Bibliography
Fernandez-Leborans, G., and Gabilondo, R., 2006. Inter-annual variability of the epibiotic community on Pagurus bernhardus from
Scotland. Estuarine and Coastal Shelf Science, 66, 35–54.
Laudien, J., and Wahl, M., 2004. Associational resistance of fouled
blue mussels (Mytilus edulis) against starfish (Asterias rubens)
predation: relative importance of structural and chemical properties of the epibionts. Helgoland Marine Research, 58, 162–167.
Cross-references
Benthic Ecology
ESTUARINE BEACHES
C. Scott Hardaway, Jr.
1
, Donna A. Milligan
1 and
Lyle Varnell
2
1
Virginia Institute of Marine Science, College of
William & Mary, Gloucester Point, VA, USA
2
Office of Research and Advisory Services, Virginia
Institute of Marine Science, College of William & Mary,
Gloucester Point, VA, USA
Synonyms
Littoral drift; Littoral transport; Longshore transport
Definition
Estuarine Beaches. Estuarine beaches are unvegetated or
partially vegetated sand, gravel, or shell intertidal beaches
in a partially enclosed bay, lagoon, or fjord and similar
features connected to oceans or seas (Nordstrom, 1992).
Introduction
Estuarine beaches include unvegetated or partially vegetated sand, gravel, or shell intertidal beaches in a partially
enclosed bay, lagoon, or fjords and similar features
connected to oceans or seas (Nordstrom, 1992). They are
created by locally generated waves and wave-induced
currents along estuarine shorelines around the world in a
variety of coastal settings, fetch exposures, and tide ranges.
Fetch is the distance over open water that wind can blow
and generate surface waves. World-wide, many types of
bays with beaches occur; this document is intended to
describe short-fetch, intertidal beaches not typically found
on lakes or on the ocean. While similarities certainly exist,
this document does not describe shorelines that may be
sheltered from the ocean but are still high energy or shorelines that are relatively low energy but have long fetches.
While estuarine beaches are similar to their ocean counterparts in recreational and ecosystem services, they tend
to be smaller in dimension. Ecosystem services are the
benefits resulting from the resources and processes that
are supplied by ecosystems. The function and dimension
of a beach are influenced by wave action, and the physical
type of sediment will vary depending on the geologic
setting. Beaches can extend shoreward from the location
of significant wave reworking below the low tide line to
the landward limit of wave reworking during storms. In
developed estuarine environments where beaches may
owe their origin, dimensions, and some of their surface
characteristics to human action, this definition is still valid
because the beaches are freely worked by waves and
wave-induced currents (Nordstrom, 1992).
Physical processes
A sufficient volume of sediment is necessary for beach
development. The sediment is derived from eroding
fastland banks or from fluvial flow. Bank sediments typically consist of fine-grained silt and clay as well as sand
and gravel. Sand is defined as grains sized between 0.1
and 2.0 mm (Folk, 1980). As a bank erodes, the material
slumps to the base, and wave action winnows out the finer
sediments and reshapes the coarser material into a beach
(Hardaway and Byrne, 1999). While most of the material
on a beach tends to be sand-sized particles, coarser
sediments consisting of shells, gravels, pebbles, or even
cobbles can be deposited as a beach feature on the foreshore. The sand may be predominantly terrigenous quartz
in mid- to upper latitude settings and calcium carbonate in
more tropical settings. Calcium carbonate beaches are
sourced by reworking of offshore coral reefs.
In a typical small estuary, beaches can exist
adjacent to the fastland banks and/or marsh shorelines
(Figure 1: Top). When erosion-resistant fastland banks
occur, pocket beaches may form between headlands.
Pocket beaches may also form between coastal structures
(Figure 1: Middle). Because sand can be transported
through the inlet, beaches can occur just inside the estuary.
Superposed beaches, sandy material above a vegetated
intertidal zone, can occur in areas with larger tide ranges.
Shoreline orientations can differ greatly over short distances, causing great differences in exposure to dominant
winds which will isolate beach segments and limit
longshore sediment exchanges. This will result in beach
sediments that closely resemble local source materials
(Nordstrom and Jackson, 2012).
Estuarine beaches can occur along shorelines with fetch
exposures from less than 100 m in small creeks to the
length of the estuary. While most exist along fetch-limited,
relatively low wave energy coasts, exceptions may occur
along more open reaches of a bay or lagoon which experience larger waves due to their proximity to the open ocean.
Along fetch-limited coasts, fetch distance, rather than
wind duration, limits wave generation. Ocean waves can
enter through an inlet and influence shorelines many kilometers into an estuary; however, ocean waves tend to lose
much of their energy through refraction or breaking, and
their influence decreases the farther they travel into the
estuary (Nordstrom, 1992). In fetch-limited environments,
wave heights generated by local winds depend principally
on wind conditions (speed, duration, and direction) and
ESTUARINE BEACHES
243
Fernandez-Leborans, G., and Gabilondo, R., 2006. Inter-annual variability of the epibiotic community on Pagurus bernhardus from
Scotland. Estuarine and Coastal Shelf Science, 66, 35–54.
Laudien, J., and Wahl, M., 2004. Associational resistance of fouled
blue mussels (Mytilus edulis) against starfish (Asterias rubens)
predation: relative importance of structural and chemical properties of the epibionts. Helgoland Marine Research, 58, 162–167.
Cross-references
Benthic Ecology
ESTUARINE BEACHES
C. Scott Hardaway, Jr.
1
, Donna A. Milligan
1 and
Lyle Varnell
2
1
Virginia Institute of Marine Science, College of
William & Mary, Gloucester Point, VA, USA
2
Office of Research and Advisory Services, Virginia
Institute of Marine Science, College of William & Mary,
Gloucester Point, VA, USA
Synonyms
Littoral drift; Littoral transport; Longshore transport
Definition
Estuarine Beaches. Estuarine beaches are unvegetated or
partially vegetated sand, gravel, or shell intertidal beaches
in a partially enclosed bay, lagoon, or fjord and similar
features connected to oceans or seas (Nordstrom, 1992).
Introduction
Estuarine beaches include unvegetated or partially vegetated sand, gravel, or shell intertidal beaches in a partially
enclosed bay, lagoon, or fjords and similar features
connected to oceans or seas (Nordstrom, 1992). They are
created by locally generated waves and wave-induced
currents along estuarine shorelines around the world in a
variety of coastal settings, fetch exposures, and tide ranges.
Fetch is the distance over open water that wind can blow
and generate surface waves. World-wide, many types of
bays with beaches occur; this document is intended to
describe short-fetch, intertidal beaches not typically found
on lakes or on the ocean. While similarities certainly exist,
this document does not describe shorelines that may be
sheltered from the ocean but are still high energy or shorelines that are relatively low energy but have long fetches.
While estuarine beaches are similar to their ocean counterparts in recreational and ecosystem services, they tend
to be smaller in dimension. Ecosystem services are the
benefits resulting from the resources and processes that
are supplied by ecosystems. The function and dimension
of a beach are influenced by wave action, and the physical
type of sediment will vary depending on the geologic
setting. Beaches can extend shoreward from the location
of significant wave reworking below the low tide line to
the landward limit of wave reworking during storms. In
developed estuarine environments where beaches may
owe their origin, dimensions, and some of their surface
characteristics to human action, this definition is still valid
because the beaches are freely worked by waves and
wave-induced currents (Nordstrom, 1992).
Physical processes
A sufficient volume of sediment is necessary for beach
development. The sediment is derived from eroding
fastland banks or from fluvial flow. Bank sediments typically consist of fine-grained silt and clay as well as sand
and gravel. Sand is defined as grains sized between 0.1
and 2.0 mm (Folk, 1980). As a bank erodes, the material
slumps to the base, and wave action winnows out the finer
sediments and reshapes the coarser material into a beach
(Hardaway and Byrne, 1999). While most of the material
on a beach tends to be sand-sized particles, coarser
sediments consisting of shells, gravels, pebbles, or even
cobbles can be deposited as a beach feature on the foreshore. The sand may be predominantly terrigenous quartz
in mid- to upper latitude settings and calcium carbonate in
more tropical settings. Calcium carbonate beaches are
sourced by reworking of offshore coral reefs.
In a typical small estuary, beaches can exist
adjacent to the fastland banks and/or marsh shorelines
(Figure 1: Top). When erosion-resistant fastland banks
occur, pocket beaches may form between headlands.
Pocket beaches may also form between coastal structures
(Figure 1: Middle). Because sand can be transported
through the inlet, beaches can occur just inside the estuary.
Superposed beaches, sandy material above a vegetated
intertidal zone, can occur in areas with larger tide ranges.
Shoreline orientations can differ greatly over short distances, causing great differences in exposure to dominant
winds which will isolate beach segments and limit
longshore sediment exchanges. This will result in beach
sediments that closely resemble local source materials
(Nordstrom and Jackson, 2012).
Estuarine beaches can occur along shorelines with fetch
exposures from less than 100 m in small creeks to the
length of the estuary. While most exist along fetch-limited,
relatively low wave energy coasts, exceptions may occur
along more open reaches of a bay or lagoon which experience larger waves due to their proximity to the open ocean.
Along fetch-limited coasts, fetch distance, rather than
wind duration, limits wave generation. Ocean waves can
enter through an inlet and influence shorelines many kilometers into an estuary; however, ocean waves tend to lose
much of their energy through refraction or breaking, and
their influence decreases the farther they travel into the
estuary (Nordstrom, 1992). In fetch-limited environments,
wave heights generated by local winds depend principally
on wind conditions (speed, duration, and direction) and
ESTUARINE BEACHES
243