Imaging FlowCytobot, Profiling Sonde Data, and Targeted Nutrient and Carbonate Measurements from a 2024 Dinophysis acuminata Bloom in Salt Pond, Eastham, MA

This dataset consists of physical, chemical, and biological time series observations collected throughout the course of a dense Dinophysis acuminata bloom in Salt Pond, Eastham, MA during the summer of 2024. The Imaging FlowCytobot dataset comprises images of nano- and micro-plankton triggered by particle scatter. The sonde data includes continuously-measured depth-resolved temperature, conductivity, dissolved oxygen, PAR, and fluorescence (chlorophyll and phycoerythrin). This dataset also includes discrete, targeted measurements of nutrients (ammonium, total oxidized nitrogen, phosphate, silicate) and carbonate measurements (dissolved inorganic carbon, pH, total alkalinity) at several time points throughout the bloom.

Data Description: Particle images, sonde data, and discrete nutrient and carbonate measurements. The images are generated by the Imaging FlowCytobot (IFCB), which takes images of nano-and micro-plankton triggered by particle scatter. IFCB data are stored in .zip files with the date time encoded in the filename (see README). Within each .zip file, there are three files per sample. The .hdr files contain sample metadata, including field names for the .adc file. The .adc file contains flow cytometric data from each image, including particle scatter parameters. The .roi file contains all the images associated with that sample. The sonde data (2024_rosbag_downcasts.csv) are collected by an AML Oceanographic CTD and consist of just downcasts of depth, temperature, conductivity, dissolved oxygen, PAR, and fluorescence (chlorophyll and phycoerythrin) from before through the end of the study period. The discrete nutrient measurements (SaltPond_Discrete_Nutrient_Data_data_export.xlsx) consist of ammonium, total oxidized nitrogen, phosphate, and silicate, and the discrete carbonate measurements (pH_Nauset_Summer_data_export.xlsx) consist of pH, dissolved inorganic carbon, and total alkalinity measurements.

Acquisition Description: The Salt Pond observatory float consisted of an IFCB, an AML-6 sonde (AML Oceanographic, Victoria, BC, Canada), and a pair of winches that dynamically controlled both sonde profiling and depth of IFCB and water chemistry sample collections. The sonde was secured near the bottom of the IFCB so that it recorded relatively undisturbed water during downcasts of the combined IFCB-sonde unit. Additionally, the IFCB sample intake was extended so that it drew its samples immediately adjacent to the sonde’s main array of sensors. Profiling of these sensors was controlled using a robot operating system (ROS) based middleware architecture called PhytO-ARM (https://github.com/WHOIGit/PhytO-ARM). The system was programmed so that a hydrographic profile from 1 to 6.5 meters was collected by dropping the IFCB-sonde package at a rate (~2 cm s-1) prior collection of each IFCB sample. The IFCB was then positioned at the depth of maximum observed phycoerythrin fluorescence or a pre-programmed depth (1, 2.25, 3.5, 4.75, or 6 m), then triggered to collect and analyze a 5 mL seawater sample, so that both a sonde profile and IFCB sample were collected approximately every 25 minutes. IFCB image collection was configured to target red fluorescent particles (excitation/emission wavelengths: 635/680nm) so that records were not overwhelmed by high loads of non-fluorescent detritus. To collect targeted measurements of nutrients and pH, a peristaltic pump with inline 0.45µm and 0.2µm capsule filters in sequence was connected to plastic tubing on the platform’s secondary winch; sampling occurred at slack high tide in increments of 0.25 m from 0.5 m below to 0.5 above the position of the phycoerythrin maximum. Nutrient samples were frozen at -20˚C until analysis; carbonate samples were poisoned with mercuric chloride to 0.04% v/v and sealed with an air-tight cap before analysis.