Plans to remove 15,000 cubic metres of shingle from Shoreham Beach have sparked fury because of the area's reputation for rare and endangered plants.
Council bosses have approved the operation despite earlier lambasting heavyweight boxer Scott Welch for shifting a small amount of the shingle to build a swimming pool.
Officers acknowledge residents are upset about losing "half their beach" but say the work will not effect shrubs and is vital to the region's coastal defences.
Protesters are organising a public meeting and petition to get the plan axed before the diggers move in this autumn.
David Wood, vice chairman of The Shoreham Society, said: "The shingle beach is a quiet natural area enjoyed by both visitors and residents.
"The flowers aren't just colourful, they are indicators of stability. A lot hangs on that stability.
"This vegetation depends on forward protection against waves.
"We need every pebble in the beach for coastal protection and as a recreation area for our increasing local population. Adur District Council cannot be serious about giving it away."
The Port Authority will use the pebbles to bolster sea defences in Southwick.
The scheme has already been sanctioned by the Environment Agency and the council.
The shingle will be taken from a 450-metre stretch of beach starting at the harbour wall, 60 metres from the residential boundaries, to the foreshore.
It will be moved by lorry via Harbour Way to the A259 to Southwick over five weeks.
Mr Wood said: "How many lorry loads is that going to be? What effect will it have in terms of vibration and road damage. Who is going to pay for it?
"If this is the best the council can do I think it is time for a change in procedure. How is anyone supposed to know what the ground rules are?"
A spokesman for Adur District Council said: "We have an obligation to protect all the coastline. The whole coast suffers from lateral drift from west to east, which is why so much shingle ends up on the Shoreham peninsular.
"Not all that shingle is needed there, but it is needed in Southwick.
"The shingle at Shoreham will replenish itself within a year and more will be removed to where it is needed.
"Moving it around like this is the most environmentally-friendly way of doing it.
"We don't do this lightly. The area does have some rare vegetated shingle plants, but if we leave the extra shingle, that too could cause problems.
"There is a powerful body of experts saying we should do this, including English Nature and the Environment Agency.
"We realise a lot of residents will sign the petition and we will look at it sympathetically but we have to look at the wider picture."
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