One of the most highly affected victims of dead zones is the Baltic sea. This practically isolated bay is located in north-western Europe, surrounded by Sweden, Finland, Russia, Estonia, and other Scandinavian countries. The Save Our Baltic Sea Organization writes, "According to the World Wildlife Fund, seven of the ten world's largest marine dead zones are located in the Baltic Sea" (Save Our Baltic Sea Organization)¹³. It is an area that truly exemplifies the issues of hypoxia.
Like with all dead zones, the Baltic Sea’s issue starts with the use of synthetic, often nitrogen-based fertilizer in farms of the same watershed (Ecopol). The chemicals that help farmers grow crops also cause a growth in algae blooms, leading to a rapid overuse of oxygen (Teach Ocean Science)⁶. The environment left behind does not have enough oxygen to support the sea life, potentially causing the ecosystem to collapse (Virginia Institute of Marine Science)⁸.
When the habitat of the sea suffers, the ecology becomes less diverse. Not only do the blooms of algae cause hypoxia, they also block sunlight. If the base of the food chain, seaweed, is unable to photosynthesize, it dies, leaving a loss of food and habitat for fish in the ecosystem (Calacademy)⁴.
Furthermore, dead zones literally cause aquatic species to suffocate. Ecosystems can also be affected when animals like crabs migrate out of hypoxic areas (Tech Ocean Science)⁶. According to the Virginia Institute of Marine Science, even slight oxygen loss is a large problem (Virginia Institute of Marine Science)⁸. Marine animals have to use a lot of energy to obtain the resource because water has a lower density of oxygen (Virginia Institute of Marine Science)⁸. This issue amplifies the impact of ocean dead zones significantly.
Global climate change is also worsening the frequency of dead zones (Kasper)
Oceans Monthly/June, 2014 6
frequency of dead zones (Kasper)¹¹. And with 95% of marine animals needing adequate dissolved oxygen (Kasper)¹¹, this will threaten biodiversity greatly. To get the oxygen they need, fish and other organisms are now living closer to the surface of the water, which puts them at risk for predators. This increased surface density also makes population seem inflated.
But why does it matter?
There are many reasons why such an issue matters both biologically and economically. When the habitat of the sea suffers, the