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Detecting the Spatial Distribution of Artemia at Urmiea Lake

M. Ahadnejad Reveshty
University of Zanjan, Dept. of Geography
Email: mo_ahadnejad@yahoo.com


Introduction
Artemia is an aquatic crustacean belonging to the subclass of ostracoda, characterized by a bivalve, generally calcified carapace with a hinge along the dorsal margin. It is a fine benthic marine fauna living in saline water, called Artemia Cysts (Brine Shrimp Eggs). Because many ostracoda species have ecological limitations controlled by temperature, salinity, oxygen, food and other factors, they can provide an important tool for pale-oceanographic reconstruction. Artemia is a marine fauna with a very vast geographic extent throughout the world. Presently over 500 different species of artemia have been recognized in 500 different geographic locations. Presently artemia in Iran has been found in 18 different geographic locations in saline lakes and lagoons but Urmia Lake is known as the largest habitat for this fauna. Due to Artemia’s nutritious values it is used as a significant food source for most aquatic fauna as shrimps, caviars, and shells. Annual consumption of Artemia cyst in world aquaculture centers increased from 60 tones in 1980 to 2000 tones in year 1994.

Artemia is a collection of certain sibling species as well as super species differing from each other due to their reproductive isolation. In general two different type of artemia naming bisexual artemia and parthenogentic artemia breed in two different ways as ovoviviparous and oviparous during a year.

Previous Work & Necessity of Research
The first written report concerning the Urmia Artemia was prepared in 1899 by Ghanter. In 1976 another research presented by Clark & Bowen relating Artemia and its breeding condition in Urmia Lake. An extensive research conducted by Dr. Azari Takami in 1992 revealed that Urmia Artemia is certain species unique for Urmia Lake and is different from the others; therefore he named it as Artemia Urmiana. In 2002 concurrent with the establishment of The Artemia Research Center in University of Urmia a lot of researches are conducted in this center. Besides that artemia farming under laboratory conditions is also being experimented in this center.

Temporal and spatial distribution of artemia has been discussed so far using sampling technique while other enhancement techniques as remote sensing and satellite data has not been seriously considered .The present research mainly focuses on enhancement techniques for artemia detection in Urmia Lake using land sat TM data and image processing techniques.

Study Area
Urmia Lake as the largest habitat for artemia and the largest water body in Iranian plateau is located between two major provinces of East Azarbaijan and west Azarbaijan. The lake is bounded between 37 4 - 38 17 latitudes and 45 13 - 46 longitudes. The lake covers an area between 4000- 6000 km2 averaging around 5000 km2. 20 permanent and seasonal rivers as well as a few submarine streams and springs feed the lake. Average salinity of the lake ranges between 220- 300 mg/lit depending upon temporal and spatial conditions .Due to the ecological heritage of Urmia Lake it is recorded as a protected habitat in the world by the United Nations.

Biological Characteristics of Artemia Urmia
Urmia Artemia is one of the seven polygamy species (male and female) yet recognized in the world. The artemia feeds alga and other saprogenic material in the lake. Table 1 compares biometric indices of Artemia Urmiana (male and female) with other artemia throughout the world.


Biometric indices/Location Tanzania China/ Yanshing lake Ghazaghestan Artemia Great salt lake(USA) Urmia Artemia
Male Body length/mm 8.86 10.44 10.16 9.22 12.47
Male Body length/mm 10.99 12.53 11.43 12.51 16.45

Regarding the above table it seems that Urmia Artemia is a unique species totally different from others in terms of its biometric indices. Figure no. 1 shows a picture of Artemia Urmiana.


Fig 1: Picture of Artemia Urmiana (Female & Male)

Artemia breeding happens in two different ways as bisexual and parthenogentic.In a normal condition where the degree of salinity is low (entrances of river and also in rainy seasons) artemia breeds as parthenogentic while under unfavorable condition with an increase in salinity (dry season and inside the lake) breeding occurs as bisexual. The two different breeding ways may occur in Urmia Lake however prominent breeding condition in Urmia Lake is bisexual due to salinity of the lake.

Methodology
Preliminary investigations disclosing distribution of artemia in the lake led to sampling methods. Samplings were done in a few points in the lake. Landsat TM images of 31-6-1989 were used to detect spatial distribution of artemia. Following flow chart shows different steps conducted in this study.


Fig 2: Research flowchart

Multi-spectral ETM data enhances artemia in the lake specially using training samples collected throughout the lake. Contrast stretch techniques were applied when images were corrected for both geometric and radiometric errors. Colure composite images of 432 shows massive like distribution of artemia in the lake concentrated in a few portions throughout the lake.


Fig 3: Artemia distribution in Urmia Lake (Ghobadlu and north of Islamic Island)


Fig 4: Artemia distribution in Urmia Lake, western and southern part of the lake

Spectral profiles of different bands were used for better understanding of artemia reflection in different spectral bands (fig 5 and 6).

Below profiles reveal that Urmia Artemia may be detected in all TM bands but its highest reflection occurs in 1, 4, and 6 which may be interpreted as following:
  1. the first peak is related to band 1( blue band) which has highest penetration in water so artemia may be studied using this band in low water
  2. The second peak belongs to band 4 (near infra- red), this band is most suitable for biomass studies. Due to orange to reddish color of Artemia Urmiana it may be enhanced with high certainty.
  3. The highest peak of artemia reflection occurs in band 6 (thermal band), but it is not recommended for the sake of being thermal band.

Fig5: Artemia reflection profile in different bands (east of lake)


Fig 6: Artemia reflection profile in different bands (south of lake)

Furthermore threshold technique has also been employed for better detection. Finally artemia were enhanced and the image was classified. Fig 7 shows spatial distribution of artemia in the Urmia Lake during the studied time.


Fig 7: spatial distribution of artemia in Urmia Lake (date: 31-6-1989)

Prepared map reveals that artemia in Urmia Lake distributed mostly along coastal zones as well as fresh river junction to the lake, hence it may be concluded that both types of artemia may be living in the lake; in fresh river junctions artemia breeds as parthenogentic and in places away from the coast breeding mode is as bisexual. Also the map shows that artemia has considerably less living possibility in deep water due to increased salinity as well as scarcity of nutritious materials like alga and organic substances.

Conclusion and Sugesstion
The results of this study show the feasibility of using multi-spectral satellite data for artemia detection. The present study only focuses on spatial distribution of artemia. Multi temporal images are needed for temporal distribution study.

Regarding to the Urmia Lake size which is considered as one of the largest habitats of artemia in the world, during every period about 400000 tons of artemia biomass may be harvested from the lake. Also Due to significant role of artemia in aquaculture industry a well prepared planning is needed to extract the potential biomass not damaging the environment. It is obvious such measurements may assist booming the economy of the area. So it is highly recommended to use satellite images for temporal as well as spatial changes of artemia concentration in the lake for planning purposes.

References
  • Jabbarloo Shabostari Bahram “The Urmia Lake tear of Iran nature”, , Naghsh publications, 1374, Tehran.
  • Yarmohammadi Mahtab” Synoptic studies of artemia in Urmia Lake”. Iran Fishery Magazine, no. 1, spring 1381, Tehran.
  • Naser Agh, Farzaneh Nori,” Urmia Lake , artemia and the economy of western Azarbaijan”, The first scientific and technical exhibition, 1376, Urmia.
  • Saber Khodabandeh, Effect of salinity on Artemia urmiana cyst quality (chorion thickness) at laboratory condition” Tarbiat Modarres University, Faculty of Marine Science, 1998, Tehran.
  • Mohammadyari, A; Rahimian, H1; Agh,N2, “Biometry of cyst and nauplii of artemia strains from different geographical origin of iran”1 Dept. of Biology, Faculty of Science, Tehran University, 2,Artemia and Aquatic Animals Research Center, Urmia University, Urmia, Iran .
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