Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Variability in click-evoked potentials in killer whales (Orcinus orca) and determination of a hearing impairment in a rehabilitated killer whale
Lucke, K. ; Finneran, J.J. ; Almunia, Javier ; Houser, D.S. - \ 2016
Aquatic mammals 42 (2016)2. - ISSN 0167-5427 - p. 184 - 192.
killer whales - Orcinus orca - marine mammal - audiometry - auditory evoked potentials - hearing deficit
An immature female killer whale (Orcinus orca) stranded in the Wadden Sea in 2010 and was later transferred to Loro Parque, Tenerife, Spain, for rehabilitation. The killer whale, named “Morgan,” was suspected to have a hearing impairment. To test whether Morgan has a hearing deficit, auditory brainstem responses to short-duration, broadband click stimuli were recorded. The same procedure was conducted with five other killer whales at Loro Parque for comparative purposes. Stereotypical click-evoked responses were recorded in all of the killer whales except Morgan, even at the highest click level that could be projected. Reductions in the amplitude of the click-evoked response paralleled reductions in the stimulus amplitude of the clicks presented to all of the other whales. The lack of a click-evoked response in Morgan indicates that she suffers from a hearing deficit. The magnitude and frequency range over which the hearing deficit occurs cannot be specified with the techniques used here. Nevertheless, it can be concluded that Morgan’s hearing sensitivity to broadband signals is at least 20 to 30 dB worse than the hearing sensitivity of the other killer whales tested. Morgan potentially suffers from a profound hearing deficit or even a complete loss of hearing, but this cannot be determined through the electrophysiological tests used in this experiment.
In-Air Evoked Potential Audiometry of Grey Seals (Halichoerus grypus) from the North and Baltic Seas
Ruser, A. ; Daehne, M. ; Sundermeyer, J. ; Lucke, K. ; Houser, D.S. ; Finneran, J.J. ; Driver, J. ; Pawliczka, I. ; Rosenberger, T. ; Siebert, U. - \ 2014
PLoS One 9 (2014)3. - ISSN 1932-6203 - 8 p.
lion zalophus-californianus - temporary threshold shift - hearing sensitivity - phoca-vitulina - mirounga-angustirostris - tursiops-truncatus - amphibious hearing - harbor seals - underwater - pinnipeds
In-air anthropogenic sound has the potential to affect grey seal (Halichoerus grypus) behaviour and interfere with acoustic communication. In this study, a new method was used to deliver acoustic signals to grey seals as part of an in-air hearing assessment. Using in-ear headphones with adapted ear inserts allowed for the measurement of auditory brainstem responses (ABR) on sedated grey seals exposed to 5-cycle (2-1-2) tone pips. Thresholds were measured at 10 frequencies between 1–20 kHz. Measurements were made using subcutaneous electrodes on wild seals from the Baltic and North Seas. Thresholds were determined by both visual and statistical approaches (single point F-test) and good agreement was obtained between the results using both methods. The mean auditory thresholds were =40 dB re 20 µPa peak equivalent sound pressure level (peSPL) between 4–20 kHz and showed similar patterns to in-air behavioural hearing tests of other phocid seals between 3 and 20 kHz. Below 3 kHz, a steep reduction in hearing sensitivity was observed, which differed from the rate of decline in sensitivity obtained in behavioural studies on other phocids. Differences in the rate of decline may reflect influence of the ear inserts on the ability to reliably transmit lower frequencies or interference from the structure of the distal end of the ear canal.
Assessment of basic audiometric functions in killer whales (Orcinus orca) at Loro Parque, Tenerife, Spain
Lucke, K. ; Finneran, J.J. ; Houser, D.S. - \ 2013
Den Helder : IMARES (Rapport / IMARES Wageningen UR C045/13) - 15
whales - hearing impairment - electrophysiology - hearing - walvissen - gehoorvermindering - elektrofysiologie - gehoor
Existing degrees of consolidation
Dirmeyer, P.A. ; Feddes, R.A. ; Hall, F.G. ; Halldin, S. ; Hoff, H. ; Houser, P. ; Hutjes, R.W.A. ; Jenne, R. ; Leese, J. ; Kittel, T. ; Meeson, B.W. ; Olson, R.J. ; Phillips, T.J. ; Pitman, A.J. ; Takahashi, K. ; Verdin, K. - \ 2004
In: Vegetation, water, humans and the climate; a new perspective on an interactive system / Kabat, P., Claussen, M., Dirmeyer, P.A., Gash, J.H.C., Bravo de Guenni, L., Meybeck, M., Pielke sr., R.A., Vörösmarty, C.J., Hutjes, R.W.A., Lütkemeier, S., Berlin (Germany) [etc.] : Springer (IGBP Series ) - ISBN 3540424008 - p. 255 - 265.
Ground-based investigation of soil moisture variability within remote sensing footprints during the Southern Great Plains 1997 (SGP97) Hydrology Experiment
Famiglietti, J.S. ; Devereaux, J.A. ; Laymon, C.A. ; Tsegaye, T. ; Houser, P.R. ; Jackson, T.J. ; Graham, S.T. ; Rodell, M. ; Oevelen, P.J. van - \ 1999
Water Resources Research 35 (1999)6. - ISSN 0043-1397 - p. 1839 - 1851.
Surface soil moisture content is highly variable in both space and time. While remote sensing provides an effective methodology for mapping surface moisture content over large areas, it averages within-pixel variability thereby masking the underlying heterogeneity observed at the land surface. This variability must be better understood in order to rigorously evaluate sensor performance and to enhance the utility of the larger-scale remotely sensed averages by quantifying the underlying variability that remote sensing cannot record explicitly. In support of the Southern Great Plains 1997 (SGP97) Hydrology Experiment (a surface soil moisture mapping mission conducted between June 18 and July 17, 1997, in central Oklahoma) an investigation was conducted to characterize soil moisture variability within remote sensing footprints (approximately 0.64 km2) with more certainty than would be afforded with conventional gravimetric moisture content sampling. Nearly every day during the experiment period, portable impedance probes were used to intensively monitor volumetric moisture content in the 0- to 6-cm surface soil layer at six footprint-sized fields scattered over the SGP97 study area. A minimum of 49 daily moisture content measurements were made on most fields. Higher-resolution grid and transect data were also collected periodically. In total, more than 11,000 impedance probe measurements of volumetric moisture content were made at the six sites by over 35 SGP97 participants. The wide spatial distribution of the sites, combined with the intensive, near-daily monitoring, provided a unique opportunity (relative to previous smaller-scale and shorter-duration soil moisture studies) to characterize variations in surface moisture content over a range of wetness conditions. In this paper the range and temporal dynamics of the variability in moisture content within each of the six fields are described, as are general relationships between the variability and footprint-mean moisture content. Results indicate that distinct differences in mean moisture content between the six sites are consistent with variations in soil type, vegetation cover, and rainfall gradients. Within fields the standard deviation, coefficient of variation, skewness, and kurtosis increased with decreasing moisture content; the distribution of surface moisture content evolved from negatively skewed/nonnormal under very wet conditions, to normal in the midrange of mean moisture content, to positively skewed/nonnormal under dry conditions; and agricultural practices of row tilling and terracing were shown to exert a major control on observed moisture content variations. Results presented here can be utilized to better evaluate sensor performance, to extrapolate estimates of subgrid-scale variations in moisture content across the entire SGP97 region, and in the parameterization of soil moisture dynamics in hydrological and land surface models. | Surface soil moisture content is highly variable in both space and time. While remote sensing provides an effective methodology for mapping surface moisture content over large areas, it averages within-pixel variability thereby masking the underlying heterogeneity observed at the land surface. This variability must be better understood in order to rigorously evaluate sensor performance and to enhance the utility of the larger-scale remotely sensed averages by quantifying the underlying variability that remote sensing cannot record explicitly. In support of the Southern Great Plains 1997 (SGP97) Hydrology Experiment (a surface soil moisture mapping mission conducted between June 18 and July 17, 1997, in central Oklahoma) an investigation was conducted to characterize soil moisture variability within remote sensing footprints (approximately 0.64 km2) with more certainty than would be afforded with conventional gravimetric moisture content sampling. Nearly every day during the experiment period, portable impedance probes were used to intensively monitor volumetric moisture content in the 0- to 6-cm surface soil layer at six footprint-sized fields scattered over the SGP97 study area. A minimum of 49 daily moisture content measurements were made on most fields. Higher-resolution grid and transect data were also collected periodically. In total, more than 11,000 impedance probe measurements of volumetric moisture content were made at the six sites by over 35 SGP97 participants. The wide spatial distribution of the sites, combined with the intensive, near-daily monitoring, provided a unique opportunity (relative to previous smaller-scale and shorter-duration soil moisture studies) to characterize variations in surface moisture content over a range of wetness conditions. In this paper the range and temporal dynamics of the variability in moisture content within each of the six fields are described, as are general relationships between the variability and footprint-mean moisture content. Results indicate that distinct differences in mean moisture content between the six sites are consistent with variations in soil type, vegetation cover, and rainfall gradients. Within fields the standard deviation, coefficient of variation, skewness, and kurtosis increased with decreasing moisture content; the distribution of surface moisture content evolved from negatively skewed/nonnormal under very wet conditions, to normal in the midrange of mean moisture content, to positively skewed/nonnormal under dry conditions; and agricultural practices of row tilling and terracing were shown to exert a major control on observed moisture content variations. Results presented here can be utilized to better evaluate sensor performance, to extrapolate estimates of subgrid-scale variations in moisture content across the entire SGP97 region, and in the parameterization of soil moisture dynamics in hydrological and land surface models.
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