I recently read an article on the weed problem - sea lettuce. I was impressed by how many authorities were actively monitoring the situation, but one glaring omission stood out.

Although there was the usual blurb, ranging from agricultural run-off to seasonal weather patterns, nothing was mentioned of possibly the greatest contributors to this scourge.

Sea lettuce has its natural place in the harbour, but the volume during recent years has burgeoned to plague proportions.

I'm convinced mismanagement and complacency has seen this once pristine harbour descend to the cesspool we see today.

Culprit one: Allowing commercial fishing of parore, grey mullet and flounder in inland waterways. Parore eat the weed, grey mullet eat the faeces (often directly from the host's anus), crabs clean up the mullet faeces and flounder thrive on crabs.
Shrimps ensure nothing is left behind the crabs. It's called a food chain and the primary links have been broken.

Culprit two: black swans and Canadian geese. These birds contribute more to the problem than any other source.

An adult bird can eat or destroy its own body weight of marine habitat and juvenile fish every 24 hours. Tens of thousands descend on Tauranga Harbour every season.
After grazing damage comes the resultant effluent, smothering the harbour's seabed for hectares around their activities.

As with most inland harbours, Tauranga cannot completely flush with tidal movements so the nutrients from swan and geese faeces simply spreads, creating ideal conditions for sea lettuce to thrive. These birds are not native and contribute nothing to our ecosystem. Total eradication would be a great start to recovery of the jewel in the crown of Tauranga.

Kevin Molloy, Omokoroa.