Animals of the Benthic Environment PDF

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Lecture notes of animals of the benthic environment in the ocean...

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Chapter Fifteen: Animals of the Benthic Environment Overview Review the types of benthic life organisims that live on or near the seafloor shorelines, coral reefs, and hydrothermal vents and discuss the different communities found in each area. Most of the rocks found in Indiana, especially the limestone, tells us that our state was once covered by a warm, shallow sea. rocks are remains of the seafloor during that time fossils tells us what the ocean and climate were like in the past.

Chapter 15 Benthic Life Objectives Overal Learning Objectives 15.1 Specify characteristics of the communities that exist along rocky shores 15.2 Specifiy characteristics of the communities that exist along sedimentcovered shores 15.3 Specify characteristics of the communities that exist on the shallow offshore ocean floor 15.4 Specifiy characteristics of the communities that exist on the deep-ocean floor

Specific learning Objectives Define benthic biomass and describe the worldwide distribution of benthic biomass and its relationship to primary productivity

Define epifauna and give some examples of epifauna found along rocky shores Differentiate between the spray zone, high tide zone, middle tide zone, and low tide zone. Describe the adverse conditions of rocky intertidal zones and organisms' adaptions for those conditions. Identify the adverse conditions that seem to be most important in controlling the distribution of life on rocky coasts. Describe the environmental hardships of organisms that inhabit each rocky shore intertidal zone, give an example of one, and discuss that organism's adaptions that allow it to survive in its particular zone. One of the most noticebale features of the middle tide zone along rocky coasts is a mussel bed. Describe general characteristics of mussels and inlcude a discussion of other organisms that are associated with mussels Discuss which intertidal zone of a rocky shore would you typically find each of the following organisms sea anemones sea lettuce rock lice abalones brittle stars buckshot barnacles Describe the characteristic features of sea anamones and the utility of their stinging cells Define infuana and give some examples of infauna found along sedimentcovered shores Describe the intertidal zonation of sediment-covered shores, and common organims in each zone. Describe how sandy and muddy shores differ in terms of energy level, particle size, sediment stability, and oxygen content

Describe bivalve mollusks and their adaptions for feeding on sediment-covered shores Describe the characteristics of crustaceans and give examples of crustacean species and their feeding habits. Describe echinoderms, give examples, and discuss their feeding patterns Define meiofauna and give exampls Compare the species diversity on sediment-covered shores as compared to rocky shores and reasons for their differences On a steeply sloping, coarse-sand each, discuss where you would find the following: clams beach hoppers ghost shrimp sandcrabs heart urchins Discuss common organisms of mud flats and their adaptions for living and feeding in muddy sediments Describe the subtidal zone and list examples of organisms found in this zone Describe the dominant species of kelp, their epifauna, and animals that feed on kelp in Pacific coast kelp forests Discuss the differences between spiny and American lobsters Describe oysters, where they are found, and their importance in providing food to other organisms. Define coral reef and discuss composition of such organisms Discuss the worldwide distribution of coral reefs Where are they most often found and why? Describe the enviormental conditions required for development of coral reefs

Identify some of the symbiotic relationships in coral reefs, including the symiosis of coral and algae Give examples of the importance of coral reef enviornments Imagine a 20 foot change in sea level, both increased and decreased, and discuss its impact on coral reef zonation Draw and describe each of the three stages of coral reef development. how does this sequence tie into plate tectonics? Describe the zones of the reef slope, the characteristic coral types, and the physical factors related to its zonation Discuss the changed in reef benthic communities with increasing nutrient levels Describe coral bleaching, how and why bleaching occurs, and where bleaching is currently happening worldwide Discuss other threats to coral reefs Describe the food source of organsims living on the deep-ocean floor and its impact on the benthic biomass of deep-sea communities Describe the charactistics of hydrothermal vents and discuss why these features are relatively short lived. Explain the "dead whale hyptohesis" and other ideas suggested to explain how organisms from hydrothermal vent biocommunities populate new vent sites Differentiate between hypersaline seeps, hydrocarbon seeps, and subduction zone seeps in terms of their enviormental condtions and their charactistic marine life. Using Figure 15.28, discuss the major differences between chemosynthesis and photosynthesis from a chemical standpoint. Describe the similariteis and differences betweeen the conditions and biocommunities of hydrothermal vents and cold seeps Discuss changes in the physical enviorment that occur as one moves from the shoreline to the deep-ocean floor.

Chapter 15 (Benthic Life) Lecture Chapter Overview Benthic communiites exist in a varity of habitats, including rocky shores, sediment-covered shores, the shallow offshore ocean floor, and the deep-ocean floor Corals need specific environemntal conditions Hydrothermal vents support diverse communities that rely on chemosynthesis

Distribution of Benthic Organisms More than 98% of approximately 230,000 known marine species live in or on ocean floor Benthic organisms live mainly on continental shelves Benthic biomass: mass of living organisms on sea floor Matches distribution of chlorophyll in surface waters Distribution is affected by surface ocean currents

Communities on Rocky Shores Epifauna attached to substrate (e.g., marine algae) Move over sea floor (e.g., crabs, snails) Organimsm adaptions to rocky shore adverse conditions Drying out during low tide Ability to seek shelter or withdraw into shells Thick exterios or exoskeleton to prevent water loss External surfaces covered with rock or shell fragments to prevent water loss Physiologically adapted to periodic drying out.

Strong wave activity In algae: strong holdfasts to prevent being washed away In animals: seeking shelter or employing stron attachment threads, biological adhesives, a muscular foot, multiple legs, or hundreds of tube feet to allow them to attach firmly to the bottom In both: hard structures adapted to withstand wave energy; clustering closely together Predators occupy area during low tide/high tide Firm attachment of body parts, including a hard shell Strining cells Camouflage Inking response Ability to break off body parts and regrow them later (regenerative capability) Difficulty finding mates for attached species Release of large numbers of eggs/sprem into the water column during reproduction Long organs to reach others for sexual reproduction Rapid changes in temperature, salinity, PH and oygen content Ability to withdraw into shells to minimize exposure to rapid changes in enviormental onditions Ability to exist in varied temperature, salinity, pH, and low-oxygen environments for extended periods Lack of space or attachment sites Overtake another organism's space Attach to other organisms Planktonic larval forms that inhabit new areas, which limits parental and offspring competition for the same space.

Interidal Zonation Spray zone (supratidal zone): above spring tide zone Organisms avoid drying out Many animals have sells Few species of marine alage Includes periwinkle snail and rock louse Interidal zone high tide zone: relatively dry Animals have shells to avoid drying out Marine algae: rock weeds with thick cell walls Rock weeds colonize first Sessile animals establish later Barnacles and mussels Midle tide zone: covered by all high tides/exposed by all low tides More types of marine algae Soft-bodied animals Barnicales and mussels Carniorous snails and starfish Sea aneones: stinging nematocysts on tenticles poison prey Hermit crabs armored claws and upper body Soft abdomen inhabit abandoned shells Sea urchins Five-toothed mouth

Hard spheical shell Spines for protection Low tide zone: usually wet Abundant alae and surf grass Many animals hidden by seaweed and sea grass Various shore crabs Scavengers keep shore clean hide in rock cracks during day Feed on algae at night Hard exoskeleton prevents rapid dehydration

Communities along sediment-covered shores Sediment size related to wave and curent strength Couse boulder beaches Sand beaches Salt marshes Mud flats Infauna: burrowing animals nearly all large organisms along sandy beaches no stable, fixed surface Burrowing provides more stable enviorment Less risk of temperature extremes and drying out

Sandy Beach Organiss and Adaptions Bivalve mollusks Soft body, hard shell

Eg., claims and mussels Greatest number in low tide regions Annelid worms U-shaped burrow Sand passes through digestive tract Crustaceans Segmented body, hard exoskeleton, and paired jointed limbs Sand crabs common Bury themseleves in sand Echinoderms Spiny skin Five tapeed legs e.g., starfish and heart urchin Meiofauna small, feed on bacteria Polychaetes, mollusks, arthropods, and nematodes Live in sediment from intertidal zone to deep-ocean trenches mud Flats Eelgrass and turtle grass common Bivalves and other mollusks Fidler crabs: males have one small and one large claw

Shallow offshore Ocean Floor Communities Subtidal zone: rocky bottom Kelp Attaches to rocky bottoms with strong holdfast

strips and blades supported by pneumatocysts kelp forests: bed of giant brown bladder kelp and bull kelp Fast growing Highly productive ecosystems Shelter for variety of organisms

Rocky bottom hallow offshore ocean floor communities Lobsters Large, spiny antennae Live in water deeper than 20 meters (65 feet) Scavengers Also feed on live animals Oysters Sessile bivale mollusks Thick shell Food for sea stars, fish, crabs, and snails that bore through shell Oyster beds: empty shells with living generation on top

Coral reefs Reefs: shallow water communities restricted to topics Polyps: individual corals Conditions for Coral Reef Development Warm seawater Sunlight for zooxanthellae: symbiotic photosynthetic microscopic algae in coral tissues Strong waves or currents

Clear seawater: lack of turbidity Normal ocean salinity Hard substrate Symbiosis of Coral and Algae Coral reefs made of algae, mollusks, and foraminifers as well as corals Hematypic coral: mutualistic relationship with algae Algae provide food Corals provide nutrients Other reef animals with symbiotic relationships Mixotrophs: derive part of nutrition from algae Includ coral, foraminifers, sponges, and mollusks Coral Reef Development Typical reefs many kilometers thick Top experiences sunlight corals need bottom was once innsurface waters Charles Darwin noticed reef development stages Hypothesized development related to subsidence of islands The Structure and Distribution of Coral Reefs: Published ideas in 1842 Hypothesis lacked subsidence mechanism later substained with plate tectonics theory Three stages of reef development Fringing Develop among margin of landmass Ideal temperature, salinity, and turbidity conditons not thick or well-developed Subject to influences from landmass Barrier reef

Follows firinging reef stage Well-developed lagoon spereates from landmass Grows upward as landmass subsides Atoll Follows barrier reef stage Reef around volcano subsides and grows verticlly Volcano submerges compelety after millions of years Circular reef left behind. New theory: glacial cycles cause fluctuating sea levels Alternating reefs submergnece and deposition may form atolls faster Coral Reef Zonation Well-developed verticl and horizontal zones Reef slope in deeper waters Less water motion, more delicate corals Reef cret includes buttress zone protecting reef flat with waves. Many fish species inhabit shallow water near reef Reef lagoon habitat for other animals. Importance of Cral Reefs largest structures created by living organisms Great Barrier Reef, Australia, more than 2000 km (1250 miles) long Great diversity of species Important tourists locales Fisheries Reefs protect shorelines Coral reefs and nutrient levels

Fishing, tourist collecting, and sedment influx due to shore development harm coral reefs Sewage dischard and agricultural fertilizers increas nutrients in reef waters Hermatypic corals thrive at low nutiet levels Phytoplankton overwhelm at high nutrient levels Bioerosion of coral reef by algae-eating oragnims.

Crown of Thorns Phenomenon Sea star eats coral polyps Outbreaks (greatly increased numbers) decimate reef Problem in Pacific since 1962 May be part of long-term cycle

Coral Bleaching and Other Diseases Coral bleaching: loss of color in corals Symbiotic zooxanthallae die, leave, or become toxic Bleached coreal lacks nourishment from algae Some causes High surface water temperatures Elevated UV levels Decrease in sunlight-blocking atmospheric particles Pollution Salinity changes Disease Coral Bleaching Events Severe El Nino events

1982-1983 1997-1998 2001-2002 Record bleaching in southeastern Asia, Hawaii, and Caribbean in 2010 2014-2017 multiyear bleaching due to unusally warm sea surface temperatures Affected more than 70% of world coral reefs Linked to climate changes and ocean warming Other Diseases Causes still under investigation Bacteria, viruses, and fungi Human population stressors Increased nutrients and turbidity Environmental stress Diseases includ white plague disease, white band disease, white pox, black band disease, yellow band disease, pathy necrosis, and rapid wasting disease

Coral Reefs in Decline 30% healthy today, down from 41% healthy in 2000 One third of corals: high risk of extinction Threats include hurricanes Global warming Floods Tsunami humans are the greatest threat

Overfishing reef species Runoff with sediment and pollution damages reefs Plastic trash entangles reefs and stresses corals via light deprivation, toxin buildup, and suffocation Atmospheric carbon dioxide Dissolves in seawater and increases acidity Increases air and ocean temperatures an contributs to sea level rise by way of melthing ice caps

Deep-Ocean Floor Comunities Less known about than shallower water communities Expensive to explore the deep Limited oxygen Robotic technology for exploration

Deep Ocean Physical Enviornment Bathal, abyssal, and Hadal zones Abyssal storms affect bottom currents Created by warm and cold core eddies of surface currents Can last weeks light absent below 1000 meters (3300 feet) Temperature usually between -1.8 degrees C (28.8 degrees F) and 3 degrees C (37 degrees F) high oxygen High pressure

Deep Ocean Food Sources and Species Diversity No primary productivity Only 1-3% of euphotic food present Special adaptions for detecting food Species diverstiy equivalent to rain forest

Deep-Sea Hydrothermal Vent Biocommunities Discovery - Alvin in 1977 Galapagos Rift near equator in Pacfic Ocean Complete darkness Water below 2500 meters (8200 feet) Water temperature 8-12 degrees C (46-54 degrees F) Chimney vents and hot acidic water

Deep-Sea Hydrothermal Vent Communities hydrothermal vent biocommunities Organisms previously unknown to science unusally larg for depth in ocean Black smokers: Underwent chimney vents emit sulfides Vents active for years or decades Animal species similar at widely seperated vents Larve drift from site to site "Dead whale hypothesis" Large carcasses may be stepping stone for larvae First Atlantic vents with biocommunities discoverd in 1985

First Indian Ocean vent found in 2000 Vents differ in chemical and geological characteristics Lifespan of Hydrothermal Vents Vents controlled by sporadic volcanic activity Vent may be active for only years to decades Organisms die when vent is inactive Increased volcanic activity can kill organisms Hydrothermal vents and the orgins of life Life on Earth may have originated at hydothermal vents Uniform conditions Presence of archaea bacteria microbes with genes identical to those found in humans

Hydrothermal Vent Species Giant tubeworms Giant clams Giant mussels Crabs Microbial mats Life supported by chemosynthesis Microscopic archaea Thrive on hydration sulfide from vents Manufacture sugar, carbon dioxide, and dissolved oxygen Base of hydrothermal vent food chain

Low-temperature Seep biocommunities

Chemosynthetically support life Hypersaline seeps high salinity Florida Escarpment seeping water from limestone fractures Gulf of Mexico seep from limestone escarpment fractures Sulfide rich waters support diverse biocommunity Hydrocarbon seeps Oil and gas seeps Hydrogen sulfide and/or methane Hydrocarbon seep biocommunities Subduction zone seeps Juan de Fuca plate Folded sedimentary rocks Methane

Beneath the Sea Floor A new frontier Deep biosphere Exists within sea floor Microbes live in pore fluids Might represent much o Earth's toatl biomass...