Transcript Chapter 15: Animals of the benthic environment

CHAPTER 15
Animals of the Benthic Environment
Distribution of benthic organisms
Fig. 15.1

More benthic productivity beneath areas of high surface primary
productivity
 Mainly on continental shelves
 Affected by surface ocean currents
www.portfolio.mvm.ed.ac.uk/studentwebs/session2
Benthic organisms on rocky
shores

Epifauna (on top)
 Attached to substrate (e.g.,
marine algae)
 Move on/over seafloor
(e.g., crabs, snails)

Moderate diversity of
species
 Greatest animal diversity at
tropical latitudes
 Greatest algae diversity at
mid-latitudes
http://dnr.metrokc.gov/wlr/waterres
Intertidal
zonation
(rocky
shore)
Fig. 15.2 a
Intertidal zonation
(rocky shore)

Fig. 15.2b
Spray zone
(supratidal)
 Avoid drying out
Monterey Bay, CA
 Many animals have
shells
 Few species of marine
algae
www.mbari.org/staff/conn/botany/methods
http://www.woodbridge.tased.edu.au/mdc/Species%20Register/Barnacle-Tetra.jpg
Intertidal zonation (rocky
shore)

High tide zone
 Avoid drying out so
animals have shells
 Marine algae—rock
weeds with thick cell
walls
http://www.ecology.org/ecophoto/algae/Thumbnails/Plant%20Images-10360.jpg
Intertidal zonation
(rocky shore)

http://www.dfw.state.or.us/mrp/shellfish/commercial/Images/flat_abalone.jpg
Abalone
Middle tide zone
 More types of marine algae
 Soft-bodied animals
Pisaster – sea star,
mussel predator
http://www.wallawalla.edu/academics/departments/biology/rosario/inverts/Mollusca/Bivalvia/Mytiloida/Mytilidae/Pisaster%20Predate%20mussels.jpg
http://www.fisherycrisis.com/chondrus/fig32.JPG
Intertidal zonation
(rocky shore)

Low tide zone
 Abundant algae
 Many animals hidden by sea
weed and sea grass
 Crabs abundant in all
intertidal zones
http://bivalves.info/Donax_hanleyanus.jpg
Benthic organisms on sediment-covered
shores


Similar intertidal zones
Less species diversity
 Greater number of organisms
 Mostly infauna – burrow into
sediment

Microbial communities
Coquina with valves extended
Coquina (Donax)
http://www.theseashore.org.uk/theseashore/Resources%20for%20seashoreweb/Images%20for%20New%20Pages/Donax.JPG
Intertidal zonation (sandy shore)
Fig. 15.8
Benthic organisms on sediment-covered
shores

Energy level along shore depends on
 Wave strength
 Longshore current strength

Wave/current energy determines habitat…
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Coarse boulder beaches
Sand beaches
Salt marshes
Mud flats
Fine-grained, flat-lying tidal flat more stable
than high energy sandy beach
Sandy beaches
Mole crab
Animals burrow
 Bivalve mollusks
 Annelid worms
 Crustaceans
 Echinoderms
 Meiofauna

Ghost crab hiding
Fig. 15-9
http://photography.nationalgeographic.com/staticfiles/NGS/Shared/StaticFiles/Photography/Images/POD/g/ghost-crab-hiding-760340-sw.jpg
http://www.weeksbay.org/photo_gallery/shorebirds/SEMIPALMATED%20PLOVER.jpg
Mud flats
Eelgrass and turtle grass
common
 Bivalves and other mollusks
 Fiddler crabs

http://www.sms.si.edu/irlspec/images/06PhotoContest/06DeWolfeH3.jpg
http://www.lacoast.gov/articles/bms/1/3_mud_flat_ground_view.jpg
http://www.teara.govt.nz/NR/rdonlyres/ED9A6951-7B98-4AD2-A6A0-CA633137BE7C/74562/p4595doc.jpg
Shallow ocean floor
Continental shelf
 Mainly sediment covered
 Kelp forest associated with rocky seafloor

 Also lobsters
 Oysters
http://www.lifesci.ucsb.edu/~c_white/images/Lobsters%20in%20San%20Diego.JPG
http://www.ianskipworth.com/photo
/pcd1742/kelp_forest_15_4.jpg
Figure 15.14a,b
Figure 15.14c
Ever see a bivalve shell with a hole in it?
http://www.h2o-mag.com/issue6/images_issue6/coral-01-copy.jpg
Coral reefs

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Most coral polyps live in large
colonies
Hard calcium carbonate
structures cemented together
by coralline algae
www.gettankedaquariums.com
www.mpm.edu/images
Coral reefs

Coral reefs limited to
 Warm (but not hot) seawater
 Sunlight (for symbiotic algae)
 Strong waves or currents
 Clear seawater
 Normal salinity
 Hard substrate
http://www.ee.bilkent.edu.tr/~aytur/pg
www.waterfrontchattanooga.com/Newsroom/High_res
Reef-building corals
Fig. 15-17
Symbiosis of coral and algae
Coral reefs made of algae, mollusks, foraminifers as
well as corals
 Hermatypic coral mutualistic relationship with algae
– zooxanthellae
 Algae provide food
 Corals provide nutrients

Soft coral polyp (Lobophytum compactum). Green
shows the polyp tissue, while the red shows the
zooxanthellae.
www.bigelow.org/reefwatch2001/coral_reefs/images
http://www.reefed.edu.au/explorer/images
Coral reef zonation

Different types of corals at different depths
Fig. 15.19
http://www.sheppardsoftware.com/images/Oceania/factfile/GreatBarrierReef-EO.jpg
Importance of coral reefs

Largest structures created
by living organisms
 Great Barrier Reef, Australia,
more than 2000 km (1250
m) long
Great diversity of species
 Important tourist locales
 Fisheries
 Reefs protect shorelines

Great Barrier Reef
from space
Humans and coral reefs

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Activities such as fishing, tourist
collecting, sediment influx due to
shore development harm coral
reefs
Sewage discharge and agricultural
fertilizers increase nutrients in reef
waters
 Hermatypic corals thrive at low
nutrient levels
 Phytoplankton overwhelm at high
nutrient levels
 Bioerosion of coral reef by algae-eating
organisms
Coral covered with macroalgae
http://daac.gsfc.nasa.gov/oceancolor/images/coral_reef_algae.jpg
○
Other problems
Smoothering by
dredging, runoff
 Fishing practices,
harvesting
 Pollution
 Global warming

http://images.wri.org
Large vs. small reef fish: Fishery management regulations such as
minimum sizes allow fishermen to keep only the largest fish. As shown by
the red snapper example, the largest fish produce the most eggs. One
24-inch red snapper produces the same number of eggs as 212 17-inch
red snapper. So, by selectively removing the largest fish, the fishery
removes the fish that have the greatest potential for producing more fish.
ttp://oceanexplorer.noaa.gov/explorations/02sab/logs/aug05/media
Crown-of-thorns starfish and reefs
Sea star eats coral
polyps
 Outbreaks
(greatly increased
numbers)
decimate reefs

Fig. 15.21
Worm Reefs •
Sabellariid worms (Phragmatopoma
caudata) form shallow reefs
• St. Augustine to south end of
Biscayne Bay
• Provide habitat for many organisms
www.floridaoceanographic.org/environ/images
www.stlucieco.gov/erd/threatened-endangered
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Adult worms (3/4 - 2 in. long) build reefs on limestone and
coquina formations, jetties
Build sand hoods over tubes to reduce desiccation at low tide.
Protective tubes made of sand, joined to neighbors to build rigid,
wave resistant structures.
15,000 to 60,000 worms per m2
Live up to 10½ years.
Thais (oyster drill) is an important predator
http://www.amnh.org/nationalcenter/expeditions/blacksmokers/images/large/amnh19_18.jpg
Benthic organisms on the
deep seafloor

Little known habitat – only
accessable via dredge and some
submersibles and ROVs

Bathyal, abyssal, hadal zones
 Little to no sunlight
 About the same temperature
 About the same salinity
 Oxygen content relatively high
 Pressure can be enormous
 Bottom currents usually slow
http://library.thinkquest.org/17297/images/alvin.gif
http://www.whoi.edu/science/B/people/sbeaulieu/rad_patch_by_mound.jpg
Food sources in deep seafloor
Most food sinks from surface waters
 Low supply and “patchy”

Fig. 15.22
http://i.treehugger.com/images/2007/10/24/deep-sea%20hydrothermal%20vent-jj-001.jpg
Deep-sea hydrothermal vent
biocommunities
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First discovered 1977
Chemosynthesis
Archaea use sea floor
chemicals to make
organic matter
Unique communities
 Tube worms
 Giant clams and mussels
 Crabs
 Microbial mats
www.jamstec.go.jp/jamstec/organi/GOIN
Figure 15.27

Chemosynthesis
 Archaea use sea floor chemicals to make organic matter
Figure 15.25b
Global hydrothermal vent fields
Fig. 15.24
Deep-sea hydrothermal vent
biocommunities
Vents active for years or decades
 Animals species similar at widely separated
vents
 Larvae drift from site to site
 “Dead whale hypothesis”

○
“Dead whale hypothesis” – Dispersal of vent organisms
 Pelagic eggs/larvae disperse to other food patches or vent
fields
- Methane-bearing springs on continental shelves and
slopes are more common than originally thought
- Possible dispersal to carcasses – support vent organisms
- Take years to decompose
- Use as "stepping stones
Whale carcass with
worms, sea cucumbers
www.mbari.org
On whale bones, only the pinkish trunk of this cross-section of a female
Osedax tubeworm is visible. The white blobs are ovaries where more than
100 dwarf male tubeworms can live inside the female. Symbiotic bacteria
give the tubeworm's roots their greenish color. Bacteria in the roots of
Osedax produce nutrients by processing the fats and lipids in the bones
of whales.
www.geotimes.org/aug04
Figure 15.C
Fish carcass
On ocean
floor
Deep-sea hydrothermal vent
biocommunities
Life may have originated at hydrothermal vents
 Chemosynthesis also occurs at low temperature
seeps

 Hypersaline seeps
 Hydrocarbon seeps
 Subduction zone seeps
Figure 15.28 & 15.29
Figure 15.29b
http://oceanworld.tamu.edu/resources/oceanography-book/Images/Azam-(1998)-2.gif
Beneath the sea floor

Deep biosphere
 Microbes live in porous sea floor
 Might represent much of Earth’s total biomass
In may 2008, prokaryotes were
reported in mud cores extracted
from between 860 to 1626 meters
beneath the sea floor off
Newfoundland. Cells were 1001000 fold denser than in terrestrial
cores of similar depth and about 510% of the cells were dividing.
http://environment.newscientist.com/channel/earth/
deep-sea/dn13960-huge-hidden-biomass-livesdeep- beneath-the-oceans.html
Misconceptions
Scientists have already studied all the
Earth’s systems so there will not be any
new discoveries.
 Science always has exact answers.
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Ocean Literacy Principles
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3e. - The ocean dominates the Earth’s carbon cycle. Half the primary productivity on Earth takes place in
the sunlit layers of the ocean and the ocean absorbs roughly half of all carbon dioxide added to the
atmosphere.
5a. - Ocean life ranges in size from the smallest virus to the largest animal that has lived on Earth, the blue
whale.
5b. - Most life in the ocean exists as microbes. Microbes are the most important primary producers in the
ocean. Not only are they the most abundant life form in the ocean, they have extremely fast growth rates
and life cycles.
5c. - Some major groups are found exclusively in the ocean. The diversity of major groups of organisms is
much greater in the ocean than on land.
5d. - Ocean biology provides many unique examples of life cycles, adaptations and important relationships
among organisms (symbiosis, predator-prey dynamics and energy transfer) that do not occur on land.
5e. - The ocean is three-dimensional, offering vast living space and diverse habitats from the surface
through the water column to the seafloor. Most of the living space on Earth is in the ocean.
5f. - Ocean habitats are defined by environmental factors. Due to interactions of abiotic factors such as
salinity, temperature, oxygen, pH, light, nutrients, pressure, substrate and circulation, ocean life is not
evenly distributed temporally or spatially, i.e., it is “patchy”. Some regions of the ocean support more
diverse and abundant life than anywhere on Earth, while much of the ocean is considered a desert.
5g. - There are deep ocean ecosystems that are independent of energy from sunlight and photosynthetic
organisms. Hydrothermal vents, submarine hot springs, methane cold seeps, and whale falls rely only on
chemical energy and chemosynthetic organisms to support life.
5h. - Tides, waves and predation cause vertical zonation patterns along the shore, influencing the
distribution and diversity of organisms.
5i. - Estuaries provide important and productive nursery areas for many marine and aquatic species.