Summary Length–weight relationships were calculated for nine freshwater fish species belonging to two families using 1020 specimens from 15 water sources in the western part of Anatolia, Turkey. This study is the first reference on length–parameters for these species, eight of which are endemic, and with new maximum length records for three of the species.

The abundance and spatial distribution of zooplankton at monthly intervals were studied in polluted Golden Horn Estuary (Istanbul, Turkey), from July 2006 to December 2007. Selected water quality parameters also were measured. The zooplankton community was characterized by the presence of freshwater, estuarine and marine species, with a total of 59 taxa. Rotifers were the most important fraction of the total zooplankton, comprising 36.52% of all the samples. The zooplankton exhibited seasonal patterns, with the highest abundance occurring in the summer (979 ind. L À1 ) and the lowest in the spring (856 ind. L À1 ). Rotifera was the most abundant group in the upper and middle estuary, whereas Copepoda usually reaches the maximum densities in the higher salinity waters in the lower estuary. The study results indicated that both the sampling time (seasons) and sampling sites jointly had significant effects on the zooplankton densities (MANOVA P < 0.05), and horizontal patterns were related to electrical conductivity, water temperature, dissolved oxygen, suspended particulate matter, pH and chlorophyll a measured in the estuary.This study is part of the PhD thesis of Zeynep Dorak, titled 'Influences of abiotic factors on seasonal changes of zooplankton in Golden Horn, Istanbul, Turkey'.

The zooplankton fauna and the relationship with their environmental variables were investigated on the epilimnion layer of the seven reservoirs (Demirdöven, Devegeçidi, Menzelet, Sır, Ömerli, Porsuk, Tahtalı) of different regions (Marmara, Aegean, Mediterranean, Central Anatolia, Eastern Anatolia, Southeastern Anatolia) throughout the summer months (2015) in Turkey. According to the trophic conditions reservoirs varied between oligo-and eutrophic status. Chlorophylla concentration, measured for the estimation of primary production, was determined considerably high along the investigation period. A total of 62 zooplankton species were identified with the contribution of 44 rotifers, nine cladocerans and nine copepods. Except one reservoir, all of the others were dominated by rotifera group, and also in each study site dominant taxa were changed at species level. On the other hand common dominant taxa for all reservoirs was the rotifer Polyarthra vulgaris Carlin, 1943 with 95 % frequency. In terms of zooplankton species, most of the studied reservoirs showed less than 50% similarities, due to their different limnological conditions and different geographic locations. Reservoirs in high trophic conditions in the present study were represented by low species diversity. Water quality in the reservoirs with respect to biological data were determined as ß-mesosaprobic. The using limnological and biological indices to determine water quality were consistent. Densities of main zooplankton groups, and also frequent species of the reservoirs correlated with epilimnion layer depths and total phoshorus concentrations significantly. On the other hand rotifera variation was affected mainly by physical variables (pH, temperature, dissolved oxygen concentration, conductivity), and crustacean variations were related with total phoshorus. The comperative assessment between limnological variables and zooplankton community in this reservoirs was studied for the first time.

Indices of condition enable the evaluation of the well-being of fish, with the assumption that heavier fish of a given length are in a better condition. Relative weight (W r ) is one of these indices; it is calculated by comparing the actual weight of a specimen with the ideal weight of a specimen in good physiological condition of the same length from the same species, i.e. standard weight (W s ). In this research, length and weight data over the distribution range for Pursak chub Squalius pursakensis, an endemic species distributed in the Sakarya and Porsuk drainages in Northwest Anatolia (Turkey), were used to compute a W s equation by means of the empirical percentile (EmP) method. The W s equation obtained was log 10 W s = -4.657 + 2.614 log 10 TL + 0.127 (log 10 TL) 2 , and the total length range of application was 80-340 mm. Since the EmP W s equation was not influenced by length variation, the use of this equation to compute the relative weight (W r ) for S. pursakensis throughout its area of distribution is suggested.

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In this study, the abundance of rotifera fauna, in the Büyükçekmece Reservoir (İstanbul) and some physicochemical features of the reservoir, were investigated between May 2009 and February 2010. In terms of physicochemical conditions, the trophic state of the reservoir was determined as eutrophic (CTSI= 57.8). A total of 33 rotifera species were identified. Keratella cochlearis represented 40.62% of the total annual rotifera present, and was predominant. It was followed by Polyarthra vulgaris (10.14%), Synchaeta oblonga (9.06%), Brachionus urceolaris (5.58%), Pompholyx sulcata (5.21%) and Epiphanes macroura (%4.86), respectively. The contribution of the other rotifer species to the annual presence of rotifera was determined as being 24.52%. The dominance of these species was attributed to the eutrophic state of the reservoir, because K. cochlearis, P. vulgaris, B. urceolaris and P. sulcata are known as eutrophication indicator species, due to their saprobic valences. Also, the trophic state of the reservoir was found to be eutrophic according to the Q B/T index (= 3). According to the present data about rotifera species, and the abundance of them, the Büyükçekmece Reservoir was specified as eutrophic. However it is necessary to follow the conditions with periodic monitoring to observe the alterations in the Büyükçekmece Reservoir, in this respect the results of the present study would constitute an important baseline for subsequent studies.

Stocking of water bodies with non-native fish species for fisheries enhancement is a common practice worldwide. However, overall limited benefits in terms of revenues for local communities have so far been reported in some countries, whilst accidental introductions of several non-native fish species have occurred. To evaluate the benefits vs. costs associated with common carp Cyprinus carpio stocking practices, a three-year sampling study (2009)(2010)(2011) was carried out across twelve adjacent artificial reservoirs of the Kocaeli Peninsula (north-west Anatolia, Turkey). Apart from common carp, 18 fish species in total were recorded, of which 12 native and six non-native, the latter comprising more than half of the total catch and dominated by gibel carp Carassius gibelio. Even though the abundance of common carp, natives and non-natives increased over the study period, common carp was always comparatively less abundant relative to most of the other species. Overall, the present findings indicate that stocking of common carp into the studied reservoirs has not fully met with the proposed objectives, likely a result of less-than-optimal age-0 fish release strategies and limited availability of spawning grounds. On the other hand, invasion especially by gibel carp is thought to be under way and this may ultimately impact on the abundance of the native fish fauna.Keywords: Richness, abundance, invasion, gibel carp, heuristic significance testing. Kuzey-batı Anadolu'da Bazı Yeni İnşa Edilen Rezervuarlara Yapılan Sazan (Cyprinus carpio) Stoklamaları Yabancı Türlerin Yayılımlarını Arttırabilir ÖzetTürkiye'de çoğunlukla 'yerelleşmiş' sazan Cyprinus carpio stoklamaları ile bilinen su kütlelerinin yabancı tatlısu balıkları ile stoklanmaları dünyada balıkçılığın geliştirilmesi amacıyla gerçekleştirilen yaygın bir uygulamadır. Ancak, aşılamaların yapıldığı su ortamlarına yakın yerleşim yerlerinde yaşayanlara sınırlı katkısı da olsa bu aşılamalar istilacı türlerin dağılımındaki en önemli kaynaklardan biridir. Türkiye'deki su kütlelerine yapılan sazan aşılamalarının getirdiği kar-zarar durumlarını değerlendirmek için Kocaeli Yarımadası'nda (kuzey-batı Anadolu) birbirlerine yakın 12 suni rezervuarda üç senelik (2009-2011) bir araştırma gerçekleştirildi. Sazan haricinde 12'si doğal altısı yabancı olmak üzere toplam 18 balık türü kaydedildi. Yabancı türler toplam elde edilen birey sayısının yarısından fazlasını oluştururken en fazla yakalanan yabancı tür gümüşi havuz balığı Carassius gibelio oldu. Her ne kadar sazan, yerel ve yabancı türler çalışma periyodu boyunca birey sayısı olarak artış gösterse de, sazan diğer türlerin çoğuna nazaran her zaman daha az bollukta elde edilmiştir. Sonuç olarak, sunulan makale rezervuarlara yapılan sazan aşılamalarının uygun olmayan 0 yaş balık aşılama stratejileri ve sınırlı üreme alanları nedeniyle beklenen hedeflere tam olarak ulaşmadığını göstermiştir. Diğer yandan, özellikle gümüşi havuz balığının istilasının devam ettiğini ve bunun sonuçta yerel balık faunasını etkileyeceği düşün...

Son yıllarda dünya çapında artış göstermesine rağmen, sulama amacıyla yapılan su kütlelerinde zooplankton komünitesinin bölgesel ve zamana bağlı değişimleri çok az ilgi görmüştür. Bu çalışmanın amacı, ötrofik bir rezervuarın su kolonunda zooplanktonun dikey dağılımının günlük değişimlerini ortaya çıkarmak ve hangi çevresel ve biyolojik faktörlerin bu dağılımı etkilediğini saptamaktır. Tüm fizikokimyasal ve biyolojik (Klorofil a ve zooplankton türleri) değişkenler genel olarak yüzeyden 4,5-6,0 m derinliğe kadar azalma ve bu noktadan itibaren dikey su kolonunda dibe doğru artış şeklinde benzer bir durum göstermiştir, Copepoda'nın en bol taksa olduğu bunu Cladocera ve Rotifera'nın takip ettiği toplam 15 zooplankton taksonu belirlenmiştir. Rotifera ve Copepod nauplii'nin dağılımı besin tuzları ve klorofil a ile temsil edilen besin konsantrasyonları ile ilişkiliyken, Cyclopoid ve Cladoceranların dikey göçünü etkileyen en etkin faktörler su sıcaklığı, bulanıklık ve askıda yük yoğunluğu olmuştur. Rezervuarda, çalışılan zooplankton komünitesinin bolluğu üzerinde günlük değişimler ve derinlik önemli etkiye sahiptir. Çalışmanın sonucunda farklı çevresel faktörlerde öngörülemeyen değişimlerin, rezervuardaki zooplanktonun dağılımınına olan etkileri ortaya konmuştur.