SANDFLAT
Jorge Manuel López-Calderón
1
, Alf Meling
2 and
Rafael Riosmena-Rodríguez
1
1
Programa de Investigación en Botãnica Marina,
Departamento Académico de Biología Marina,
Universidad Autónoma de Baja California Sur, La Paz,
Baja California Sur, Mexico
2
Universidad Autónoma de Sonora, Hermosillo, Sonora,
Mexico
Synonyms
Mudflat; Tidal flat
Definition
A sandflat is an extension of unconsolidated sediment
located preferentially in the lower intertidal zone. It is an
unstable area characterized by the constant resuspension
of sediment by tidal flood and ebb currents. Tidal forces
predominate over other hydrodynamic processes, forming
well-sorted sand deposits.
Hydrodynamics
The amount of mud found in the sediment of a sandflat
is determined by the bed slope, the amount of fine sediments derived from land, and the strength of the current.
The sandflat-mudflat threshold is determined by the aforementioned factors. Finer muddy sediments accumulate
during neap tides, while coarser sandy sediments accumulate during spring tides. Hydrodynamic conditions of
sandflats preclude development of submerged aquatic
vegetation; however, there are important resident communities of burrowing invertebrates (worms, bivalves, crustaceans) that are fundamentally important for local trophic
networks and the recycling of nutrients. Sandflats can be
found adjacent to other types of habitats, such as
saltmarshes located in the upper intertidal zone (Perillo,
1996; Schwartz, 2005; Perillo et al., 2009).
Bibliography
Perillo, G. M. E. (ed.), 1996. Geomorphology and Sedimentology of
Estuaries. Amsterdam: Elsevier.
Perillo, G. M. E., Wolanski, E., Cahoon, D. R., and Brinson, M. M.
(eds.), 2009. Coastal Wetlands: An Integrated Ecosystem
Approach. Amsterdam: Elsevier.
Schwartz, M. L. (ed.), 2005. Encyclopedia of Coastal Science.
Dordrecht: Springer.
Cross-references
Sandbanks
Sediment Grain Size
Sediment Transport
Tidal Flat
Tidal Flat Salinity Gradient
SEABIRDS
Joanna Burger
Department of Cell Biology and Neurosciences, Ecology,
Evolution and Natural Resources, Department of Marine
and Coastal Sciences, Environmental and Occupational
Health Sciences Institute, Rutgers University, Piscataway,
NJ, USA
Synonyms
Estuarine birds; Marine birds; Pelagic birds
Definitions
Seabirds. Birds that live primarily on the oceans of the
world and breed on oceanic islands, although it includes
some members of seabird families that breed inland.
Colonial. Several to hundreds of birds nesting in close
proximity.
Introduction
Seabirds are at home on land, in the air, and in water, making them unique among vertebrates. They often switch
between these three environments on a daily basis, which
requires unique physiology and morphological adaptations. They have adapted to all ecosystems on earth, from
the Arctic to Antarctica. Seabirds can be defined as those
that live, forage, and breed in marine environments,
including bays, estuaries, wetlands, coastal islands, oceanic islands, and the open ocean. They mainly forage at
sea, either nearshore or offshore, and can spend days,
weeks, and even years at sea without coming to land. Once
albatrosses leave their natal colony, they may wander the
oceans for 5–10 years before coming to land to breed.
While the ocean may seem uniform, seas vary with
seasonal cycles, El Nino events, and stochastically.
The distribution and foraging behavior of seabirds are
interconnected with oceanographic influences. For example, 50 species of seabirds are regular residents of the tropical Pacific Ocean, where specific currents, distinct water
masses, El Nino events, and the presence of marine mammals all affect seabird distribution (Balance et al., 2006).
Many seabirds forage with predatory fish or marine mammals because they force prey fish to the surface, making
them available to foraging seabirds.
Relevant life history
Seabirds are long-lived (20–60 years), delay breeding
(some albatrosses do not breed until they are 10 years
old), lay small clutch sizes (most lay only one egg), have
extended parental care (weeks to 6 months or more), and
range in size from a 0.24 kg Snow Petrel (Pagodroma
nivea) to a 16 kg male King Penguin (Aptenodytes
patagonicus). Thus, seabirds have low clutch sizes and
long-parental care, producing enough young to replace
538
SANDFLAT
Jorge Manuel López-Calderón
1
, Alf Meling
2 and
Rafael Riosmena-Rodríguez
1
1
Programa de Investigación en Botãnica Marina,
Departamento Académico de Biología Marina,
Universidad Autónoma de Baja California Sur, La Paz,
Baja California Sur, Mexico
2
Universidad Autónoma de Sonora, Hermosillo, Sonora,
Mexico
Synonyms
Mudflat; Tidal flat
Definition
A sandflat is an extension of unconsolidated sediment
located preferentially in the lower intertidal zone. It is an
unstable area characterized by the constant resuspension
of sediment by tidal flood and ebb currents. Tidal forces
predominate over other hydrodynamic processes, forming
well-sorted sand deposits.
Hydrodynamics
The amount of mud found in the sediment of a sandflat
is determined by the bed slope, the amount of fine sediments derived from land, and the strength of the current.
The sandflat-mudflat threshold is determined by the aforementioned factors. Finer muddy sediments accumulate
during neap tides, while coarser sandy sediments accumulate during spring tides. Hydrodynamic conditions of
sandflats preclude development of submerged aquatic
vegetation; however, there are important resident communities of burrowing invertebrates (worms, bivalves, crustaceans) that are fundamentally important for local trophic
networks and the recycling of nutrients. Sandflats can be
found adjacent to other types of habitats, such as
saltmarshes located in the upper intertidal zone (Perillo,
1996; Schwartz, 2005; Perillo et al., 2009).
Bibliography
Perillo, G. M. E. (ed.), 1996. Geomorphology and Sedimentology of
Estuaries. Amsterdam: Elsevier.
Perillo, G. M. E., Wolanski, E., Cahoon, D. R., and Brinson, M. M.
(eds.), 2009. Coastal Wetlands: An Integrated Ecosystem
Approach. Amsterdam: Elsevier.
Schwartz, M. L. (ed.), 2005. Encyclopedia of Coastal Science.
Dordrecht: Springer.
Cross-references
Sandbanks
Sediment Grain Size
Sediment Transport
Tidal Flat
Tidal Flat Salinity Gradient
SEABIRDS
Joanna Burger
Department of Cell Biology and Neurosciences, Ecology,
Evolution and Natural Resources, Department of Marine
and Coastal Sciences, Environmental and Occupational
Health Sciences Institute, Rutgers University, Piscataway,
NJ, USA
Synonyms
Estuarine birds; Marine birds; Pelagic birds
Definitions
Seabirds. Birds that live primarily on the oceans of the
world and breed on oceanic islands, although it includes
some members of seabird families that breed inland.
Colonial. Several to hundreds of birds nesting in close
proximity.
Introduction
Seabirds are at home on land, in the air, and in water, making them unique among vertebrates. They often switch
between these three environments on a daily basis, which
requires unique physiology and morphological adaptations. They have adapted to all ecosystems on earth, from
the Arctic to Antarctica. Seabirds can be defined as those
that live, forage, and breed in marine environments,
including bays, estuaries, wetlands, coastal islands, oceanic islands, and the open ocean. They mainly forage at
sea, either nearshore or offshore, and can spend days,
weeks, and even years at sea without coming to land. Once
albatrosses leave their natal colony, they may wander the
oceans for 5–10 years before coming to land to breed.
While the ocean may seem uniform, seas vary with
seasonal cycles, El Nino events, and stochastically.
The distribution and foraging behavior of seabirds are
interconnected with oceanographic influences. For example, 50 species of seabirds are regular residents of the tropical Pacific Ocean, where specific currents, distinct water
masses, El Nino events, and the presence of marine mammals all affect seabird distribution (Balance et al., 2006).
Many seabirds forage with predatory fish or marine mammals because they force prey fish to the surface, making
them available to foraging seabirds.
Relevant life history
Seabirds are long-lived (20–60 years), delay breeding
(some albatrosses do not breed until they are 10 years
old), lay small clutch sizes (most lay only one egg), have
extended parental care (weeks to 6 months or more), and
range in size from a 0.24 kg Snow Petrel (Pagodroma
nivea) to a 16 kg male King Penguin (Aptenodytes
patagonicus). Thus, seabirds have low clutch sizes and
long-parental care, producing enough young to replace
538
SANDFLAT