Benthic communities and environmental parameters in Amvrakikos Wetlands: Mazoma, Tsopeli,Tsoukalio, Rodia and Logarou lagoons (September 2010 – July 2011)

Study Extent

seasonally (4 seasons) records of zoobenthic communities across confinement gradient in 5 coastal lagoons (Mazoma, Tsopeli,Tsoukalio, Rodia and Logarou)

Sampling

box corer for 0.03 square meters area sampled Sediment temperature was measured by means of a thermometer in the first centimeter of the sediments; salinity, conductivity, water temperature, dissolved oxygen and pH were measured in the water overlaying the sediments by means of a portable multi-parameter. Redox potential of the first centimeter of the sediments was measured by means of a portable probe which was previously immersed in Zobell solution (Zobell, 1946). Sediment samples were collected from all stations by means of a modified manually-operated box-corer. Samples were collected from fishing boats specifically used at the lagoons. Cylindrical sampling corers (internal sampling surface 15.90 square centimeters) were placed inside the box-corer and sub-samples of the sediment’s upper layer (0-2 cm) were collected from each of them. Samples were collected for the determination of the concentration of the Total Reduced Inorganic Sulfur (TRIS). TRIS is the sum of Acid Volatile Sulfides (AVS), i.e. hydrogen sulfide (H2S) and iron sulfide (FeS), and Chromium Reducible Sulfur (CRS), i.e. elemental sulfur (S0) and iron pyrite (FeS2). Samples of about 8 cubic centimeters were collected from the sediment's upper layer and were immediately placed on 50 ml falcon tubes, with tapered bottom, containing 10 ml of zinc acetate solution 20% (w/v). The samples were mixed in order to allow the total surface of the sediment to come in contact with the solution and were subsequently stored at -20 oC, until further processing in the Marine Ecology Laboratory of the University of Crete, in accordance with the hot distillation method (Kallmeyer et al., 2004). The final measurement of the TRIS values was based on the method described by Cline (1969). Similarly, samples were also collected from cylindrical corers for the measurement of the Particulate Organic Carbon (POC), organic matter (measured by Loss On Ignition), chloroplast pigments concentrations (chlorophyll-a and phaeopigments) and for the sediment's granulometry (for the latter, the sampling depth was five centimeters in order for the results to be comparable with previously published data on the study area). Also, three replicate water samples were collected by means of Niskin bottles (5 lt) which were subsequently used for the measurement of chemical variables (concentration of POC, chloroplast pigments and nutrients (phosphate ion (PO43-), nitrate ion (NO3-), nitrite ion (NO2-), ammonium ion (NH4+) and silicon dioxide (SiO2)). The aforementioned samples were processed at the Chemistry Lab of the IMBBC (HCMR), based on standard techniques (chloroplast pigments: Yentsch and Menzel, 1963; POC: Hedges and Stern, 1984; granulometry: Gray and Elliott, 2009; organic matter: Loh et al., 2008; nutrients: Grasshoff et al., 1983; Parsons et al., 1984; Strickland and Parsons, 1972).

Method steps

1. Replicates were collected at two stations, one inside and one outside the lagoon, in each lagoon (five totally), using a box corer (0.03 m2 sampling surface). The samples were sieved through a 0.5 mm mesh sieve, stained with Rose Bengal and preserved in 4% formalin. All benthic organisms were sorted in the lab and identified and counted using stereo- and microscopes. For each wetland a seperated xls file with the relevant information was prepared (both occurence and environmental data).

Main categories are: Polychaeta, Crustacea, Bivalvia

1. Polychaeta
   rank: class
2. Crustacea
   rank: subphylum
3. Bivalvia
   rank: class

Five lagoons were studied (Logarou, Tsoukalio, Tsopeli, Rodia, Mazoma)