Island trapped waves as a driver of primary production - ISLAND

 

 

 

Project leader: dr. Zrinka Ljubešić, assoc. prof.
Duration:1/2/21 - 31/1/25
Funds: 1.247.500,00 HRK
Project number: IP-2020-02-9524 

Island-trapped waves (ITWs) are a special case of coastal-trapped waves (CTWs); a well-known oceanographic phenomenon. Vertical pycnocline movements related to CTWs impact vertical mixing, transport of nutrients and primary production. We hypothesize that ITWs fuel up the primary production in the stratification period in the oligotrophic waters of Lastovo archipelago. To test this hypothesis we propose an interdisciplinary research program, that will provide insights into the physical-biological coupling on much finer scale than achieved before; using biogeochemical sensors mounted to steep underwater cliffs of the island (chlorophyll a, turbidity, photosynthetic active radiation – PAR and nutrients (nitrate and phosphate)) in addition to hydrographic sensors and a moored WireWalker - buoyant instrument platform clipped to a wire profiling from surface buoy to near the seafloor, equipped with various oceanographic sensors. In support of the high-resolution moored measurements, discrete ship-based sampling for nutrients, primary and secondary producers will also be performed, as well as continues analyses state of the benthic community using photographic quadrants. Primary productivity will be assessed from diel cycles in bio-optical properties both from the Wirewalker, as well as from ship based measurements during the stratification and period of water column mixing. Observations that elucidate primary production dynamics will be augmented by high resolution records of temperature, light intensity, chlorophyll a and nutrients from sensors. To determine the primary and secondary producers multiple tools will be used (light and electron microscopy, flow-cytometry, DNA High-throughput sequencing). Through this comprehensive suite of measurements, we anticipate development of a concrete linkage between the physical dynamics and nutrient enhancement in the sunlit portion of the water column that fuel primary production, as well as to the benthic community, which can be associated with mass mortality events.