ◽  
Delores M. Pluto ◽  
Steve P. Hooker
Keyword(s):  
Physical Activity ◽  
Older Adults ◽  
Activity Patterns ◽  
Physical Activity Promotion ◽  
Activity Level ◽  
Activity Levels ◽  
Public Health Agencies ◽  
Activity Promotion ◽  
Health Agencies ◽  
Random Digit Dial

Background:The objectives of this study were to assess (1) pedestrian activity levels among adults, (2) where and why adults engage in pedestrian activity, and (3) what adults consider when deciding where to engage in pedestrian activity.Methods:Pedestrian activity was assessed in 12,036 California adults, ≥18 years, using a random digit-dial telephone survey.Results:Significant differences were identified by race, sex, age, and physical activity level in the type, location, and purpose of pedestrian activities. Men engage in pedestrian activity at work, and women engage in pedestrian activity while escorting children to school and running errands. Whites primarily engage in leisure-time pedestrian activity, and non-whites are more likely to engage in pedestrian activity for transportation. Older adults were less active than their younger counterparts.Conclusions:These findings should be considered by public health agencies and their partners as they continue to increase and promote opportunities for pedestrian activity. Additional research is needed to assess older adults’ physical activity patterns and preferences, barriers, and facilitators to effectively tailor physical activity promotion efforts to this at-risk group.

scholarly journals Osmotic induction improves batch marking of larval fish otoliths with enriched stable isotopes

2014 ◽  
Vol 71 (9) ◽  
pp. 2530-2538 ◽  
Author(s):  
Emmanuel de Braux ◽  
Fletcher Warren-Myers ◽  
Tim Dempster ◽  
Per Gunnar Fjelldal ◽  
Tom Hansen ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Salmo Salar ◽  
Larval Fish ◽  
Fish Larvae ◽  
Cost Effective ◽  
Industrial Applications ◽  
Chemical Markers ◽  
Potential Applications ◽  
Recent Method ◽  
Batch Marking

Abstract Otolith marking with enriched stable isotopes via immersion is a recent method of batch marking larval fish for a range of research and industrial applications. However, current immersion times and isotope concentrations required to successfully mark an otolith limit the utility of this technique. Osmotic induction improves incorporation and reduces immersion time for some chemical markers, but its effects on isotope incorporation into otoliths are unknown. Here, we tested the effects of osmotic induction over a range of different isotope concentrations and immersion times on relative mark success and strength for 26Mg:24Mg, 86Sr:88Sr and 137Ba:138Ba on Atlantic salmon (Salmo salar) larvae. 71% and 100% mark success were achieved after 1 h of immersion for 86Sr (75 µg L−1) and 137Ba (30 µg L−1) isotopes, respectively. Compared with conventional immersion, osmotic induction improved overall mark strength for 86Sr and 137Ba isotopes by 26–116%, although this effect was only observed after 12 h of immersion and predominately for 86Sr. The results demonstrate that osmotic induction reduces immersion times and the concentrations of isotope required to achieve successful marks. Osmotically induced isotope labels via larval immersion may prove a rapid and cost-effective way of batch marking fish larvae across a range of potential applications.

scholarly journals Feeding of the Brycon cephalus, Triportheus elongatus and Semaprochilodus insignis (osteichthyes, characiformes) larvae in Solimões/Amazonas River and floodplain areas.

2002 ◽  
Vol 32 (3) ◽  
pp. 499-499 ◽  
Author(s):  
Rosseval Galdino LEITE ◽  
Carlos A.R.M. ARAUJO-LIMA
Keyword(s):  
Food Item ◽  
Prey Size ◽  
Larval Fish ◽  
Fish Larvae ◽  
Trophic Relations ◽  
Fish Feeding ◽  
Important Species ◽  
Flooded Forests ◽  
Commercially Important

Information on larval fish feeding is essential for understanding their trophic relations, including the management in conditions totally or partially controlled by humans. An experiment was designed to evaluate the larval diets of three commercially important species. Four varzea-lakes and the adjacent river were sampled with bongo and hand nets from January 1993 to November 1995. Larval diets were evaluated by length-classes and capture sites, and were tested by two factor ANOVA. The larvae were feeding in all habitats, except in the flooded forests. The three species had different diets, which varied with their length and lake. The rotifers were the main initial food item of the three species, replaced by fish larvae in Brycon cephalus, cladocerans in Triportheus elongatus and detritus in Semaprochilodus insignis. The increase of the ingestion limit, as the larvae grew, was higher than the increase in the consumed prey size for the three species.

scholarly journals Fishers’ knowledge on historical changes and conservation of Allis shad -Alosa alosa (Linnaeus, 1758) in Minho River, Iberian Peninsula

2021 ◽  
pp. 102094
Author(s):  
Heitor O. Braga ◽  
Mariana G. Bender ◽  
Henrique M.F. Oliveira ◽  
Mário J. Pereira ◽  
Ulisses M. Azeiteiro
Keyword(s):  
Iberian Peninsula ◽  
Historical Changes ◽  
Allis Shad ◽  
Alosa Alosa ◽  
Minho River

The comparative ecology and evidence for resource partitioning in two pholidid fishes (Pisces: Pholididae) from southern British Columbia eelgrass beds

1985 ◽  
Vol 63 (1) ◽  
pp. 76-85 ◽  
Author(s):  
Grant W. Hughes
Keyword(s):  
British Columbia ◽  
Activity Patterns ◽  
Prey Type ◽  
Microhabitat Use ◽  
Similar Species ◽  
Intertidal Habitat ◽  
Comparative Ecology ◽  
Saanich Inlet ◽  
Breeding Habitats ◽  
Eelgrass Beds

A comparative analysis of the ecology of sympatrically occurring Pholis laeta and Pholis ornata was conducted in Saanich Inlet, British Columbia. Summer microhabitat use of eelgrass bed depths, intertidal habitat use, prey type, and characteristic location of prey taken differed in fish older than 1 year and may have facilitated the coexistence of these morphologically similar species. Prey sizes and activity patterns were similar between species. Winter segregation of the species during the breeding season may have reduced the possibility of hybridization. Competition for breeding habitats and differences in trophic apparatus may partly explain the observed patterns of resource use.

Sign in / Sign up

Export Citation Format

Share Document