ALEXANDRE MONIZ BARBOSA
PANJIM: Biological oceanographer, Dr Helga do Rosario Gomes, a Research Scientist at Lamont-Doherty Earth Observatory, Columbia Climate School has said that the biodiversity of the Arabian Sea has changed completely.
Her research on the Arabian Sea has concluded that ‘the biodiversity, the biology of the Arabian Sea, especially the base of the protein, which is the plant-like structures of this Arabian Sea had changed completely’.
Having done her PhD at NIO and a lot of her thesis work in the Arabian Sea, Rosario Gomes, hailing from Goa and currently with Columbia University in New York, returned later to conduct more research on the Arabian sea.
“When we started looking at the data, we saw that there were very unusual organisms. When we asked our colleagues about them, they said they were seeing them very much. We know them as noctiluca and it’s called noctiluca scintillans. We started researching this noctiluca and we saw that there were giant massive blooms generally found only during the winter monsoon,” she told O Heraldo.
She said that when there are not many nutrients, the noctiluca are able to eat other things. “They can also eat dead material, detritus, eggs, anything that they find. What is happening is the waters are getting warmer. When the waters are getting warmer at the surface, there is this thing called stratification, which means that the bottom layers are not able to come to the top and fertilise. So, in this case, with the stratification there are no nutrients. So, on one side, they are taking whatever nutrients there are in the water and at the same time they are feeding on little, little things. Those little, little things were food for other little, little things. So, they have taken away another food source, they have taken away another nitrogen source,” said Dr Rosario Gomes.
She added too that sewage released in the waters is adding to the changes in the sea. “You also have these mega cities around the Arabian Sea and nobody has sewage treatment plants. I have read that our Goa sewage plants are working at like 20 to 40 percent of their capacity. So, imagine the amount of organic matter that we are dumping into the oceans. It’s a great environment for noctiluca, for scalps and jellyfish. So, everything is working like in their favour. Based on whatever studies we had, we know that the biodiversity of the Arabian Sea has changed drastically.”
Having also worked on climate change, she said that the rising temperatures in Goa are similar to the unstable systems everywhere in the world. “It will not be persistently heat, but very unstable systems. It’s already been predicted that we would have less rain, but then we will have incidences of very strong rainfall. We will not have persistent rainfall like how we used to have, we will have massive dry spells and then events of extreme rainfall and you've seen that already, last year I think, or the year before,” she said.
Though her area of research does not involve rising sea levels, speaking on the NASA prediction that areas of the Goa coast could go underwater by 2100, she said, “That is very concerning because that is based on the fact that warm water expands and so it rises.” Dr Rosario Gomes added, “I think one thing that will happen is that when the sea level rises, saline water will enter the rivers. Our rivers have got such amazing biodiversity, especially at the mouth. Right now if saline waters from rising sea level, and we are seeing that already, enter the mouth of the river, these delicate organisms shift. A sudden massive influx of saline water will not only impact the plankton, but impact other organisms that are on the banks, like, these tisreo, khube, all our fisheries.”
One reason for the increase in mangroves around Goa’s riverine islands could be the incursion of saline waters as mangroves can tolerate much salinity. She said, “The rivers are also no longer flowing the way they used to. There are a lot of river networks, rivulets that keep the water flow nicely and keep the ecosystem in balance. But now the ecosystem is already out of balance, both in the Arabian Sea, and in these riverine systems, especially at the mouth of the estuary. What is happening at the top and what is happening here, is going to impact the estuary. And that is where our fish is.”
She suggested that to reduce this inflow, Goa should ensure that the network of water is flowing and cautioned on the incursion of saltwater. “For saltwater to enter an estuary is, I think, nearly the death of the estuary as it is, then it just becomes an oceanic system and as salt intrusion goes up, the organisms are not able to withstand that as they are purely fresh water,” Rosario Gomes said.
The scientist also called for long term studies on understanding why these blooms are increasing in the Arabian Sea. “We know why they are happening, but often Indian scientists try to contradict us but there hasn’t really been a concerted study on why these new organisms are appearing. There is no long term study on the impact of rising sea level on this. I think we should have a network of universities, maybe of colleges, masters students in science researching on how and why is salt water intruding into our systems,” she said.