Hasan Fazli

Bio: Hasan Fazli is an academic researcher from Pukyong National University. The author has contributed to research in topics: Population & Clupeonella. The author has an hindex of 12, co-authored 49 publications receiving 517 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.

Population ecological parameters and biomass of anchovy kilka Clupeonella engrauliformis in the Caspian Sea

Abstract: Through most of the last century, three endemic kilka species supported major commercial species in the Caspian Sea. It is clear that catches and abundance of all species have changed, but catch and sampling data are limited and stock assessments are inadequate. Recent changes in the Caspian Sea ecosystem have occurred as a consequence of climatic environmental change (sea level change) and ecologic change caused by the invasive ctenophore Mnemiopsis leidyi. This paper examines the effects of these changes on the population biology and biomass of anchovy kilka Clupeonella engrauliformis in Iranian waters of the Caspian of catch, length-weight relationship, von Bertalanffy growth parameters, condition factors, sex ratios, maturity stages determined from ovarian analysis, natural and fishing mortality, age at first capture, and spawning biomass. The instantaneous coefficient of natural mortality was estimated as 0.473/year and the instantaneous coefficient of fishing mortality varied during the 10-year period between 0.541 and 2.690/year. Biomass of anchovy kilka declined from about 186000 t in 1996 to less than 12000 t in 2004. Recent high fishing rates were not sustainable after the introduction of Mnemiopsis, so overfishing is part of the explanation for the collapse of anchovy kilka in the Caspian Sea.

Suitability indices and habitat suitability index model of Caspian kutum ( Rutilus frisii kutum ) in the southern Caspian Sea

Abstract: The relationship between species and habitat is important in ecosystem-based fisheries management. Habitat suitability index (HSI) modeling is a valuable tool in ecology and can be used to describe the relationship between fish abundance and ecological variables in order to estimate the suitability of specific habitats. In the present study, an HSI model was applied to determine suitable habitats for the Caspian kutum (Rutilus frisii kutum), an important commercial species in the southern Caspian Sea. An arithmetic mean model (AMM) was found to be the most appropriate model for describing the relationship between two of the environmental variables investigated (depth and benthos biomass). However, a geometric mean model explained the evident relationship when all four environmental variables were used (depth, benthos biomass, photosynthetically active radiation and sea surface temperature). The areas with an HSI > 0.5 had over 85 % of the total catch indicating the reliability of the prediction of the Caspian kutum habitat using the AMM. The present study showed that depth and substrate structure are the most important environmental variables for the Caspian kutum to select its habitats, and between remotely sensed data, chlorophyll a, photosynthetically active radiation and sea surface temperature are the most critical parameters for near real-time prediction of the Caspian kutum habitat.

Computation And Interpretation Of Biological Statistics Of Fish Populations

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Ecology of fishes

Abstract: In this course, taught at the Pymatuning Laboratory of Ecology in northwest Pennsylvania, students will explore the population, community, and ecosystem ecology of fishes. We will conduct field investigations in streams, lakes, and marshes. Students will attend background lectures, conduct experiments and field surveys, participate in data collection and analysis, and gain experience in the interpretation and presentation of results. We will learn how to integrate math, physics, chemistry, and biology in our study of fishes. In addition, we seek to expose students to current research in fish ecology. Students will participate in the design of experiments, data analysis, and hone their presentation skills. Most importantly, they will leave the course with a greater knowledge of and appreciation for Pennsylvania’s rich diversity of fishes.

Analysing ecological data

Abstract: By Alain F. Zuur, Elena N. Ieno and Graham M. Smith, New York, Springer, 2007, xxvi + 672 pp., £54.00 or US$84.95 (hardback), ISBN 978-0-387-45967-7 As stated in the preface, finding a suitable and...