Why sea snails struggle to reset after ocean acidification

A hidden strain under the waves

What happens inside a sea snail when ocean water turns sour? As rising carbon dioxide drives ocean acidification, marine life faces tough challenges. Scientists tested how one large sea snail, the whelk Brunneifusus ternatanus, copes when water turns acidic. They also tested whether the snails can bounce back once conditions improve.

Inside the damaged cells

The team placed snails in acidified tanks for 14 or 28 days, followed by time in clean water. To track damage step by step, they looked at the hepatopancreas, an organ combining liver and pancreas roles. This organ matters because it processes food and manages energy reserves.

Acidic water took a heavy toll on these organs. Snails lost hemocytes, which are immune blood cells that protect invertebrates from illness. Inside individual cells, rough endoplasmic reticulum sheets—folded structures that build vital proteins—began to tear. Cell outlines also became fuzzy and warped as the days went by.

The team used transcriptomics, the study of active gene messages, to observe cellular work. This test showed deep trade-offs. At 14 days, the snails cut back on power production and mitochondrial activity. By day 28, they switched on emergency immune and fuel pathways. The snails survived by rationing fuel, steering energy away from routine upkeep to fight acidic stress.

Why healing falls short

When the whelks returned to clean water, relief was incomplete. The snails showed limited healing. Fluid still pooled inside cells as oedema, an abnormal swelling of tissues, and cell edges stayed distorted. In addition, their integrated biomarker response index—a single combined score of bodily stress—remained higher than in healthy controls.

What we still do not know

This test looked at only one species over set 14-day and 28-day spans. We still do not know if more time would let stress scores fall to normal. Scientists also need to learn how these lingering debts affect snail growth, survival, and breeding in the wild.