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