CHAPTER 15 Animals of the Benthic Environment

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 (on top)(on top)

Attached to substrate (e.g., marine algae)

Move on/over seafloor (e.g., crabs, snails)

Moderate diversity of speciesGreatest animal

diversity at tropical latitudes

Greatest algae diversity at mid-latitudes

http://dnr.metrokc.gov/wlr/waterres

www.portfolio.mvm.ed.ac.uk/studentwebs/session2

Intertidal zonation (rocky shore)

Fig. 15.2 a


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


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


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


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 on

Wave 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

Ever see a bivalve shell with a hole in it?

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 organismshttp://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 Bathyal, abyssal, hadal zoneszones 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

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

Misconceptions

Scientists have already studied all the Earth’s systems so there will not be any new discoveries.

Science always has exact answers.

Ocean Literacy Principles 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.

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CHAPTER 15 Animals of the Benthic Environment