Lecture 12 - Deep sea

two parts of deep sea

pelagic and benthic

pelagic

open ocean water column

benthic

at the bottom of the ocean floor

coverage of pelagic dark ocean

largest habitat on earth, covers 66% of earth’s surface, 95% of total ocean volume

what percent of the ocean is deeper than 1000m

79%

what percent of ocean microbes are in the pelagic dark ocean

75%

what percent of ocean microbes production is in the pelagic dark ocean

50%

what is considered dark ocean pelagic

>200m

what does the cold and pressurized dynamics of the dark ocean do

affects reaction kinetics, metabolic processes, enzyme activity, and membrane fluidity

why is the deep pelagic oxygenated

thermohaline circulation and cold water holds more oxygen

what is the volume distribution of water with depth

bathypelagic water is highest volume

why is hadal the lowest for volume distribution

very few trenches

main 4 sources of energy of deep sea/dark ocean organisms

1. fluxes of particulate matter

2. DOM that builds up in surface ocean waters during calm, stratified seasons and is then mixed, redistributed, and exported into deeper ocean layers

3. vertical migration of zooplankton and micronekton

4. chemoautotrophic production

what is the largest source of energy for deep sea organisms

fluxes of particulate matter

what percent of energy is fluxes of particulate matter used by deep sea organisms

80-90%

how does DOM do overturning convection

thermohaline circulation

overturning convection

vertical mixing and circulation process where surface water becomes dense and sinks deep into the ocean

what percent of energy for deep sea organisms is DOM from overturning circulation

10-20%

what is chemoautotrophy in the pelagic

deep sea microbes using inorganic carbon to organic

example of chemoautotrophy in pelagic

ammonia oxidation, sulfide oxidation, hydrogen oxidation

what is chemoautotrophy in benthic communities

hydrothermal vents

largest migration in terms of biomass

vertical migration of zooplankton and micronekton

what is the largest benthic habitat

abyssal plane

what percent of benthic habitat is the abyssal plane

60%

average depth of abyssal plane

4500m

what percent of surface production reaches abyssal plane

1-2%

average temp of abyssal plane

<3C

average salinity of abyssal

33-35ppt

most common invertebrates in abyssal plane

echinoderms: brittle stars, sea stars, sea cucumbers, sea urchins, crinoids

characteristics of abyssal plane

mostly sediment, no rocks, epifauna and epiphyte desert, high density of protists

other important invertebrates in abyssal plane

sea pens, stalked sea squirt, amphipods, isopods, polychaetes

order of organisms from 1000m onwards

sponges < sea cucumber < brittle stars and sea pens in coral reef < sea anemones < corals < polychaetes < echiurids < mollusca < crustaceans <others

what happens to biomass of benthic animals the deeper you go

decreases to < 0.01

deepest depth in ocean

mariana trench and second is tonga trench right outside mariana, very different characteristics

endemic species in deep ocean

many endemic to deep ocean

potential sources of food for deep sea organisms

1. sea grass detritus

2. zooplankton/fish migrations

3. plankton sinking

4. fecal pellet sinking

5. fish dumping

6. large fish and mammals dying

7. sargassum deitritus

adaptations of deep sea animals

1. camouflage by countershading

2. attracting prey with biolumnescent

3. avoiding prey with bioluminescence

4. finding food with large mouths

5. finding a mate

explain camouflage in deep sea

bioluminescence on belly makes fish body blend in with light above

example of camouflage

hatchet fish

explain attracting a prey in deep sea

use bioluminescence to lure prey

example of attracting a prey in deep sea

lanterns of angler fish

explain avoiding being prey in deep sea

using bioluminescence to startle predators

example of avoiding being prey in deep sea

copepods

explain finding food in deep sea

having a large mouth

example of finding prey in deep sea

gulper eel

explain how to find a mate in the deep ocean

tiny anglerfish male fuses with female, nurtured through female blood stream

how does the hatchetfish work

countershading using bioluminescence on the belly to look like light from above, microbes live in belly

hatchetfish

anglerfish

gulper eel

anglerfish male and female

two types of hydrothermal vents

1. warm diffuse flow (white smoker)

2. superheated plumes with dissolved minerals (black smoker)

temperature of two hydrothermal vents

white smoker is 5-100C and black smoke is 250-400C

why are there no bubbles with black smoke hydrothermal vents

due to pressure

characteristics of hydrothermal vents

low oxygen, high hydrogen sulfide, acidic (low pH), H2S toxic to cytochromes

what does it mean that H2S is toxic to cytochromes

the gas binds to a vital iron-containing enzyme in the mitochondria and shuts down normal cellular energy production

what does H2S do to cytochromes

stop cell respiration and causes irritation to humans at very high concentrations

where are vestimentifera not found

atlantic

when were hydrothermal vents first discovered

1977 galapagos with lots of vestimentifera

what is found in hydrothermal vents in atlantic instead of vestimentifera

shrimp!

explain cold water sinking into crust in hydrothermal vents

Cold, dense seawater sinks deep into the oceanic crust through rock fractures, where it is heated by magma and chemically transformed before rising back to the seafloor as a mineral-rich hydrothermal vent

explain dissolved metals and hydrogen sulfide in hydrothermal vents

superheated, acidic seawater leaches dissolved heavy metals and toxic hydrogen sulfide from the oceanic crust, which then erupt into the freezing deep ocean to build mineral chimneys and fuel entire chemosynthetic ecosystems

explain how hydrothermal vents are sites of chemosynthesis

Deep-sea microbes use the chemical energy from hydrogen sulfide in vent fluids—instead of sunlight—to convert carbon dioxide into nutrients, fueling entire food webs without photosynthesis.

who grazes on filamentous bacteria in hydrothermal vents

limpets and suspended bacteria from filtered water

riftia, vestimentifera

how are rifteria grouped

in annelida

morphology and size of rifteria

85cm/year, 3m long, no mouth but trophosome with symbiotic bacteria, bacteria live in trophosome

trophosome of rifteria

tubeworm captures dissolved oxygen, carbon dioxide, and highly toxic hydrogen sulfide,the resident bacteria use chemosynthesis—oxidizing the hydrogen sulfide to generate energy (ATP) and using it to fix carbon dioxide into organic molecules (carbohydrates)

bacteria in trophosome of riftia

make up 60% of dry weight of riftia

characteristics of pompej worm

lives in tubes close to hot vent, can sustain 80C small periods of 100C, bacteria live on surface, hottest animal on earth

pompeg worm

calyptogena magnifica

The red hemoglobin serves a dual purpose: it binds oxygen from the surrounding water, and it safely binds highly toxic hydrogen sulfide (H₂S). It transports both gases to the intracellular bacteria living in its tissues. The bacteria then use the sulfide via chemosynthesis to produce carbon compounds and sugars, effectively feeding the clam from the inside out

meiofauna in vents

nematods and copepods

macrofauna in vents

molluscs, annelids, crustacean

lifespan of hydrothermal vents

several years to decade, buried under lava

hot vent invertebrates

furry lobster

characteristics of furry lobster

bacteria that grow in fur may detoxify metals from vents or cultivate bacteria for food

lost city made of calcium carbonate, type of hydrothermal field

characteristics of lost city

found in 2003 ATL, 60m tall, lower temp than hot vents, methane and hydrogen rich, high pH, H2 and CH4 release, small amounts of CO2 and sulfide,

what happens with methanotrophs in lost city

methanotrophs with sulfate reduction deposit carbonate

characteristics of cold seeps

in subduction zones, discovered in GOM, sulfur and methane, shallower water, chemosynthetic production, limpets graze on bacterial mats

similarities of hot vents and cold seeps

biomass is high but species diversity is low

what does highbiomass but low species diversity do to hot vents and cold seeps

influences metal content in water

what do hydrothermal vent plumes do in pacific

supply micronutrients to water column, when they are upwelled we see phytoplankton blooms

fossil made by??? thought to have been extinct

another unknown feature in deep sea sediments