Red tide on Amelia Island

The record, site by site

Days ahead of print. A map is data, not a published reading. Every local sample appears here the day it lands, and stays long after the map drops it.

Kept by justaskamelia.com

• not present
• very low
• low
• medium
• high

Every reading here is documented. The older ones are transcribed from the state's own Friday reports. The newer ones are read off the map the day they appear. Sites run nearest first, measured from Main Beach, and each reading carries the gap between the day it was collected and the day it reached print. What the bands mean is further down.

What red tide actually is

Red tide is a bloom of Karenia brevis, a single-celled alga that lives in the Gulf of Mexico and occasionally drifts around the state. It has nothing to do with the tide. Tides are the daily rise and fall of the sea caused by the moon; the two share a word and nothing else.

It is overwhelmingly a southwest Florida problem. Our stretch of the Atlantic coast gets it rarely, which is exactly why it is worth knowing when samples do turn up here rather than assuming they never will.

What the levels mean

Florida Fish and Wildlife reports concentrations in cells per liter, in named bands. The reading above uses these words, so this is how to translate it.

Is it safe to swim?

Florida Fish and Wildlife's advice is plain: do not swim in or around red tide. They list skin irritation, rashes, and burning or sore eyes. Much of the effect on people is also airborne, because broken cells release brevetoxin into the sea spray, so an onshore wind and heavy surf make it noticeably worse than a calm day at the same concentration.

The usual effect on a healthy person is respiratory irritation, meaning coughing, sneezing, a scratchy throat and itchy eyes, which clears up after leaving the beach. If you have asthma or another respiratory condition, take it seriously and check before you go.

One thing worth knowing: at low and very low concentrations the water does not look any different. There is no discoloration to watch for, which is why the sampling numbers matter.

Beach swim advisories, which are about bacteria rather than red tide, are issued separately by the Florida Department of Health. Those are on our Today on the Island page.

Shellfish, and the mistake that matters

Florida closes shellfish harvesting areas when concentrations pass 5,000 cells per liter. Closures are decided by the Department of Agriculture and posted daily at shellfish.fdacs.gov, which is the authority on whether a specific area is open. Where we are carrying a current closure near the island, it appears in the live reading at the top of this page, with the date it was checked.

Separately, the harvest of wild oysters is closed statewide from July 1 to September 30 every year for reasons that have nothing to do with red tide, so during those months an open or closed status applies to aquaculture leases and wild clam harvest.

Check it yourself

Everything above is read from public sources, and you can read the same ones.

• FWC's live sampling map. Updated daily at 5 p.m. Every dot is clickable for its date, depth and concentration.
• FWC's written status report. Published Friday afternoons. Note that it is a weekly summary, so between Fridays the map is ahead of it.
• FDACS shellfish harvesting area status. Daily open and closed status by area.
• Florida's red tide hotline, (866) 300-9399, a recorded statewide update any time.