L4 Earth's Major Biomes II (Fall 2024-25) Notes PDF

L4: Earth’s Major Biomes II Dr. Cynthia Yau OCES1030 Environmental Science Fall 2024-25 Giant Tubeworms (Riftia) at a Hydrothermal Vent, Photo: NOAA  Lecture Outline Aquatic Biomes Freshwater Biomes Marine Biome...

L4: Earth’s Major Biomes II Dr. Cynthia Yau OCES1030 Environmental Science Fall 2024-25 Giant Tubeworms (Riftia) at a Hydrothermal Vent, Photo: NOAA  Lecture Outline Aquatic Biomes Freshwater Biomes Marine Biomes/Ecosystems Tidal shores: - Mangrove ecosystems - Estuaries and salt marshes Shallow Subtidal Communities: - Coral reefs - Kelp forests Deep-sea Communities: - Abyssal-benthic communities - Hydrothermal vent communities Reference: Cunningham et al. (2022), Chapter 5 2  AQUATIC BIOMES Aquatic biomes make up the largest of all the biomes on Earth, covering ~75% of Earth’s surface. Aquatic biomes can be broadly divided into: Freshwater biomes – e.g. lakes and rivers, have low concentrations of salt dissolved in the water (1000 m) – no sunlight at all. Abyssal zone (to 6000 m) and hadal zone (>6000 – 11,000 m) deepest zones – no sunlight, cold, high pressure. 14  Benthic vs Pelagic Marine biologists broadly categorize marine life depending if they live on or in the seabed - benthic, or live in the water column off the seabed – pelagic NOAA Pelagic - e.g. tunas Photo: C. Yau Benthic - e.g. crabs 15  Life in the Ocean Depth Zones High tide Low tide Pelagic realm (open water from surface to bottom) Oarweed Man-of-war Sea star Turtle Brain coral Photic Microscopic Microscopic zone Blue shark phytoplankton zooplankton 200 m Intertidal zone Continental shelf Sponges Sperm whale “Twilight” Sea pen Octopus Aphotic Hatchet fish zone Benthic realm Sea spider 1,000 m Gulper eel (seafloor from continental Rat-tail fish shelf to deep-sea bottom) Anglerfish No light Brittle star Glass sponge Sea cucumber Tripod fish 6,000– 10,000 m Oean zones are determined mainly by depth and therefore light levels, but also varies with temperature, pressure, and food availability. Ocean Zones - Nautilus Live (1:14 mins) https://www.youtube.com/watch?v=sE8JYv_cKng 16  Intertidal Shores 1: Mangrove Ecosystems Mangrove plants are a diverse Image: Mary Ann Cunningham group of salt-tolerant woody plants/trees that grow along warm, sheltered marine coasts in more tropical regions to form mangrove communities or ecosystems. They can tolerate periodic inundation of seawater at high tides. Mangrove communities support Photo: OzFish Unlimited high biodiversity and are high in productivity Mangrove trees can fix 3-5 times more CO2 than tropical forests on land 17  Intertidal Shores 2: Estuaries and Salt Marshes Estuaries are bays where rivers empty into the sea, mixing fresh Oceancolor. NASA water with salt water (estuarine or ‘brackish’ conditions) - Occur in any latitude. Pearl River Estuary Salt marshes: shallow wetlands flooded regularly or occasionally with seawater; occur along shallow, sheltered coastlines, Cunningham et al. including estuaries. - occur in more temperate latitudes. Salt marsh (grass-type vegetation) 18  Shallow Subtidal Zone 1: Coral Reefs Coral reefs are among the best- known marine ecosystems, because of their extraordinary high biodiversity and high biological productivity, as well as the many beautiful organisms they contain. Highest species diversity is in the tropics. Distribution of coral reefs Coral reefs – “rainforests of the sea” 19  Shallow Subtidal Zone 2: Kelp Forests Throughout the cooler temperate regions, hard subtidal substrates (i.e. rocky) are inhabited by a community dominated by large brown seaweeds, collectively known as kelps. – These form kelp beds (do not form a surface canopy) – or kelp forests (do form a surface canopy).  Seaweeds, or macroalgae, grow attached to the substrate by a holdfast (not roots, as do not absorb nutrients). 20 Kelp bed, U.K. Kelp forest, California U.S.  Deep-Sea 1: Abyssal-Benthic Communities The floor of ocean basins is called the abyssal plain (~4000- 6000 m depth). Animals that live on the bottom are termed “abyssal-benthic”, or “abyssal-pelagic” if they swim just above. Limited food availability supports only a sparse population of abyssal fauna and no plants ← no sunlight! University of Newcastle MBARI Abyssalpelagic rattail Abyssal plain benthos 21  Deep-Sea 2: Hydrothermal Vent Ecosystems Hydrothermal vents are a remarkable type of marine ecosystem that are independent MBARI of the sun’s energy. These dense, high diversity communities are based on microbes that use sulphur compounds Hydrothermal vent - suphide-rich black ‘smoke’ released from thermal vents on the ocean floor → chemosynthesis. Relatively newly-discovered E/V Nautilus communities (since 1977). WHOI (2:24 mins) What are hydrothermal vents? (2:24 mins) https://www.youtube.com/watch?v=xFAu8CqCtR8 MBARI Video (4:06 mins) https://www.youtube.com/watch?v=JtV-FP212Uc Giant tubeworms (Riftia) 22