Unformatted text preview: CHAPTER 15
Animals of the Benthic Environment Chapter Overview Benthic communities include a variety of
habitats. Littoral (intertidal) Rocky Sediments
Continental shelf Florida Environments Coral reefs – require specific conditions
Abyssal plain Hydrothermal vents support diverse
communities that rely on chemosynthesis. Distribution of benthic organisms More benthic productivity beneath areas of high surface
primary productivity 98% of marine species, mainly on continental shelves
Affected by surface ocean currents
Biomass matches surface chlorophyll distribution. Fig. Benthic rocky shores Epifauna Sessile - Attached to substrate
(barnacles, 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
Intertidal Zone (rocky shore) Littoral zone – between
average high and low tides Harsh conditions organisms
must adapt to Drying out during low tide
Strong wave activity
Protection from predators
Changing conditions –
temperature, salinity, oxygen
content
Some species sessile Food
Reproduction
Competition for space to attach Intertidal zonation (rocky shore) Fig. 15.02 Intertidal zonation
(rocky shore) Spray zone (supratidal) Avoid drying out
Many animals have shells
Few species of marine
algae
Predator avoidance Isopod
Periwinkles cyanobacteria Intertidal zonation
(rocky shore) High tide zone Must avoid drying - animals
have shells
Marine algae - rock weeds with
thick cell walls Rocky intertidal zonation Middle tide zone More types of marine algae
Crabs and mollusks
Echinoderms – sea stars and
urchins
Soft-bodied animals Pisaster – sea star,
mussel predator Abalone Intertidal (Rocky) – Middle tide zone
Sea anemones Sea cucumber Hermit crab Brittle star Rocky intertidal - middle tide zone Sea Anemones Cnidaria – related to
jellyfish and coral Nematocysts for
capturing prey
Pull into tube-shaped
bodies above water pointreyesscience.wordpress.com
Intertidal zonation
(rocky shore) Low tide zone Abundant algae
Many animals hidden by sea
weed and sea grass
Crabs abundant
a/ Rocky Intertidal Tide pools Variety of algae
Softbodied and shelled
animals – snails,
echinoderms (starfish, sea
urchins), crabs
Euryhaline - Organisms
adapted to extreme changes
caused by evaporation dzonoquaswhistle.blogspot.com/2007/06/cape-ki... Physical Environment of
Sediment-Covered Shores Energy level along shore
depends on Wave strength
Longshore current strength Wave/current energy
determines habitat… Coarse boulder beaches
Sand beaches
Salt marshes
Mud flats
Tidal flats - fine-grained, flat- lying, more stable than high energy
sandy beach Sand beaches - ghost crabs
Mud flats – fiddler crabs Benthic organisms on
sediment-covered shores Similar intertidal zones
Less species diversity Coquina with valves extended
Greater number of organisms
Mostly infauna – burrow into sediment Meiofana and Microbial communities Fig. 15.08 Sandy beaches Bivalve mollusks
Annelid worms – sand
worms
Crustaceans - crabs Sand dollar Echinoderms Sand crab/sand flea Animals burrow Sea urchins, sand dollars Meiofauna – microscopic Meiofauna Ghost crab hiding Fig. 15.09
Sandy Beach Organisms Meiofauna Small, feed on bacteria
Polychaete worms, mollusks,
arthropods, nematodes
(round worms). Mud flats Marsh grasses
Sea grasses – (submerged)
eelgrass and turtle grass
common
Bivalves and other mollusks
Fiddler crabs
Birds - feeding
Fiddler crabs
Shallow Offshore Communities
Subtidal – continental
shelf Rocky or sandy Kelp (Kingdom Protista) Associated with rocky seafloor
and high energy coastline
Holdfasts – anchor kelp
Pneumatocysts – gas-filled, keep
large species upright
Holdfasts Shallow ocean floor Kelp forest (Kingdom Protista) Beds of giant brown bladder kelp and bull kelp
Fast growing
Highly productive ecosystems
Shelter for variety of organisms Kelp bed distribution Fig.15.14c Shallow ocean floor Rocky benthic usually more
diverse than sandy benthic Greater variation of habitat
Protection from predators
Lobster and crabs
Variety of fish Benthic fish dorso-ventrally
(top to bottom) flattened - Shallow ocean floor Florida and the Caribbean Less wave action – sandy/rocks Queen Conch Sea grasses and algae
Conch and other large mollusks
Spiny lobster
Stingray
Horse
Conch
Spiny lobster Worm rock reefs • Colonies of Sabellariid sand worms
(Phragmatopoma caudata) form shallow
reefs by cementing sand tubes together
• St. Augustine to south end of Biscayne
Bay – Bathtub Reef in St. Lucie Co.
• Provide habitat for many organisms Coral reefs Coral reef - most coral polyps
live in large colonies Feed with stinging tentacles
Related to jellyfish Hard calcium carbonate structures Symbiosis of coral and algae Coral reefs made of algae, mollusks, foraminifers
as well as corals
Hermatypic coral - mutualistic relationship with
algae – zooxanthellae (dinoflagellate) Algae provide food
Corals provide nutrients
ges Soft coral polyp (Lobophytum
compactum). Green shows the
polyp tissue, while the red shows
the zooxanthellae. Coral reefs Coral reefs limited to: Warm (but not hot) seawater
Under 30oC (86oF)
Strong sunlight (for symbiotic algae) Strong waves or currents
Clear seawater - low nutrients
Normal salinity
Hard substrate Coral reefs Most diverse of all
marine ecosystems More diverse on western
boundaries of oceans
Tropical - surface
circulation warmer water
Fringe islands and
shallower water
Greatest diversity - western
Pacific and Indian oceans Reef-building corals Fig. 15.18 Coral reef zonation Different types of corals at different depths Fig. Coral reef zonation . 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 – 1/3 of species
Reefs protect shorelines
Great Barrier Reef
from space - Crown-of-thorns starfish and reefs Crown-of-thorns sea star - eats
coral polyps (Pacific ocean)
Outbreaks (greatly increased
numbers) decimate reefs Collecting of large shell of Pacific
Triton’s trumpet – reduced population of
a major predator of starfish
Fig. 15.21 Coral reefs in decline
30% healthy today, 41% healthy in 2000 One third of corals – high risk of extinction Humans – greatest threat
Anchor Destructive fishing practices
Tourist collecting
Boat anchors damage Cyanide “fishing”
%20to%20Coral%20Reefs%20M4 Coral reefs in decline Pollution - Sewage and agricultural fertilizers
increase nutrients in reef waters Hermatypic corals thrive at low nutrient levels
Algae overwhelm at high nutrient levels – Smothered by algae
Bioerosion of coral reef by algae-eating organisms Coral covered with macroalgae Parrot fish eating coral
.
jpg Humans and coral reefs Other problems Sediments from
construction or dredging
smother coral
Fishing practices,
harvesting - Overfishing Sedimentation Humans and coral reefs Coral bleaching Water that is too warm causes loss of symbiotic algae,
the coral’s primary
energy source.
Elevated UV levels
Can recover if condition is temporary
Often occurs during El Nino events Coral bleaching Dots show sites of coral bleaching
Normal and Bleached Coral Climate change/global warming Coral reefs are affected
by climate change Increased storm activity
– tears up coral reefs
Sea level rise – affects
light penetration
Increased precipitation
– lowers salinity
Ocean temperature
increase – causes coral
bleaching
Ocean acidification Dissolves coral Great Barrier Reef before
and after Cyclone Ita
(2014) Climate change/global warming Coral reefs are affected by climate change Increased CO2 causes acidification – corals dissolve Deep-Ocean Floor Communities Less known about than shallower water
communities Expensive to explore the deep
only accessible via dredge and some submersibles
and ROVs
Robotic technology for exploration
editions/blacksmokers/images/large/am
f Benthic organisms on the deep seafloor Most common habitat on Earth Little known habitat bathyal, abyssal, hadal zones Light absent below 1000 m (3300 feet)
Temperature usually between − 1.8°C (28.8°F) and 3°C (37°F)
About the same salinity
Oxygen content relatively high
Pressure can be enormous
Bottom currents usually slow
crab.jpg
/01/Coryphaenoides_videograb.jpg Food sources in deep seafloor Most food sinks from surface waters
Low supply and “patchy” Fig. 15.24 Deep sea benthos Deposit feeders Large filter feeding animals are
rare (food scarce) Crinoids, sponges, sea cucumbers,
deep-sea corals
Predators – fish, sea stars, brittle
stars Blind lobster
Brittle stars and sea
stars Crinoid
ce/04benthon/dsbenthos.htm Deep sea coral
phelia/background/biology/media/biology1_600.j Deep sea benthos Long appendages to move
about in deep soft sediment
Chimera
Tripod fish Sea pig (sea
cucumber) Giant sea spider Deep-Sea Hydrothermal Vent Communities Hydrothermal vent communities - Discovery
– WHOI Alvin in 1977 Galapagos Rift in Pacific Ocean
Surrounding water temp 8 –12°C (46–54°F) Much higher than normal deep sea temp
Chimney vents, hot acidic water ?
articles.view/articleNo/32523/title/Life-onthe-Ocean-Floor--1977/
Deep-Sea Hydrothermal Vent Communities Hydrothermal vent
biocommunities Organisms previously
unknown to science
Unusually large for depth
in ocean Black smokers –
underwater chimney vents
emit sulfides Deep-sea hydrothermal vent communities Unique communities Giant tube worms
Giant clams and
mussels
Crabs and shrimp
Microbial mats
Predatory fish
Life supported by
chemosynthesis Chemosynthesis Microscopic archaea – thrive on hydrogen
sulfide from vents Manufacture sugar from hydrogen sulfide, carbon
dioxide, and dissolved oxygen Fig 15.27 Chemosynthesis Base of hydrothermal vent food chain Worms, clams and mussels – symbiotic
relationship with archaea
ml Global hydrothermal and cold seep
chemosynthetic communities Fig. 15.26 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 Possible dispersal to carcasses – support vent organisms
Take years to decompose
Use as "stepping stones “ Whale carcass with
worms, sea cucumbers Low Temperature Chemosynthesis
Chemosynthesis also occurs
at low temperature seeps Hydrocarbon seeps Oil and gas seeps
Hydrogen sulfide and/or
methane Figure 15.31 Low-Temperature Seeps Hypersaline seeps - salinity ~46 ppt, rich in hydrogen sulfide
Florida Escarpment – seeping
water from limestone fractures
Support a diverse community Fig 15.30 Low-Temperature Seep Biocommunities Subduction zone seeps Juan de Fuca plate
Folded sedimentary rocks
Chemosynthetic Archaea
feed on methane Global hydrothermal and cold seep
chemosynthetic communities Fig. 15.26 Climate changes in the Oceans
Chapt 16 Pg 542-553 Increasing ocean temperatures Sea surface temps risen mostly since 1970
Deep waters showing increases Changes in the Oceans
Changes in air and water circulation
North Atlantic especially sensitive Melting glaciers – warmer poles Forces cold air further south over U.S. Warmer oceans More frequent and intense storms Changes to ocean thermohaline
circulation Potential loss of oxygen to the deep sea
resulting in anoxic bottom conditions
nt/noaa-arctic-futures-site Dead crabs and fish at the
bottom of the Baltic sea due
to anoxic bottom conditions Dissolved carbon dioxide and ocean pH
Ocean acidity increase Some atmospheric carbon dioxide dissolves in
ocean water to become carbonic acid. Acidifies ocean Changes in the Oceans
Ocean acidity increase Threatens calcifying organisms Coccolithophores
Foraminifers
Mollusks
Sea urchins
Corals
Anything with a
calcareous shell Fig 16.26 Changes in the Oceans
Other predicted changes Reduced dissolved oxygen – increase in dead zones
Change in ocean productivity Migration of mangroves Increased ocean stratification and stronger thermocline
Decreased productivity due to diminished upwelling
Decline in global phytoplankton biomass
Florida’s mangroves migrating north Marine organisms unable to adapt to temperature changes Reducing Greenhouse Gases Human emissions contributing to
excessive CO2 in Earth’s atmosphere
Global engineering – attempts to counteract humancaused climate change Reducing sunlight reaching earth
Removing human-caused greenhouse gases
1/feb/18/geo-engineering Reduce CO2 emissions IPCC - Intergovernmental Panel on Climate
Change (1988)
Kyoto Protocol (1997) – Intergovernmental Negotiating
Committee of the UN Meeting negotiated in Kyoto, Japan The goal was to reduce worldwide greenhouse gas
emissions to 5.2 percent below 1990 levels Most of the world’s industrialized nations (191)
support the Kyoto Protocol. Notable exception - the United States, which releases
more greenhouse gases than any other nation and
accounts for more than 25 percent of those
generated by humans worldwide. The U.S. signed
the treaty (1998) To this date, but congress has failed
to ratify it. Reducing greenhouse gases
Greater fuel efficiency Alternative fuels Re-forestation Eliminate
chlorofluorocarbons Ocean’s role in reducing CO2 Ocean’s biological pump
CO2 incorporated in
organisms and
carbonate shells (tests) Stored as biogenous
calcareous sediments
and fossil fuels Ocean is repository or
sink for CO2 Increases ocean acidity
enough to affect
organisms (corals) Fig 16.32 Ocean’s role in reducing CO2 Iron Hypothesis - add iron
to fertilize ocean to
increase productivity
Increase phytoplankton,
increase carbon dioxide
removal from atmosphere
Plankton die and fall to
bottom, sequestering CO2 in
sediment
May not affect global CO2
levels significantly
May cause unknown problems
in ocean ecology Fig 16.34 What can you do to affect change? (See Afterword pg in text)
Drive smart – keep your vehicle tuned
and the tires properly inflated Make smart choices in vehicles Do you really need that 8 cylinder SUV? Go green – support non-fossil fuel
energy Switch lights – use energy efficient
fluorescent and LED lights Replace appliances with energy
efficient models What you do to affect change? Properly insulate and
weather strip your home
Plant trees and protect
plant communities Reduce, reuse and
RECYCLE Be smart about how
you consume water VOTE – be aware of
the positions of your
candidates Educate – yourself and
your kids. Bad habits
are often learned from
parents Marine resources management Afterword – Pages 550-553 Public must see the fundamental need to manage and
conserve our coastal resources Education - “In the end we conserve what we love. We love
only what we understand. We will understand only what we are
taught”.
Multidisciplinary – partnership between business, politicians
educational institutions and government scientists (DEP) - Marine resources management Coral reef and estuary management – protect breeding and nursery
habitat of important fishery species
provide and keep jobs Protect beaches and coral reefs as recreational
resources
tourist dollars
Enforcement of regulations
Monitor biophysical conditions – effects of climate change and
pollution
Fund applied research to improve resources and to better
understand the physical, biological and chemical aspects of ocean
systems
Increase the number of MPA’s – Marine Protected Areas
8/ArticleID/11701/Simone-Alin-Monitoring-the-rapidly-changing-chemistry-of- Marine Protected Areas U.S. National Marine Sanctuaries 14 Marine protected areas (MPA)
~ 47,000 sq k (18,000 sq m)
Includes the Florida Keys What can YOU do to reduce ocean
pollution? Snip plastic six-pack rings
and be careful what you do
with fishing line
Reduce use of laundry
detergent, lawn fertilizers
and pesticides
Clean up after your pet
Take care of vehicle leaks
quickly
Drive less, carpool
For groceries - use fabric
bags or recycle plastic bags What can you do to reduce ocean pollution? Don’t release balloons
DON’T LITTER – All
canals drain to the lagoon Volunteer for beach
cleanup
Inform and Educate
others End of CHAPTER 15
Animals of the
Benthic Environment ...
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