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Functional role of native and invasive filter-feeders, and the effect of parasites: learning from hypersaline ecosystems [Dataset]. 2016

AutorSánchez, Marta I. ; Paredes, Irene; Lebouvier, Marion; Green, Andy J.
Palabras claveArtemia
Filter-feeders, hypersaline ecosystems
Fecha de publicación2016
CitaciónFunctional role of native and invasive filter-feeders, and the effect of parasites: learning from hypersaline ecosystems
ResumenArtemia franciscana vs A. parthenogenetica. Artemia sampling was conducted during November 2012 in two different salt pan complexes located along the Atlantic coast of South West Spain. Native A. parthenogenetica was collected from Odiel saltpans (Huelva 37°15'29"N, 6°58'25"W). Invasive A. franciscana were collected from La Tapa saltpans (Cádiz Bay 36º35’52”N, 06º13’07”W). In each locality, Artemia were collected from two separate evaporation ponds with distinct salinities (90 and 145 g/l). Artemia was sampled using a 0.5 mm mesh net, then they were immediately transported to the laboratory and transferred to plastic tanks containing aerated water from the same pond, and subjected to a natural photoperiod. Feeding rates were quantified at two salinities (90 and 145 g/l) and two temperatures (15 and 24 ºC). Prior to measuring feeding, individuals were acclimated for 12 hours in climatic chambers under experimental conditions (15ºC-90g/l, 15ºC-145g/l, 24ºC-90g/l or 24ºC-145g/l). Individuals were assigned to the experimental salinity that matched what they were exposed to in the field. We then selected 48 adult brine shrimps of similar size for each temperature-salinity treatment. We transferred them to Petri plates containing filtered (0.45 μm) and autoclaved water from the pond at the same salinity and temperature during 1h without food, in order to increase feeding motivation. To measure feeding rates, brine shrimps were placed individually into multi-well plates filled with 2.5 ml of freeze-dried green algae Tetraselmis chuii (EasyAlgae®, Spain) solution (algal concentration 0.2 mg/ml) and placed in climatic chambers at 24ºC and 15ºC. We prepared control and blank samples in triplicate for each treatment. Artemia individuals grazed during 4 hours under continuous light conditions. During this period, we gently agitated the water every 30 min with a plastic Pasteur pipette, to avoid food particle sedimentation at the bottom of the plates. At the end of the experiment we collected 1ml from each well and counted remaining algal particles using an EasyCyte Plus System flow cytometer (Guava Express Plus software). The number of consumed cells was calculated by subtracting the final number of cells from the initial number. For triplicate controls and blanks, samples of 1 ml were taken and counted before and after the experiment. Brine shrimps were anaesthetized with carbonated water before being mounted (sacrificed) in a temporary glycerol mount and examined under the microscope to confirm that no cestode parasites were present. We measured the length of each individual from the end of the abdomen (furca) to the top of the head using a stereomicroscope coupled with a videocamera (Axiovision software). Infected vs uninfected A. parthenogenetica. Artemia sampling was conducted at Odiel saltpans in spring 2013, from ponds of intermediate salinity where the prevalence of the cestodes Flamingolepis liguloides (hereafter FL), Anomotaenia tringae (AT, a shorebird parasite) and Confluaria podicipina (CP) was high (FL: pond E15 at 130g/l on 02/05/2013; AT and CP: pond E18 at 170g/l on 04/06/2013). We used the above experimental setup but with fixed temperature and salinity conditions. We conducted two independent experiments on the above dates, one for FL and another for CP-AT under similar conditions. Experiments were carried out at 130g/l salinity with a 0.2mg/l concentration of Tetraselmis chuii, calculating feeding rates as described above. Individuals collected from pond E18 were first acclimated to the experimental salinity for 12h. After 4 hours, all individuals were measured and their parasitic status confirmed as described above. Parasite identification followed Georgiev et al., 2005. For the first experiment we used 43 non-infected (hereafter NI) individuals and 55 infected with FL; for the second experiment we used 40 NI Artemia, 14 infected with CP and 27 with AT.
Field study Temporal variation of chlorophyll-a concentration in relation to Artemia density and species. Samples of A. parthenogenetica (from Odiel) and A. franciscana (from La Tapa) were collected monthly (from April to December 2011) from three to four ponds of different salinity, by sweeping water at each point during 15 seconds from the entire water column (15-30 cm depth) using a net of 0.1 mm mesh. Given the highly patchy distribution of Artemia in the field, 10 to 20 points were selected at random from different parts of the pond including the center and shoreline. In some ponds there were no Artemia, for reasons that are unclear but are likely to include the abundance of predators such as fish at low salinities. At each pond, we measured temperature and salinity (with a refractometer) and collected unfiltered water samples for analysis of concentrations of chlorophyll-a (as a measure of phytoplankton abundance) and nutrients. Total nitrogen concentration (Total N) was measured by digestion with potassium persulfate (Sims, Ellsworth & Mulvaney, 1995). Total phosphorus concentration (Total P) was measured by the phosphomolybdate method (APHA, 1995). Chlorophyll-a analysis was performed by spectrophotometry using the trichromatic method (Strickland and Parsons 1968). Total (including all developmental stages: metanauplii, juveniles and adults) and adult Artemia density were determined in the laboratory. Spatial variation in chlorophyll-a concentration and turbidity in relation to A. parthenogenetica density and parasite prevalence. On 23/04/2013 we sampled A. parthenogenetica (at Odiel) by filtering 20 l through a 0.5 mm mesh net, at nine different ponds covering a wide range of salinities (75-235 g/l, S1 Table). Samples of water (1 l) were taken for chlorophyll-a analysis, following the above procedure. Salinity was measured with a refractometer and turbidity with a Snell tube (a modified Secchi disc suitable for shallow waters). In the laboratory the density of Artemia (adult density, plus total density including metanauplii and juveniles) as well as the total biomass (dry mass after 24h at 50ºC) was determined. Adult individuals (n = 100) from each pond were then randomly selected for calculation of parasite prevalence (using the above methods) so as to explore the effect of parasite infection on chlorophyll-a concentration and turbidity.
DescripciónDatasets as supporting information to the article “Functional role of native and invasive filter-feeders, and the effect of parasites: learning from hypersaline ecosystems” to be published in PLOS ONE. Primary contact for data associated with this article: Marta I. Sánchez. marta.sanchezl@ebd.csic.es.
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