Long-term survival of marine planktonic diatoms and dinofiagellates in stored sediment samples

Abstract

Sediment samples from Scottish coastal sites, taken over the last 9 years, were stored in closed containers at 5°C. Slurry cultures were used to determine the survival of phytoplankton in these sediments. A range of diatom and dinoflagellate species survived for at least 27 months in these stored samples. A number of species grew for which no resting stage has yet been described: Thalassiosira angulata, T. pacifica, T. punctigera, T. eccentrica, T. minima and T. anguste-lineata. Notable results were survival times of 73 months for Skeletonema costatum, 96 months for Chaetoceros socialis, C. didymus and C. diadema, 109 months for Scrippsieila sp. and 112 months for Lingulodinium polyedrum. A single sample was stored and repeatedly cultured for diatoms over a period of 16 months. The number of species cultured from the sediment declined over this time. Lingulodinium polyedrum cysts isolated from sediments collected at least 18 months previously gave a hatching success of 97% and cysts isolated from a 9-year-old sample gave a hatching success of 3%. The study indicates the potential importance of coastal sediments as a source of phytoplankton to their overlying waters. The validity of using marine planktonic diatoms and dinoflagellates for modelling geological events is discussed.