Research Publication Title

Vertical diatom motility in relation to tide shifts on St. Simons Island, GA

Major

Biology

Faculty Mentor(s)

Dr. Kalina Manoylov

Keywords

Diatom, Movement, Tide-Shifts, Motility, Sediments, Sand-grains, Community

Abstract

Barrier islands incorporate various types of ecosystems including: open beaches, tidal ponds, mixed estuaries, and tidal marshes. Ecology of those habitats is largely unknown for the Georgia coast. Diatoms are a common algal group in sediment and beach samples and they are often used as bioindicators on species level. Diatom functional groups are based on the ability to move or attach to substrate, which can provide ecological information of great value. Biraphid diatoms, with complex slits in the silica cell wall, move to the sand surface. This movement follows exposure of the beach surface during low tide. With access to light diatoms perform photosynthesis and create a temporary biofilm that serves as an important food source for grazers. The goals of this study were first to document species composition of algae on exposed to desiccation sand at low tide. Second, to classify all diatoms based on their ability to move or attach. Third, to estimate species specific distance of movement along the known gradient. The level of movement of varying diatoms were measure by taking known height (0.5 cm, 1 cm and 2 cm). sand sample at the same time of the day during low tide using Petri dishes, resulting with 27 samples from May and June 2016. Samples were dominated by live diatoms (99%). Within the diatom community, biraphid diatoms such as representatives of the genera Nitzschia and Navicula had 50 and 25% relative abundance respectively. Chain forming marine planktonic diatoms like Cymatosira belgica Grunow (20%) were probably deposited on the surface as the ocean retreaded. Species richness was significantly different between distances for movement, but biodiversity remained high in all samples. There was a higher percentage of biraphid diatoms at 2 cm compared to 0.5 cm. Biraphid diatoms presented a higher probability for survival deeper in the sediment.

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Vertical diatom motility in relation to tide shifts on St. Simons Island, GA

Barrier islands incorporate various types of ecosystems including: open beaches, tidal ponds, mixed estuaries, and tidal marshes. Ecology of those habitats is largely unknown for the Georgia coast. Diatoms are a common algal group in sediment and beach samples and they are often used as bioindicators on species level. Diatom functional groups are based on the ability to move or attach to substrate, which can provide ecological information of great value. Biraphid diatoms, with complex slits in the silica cell wall, move to the sand surface. This movement follows exposure of the beach surface during low tide. With access to light diatoms perform photosynthesis and create a temporary biofilm that serves as an important food source for grazers. The goals of this study were first to document species composition of algae on exposed to desiccation sand at low tide. Second, to classify all diatoms based on their ability to move or attach. Third, to estimate species specific distance of movement along the known gradient. The level of movement of varying diatoms were measure by taking known height (0.5 cm, 1 cm and 2 cm). sand sample at the same time of the day during low tide using Petri dishes, resulting with 27 samples from May and June 2016. Samples were dominated by live diatoms (99%). Within the diatom community, biraphid diatoms such as representatives of the genera Nitzschia and Navicula had 50 and 25% relative abundance respectively. Chain forming marine planktonic diatoms like Cymatosira belgica Grunow (20%) were probably deposited on the surface as the ocean retreaded. Species richness was significantly different between distances for movement, but biodiversity remained high in all samples. There was a higher percentage of biraphid diatoms at 2 cm compared to 0.5 cm. Biraphid diatoms presented a higher probability for survival deeper in the sediment.