LeeDeltas

Deltas

A delta is essentially a land mass formed at the mouth of a river that flows into the ocean, lake, or other large body of water. In the case of many deltas, a freshwater river flows into a salt based body of water, such as an ocean, creating a unique ecosystem consisting of organisms that thrive in both saltwater and freshwater environments. (7)
 * What is a delta?**






 * Organisms that commonly reside in Delta habitats: **

__**Microscopic Organisms:**__ 1. Copepods. These are microscopic crustaceans found both in the ocean and most freshwater ecosystems. They are typically major food sources for small fish and other aquatic vertebrates. Most are benthic, with a smaller percentage being free floating. (5) 2. Green algae, found in freshwater environments, are photosynthetic. (4) 3. Zooplankton

__**Free Floating Organisms:**__ 1. Frogs 2. Fish - flathead mullets - consume detritus (Nile Delta) (6) - soles (Nile Delta) (6) - denticle herring - consume algae and plankton (Niger Delta) (10)



3. Reptiles - (6) - Nile Monitor - Carnivore/Heterotoph/Consumer - Crocodiles (until recently the Nile Crocodile was found in the Nile Delta region) - Carnivore/Heterotoph/Consumer - tortoises - herbivore or omnivore/Heterotoph/Consumer - turtles - herbivore or omnivore/Heterotoph/Consumer

4. Birds - - little gull - (Nile Delta) (6) Omnivore, Heterotroph, Consumer - Peregrine Falcon - (Lena Delta) (9) Carnivore, Heterotroph, Consumer - black brant - (Lena Delta) (9) Herbivore,Heterotroph, Consumer

__**Benthic Organisms: (1)**__ 1. Meiofauna - microscopic crustaceans found in both freshwater and saltwater (Fly and Amazon Deltas) 2. Macrofauna - same as meiofauna, except slightly larger in size (Fly and Amazon Deltas) 3. Oysters/Clams

1. Local plant species- - Pistia (Nile Delta) (2)
 * __Producers/Protists/Plants:__**



- Nymphaea lotus (Tiger Lotus) (Nile Delta) (2)



2. Green Algae (4)



3. Phytoplankton

=**Food Web ** =


 * Geographic Locations **



=Abiotic Factors = Salinity - The freshwater and saltwater mix in almost all Delta based ecosystems is what makes the many different species of organisms able to live there. A change or shift in the concentration of salt water or freshwater could upset the entire ecosystem.

Temperature/Climate - Temperature varies, but most deltas are located in mildly warm climates with hotter summers. For example, in the Nile Delta Region, temperatures range from 10-19 degrees celsius. At its hottest, it can be as much as 30 degrees celsius. Most animals and plants local to delta areas thrive because they only live in areas with a particular temperature or climate. The average rainfall has a particular effect on the entire ecosystem. A specific river height is needed in order for a lot of land based organisms that live in and around water, including amphibians. The climate also is particularly important for birds,as any dramatic climate change will cause a migration and suddenly upset the food web/chain.

Soil/Sediment- affects plants, producers, and small crustaceans. If this is upset then plants will die off, setting off a chain reaction along the food chain, causing other organisms to suffer and/or die. The right soil level and type allows specific plant life and microscopic life to flourish.

=**Potential Threats ** = -Surface Water Abstraction- essentially water from rivers being heavily tapped for human use -Large cities. For example: 80 million people live in the Nile Delta Region, and Alexandria is located on the river along with several other large cities.(6) -Erosion: the Nile Delta has been eroding for a number at years, currently at 50km^2 per year. At that current rate, the Delta will disappear by the year 2550.(6) -Oil and natural gas drilling- It was recently discovered that somewhere around 223 trillion cubic feet of natural gas has been said to be "recoverable" in the Nile Delta Basin.(3) -Both industrial and domestic waste disposal - pollution from pesticides and fertilizers has been discovered in the delta region of the Lena River (9) -Water diversion - this has been put into effect for irrigation in Russia in the Lena Delta Region (9)

=**Endangered Species: ** = Pygmy Hippo- located in the Niger River Delta region (10)



Indus River Dolphin - "one of the world's rarest mammals and most endangered cetaceans," an estimated 1,000 or less are still alive only in the Indus River. (8)



**Personal Reflection:**

Deltas themselves are of huge importance to humans. These highly fertile regions abundant with both plant and animal life serve as a medium between freshwater and seawater ecosystems. Deltas represent the border between two completely different aquatic environments, and that can be seen in the wide variety of organisms that make their habitats in deltas. There are only so many deltas in the world, and each one is unique.

=**Sources:**=

1. Alongi, D. M., and A. I. Robertson. "Factors regulating benthic food chains in  tropical river deltas and adjacent shelf areas." ////SpringerLink////. N.p., n.d. Web. 8 Sept. 2010. .

2. Unknown. "Freshwater Ecoregions of the World." Freshwater Ecoregions of the  World. World Wildlife Fund/The Nature Conservancy, 26 Aug. 2010. Web. 9 <span style="font-family: Arial,Verdana,sans-serif; font-size: 11px; line-height: normal; white-space: nowrap;"> Sept. 2010. <http://www.feow.org/ecoregion_details.php?eco=524>.

<span style="font-family: Arial,Verdana,sans-serif; font-size: 11px; line-height: normal; white-space: nowrap;">3. - - -. "Nile Delta Natural Gas Potential Is Significant." Science Daily. Science <span style="font-family: Arial,Verdana,sans-serif; font-size: 11px; line-height: normal; white-space: nowrap;"> Daily, 25 May 2010. Web. 9 Sept. 2010. <http://www.sciencedaily.com/ <span style="font-family: Arial,Verdana,sans-serif; font-size: 11px; line-height: normal; white-space: nowrap;"> releases/2010/05/100524130842.htm>.

4. <span style="font-family: Arial,Verdana,sans-serif; font-size: 11px; line-height: normal; white-space: nowrap;">Van Egmond, Wim. "Green Algae." Microscopy UK. Microscopy UK, n.d. Web. 9 Sept. <span style="font-family: Arial,Verdana,sans-serif; font-size: 11px; line-height: normal; white-space: nowrap;"> 2010. <http://www.microscopy-uk.org.uk/mag/ <span style="font-family: Arial,Verdana,sans-serif; font-size: 11px; line-height: normal; white-space: nowrap;"> indexmag.html?http://www.microscopy-uk.org.uk/mag/wimsmall/green.html>.

<span style="font-family: Arial,Verdana,sans-serif; font-size: 11px; line-height: normal; white-space: nowrap;">5. Various authors. "Copepod." WIkipedia. Wikimedia, 1 Sept. 2010. Web. 6 Sept. <span style="font-family: Arial,Verdana,sans-serif; font-size: 11px; line-height: normal; white-space: nowrap;"> 2010. <http://en.wikipedia.org/wiki/Copepod>.

<span style="font-family: Arial,Verdana,sans-serif; font-size: 11px; line-height: normal; white-space: nowrap;">6. - - -. "Nile Delta." Wikipedia. Wikimedia, 21 Aug. 2010. Web. 5 Sept. 2010. <span style="font-family: Arial,Verdana,sans-serif; font-size: 11px; line-height: normal; white-space: nowrap;"> <http://en.wikipedia.org/wiki/Nile_Delta>.

<span style="font-family: Arial,Verdana,sans-serif; font-size: 11px; line-height: normal; white-space: nowrap;">7. - - -. "River delta." Wikipedia. Wikimedia, 7 Sept. 2010. Web. 10 Sept. 2010. <span style="font-family: Arial,Verdana,sans-serif; font-size: 11px; line-height: normal; white-space: nowrap;"> <http://en.wikipedia.org/wiki/River_delta>.

<span style="font-family: Arial,Verdana,sans-serif; font-size: 11px; line-height: normal; white-space: nowrap;">8. - - -. "WWF - Indus River Delta." World Wildlife Fund. N.p., n.d. Web. 10 Sept. <span style="font-family: Arial,Verdana,sans-serif; font-size: 11px; line-height: normal; white-space: nowrap;"> 2010. <http://wwf.panda.org/about_our_earth/ecoregions/ <span style="font-family: Arial,Verdana,sans-serif; font-size: 11px; line-height: normal; white-space: nowrap;"> indus_river_delta.cfm>.

<span style="font-family: Arial,Verdana,sans-serif; font-size: 11px; line-height: normal; white-space: nowrap;">9. <span style="font-family: Arial,Verdana,sans-serif; font-size: 11px; line-height: normal; white-space: nowrap;">- - -. "WWF - Lena River Delta." World Wildlife Fund. N.p., n.d. Web. 10 Sept. <span style="font-family: Arial,Verdana,sans-serif; font-size: 11px; line-height: normal; white-space: nowrap;"> 2010. <http://wwf.panda.org/about_our_earth/ecoregions/ <span style="font-family: Arial,Verdana,sans-serif; font-size: 11px; line-height: normal; white-space: nowrap;"> lena_river_delta.cfm>.

<span style="font-family: Arial,Verdana,sans-serif; font-size: 11px; line-height: normal; white-space: nowrap;">10. - - -. "WWF - Niger River Delta." World Wildlife Fund. N.p., n.d. Web. 9 Sept. <span style="font-family: Arial,Verdana,sans-serif; font-size: 11px; line-height: normal; white-space: nowrap;"> 2010. <http://wwf.panda.org/about_our_earth/ecoregions/ <span style="font-family: Arial,Verdana,sans-serif; font-size: 11px; line-height: normal; white-space: nowrap;"> niger_river_delta.cfm>.