Dimethyl Sulfide is released when zooplankton and shrimp type crustaceans eat phytoplankton and algae. As it travels up in the atmosphere, it acts as a sulfur nuclei for cloud formation, cooling the waters and slowing algae growth, reducing the subsequent formation of DMS, allowing more sun to heat the water, and again spur algae growth. It's a "negative feedback loop", purported to keep the climate in homeostasis and from warming. It's called the CLAW Hypothesis. This is great for the earth, but for fishermen and other predators it signifies where the food web is most active and is the scent associated with EATING.
Schematic diagram of the CLAW hypothesis (Charlson et al., 1987)
Marine bacteria produce an environmentally important molecule with links to climate
Enhanced marine sulphur emissions offset global warming and impact rainfall