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CHAPTER 15 Animals of the Benthic Environment
Distribution of benthic organisms
More benthic productivity beneath areas of high surface primary productivity Mainly on continental shelves Affected by surface ocean currents
Fig. 15.1
Benthic organisms on rocky shores Epifauna Epifauna (upon)(upon)
Attached to substrate (e.g., marine algae)
Move on/over seafloor (e.g., crabs, snails)
Moderate diversity of speciesGreatest animal diversity at
tropical latitudesGreatest algae diversity at
mid-latitudes (greater availability of nutrients due to lack of permanent thermocline in mid-lats)
http://dnr.metrokc.gov/wlr/waterres
www.portfolio.mvm.ed.ac.uk/studentwebs/session2
Intertidal zonation (rocky shore)
Fig. 15.2 a
Intertidal zonation (rocky shore)
Spray zone Spray zone (supratidal)(supratidal)Avoid drying outMany animals have
shellsFew species of
marine algae
Fig. 15.2b
www.mbari.org/staff/conn/botany/methods
Monterey Bay, CA
Intertidal zonation (rocky shore)
High tide zoneHigh tide zoneAvoid drying out so
animals have shellsMarine algae—rock
weeds with thick cell walls
http://www.woodbridge.tased.edu.au/mdc/Species%20Register/Barnacle-Tetra.jpg
http://www.ecology.org/ecophoto/algae/Thumbnails/Plant%20Images-10360.jpg
Intertidal zonation (rocky shore)
Middle tide zoneMiddle tide zoneMore types of marine algaeSoft-bodied animals
http://www.wallawalla.edu/academics/departments/biology/rosario/inverts/Mollusca/Bivalvia/Mytiloida/Mytilidae/Pisaster%20Predate%20mussels.jpg
Pisaster – sea star, mussel predator
http://www.dfw.state.or.us/mrp/shellfish/commercial/Images/flat_abalone.jpg
Abalone
Intertidal zonation (rocky shore)
Low tide zoneLow tide zoneAbundant algaeMany animals hidden by
sea weed and sea grassCrabs abundant in all
intertidal zones
http://www.fisherycrisis.com/chondrus/fig32.JPG
Benthic organisms on sediment-covered shores Similar intertidal zones Less species diversity
Greater number of organisms Mostly infaunainfauna – burrow into
sediment
Microbial communities
http://bivalves.info/Donax_hanleyanus.jpg
Coquina (Donax)
http://www.theseashore.org.uk/theseashore/Resources%20for%20seashoreweb/Images%20for%20New%20Pages/Donax.JPG
Coquina with valves extended
Intertidal zonation (sandy shore)
Fig. 15.8
Benthic organisms on sediment-covered shores
Energy level along shore depends onWave strengthLongshore current strength
Wave/current energy determines habitat…Coarse boulder beachesSand beachesSalt marshesMud flatsFine-grained, flat-lying tidal flat more stable
than high energy sandy beach
Sandy beaches Animals burrow Bivalve mollusks Annelid worms Crustaceans Echinoderms Meiofauna
Fig. 15-9
http://photography.nationalgeographic.com/staticfiles/NGS/Shared/StaticFiles/Photography/Images/POD/g/ghost-crab-hiding-760340-sw.jpg
Ghost crab hiding
Mole crab
Mud flats Eelgrass and turtle grass
common Bivalves and other mollusks Fiddler crabs
http://www.lacoast.gov/articles/bms/1/3_mud_flat_ground_view.jpg
http://www.sms.si.edu/irlspec/images/06PhotoContest/06DeWolfeH3.jpg
http://www.weeksbay.org/photo_gallery/shorebirds/SEMIPALMATED%20PLOVER.jpg
Shallow ocean floor Continental shelf Mainly sediment covered Kelp forest associated with rocky
seafloorAlso lobstersOysters
http://www.ianskipworth.com/photo/pcd1742/
kelp_forest_15_4.jpg
http://www.teara.govt.nz/NR/rdonlyres/ED9A6951-7B98-4AD2-A6A0-CA633137BE7C/74562/p4595doc.jpg
http://www.lifesci.ucsb.edu/~c_white/images/Lobsters%20in%20San%20Diego.JPG
Figure 15.14a,b
Figure 15.14c
Figure 15.16
http://wdfw.wa.gov/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=10996&g2_serialNumber=4
Coral reefs Most coral polyps live in large
colonies Hard calcium carbonate
structures cemented together by coralline algae
www.mpm.edu/imageswww.gettankedaquariums.com
http://www.h2o-mag.com/issue6/images_issue6/coral-01-copy.jpg
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
www.waterfrontchattanooga.com/Newsroom/High_reshttp://www.ee.bilkent.edu.tr/~aytur/pg
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 mutualistic relationship with
algae – zooxanthellae zooxanthellae Algae provide foodCorals provide nutrients
http://www.reefed.edu.au/explorer/images
Soft coral polyp (Lobophytum compactum). Green shows the polyp tissue, while the red shows the zooxanthellae.
www.bigelow.org/reefwatch2001/coral_reefs/images
Coral reef zonation Different types of corals at different depths
Fig. 15.19
Importance of coral reefs Largest structures
created by living organismsGreat Barrier Reef,
Australia, more than 2000 km (1250 m) long
Great diversity of species Important tourist locales Fisheries Reefs protect shorelines
http://www.sheppardsoftware.com/images/Oceania/factfile/GreatBarrierReef-EO.jpg
Great Barrier Reef from space
Humans and coral reefs 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
http://daac.gsfc.nasa.gov/oceancolor/images/coral_reef_algae.jpg
Coral covered with macroalgae
○ 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
www.stlucieco.gov/erd/threatened-endangered
• 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
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
Benthic organisms on the deep seafloor Little known habitat – only
accessable via dredge and some submersibles and ROVs
Bathyal, abyssal, hadal zonesBathyal, 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://www.whoi.edu/science/B/people/sbeaulieu/rad_patch_by_mound.jpg
http://library.thinkquest.org/17297/images/alvin.gif
http://www.amnh.org/nationalcenter/expeditions/blacksmokers/images/large/amnh19_18.jpg
Food sources in deep seafloor Most food sinks from surface waters Low supply and “patchy”
Fig. 15.22
Deep-sea hydrothermal vent biocommunities First discovered 1977 ChemosynthesisChemosynthesis Archaea use sea floor
chemicals to make organic matter
Unique communities Tube worms Giant clams and
mussels Crabs Microbial mats
http://i.treehugger.com/images/2007/10/24/deep-sea%20hydrothermal%20vent-jj-001.jpg
www.jamstec.go.jp/jamstec/organi/GOIN
Figure 15.27
Figure 15.25b
ChemosynthesisChemosynthesis Archaea use sea floor chemicals to make organic
matter
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 hypothesisDead 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
www.mbari.org
Whale carcass with worms, sea cucumbers
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 carcassOn ocean floor
Figure 15.C 1
Deep-sea hydrothermal vent biocommunities Life may have originated at hydrothermal
vents Chemosynthesis also occurs at low
temperature seepsHypersaline seepsHypersaline seepsHydrocarbon seepsHydrocarbon seepsSubduction zone seepsSubduction zone seeps
Figure 15.28 & 15.29
Figure 15.29b
Beneath the sea floor Deep biosphereDeep biosphere
Microbes live in porous sea floorMight represent much of Earth’s total biomass
http://oceanworld.tamu.edu/resources/oceanography-book/Images/Azam-(1998)-2.gif
In may 2008, prokaryotes were reported in mud cores extracted from between 860 to 1626 meters beneath the sea floor off Newfoundland. Cells were 100-1000 fold denser than in terrestrial cores of similar depth and about 5-10% of the cells were dividing.
http://environment.newscientist.com/channel/earth/deep-sea/dn13960-huge-
hidden-biomass-lives-deep- beneath-the-oceans.html