Variability in sediment and mussel-associated algal biomass along a depth gradient in Lake Ontario

Session: Mud, Macrofauna and Microbes: Benthic Organism-Abiotic Interactions at Varying Scales (2)

Leon Katona, Wright State University , [email protected]
Knut Mehler, Great Lakes Center at SUNY Buffalo State, [email protected]
Lyubov Burlakova, Great Lakes Center at SUNY Buffalo State , [email protected]
Alexander Karatayev, Great Lakes Center at SUNY Buffalo State, [email protected]
Yvonne Vadeboncoeur, Wright State University, [email protected]

Abstract

Sediment alteration by dreissenid mussels impact Great Lakes zoobenthos, but there is little information on how these changes affect algae growing on soft sediments within the euphotic zone. We measured chlorophyll extracted from soft sediments (45 sites) and attached to dreissenid mussel shells (32 sites) from depths of 8 – 212 m in Lake Ontario in September 2018. We used a Pulse Amplitude Modulated fluorometer to assess variation in benthic photosynthesis on collected sediments. Photosynthesis, chlorophyll extracted from sediments and chlorophyll attached to mussel shells declined linearly with depth, likely due to light attenuation in the water column. Chlorophyll was greatest at depths less than 50 m and there were similar amounts of chlorophyll attached to mussel shells and in sediments. At depths greater than 50 m, a standing stock of approximately 5 mg chlorophyll per m² persisted in the sediment and mussel shells had little attached chlorophyll. Microscopic examination revealed mobile benthic diatoms in sediment samples and filamentous algae (Cladophora), diatoms and green algae attached to mussel shells collected from shallow depths. By creating patches of hard substrate and increasing water clarity, dreissenid mussels increase benthic chlorophyll and change the assemblages of attached algae in littoral Lake Ontario.

Twitter handle of presenter
lekatona