Papers by Yesim Buyukates
Hydrobiologia, 2004
Common seasonal plankton succession patterns in temperate lakes are well understood, and were des... more Common seasonal plankton succession patterns in temperate lakes are well understood, and were described in the popular PEG-model. Seasonal plankton succession in warm-water lakes, however, is not as well known. Recent theory suggests that some lake systems are characteristic of having alternate system-states, where one of the system-states is characterized by dominance of cyanobacteria, and transition between system-states can be abrupt and undeterminable. Lake Somerville, a shallow, well-mixed, warm-water reservoir located in eastern TX, U.S.A., experiences occasional periods of cyanobacteria dominance. To increase our understanding of seasonal plankton dynamics in warm-water systems, we analyzed 14-years of plankton data spanning a 22-year period. During this period, succession dynamics characteristic of those described by the PEG-model were observed, as well as succession dynamics expected during periods of cyanobacteria dominance, i.e., greater accumulated phytoplankton biovolume, low secondary productivity, and low light penetration. In addition to the PEG-model and cyanobacteria type system-states, other states of the system that were intermediate between these were observed. Therefore, we conclude the lake does not behave according to the alternate system-states model. The change from year to year in early-year cyanobacteria dominance was abrupt and non-monotonic during this period. In addition, the early year performance of cyanobacteria appeared to influence the plankton succession trajectory for the remainder of the season. While the magnitude of lake-flushing early in the year accounted for ∼37% of variability in cyanobacteria prevalence, many of the traditional factors impacting cyanobacteria dominance appeared insignificant.
Notonecta viridis Delcourt ve Alburnus orontis Sauvage Türkiye'nin yerli türleridir. N. viridis'i... more Notonecta viridis Delcourt ve Alburnus orontis Sauvage Türkiye'nin yerli türleridir. N. viridis'in yarı doğal ve doğal ortamda, A. orontis'in ise doğal ortamda sivrisinek larva predatörü olduğu belirlenmiştir. Denemelerde Anopheles sacharovi Favre, Culex pipiens Linnaeus ve Culiseta annulata (Schrank) türlerinin larvaları kullanılmıştır. Yarı doğal koşullarda N. viridis'in günde, 24-28 sivrisinek larvası tükettiği belirlenmiştir. Tercihin Cs. annulata> Cx. pipiens> An. sacharovi şeklinde olduğu anlaşılmıştır. Doğal koşullarda hem N. viridis hem de A. orontis'in bütün sivrisinek larvaları üzerindeki predasyonunun olumlu olduğu anlaşılmıştır. ANAHTAR SÖZCÜKLER: Alburnus orontis, Notonecta viridis, Sivrisinek larvası, Predasyon, Av tercihi
Ekoloji, 2010
... It is known that the system is naturally nitrogen limited (Polat et al. ... Thanks are extend... more ... It is known that the system is naturally nitrogen limited (Polat et al. ... Thanks are extended to İlknur Ak, Sezgin Akarsu, and Gamze Umaz who helped with the field samplings as well as anonymous reviewers for their critiques on a previous iteration of this manuscript. ...
Foodweb interactions, such as competition for limiting resources, are inherently non-linear. Cons... more Foodweb interactions, such as competition for limiting resources, are inherently non-linear. Consequently, they can give rise to chaotic, or undeterminable, population dynamics. Population dynamics are not always undeterminable, however, sometimes they are quite predictable. What conditions cause one behavior to prevail over the other? Here we focus on aquatic environments, specifically plankton ecosystems, and show numerically and experimentally that when
Ekoloji, 2009
Bu çalýþmada Sarýçay Akarsuyu'nda 8 Temmuz-6 Aðustos 2004 tarihleri arasýnda klorofil-a miktarý i... more Bu çalýþmada Sarýçay Akarsuyu'nda 8 Temmuz-6 Aðustos 2004 tarihleri arasýnda klorofil-a miktarý ile sýcaklýk, tuzluluk, pH ve çözünmüþ oksijen (ÇO) gibi çevresel parametreler ve besin elementleri Toplam Azot, Toplam Fosfor, Amonyum Azotu ve Silikat (sýrasý ile TN, TP, NH 4 ve SiO 2 ) arasýndaki iliþkilerin belirlenmesi amaçlanmýþtýr. Örnekleme dönemi boyunca, sýcaklýk deðerleri mevsim normallerinde seyrederken, ÇO ve pH deðerleri periyotlar arasýnda farklýlýk göstermiþ ve sýrasýyla, 1,23-13,1 mg l -1 ile 7,48-9,33 arasýnda kaydedilmiþtir. Klorofil-a konsantrasyonu 0,98-34,45 μg l -1 arasýnda deðiþirken, TP ölçümleri 0,21-0,91 mg l -1 , TN deðerleri 4,78 mg l -1 ile 107,24 mg l -1 , NH 4 konsantrasyonu 0,04-3,68 mg l -1 , SiO 2 0,16 mg l -1 ile 22,4 mg l -1 arasýnda deðiþmiþtir. Klorofil-a ile besin elementleri arasýnda önemli bir korelasyon bulunmamýþtýr. Ancak, çevresel parametrelerden pH (p=0,23), sýcaklýk (p=0,28) ve ÇO (p=0,23) ile klorofil-a arasýndaki korelasyon önemli olarak bulunmuþtur (p<0,01). Çevresel parametrelere ait sonuçlar kirlilik düzeyinin kýsa süreçte düzensiz artmakta olduðunu ve besin elementleri ile klorofil-a arasýnda ters orantýlý anlýk iliþkilerin varlýðýný ortaya koymuþtur. Abstract In this study, it was aimed to examine the relationships among chlorophyll-a, environmental parameters such as temperature, salinity, pH and dissolved oxygen (DO) and nutrients Total Nitrogen, Total Phosphorus, Ammonia-nitrogen and Silicate (TN, TP, NH 4 and SiO 2 , respectively) between 8 July and 6 August, 2004 in Sarýçay Creek. During sampling periods, temperature values followed the usual seasonal values, while DO and pH changed considerably , and ranged between 1,23-13,1 mg l -1 and 7,48-9,33, respectively. Chlorophyll-a concentration changed between 0,98-34,45 μg l -1 , while TP, TN, NH 4 and SiO 2 ranged between 0,21-0,91 mg l -1 , 4,78-107,24 mg l -1 , 0,04-3,68 mg l -1 , 0,16-22,4 mg l -1 , respectively. There was no significant correlation among chlorophyll-a and nutrients. However, there was significant correlation between environmental parameters, such as pH (p=0,23), temperature (p=0,28), DO (p=0,23) and chlorophyll-a (p<0.01). Results of the environmental parameters indicated that the pollution level increased irregularly in a short time and there was on instant reverse relation between inorganic nutrients and chlorophyll-a.
Fundamental Predictability in Multispecies Competition: The Influence of Large Disturbance
The American Naturalist, 2003
Empirical evidence of chaos, or complex behavior, in ecosystems is scarce, presumably due to high... more Empirical evidence of chaos, or complex behavior, in ecosystems is scarce, presumably due to high system-level noise and/or the rarity of conditions necessary for complex behavior to arise. An alternative explanation might be that complex behavior is fragile and readily suppressed by disturbances that are common in many ecosystems. Here we investigated the role of disturbance frequency and magnitude on complex behavior and focused on population succession trajectories in a plankton system. Because of its prominence in aquatic ecology, we used hydraulic flushing and nutrient loading as disturbances. Our findings from numerical modeling exercises and laboratory microcosm experiments using natural plankton assemblages indicated that one aspect of complex behavior, divergence of nearby trajectories, was suppressed when the magnitude and periodicity of hydraulic flushing and nutrient loading were large. In other words, complex succession became determinable. Divergence of nearby trajectories was relatively robust, however, because pulses of not less than 85% of the total inflow were required to suppress this behavior. Our numerical findings also revealed that large hydraulic disturbances could introduce to the system another aspect of complex behavior, aperiodic succession.
Phosphorus Fractions of Various Feedstuffs and Apparent Phosphorus Availability to Channel Catfish
North American Journal of Aquaculture - N AM J AQUACULT, 2000
This study was conducted to determine different phosphorus fractions in corn, cottonseed meal, de... more This study was conducted to determine different phosphorus fractions in corn, cottonseed meal, dehulled soybean meal, fish meal analog, meat-bone meal, fish meal from menhaden Brevoortia spp., rice bran, sorghum, wheat, and wheat middlings, and phosphorus availability of these feedstuffs to channel catfish Ictalurus punctatus. Test diets consisting of a 70:30 mixture of reference diet to test ingredient were used with chromic oxide as the nondigestible marker. The various test diets were fed for 5 d in triplicate to groups of channel catfish weighing approximately 150–200 g, and the fecal samples were obtained by stripping approximately 12 h after feeding. Feed and fecal samples were analyzed for total phosphorus (TP) and soluble reactive phosphorus (SRP), from which apparent availability coefficients were calculated. Apparent availability of SRP exceeded 92% for all ingredients, except menhaden fish meal (61%) and wheat (44%). Total phosphorus availability from animal products was ...
Interannual variability in the seasonal plankton succession of a shallow, warm-water lake
Hydrobiologia, 2000
Hydrobiologia 513: 205218, 2004. © 2004 Kluwer Academic Publishers. Printed in the Netherlands. ... more Hydrobiologia 513: 205218, 2004. © 2004 Kluwer Academic Publishers. Printed in the Netherlands. ... Interannual variability in the seasonal plankton succession of a shallow, warm-water lake ... Daniel Roelke, Yesim Buyukates, Mike Williams & Jason Jean Texas ...
Hydrobiologia, 2005
... Key words: pulsed inflow, zooplankton, phytoplankton, diversity, biomass, microcosm, estuary,... more ... Key words: pulsed inflow, zooplankton, phytoplankton, diversity, biomass, microcosm, estuary, wastewater discharge ... studies that focused on N and P loading into the Nueces River Estuary from a ... in treatments receiving pulsed inflows, but the mode of inflow did not influence ...
The Diversity of Harmful Algal Bloom-Triggering Mechanisms and the Complexity of Bloom Initiation
Human and Ecological Risk Assessment, 2001
Mechanisms influencing initiation of harmful algal blooms (HABs) are diverse, and are not likely ... more Mechanisms influencing initiation of harmful algal blooms (HABs) are diverse, and are not likely to be mutually exclusive. Rather, initiation of HABs is a result of interactions between processes, which result in biological, physical, and chemical conditions optimal for a bloom. Due to the complexity of some bloom initiation processes, bloom-preventative management may be possible. Results from a modeling exercise
Cladocerans of an urbanized harbour: effects of environmental parameters on vertical distribution, occurrence, abundance, and seasonal variation
Crustaceana, 2009
Chemistry and Ecology, 2012
The adsorption of copper, zinc, cobalt, lead and cadmium ions onto Colpomenia sinuosa was studied... more The adsorption of copper, zinc, cobalt, lead and cadmium ions onto Colpomenia sinuosa was studied as a function of contact time, initial metal ion concentration and initial pH. In addition, desorption studies were performed. Characterisation of this adsorbent was also confirmed by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) analysis. Batch adsorption experimental data were analysed using Langmuir, Freundlich and Dubinin-Raduschkevich (D-R) adsorption isotherms. The results indicated that the biosorption equilibrium was well described by both the Freudlich and D-R isotherms. Moreover, sorption kinetics was performed and it was observed that equilibrium was reached in <60 min, which could be described by the pseudo-second-order kinetic model for all heavy metals. The sorption of heavy metals onto the biomass was largely dependent on the initial solution pH. The elution efficiency for heavy metal ions desorption from C. sinuosa was determined for 0.1 M HCl, 1.0 M HCl and 1.0 M HNO 3 . Desorption efficiency and also adsorption capacity were highest for Pb(II). The results indicate that C. sinuosa has great potential for the removal of heavy metals in an ecofriendly process.
Limnology and Oceanography, 2002
Many of the processes that influence initiation and development of harmful algal blooms (HABs) in... more Many of the processes that influence initiation and development of harmful algal blooms (HABs) in lake eco- systems also affect the nature of phytoplankton population overturn—here referred to as the dynamics of succes- sion—and species diversity. Consequently, the dynamics of succession and species diversity might reflect the lake's resistance to HABs. We explored this idea by developing a potential system-level
Uploads
Papers by Yesim Buyukates