Pincebourde, S., Sanford, E., and Helmuth, B., 2008. Body temperature during low tide alters the feeding performance of a top
intertidal predator. Limnology and Oceanography, 53,
1562–1573.
Pörtner, H. O., 2010. Oxygen- and capacity-limitation of thermal
tolerance: a matrix for integrating climate-related stressor effects
in marine ecosystems. Journal of Experimental Biology, 213,
881–893.
Russell, B. D., Harley, C. D. G., Wernberg, T., Mieszkowska, N.,
Widdicombe, S., Hall-Spencer, J. M., and Connell, S. D., 2012.
Predicting ecosystem shifts requires new approaches that integrate the effects of climate change across entire systems. Biology
Letters, 8, 164–166.
Sanford, E., 2002. Water temperature, predation, and the neglected
role of physiological rate effects in rocky intertidal communities.
Integrative and Comparative Biology, 42, 881–891.
Somero, G. N., 2011. Comparative physiology: a “crystal ball” for
predicting consequences of global change. American Journal
of Physiology- Regulatory Integrative and Comparative Physiology, 301, R1–R14.
Southward, A. J., Langmead, O., Hardman-Mountford, N. J.,
Aitken, J., Boalch, G. T., Dando, P. R., Genner, M. J., Joint, I.,
Kendall, M. A., Halliday, N. C., Harris, R. P., Leaper, R.,
Mieszkowska, N., Pingree, R. D., Richardson, A. J., Sims,
D. W., Smith, T., Walne, A. W., Hawkins, S. J., et al., 2005.
Long-term oceanographic and ecological research in the western
English Channel. Advances in Marine Biology, 47, 1–105.
Wethey, D. S., 1984. Sun and shade mediate competition in the
barnacles Chthamalus and Semibalanus: a field experiment.
Biological Bulletin, 167, 176–185.
Cross-references
Climate Change
Ecological Niche
Environmental Gradients
Tides
TIDAL ASYMMETRY
Geórgenes H. Cavalcante
Institute of Atmospheric Science, Federal University of
Alagoas, Maceió, Alagoas, Brazil
Definition
Tidal asymmetry is defined by the discrepancies in the
duration of the falling and rising tides of water elevation.
This duration asymmetry may be manifested as an
inequality in flood/ebb tidal current magnitudes.
Description
Tidal asymmetry can produce two types of estuarine systems: flood dominant or ebb dominant. The system
referred to as flood dominant occurs when the duration
of the falling tide exceeds that of the rising tide leading
to a larger peak flood current (Headquarters, U.S. Army
Corps of Engineers, 2002); when the duration of the falling tide is shorter than that of the rising tide, it leads to
a stronger peak ebb current, and then the system is referred
to as ebb dominant.
The sources behind the asymmetrical tides are the interactions of multiple tidal constituents (Boon and Byrne,
1981). Phase difference between constituents dictates the
direction of asymmetry (i.e., flood or ebb dominance),
while the ratio of constituent amplitudes reflects the
degree of distortion (Friedrichs and Aubrey, 1988).
Bibliography
Boon, J. D., and Byrne, R. J., 1981. On basin hypsometry and the
morphodynamic response of coastal inlet systems. Marine Geology, 40(1–2), 27–48.
Friedrichs, C. T., and Aubrey, D. G., 1988. Non-linear tidal distortion in shallow well-mixed estuaries: a synthesis. Estuarine
Coastal Shelf Science, 27(5), 521–545.
Headquarters, U.S. Army Corps of Engineers, 2002. Tidal Velocity
Asymmetry at Inlets. Washington, DC: ERDC/CHL CHETNIV-47.
Cross-references
Tidal Hydrodynamics
Tidal Ranges
TIDAL DATUM
Ivan D. Haigh
Ocean and Earth Science, National Oceanography Centre,
University of Southampton, European Way,
Southampton, UK
Definition
A tidal datum is a reference elevation of sea level, defined
in terms of a certain phase of a tide. Tidal datums are
primarily used to estimate water heights and/or depths
and determine horizontal boundaries. Tidal datums are
fundamental to the determination of spatial coordinates
of latitude, longitude, and elevation relative to mean sea
level. They are also essential as legal entities to establish
the limits of state jurisdiction over maritime zones
(NOAA, 2000).
Description
Tidal datums are local because they are estimated from
water level observations made at a particular tide gauge
site. Tidal ranges vary considerably spatially depending
on local hydrodynamic and topographic characteristics
(e.g., tidal range may be much larger at the head of an estuary compared to the mouth), and hence tidal datums vary
accordingly. Therefore they should not be extended into
areas with significantly different oceanographic characteristics without sufficient observations (or numerical modeling) to support any such extrapolation.
Tidal datums are usually estimated statistically from
water level observations made over a tidal datum epoch,
which is the interval of time recommended to calculate
tidal datums. This interval is usually at least 19 years, to
664
TIDAL ASYMMETRY
intertidal predator. Limnology and Oceanography, 53,
1562–1573.
Pörtner, H. O., 2010. Oxygen- and capacity-limitation of thermal
tolerance: a matrix for integrating climate-related stressor effects
in marine ecosystems. Journal of Experimental Biology, 213,
881–893.
Russell, B. D., Harley, C. D. G., Wernberg, T., Mieszkowska, N.,
Widdicombe, S., Hall-Spencer, J. M., and Connell, S. D., 2012.
Predicting ecosystem shifts requires new approaches that integrate the effects of climate change across entire systems. Biology
Letters, 8, 164–166.
Sanford, E., 2002. Water temperature, predation, and the neglected
role of physiological rate effects in rocky intertidal communities.
Integrative and Comparative Biology, 42, 881–891.
Somero, G. N., 2011. Comparative physiology: a “crystal ball” for
predicting consequences of global change. American Journal
of Physiology- Regulatory Integrative and Comparative Physiology, 301, R1–R14.
Southward, A. J., Langmead, O., Hardman-Mountford, N. J.,
Aitken, J., Boalch, G. T., Dando, P. R., Genner, M. J., Joint, I.,
Kendall, M. A., Halliday, N. C., Harris, R. P., Leaper, R.,
Mieszkowska, N., Pingree, R. D., Richardson, A. J., Sims,
D. W., Smith, T., Walne, A. W., Hawkins, S. J., et al., 2005.
Long-term oceanographic and ecological research in the western
English Channel. Advances in Marine Biology, 47, 1–105.
Wethey, D. S., 1984. Sun and shade mediate competition in the
barnacles Chthamalus and Semibalanus: a field experiment.
Biological Bulletin, 167, 176–185.
Cross-references
Climate Change
Ecological Niche
Environmental Gradients
Tides
TIDAL ASYMMETRY
Geórgenes H. Cavalcante
Institute of Atmospheric Science, Federal University of
Alagoas, Maceió, Alagoas, Brazil
Definition
Tidal asymmetry is defined by the discrepancies in the
duration of the falling and rising tides of water elevation.
This duration asymmetry may be manifested as an
inequality in flood/ebb tidal current magnitudes.
Description
Tidal asymmetry can produce two types of estuarine systems: flood dominant or ebb dominant. The system
referred to as flood dominant occurs when the duration
of the falling tide exceeds that of the rising tide leading
to a larger peak flood current (Headquarters, U.S. Army
Corps of Engineers, 2002); when the duration of the falling tide is shorter than that of the rising tide, it leads to
a stronger peak ebb current, and then the system is referred
to as ebb dominant.
The sources behind the asymmetrical tides are the interactions of multiple tidal constituents (Boon and Byrne,
1981). Phase difference between constituents dictates the
direction of asymmetry (i.e., flood or ebb dominance),
while the ratio of constituent amplitudes reflects the
degree of distortion (Friedrichs and Aubrey, 1988).
Bibliography
Boon, J. D., and Byrne, R. J., 1981. On basin hypsometry and the
morphodynamic response of coastal inlet systems. Marine Geology, 40(1–2), 27–48.
Friedrichs, C. T., and Aubrey, D. G., 1988. Non-linear tidal distortion in shallow well-mixed estuaries: a synthesis. Estuarine
Coastal Shelf Science, 27(5), 521–545.
Headquarters, U.S. Army Corps of Engineers, 2002. Tidal Velocity
Asymmetry at Inlets. Washington, DC: ERDC/CHL CHETNIV-47.
Cross-references
Tidal Hydrodynamics
Tidal Ranges
TIDAL DATUM
Ivan D. Haigh
Ocean and Earth Science, National Oceanography Centre,
University of Southampton, European Way,
Southampton, UK
Definition
A tidal datum is a reference elevation of sea level, defined
in terms of a certain phase of a tide. Tidal datums are
primarily used to estimate water heights and/or depths
and determine horizontal boundaries. Tidal datums are
fundamental to the determination of spatial coordinates
of latitude, longitude, and elevation relative to mean sea
level. They are also essential as legal entities to establish
the limits of state jurisdiction over maritime zones
(NOAA, 2000).
Description
Tidal datums are local because they are estimated from
water level observations made at a particular tide gauge
site. Tidal ranges vary considerably spatially depending
on local hydrodynamic and topographic characteristics
(e.g., tidal range may be much larger at the head of an estuary compared to the mouth), and hence tidal datums vary
accordingly. Therefore they should not be extended into
areas with significantly different oceanographic characteristics without sufficient observations (or numerical modeling) to support any such extrapolation.
Tidal datums are usually estimated statistically from
water level observations made over a tidal datum epoch,
which is the interval of time recommended to calculate
tidal datums. This interval is usually at least 19 years, to
664
TIDAL ASYMMETRY