PIAHSProceedings of the International Association of Hydrological SciencesPIAHSProc. IAHS2199-899XCopernicus PublicationsGöttingen, Germany10.5194/piahs-374-113-2016Hydrology and water resources in Caspian SeaHaddadi MoghaddamKouroshkhkhmoghadam@gmail.comInternational Sturgeon Research Institute (ISRI), P.O. Box 41635-3464, Rasht, IranKourosh Haddadi Moghaddam (khkhmoghadam@gmail.com)17October2016374113116This work is licensed under a Creative Commons Attribution 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by/3.0/This article is available from https://piahs.copernicus.org/articles/374/113/2016/piahs-374-113-2016.htmlThe full text article is available as a PDF file from https://piahs.copernicus.org/articles/374/113/2016/piahs-374-113-2016.pdf
Precipitation is the main driver of the water balance variability of the
water over space and time, and changes in precipitation have very important
implications for hydrology and water resources. Variations in precipitation
over daily, seasonal, annual, and decadal time scales influence hydrological
variability over time in a catchment. Flood frequency is affected by changes
in the year-to-year variability in precipitation and by changes in short-term
rainfall properties. Desiccation of the Caspian Sea is one of the world's
most serious ecosystem catastrophes. The Persian Sturgeon (Acipenser persicus) caught under 10 m depth using bottom trawl net by research vessel
during winter 2012, summer and winter 2013 and spring 2014 in east, central
and west of southern parts of Caspian Sea, then, their diets were
investigated. During 136 trawling in the aimed seasons, Persian sturgeon with
1 to 2 years old and 179.67×0.2 g (body weight) and 29.97±0.4 cm (Total length) captured. Examination of stomach contents in the
sturgeon specimens revealed that the food spectrum was composed of bony
fishes (Neogobius sp., Atherina sp. and Clupeonella delicatula), invertebrates belonging to the family Ampharetidae polychaeta
worms including (Hypanai sp. and Nereis diversicolor),
various crustaceans (Gammarus sp. and Paramysis sp.).
Investigation on stomach contents of sturgeon Acipenser persicus
caught under 10 m depth in 2012 to 2013 surveys showed that there is
significant difference in the consumed food. The most food diversity have
been observed in winter 2013, also Polychaeta is the primary consumed food
and crustacean is the secondary one (P>0.05), no new types of
food (such as bony fishes or benthics) have been observed on food chain of
Acipenser persicus and shows no significant difference
(P>0.05).
Number, seasons and means body weight (BW), total length (TL) and
condition factor in Persian Sturgeon (Mean ± SD).
Mean condition factorMean Total length (cm)Mean body weight (g)SeasonsNumber0.31±0.0125.5±0.4348.9±0.6Winter 2012410.75±0.2535.07±0.8322.64±0.3Summer 2013200.48±0.0825.91±0.1294.81±0.7Winter 2013320.38±0.0733.4±0.452.34±0.3Spring 201415Introduction
Prey abundance, feeding and food habits are important issues for both
effective Caspian Sea fisheries management and conservation biology in
aquatic environment, so Sturgeons one the most important and valuable fishes
in the world and Caspian Sea is one of their most important habitat's which
90 % of total world Caviar belongs to it (Ivanov et al., 1999). In recent
years sturgeon stock and catch has been decreased in their most important
habitats (Pourkazemi, 1996; Ivanov et al., 1999; Moghim et al., 2006).
Biological and feeding factors have great influence an sturgeon catch to
determine these factors, we should investigate on sturgeon feeding
competition and other relations between different habits of fishes in various
places and time is of high importance (Moghim et al., 2006) therefore should
navigate the previous studies of researchers in this regards. Initial studies
carried out on sturgeon feeding in north, middle and south Caspian Sea
(Shorygin, 1937; Salnikov et al., 1975; Begenal, 1978; Moiseev and Filatova,
1988 and Polyaninova and Molodtseva, 2002). During sturgeon stock assessment
at southern part of Caspian Sea in 2006 to 2008, diets of Persian sturgeon
investigated in different depths and various seasons. Although some studies
conducted in Iran up to now, they were cyclical (Kashentseva, 2005; Hashemyan
et al., 2005) considering that too ecological changes happened in Caspian Sea
(Haddadi Moghaddam et al., 2003; Roohi et al., 2007) the previous studies
don't include all dietary information of sturgeon. So, the aims of the study
were (i) determine seasonal change on Persian sturgeon (ii) determine more
details on sturgeon food composition and identification of food index to
better understand Persian sturgeon feeding condition.
Materials and methods
The study carried out during March, February 2012, March, February 2013,
July, August 2013 and April, May 2014. According to the area of regions, 34
station selected through stratified random sampling design (including 21
stations in east, 5 stations in middle and 8 station in west). The sampled
stations were located between (32∘2′ N, 50∘29′ E
and 37∘2′ N , 53∘4′ E).Trawling
conducted in each trawling, GPS and map with scale (1, 100 000) used to
determine swept distance and geographical conditions of stations. Also
bottom trawl (trawl with 9 m upper rope) and research vessel (250 hsp) were
applied in this regard.
During days for 30 min (07.00–16.00) in each station and the speed was
25 to 3 Knots along the coast .After catching and measuring of mean total
length and body weight, the digestive system of samples removed (Tavakoli et
al., 2007) In order to remove the digestive tract, an anal incision created
along the middle ventral line up to gill. So, the digestive system removed
completely from ventral region (Chugunova, 1963).
Fish diets were determined from stomach contents and the ingested food
evaluated by enumeration (Biswas, 1993). The manual for Caspian Sea
invertebrate identification key applied for identifying primary and secondary
foods in stomach content (Pryshtin et al., 1988). For sturgeon diet
assessment, prey items were taxonomically classified and four indices – the
prey occurrence index F (%), the prey frequency index Cn (%), gastro
somatic index GSI (%) and condition factor (CF), were calculated as
follows:
F (%) =100×(Np/Ni) where
Np= the number of stomachs with a specific prey
Ni= the total number of non-empty stomachs. Values of
(F>50 %) indicate main prey;
10 % < F < 50 %, secondary food items; and F < 10 %, occasional prey and
Cn (%) =100×(Ni/Np)
Ni= is the number of the prey item in all nonempty stomachs
Np= the total number of food items in all stomachs in a sample
GSI (%) =100×(Ws/Wc)
Ws= weight of stomach
Wc= weight of carcass (g)
CF = W/TL3
W= weight (g)
TL = total length (cm) (Euzen, 1987; Saborowski and Buchholz, 1996).
Results
The diet of megrim is based on benthic, teleosts and bottom, Crustacea and
polychaeta. In this study different foods observed in Persian sturgeon
stomach including various teleosts such as Neogobious sp.,
Atherina sp., Clupeonella cultriventris and benthic invertebrates
like Ampharitidae (Hypania sp. and Hypaniolla sp.) Nereis diversicolor, Crustacean
(Paramysis sp. and Gammarus sp.). In this case 115 immature Persian Sturgeons
in 1 to 2 years old captured for feeding examination 90 % of caught
sturgeon had food in stomach. comparative study of condition factor in
sturgeon caught under 10 m depth showed the highest condition factor in
eastern region (0.75±0.25) in summer 2013 and the lowest one (0.26±0.13) in western region of Southern part of Caspian Sea in spring.
The results showed no significant differences in condition factor of Persian
sturgeon (P>0.05) (Table 1).
GSI comparison in Persian sturgeon during different seasons showed that the
mean GSI of Persian sturgeon was highest in winter 2013 (109.6±14.7)
and lowest (51.83±3.8) in summer 2013. The results showed no
significant difference in GSI in various regions and seasons (P>0.05). Investigation of food frequency percent showed that Persian sturgeon
used crustacean as basic food in winter 2012, but in order seasons consumed
teleostes as secondary food. Statistical results indicate that there is not
significant difference in the foods consumed in different seasons and
regions (P>0.05) (Table 2).
Coastal zone is important nursery habitats for many fishes where they can
feed upon a concentrated food supply. Study on frequency and type of
consumed prey in Persian sturgeon shows no regular pattern in their feeding
behaviour under 10 m depth and Ampharitidae is their primary food. This could
be due to unavailability of their food resources and factors like depth,
temperature, type of bed and organic material rate. Teleosts consist the
basic parts of food consumed by younger fishes (Hashemyan et al., 2005;
Mirzajani et al., 2003; Holchick, 1989). But in lower ages considering the
depth and environment geographical, conditions, polychaeta consumed by
sturgeon. Examination of feeding intensity during recent surveys do not show
any type of new food, but the rate and percent of ingested food has been
changed and increased during warm seasons. Although factors such as type of
bed, organic material rate and physico-chemical conditions can influence on
feeding variety in aquatics (Holchick, 1989; Tavakoli et
al., 2007; Gegadeesan and Ayyakkannu, 1992; Waldman, 1995). Basic changes
occurred in ecological condition of Caspian Sea, which is due to increase in
Caspian Sea water level up to 2.2 m from 1995 and elevation of oxygen level
because entering urban and industrial pollution that leads to slugging of
bed. These factors caused to specialization of food for some species and
more large preys such as various species of teleosts observed in sturgeon
stomach contents (Salnikov et al., 1975). Regarding these changes and new
ecological condition of Caspian Sea, The results of study don't indicate any
new feeding condition for Persian sturgeon. According to studies carried out
under 10 m depth in east, middle and west of southern part in Caspian
Sea (Gasemove, 1994) and considering the gradual warming of Caspian Sea
water, it was determined that Sturgeon like to use larger preys which
influence on the SI and condition factor of one's caught in warm seasons.
Teleosts and benthic diversity become warmer seasons of year. Factors such
as food frequency in region, food resources and population have the most
influence on feeding rate and condition factor in these fishes (Nikolskii,
1963). Studies conducted on SI in 300 Persian sturgeon in eastern, northwest
and south parts of Caspian Sea (Salnikov et al., 1975; Zolotarev et al.,
1996) showed that SI was higher when Sturgeon consumed teleosts. The changes
may be due to competition for using different types of food, sea waves and
type of bed that fish inhabited (Graber, 1990; Kostyuchenko, 1994;
Chechun, 1998). Study on variety in winter 2013 and spring 2014 is more than
other seasons, which may be due to change in southern parts of Caspian Sea
showed similar results by Cortest and Graber (1990). These modifications
reflected changes in the availability of prey which influenced fish diet
composition and were probably related to the loss of biodiversity in the
Black Sea benthic communities which became dominated by some opportunistic
species like polychaetes by Gomoiu et al. (2004).
Data availability
Analyses of Variance (ANOVA) were performed using the STATISTICA 6.1 program
applied for data availability. The results identified by _SD and seasonal
changes in stom ach content of Persian sturgeon determined by relative
frequency. All statistical analyses were carried SAS version 9.0 software
(SAS Institute, inc., USA).
Acknowledgements
This study is part of a project entitled “sturgeon stock assessment in
southern parts of Caspian Sea” that was conducted with financial support of
Iranian Fishes Research Organization (IFRO) at International Sturgeon
Research Institute (ISRI). We would like to thank all the colleagues who
helped and supported us in obtaining Persian sturgeon from Caspian Sea with
the grant agreement number: 48/689.
References
Begenal, G.: Methods for assessment for fish production in freshwater, Blackwell
science public, UK, 190–194, 1978.
Biswas, S. P.: Manual of Methods in Fish Biology, South Asian Publication, New
Delhi, India, 89, 23–25, 1993.Cortest, E. and Graber, S. H.: Diet and feeding habits and estimates of daily
ration of young, Negaprionbrerirostris (Poey), CopelaBul, UK, 4, 204–218, 1990.
Chechun, T. Ya.: Nutrition of the Acipenseridae of the Sea of Azov under
Present Conditions, J. Appl. Ichthyol., 38, 155–158, 1998.
Chugunova, N. I.: Age and Growth Studies in Fish, Biol. Bul., 7, 201–210,
1963.
Euzen, O.: Food Habits and Diet Comparison of Some Fish of Kuwait, Biol.
Bull., 58, 11–20, 1987.
Gegadeesan, P. and Ayyakkannu, K.: Seasonal variation of benthic fauna in
marine zone of Coleroon estuary inshore water, southeast coast of India,
Mar. Sci., 15, 223–229, 1992.
Gasemove, F.: Animals and biotic productions of Caspian Sea, Iranian
fisheries publication, Iran, 450–455, 1994.
Gomoiu, M. T., Secrieru, D., Paraschiv, G., Opreanu, P., and Puschiaza,
D.: Someremarks on the ecological state of benthic populations recorded
during the IAEA, Mar. Geol., 9, 12–20, 2004.
Haddadi Moghaddam, K., Parandavar, H., Pajand, Z.,
Khoshghalb, M. B., Chubian, F., and Jooshideh, H.: Study on feeding
habits of sturgeons in the Caspian Sea up to 10 m depth (Guilan-Province),
Iranian fisheries Research Organization
publication, Iran, 69–73, 2003.
Hashemyan, A., Khoshbavar, H. A., Rostami, R., and
Taleshian, H.: A comparative analysis of feeding habits of sturgeon fish in
shallow coastal waters of Mazandaran and Golestan provinces, south Caspian
Sea, J. Fisheries Sci., 14, 157–166, 2005.
Holchick, M.: The fresh water fishes of European. Iranian fisheries Research
publication, Iran, 401–422, 1989.
Ivanov, V. P., Vlasenko, A. D., Khodorevskaya, R. P., and Raspopov, V. M.:
Contemporary status of Caspian sturgeon (Acipenseridae) stock and its
conservation, J. Appl. Ichthyol., 15, 103–105, 1999.
Kostyuchenko, V. A.: Biology and state of fishing of the Sea of Azov
Sturgeon's, J. Appl. Ichthyol., 21, 174–187, 1994.
Kashentseva, L. N.: The status of feeding of stellate Sturgeon population in
the Caspian Sea, status of commercial species stock in the Caspian Sea and
their management, J. Great Lake Res., 4, 23–35, 2005.
Mirzajani, A. R., Yosefzad, E., Sayadrahim, M., and Abdolmaleki, S. H.:
Investigation onmeiofauna and substrate characteristic in the southern
Caspian Sea, J. Fisheries Sci., 11, 98–107, 2003.
Moghim, M., Parafkandeh, F., Tavakoli, M., and Behruz Khoshghalb, M.: Investigation
biological and statistical on sturgeon fish in 2001–2003, Iranian fisheries
Research Organization publication, Iran, 61–65, 2006.
Moiseev, P. A. and Filatova, Z. A.: Animals and Bioproductivity of the
Caspian Sea, Nauka publication Moscow, 105–114, 1988.
Nikolskii, G. V.: The Ecology of Fishes, Cold spring Harbor, New York, 340–345,
1963.
Polyaninova, A. A., and Molodtseva, A. I.: The benthos sturgeon feeding
relationship for the Caspian Sea, J. Ichthyol., 38, 151–157, 2002.
Pourkazemi, M.: Caspian Sea sturgeon conversation and fisheries past,
present and future, J. Appl. Ichthyol., 22, 1–4, 1996.Pryshtin, Y. A., Wingraduva, V. N., Kundakuva, V., Kuna, M. C., and
Vastakhuva, A. V.: Atlas of invertebrates Caspian Sea, Iranian fisheries Research
Organization publication, Tehran, Iran, 345, 1988.
Roohi, A., Naderi, M. F., Vahedi, M., Qasemi, F., Roshantabari, F., Parafkande,
B., Hasanzadekiabi, and Shiganova, T.: Strategy of Mnemoiopsis leidyi
combating in the Caspian Sea, Iranian fisheries Research Organization
publication, Iran, 30–78, 2007.
Saborowski, R. and Buchholz, F.: Annual changes in the nutritive state of
North-Sea, J. Fish Biol., 49, 173–194, 1996.
Salnikov, N. E., Kukuradze, A. M., and Kirilyuk, M. M.: Prospects for Sturgeon
Culture in the Northwestern Black Sea under Conditions of Complex Use of
Water Resources, J. Appl. Ichthyol., 8, 87–94, 1975.
Shorygin, A. A.: Standard methods for water and wastewater, J. Fish.
Biol., 5, 74–85, 1937.
Tavakoli, M., Jooshideh, H., Fadaeei,
B., Keymaram, B., Parafkandeh, M., Moghim, M., Bahmani, H., Parandavar, Z., Pajand,
K., HaddadiMoghaddam, F., Chubian, D., Kor, A., Halajian, F., Chakmeduze,
S., Hasanzadeh, H., Taleshian, and Abassi, K.: Stock assessment of sturgeon
fishes in the Southern part of Caspian Sea (Iranian water), Iranian
fisheries Research Organization publication, Iran, 136–153, 2007.
Waldman, J. R.: Sturgeon and paddle fish Convergence of Biology, politics and
greed, J. Fish. Biol., 20, 20–21, 1995.Zolotarev, P. N., Shlyakhov, V. A., and Akselev, O. I.: Food Supply and Feeding
of the Russian Sturgeon Acipensergueldenstaedtii and the Starred Sturgeon
Acipenserstellatus in the North western Black
Sea under Modern Ecological Conditions, J. Appl. Ichthyol., 36,
357–362, 1996.