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Michelle's Oyster Weather Indicators

Early warning for harmful algal blooms & red tides in South African shellfish waters — from satellite chlorophyll & sea-temperature data.

Overall: Watch

Keep an eye on the water

Chlorophyll slightly elevated. Keep an eye on the trend. 1 site showing rising algae.

Latest cloud-free chlorophyll pass: 16 Jun · 16 days old (satellite lag / cloud cover) · Sea temp, waves & tide are live

Read this first. The near-real-time chlorophyll feed usually runs about two weeks behind (satellite lag plus winter cloud cover), so this is a trend & early-warning tool — not a live “today” reading. Each site shows its satellite pass date and greys out when stale. For same-day confirmation before harvesting, the OCIMS red-tide tool is the authoritative check.

St Helena Bay

West Coast

Watch

Classic Benguela red-tide zone — frequent blooms & rock-lobster walkouts.

Chlorophyll-a (algae)
3.4mg/m³
steady
~6-week trend

Chlorophyll slightly elevated. Keep an eye on the trend.

🌡 Sea temp: 13.4°C 🌊 Waves: 1.4 m🌙 Tide: -0.2 m rising ▲ · High 4 PM · Low 11 PM🛰 Algae pass: 16 Jun (16d ago)

Saldanha Bay

West Coast

Safe

South Africa's main oyster & mussel farming bay.

Chlorophyll-a (algae)
2.8mg/m³
steady
~6-week trend

Algae low and stable. Good conditions for harvesting.

🌡 Sea temp: 13.8°C 🌊 Waves: 1.9 m🌙 Tide: -0.2 m rising ▲ · High 4 PM · Low 11 PM🛰 Algae pass: 16 Jun (16d ago)

Knysna

Garden Route

Safe

Home of the famous Knysna oyster.

Chlorophyll-a (algae)
2.4mg/m³
rising+81% vs baseline
~6-week trend
⚠ Algae is rising here — watch closely for a developing bloom.

Algae low and stable. Good conditions for harvesting.

🌡 Sea temp: 16.7°C 🌊 Waves: 3.3 m🌙 Tide: -0.1 m rising ▲ · High 5 PM · Low 11 PM🛰 Algae pass: 16 Jun (16d ago)

Algoa Bay (Gqeberha)

Eastern Cape

Safe

Aquaculture Development Zone — mussels & oysters.

Chlorophyll-a (algae)
1.3mg/m³
falling-30% vs baseline
~6-week trend

Algae low and stable. Good conditions for harvesting.

🌡 Sea temp: 17.2°C 🌊 Waves: 3.2 m🌙 Tide: 0.0 m rising ▲ · High 5 PM · Low 11 PM🛰 Algae pass: 16 Jun (16d ago)

How to read this

Chlorophyll-a is the amount of algae in the water, measured from space by satellite ocean-colour sensors. When it climbs — and especially when it climbs fast— a phytoplankton bloom is building. Some of those blooms are toxic “red tides” that make oysters, mussels and other filter-feeders unsafe to eat until the toxins clear.

Safe · under 3 mg/m³
Normal — water's clear. Good to harvest.
Watch · 3–8 mg/m³
Slightly up. Keep an eye on the trend.
Warning · 8–20 mg/m³
Bloom likely building. Watch closely, and check advisories before eating shellfish.
Red-Tide Risk · over 20 mg/m³
Find another supplier. Biotoxins may be unsafe — don't harvest without a lab clearance.

A rapid rise (currently +50% over baseline) bumps the alert up a level even before the water is technically “high” — the goal is to catch a bloom while it's still building. These ranges are adjustable on the settings page.

Before you harvest — check the officials

This dashboard is an early-warning screen, not a food-safety clearance. For South African waters, confirm against the authoritative red-tide & biotoxin monitoring:

OCIMS Red-Tide (HAB) Tool ↗DFFE (Forestry, Fisheries & Environment) ↗