| General Information: |
| Title: | Individual-based food web (Guadalquivir estuary, southern Spain) |
| Identifier: | knb.248 |
| Abstract: |
Stomach contents and estimates of abundance were collected monthly from February 1998 to January 1999 at three locations in the estuary of the Guadalquivir river, southern Spain. Samples were taken across a range of different environmental conditions, with seasonal variations in temperature and spatial variations in salinity.
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| Keywords: | None:
- Stomach content and individual data
- Individual-based food web
- Diversity in space and time
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Publication Date: | 2010-06-21 |
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Involved Parties
| Data Set Creators: |
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Organization: | Instituto de Ciencias Marinas de Andalucia |
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Individual: | Pilar Drake |
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Organization: | Instituto de Ciencias Marinas de Andalucia |
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Address: |
| Apdo. Oficial, Puerto Real, |
| Cadiz, 11510 Spain |
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Email Address:
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| Data Set Contacts: |
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Individual: | Pilar Drake |
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Organization: | Instituto de Ciencias Marinas de Andalucia |
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Address: |
| Apdo. Oficial, Puerto Real, |
| Cadiz, 11510 Spain |
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Email Address:
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| Associated Parties: |
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| Metadata Providers: |
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Individual: | Carlos Melian |
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Data Set Characteristics
| Geographic Region: |
| Geographic Description: | The Guadalquivir river estuary (SW Spain: 37^{o} 15^' –
36^{o} 45^{'}N, 6^{o} 00^{'} - 6^{o}22^{'}W) is vertically
mixed, shows a longitudinal salinity gradient and a completely mixed water column. As most temperate and well-mixed estuaries, its maximum turbidity zone is in the oligohaline region. The tidal influence reaches about 110km up stream from the river mouth and the mean tidal range is 3.5m in the outer estuary.
We located our sampling sites at Tarfia (36^{o} 57^{'} 30^{''}N - 6^{o} 10^{'} 37^{''}W), in the oligohaline estuarine region (mean ± SE salinity = 3.7 ± 0.3 and
turbidity = 74.9 ± 8.8 NTU, nephelometer turbidity units), Esparraguera (36 ^{o} 54 ^{'} 6^{''}N - 6^{o} 16^{'} 12^{''}W), in the mesohaline estuarine region (mean ± SE salinity = 8.5 ± 0.8 and turbidity = 69.3 ± 7.2 NTU), and Bonanza (36^{o} 52^{'} 2^{''}N -6^{o} 20^{'} 53^{''}W), in the polyhaline region (mean ± SE salinity = 19.9 ± 1.5 and turbidity = 42.3 ± 5.2 NTU), situated at 32, 20 and 8 km, respectively from the river’s mouth, with all sampling sites approximately being 3m in depth
at low tide. The temperature was spatially homogeneous throughout the estuary (mean ± SE temperature = 19.4 ± 0.8°C and 19.3 ± 0.8^{o}C at Tarfia and Bonanza, respectively), but with a marked seasonal variation (mean ± SE temperature = 10.5 ± 0.18^{o}C
and 27.1 ± 0.25^{o}C in January and August, respectively). |
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Bounding Coordinates:
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| West: | -6.3667 degrees
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| East: | -6.3667 degrees
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| North: | 37.2500 degrees
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| South: | 37.2500 degrees
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Sampling, Processing and Quality Control Methods
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Step by Step Procedures
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| Step 1: |
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Description:
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Fish stomach content and estimation of mysid abundance
Stomach contents and estimations of abundance in the three stations were collected from February 1998 to January 1999 (12 months) following the periodicity associated with the moon cycle.
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Sampling Area And Frequency:
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Estimations of abundance were collected in each of the three stations with a total of 144 samplings (12 months x 3 stations x 4 samplings). At each new moon, 4 samplings were collected in each station during a period of 24h and synchronized with tides (two in the starting point of the ``low tides'' and two in starting point of ``high tides'').
All samples were caught from traditional fish boat anchored on the left river side. Samples consisted of passive hauls, lasting 2h, made during the first 2h of each diurnal and nocturnal flood and ebb tide. Samplings were taken with three nets working in parallel. Nets were made with polyamide gauze from a mesh of 1mm and an opening of
25m (width) and 3m (depth).
The total catch from each sampling was discharged into a calibrated container and its volume estimated. Thirteen liters of the collected material, or the total volume when the catch was smaller, were randomly sampled using a calibrated (1 liter) beaker and preserved in 10% formaldehyde. In the laboratory, individuals were sorted into species, counted, and analyzed. At the start of each sampling, water temperature, salinity and turbidity were measured. During sampling, the current speed was measured with a digital flow meter placed near the nets, so abundance of the different species are given per 10^5 m^3 of filtered water.
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Sampling Description:
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Stomach contents of the 10 most abundant fish species were analyzed in two of the stations (i.e., Tarfia and Bonanza) with a total of 96 samplings (12 months x 2 stations x 4 samplings). Most fishes caught were small sized, including mainly postlarvae and juveniles, but also adults of small resident species. Every individual mysid prey found in
the stomach content of each of the 5725 small (total length (TL) < 140mm) fish was identified to species level.
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Data Set Usage Rights
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Obtain permission from data set owner(s)
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