Lecture 12 Flashcards
(44 cards)
What are the depth zones in the ocean?
- Sublittoral
- Bathyal
- Abyssal
- Hadal
- Trenches
What is the largest habitat on the planet?
- The deep sea
After which depth zone is considered the deep sea?
- After sublittoral
What is the temperature, pressure, and light like in deep sea physical environment?
- Temperature: in general very cold 4 to -1.9 C
- Pressure: extremely high, 1 atm increase per 10m depth
- Light: abyssal and Hadal zones are dark; very little light in bathyal
What is the food availability like in the deep sea physical environment?
- Very nutrient poor
What is the food availability in the deep sea dependent on?
- Almost entirely dependent on outside energy sources-> falling plant debris, fecal pellets, carcasses, Whale fall
Why are fecal pellets important?
- It’s like a conveyer belt that moves carbon from surface waters down to the deepest oceans; a very important part of the Carbon Cycle
What is a Osedax? When was it discovered?
- A bone eating worm; a genus of siboglinid polychaete annelids (Polychaete Worm)
- Discovered in 2002
Who is the close relative to Osedax?
- Hydrothermal vents worms such as Riftia
Why is the physical environment of the deep sea predictable?
- Because there is little or no seasonal variation in temperature
What are some important disturbances that happen in the deep sea?
- Bioturbation, benthic storms, whale falls, etc.
- Infrequent but important
Is the communities in the deep sea very or lowly diverse?
- Very diverse communities
What is known about the species numbers? Distribution?
- Little is known about the species numbers in most areas of the deep sea; still very difficult to sample
- Patchy distribution of species- richness can vary substantially from one sample to another
Where is the highest diversity found in the waters?
- Highest diversity usually always found in mid-depth waters
What is a Megafauna?
- Large moving or sessile
- Echinoderms, anthropoids, mollusks, fishes
What is the largest organisms in the deep sea?
- Megafauna
What is known about swim bladders and buoyancy in Megafauna fishes? Depth?
- Most have lost swim bladders and are negatively buoyant
- Known from 7.2 km depth
What are the sessile Megafauna?
- Large anemone, mushroom coral, anemone, and sea pens
What are Macrofauna?
- Anything retained on 1 mm mesh screen
- Polychaetes, small crustaceans, mollusks, etc.
What is the level of diversity for Macrofauna?
- Very high diversity
Which is bigger between Megafauna and Marcofauna?
Megafauna
What is Meiofauna? Size?
- Anything smaller than 1 mm
- Nematodes, copepods, ostracods, flatworms, polychaetes, etc.
What is the diversity of Meiofauna?
- Very diverse but still very poorly known even in shallow water
What are the hypotheses on the causes of the deep-sea diversity?
1) Stability- time hypothesis
2) Biological disturbance
3) Patchy food resources
4) Large areas
