Intertidal ecology

Intertidal ecology is the study of intertidal ecosystems, where organisms live between the low and high tide lines. At low tide, the intertidal is exposed whereas at high tide, the intertidal is underwater. Intertidal ecologists therefore study the interactions between intertidal organisms and their environment, as well as between different species of intertidal organisms within a particular intertidal community. The most important environmental and species interactions may vary based on the type of intertidal community being studied, the broadest of classifications being based on substrates—rocky shore and soft bottom communities.[1][2]

Organisms living in this zone have a highly variable and often hostile environment, and have evolved various adaptations to cope with and even exploit these conditions. One easily visible feature of intertidal communities is vertical zonation, where the community is divided into distinct vertical bands of specific species going up the shore. Species ability to cope with abiotic factors associated with emersion stress, such as desiccation determines their upper limits, while biotic interactions e.g.competition with other species sets their lower limits.[1]

Intertidal regions are utilized by humans for food and recreation, but anthropogenic actions also have major impacts, with overexploitation, invasive species and climate change being among the problems faced by intertidal communities. In some places Marine Protected Areas have been established to protect these areas and aid in scientific research.[3]

Anjajavy forest meets sea
Anjajavy Forest on Tsingy rocks jutting into the Indian Ocean.

Types of intertidal communities

Intertidal habitats can be characterized as having either hard or soft bottoms substrates.[4] Rocky intertidal communities occur on rocky shores, such as headlands, cobble beaches, or human-made jetties. Their degree of exposure may be calculated using the Ballantine Scale.[5][6] Soft-sediment habitats include sandy beaches, and intertidal wetlands (e.g., mudflats and salt marshes). These habitats differ in levels of abiotic, or non-living, environmental factors. Rocky shores tend to have higher wave action, requiring adaptations allowing the inhabitants to cling tightly to the rocks. Soft-bottom habitats are generally protected from large waves but tend to have more variable salinity levels. They also offer a third habitable dimension: depth. Thus, many soft-sediment inhabitants are adapted for burrowing.[7][8]


Intertide zonation at Kalaloch
A rock, seen at low tide, exhibiting typical intertidal zonation.

Because intertidal organisms endure regular periods of immersion and emersion, they essentially live both underwater and on land and must be adapted to a large range of climatic conditions. The intensity of climate stressors varies with relative tide height because organisms living in areas with higher tide heights are emersed for longer periods than those living in areas with lower tide heights. This gradient of climate with tide height leads to patterns of intertidal zonation, with high intertidal species being more adapted to emersion stresses than low intertidal species. These adaptations may be behavioral (i.e. movements or actions), morphological (i.e. characteristics of external body structure), or physiological (i.e. internal functions of cells and organs).[9] In addition, such adaptations generally cost the organism in terms of energy (e.g. to move or to grow certain structures), leading to trade-offs (i.e. spending more energy on deterring predators leaves less energy for other functions like reproduction).

Intertidal organisms, especially those in the high intertidal, must cope with a large range of temperatures. While they are underwater, temperatures may only vary by a few degrees over the year. However, at low tide, temperatures may dip to below freezing or may become scaldingly hot, leading to a temperature range that may approach 30 °C (86 °F) during a period of a few hours. Many mobile organisms, such as snails and crabs, avoid temperature fluctuations by crawling around and searching for food at high tide and hiding in cool, moist refuges (crevices or burrows) at low tide.[10] Besides simply living at lower tide heights, non-motile organisms may be more dependent on coping mechanisms. For example, high intertidal organisms have a stronger stress response, a physiological response of making proteins that help recovery from temperature stress just as the immune response aids in the recovery from infection.[11]

Intertidal organisms are also especially prone to desiccation during periods of emersion. Again, mobile organisms avoid desiccation in the same way as they avoid extreme temperatures: by hunkering down in mild and moist refuges. Many intertidal organisms, including Littorina snails, prevent water loss by having waterproof outer surfaces, pulling completely into their shells, and sealing shut their shell opening. Limpets (Patella) do not use such a sealing plate but occupy a home-scar to which they seal the lower edge of their flattened conical shell using a grinding action. They return to this home-scar after each grazing excursion, typically just before emersion. On soft rocks, these scars are quite obvious. Still other organisms, such as the algae Ulva and Porphyra, are able to rehydrate and recover after periods of severe desiccation.

The level of salinity can also be quite variable. Low salinities can be caused by rainwater or river inputs of freshwater. Estuarine species must be especially euryhaline, or able to tolerate a wide range of salinities. High salinities occur in locations with high evaporation rates, such as in salt marshes and high intertidal pools. Shading by plants, especially in the salt marsh, can slow evaporation and thus ameliorate salinity stress. In addition, salt marsh plants tolerate high salinities by several physiological mechanisms, including excreting salt through salt glands and preventing salt uptake into the roots.

In addition to these exposure stresses (temperature, desiccation, and salinity), intertidal organisms experience strong mechanical stresses, especially in locations of high wave action. There are myriad ways in which the organisms prevent dislodgement due to waves.[12] Morphologically, many mollusks (such as limpets and chitons) have low-profile, hydrodynamic shells. Types of substrate attachments include mussels' tethering byssal threads and glues, sea stars' thousands of suctioning tube feet, and isopods' hook-like appendages that help them hold on to intertidal kelps. Higher profile organisms, such as kelps, must also avoid breaking in high flow locations, and they do so with their strength and flexibility. Finally, organisms can also avoid high flow environments, such as by seeking out low flow microhabitats. Additional forms of mechanical stresses include ice and sand scour, as well as dislodgment by water-borne rocks, logs, etc.

For each of these climate stresses, species exist that are adapted to and thrive in the most stressful of locations. For example, the tiny crustacean copepod Tigriopus thrives in very salty, high intertidal tidepools, and many filter feeders find more to eat in wavier and higher flow locations. Adapting to such challenging environments gives these species competitive edges in such locations.

Food web structure

During tidal immersion, the food supply to intertidal organisms is subsidized by materials carried in seawater, including photosynthesizing phytoplankton and consumer zooplankton. These plankton are eaten by numerous forms of filter feedersmussels, clams, barnacles, sea squirts, and polychaete worms—which filter seawater in their search for planktonic food sources.[13] The adjacent ocean is also a primary source of nutrients for autotrophs, photosynthesizing producers ranging in size from microscopic algae (e.g. benthic diatoms) to huge kelps and other seaweeds. These intertidal producers are eaten by herbivorous grazers, such as limpets that scrape rocks clean of their diatom layer and kelp crabs that creep along blades of the feather boa kelp Egregia eating the tiny leaf-shaped bladelets. Crabs are eaten by goliath grouper, which are then eaten by sharks. Higher up the food web, predatory consumers—especially voracious starfish—eat other grazers (e.g. snails) and filter feeders (e.g. mussels).[14] Finally, scavengers, including crabs and sand fleas, eat dead organic material, including dead producers and consumers.

Species interactions

Tide pools in santa cruz
Tide pools with sea stars and sea anemone in Santa Cruz, California

In addition to being shaped by aspects of climate, intertidal habitats—especially intertidal zonation patterns—are strongly influenced by species interactions, such as predation, competition, facilitation, and indirect interactions. Ultimately, these interactions feed into the food web structure, described above. Intertidal habitats have been a model system for many classic ecological studies, including those introduced below, because the resident communities are particularly amenable to experimentation.

One dogma of intertidal ecology—supported by such classic studies—is that species' lower tide height limits are set by species interactions whereas their upper limits are set by climate variables. Classic studies by Robert Paine[13][15] established that when sea star predators are removed, mussel beds extend to lower tide heights, smothering resident seaweeds. Thus, mussels' lower limits are set by sea star predation. Conversely, in the presence of sea stars, mussels' lower limits occur at a tide height at which sea stars are unable to tolerate climate conditions.

Competition, especially for space, is another dominant interaction structuring intertidal communities. Space competition is especially fierce in rocky intertidal habitats, where habitable space is limited compared to soft-sediment habitats in which three-dimensional space is available. As seen with the previous sea star example, mussels are competitively dominant when they are not kept in check by sea star predation. Joseph Connell's research on two types of high intertidal barnacles, Balanus balanoides, now Semibalanus balanoides, and a Chthamalus stellatus, showed that zonation patterns could also be set by competition between closely related organisms.[16] In this example, Balanus outcompetes Chthamalus at lower tide heights but is unable to survive at higher tide heights. Thus, Balanus conforms to the intertidal ecology dogma introduced above: its lower tide height limit is set by a predatory snail and its higher tide height limit is set by climate. Similarly, Chthamalus, which occurs in a refuge from competition (similar to the temperature refuges discussed above), has a lower tide height limit set by competition with Balanus and a higher tide height limit is set by climate.

Hermit crabs scavenge at Gumboot chiton 2
Hermit crabs and live Tegula snails on a dead gumboot chiton, Cryptochiton stelleri, in a tide pool at low tide in central California

Although intertidal ecology has traditionally focused on these negative interactions (predation and competition), there is emerging evidence that positive interactions are also important.[17] Facilitation refers to one organism helping another without harming itself. For example, salt marsh plant species of Juncus and Iva are unable to tolerate the high soil salinities when evaporation rates are high, thus they depend on neighboring plants to shade the sediment, slow evaporation, and help maintain tolerable salinity levels.[18] In similar examples, many intertidal organisms provide physical structures that are used as refuges by other organisms. Mussels, although they are tough competitors with certain species, are also good facilitators as mussel beds provide a three-dimensional habitat to species of snails, worms, and crustaceans.

All of the examples given so far are of direct interactions: Species A eat Species B or Species B eats Species C. Also important are indirect interactions[19] where, using the previous example, Species A eats so much of Species B that predation on Species C decreases and Species C increases in number. Thus, Species A indirectly benefits Species C. Pathways of indirect interactions can include all other forms of species interactions. To follow the sea star-mussel relationship, sea stars have an indirect negative effect on the diverse community that lives in the mussel bed because, by preying on mussels and decreasing mussel bed structure, those species that are facilitated by mussels are left homeless. Additional important species interactions include mutualism, which is seen in symbioses between sea anemones and their internal symbiotic algae, and parasitism, which is prevalent but is only beginning to be appreciated for its effects on community structure.

Current topics

Humans are highly dependent on intertidal habitats for food and raw materials,[20] and over 50% of humans live within 100 km of the coast. Therefore, intertidal habitats are greatly influenced by human impacts to both ocean and land habitats. Some of the conservation issues associated with intertidal habitats and at the head of the agendas of managers and intertidal ecologists are:

1. Climate change: Intertidal species are challenged by several of the effects of global climate change, including increased temperatures, sea level rise, and increased storminess. Ultimately, it has been predicted that the distributions and numbers of species will shift depending on their abilities to adapt (quickly!) to these new environmental conditions.[20] Due to the global scale of this issue, scientists are mainly working to understand and predict possible changes to intertidal habitats.

2. Invasive species: Invasive species are especially prevalent in intertidal areas with high volumes of shipping traffic, such as large estuaries, because of the transport of non-native species in ballast water.[21] San Francisco Bay, in which an invasive Spartina cordgrass from the east coast is currently transforming mudflat communities into Spartina meadows, is among the most invaded estuaries in the world. Conservation efforts are focused on trying to eradicate some species (like Spartina) in their non-native habitats as well as preventing further species introductions (e.g. by controlling methods of ballast water uptake and release).

3. Marine protected areas: Many intertidal areas are lightly to heavily exploited by humans for food gathering (e.g. clam digging in soft-sediment habitats and snail, mussel, and algal collecting in rocky intertidal habitats). In some locations, marine protected areas have been established where no collecting is permitted. The benefits of protected areas may spill over to positively impact adjacent unprotected areas. For example, a greater number of larger egg capsules of the edible snail Concholepus in protected vs. non-protected areas in Chile indicates that these protected areas may help replenish snail stocks in areas open to harvesting.[22] The degree to which collecting is regulated by law differs with the species and habitat.

See also


  1. ^ a b Raffaelli, David; Hawkins, Stephen J. (1996). Intertidal Ecology. Springer. ISBN 978-0-412-29950-6.
  2. ^ Tomanek, Lars; Helmuth, Brian (August 2002). "Physiological Ecology of Rocky Intertidal Organisms: A Synergy of Concepts" (PDF). Integrative and Comparative Biology. 42 (4): 771–775. doi:10.1093/icb/42.4.771.
  3. ^ National Academy of Sciences. Marine protected areas: tools for sustaining ocean ecosystems/ Committee on the evaluation, design, and monitoring of marine reserves and protected areas in the United States Ocean Studies Board Commission on Geosciences, Environment, and Resources National Research Council. National Academy Press, Washington, D.C., 2001
  4. ^ Dugan, Jenifer E.; Hubbard, David M.; Quigley, Brenna J. (October 2013). "Beyond beach width: Steps toward identifying and integrating ecological envelopes with geomorphic features and datums for sandy beach ecosystems". Geomorphology. 199: 95–105. doi:10.1016/j.geomorph.2013.04.043.
  5. ^ Ballantine, W.J. (1961). "A Biologically-defined Exposure Scale for the Comparative Description of Rocky Shores". Field Studies Journal. 1 (3).
  6. ^ Dethier, Megan N. (April 1992). "Classifying marine and estuarine natural communities: an alternative to the Cowardin system". Natural Areas Journal. 12 (2): 90–100. JSTOR 43911274.
  7. ^ Banks, Simon A.; Skilleter, Greg A. (2002). "Mapping intertidal habitats and an evaluation of their conservation status in Queensland, Australia". Ocean & Coastal Management. 45 (8): 485–509. doi:10.1016/S0964-5691(02)00082-0.
  8. ^ Kelleher, Graeme; Bleakley, Chris; Wells, Sue C. A Global Representative System of Marine Protected Areas: Antarctic, Artic, Mediterranean, Northwest Atlantic and Baltic (partial document). Vol. I. Washington, D.C.: The International Bank for Reconstruction/The World Bank, 1995.
  9. ^ Somero, George N. (2002). "Thermal Physiology and Vertical Zonation of Intertidal Animals: Optima, Limits, and Costs of Living". Integrative and Comparative Biology. 42 (4): 780–789. doi:10.1093/icb/42.4.780.
  10. ^ Burnaford, Jennifer L. (October 2004). "Habitat modification and refuge from sublethal stress drive a marine plant-herbivore association". Ecology. 85 (10): 2837–2849. doi:10.1890/03-0113. JSTOR 3450442.
  11. ^ Ricketts, Edward F.; Calvin, Jack; Hedgpeth, Joel W. (1992). Between Pacific Tides (Fifth ed.). Stanford University Press.
  12. ^ Leigh, Egbert G., Jr.; Paine, Robert T.; Quinn, James F.; Suchanek, Thomas H. (March 1987). "Wave energy and intertidal productivity" (PDF). Proceedings of the National Academy of Sciences of the United States of America. 84 (5): 1314–1318. doi:10.1073/pnas.84.5.1314. OSTI 6128805. PMC 304418.
  13. ^ a b Paine, Robert T. (January–February 1966). "Food Web Complexity and Species Diversity" (PDF). The American Naturalist. 100 (910): 65–75. doi:10.1086/282400. JSTOR 2459379.
  14. ^ Trussell, Geoffrey C.; Ewanchuk, Patrick J.; Bertness, Mark D. (March 2002). "Field evidence of trait-mediated indirect interactions in a rocky intertidal food web" (PDF). Ecology Letters. 5 (2): 241–245. doi:10.1046/j.1461-0248.2002.00304.x.
  15. ^ Paine, R.T. (June 1974). "Intertidal Community Structure: Experimental Studies on the Relationship between a Dominant Competitor and Its Principal Predator". Oecologia. 15 (2): 93–120. doi:10.1007/BF00345739. JSTOR 4214949.
  16. ^ Connell, Joseph H. (October 1961). "The Influence of Interspecific Competition and Other Factors on the Distribution of the Barnacle Chthamalus stellatus" (PDF). Ecology. 42 (4): 710–723. doi:10.2307/1933500. JSTOR 1933500.
  17. ^ Bruno, John F.; Stachowicz, John J.; Berntess, Mark D. (March 2003). "Inclusion of facilitation into ecological theory" (PDF). Trends in Ecology & Evolution. 18 (3): 119–125. doi:10.1016/S0169-5347(02)00045-9.
  18. ^ Bertness, Mark D.; Hacker, Sally D. (September 1994). "Physical Stress and Positive Associations Among Marsh Plants". The American Naturalist. 144 (3): 363–372. doi:10.1086/285681.
  19. ^ Menge, Bruce A. (February 1995). "Indirect Effects in Marine Rocky Intertidal Interaction Webs: Patterns and Importance". Ecological Monographs. 65 (1): 21–74. doi:10.2307/2937158. JSTOR 2937158.
  20. ^ a b Harley, Christopher D.G.; et al. (January 2006). "The impacts of climate change in coastal marine systems". Ecology Letters. 9 (2): 228–241. doi:10.1111/j.1461-0248.2005.00871.x.
  21. ^ Cohen, Andrew N.; Carlton, James T. (January 23, 1998). "Accelerating Invasion Rate in a Highly Invaded Estuary" (PDF). Science. 279 (5350): 555–558. doi:10.1126/science.279.5350.555.
  22. ^ Manríquez, Patricio H.; Castilla, Juan Carlos (2001). "Significance of marine protected areas in central Chile as seeding grounds for the gastropod Concholepas concholepas" (PDF). Marine Ecology Progress Series. 215: 201–211. doi:10.3354/meps215201.


  • Bertness, M. D., S. D. Gaines, and M. E. Hay (2001) Marine community ecology. Sinauer Associates, Inc.
  • Kozloff E. N. (1973) Seashore life of the northern Pacific coast. University of Washington Press.
  • Ricketts E. F., J. Calvin and J. W. Hedgpeth (1939) Between Pacific Tides (5th Ed.) Stanford University Press.

External links

Aquatic ecosystem

An aquatic ecosystem is an ecosystem in a body of water. Communities of organisms that are dependent on each other and on their environment live in aquatic ecosystems. The two main types of aquatic ecosystems are marine ecosystems and freshwater ecosystems.


Benthos is the community of organisms that live on, in, or near the seabed, river, lake, or stream bottom, also known as the benthic zone. This community lives in or near marine or freshwater sedimentary environments, from tidal pools along the foreshore, out to the continental shelf, and then down to the abyssal depths.

Many organisms adapted to deep-water pressure cannot survive in the upperparts of the water column. The pressure difference can be very significant (approximately one atmosphere for each 10 metres of water depth).Because light is absorbed before it can reach deep ocean-water, the energy source for deep benthic ecosystems is often organic matter from higher up in the water column that drifts down to the depths. This dead and decaying matter sustains the benthic food chain; most organisms in the benthic zone are scavengers or detritivores.

The term benthos, coined by Haeckel in 1891, comes from the Greek noun βένθος "depth of the sea". Benthos is used in freshwater biology to refer to organisms at the bottom of freshwater bodies of water, such as lakes, rivers, and streams. There is also a redundant synonym, benthon.

Between Pacific Tides

Between Pacific Tides is a 1939 book by Ed Ricketts and Jack Calvin that explores the intertidal ecology of the Pacific coast of the United States. The book was originally titled "Between Pacific Tides: An Account of the Habits and Habitats of Some Five Hundred of the Common, Conspicuous Seashore Invertebrates of the Pacific Coast Between Sitka, Alaska, and Northern Mexico".

Prior to Ricketts' work, the standard descriptive text of intertidal species of the Pacific was Myrtle E. Johnson's Seashore Animals of the Pacific Coast, published in 1927 (repr. 1967).

Between Pacific Tides was out of print from 1942 to 1948, but it has since been revised and updated to keep it current, and is now in its fifth edition with the size increasing around twenty percent from the original. Updated and expanded sections have been added since the original edition was published, including: John Steinbeck's Foreword to the 1948 edition; a new chapter regarding the influence on the distribution of shore organisms; an updated Annotated Systematic Index and General Bibliography comprising 2,300 entries; and the addition of 200 photographs and drawings.By 2004, the book had sold around 100,000 copies, making it one of the best-selling books published by Stanford University Press.

Ed Ricketts

Edward Flanders Robb Ricketts (May 14, 1897 – May 11, 1948) commonly known as Ed Ricketts, was an American marine biologist, ecologist, and philosopher. He is best known for Between Pacific Tides (1939), a pioneering study of intertidal ecology, and for his influence on writer John Steinbeck, which resulted in their collaboration on the Sea of Cortez, later republished as The Log from the Sea of Cortez (1951).

Floodplain restoration

Floodplain restoration is the process of fully or partially restoring a river's floodplain to its original conditions before having been affected by the construction of levees (dikes) and the draining of wetlands and marshes.

The objectives of restoring floodplains include the reduction of the incidence of floods, the provision of habitats for aquatic species, the improvement of water quality and the increased recharge of groundwater.

Index of fishing articles

This page is a list of fishing topics.


Limnology ( lim-NOL-ə-jee; from Greek λίμνη, limne, "lake" and λόγος, logos, "knowledge"), is the study of inland aquatic ecosystems.

The study of limnology includes aspects of the biological, chemical, physical, and geological characteristics and functions of inland waters (running and standing waters, fresh and saline, natural or man-made). This includes the study of lakes, reservoirs, ponds, rivers, springs, streams, wetlands, and groundwater. A more recent sub-discipline of limnology, termed landscape limnology, studies, manages, and seeks to conserve these ecosystems using a landscape perspective, by explicitly examining connections between an aquatic ecosystem and its watershed. Recently, the need to understand global inland waters as part of the Earth System created a sub-discipline called global limnology. This approach considers processes in inland waters on a global scale, like the role of inland aquatic ecosystems in global biogeochemical cycles.Limnology is closely related to aquatic ecology and hydrobiology, which study aquatic organisms and their interactions with the abiotic (non-living) environment. While limnology has substantial overlap with freshwater-focused disciplines (e.g., freshwater biology), it also includes the study of inland salt lakes.

List of marine biologists

This is a list of marine biologists.

Donald Putnam Abbott (1920–1986), American marine invertebrate zoologist

Isabella Aiona Abbott (1919–2010), American marine botanist

Ali Abdelghany (born 1944), Egyptian marine biologist

Jakob Johan Adolf Appellöf (1857–1921), Swedish marine zoologist

Leanne Armand (born 1968), Australian marine scientist

Samuel Stillman Berry (1887–1984), American marine zoologist

Henry Bryant Bigelow (1879–1967), American marine biologist

Jean Bouillon (1926–2009), Belgian marine zoologist

Rachel Carson (1907–1964), American marine biologist and author

Carl Chun (1852–1914), German marine biologist

Eugenie Clark (1922–2015), American marine biologist

Malcolm Clarke (1930–2013), British cephalopod expert

Jacques-Yves Cousteau (1910–1997), French marine explorer, conservationist, and filmmaker

Charles Darwin (1809–1882), wrote Structure and Distribution of Coral Reefs (1842) while aboard HMS Beagle

Paul K. Dayton (born 1941), American benthic marine ecologist noted for work in kelp forest ecology

Anton Dohrn (1840–1909), German marine biologist

Nicole Dubilier, American marine microbiologist, head of Max Planck Institute for Marine Microbiology

Patricia Louise Dudley (1929–2004) American zoologist specializing in copepods

Sylvia Earle (born 1935), American oceanographer

Ruth Gates (1962–2018), American marine biologist noted for work on coral reefs

J. Frederick Grassle (1939-2018), American marine biologist

Gordon Gunter (1909–1998), American marine biologist and fisheries scientist notable for pioneering fisheries research in the northern Gulf of Mexico

Ernst Haeckel (1834–1919), German physician, zoologist, marine biologist and evolutionist

Benjamin Halpern, American marine conservationist

Hans Hass (born 1919), Austrian marine biologist and diving pioneer

Gotthilf Hempel (born 1929), German marine biologist

Stephen Hillenburg (1961–2018), American animator (creator of SpongeBob SquarePants); previously worked as a marine biology teacher for several years

Hirohito, the Shōwa Emperor (1901–1989), jellyfish taxonomist

Johan Hjort (1869–1948), Norwegian marine zoologist and one of the founders of ICES

Bruno Hofer (1861–1916), German fisheries scientist

Martin W. Johnson (1893–1984), American marine biologist and biological oceanographer

Uwe Kils (born 1951), German marine biologist

Otto Kinne (born 1923), German marine biologist

Nancy Knowlton, coral reef biologist and author of Citizens of the Sea (2010)

August David Krohn (1803–1891), Russian/German zoologist

Paul L. Kramp (1887–1975), Danish zoologist working on jellyfish

William Elford Leach (1790–1836), English zoologist and marine biologist

Nicholai Miklukho-Maklai (1846–1888), Russian marine biologist and anthropologist

Sir John Murray (1841–1914), Scots-Canadian marine biologist

Anders Sandøe Ørsted (1816–1872), Danish marine botanist studied arctic nematodes and marine algae

Robert T. Paine (1933–2016), American marine zoologist known for developing the "keystone species" concept

Joseph R. Pawlik (born 1960), American marine biologist

Ronald C. Phillips (1932–2005), American marine botanist, co-author of Seagrasses (1980); worldwide development of seagrass science told in autobiographical Travels with Seagrass (2013)

Syed Zahoor Qasim (born 1926), Indian marine biologist

Ed Ricketts (1897–1948), American marine biologist noted for a pioneering study of intertidal ecology

Harald Rosenthal (born 1937), German hydrobiologist known for his work in fish farming and ecology

Anne Rudloe (1947–2012), American co-founder of Gulf Specimen Marine Laboratory

Jack Rudloe (born 1943), American co-founder of Gulf Specimen Marine Laboratory and writer of several popular works on the sea including The Sea Brings Forth, and The Erotic Ocean.

Frederick Stratten Russell (1897-1984), British marine biologist known for his work on zooplankton.

Georg Sars (1837–1927), Norwegian marine biologist

Michael Sars (1809–1869), Norwegian theologian and biologist

Oscar Elton Sette (1900–1972), American fisheries scientist notable for pioneering modern fisheries science and fisheries oceanography

Bell M. Shimada (1922–1958), American fisheries scientist notable for pioneering studies of tuna stocks in the equatorial Pacific Ocean

Ronald Shimek (born 1948), American marine biologist noted mainly for his work on scaphopods and turrid gastropods

Charles Wyville Thompson (1832–1882), Scottish marine biologist

Gunnar Thorson (1906–1971), Danish marine biologist

Anne Thynne (1800–1866), British marine zoologist

Takasi Tokioka (1913–2001), Japanese marine biologist known for his work on soft bodied zooplankton and tunicates

Ruth Turner (1915–2000), marine biologist

Anna Weber-van Bosse (1852–1942), marine phycologist

List of watershed topics

This list embraces topographical watersheds and drainage basins and other topics focused on them.

Littoral zone

The littoral zone or nearshore is the part of a sea, lake, or river that is close to the shore. In coastal environments, the littoral zone extends from the high water mark, which is rarely inundated, to shoreline areas that are permanently submerged. The littoral zone always includes this intertidal zone, and the terms are often used interchangeably. However, the meaning of littoral zone can extend well beyond the intertidal zone.

The term has no single definition. What is regarded as the full extent of the littoral zone, and the way the littoral zone is divided into subregions, varies in different contexts. (Lakes and rivers have their own definitions.) The use of the term also varies from one part of the world to another, and between different disciplines. For example, military commanders speak of the littoral in ways that are quite different from marine biologists.

The adjacency of water gives a number of distinctive characteristics to littoral regions. The erosive power of water results in particular types of landforms, such as sand dunes, and estuaries. The natural movement of the littoral along the coast is called the littoral drift. Biologically, the ready availability of water enables a greater variety of plant and animal life, and particularly the formation of extensive wetlands. In addition, the additional local humidity due to evaporation usually creates a microclimate supporting unique types of organisms.

The word littoral may be used both as a noun and as an adjective. It derives from the Latin noun litus, litoris, meaning "shore". (The doubled tt is a late-medieval innovation, and the word is sometimes seen in the more classical-looking spelling litoral.)

Omana Regional Park

Omana Regional Park is situated 42 km (40 mins) drive south east of Auckland city, New Zealand just before entering Maraetai township. Open 8am-5pm (winter) or 8.30pm (summer).

Particle (ecology)

In marine and freshwater ecology, a particle is a small object. Particles can remain in suspension in the ocean or freshwater. However, they eventually settle (rate determined by Stokes' law) and accumulate as sediment. Some can enter the atmosphere through wave action where they can act as cloud condensation nuclei (CCN). Many organisms filter particles out of the water with unique filtration mechanisms (filter feeders). Particles are often associated with high loads of toxins which attach to the surface. As these toxins are passed up the food chain they accumulate in fatty tissue and become increasingly concentrated in predators (see bioaccumulation). Very little is known about the dynamics of particles, especially when they are re-suspended by dredging. They can remain floating in the water and drift over long distances. The decomposition of some particles by bacteria consumes a lot of oxygen and can cause the water to become hypoxic.

Photic zone

The photic zone, euphotic zone (Greek for "well lit": εὖ "well" + φῶς "light"), or sunlight (or sunlit) zone is the uppermost layer of water in a lake or ocean that is exposed to intense sunlight. It corresponds roughly to the layer above the compensation point, i.e. depth where the rate of carbon dioxide uptake, or equivalently, the rate of photosynthetic oxygen production, is equal to the rate of carbon dioxide production, equivalent to the rate of respiratory oxygen consumption, i.e. the depth where net carbon dioxide assimilation is zero.

It extends from the surface down to a depth where light intensity falls to one percent of that at the surface, called the euphotic depth. Accordingly, its thickness depends on the extent of light attenuation in the water column. Typical euphotic depths vary from only a few centimetres in highly turbid eutrophic lakes, to around 200 meters in the open ocean. It also varies with seasonal changes in turbidity.

Since the photic zone is where almost all of the photosynthesis occurs, the depth of the photic zone is generally proportional to the level of primary production that occurs in that area of the ocean. About 90% of all marine life lives in the photic zone. A small amount of primary production is generated deep in the abyssal zone around the hydrothermal vents which exist along some mid-oceanic ridges.

The zone which extends from the base of the euphotic zone to about 200 metres is sometimes called the disphotic zone. While there is some light, it is insufficient for photosynthesis, or at least insufficient for photosynthesis at a rate greater than respiration. The euphotic zone together with the disphotic zone coincides with the epipelagic zone. The bottommost zone, below the euphotic zone, is called the aphotic zone. Most deep ocean waters belong to this zone.

The transparency of the water, which determines the depth of the photic zone, is measured simply with a Secchi disk. It may also be measured with a photometer lowered into the water.

Ramsar site

A Ramsar site is a wetland site designated to be of international importance under the Ramsar Convention.The Convention on Wetlands, known as the Ramsar Convention, is an intergovernmental environmental treaty established in 1971 by UNESCO, which came into force in 1975. It provides for national action and international cooperation regarding the conservation of wetlands, and wise sustainable use of their resources.Ramsar identifies wetlands of international importance, especially those providing waterfowl habitat.

As of 2016, there were 2,231 Ramsar sites, protecting 214,936,005 hectares (531,118,440 acres), and 169 national governments are currently participating.

Rocky shore

A rocky shore is an intertidal area of seacoasts where solid rock predominates. Rocky shores are biologically rich environments, and are a useful "natural laboratory" for studying intertidal ecology and other biological processes. Due to their high accessibility, they have been well studied for a long time and their species are well known.

Roebuck Bay

Roebuck Bay is a bay on the coast of the Kimberley region of Western Australia. Its entrance is bounded in the north by the town of Broome, and in the south by Bush Point and Sandy Point. It is named after HMS Roebuck, the ship captained by William Dampier when he explored the coast of north-western Australia in 1699. The Broome Bird Observatory lies on the northern coast of the bay.

Sarah Martha Baker

Sarah Martha Baker D.Sc. F.L.S. (1887–1917) was an English botanist and ecologist who is remembered for her studies of brown seaweeds and zonation patterns on the seashore.


Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun, and the rotation of the Earth.

Tide tables can be used for any given locale to find the predicted times and amplitude (or "tidal range"). The predictions are influenced by many factors including the alignment of the Sun and Moon, the phase and amplitude of the tide (pattern of tides in the deep ocean), the amphidromic systems of the oceans, and the shape of the coastline and near-shore bathymetry (see Timing). They are however only predictions, the actual time and height of the tide is affected by wind and atmospheric pressure. Many shorelines experience semi-diurnal tides – two nearly equal high and low tides each day. Other locations have a diurnal tide – one high and low tide each day. A "mixed tide" – two uneven magnitude tides a day – is a third regular category.Tides vary on timescales ranging from hours to years due to a number of factors, which determine the lunitidal interval. To make accurate records, tide gauges at fixed stations measure water level over time. Gauges ignore variations caused by waves with periods shorter than minutes. These data are compared to the reference (or datum) level usually called mean sea level.While tides are usually the largest source of short-term sea-level fluctuations, sea levels are also subject to forces such as wind and barometric pressure changes, resulting in storm surges, especially in shallow seas and near coasts.

Tidal phenomena are not limited to the oceans, but can occur in other systems whenever a gravitational field that varies in time and space is present. For example, the shape of the solid part of the Earth is affected slightly by Earth tide, though this is not as easily seen as the water tidal movements.

Tom Levitt

Tom Levitt (born 10 April 1954) is a British Labour Party politician who was the Member of Parliament (MP) for High Peak from the 1997 to 2010 general elections.

Aquatic ecosystems

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