The Open Ocean

1. The Open Ocean By: Connor Mallon and Joey Mudd

2. Abiotic Factors • Temperature: The average temperature of the open ocean can vary, as cloud cover and ocean currents greatly alter it. In places like the South Pacific, it can be very warm, but in places like the North Atlantic, it can be cool. • Salinity: The average salinity of the open ocean can vary, but usually it is about a global average of 35 parts salt per thousand parts water This salinity raises the freezing point of the water, preventing it from freezing, and helps several mollusks or crustaceans by encouraging the precipitation of calcium carbonate.

3. Abiotic Factors cont. • Density: The density of the open ocean is decided by multiple factors. The temperature and salinity define how certain elements are affected, such as ice floating up due to a higher density than water. Heavier masses tend to sink to the bottom, while lighter masses sink to the top. • Water Movement: Three other factors also influence the ocean, those being wind, gravity, and the Earth’s rotation. Wind blows against the ocean, and helps move the water and influences the surface waters. Gravity causes tides and heavily influences the density flows. The Earth’s rotation makes the ocean floor move out from the water above it. These factors keep nutrients from sinking to the bottom floor.

4. Plant Adaptations • Photosynthesis: Open ocean going plants have mostly adapted to the hostile environment of the open ocean by developing gas and air sacks that lift their photosynthetic surfaces to the surface water. This is especially critical for plants that come from the deep ocean. • Ocean Salinity: Since some salty regions can be more dangerous to some plants more than others, plants have either evolved to live in non-salty regions, or have devolved complex mechanisms to break down salt into chlorine and sodium ions, or other mechanisms that store the salt and ass it onto the respiratory systems of the plants. For some regions, these plants can be vital, since they may prevent some regions from getting intolerably salty.

5. Structure • The open ocean is split into two categories, photic and aphotic. In photic zones, light penetrates through, while in aphotic zones light does not, and this entirely determines the ecology of the zone. • Photic Levels: In photic levels lights penetrates through, and the most commonly thought of zone if the Epipelagic Zone. Here light is in abundance and photosynthesis occurs, and there is an abundance of sea organisms that can live off the plants and the organisms that feed on them.

6. Structure cont. • Photic Levels: The Mesopelagic Zone is a “twilight” area where some light breaks through but it is not enough for photosynthesis, and darkness radically increases as depth increases. Many animals here either live off the detritus that falls from the Epipelagic Zone or travel up to it to feed. • Aphotic Levels: The first aphotic level is the Bathypelagic Zone. Here light doesn’t break through, and all organisms either feed on detritus or other organisms that inhabit the area. This is also the zone where temperature and pressure can become radical. Any light is solely due to the bioluminescence of organisms.

7. Structure cont. • Aphotic Levels: The next aphotic zone is the Abyssopelagic Zone. This zone reaches to the bottom floor, and only a few organisms are adapted to survive the extreme pressures and temperatures. It is also here that chemosynthetic organisms are found. There is an additional zone that reaches further down, called the Hadopelagic Zone that includes the areas in underwater trenches and canyons.

8. Ecosystem services • The open ocean offers multiple services. For organisms living it, it allows for constant moisture for plants and algae which in turn allows other organisms to feed on them. For humans, it is where a vast majority of fishing occurs, and due to how widespread it is, the open ocean is home to massive amounts of transportation.

9. Negative Human Activity • Human pollution has been a major threat to oceanic ecosystems. Pollution can kill organisms, such as destroying coral reefs or causing toxic algae blooms. It has been caused mostly by the dumping of used materials, and runoff from coastal cities carried by ocean currents. • Global warming has also been a major concern, as the acidity of the ocean level is rising, threatening the stability and diversity of the ocean. Increased carbon emissions cause this and the only way to alleviate it is to curb carbon emissions.