Benthic Ecology Research Programme

Bermuda has historically disposed of waste such as trash from homes and businesses by burying it in a landfill.  However, the landfill was nearly full by the late 1980's and there was no room to expand it.  No one on this small crowded island wanted to provide the land for another landfill.  The government decided that the best solution was to burn the waste in an incinerator on the North Shore of the island.  The heat from the incinerator was to be used to generate electricity by heating water and then converting the heat energy to electricity.  However no such conversion is perfect and the hot water had to be put somewhere.  Because the water comes from the ocean, the only place to dispose of it was back into the ocean.  Naturally, there was concern that the plants and animals living near the end of the pipe would be affected!  As a result, the government decided to conduct a time-series monitoring of the biological communities to see if there were any changes.  You can see a description of the outfall, the warm water plume and the nearby seagrass and coral communities below. 


In 1994 the Tynes Bay mass-burn incinerator went into operation.  From 1991 to 1994 (pre-operation) and from 1994 to 1997 (post start-up), the Benthic Ecology Research Programme (BERP) team studied the environmental impact of the hot water waste produced by the incinerator on the North Shore seagrass community.  Survey work was carried out at various long-term study sites with more intensive work conducted within the one hectare "mixing zone" immediately surrounding the end of the pipe.  Researchers examined how fast the seagrass grows and how many leaves there are in a square meter, as well as the numbers of other common constituents of the seagrass beds (fleshy and calcareous algae, sponges and tunicates). This was achieved with manual counts within permanent quadrats as well as the use of underwater video and still photography


You can see in this photo the long, thin blades of the turtle grass (Thalassia testudinum) as well as some green algae such as Neptune's shaving brush (Penicillus capitatum) which is the plant with the flat top and Halimeda, which is the round topped plant.

In addition to monitoring the biological community, researchers also conducted a study of the variation in water temperature to see what happens to the warm water plume formed by the wastewater that is discharged from the outfall.  They placed submersible electronic thermometers at 1, 3 and 6 m depths in three vertical arrays spaced 10 m apart in the area of the plume.  They recorded the ambient temperature about every 15 minutes. This vertical grid of temperature sensors indicated that the warm water floats to the surface and does not mix down as only very slight temperature increases were observed infrequently at the 3 m depths.  This means that the hot water doesn't reach the communities living nearby on the bottom.