Transport of microbial biomass through the North Inlet ecosystem

Area of Science:

• Marine Biology
• Estuarine Ecology
• Biogeochemistry

Background:

• Estuarine ecosystems are vital interfaces for nutrient and biomass exchange.
• Understanding microbial biomass dynamics is crucial for estuarine health.
• Tidal forces significantly influence material transport in coastal areas.

Purpose of the Study:

• To investigate tidal fluctuations and transports of microbial biomass (ATP) in North Inlet marsh creeks.
• To compare seasonal and tidal influences on biomass exchange between marsh and adjacent aquatic ecosystems.
• To quantify net transport of microbial biomass through major marsh-ocean transfer points.

Main Methods:

• Simultaneous sampling of three marsh creeks (Town Creek, North Jones Creek, South Jones Creek) over 50-hour periods during neap and spring tides.
• Measurement of total microbial biomass using adenosine triphosphate (ATP) concentrations.
• Analysis of ATP concentration fluctuations in relation to tidal cycles and seasons.
• Calculation of net ATP transport (import/export) across tidal cycles.

Main Results:

• ATP concentrations exhibited seasonal variations, peaking in spring (2.17 mg/m³) and lowest in winter (0.65 mg/m³).
• At the inlet, ATP fluctuations were in phase with tides in winter/fall and out of phase in spring.
• South Jones Creek showed irregular ATP fluctuation patterns.
• Net ATP transports were generally small and varied in direction (import/export) between tidal cycles.

Conclusions:

• Tidal and seasonal factors significantly influence microbial biomass dynamics in marsh creeks.
• While instantaneous ATP fluxes can be large, net long-term transport between the marsh and ocean is minimal.
• Marsh-estuarine interfaces play a complex role in microbial biomass regulation.