skip to main content

Attention:

The NSF Public Access Repository (PAR) system and access will be unavailable from 11:00 PM ET on Friday, December 13 until 2:00 AM ET on Saturday, December 14 due to maintenance. We apologize for the inconvenience.


Title: Anemochory of diapausing stages of microinvertebrates in North American drylands
Abstract

Dry, ephemeral, desert wetlands are major sources of windblown sediment, as well as repositories for diapausing stages (propagules) of aquatic invertebrates. Zooplankton propagules are of the same size range as sand and dust grains. They can be deflated and transported in windstorm events. This study provides evidence that dust storms aid in dispersal of microinvertebrate propagules via anemochory (aeolian transport).

We monitored 91 windstorms at six sites in the southwestern U.S.A. over a 17‐year period. The primary study site was located in El Paso, Texas in the northern Chihuahuan Desert. Additional samples were collected from the Southern High Plains region. Dust carried by these events was collected and rehydrated to hatch viable propagules transported with it.

Using samples collected over a 6‐year period, 21 m above the ground, which included 59 storm events, we tested the hypothesis that transport of propagules is correlated with storm intensity by monitoring meteorological conditions such as storm duration, wind direction, wind speed, and particulate matter (PM10; fine dust concentration). An air quality monitoring site located adjacent to the dust samplers provided quantitative hourly measurements.

Rehydration results from all events showed that ciliates were found in 92% of the samples, rotifers in 81%, branchiopods in 29%, ostracods in 4%, nematodes in 13%, gastrotrichs in 16%, and tardigrades in 3%. Overall, four bdelloid and 11 monogonont rotifer species were identified from rehydrated windblown dust samples.

Principal component analysis indicated gastrotrichs, branchiopods, nematodes, tardigrades, and monogonont rotifer occurrence positively correlated withPM10and dust event duration. Bdelloid rotifers were correlated with amount of sediment deposited. Non‐metric multidimensional scaling showed a significant relationship betweenPM10and occurrence of some taxa. Zero‐inflated, general linear models with mixed‐effects indicated significant relationships with bdelloid and nematode transport andPM10.

Thus, windstorms with highPM10concentration and long duration are more likely to transport microinvertebrate diapausing stages in drylands.

 
more » « less
PAR ID:
10461427
Author(s) / Creator(s):
 ;  ;  ;  ;  
Publisher / Repository:
Wiley-Blackwell
Date Published:
Journal Name:
Freshwater Biology
Volume:
64
Issue:
7
ISSN:
0046-5070
Page Range / eLocation ID:
p. 1303-1314
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Summary

    Traditionally, leaves were thought to be supplied withCO2for photosynthesis by the atmosphere and respiration. Recent studies, however, have shown that the xylem also transports a significant amount of inorganic carbon into leaves through the bulk flow of water. However, little is known about the dynamics and proportion of xylem‐transportedCO2that is assimilated, vs simply lost to transpiration.

    Cut leaves ofPopulus deltoidesandBrassica napuswere placed in eitherKCl or one of three [NaH13CO3] solutions dissolved in water to simultaneously measure the assimilation and the efflux of xylem‐transportedCO2exiting the leaf across light andCO2response curves in real‐time using a tunable diode laser absorption spectroscope.

    The rates of assimilation and efflux of xylem‐transportedCO2increased with increasing xylem [13CO2*] and transpiration. Under saturating irradiance, rates of assimilation using xylem‐transportedCO2accounted forc.2.5% of the total assimilation in both species in the highest [13CO2*].

    The majority of xylem‐transportedCO2is assimilated, and efflux is small compared to respiration. Assimilation of xylem‐transportedCO2comprises a small portion of total photosynthesis, but may be more important whenCO2is limiting.

     
    more » « less
  2. Summary

    Steady‐state photosyntheticCO2responses (A/Cicurves) are used to assess environmental responses of photosynthetic traits and to predict future vegetative carbon uptake through modeling. The recent development of rapidA/Cicurves (RACiRs) permits faster assessment of these traits by continuously changing [CO2] around the leaf, and may reveal additional photosynthetic properties beyond what is practical or possible with steady‐state methods.

    Gas exchange necessarily incorporates photosynthesis and (photo)respiration. Each process was expected to respond on different timescales due to differences in metabolite compartmentation, biochemistry and diffusive pathways. We hypothesized that metabolic lags in photorespiration relative to photosynthesis/respiration andCO2diffusional limitations can be detected by varying the rate of change in [CO2] duringRACiR assays. We tested these hypotheses through modeling and experiments at ambient and 2% oxygen.

    Our data show that photorespiratory delays cause offsets in predictedCO2compensation points that are dependent on the rate of change in [CO2]. Diffusional limitations may reduce the rate of change in chloroplastic [CO2], causing a reduction in apparentRACiR slopes under highCO2ramp rates.

    MultirateRACiRs may prove useful in assessing diffusional limitations to gas exchange and photorespiratory rates.

     
    more » « less
  3. Summary

    We investigated the molecular basis and physiological implications of anion transport during pollen tube (PT) growth inArabidopsis thaliana(Col‐0).

    Patch‐clamp whole‐cell configuration analysis of pollen grain protoplasts revealed three subpopulations of anionic currents differentially regulated by cytoplasmic calcium ([Ca2+]cyt). We investigated the pollen‐expressed proteinsAtSLAH3,AtALMT12,AtTMEM16 andAtCCCas the putative anion transporters responsible for these currents.

    AtCCCGFPwas observed at the shank andAtSLAH3‐GFPat the tip and shank of thePTplasma membrane. Both are likely to carry the majority of anion current at negative potentials, as extracellular anionic fluxes measured at the tip ofPTs with an anion vibrating probe were significantly lower inslah3−/−andccc−/−mutants, but unaffected inalmt12−/−andtmem16−/−. We further characterised the effect ofpHandGABAby patch clamp. Strong regulation by extracellularpHwas observed in the wild‐type, but not intmem16−/−. Our results are compatible withAtTMEM16 functioning as an anion/H+cotransporter and therefore, as a putativepHsensor.GABApresence: (1) inhibited the overall currents, an effect that is abrogated in thealmt12−/−and (2) reduced the current inAtALMT12 transfectedCOS‐7 cells, strongly suggesting the direct interaction ofGABAwithAtALMT12.

    Our data show thatAtSLAH3 andAtCCCactivity is sufficient to explain the major component of extracellular anion fluxes, and unveils a possible regulatory system linkingPTgrowth modulation bypH,GABA, and [Ca2+]cytthrough anionic transporters.

     
    more » « less
  4. Summary

    Mesophyll conductance (gm) is the diffusion ofCO2from intercellular air spaces (IAS) to the first site of carboxylation in the mesophyll cells. In C3species,gmis influenced by diverse leaf structural and anatomical traits; however, little is known about traits affectinggmin C4species.

    To address this knowledge gap, we used online oxygen isotope discrimination measurements to estimategmand microscopy techniques to measure leaf structural and anatomical traits potentially related togmin 18 C4grasses.

    In this study,gmscaled positively with photosynthesis and intrinsic water‐use efficiency (TEi), but not with stomatal conductance. Also,gmwas not determined by a single trait but was positively correlated with adaxial stomatal densities (SDada), stomatal ratio (SR), mesophyll surface area exposed toIAS(Smes) and leaf thickness. However,gmwas not related to abaxial stomatal densities (SDaba) and mesophyll cell wall thickness (TCW).

    Our study suggests that greaterSDadaandSRincreasedgmby increasingSmesand creating additional parallel pathways forCO2diffusion inside mesophyll cells. Thus,SDada,SRandSmesare important determinants of C4gmand could be the target traits selected or modified for achieving greatergmandTEiin C4species.

     
    more » « less
  5. Abstract Practitioner Points

    Staphylococcus aureusconcentrations, survival, and persistence were assessed in environmental fresh and brackish waters.

    Experimental design preserved in situ conditions to measureS. aureussurvival.

    Higher initialS. aureusconcentrations were observed in fresh waters with elevated turbidity, while sustained persistence was greater in brackish waters.

    Water turbidity and salinity were both positively associated withS. aureusconcentrations and persistence.

    Climate change leads to more intense rainfall events which increase water turbidity and pathogen loading, heightening the exposure risk toS. aureus.

     
    more » « less