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Intertidal Ecology. Rocky Shores Sandy Shores: sandy beaches Muddy Shores: mud flat. Divisions of Ocean environment. Where? Who? What are they doing there?. Why did these students have to stand in water to do the work?. Mixed, semidiurnal, and diurnal tide curves. Intertidal Ecology.

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Intertidal ecology

Intertidal Ecology

Rocky Shores

Sandy Shores: sandy beaches

Muddy Shores: mud flat






The intertidal zone is the zone between the highest and lowest tides

Highest tide

Lowest tide

Intertidal

Flat

Subtidal zone


Characteristics of the intertidal zones
Characteristics of the intertidal zones lowest tides

  • Flood and ebb tides

  • Water-air alternative exposure

  • Rhythmic

  • Rich diversity and density within a small area



Rocky shore ecology

Rocky Shore Ecology lowest tides

Zonation

Factors affecting zonation

Physical Environmental Conditions

Biological Interactions


Typical Rocky intertidal zonation patterns(Pacific) lowest tidesZonation: Predictable distinctive distribution pattern of marine organisms through intertidal zone



Zonation of major species on rocky shores. The figure is a general scheme of common animals and algae found in eastern North America. Details will differ for specific locations.


Classification of zones in all habitat type ricketts et al 1985
Classification of zones in all habitat type (Ricketts et al., 1985)

  • Zone 1: uppermost horizon: Highest reach of spray and storm waves -- the mean of all high tides: the splash, spray, supralittoral, or Littorina zone

  • Zone 2:high intertidal: Mean high water -- a bit below mean sea level: the home of barnacles and other animals tolerating more air than water

  • Zone 3: Middle intertidal: about mean higher low water -- mean low water

  • Zone 4:Low intertidal: normally uncovered by minus tides only. This zone can be examined during only a few hours in each month


Factors modifying zonation of rocky shore

Abiotic al., 1985)

Wave action and tidal range

Desiccation

Heat stress

Salinity

reduced feeding time

DO and gas exchange

Biotic

Larval settlement

Intra- and interspecific competition

Predation and grazing

Physiological tolerance and adaptation

behavioral pattern, mobility

Factors modifying zonation of Rocky shore


Exposure-shelter diagram for Hong Kong shores. The range of the six litterine species are superimposed. 1. Nodilittorina pyramidalis; 2. Nodilitorina millegrana; Peasiella sp.; 4. Littorina brevicula; 5. Littorina scabra; 6. Littorina melanostoma.


Physical conditions of rocky intertidal areas

Physical conditions of rocky intertidal areas the six litterine species are superimposed. 1.

Tides-Periodical change the organisms' living environments

Temperature-desiccation (could be fatal), particular in tropic region

Wave action--exerts the most influence on organisms and communities


Physical conditions of rocky intertidal areas con t
Physical conditions of rocky intertidal areas (con’t) the six litterine species are superimposed. 1.

  • Wave action (con’t)

    • mechanical effect--smash and tear away objects;

    • acts to extend the limits of the intertidal zone by throwing water higher on the shore (splashing allows the marine organisms to live higher in exposed wave-swept areas than in sheltered areas within the same tidal range

    • change the topography of intertidal area by move substratum around

    • mix atmospheric gases into the water--increasing the oxygen content


Physical conditions of rocky intertidal areas con t1
Physical Conditions of Rocky intertidal areas (con’t) the six litterine species are superimposed. 1.

  • Salinity-the intertidal may be exposed at low tide and subsequently flooded by heavy rains or runoff from heavy rains --- either would sense severe problems

  • Substratum topography - grain size would change

  • pH and nutrients (not very important)


General distribution patterns
General distribution patterns the six litterine species are superimposed. 1.

  • Random distribution: distribution of organisms can be explained by random chance

  • Even distribution: organisms occur in an even manner

  • Patchiness: Organisms occur in isolated groups within a larger contiguous suitable habitat


Adaptation
Adaptation the six litterine species are superimposed. 1.

  • Adaptation to desiccation (water loss)

    • Move to moist place or under the moist cover (crabs & snails)

    • Tolerate high % water loss (Fucus, Porphyra, Enteromorpha, up to 60-90%)

    • Reduce water loss by close shells (snails, barnacles, limpets’ home scar)

    • Build shield to cover up (sea anemone or sea urchin covered with shell fragments)




Many snails of the genus in intertidal organisms.Littorina live high in the intertidal zone. When exposed, the snail protects itself from desiccation by pulling back into the shell and covering the opening with the operculum. First it secretes a mucous thread that attaches the shell to the rock.


Adaptation1
Adaptation in intertidal organisms.

  • Adaptation to high temperature (heat)

    • Temperature shock can

      • affect, metabolic and biochemical processes, such as enzyme function and oxygen demands.

      • retard cellular activities, such as ciliary motion.

      • inhibit behavioural activities, such as feeding & protection against predators.

      • inhibit reproductive behaviour, such as egg laying and copulation.


Adaptation2
Adaptation in intertidal organisms.

  • Adaptation to high temperature (heat)

    • Reduce heat gain from the environment.

      • Have a relatively large body size (less surface area relative to volume and less area for gaining heat, taking longer to heat up). (Littorina spp larger at high tidal zone)

      • Reduce the area of body tissue in contact with the sbustrate (difficult to achieve – swept off by waves)

    • Increase heat loss from the body

      • Elaborated shell ridges & sculptures acting as heat radiators (snails)

      • Light-colored body (gain and lost heat slowly)

      • Water evaporation (holding extra water in mantle cavity of barnacles, limpets– exceeds the amount the animal needs to survive desiccation)



Adaptation3
Adaptation and sculptured, light shells.

  • Adaptation to wave action (smashing and tearing effects)

    • Limitation of size and shape (relatively small, squat bodies with streamlined shapes to minimize the exposure to the lift and drag of wave forces)

    • Flexible and bending (seaweed)

    • Firm attachment by holdfast (algae), cemented shell

    • Temprary attachments by byssal threads (which can be borken and remade)

    • Thick shells, no delicate sculpturing

    • Large foot to clamps to the substrata

    • Seek shelters (crabs)


The distribution of barnacles from shelter to exposure (from Tain Tam to Cape D’Aguilar). 1. Balanus tintinnabulum volcano; 2. Tetraclita squamosa; 3. Pollicipes mitella; 4. Balanus variegatus variegatus; 5. Balanus amphitrite amphitrite; 6. Balanus albicostatus albicostatus; 7. Euraphia withersi. A detail of the numbers and fusion of the valves of the principal genera are also given.


Algal formation of exposed vs sheltered coasts
Algal formation of exposed vs. sheltered coasts Tain Tam to Cape D’Aguilar). 1. Balanus tintinnabulum volcano; 2. Tetraclita squamosa; 3. Pollicipes mitella; 4. Balanus variegatus variegatus; 5. Balanus amphitrite amphitrite; 6. Balanus albicostatus albicostatus; 7. Euraphia withersi. A detail of the numbers and fusion of the valves of the principal genera are also given.


Adaptation4
Adaptation Tain Tam to Cape D’Aguilar). 1. Balanus tintinnabulum volcano; 2. Tetraclita squamosa; 3. Pollicipes mitella; 4. Balanus variegatus variegatus; 5. Balanus amphitrite amphitrite; 6. Balanus albicostatus albicostatus; 7. Euraphia withersi. A detail of the numbers and fusion of the valves of the principal genera are also given.

  • Respiration (gills highly susceptible to desiccation in air)

    • Enclose in a protective cavity to prevent them from drying (molluscs)

    • Reduction of the gill and formation of a vascularized mantle cavity

    • Mantel tissue act as lung for aerial respiration (barnacles)

    • Close up (operculum) or clamp down (chitons and Limpets) to reduce gaseous exchange

    • Remain quiescent druing low tide to conserve oxygen and water


Adaptation5
Adaptation Tain Tam to Cape D’Aguilar). 1. Balanus tintinnabulum volcano; 2. Tetraclita squamosa; 3. Pollicipes mitella; 4. Balanus variegatus variegatus; 5. Balanus amphitrite amphitrite; 6. Balanus albicostatus albicostatus; 7. Euraphia withersi. A detail of the numbers and fusion of the valves of the principal genera are also given.

  • Salinity (flood by fresh water or expose to extremely high salinity)

    • Osmoconformers: organisms without mechanisms to control the salt content of their body fluids – using same adaptation as to prevent desiccation.

    • Osmoregulators: organisms with physiological mechanisms to control the salt content of their internal fluids


Causes of patchiness in algae on rocky shores. (A) Sweeping action of algal fronds. (B) Irregular spatial and temporal distribution of grazers. (C) Fluctuations in recruitment. (D) Refuge from grazing provided by pits and cracks in rock. (E) Escape of spoelings from grazers.


Biological factors controlling rocky intertidal zonation
Biological factors controlling rocky intertidal zonation action of algal fronds. (B) Irregular spatial and temporal distribution of grazers. (C) Fluctuations in recruitment. (D) Refuge from grazing provided by pits and cracks in rock. (E) Escape of spoelings from grazers.

  • Competition (barnacles as examples)

  • Predation (starfish, mussels, and barnacles)

  • Grazing (sea urchin on seaweed)

  • Larval settlement

  • Interaction among the controlling factors – community ecology


Biological factors controlling rocky intertidal zonation1
Biological factors controlling rocky intertidal zonation action of algal fronds. (B) Irregular spatial and temporal distribution of grazers. (C) Fluctuations in recruitment. (D) Refuge from grazing provided by pits and cracks in rock. (E) Escape of spoelings from grazers.

  • Competition (barnacles as examples)

  • Predation (starfish, mussels, and barnacles)

  • Grazing (sea urchin on seaweed)

  • Larval settlement

  • Interaction among the controlling factors – community ecology


Interspecies competition action of algal fronds. (B) Irregular spatial and temporal distribution of grazers. (C) Fluctuations in recruitment. (D) Refuge from grazing provided by pits and cracks in rock. (E) Escape of spoelings from grazers.

Intertidal zonation as a result of the interaction of physical and biological factors.The larvae of two barnacles, Chthamalus stellatus and Balanus balanoides, settle out over a broad area. Physical factors, mainly desiccation, then act to limit survival of B. balanoides above mean high water of neap tides. Competition between B. balanoides and C. stellatus in the zone between mean tide and mean high water of neap tides then eliminates C. stellatus.



Controlling factors
Controlling factors intertidal barnacles

  • High tidal zone

    • Chthamalus stelatus settled here

    • Semibalanus balanoides have no sufficient tolerance to drying and high temperatures.

  • Mid tidal zone

    • Chthamalus stelatus settled here but was overgrew, uplifted or crushed by Semibalanus balanoides


The main groups of algal grazers at different intertidal zones in temperate and tropical systems
The main groups of algal grazers at different intertidal zones in temperate and tropical systems.

Grazing



Interaction of predation and physical factors in establishing the zonation of the dominant intertidal organisms on the rocky shores


Interactions among mussels ( establishing the zonation of the dominant intertidal organisms on the rocky shoresMytilus), barnacles, and their predators on the northwester Pacific coast of North America, which allow barnacles to persist in the intertidal zone.

Predation/competition




Rocky intertidal food web
Rocky intertidal food web. bed in the absence of


Sandy and Muddy Shores bed in the absence of

Sandy

Muddy

1. Shape up of beaches

Larger

  • Sediment size

  • Wave action

  • Slope

Stronger

Slopy

Exposed

2. Surroundings

  • Exposed vs protected

  • Oceanic vs semi-enclosed waters, estuaries or wetlands

  • Seasonal vs non-seasonal

Oceanic

Seasonal

3. Sediment movement

  • Swash and backwash

  • Longshore transport

Applicable


Sandy bed in the absence of

Muddy

Larger

4. Physical conditions of intertidal flats

  • Grain size

  • Interstial space

  • Pore water

  • Water retention

Larger

Greater Fluctuation

Weaker

ShallowerAnoxic

5. Biogeochemical conditons

  • Oxygen

  • Organic matter

  • RPD

Rich

Strong, Shallower

6. Organisms

High

  • Diversity

  • Abundance

  • Production

Large

High


Longshore Transport Processes bed in the absence of

So sand downcast in a zigzag path

Path of sand on beach

returns straight down the beach

Water moves on shore at an angle

Net Transport of sand

Shoreline

Surf zone

Longshore current

Longshore transport


Some terms
Some terms bed in the absence of

  • Swash: water running up a beach after a wave breaks; this action carries particles with it, which may cause accretion of the beach if the particles remain there

  • Backwash: water flowing back down the beach; this action removes particles from the beach, depending on the particle size

  • Slope: the slope of a beach is the result of the interaction between particle size, wave action, and the relative importance of swash and backwash water.

  • Dissipative beach: occurs where wave action is strong but the wave energy is dissipated in a broad, flat surf zone located some distance from the beach surface (gentle swash, fine sediments, gentle slope

  • Reflective beach: occurs where wave action impinges directly on the beach face and the sediment is coarse (no offshore surf zone, wave produce large swashes up the beach face, steep slop). Backwash and swash collide to deposit sediment and wave energy is directed against the face of the shore and reflected off the surface.


Classification of particle sizes
Classification of particle sizes bed in the absence of



Comparison of the physical conditions found in fine grained and coarse grained beaches
Comparison of the physical conditions found in fine-grained and coarse-grained beaches

  • Particle size

  • Slope

  • Water retention

  • Particle retention

  • Surface to volume absorption

  • Oxygen

  • Organisms

High tide

Water drains out at low tide

Low tide

High tide

Water retained at low tide

Low tide




Surface stability of particulate shores. Surf causes a suspension of the particles. Waves 1m in height disturb the sediments to a depth of 8 cm. Burrowing in this shifting substrate is difficult.


A transect of a sand beach showing gradients of water content salinity at low tide
A transect of a sand beach showing gradients of water content, salinity at low tide

<5%

5-10%

10-15%

15-20%

20%

Water edge

Intertidal zone



A transect of a sand beach showing gradients of water content salinity at low tide1
A transect of a sand beach showing gradients of water content, salinity at low tide

O2 saturation

Water edge


Sandy shores
Sandy Shores content, salinity at low tide

A common sense, all public recreational beaches are usually sandy shores.

Sandy shores are usually exposed, poor in nutrients and therefore organisms.

Muddy Shores

Muddy shores usually associated with estuaries and salt marshes, enclosed bays, lagoons, harbours,

Protected from open ocean wave action

Flat

Near sources of fine sediments


Types of organisms in sandy beach
Types of organisms in sandy beach content, salinity at low tide

  • No macroscopic plants occur on open sand beach, but certain ephemeral algae such as Ulva or Enteromorpha may be abundant in protected sand flats

  • No sessile animals such as barnacle and mussels


Types of organisms in sandy beach1
Types of organisms in sandy beach content, salinity at low tide

  • Small benthic diatoms may be present on the sand grains, protected sand flats support a large and diverse microtlora of benthic diatoms, dinoflagellates, and blue-green algae--form brownish or greenish film on the sediment surface.

  • Dominate by polychaetes, bivalves, and crustaceans


Zones of water content on sandy beaches
Zones of water content on sandy beaches content, salinity at low tide



Adaptation of organisms of sandy beach
Adaptation of organisms of sandy beach (B) Moving. (C) Reburial.

  • Burrow deeply -organism is deeper than the depth of d by the passing wave.

  • Burrow quickly - employed by many annelid worms, small clams, burrow quickly as soon as the passing wave has removed the animals from the substrata.


Subsequent morphology changes (B) Moving. (C) Reburial. - To burrow deeper, the clam Tivela stultorum developed heavy shell and long siphons; - To burrow fast, raxor clams of the genus Siliqua have very smooth shells, special ridges on the shell to grip the sediment to aid in penetrating into the substrata, sand dollars have much reduced spines to allow them to burrow them into the sand; sand crabs have a short body with limbs highly modified to dig quickly into wet sand;sand dollars Dendraster excentricus accumulate iron compounds in a special area of their digestive tracts, which serve as a weight belt to keep them down in the presence of wave action.


Adaptation of organisms of sandy beach (B) Moving. (C) Reburial.

Developed special structures to prevent clogging of respiratory surface--intake siphons of sandy beach clams are often fitted with various screens; the antennae of sand crabs held together form a tube to surface through which water enters the branching chamber--densely clothed with closely spaced hairs designed to prevent entrance of sand.






Exposed beaches.

Sheltered

Upper limit of wave spray and splash

Intertidal zone


Organisms beaches.

Types of organisms

Flora: plant community

Fauna: animal community

Epifauna: animals dwelling on the surface of sediment

Infauna: animals dwelling below the surface of sediment

Microfauna: organisms < 0.1 mm

Meiofauna: 0.062 mm - 0.5 mm

Macrofauna: > 1 mm


Organisms beaches.

Adaptations

Burrowing: to construct by tunneling, or digging, e.g. polychaetes,

Tubes: siphon tube, large clams-long siphons to prevent clogging respiration pathway, heavy shell to prevent storms

Mobile: move quickly with passing wave, commonly employed by many annelid worms, small clams, and crustaceans. Eg. Sand crabs populate the world beaches, have a short body with limbs highly modified to dig quickly into wet sand. As soon as they are freed from the substrate by a passing wave, they reburrow quickly again before wave motion carries them offshore


Food sources beaches.

Phytoplankton

Benthic algae (microalgae-diatoms, macroalgae-red algae, green algae, seagrass)

Detritus: small debris of organic matter, from dead organisms

Bacteria


Feeding Types: beaches.

Deposit feeders (by deposit feeding):

Surface deposit feeders

Burrowing deposit feeders

Suspension feeders: filter feeders

Detritus feeders

Scavengers


Mudflat ecology

Mudflat Ecology beaches.

Organisms

Adaptations of organisms

Types of organisms

Feeding Biology


Physical factors of muddy beach
Physical factors of muddy beach beaches.

  • Muddy shores are restricted to intertidal areas completely protected from open ocean wave activity--with no wave action.

    • Muddy shores are located in various partially enclosed bays, lagoons, harbors, and especially estuaries where there is a source of fine-grained sediment particles

    • The slope of mud shores is much flatter than that of sand beaches.


  • More stable than sand substrata and more conducive to the establishment of permanent-burrows.

  • Anaerobic conditions because water in the sediments does not drain away --long retention time for water, coupled with a very poor interchange of the interstitial water with the seawater above and a high internal bacterial population,--complete depletion of the oxygen in the sediments below the first few cm of the surface


  • Between the upper aerobic aver (brown or --yellow) and the lower anaerobic layer (black) there occurs transition zone called-redox potential discontinuity (RPD) layer (grey)

  • Accumulate organic material - an abundant potential food supply for the resident organisms; but abundant small organic particles "raining" down on the mud flat also have the potential to clog respiratory surfaces.


RPD layer— lower anaerobic layer (black) there occurs transition zone called-redox potential discontinuity (RPD) layer (grey) - reduces compounds diffuse upward from below and as soon as oxygen is available, bacteria oxidize these compounds and the oxidized end products including CO2, NO3 and SO4, in turn are incorporated into bacterial biomass and form the basis of new food chains, some compounds diffuse downward below the RPD zone and utilized by the anaerobic bacteria. These bacteria in turn produce more reduced compounds, which complete the cycle; - chemoautotrophic bacteria in the RPD zone oxidize the reduced compounds and fixing CO2 and produce more organic materials.


Aerobic lower anaerobic layer (black) there occurs transition zone called-redox potential discontinuity (RPD) layer (grey): a condition with oxygen for organisms, Oxic

Anaerobic condition: a condition depleted of oxygen, Anoxic.

Redox Potential: reduction-oxidation potential, measured by an electrode. It is positive, meaning oxidizing condition; negative-reduction condition

RPD: redox potential discontinuity

RPD layer: a transition zone between the upper aerobic layer and the lower anaerobic layer, characterized by a rapid change from a positive redox potential (Eh) to a negative potential.

Decomposition of organic matter is:

by aerobic bacteria above RPD

by anaerobic bacteria below RPD

Chemoautotrophic bacteria: obtain energy through the oxidation of a number reduced compounds like H2S to produce organic matter. They are primary producers.


Diagrammatic representation of the physical and chemical characteristics of sediments across the redox discontinuity layer and the biological processes occurring in each


Physical factors of sandy beach
Physical factors of sandy beach characteristics of sediments across the redox discontinuity layer and the biological processes occurring in each

  • Wave action--vary with sites, seasons, as the results:

    • Particle size vary due to the wave actions--where wave action is light, the particles are fine, but where wave action is heavy and strong, the particles are coarse, forming deposits called gravel or shingle rather than sand

    • Water retention--coarse sand and gravel allow water to drain away quickly as the tide retreats while fine sand and retent water longer

    • Organisms in a coarse gravel beach suffer from desiccation

    • Fine sand is more amenable to burrowing than coarse gravel


Physical factors of sandy beach characteristics of sediments across the redox discontinuity layer and the biological processes occurring in each

  • Unstable constantly moving substrata--substrate movement--particles are beingcontinually moved and sorted-- a gradation of particle sizes from fine near low water to coarser at the high tide mark.

  • Since profile and shape of sand beach change so often, few large organisms have the capability of permanently occupying the surface of open sand or gravel beaches

  • Relatively uniformed topographic--the environmental factors such as T'C, desiccation, wave action, insulation act uniformly--change little in the sand

  • Saturated oxygen content


Adaptation of organisms of muddy beach
Adaptation of organisms of muddy beach characteristics of sediments across the redox discontinuity layer and the biological processes occurring in each

  • Burrow into the substrata

  • Form permanent tubes

  • Physical adaptation to live under anaerobic condition burrowing shrimps and clams have haemoglobin with much higher affinity of oxygen; other animals use glycogen stores for anaerobic metabolism.

  • Obtain oxygen-rich surface water and food through various burrows, holes and tubes appear on the surface of -the mud flat


Two common polychaete worms of mud flats: characteristics of sediments across the redox discontinuity layer and the biological processes occurring in eachArenicola (right) in its U-shaped burrow, and Capitella (left) burrowing through the substrate.


Macoma nasuta in the substrate b macoma nasuta feeding with its in current siphon
Macoma nasuta characteristics of sediments across the redox discontinuity layer and the biological processes occurring in each in the substrate. (B) Macoma nasuta feeding with its in-current siphon.


Types of organisms in muddy beach
Types of organisms in muddy beach characteristics of sediments across the redox discontinuity layer and the biological processes occurring in each

  • Epifaunal primary producer--diatom (giving a brownish colour to the surface at low tide, Gracilaria (red algae), Ulva & Enteromorgha (green algae), sea grasses (Zostera) in the lowest tidal levels

  • Infaunal primary producer – large numbers of Chemosynthetic or sulfur bacteria (only abundant organisms found in the anaerobic layers of mud).

  • Dominant macrofaunal groups including polychaetes., bivalves, small and large crustaceans


Nitrogen cycle of a soft bottom marine community
Nitrogen cycle of a soft bottom marine community characteristics of sediments across the redox discontinuity layer and the biological processes occurring in each


What a mess! characteristics of sediments across the redox discontinuity layer and the biological processes occurring in each

So guess who is who in terms of feeding types?


Surface deposit feeders: characteristics of sediments across the redox discontinuity layer and the biological processes occurring in each

A: spionid polychaete

B: protochodate

E: spionid polychaete

Burrowing deposit feeders:

C: paraonid polychaete

D: oligochaete

H: syllid polychaete

I: orbiniid polychaete

J: Nephtyid polychaete

Suspension feeders

G: venerid bivalves

F: haustorid amphipod

K: haustorid amphipod


Generalized food web of a muddy shore
Generalized food web of a muddy shore. characteristics of sediments across the redox discontinuity layer and the biological processes occurring in each


Species richness versus tidal level
Species richness versus tidal level. characteristics of sediments across the redox discontinuity layer and the biological processes occurring in each


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