Oceanography and Hydrology

El Nino is a warm ocean current that temporarily replaces the cold Peruvian current, raising water temperatures by about 10°C. This warm current DECREASES plankton population since planktons thrive in cold nutrient-rich water. Therefore, statement D is NOT true because El Nino reduces planktons rather than increasing them.

Ocean currents are modified by multiple factors: Earth's rotation causes the Coriolis effect which deflects moving water (factor 1). Air pressure and wind systems drive surface currents through wind stress (factor 2). Ocean water density differences (due to temperature and salinity variations) drive thermohaline circulation and deep water formation (factor 3). Revolution of the earth (factor 4) affects seasonal patterns but is not a direct modifier of current flow. Therefore, factors 1, 2 and 3 directly modify ocean currents.

A seamount is a submarine mountain rising more than 1000 meters from the ocean floor (not 1 meter as stated). Guyots are flat-topped seamounts. Abyssal hills are smaller features under 1000m. Submarine ridges are large underwater mountain systems like the Mid-Atlantic Ridge.

Marine environments exhibit greater species diversity than continental ecosystems due to the ocean's vast size, longer evolutionary history, and wide variety of habitats from coastal zones to deep trenches. The ocean contains representatives of nearly all phyla, while terrestrial environments have more limited diversity.

Fiord coasts are formed when glacial valleys are flooded by the sea after glaciers retreat, creating narrow, steep-sided, elongated inlets. Ria coasts are drowned river valleys (broader and less steep), Haff coasts feature lagoons separated from the sea by barrier bars, and Dalmatian coasts have longitudinal valleys parallel to the coastline. The description perfectly matches fiord coasts.

Rheotaxis is a response to a current in a fluid. Positive rheotaxis is shown by fish turning to face against the current. In a flowing stream, this behaviour leads them to hold their position in a stream rather than being swept downstream. Some fish will exhibit negative rheotaxis where they will avoid currents.

A halocline is a cline caused by a strong, vertical salinity gradient within a body of water. As salinity (in concert with temperature) affects the density of seawater, it can play a role in its vertical stratification. Increasing salinity by one kg/m3 results in an increase of seawater density of around 0.7 kg/m3.

A psammosere is a seral community, an ecological succession that began life on newly exposed coastal sand. Most common psammoseres are sand dune systems.

Tides are the periodic rise and fall of sea water levels caused primarily by the gravitational pull of the moon and, to a lesser extent, the sun. Waves are caused by wind, and 'fiction' appears to be a typo or distractor. Tides occur in regular intervals depending on the lunar cycle.

The distance from the coast increases progressively: continental shelf (0-200m depth, extending from coastline), continental slope (steeper descent), continental rise (gentle slope at base), and finally abyssal plain (deepest ocean floor, typically 4000-6000m).

Statement 1 is correct - fold mountains running parallel to coastlines typically have narrow or absent continental shelves (like the Andes). Statement 2 is incorrect - continental shelf depth ranges from 0-200m, averaging 130m, not exactly 100m. Statement 3 is correct - submarine canyons are indeed common on continental slopes. Statement 4 is correct - guyots are flat-topped seamounts (submarine mountains).

Dalmatian coast is formed when parallel mountain ridges running along the coast are submerged, creating longitudinal islands and channels. This coastline type is named after the Dalmatian region of Croatia and is characterized by islands parallel to the mainland coast.