New study links red tides and dead zones off west coast of Florida

The study found that when red tides began in the summer and continued into the fall, low oxygen areas were more likely to occur. The first study to link low oxygen to red tides on the west coast of Florida is being conducted by scientists at the University of Miami.

Red tides are becoming an annual occurrence off the west coast of Florida due to massive blooms of Karenia brevis fueled in part by excess nutrients in the ocean. These blooms turn the ocean surface red and produce toxins that are harmful to marine mammals, sharks, seabirds and humans causing a range of issues from respiratory irritation to large-scale massive mortalities to marine life. Hypoxic areas are referred to as dead zones.

The disruptive events are being used in population assessments of some grouper species. About 30% of the red grouper population was killed during the red tide in 2005, according to Brendan Turley, an assistant scientist at the UM's Cooperative Institute of Marine and Atmospheric Studies.

The study looked at nearly 20 years of oceanographic data, including temperature, salinity, and dissolved oxygen from the surface to the seafloor across the West Florida Shelf to determine the occurrence of hypoxia and association with known red. The researchers found that there were five instances of hypoxia in the 16 years examined, three of which occurred at the same time as red tides. There is an ongoing effort to collaborate with commercial fishermen in Southwest Florida to monitor for red tide blooms and formation of hypoxia, which incorporates data collected during various NOAA surveys conducted in the region annually.

The study titled "Relationships between blooms of Karenia brevis and hypoxia across the West Florida Shelf" will be published in the May issue of the journal. The authors of the study are Brendan Turley, Matthew Campbell, David Hanisko, and Christopher Kelble.

More information: Brendan D Turley et al, Relationships between blooms of Karenia brevis and hypoxia across the West Florida Shelf, Harmful Algae (2022). DOI: 10.1016/j.hal.2022.102223 Citation: New study links red tides and dead zones off west coast of Florida (2022, April 26) retrieved 26 April 2022 from https://phys.org/news/2022-04-links-red-tides-dead-zones.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.