Seas are smaller than oceans and are typically partially enclosed by land. They are important for marine biodiversity, human activities, and have unique characteristics depending on their location and environment.
Seas in India
1. Arabian Sea
The Arabian Sea is part of the northern Indian Ocean, bounded by the Indian subcontinent to the east, the Arabian Peninsula to the west, and the Horn of Africa to the south.
Example:
- The coast of Gujarat, Maharashtra, Karnataka, Kerala, and Goa in India.
Composition:
- Water Salinity: Around 35-37 PSU (Practical Salinity Units).
- Dissolved Gases: High levels of dissolved oxygen and carbon dioxide.
- Nutrients: Rich in nutrients like nitrates and phosphates due to upwelling, supporting a diverse marine ecosystem including fish, corals, and plankton.
- Minerals: Sediments containing silt, clay, and sometimes oil and natural gas reserves.
- Biodiversity: Home to diverse marine life including dolphins, whales, and various fish species like tuna and mackerel.
2. Bay of Bengal
The Bay of Bengal is the northeastern part of the Indian Ocean, bordered by India and Sri Lanka to the west, Bangladesh to the north, and Myanmar and the Andaman and Nicobar Islands to the east.
Example:
- The coasts of Tamil Nadu, Andhra Pradesh, Odisha, and West Bengal in India.
Composition:
- Water Salinity: Varies from 32 to 34 PSU, influenced by freshwater input from major rivers like the Ganges, Brahmaputra, and Mahanadi.
- Dissolved Gases: Similar to the Arabian Sea, with significant levels of dissolved oxygen and carbon dioxide.
- Nutrients: High nutrient content due to river runoff, supporting abundant phytoplankton growth and a rich fishery.
- Minerals: Sediments rich in organic matter, silt, and clay.
- Biodiversity: Hosts numerous species of fish, sea turtles, and marine mammals. The Sundarbans, a large mangrove forest, is located at the mouth of the Ganges.
Seas Around the World
1. Mediterranean Sea
The Mediterranean Sea is almost completely enclosed by southern Europe, northern Africa, and western Asia.
Example:
- The coast of Italy, Greece, Turkey, and Egypt.
Composition:
- Water Salinity: Higher than the average ocean salinity, around 38-39 PSU, due to high evaporation and limited freshwater input.
- Dissolved Gases: Varies, with oxygen levels influenced by water temperature and depth.
- Nutrients: Relatively low in nutrients compared to other seas, leading to oligotrophic conditions, but nutrient levels are higher in regions with river inflow.
- Minerals: Contains sediments from river runoff, rich in calcium carbonate.
- Biodiversity: Diverse marine life including the endangered Mediterranean monk seal, various species of fish, and sea turtles.
2. Caribbean Sea
The Caribbean Sea is a tropical sea, part of the Atlantic Ocean, bounded by Central and South America and the islands of the Caribbean.
Example:
- The coasts of Jamaica, Cuba, and the Yucatan Peninsula in Mexico.
Composition:
- Water Salinity: Around 35 PSU.
- Dissolved Gases: High levels of dissolved oxygen due to warm temperatures promoting high biological activity.
- Nutrients: Varies, with some areas having nutrient-rich waters supporting coral reefs.
- Minerals: Calcium carbonate sediments from coral reefs and limestone formations.
- Biodiversity: One of the most biodiverse marine regions, with extensive coral reefs, mangroves, and seagrass beds. Home to numerous fish species, marine mammals, and sea turtles.
3. Baltic Sea
The Baltic Sea is a brackish inland sea, enclosed by Scandinavia, the Baltic countries, and the North European Plain.
Example:
- The coast of Sweden, Finland, and Estonia.
Composition:
- Water Salinity: Low salinity, ranging from 0 to 8 PSU, due to significant freshwater input from rivers.
- Dissolved Gases: Variable, with potential for low oxygen zones (hypoxia) due to limited water exchange with the North Sea.
- Nutrients: High nutrient levels from agricultural runoff, leading to eutrophication in some areas.
- Minerals: Fine sediments, including silt and clay, often impacted by human activities.
- Biodiversity: Less diverse than more saline seas, but includes species adapted to brackish conditions, such as the Baltic herring and various seabirds.
Chemical Composition of Sea Water
Sea water composition is generally similar across different seas but can vary based on local conditions such as freshwater inflows, evaporation rates, and geological features.
Key Components:
- Salts (mainly sodium chloride): Around 3.5% by weight in typical seawater, with variations in enclosed seas like the Baltic Sea.
- Dissolved gases: Oxygen, carbon dioxide, and nitrogen.
- Nutrients: Nitrates, phosphates, silicates, essential for marine life productivity.
- Trace elements: Magnesium, calcium, potassium, and other minerals.
Seas play a crucial role in the global ecosystem, supporting a wide range of biodiversity, influencing weather patterns, and providing resources for human use. Each sea has unique characteristics shaped by its location, climate, and surrounding geography.
