Temperate coastal seas

Chapter 8

Temperate Coastal Seas
More than 90% of marine animals are benthic, living in close
association with the seafloor, at the interface with the overlying
water, dependent on the characteristics of each and the exchange
of substances between the two.

Seafloor Characteristics
The composition of the sea bottom is
determined by:
 plankton, wastes, and detritus
 the activities of organisms that live there
 the energy in waves in shallow water
 the energy in currents in shallow water


Fig. 8.1 In coves and bays, refraction of advancing ocean waves
spreads out the wave crests (and their energies) and concentrates
them on headlands and other projecting coastal features.


Fig. 8.2 Particle size ranges for some common sources of marine
sediments. Biogenic particles are shown in blue and terrigenous
particles in tan.

Animal–Sediment Relationships
Benthic animals are either:
 epifaunal, living on the sediment, or
 infaunal, living within the sediment.


Fig. 8.3 Variations in the
average number of species
of several bottom
invertebrate groups from
equal-sized coastal areas in
different latitudes.

Adapted from G. Thorson. Treatise on Marine Ecology
and Paleoecology. Vol. I., Ecology. Geological Society
of America, 1957.


Fig. 8.4 Sandstone
erosion pits created by
the rasping actions of
small chitons.


Suspension
and filter
feeders obtain
their food from
passing waters
Fig. 8.5 Barnacle, Balanus, with its
feathery filtering appendages extended.

© Sanamyan/Alamy Images


Fig. 8.6 A phalanx of sea
stars, Pisaster, crops a
bed of mussels.

Photo by Dave Cowles, Rosario Marine Invertebrates website http://rosario.wallawalla.edu/inverts


Fig. 8.7 A large snail grazing on seaweed.
© Christopher Poliquin/ShutterStock, Inc.

Larval Dispersal
 About 75% of slow-moving, sedentary, or attached
animals extend their geographic range via
broadcast spawning of eggs and sperm that will
result in larvae that are temporarily planktonic (or
meroplanktonic).

Larval Dispersal

Fig. 8.8 Meroplanktonic larval forms (top) and adult forms (bottom)
of some common benthic animals: (a) polychaete worm,
(b) sea urchin, (c) crab, and (d) snail.

Larval Dispersal

Fig. 8.9 Typical duration of planktonic
existence for four common groups of
marine benthic invertebrates.

Adapted from G. Thorson. Oceanography (1961): 455-474.

Larval Dispersal
 Many factors influence meroplanktonic larvae to
settle on the seafloor and metamorphose into
juveniles:
•
•
•
•
•
•
•

bottom type
bottom texture
chemical attractants
current speeds
sounds
light
presence of conspecific adults

Larval Dispersal

Fig. 8.10 Several major environmental factors that influence the
selection of suitable bottom types by planktonic larvae.

Larval Dispersal

Fig. 8.11 Generalized development pattern for planktonic larvae,
illustrating available options in response to food, substrate, or other
environmental cues.

Larval Dispersal

Fig. 8.2 A scanning electron micrograph of a
sea urchin egg with numerous sperm cells.

© Dr. David Phillips/Visuals Unlimited

Intertidal Communities
 Daily fluctuations in tidal heights result in an
intertidal, or littoral, zone forming on all shorelines,
regardless of slope or texture.
 This zone is inhabited by species of marine origin
that experience, and somehow tolerate,
physiological stress during periods of low tide.


Fig. 8.14 An infrared aerial photograph of a portion of the
Oregon coast with protected coves, exposed headlands, sandy
beaches, and offshore rocky reefs. Note the complex refraction
of surface waves around the offshore reefs.

Courtesy U.S. Geological Survey

Fig. 8.15 (a) Young red mangroves colonize a tropical shoreline.
(b) Their network of prop roots traps sediment and detritus.

© FloridaStock/ShutterStock, Inc.

Courtesy of OAR/National
Undersea Research Program
(NURP)/NOAA


Fig. 8.16 The relative force of breaking waves
over a range of wave heights for several
different intertidal animals.

Adapted from Denny, M. W. Limnology and Oceanography 30 (1985): 1171-1187.

Rocky Shores
 Distance from low water is correlated with
variations in physical and biological
stresses, resulting in distinct horizontal
bands of zonation.

Rocky Shores

Fig. 8.17 Magnified cross-section of a lichen with
algae cells (dark spots) embedded in fungal
filaments.

Fig. 8.18 Snails and limpets grazing on sparsely
distributed algae growing along the edge of a tidal
pool.
© Wildlife Pictures/age fotostock

Rocky Shores
 The upper intertidal of rocky shorelines
hosts organisms that suffer from frequent
desiccation and punctuated food supplies.

Fig. 8.19 Stunted acorn
barnacles, Chthamalus,
survive in the shallow
depression of carved
letters.

Rocky Shores

Fig. 8.20 Planktonic and early benthic stages of the barnacle Balanus:
(a) nauplius stage, (b) cypris stage, and (c) early benthic stage.


Fig. 8.21 The limiting effects of
desiccation and competition on the
vertical distribution of two species of
intertidal barnacles, Chthamalus (blue
bars) and Balanus (green bars).

Adapted from Connell, J. H. Ecology 42 (1961): 710-723.

Rocky Shores
 The middle intertidal is more densely
populated with species more troubled by
competition for food and space than physical
limitations of the environment.


Rocky Shores

Fig. 8.22 The aggregate sea anemone, Anthopleura
elegantissima. Exposed individuals (upper right) have
retracted their tentacles to avoid dessication.

© Danita Delimont/Alamy Images


Fig. 8.23 Close-up view of mussels, Mytilus, attached
to rocks in the middle intertidal.

Fig. 8.24 algal species exposed during low tides
use thickened cell walls to prevent water loss.
© Carsten Medom Madsen/ShutterStock, Inc.


Fig. 8.25 Tightly packed barnacles compete for space along the intertidal.
Photo by Dave Cowles, Rosario Marine Invertebrates website http://rosario.wallawalla.edu/inverts


Fig. 8.26 Sea stars, Pisaster, aggregating
near the low tide line to avoid dessication.

© Charles A. Blakeslee/age fotostock


Fig. 8.27 General pattern of succession through time on temperate rocky shores. The blue curve indicates a
relative biomass.

Rocky Shores
 The lower intertidal hosts a diversified assemblage
of plants and animals that are exposed to air for only
a short period of time each day.

Fig. 8.28 Surf grass covers rocks and helps to keep
intertidal organisms moist during low tide.
© Weldon Schloneger/ShutterStock, Inc.


Fig. 8.29 The green anemone,
Anthopleura xanthogrammica.
© Weldon Schloneger/ShutterStock, Inc.

Fig. 8.30 An eolid nudibranch with long finger-like
cerata projecting from its dorsal surface.
© Kerry L. Werry/ShutterStock, Inc.


Fig. 8.31 A scallop flaps its valves (shells) vigorously to jet away from a
predatory sea star.
© Marevision/age fotostock


Fig. 8.32 Vertical zonation
patterns on a 3-m-high rock on
the coast of Oregon.

Sandy Beaches
 Sandy beaches and muddy shores are
depositional environments characterized by
deposits of unconsolidated sediments and
accumulations of detritus.

Intertidal Communities: Sandy Beaches

Fig. 8.33 Sandy beach zonation along the East Coast of the United States. The
species change rapidly from the portion permanently under water at left to the dry
part of the beach above high tide at the right.
Sea cucumber: Courtesy of Dr. James P. McVey/NOAA Sea Grant Program; Olive shell: Courtesy of Image*After; Blue crab: ©
APaterson/ShutterStock, Inc.; Flounder: Courtesy of NW Fisheries Science Center/NOAA; Sand dollar and Cockle: Photodisc; Clam:
Courtesy of Dr. Roger Mann, VIMS/NOAA; Bristle worm and Land crab : Courtesy of NOAA; Amphipod: Courtesy of M. Quigley,
GLERL/NOAA, Great Lakes Environmental Research Laboratory.


Fig. 8.36 A few examples of the interstitial fauna of sandy beaches. Each is of a
different phylum, yet all exhibit the small size and worm-shaped body characteristic
of meiofauna: (a) polychaete, Psammodrilus; (b) a copepod, Cylindropsyllis; (c) a
gastrotrich, Urodasys; and (d) a hydra Halammohyra.
Adapted from S. K. Eltringham. Life in the Mud and Sand. Crane, Russak, 1972.


Fig. 8.37 Grunion, Leuresthes,
spawning in the sands of a
southern California beach.
Males coil around females that
dig themselves into the sand to
deposit their eggs.

© Visual&Written SL/Alamy Images


Fig. 8.38 Predicted tide heights for a 3-week period at San Diego, California. Spring tides
appropriate for grunion spawning occur on days 6, 7, and 8 (pointers at left). Nine and 10
days later, the next set of spring tides (pointers at right) wash the eggs from the sand, and
they hatch. Shaded portions indicate night hours.

Oiled Beaches
 Because oil is less dense than seawater,
when it is spilled (intentionally or not), most
of it ends up in intertidal zones.

Oiled Beaches

Fig. 8.39 An oil-soaked bird struggles to survive after an oil spill.
Photo courtesy of the Exxon Valdez Oil Spill Trustee Council

Oiled Beaches

Fig. 8.40 Scores of dead birds litter a beach after an oil spill.

Oiled Beaches

Fig. 8.41 Workers use highpressure hot water to clean an
oiled beach.


Shallow Subtidal Communities

Fig. 8.42 A series of soft-bottom benthic communities found at different depths in Danish seas, including
bivalve mollusks (1, 2, 3, 7, 8, 9, 10, 19), polychaete worms (6, 15), scaphopod mollusks (16), ophiuriod
echinoderms (12,13), echinoid echinoderms (14), and arthropod crustaceans (18).


Fig. 8.43 Diagram
showing the close
similarity in composition of
soft-bottom communities
in the northeast Pacific
and the northeast Atlantic.

Adapted from Adapted from G. Thorson. Treatise on Marine Ecology and Paleoecology. Vol. I., Ecology. Geological Society of
America, 1957.


Fig. 8.44 Several species of kelp-community
fishes sheltering near giant kelp, Macrocystis.
© Galina Barskaya/ShutterStock, Inc.

Below the effects of waves and tides, kelp
communities dominate in temperate areas.

Fig. 8.45 General structure of a West Coast kelp forest, with a complex
understory of plants beneath the dominant Macrocystis or Nereocystis.


Fig. 8.46 Trophic relationships of some dominant members of a southern
California kelp community.


Fig. 8.47 Trophic relationships of the common
members of a New England kelp community.


Fig. 8.48 Extent of areas changed or
degraded by four major sewage
outfalls in the California Bight, 19781979.

Data from A. J. Mearns. Marine Environmental Pollution. Elsevier, 1981.


Fig. 8.49 Graphs showing the reduction in discharged total suspended solids
(TSS) for the past two decades at the four major sewage outfalls in the California
Bight.
Data from Steinberger and Schiff, 2002.

Temperate coastal seas

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