ESTUARY

ESTUARIES

WHAT IS ESTUARYLatin, Aestuarium means tidal part of shore.It is usually found where rivers meet the sea. Estuaries are delicate ecosystem. It can be harmfully affected by pollution, weather, human activities and violation into the habitat of several species of plants and animals.It is a semi-enclosed portion of ocean that is somewhat isolated by land and in which freshwater and salt water mix. More than two thirds of the fish and shellfish we eat is harvested on some parts of estuaries.

Estuary is another name for bay, sound, inlet, harbor, lagoonfreshwater estuaries are created when a river flows into a freshwater lake.Freshwater estuaries are not affected by tides,Estuariesare among the most productive marine ecosystems with high biomass of benthic algae, seagrass and phytoplanktonNutrientsare imported from land, but also retained within the estuarySequence of communities: saltmarsh, seagrass bed, mudflat/sand, pelagicPartially enclosed by reefs, barriers Island or fingers of land. The most productive ecosystems on Earth, containing more life.Estuaries are known as the nurseries of the sea, as their sheltered waters are perfect for spawning. Many marine animals depend on estuaries at some point.Salt marsh grasses and other estuarine plants help prevent pollution and erosion, floods and stabilize our shoreline. In addition on creating the food web for the altitudes of fish birds and mammals

Estuaries differ from other Oceanic environments by:Depth Estuaries are shallow compared to ocean.Salinity varies with tides and season. In the Philippines, flooding during typhoons and rainy season can influence the salinity of Estuaries because of an increased river run-off from the uplands.Temperature is influenced by the: a) depth of the estuaries,b) Tidal currents; c) different seasons for example during winter, ice may form in the water. In most of Asia and the Philippines where seasons are mostly wet and dry, rainy season and dry season can influence the temperature of the estuaries that will also affect the inhabitants in it.

1. Saltmarsh Community (intertidal)Saltmarsh Community (intertidal) Dominated by marshgrasses (flow- ering plants) as high as 2 m, which trap nutrient-rich sedimentsmost plant tissues are not grazed but get into detrital food webslow decay and deep sediment, saltmarshes growh upwards, eventually filling the estuary and becoming land

2. Seagrass bed (inter- to subtidal)Eelgrass (temperate) and Turtlegrass (tropical)few seaweeds, which do not grow well on muddy sedimentmany epiphytic diatoms on seagrass contribute to primary production and serve as food for snailshabitat for sessile animals (hydroids)seagrass biomass ends up in detritusmanatees and sea turtles graze Turtlegrass

3. Mud/SandflatsPrimary producers: epipsammic algae, mostly benthic diatoms and dinoflagellatescyanobacteria mats on mudflatsproduction 10% or less of seagrass beds and saltmarshes, decreasing with grain size of sediment (mud more productive than sand)macro- and meiobenthos, often detrivores, living of deposits from seagrasses and marshesbirds important grazers

4. Plankton CommunityHigh production by nutrients imported by the freshwater inflowHighest production and biomass at intermediate salinities. At head of estuary, nutrient concentrations are high but turbidity by sediments suspended in river water is high as well so that phytoplankton remains light-limited; as sediments sink out of the water column along the river plume and water turbidity decreases, phytoplankton can make use of high nutrient concentrations at intermediate salinities.benthic filter-feeders profit from plankton productionhigh sedimentation of plankton from estuarine plumes can cause oxygen consumption and anoxic sediments at the seaward edge (even hypoxia in the water; for example Mississippi River plume)

5. MangrovesMangroves replace saltmarshes in tropical regions (60-75% of tropical and subtropical coastlines), upper tidal zoneHigh salinity tolerance: broad distribution from high in the estuary to almost fully marine water, but wave-protected zoneMangroves: 12 genera, 60 species of flowering, terrestrial trees and shrubs restricted to mangrove swamps; shallow and far-reaching roots; airial roots help in oxygen supply because the sediments are anoxic;Viviparous growth: seeds germinate on the tree, and young plants fall into the water

Ecological importance:

*Host and feed breeding birds.*protect shoreline from erosion during tropical storms.*important fisheries and supply (boat and fire wood) in native people.

Classification of Estuaries Coastal plain estuaries are created when sea levels rise and fill in an existing river valley.Tectonic activity estuaries, the shifting together and rifting apart of the Earth's crust, creates tectonic estuaries.Bar-built estuaries happens when a lagoon or bay is protected from the ocean by a sandbar orbarrier island,Fjord estuaries are a type of estuary created by glaciers.List of some Estuaries in the Philippines

REFERENCE(www.epa.gov//estuaries)(National Oceania and Atmospheric Administration (NOAA), U.S. Department of Commerce)(core.ecu.edu/geology/woods/estuariesl.htm)