Reza Pourgholam

Bio: Reza Pourgholam is an academic researcher. The author has contributed to research in topics: Mnemiopsis & Phytoplankton. The author has an hindex of 8, co-authored 23 publications receiving 340 citations.

Changes in biodiversity of phytoplankton, zooplankton, fishes and macrobenthos in the Southern Caspian Sea after the invasion of the ctenophore Mnemiopsis Leidyi

Abstract: Monitoring for 6 years (2001–2006) showed that the population explosion of the alien ctenophore Mnemiopsis leidyi in the southern Caspian Sea coincided with a decline in the abundance and species number of mesozooplankton. While this decline appeared to have reduced the nourishment of sprat (also known as kilka), it seemed to have affected phytoplankton favorably mainly due to the decrease in grazing pressure. During 2001–2002, when M. leidyi abundance and biomass were at their highest levels, abundance of dinoflagellates and cyanophytes exceeded that of diatoms. Before the invasion (1996) and in some years after the invasion (2003, 2004 and 2006) diatom abundance was higher than the abundance of other groups. In September 2005, an unprecedented bloom of the toxic cyanophyte Nodularia sp. was observed in the southern Caspian Sea. Disappearance of edible zooplankton such as Eurytemora spp. was among the first changes observed after the expansion of M. leidyi in the area. Some changes in the macrobenthic fauna were also conspicuous after the increase of this ctenophore. While the biomass of some deposit feeders, such as the polychaete Nereis diversicolor and oligochaete species increased, benthic crustaceans decreased sharply in abundance during 2001–2003 and completely disappeared during 2004–2006. Iranian catches of kilka, the most abundant and widespread zooplanktivorous fish, decreased significantly in the southern Caspian Sea after 1999. Iranian landings of kilka dropped ~70% from 69,070 ± 20,270 t during 1995–2000 to 23,430 ± 12,240 t during 2001–2006, resulting in a loss of at least 125 million US dollars to the economy. There were also changes in the total catches of large predators such as the kutum and mullet, which mainly feed on kilka, between 1991 and 2006.

The Environmental Effect on Spawning Time, Length at Maturity and Fecundity of Kutum (Rutilus frisii kutum, Kamensky, 1901) in Southern Part of Caspian Sea, Iran

Abstract: Fish sampling were carried out using beach seines during the fishing season from early October 2006 to mid April 2007. The gonadosomatic indexes (GSI) in range and average for female and male were 0.03 to 40.28 (5.70 ± 6.48) and 0.13 to 16.71 (3.39 ± 2.33), respectively. The GSI indicated that the reproductions of R. f. kutum were occurred during March-April, with the highest average value of 6.52 for males and of 17.00 for females in April. Fifty percent of length maturity (L ) at FL = 37.78 cm was recorded. The absolute fecundity ranged from m50% 15,723 for a three-year old to 130,737 eggs for an eight-year old female, with a mean of 60435 ± 24889. The relationship between fecundity (F) and fork length (cm) was represented by the formula: Fec. = 6616FL+25916. The von Bertalanffy growth parameters was: L =67.5cm, K=0.21 year , t =-0.10 for throw population of kutum. 8 0 1 The maximum spawning migration into the rivers based on GSI occurred significantly in April but it be affected by environment of sea water layers. The results showed that the length at first maturity and fecundity of R. f. kutum reduced in southern part of Caspian Sea.

The Design and Analysis of Experiments

Abstract: THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

Computation And Interpretation Of Biological Statistics Of Fish Populations

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Increasing jellyfish populations: trends in Large Marine Ecosystems

Abstract: Although there are various indications and claims that jellyfish (ie, scyphozoans, cubozoans, most hydrozoans, ctenophores, and salps) have been increasing at a global scale in recent decades, a rigorous demonstration of this has never been presented Because this is mainly due to scarcity of quantitative time series of jellyfish abundance from scientific surveys, we attempt to complement such data with non-conventional information from other sources This was accomplished using the analytical framework of fuzzy logic, which allows the combination of information with variable degrees of cardinality, reliability, and temporal and spatial coverage Data were aggregated and analyzed at the scale of Large Marine Ecosystem (LME) Of the 66 LMEs defined thus far that cover the world’s coastal waters and seas, trends of jellyfish abundance after 1950 (increasing, decreasing, or stable/variable) were identified for 45, with variable degrees of confidence Of those 45 LMEs, the majority (28 or 62%) showed increasing trends These changes are discussed in the context of possible sources of bias and uncertainty, along with previously proposed hypotheses to explain increases in jellyfish