Milbrandt, E. | bioRxiv Science

bioRxiv2018

Harmful algae bloom monitoring via a sustainable, sail-powered mobile platform for in-land and coastal monitoring

Harmful algae blooms (HAB) in coastal marine environments are increasing in number and duration, pressuring local resource managers to implement mitigation solutions to protect human and ecosystem health. However, insufficient spatial and temporal observations create uninformed management decisions. In order to better detect and map blooms, as well as the environmental conditions responsible for their formation, long-term, unattended observation platforms are desired. In this article, we describe a new cost-efficient, autonomous, mobile platform capable of accepting several sensors that can be used to monitor harmful algae blooms in near real-time. The Navocean autonomous sail-powered surface vehicle is deployable by a single person from shore, capable of waypoint navigation in shallow and deep waters, and powered completely by renewable energy. We present results from three surveys of the Florida Red Tide harmful algae bloom (Karenia brevis) of 2017-2018. The vessel made significant progress towards waypoints regardless of wind conditions while underway chl. a measurements revealed HAB bloom patches and CDOM and turbidity provided environmental contextual information. While the autonomous sailboat directly adds to our HAB monitoring capabilities, the boat can also help to ground-truth and thus improve satellite monitoring of HABs. Finally, several other pending and future use cases for coastal and inland monitoring are discussed. To our knowledge, this is the first demonstration of a sail-driven vessel used for coastal HAB monitoring.

ecology↗

bioRxiv2017

From lake to estuary, the tale of two waters. A study of aquatic continuum biogeochemistry

The balance of fresh and saline water is essential to estuarine ecosystem function. Along the fresh-brackish-saline water gradient within the C-43 canal/Caloosahatchee River estuary (CRE) the quantity, timing and distribution of water and associated water quality significantly influences ecosystem function. Long-term trends of water quality and quantity were assessed from Lake Okeechobee to the CRE between May 1978 to April 2016. Significant changes to monthly flow volumes were detected between the lake and the estuary which correspond to changes in upstream management. and climatic events. Across the 37-year period total phosphorus (TP) flow-weighted mean (FWM) concentration significantly increased at the lake, meanwhile total nitrogen (TN) FMW concentrations significantly declined at both the lake and estuary headwaters. Between May 1999 and April 2016, TN, TP and total organic carbon (TOC), ortho-P and ammonium conditions were assessed within the estuary at several monitoring locations. Generally nutrient concentrations decreased from upstream to downstream with shifts in TN:TP from values >20 in the freshwater portion, ~20 in the estuarine portion and <20 in the marine portion indicating a spatial shift in nutrient limitations along the continuum. Aquatic productivity analysis suggests that the estuary is net heterotrophic with productivity being negatively influenced by TP, TN and TOC likely due to a combination of effects including shading by high color dissolved organic matter. We conclude that rainfall patterns, land use and the resulting discharges of run-off drives the ecology of the C-43/CRE aquatic continuum and associated biogeochemistry rather than water management associated with Lake Okeechobee.

ecology↗