Dose-response experiments using 5 different sediment concentrations of fluoranthene (Flu) and pyrene (Py) respectively. Measuring radioactive marked Flu and Py in brittlestars and polychaetes and microbial degradation of Flu and Py in sediment. Also growth rate of brittlestars and polychaetes and determination of regenerationtime of brittlestar-arms.
Amphiura filiformis, Nereis diversicolor, arm-regeneration, sedimentanalyses
Sediments and Amphiura filiformis from GullmarsFjord at 40m depth were collected. The sediment cores were separated into an oxic and an anoxic layer. The anoxic sediment was stored under anoxic conditions until the start of the fluoranthene(Flu)-kinetic and pyrene(Py)-microbial experiments (see below). A.filiformis was sieved from the oxic sediment and kept on sieved sediment in a flow-through system until further use. Two dose-response experiments using 5 different sediment concentrations of Flu and Py, respectively, were started on the 22nd of March. We had 4 replicate plastic buckets with added spiked sediment for each concentration and toxicant (i.e. 40 buckets with spiked sediment plus 4 control buckets in all). Sediments were spiked with freeze-dried algae (24h) and either Flu or Py (24h) at 5 different concentrations (12.5, 25, 50, 100, 300 microg/g dw sed.) before being added to the buckets. Subsequently, the buckets were randomly set up in a flow-through system with running seawater (ca.32 PSU, 4degr.celcius). The buckets were allowed to stand with running seawater for 24h before brittle stars were added. One arm per brittle star was cut off 1d before addition to the buckets (N=2 per bucket) to allow regeneration rates to be measured. Nereis diversicolor were collected from a tidal flat, and separated into boxes (3-5 body size classes) with added oxic sediment and flow-through water (ca4 degr.celsius) until the beginning of the Py-microbial experiment. both experiments were subdivided into two organic treatments; one in which sediment was spiked with easily digestible organic matter (algae paste) and one with refractory organic matter (lignin). The TOC content was equal between organic treatments. Oxic sediment was spiked with either algae paste or lignin for 24h. Subsequently, the two types of organic sediment were spiked (24h) with either 1:Py (30microg/g) alone 2:Py (30microg/g)+C14-Py or 3: Flu (30microg/g+C14-Flu). Radioactively marked Py and Flu were used as tracers. Sediments spiked with lignin or algae paste but without toxicants were used as control treatments. Relation between wet weight and dry weight of A.filiformis and N.diversicolor were determined. Methods used to sample from anoxic, bulk and burrow sediments were tested.Sediment sampling (borrow and bulk sediment) was conducted, and sediments were frozen(-20 degr.celcius) for later toxicant analysis. Subsequently, A.filiformis were sieved from the buckets, video taped (to determine regeneration rate) and frozen (-20 degr) until further analysis.