Temperate Coastal Seas - Temperate Coastal Seas More than...

Temperate Coastal Seas

More than 90% of marine animals are
benthic :
- living in close association with the
seafloor
- living at the interface with the
overlying water
- or are dependent on the
characteristics of each and the
exchange of substances between the
two.
Collectively these organisms are called
Benthos.

The composition of the sea bottom is determined by
•
its constituent materials
•
accumulation of plankton, waste material, and
detritus
•
the activities of organisms that live there

i.e. excavation of burrows
•
the amount of available energy in waves and
currents at the sea surface in shallow waters.
Seabed characteristics

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

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

A benthic lifestyle does not necessarily limit the
geographic of these species.

Some species can hitch rides to new locations.
75% of slow-moving, sedentary, or attached
(sessile) benthic invertebrates extend their
geographic range by broadcast spawning of eggs
and sperm that will result in larvae that are
temporarily planktonic
(=MEROPLANKTONIC).
•
Typically remain planktonic for 2-4 weeks
Larval Dispersal

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

Factors that effect settlement:

bottom type,

bottom texture,

chemical attractants,

current speeds,

sounds,

light, and

presence of conspecific adults
The settled larvae then metamorphose into a juvenile form.
For each extra day the larvae remain in the plankton, they
are exposed to:
-additional threats of predation
-increased pressures of finding food
-more likely currents carry them to unsuitable area
Larval Dispersal

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

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 physiological stress during periods of low tide .
Being out of the water and exposed to air= EMERSION
Being submerged under water = IMMERSION
The bottom substrate (e.g. soft or rocky) and
the effects of the tide are two of the main factors which
effect intertidal communities.
Intertidal Communities

Rocky Shores
Exposure curves for the
Pacific coast of the
United States and the
Atlantic coast of
England
.

Rocky Shores

Generally occur in steep sloping areas without
much sediment e.g. active margins where
geological processes are lifting land

Rocky shores may also occur in areas with
outcrops of hard exposed rock,

Or where the action of the sea has removed
sediment leaving bare rock behind.