Environment Minister Mark H Durkan has been urged to include waters around Islandmagee, Co Antrim in a planned network of protected marine areas.
Islandmagee Community Residents Association has warned that the rich waters could be under threat from plans for a gas power station, which would pump brine into the sea.
The brine, created by dissolving salt reserves to create underground salt caverns, could create a 'dead zone' in the North Channel, the group said.
"Gaelectric propose to build a gas power station in Islandmagee.
"However, this requires the creation of large salt caverns, the contents of which will be pumped into our delicate and biodiverse sea," the group said in a letter which is being submitted in response to a planning application."
The group said the site of the power station is next to a site that was overlooked in recently proposed Marine Protection Zones, even though it is home to black guillemots, kittiwake, fulmar, razorbill and Northern Ireland's only onshore colony of breeding puffins, a species that is declining.
The Department of the Environment said it had confirmed in July last year that the application, if carried out, would be of Regional Significance and any decision would be taken by the minister.
"The department has been engaging with the company in pre-application discussions around all the terrestrial and marine issues that arise from a proposal of this nature."
Gaelectric said that its Environmental Statement (ES) for the project addresses the marine flora and fauna impacts under a worst case scenario and concludes that the significance of the brine impact is considered low.