Feeding dynamics of the fiddler crab (Uca annulipes) in a non-tidal mangrove forest

2016 ◽  
Vol 67 (5) ◽  
pp. 556 ◽  
Author(s):  
N. Peer ◽  
N. A. F. Miranda ◽  
R. Perissinotto ◽  
J. L. Raw
Keyword(s):  
Fiddler Crab ◽  
Austral Summer ◽  
Grazing Impact ◽  
Evacuation Rate ◽  
Uca Annulipes ◽  
Gut Evacuation ◽  
Gut Pigment ◽  
Consumption Efficiency ◽  
Gut Fluorescence

To investigate the lack of tidal influence on the feeding dynamics of fiddler crabs, we used an in situ gut fluorescence technique to measure gut pigment content of Uca annulipes in the non-tidal mangrove habitat of the St Lucia Estuary. Measurements were taken over a 24-h cycle and in the two extreme seasons, austral summer and winter, to examine any diel and seasonal shifts in feeding. Three hour gut evacuation experiments were conducted to determine the gut evacuation rate and potential sexual differences in feeding. It was found that under lack of tidal fluctuations, U. annulipes feeding is influenced by diel rhythms. In summer, males displayed a bimodal pattern of feeding, becoming more active in the morning and late afternoon with a gut evacuation rate of 0.795h–1, whereas females remained generally inactive and displayed short bouts of feeding during the day with a gut evacuation rate of 0.322h–1. The summer grazing impact of U. annulipes on microphytobenthos was higher compared with winter. In winter both sexes were fairly inactive, but displayed a greater consumption efficiency (65% compared with 45% in summer). U. annulipes feeding dynamics in a non-tidal habitat are shown to vary seasonally, daily and among sexes.

scholarly journals Gut evacuation rate and grazing impact of the krill Thysanoessa raschii and T. inermis

2014 ◽  
Vol 162 (1) ◽  
pp. 169-180 ◽  
Author(s):  
Frederik Wolff Teglhus ◽  
Mette Dalgaard Agersted ◽  
Kristine Engel Arendt ◽  
Torkel Gissel Nielsen
Keyword(s):  
Grazing Impact ◽  
Evacuation Rate ◽  
Gut Evacuation

scholarly journals Safe sex: male–female coalitions and pre-copulatory mate-guarding in a fiddler crab

2009 ◽  
Vol 6 (2) ◽  
pp. 180-182 ◽  
Author(s):  
Richard N. C. Milner ◽  
Michael D. Jennions ◽  
Patricia R. Y. Backwell
Keyword(s):  
Sexual Dimorphism ◽  
Reproductive Success ◽  
Observational Data ◽  
Fiddler Crab ◽  
Lower Boundary ◽  
Mate Guarding ◽  
Maintenance Costs ◽  
Boundary Maintenance ◽  
Uca Annulipes ◽  
Males And Females

In fiddler crabs both males and females defend territories that are essential for survival. Given pronounced sexual dimorphism in weaponry, how do weaponless females defend their territory from well-armed males? Using observational data and two simple experiments, we test whether male Uca annulipes protect their female neighbours from conspecific intruders. We show that males defend their female neighbours against male but not female intruders. We also show that females sometimes mate with their immediate neighbours. Male defence of female neighbours appears to represent both pre-copulatory mate-guarding and a territorial coalition. Males who ensure that their neighbour remains female could benefit through increased opportunity for future reproductive success and lower boundary maintenance costs.

scholarly journals IDENTIFIKASI JENIS KEPITING BIOLA DI HUTAN MANGROVE DUSUN SETINGGA ASINDESA SEBUBUS KECAMATAN PALOH KABUPATEN SAMBAS

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Edy Kurniawan ◽  
M Sofwan Anwari ◽  
M Dirhamsyah
Keyword(s):  
Sampling Method ◽  
Fiddler Crab ◽  
Sandy Beaches ◽  
Mangrove Forests ◽  
Crab Species ◽  
Fiddler Crabs ◽  
Purposive Sampling ◽  
Plot Size ◽  
Uca Annulipes

The fiddler crab is also known as the kepiting biola is an animal that has broad legs that belong to the Crustacean class. Fiddler crab is a type of crab that has a habitat in intertidal areas, especially around mangrove forests and sandy beaches. This study aims to examine the identification of fiddler crab species found in the Mangrove Sebubus. The method used in this research is purposive sampling method with the use of a square plot size of 1 x 1 meter as many as 30 pieces in 3 research lines. The results showed as many as 7 species of fiddler crabs found there, that is Uca annulipes, Uca rosea, Uca forcipata, Uca bellator, Uca tetragonon, Uca paradussumieri, and Uca acuta.Keywords: Identification, Fiddler Crab, Mangrove Sebubus

Swell Genesis, Modelling and Measurements in West Africa

2013 ◽  
Author(s):  
Marc Prevosto ◽  
Kevin Ewans ◽  
George Z. Forristall ◽  
Michel Olagnon
Keyword(s):  
West Africa ◽  
Numerical Models ◽  
Austral Summer ◽  
In Situ Measurements ◽  
West African ◽  
The South ◽  
West African Coast ◽  
Westerly Direction ◽  
Propagation Of Waves

Swell events show a large variety of configurations when they arrive at sites off West Africa after generation and propagation of waves across the Atlantic Ocean. Within the West Africa Swell Project (WASP JIP), these different configurations have been described and discussed and the ability of numerical models to reproduce faithfully their properties has been assessed from comparisons with in-situ measurements. During the austral winter months, swells approach West African coast from the south to south-westerly direction. These swells are generated by storms in the South Atlantic mainly between 40°S and 60°S. But during austral summer, north-westerly swells are also observed coming from North Atlantic. Typical situations of superposition of these different swells are illustrated in the paper. In spite of a poor overlapping between numerical and in-situ measurements databases at the time of the WASP project, and of reduced durations of measurement campaigns, comparisons between in situ measurements and hindcast models permitted identification of the limitations of the different numerical models available. Three sites have been used for this study, one in the Gulf of Guinea with directional Waverider and Wavescan buoys, a second one off Namibia with a directional Waverider and one last instrumented with two wavestaffs off Cabinda (Angola). In addition, the existence of infra-gravity waves in shallow water measurements has been investigated.

scholarly journals Contribution and pathways of diazotroph-derived nitrogen to zooplankton during the VAHINE mesocosm experiment in the oligotrophic New Caledonia lagoon

2016 ◽  
Vol 13 (10) ◽  
pp. 3131-3145 ◽  
Author(s):  
Brian P. V. Hunt ◽  
Sophie Bonnet ◽  
Hugo Berthelot ◽  
Brandon J. Conroy ◽  
Rachel A. Foster ◽  
...  
Keyword(s):  
N2 Fixation ◽  
New Caledonia ◽  
Austral Summer ◽  
Zooplankton Community ◽  
Zooplankton Biomass ◽  
Diazotrophic Cyanobacteria ◽  
Subtropical Oceans ◽  
Isotope Mixing Models

Abstract. In oligotrophic tropical and subtropical oceans, where strong stratification can limit the replenishment of surface nitrate, dinitrogen (N2) fixation by diazotrophs can represent a significant source of nitrogen (N) for primary production. The VAHINE (VAriability of vertical and tropHIc transfer of fixed N2 in the south-wEst Pacific) experiment was designed to examine the fate of diazotroph-derived nitrogen (DDN) in such ecosystems. In austral summer 2013, three large ( ∼  50 m3) in situ mesocosms were deployed for 23 days in the New Caledonia lagoon, an ecosystem that typifies the low-nutrient, low-chlorophyll environment, to stimulate diazotroph production. The zooplankton component of the study aimed to measure the incorporation of DDN into zooplankton biomass, and assess the role of direct diazotroph grazing by zooplankton as a DDN uptake pathway. Inside the mesocosms, the diatom–diazotroph association (DDA) het-1 predominated during days 5–15 while the unicellular diazotrophic cyanobacteria UCYN-C predominated during days 15–23. A Trichodesmium bloom was observed in the lagoon (outside the mesocosms) towards the end of the experiment. The zooplankton community was dominated by copepods (63 % of total abundance) for the duration of the experiment. Using two-source N isotope mixing models we estimated a mean  ∼  28 % contribution of DDN to zooplankton nitrogen biomass at the start of the experiment, indicating that the natural summer peak of N2 fixation in the lagoon was already contributing significantly to the zooplankton. Stimulation of N2 fixation in the mesocosms corresponded with a generally low-level enhancement of DDN contribution to zooplankton nitrogen biomass, but with a peak of  ∼  73 % in mesocosm 1 following the UCYN-C bloom. qPCR analysis targeting four of the common diazotroph groups present in the mesocosms (Trichodesmium, het-1, het-2, UCYN-C) demonstrated that all four were ingested by copepod grazers, and that their abundance in copepod stomachs generally corresponded with their in situ abundance. 15N2 labelled grazing experiments therefore provided evidence for direct ingestion and assimilation of UCYN-C-derived N by the zooplankton, but not for het-1 and Trichodesmium, supporting an important role of secondary pathways of DDN to the zooplankton for the latter groups, i.e. DDN contributions to the dissolved N pool and uptake by nondiazotrophs. This study appears to provide the first evidence of direct UCYN-C grazing by zooplankton, and indicates that UCYN-C-derived N contributes significantly to the zooplankton food web in the New Caledonia lagoon through a combination of direct grazing and secondary pathways.

scholarly journals Measurement and interpretation of gas phase formaldehyde concentrations obtained during the CHABLIS campaign in coastal Antarctica

2008 ◽  
Vol 8 (14) ◽  
pp. 4085-4093 ◽  
Author(s):  
R. A. Salmon ◽  
S. J.-B. Bauguitte ◽  
W. Bloss ◽  
M. A. Hutterli ◽  
A. E. Jones ◽  
...  
Keyword(s):  
Gas Phase ◽  
Austral Summer ◽  
Research Station ◽  
Steady State Analysis ◽  
Sources And Sinks ◽  
Data Coverage ◽  
Absolute Concentrations ◽  
Instrumental Detection Limit ◽  
Phase Production

Abstract. Gas phase formaldehyde concentrations were measured during the 2004–2005 CHABLIS campaign at Halley research station, Antarctica. Data coverage span from May 2004 through to January 2005, thus capturing the majority of the year, with a wintertime minimum of near or below the instrumental detection limit rising to between 50 and 200 pptv during the austral summer. Factors controlling HCHO concentration include local chemical sources and sinks, and exchange with the snow surface. The measured seasonality is in line with previous observations from Neumayer station, with maximum in summer and minimum during the winter months, but with lower absolute concentrations throughout the year. The gas-phase production of HCHO was dominated by methane oxidation and a steady-state analysis showed that reactions of iodine and bromine species substantially reduced the predicted HCHO levels based upon in situ chemistry. This indicates a substantial additional HCHO source to be present that could be explained by a snowpack source.

How French shepherds create meal sequences to stimulate intake and optimise use of forage diversity on rangeland

2015 ◽  
Vol 55 (3) ◽  
pp. 309 ◽  
Author(s):  
Michel Meuret ◽  
Fred Provenza
Keyword(s):  
Daily Intake ◽  
Animal Husbandry ◽  
Simultaneous Recording ◽  
Grazing Impact ◽  
Collective Effort ◽  
Scientific Disciplines ◽  
Types Of Information ◽  
Forage Diversity ◽  
Different Levels

European rangelands have rugged terrain with highly diverse patchworks of vegetation communities. They are mostly public lands that were abandoned for more than 50 years, because they served no purpose at the time of animal husbandry modernisation. The European Union’s policy now promotes the reintroduction of grazing on rangelands to prevent wildfires and to restore habitats for biodiversity conservation. Facing the lack of knowledge to implement such a policy, researchers, nature managers, and pastoral advisors began working closely with shepherds and goat herders in France, who had persisted in using rangelands. The research presented here is part of this collective effort to understand and assess the experiential knowledge and feeding practices that herders use for livestock. The study required in situ and simultaneous recording of several types of information at different levels of organisation – herder, herd, individual animal – using methods from scientific disciplines ranging from ethnology to animal behavioural ecology and landscape ecology. The results for herded animals were surprising; they had daily intake levels often twice those observed in controlled studies with forages of similar nutritive values. The reason became clear when we learned that herders use grazing circuits that sequence a meal into a succession of contrasting and complementary grazing ‘sectors’ that boost appetite and intake. Our modelling of this practice in MENU, a model conceived and developed with experienced herders, shows how a herder can use understanding of complementarities among sectors to sequence meals that increase appetite and intake and ensure renewal of resources at the landscape level, or conversely, to apply more intensive grazing impact on particular target sectors.

scholarly journals DMS and MSA measurements in the Antarctic boundary layer: impact of BrO on MSA production

2008 ◽  
Vol 8 (1) ◽  
pp. 2657-2694 ◽  
Author(s):  
K. A. Read ◽  
A. C. Lewis ◽  
S. Bauguitte ◽  
A. M. Rankin ◽  
R. A. Salmon ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Austral Summer ◽  
Atmospheric Concentration ◽  
Air Masses ◽  
Average Value ◽  
Number Of Factors ◽  
Spatial Coverage ◽  
Antarctic Boundary Layer ◽  
The Antarctic

Abstract. In situ measurements of dimethyl sulphide (DMS) and methane sulphonic acid (MSA) were made at Halley Station, Antarctica (75°35´S, 26°19W) during February 2004–February 2005 as part of the CHABLIS (Chemistry of the Antarctic boundary layer and the interface with snow) project. DMS was present in the atmosphere at Halley all year (average 38.1±43 pptV) with a maximum monthly average value of 113.6±52 pptV in February 2004 coinciding temporally with a minimum in sea extent. Whilst seasonal variability and interannual variability can be attributed to a number of factors, short term variability appeared strongly dependent on air mass origin and trajectory pressure height. The MSA and derived non-sea salt sulphate (nss-SO42−) measurements showed no correlation with those of DMS (regression R2=0.039, and R2=0.001, respectively) in-line with the complexity of DMS fluxes, conflicting oxidation routes, transport of air masses and variable spatial coverage of both sea-ice and phytoplankton. MSA was generally low throughout the year, with an annual average of 42 ng m−3 (9.8±13.2 pptV), however MSA: nss-SO42− ratios were high implying a dominance of the addition oxidation route for DMS. Including BrO measurements into MSA production calculations demonstrated the significance of BrO on DMS oxidation within this region of the atmosphere in austral summer. Assuming an 80% yield of DMSO from the reaction of DMS+BrO, an atmospheric concentration of BrO equal to 3 pptV increased the calculated MSA production from DMS by a factor of 9 above that obtained when considering only reaction with the hydroxyl radical.

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