Tolerance, optimum ranges, and ecological requirements of freshwater Ostracoda (Crustacea) in Lake Aladağ (Bolu, Turkey)

During monthly sampling from Lake Alada (Bolu, Turkey) between April 2003 and June 2004, nine ostracod taxa (Candona candida, Cypridopsis vidua, Darwinula stevensoni, Eucypris virens, Eucypris sp., Heterocypris sp., Limnocythere inopinata, Physocypria kraepelini, and Tonnacypris lutaria) were recorded from seven stations. Physocypria kraepelini was commonly found in the lake while the others were recorded in particular months. UPGMA analyses clustered three groups based on their occurrence. Accordingly, the occurrence of species (C. candida, E. virens, and T. lutaria) was positive and significantly related to each other. Two species, P. kraepelini and D. stevensoni, showed a significant positive relationship with electrical conductivity. A significant negative correlation was found between the occurrence of P. kraepelini and dissolved oxygen, while there was a significant positive correlation between the occurrence of P. kraepelini and turbidity. About 76% of the relationship between species and environmental factors was explained by the first two axes of canonical correspondence analyses (CCA). Temperature and dissolved oxygen were the two most important influences on the species assemblages. All species showed different but high optima and tolerance ranges, corresponding with their cosmopolitan characteristics. These responses may be related to unstable ecological characteristics of Lake Alada, which is often subjected to human activity.     

Ecological requirements of Ostracoda (Crustacea) in a heavily polluted shallow lake,Lake Yeniçağa (Bolu,Turkey)

Although the area of Lake Yeniça?a is a potential candidate for RAMSAR convention, several anthropogenic factors compromise its biological diversity. This is mostly due to nutrient-rich water released from both point and nonpoint sources. Thirteen ostracod taxa (Candona neglecta, C. candida, Ilyocypris bradyi, Darwinula stevensoni, Cypridopsis vidua, Physocypria kraepelini, Cypria ophtalmica, Prionocypris zenkeri, Eucypris virens, Herpetocypris reptans, Pseudocandona compressa, Fabaeformiscandona fabaeformis Potamocypris cf. fulva) were found during this study. Potamocypris cf. fulva is a new record for the Turkish freshwater ostracod fauna. The first nine of these species have broad geographic ranges, implying high tolerance levels to different environmental variables. Based on the estimated species optima and tolerance levels, two species exhibited higher effective number of occurrences (C. neglecta, and D. stevensoni, respectively) than the other species. Three species (C. neglecta, D. stevensoni, I. bradyi) did not show significant correlation with any environmental variable we used. Both Canonical correspondence (CCA) and Pearson correlation analyses showed that temperature was the most effective predictor of species occurrence, followed by electrical conductivity and redox potential. In contrast, pH and dissolved oxygen of water were the least effective predictors. Approximately 71% of the correlation between community composition and environmental variables was explained by the first axis of the CCA diagram, which had a relatively low (7.7%) cumulative variance of species. The lower (560 μg/l) and the upper (2030 μg/l) levels of ammonia (NH₃) exceeded the limits during winter season. The concentrations of total coliform and Escherichia coli bacteria were measured up to 10 × 10⁷ cfu/ml and 10 × 10³ cfu/ml, respectively. Results of physicochemical measurements, microbiological counts, and species data indicate that water quality of Lake Yeniça?a has been rapidly deteriorated by anthropogenic factors that are the main threat for not only the lake’s aquatic diversity but also human health around the lake.     

Predator-Mediated Coexistence of Exotic and Native Crustaceans in a Freshwater Lake?

The predatory effects of a Dipteran insect, Chaoborus, on the competition between exotic cladoceran Daphnia lumholtzi and two natives, D. catawba and D. pulex, were studied for a period of three years in a freshwater reservoir, Lake James, North Carolina (USA). D. lumholtzi was first encountered in September 1997 and it was present only between August and October when population densities of native species were low and that of Chaoborus sp. was high. The patterns observed in the population dynamics of the exotic D. lumholtzi and two natives, Chaoborus suggest that a predator mediated coexistence phenomenon might be taking place in Lake James. The strong positive correlation between Chaoborus and D. lumholtzi and the negative correlation between Chaoborus, D. catawba and D. pulex is supportive of this hypothesis.     

Early Miocene rodents of Gökler (Kazan Basin,Central Anatolia,Turkey)

Abstract

The rich and relatively diverse fossil mammalian assemblage from Gökler is of special importance for understanding of faunal evolution in Central Anatolia. Large mammals were not recovered, but insectivores and rodents are abundant. The assemblage of rodents is studied in detail and comprises mainly diversified cricetids. Dormice are abundant, but are represented by only one species. Squirrels are represented only by few specimens and also beaver remains were identified. Spanocricetodon sinuosus is referred to a new genus Latocricetodon nov. gen that is tentatively assigned to the Pseudocricetodontinae. Newly named species are Cricetodon goklerensis sp. nov., Democricetodon haltmari sp. nov., Eumyarion lukasi sp. nov. and Glirudinus matusi sp. nov. The rodent assemblage is assigned to local zone C which is correlated to the European biounit MN2 (early Miocene). Our biochronological assessment is supported by radiometric dating from two volcanic ash layers.

Latocricetodon

LSID http://zoobank.org/urn:lsid:zoobank.org:act:3414DB1E-0C5E-4154-BE5E-02A9ED183B1A

Cricetodon goklerensis

LSID http://zoobank.org/urn:lsid:zoobank.org:act:1B658872-6C10-4355-B87C-3E6277AF4EDA

Democricetodon haltmari

LSID http://zoobank.org/urn:lsid:zoobank.org:act:9B13F956-7F8C-406A-9970-1F5E999E54C6

Eumyarion lukasi

LSID http://zoobank.org/urn:lsid:zoobank.org:act:34DED87E-855F-4969-AB84-10BED5C572BF

Glirudinus matusi

LSID http://zoobank.org/urn:lsid:zoobank.org:act:798ECB9A-E3B5-4C38-B5B3-FEB17AF734FE     

Origin and production of phosphatases in the acid Lake Gårdsjön

The activity of acid phosphatases was followed for one year in Lake Gårdsjön as well as in the inlet and the outlet of the lake. A budget of the phosphatases was calculated, including an estimation of the production of phosphatases. The phosphatase activity was also measured in two basins upstream of L. Gårdsjön: the north basin and the south basin of L. Stora Hästevatten.The acid phosphatase activity was very high compared with reported alkaline phosphatase activities in other lakes. About 95% of the phosphatases in L. Gårdsjön was produced in the lake, and the production was highest in early summer.Small Chrysophyceae (< 10 µm) probably produced the majority of the acid phosphatases in the investigated lakes, and accordingly could be favoured in environments with low phosphorus supply due to their ability to produce large amounts of phosphatases.     

Ostracods and the Holocene palaeolimnology of Lake Qarun, with special reference to past human–environment interactions in the Faiyum (Egypt)

We present an ostracod record covering the past two millennia from an 8.25-m core taken from Lake Qarun, in the Faiyum Depression of Egypt. The occurrence of ostracod species in the lake is controlled primarily by variations in solute composition, which are in turn related to shifts in catchment land use. At times when the Faiyum Depression supported thriving agriculture, lake water contained Na⁺–Cl^? brine, and Cyprideis torosa dominated the ostracod assemblage. When the Faiyum Depression experienced periods of environmental and economic decline, lake water contained Na⁺–HCO₃ ^? brine, and Limnocythere inopinata dominated. The relative abundance of other ostracod species provides additional information about past conditions in Lake Qarun including salinity and lake level changes. Overall, the ostracod assemblages provide evidence for human influences in the Faiyum, which extend back before instrumental or detailed observational records began.     

Archaeal Microbial Diversity of Hypersaline Lake Acıgöl,Denizli, Turkey

Archaeal diversity in Lake Ac?göl, a closed-basin, alkaline, hypersaline lake located at the northern edge of western Tourides in southwest Anatolia, was investigated using culture-independent methods. Microbial mat samples were collected from six different points. Archaeal 16S rRNA gene libraries were generated using domain specific oligonucleotide primers, and 16S rRNA gene sequences of clone libraries were analyzed phylogenetically. Denaturing gradient gel electrophoresis of 16S rRNA genes showed a variance in diversity with spatial differences. Archaeal diversity of Ac?göl is dominated by the members of family Halobacteriaceae which requires both high salt concentration and high pH for growth. Sequence analysis of archaeal 16s rRNA genes indicates the presence of the phylotypes affiliated with the genera Halorubrum, Halosimplex, Halorhabdus, Haloterrigena and Natronococcus in the analyzed samples.     

The gametogenic cycle of Leguminaia whaetleyi (Lea, 1862) in lake Gölbaşı, Turkey (Bivalvia: Unionidae)

The gonadal structure and cycle of the Leguminaia whaetleyi is described for the first time indicating that 5% of this species is simultaneous hermaphrodite. A total of 420 individuals were collected in monthly samples from October 2008 to September 2009 in G?lba?? Lake, Turkey. Calculation of the condition index and histological examination of the gonads showed that gametogenesis began in January. Spawning occurred between May and August with one maximum peak in July. Annual maximum oocytes size peaked in July. The population consisted of simultaneous hermaphrodite individuals. Sex ratio of L. whaetleyi was significantly different from the expected 1:1 ratio (P< 0.05), and also female biased sex ratio was recorded. In hermaphrodite specimens, male and female follicles were mixed in the visceral mass but can be clearly distinguished by light microscopy study. L. whaetleyi appears to be a dioecious species in which 25 specimens were simultaneous hermaphrodite and under certain environmental conditions may be capable of self-fertilization. This suggests that detailed studies on sex ratio of L. whaetleyi may be helpful in understanding unionid phylogeny.     

Ecology of purple sulfur bacteria in the highly stratified meromictic Lake Shunet (Siberia, Khakassia) in 2002–2009

Phototrophic sulfur bacteria form dense accumulations in the chemocline zones of stratified lakes where light reaches the sulfide-containing layers of water. Many works are dedicated to the ecophysiology of these microorganisms in meromictic lakes. However, the role of these microorganisms in the trophic network of these ecosystems, the ways of biomass utilization, and the contribution to the turnover of biogenic elements have so far been insufficiently understood. This work deals with the analysis of many years?? seasonal dynamics of the biomass of purple sulfur bacteria and the physicochemical conditions of their environment in Lake Shunet (Siberia, Khakassia, Russia), unraveling the causes of their anomalous development in the chemocline of this lake, as well as the comparative analysis of such type of ecosystems. Lake Shunet is characterized by markedly pronounced stratification and the high density of purple sulfur bacteria (PSB) in the chemocline, which is comparable to that of Lake Mahoney (Canada) where the number of PSB is the greatest among those known in the world. It was shown that, in the period 2002?C2009, the total amount of bacterio-chlorophyll a in the water column of Lake Shunet increased and did not correlate with the seasonal variations in temperature and illumination in the chemocline. It was established that PSB cells in the purple layer experienced the effect of self-shading. The sedimentation rate of purple sulfur bacteria in Lake Shunet was low due to the pronounced density gradient in the chemocline zone. Thus, the high number of PSB in the chemocline was due to the combination of strong illumination, a high sulfide concentration, and a high water density gradient, which was responsible for stable stratification and contributed to the accumulation of the cells in a narrow layer. The data obtained could be useful for the paleoreconstruction of climatically deter-mined changes in the level of the lake and its periods of meromixis by the presence of carotenoids and bacte-riochlorophylls in the bottom sediments.     

Occurrence,succession and distribution of chroöcoccal Cyanobacteria in Lake Maarsseveen I

Four species of chroöcoccal Cyanobacteria were dominant in Lake Maarsseveen I in 1987:Gomphosphaeria lacustris, Chroöcoccus sp.,Aphanocapsa sp. andMicrocystis aeruginosa. The first two were dominant in the water column, the latter two in the sediment. In the water columnAphanocapsa, Microcystis andGomphosphaeria appeared and showed highest abundance at the same time, whileChroöcoccus filled the gaps between the peaks of the others. The distribution in the sediment was related to its texture.     

Pollution,source, and ecological risk assessment of trace elements in surface sediments of Lake Aktaş, NE Turkey

This study applies ecological indices to determine the anthropogenic-based metal enrichment and potential ecological and ecotoxicological risks posed by each metal in the sediments of Lake Akta?, NE Turkey. Sediment samples were collected from nine stations (St1–St9) within the Turkish boundary of Lake Akta? and the heavy metal, total organic carbon %, CaCO₃%, chlorophyll degradation products (chlorophyll-α), total sulfur %, and total phosphate % contents in the sediment samples were determined. Enrichment factor (EF), pollution load and potential ecological risk (PER) indices were calculated to shed light on the ecological effects of heavy metals. The metal content was ranked in descending order of Al > Fe > Mn > Zn > Ni > Cr > Cu > Pb > As > Cd > Hg. The EF values ranged 0.87–1.0 for Cu, 1.04–1.14 for Pb, 1–1.08 for Zn, 0.88–0.95 for Ni, 0.99–1.24 for Mn, 0.89–0.93 for Fe, 0.82–1.01 for As, 0.96–1.19 for Cd, 0.94–1.0 for Cr, and 1.42–1.90 for Hg. Minimal contamination was found for Hg. Pollution load, PER, and toxic risk indices indicated no ecological risk currently. However, considering the PER index for metals individually, a moderate potential risk was detected for Hg. The data obtained from multivariate statistical analyses indicate that Hg and Mn originate from the atmosphere, while other elements have lithogenic sources.     

Airborne Pollen Grains of Bozüyük (Bilecik, Turkey)

Airborne pollen grains in the atmosphere of Bozüyük were investigated over a 2 yr period from 2000 to 2001 using a Durham sampler. A total number of pollen grains of 5 170 pollen grains belonging to 32taxa were identified and recorded along with some unidentified pollen grains. Of all the pollen grains, 78.66%were arboreal, 19.20% were non-arboreal, and 2.12% were unidentified. The majority of pollen grains investigated were Pinus, Platanus, Quercus, Cupressaceae, Poaceae, Fagus, Salix, Rosaceae, Urticaceae,Asteraceae, and Chenopodiaceae. The maximum number of pollen grains was recorded in May.     

Phosphorus in acidified lakes: The example of Lake Gårdsjön,Sweden

Supply and turnover of phosphorus was studied in an acidified lake ecosystem, Lake Gårdsjön, located in southwestern Sweden. This study included transport and budget calculations combined with field and laboratory experimental work on abiotic phosphorus chemistry and biological utilization of phosphorus. The main conclusions presented in this paper are:

- The acidification process in inland waters resulting from acid atmospheric deposition is accompanied by ‘oligotrophication’ because of reduced input of phosphorus from the drainage area, possibly due to efficient fixation of phosphorus to aluminium complexes in the B-horizon of podzol soils

- Primary productivity in acidified lakes is limited mainly by low phosphorus supply

- Algal utilization of phosphorus in acidified lakes is impaired, yielding lower biomass than could be expected from ambient phosphorus concentrations. One possible reason for this could be that enzymatic recycling of organic phosphates is prevented by high levels of aluminium in lake water.

     

Impact of nest relocation on the reproductive success of Loggerhead Turtles,Caretta caretta,in the Göksu Delta,Turkey (Reptilia: Cheloniidae)

When the nests of marine turtles are at a risk of inundation, relocation of the nests are often used in the conservation measures. Here, I determined the effect of nest relocation on Loggerhead Turtle (Caretta caretta) egg hatching success during the 2013 and 2014 nesting seasons in the Göksu Delta, Mersin, Turkey. I compared natural and relocated clutches, including those relocated before and after inundation, and evaluated 102 (94.6%) and 63 (81.1%) of survived nests in 2013 and 2014 respectively. Relocated nests experienced a 30% decrease in hatching success and a more prolonged incubation period compared to nests left in situ. Egg failure in nests relocated before and after inundation was similar in early-stage embryos, whereas it was three-fold higher in mid-stage embryos and two-fold lower in late-stage embryos. Thus, there was no significant difference in overall hatching success between the two relocation types. Moreover, there was no effect of delayed relocation of nests after inundation on hatching success. Possible impacts specific to the nesting site should be considered and explored before using nest relocation as a conservation tool. The relocation approach is recommended for nests at a high risk of inundation when the loss of nests is inevitable.     

Reproducing Authigenic Carbonate Precipitation in the Hypersaline Lake Acıgöl (Turkey) with Microbial Cultures

In the present study, laboratory precipitation experiments using similar water chemistry and two different bacterial cultures from Lake Ac?göl sediments, a hypersaline lake in Turkey, were performed to reproduce mineral assemblages similar to those found in the lake. Two different bacterial cultures induce various calcium/magnesium carbonates precipitation under all the experimental conditions (solid vs. liquid): Hydromagnesite, dypingite, huntite, monohydrocalcite, and aragonite. The geochemical program PHREEQC was used to calculate the mineral saturation indexes in the cultures and in lake water. Carbonate mineral assemblages identified in the experiments seem to be independent of the type of microorganisms but rather controlled by the chemical composition and physical conditions of the media. The relative amounts of monohydrocalcite, hydromagnesite, and dypingite are controlled by varying sulfate concentration from 0 to 56 mM. This demonstrates a kinetic effect that could similarly affect the mineral assemblage in the lake. Also the spherical morphology of hydromagnesite points to growth of these minerals under partial inhibition in the brine under high concentrations of ions and organic polymers produced by the microbial communities. As reproduced by the culture experiments, the authigenic carbonate mineral assemblage of Lake Ac?göl most likely results from interplay of ionic composition of the brine and microbial effects.     

Qualitative and quantitative structure,diversity and fluctuations in abundance of zooplankton in Lake Xolotlán (Managua)

The qualitative and quantitative structure of the zooplankton community was studied in 11 localities of Lake Xolotlan (Managua). Twelve rotifers, 4 cladoceran and 5 copepods species were identified. Community diversity (Shannon-Wienerindex) is low,viz. 0,83–2.20. At all times, copepods were the most abundant group. Rotifer densities were higher in zones influenced by rivers and organic pollution. Cladocerans were permanently present in low densities. Climatic events (rainfalls and dry periods) determined population fluctuations of the main zooplankton groups.     

Palaeoecology of Upper Pleistocene-Holocene bryozoan and foraminiferal assemblages from Ku?dili (Kadiköy, Istanbul, Turkey)

Bryozoan and foraminiferal assemblages from a core drilled in the Kusdili (Kadiköy, Istanbul) Upper Pleistocene-Holocene sequence were studied. Assemblages are absent from the very basal and top parts but they are well represented all along the middle part of the sequence. All the species found presently live in the Mediterranean. In the area sedimentation seemingly started about 13?000 years ago in very shallow near-shore environments with the deposition of pebbly sediments rapidly evolving to mud. Near the base, the presence of erosional surface allows to recognize three successive sedimentary cycles. Bryozoan and foraminiferal assemblages found in the middle part of the sequence testify to a shallow water, estuarine or lagoonal paleo-environment, in which effects of low salinity waters, more obvious toward the top, could be related to the reestablishment of a connection between the Marmara Sea and the Black Sea through the Bosphorus, about 7000 years BP.     

Long-term Patterns of Shifts between Clear and Turbid States in Lake Krankesjön and Lake Tåkern

During the past century, Lake Tåkern and Lake Krankesjön, southern Sweden, have shifted repeatedly between a state of clear water and abundant submerged vegetation, and a state of turbid water and sparse vegetation. Long-term empirical data on such apparently alternative stable state dynamics are valuable as complements to modeling and experiments, although the causal mechanisms behind shifts are often difficult to identify in hindsight. Here, we summarize previous studies and discuss possible mechanisms behind the shifts. The most detailed information comes from monitoring of two recent shifts, one in each lake. In the 1980s, L. Krankesjön shifted to clear water following an expansion of sago pondweed, Potamogeton pectinatus. Water clarity increased when the pondweed was replaced by characeans. Zooplankton biomass in summer declined and the concentration of total phosphorus (TP) was reduced to half the previous level. The fish community changed over several years, including an increasing recruitment of piscivorous perch (Perca fluviatilis). An opposite directed shift to turbid water occurred in Lake Tåkern in 1995, when biomass of phytoplankton increased in spring, at the expense of submerged vegetation. Consistent with the findings in L. Krankesjön, phyto- and zooplankton biomass increased and the average concentration of TP doubled. After the shift to clear water in L. Krankesjön, TP concentration has increased during the latest decade, supporting the idea that accumulation of nutrients may lead to a long-term destabilization of the clear water state. In L. Tåkern, data on TP are inconclusive, but organic nitrogen concentrations oscillated during a 25-year period of clear water. These observations indicate that intrinsic processes cause gradual or periodic changes in system stability, although we cannot exclude the possibility that external forces are also involved. During such phases of destabilization of the clear water state, even small disturbances could possibly trigger a shift, which may explain why causes behind shifts are hard to identify even when they occur during periods of extensive monitoring.     

Potential Distribution Modeling and Morphology of Pelias barani(B?hme and Joger, 1983) in Turkey

The climatic preferences of Pelias barani, a rare Pontic endemic viper, are analysed and a new locality record is reported. According to species distribution modeling, with the average test AUC was was 0.904 ± 0.068, bioclimatic variables such as Precipitation of driest month(45.5%), Temperature seasonality(18.9%), Precipitation seasonality(17.9%) and Maximum temperature of warmest period(14.7%) appear to have the most useful information on geographic distribution of Pelias barani. Distribution models of Pelias barani under current climatic conditions showed better adaptation to the northwest and northeast part of Turkey.