Microsatellite mapping of genes for semi-dwarfism and branched spike in Triticum durum Desf. var. ramosoobscurum Jakubz. “Vetvistokoloskaya”

A combination of increased harvest index and increased seed number per plant may improve wheat yield. We found an accession Triticum durum Desf. var. ramosoobscurum Jakubz. “Vetvistokoloskaya” R-107, whose plant height was short and spike was branched. To characterize R-107, we mapped the genes for semi-dwarfism and branched spike. Semi-dwarf gene Rht_R107 (Reduced height R107) from R-107 was allelic to Rht11 and Rht-B1b on chromosome 4BS. Rht_R107, as well as Rht11, was recessive and insensitive to gibberellic acid. Microsatellite mapping indicated that Rht_R107 was linked to Xwmc48 (1.2?cM) on chromosome 4BS, and Rht11 was also linked to Xgwm495 marker (19.4?cM) on chromosome 4BS. The locus responsible for branched spike in R-107 was mapped by genotyping three F₂ populations using microsatellite markers. Phenotypic analysis revealed that branched spike was under control of a recessive allele at a single locus. The bh (branched head) locus was located on chromosome 2AS and the marker Xgwm425 flanked the bh gene proximally.     

Soil protection strategies in Brandenburg —Management of waste recycling on devastated areas subject to recultivation (soil protection in recultivation areas)

The article reflects on considerations in theLand(Federal State) Brandenburg in the preliminary stages of aLand regulation on the recycling of wastes on devastated areas from the viewpoint of soil protection. Within the framework of a proposed recultivation, the benefit and harmlessness of recycling shall be examined. The benefits are derived from the preservation, improvement and restoration of soil functions without detrimental effects on other soil functions. In order to make full use of the benefits, a graduated, site-specific system for the main nutrients is presented. For pollutants, different approaches for limitation of the input are discussed.     

Study of the specific and varietal diversity of field crops in Bulgaria

1. The particular geographical situation of Bulgaria, its natural connection between Asia and Europe, the various landscapes, the diverse soil and climatical conditions have been and are favourable conditions for the development of a diverse vegetation.
2. The flora of the country consists of more than 5000 species; among them 19 species, 35 subspecies, 115 varieties and 60 forms have been newly described in recent times.
3. With a large specific and varietal diversity the group of field crops is represented by wheat, barley, oat, rye, chickpea,Lathyrus, lucerne, clover, rose and tlax.
4. As a result of the systematic study of 22 species of field crops the following taxa have been described as new ones: Triticum pseudopolonicum Pop. (Popov 1949/50);Tr. boeoticum Boiss. var.bulgaricum Stranski;Tr. monococcum L. var.sofianum Stranski (Stranski 1929) Secale anatolicum Boiss. var.rhodopeum (Delip.) Gan.;S. montanum Guss. var.balcanum Gan. (Jordanov 1963) Cicer arietinum L. var.afghanico-aurantiacum Koin., var.turcico-aurantiacum Koin., var.bohemico-atrum Koin. and var.hispanico-aurantiacum Koin. (Kojnov 1968) Lens esculenta Moench var.roseum Staik. and var.rubrum Staik. (Stajkov 1963) Trifolium incarnatum L. ssp.incarnatum var.intermedium Ko?. and var.minor Ko?.;Tr. pratense L. var.stojanovii Ko?. and var.stmnskii Stoj. etStef. f.velenowskyana Ko?.,Tr. alexandrinum L. var.madarensae Ko?. (Jordanov 1976).
5. The rich specific and varietal diversity of field crops gives the opportunity of carrying out an intensive and successful breeding work.

     

A haplotype specific to North European wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

A previous study indicated decreased DNA content of chromosome 4A in the wheat (Triticum aestivum L. cv. Tähti) compared to cvs. Chinese Spring and Rennan. Here we show that the lower 4A DNA content is associated with a specific haplotype in the distal part of 4AL. In 41 cultivars of bread wheat (T. aestivum L.), including cv. Tähti, a common haplotype was identified in the linkage disequilibrium region on the long arm of chromosome 4A (4AL). The haplotype (haplotype A) is characterized by 7 SSR and 5 EST marker alleles, including five zero-alleles. Haplotype A was found in 46 % of the Swedish/Finnish/Estonian spring wheat genotypes, while only one of the modern wheat accessions from Germany carried the same haplotype. Fluorescent cytometry analysis linked haplotype A to diminished DNA content of chromosome 4A. The haplotype was introduced into the Canadian and US breeding programs at the beginning of the twentieth century (cvs. Marquis, Thatcher, Ruby) from the common progenitor, the Polish landrace Fife, and it is still found in modern wheat germplasm in these countries. Zero-alleles characteristic for haplotype A were also detected in several accessions of European spelt (Triticum spelta L.), and in two accessions of tetraploid Triticum timopheevii Zhuk. The presence of haplotype A in European spelt indicates the considerable antiquity of the haplotype, as it must have been inherited from the hexaploid or tetraploid parent of spelt in at least one hybridization event.     

Simulation of nutrition of forests under stress using forgyte-11

Forest ecosystems are being subjected to an increasing variety of stresses for which we do not yet have rotation-length experience. Where we lack such experience, we cannot make experience-based predictions of the long-term effects of these stresses. While we are accumulating such experience, computer models can be used to make interim knowledge-based predictions. Most scientific knowledge has been produced by reductionist; disciplinary, process-based research. Such knowledge is a vital component of any explanation of natural or human-induced landscape phenomena, but cannot, in its reductionist, disciplinary form, provide an adequate basis on its own for long-term predictions about these phenomena. Such predictions require the development of computer models of ecosystem form and function based on the integration of knowledge from eco-physiology, autecology, community ecology, soil science, and climatology into ecosystem-level models that accurately describe the function and temporal dynamics of forest ecosystems.The ability of the ecosystem-level forest management simulation model FORCYTE-11 (FORest nutrient Cycling and Yield Trend Evaluator) to simulate forest stresses is described briefly. The question of how to model other stresses, such as air pollution, acid rain, climate change, soil compaction and erosion, and moisture competition is discussed, and the outline of a new model (FORECAST: FORestry and Environmental Change ASsessmenT) is presented.     

Mercury in plants,soil and atmosphere near a chlor-alkali complex

Data of atmospheric Hg concentrations measured near the chlor-alkali complex of Rosignano Solvay (Livorno, Italy) show that the impact of the industry on the terrestrial environment is restricted to a close area around; background values (3 to 5 ng m^?3) are reached within a radius of 4 to 5 km. Hg levels in plants (Poa sp. Pinus nigra and Solidago sp.) and in soil show the highest values in the sampling stations near the electrolytic cells.     

Cu(II) Biosorption and Competitive Studies in Multi-ions Aqueous Systems by Arthrobacter sp. Sphe3 and Bacillus sphaericus Cells: Equillibrium and Thermodynamic Studies

Arthrobacter sp. Sphe3 and Bacillus sphaericus cells were used for Cu(II) biosorption. The effect of contact time, biosorbent dose, equilibrium pH, temperature and the presence of other ions on the efficiency of the process were extensively studied. Optimum pH value and biomass concentration were determined at 5.0 and 1.0?g/l, whereas contact time was found to be 5 and 10?min for Arthrobacter sp. Sphe3 and Bacillus sphaericus biomass, respectively. Equilibrium data fitted very well to Freundlich model (R ²?=?0.996, n?=?2.325, K _f?=?8.141) using Arthrobacter sp. Sphe3. In the case of B. sphaericus, a Langmuir adsorption model [R ²?=?0.996, Q _max?=?51.54?mg-Cu(II)/g] showed to better describe the results. Potentiometric titration and Fourier transform infrared (FTIR) spectroscopy showed that amine, carboxyl and phosphate groups participate in Cu(II)-binding. The calculated thermodynamic parameters indicated the spontaneous and feasible nature of Cu(II) biosorption on both biosorbents. Selectivity of Cu(II) biosorption was examined in binary and multi-ions systems with various anions and cations which are commonly found in municipal and industrial wastewater. A specificity towards Cu(II) was observed in binary mixtures with Cl^-, CO ₃ ^-2 , NO ₃ ^- , SO ₄ ^-2 , PO ₄ ^-3 , Mg⁺² and Ca⁺², and As(V) with the maximum uptake capacity remaining constant even at high competitive ion??s concentrations of 200?mg/l. Desorption studies showed that Cu(II) could be completely desorbed from Cu(II)-loaded Arthrobacter strain Sphe3 and B. sphaericus biomass using 1.0 and 0.8?M HCl, respectively, and both bacterial species could be effectively reused up to five cycles, making their application in wastewater detoxification more attractive.     

Simulation of nutrition of forests under stress using FORCYTE-11

Forest ecosystems are being subjected to an increasing variety of stresses for which we do not yet have rotation-length experience. Where we lack such experience, we cannot make experience-based predictions of the long-term effects of these stresses. While we are accumulating such experience, computer models can be used to make interim knowledge-based predictions. Most scientific knowledge has been produced by reductionist, disciplinary, process-based research. Such knowledge is a vital component of any explanation of natural or human-induced landscape phenomena, but cannot, in its reductionist, disciplinary form, provide an adequate basis on its own for long-term predictions about these phenomena. Such predictions require the development of computer models of ecosystem form and function based on the integration of knowledge from eco-physiology, autecology, community ecology, soil science, and climatology into ecosystem-level models that accurately describe the function and temporal dynamics of forest ecosystems. The ability of the ecosystem-level forest management simulation model FORCYTE-11 (FORest nutrientCycling andYieldTrendEvaluator) to simulate forest stresses is described briefly. The question of how to model other stresses, such as air pollution, acid rain, climate change, soil compaction and erosion, and moisture competition is discussed, and the outline of a new model (FORECAST:FORestry andEnvironmentalChangeASsessmenT) is presented.     

Foliar sensitivity of eight eastern hardwood tree species to ozone

As part of a larger 3-yr study, container-grown seedlings of black cherry (Prunus serotina) red maple (Acer rubrum), red oak (Ouercus rubra), sweetgum (Liquidambar styraciflua), white ash (Fraxinus americana), white oak (Ouercus alba), yellow-poplar (Liriodendron tulipifera), and yellow birch (Betula allegheniensis) were exposed to 0,0.075, or 0.15 μL L-¹ O₃ in laboratory controlled-environment chambers for 6 hr d^?1 on 2 consecutive days for 12 weeks. On the third consecutive day of each week, plants were treated for 45 min with precipitation at pH 3.0 or 4.2. The only significant foliar symptoms were induced by the O₃ treatments, and the severity of symptoms was not influenced by precipitation pH. The most common symptom was a dark, adaxial stipple which was most severe on the oldest leaves. Equations were developed to express the influence of leaf position on percent leaf injury following 4, 8, and 12 weeks of treatment. Based on percent leaf tissue showing stipple and defoliation following exposure to 0.15 μL L^?1 O₃, the most sensitive species to O₃ was black cherry, followed by sweetgum, yellow-poplar, white ash, red maple and yellow birch. Red oak and white oak foliage did not exhibit stipple.     

Agricultural Impacts on Lake and Stream Water Quality in Grand Lake St. Marys, Western Ohio

Agricultural activities release variable products into air, soil and water ecosystems. The study was conducted to evaluate the impact of agriculture and concentrated livestock operations on stream and lake water quality in Grand Lake St. Marys watershed of north-western Ohio. Temporal water samples from the lake and the 6 feeding streams were collected bimonthly from January 2005 to May 2007, processed and measured for temperature, turbidity, pH, electrical conductivity (E _C), ammonium $\left( {{\text{NH}}_{\text{4}}^{\text{ + }} } \right)$ , nitrate $\left( {{\text{NO}}_{\text{3}}^ - } \right)$ , dissolved phosphorus (P), ultra-violet (UV) light absorption, and dissolved oxygen (DO), employing standard methods of analysis. The measured data were normalized and integrated into a simple index (WQ_Index) to evaluate overall water quality. Results showed that over 90% of the area in the watershed was under cropland with associated livestock operations. With a land area equal to 195 km² represented by the six major tributaries, the average animal density was over 240 units km^?2. As a result, land disposal of manure from confined feedings operations and direct deposit by grazing animals contributed to non-point sources of water pollution. While $\left( {{\text{NH}}_{\text{4}}^{\text{ + }} } \right)$ and P concentration, turbidity, and UV absorption peaked during the summer, the $\left( {{\text{NO}}_{\text{3}}^ - } \right)$ and DO concentration in both stream and lake water was lowest in the summer. Water sampled from the Coldwater, Beaver and Prairie creeks had higher turbidity, $\left( {{\text{NH}}_{\text{4}}^{\text{ + }} } \right)$ , and P than other creeks. However, DO concentration and UV absorption of water did not change significantly by the influence of streams. The WQ_Index peaked in both streams and lake water with greater water quality degradation in Beaver and Coldwater creek than other creeks. A significant relationship of WQ_Index with UV absorption and P accounted 84 to 90% of the variations in stream and lake water quality degradation. However, a strong linear relationship (r ²?=?0.81; p<0.01) between UV absorption and P concentration suggested a major contribution of P to the degradation of stream and lake water quality through algal blooming and associated eutrophication.     

Über eine amphidiploideHyoscyamus- Hybride (Hyoscyamus Xgyörffyi Hammer et Melchers,hybr. nov.)

Описывается искусст венный амфидиплоиди ый гибрид Hyoscyamus x györffyiHammer etMelchers, hybr. nov. (2n=102), полученный от скрещивания H.niger (2n=34) с H.albus (2n=68) и сравнивает ся с родительскими ви дами.     

Microsatellite mapping of the <Emphasis Type="Italic">Scr1</Emphasis> locus conferring screwed spike rachis to modify the spatial orientation of spikelets in <Emphasis Type="Italic">Triticum aestivum</Emphasis> L.

In the wheat (Triticum aestivum L.) inflorescence, spikelets are arranged in two opposite rows on the main axis. Spikelet primordia initiate alternately on opposite sides at angles of 180°. Genotypes exhibiting screwed spike rachis (SCR) have been selected as a gene resource having non-standard spike morphology in wheat. Although the SCR phenotype is a prospective gene resource, it is under-utilized. The SCR phenotype is due to the attachment of spikelets to the rachis nodes on the SCR. Seed number and individual kernel size are critical economic parameters and increasing seed number and single grain weight causes competition among the growing seeds. The SCR phenotype is hypothesized to avoid competition by assuring kernel growth space in each floret. The SCR trait has been observed in spikes and peduncles of KM 60-96. The semi-dwarfism of KM 60-96 was GA₃-sensitive, and it was determined by the presence of Rht8 gene. The response of KM 60-96 to microtubule depolymerizing and stabilizing drugs indicated that the SCR phenotype was not caused by a defect in the α-Tubulin gene. The F₂ of two hexaploid hybrids and a pentaploid hybrid between SCR/normal types segregated 3 SCR:1 normal indicating that the SCR phenotype was determined by a single dominant gene, Scr1. Analysis with microsatellite markers indicated that the Scr1 allele was located in the region between markers Xgwm191 and Xgwm371 in chromosome arm 5BL. From the observation of the backcross generation, introgression of the Scr1 allele into locally adapted wheat cultivars is feasible to increase kernel growth space in each spikelet in the limited spike length.     

Effects of warming and increased precipitation on soil carbon mineralization in an Inner Mongolian grassland after 6?years of treatments

Understanding the responses of soil C mineralization to climate change is critical for evaluating soil C cycling in future climatic scenarios. Here, we took advantage of a multifactor experiment to investigate the individual and combined effects of experimental warming and increased precipitation on soil C mineralization and ¹³C and ¹⁵N natural abundances at two soil depths (0–10 and 10–20?cm) in a semiarid Inner Mongolian grassland since April 2005. For each soil sample, we calculated potentially mineralizable organic C (C ₀) from cumulative CO₂-C evolved as indicators for labile organic C. The experimental warming significantly decreased soil C mineralization and C ₀ at the 10–20-cm depth (P?<?0.05). Increased precipitation, however, significantly increased soil pH, NO ₃ ^? -N content, soil C mineralization, and C ₀ at the 0–10-cm depth and moisture and NO ₃ ^? -N content at the 10–20-cm depth (all P?<?0.05), while significantly decreased exchangeable NH ₄ ⁺ -N content and ¹³C natural abundances at the two depths (both P?<?0.05). There were significant warming and increased precipitation interactions on soil C mineralization and C ₀, indicating that multifactor interactions should be taken into account in future climatic scenarios. Significantly negative correlations were found between soil C mineralization, C ₀, and ¹³C natural abundances across the treatments (both P?<?0.05), implying more plant-derived C input into the soils under increased precipitation. Overall, our results showed that experimental warming and increased precipitation exerted different influences on soil C mineralization, which may have significant implications for C cycling in response to climate change in semiarid and arid regions.     

Analysis of genetic diversity and evolutionary relationships among hexaploid wheats <Emphasis Type="Italic">Triticum</Emphasis> L. using LTR-retrotransposon-based molecular markers

The origin, diversity and distribution of hexaploid wheat still remain somewhat unclear. In this study we examined the patterns of genetic diversity and phylogenetic relationships of seven hexaploid wheat species using integration site polymorphism of the LTR retrotransposons. Forty-eight accessions (most of them aboriginal) of seven wheat species from different geographical regions were studied using sequence-specific amplification polymorphisms. Phylogenetic relationships among species were constructed with SplitsTree 4.10 based on Dice’s matrices. Genetic distances between the accessions clustered with PAST software were estimated by principal component analysis. All the accessions differentiated into two main groups, one including European spelt and the other combining common, club and Indian dwarf (shot) wheat with the Asian spelt. The spelt species T. macha, T. vavilovii and spelt spike (speltoid) free-threshing T. petropavlovskyi were intermediate between the two groups. The separation of these spelt species from all other accessions was determined by differences in the A genome. European spelt was subdivided into Central European and Spanish branches. As different genetic pools were characteristic of European and Asian spelt, European spelt could not originate directly from the Asian one. Supposedly, the A genome mostly harbors the species-forming or taxonomically important genes that distinguish spelt species from free-threshing ones, which group together with Asian spelt. Grouping of Asian spelt with free-threshing wheat suggests their close relatedness and confirms the hypothesis that free-threshing hexaploid wheats originated from the Asian spelt ancestor.     

Mercury Extraction from Contaminated Soils by l-Cysteine: Species Dependency and Transformation Processes

A new approach in soil remediation washing techniques is the use of l-cysteine based on the formation of organic complexes. In this study, the applicability of l-cysteine for the mobilisation of different mercury species from contaminated soils was evaluated. Soils were treated with l-cysteine solutions with S?CHg molar ratios of 1, 2, 10, 20, 100 and 200. In 24?h batch experiments, leachates with water could mobilise 1% of Hg. The addition of l-cysteine led to an increase of Hg mobilisation of 42% for soils with inorganically bound Hg. In column experiments, the maximum Hg removal rate was 75%. For soils with organically bound Hg or HgS, only 1?C5% of Hg was mobilised. Thus, the extraction of Hg from soils with l-cysteine is highly dependent on the Hg-binding form. Hg speciation analyses of leachates indicate that Hg?Cl-cysteine complexes are labile complexes which can be easily transformed. Soil samples speciation analysis revealed that reduction to elemental mercury takes place at low S?CHg ratios (1 to 10), assumingly by microbial activity. At higher S?CHg ratios of 10 and 100, precipitation of stable Hg?CS complexes could be observed. These species transformation processes are limitations for considering l-cysteine leaching as a remediation strategy.     

The Inheritance of Morphological and Biochemical Traits Introgressed into Common Wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) from <Emphasis Type="Italic">Aegilops speltoides</Emphasis> Tausch

The genetic control of morphological characters and gliadin composition was studied in two bread wheat lines with introgressed segments from Aegilops speltoides Tausch. It was found that the transferred trait of leaf hairiness is controlled by one dominant gene, non-allelic to the known gene, Hl1. It was localized in 7B chromosome. Whole plant non-glaucousness is under the control of an inhibitor gene, allelic to the gene W1^I of wheat located on chromosome 2B. This gene was found to be epistatic to the gene controlling spike waxlessness. The introgressed gene for spike glume color was found to be allelic to the Rg1 gene located on 1BS of common wheat, but it was linked with another allele of the gliadin locus Gli-B1.     

Increase in the abundance of cladocera at pH 5.1 in experimentally-acidified lake 223, Experimental Lakes Area,Ontario

Lake 223 in the Experimental Lakes Area, northwestern Ontario was experimentally-acidified with H₂SO₄ from 1976 to the present. Cladocerans increased in absolute and relative abundance and in total biomass when the pH of Lake 223 was lowered from 6.7 to 5.1. Comparing the cladoceran community at pH 6.7 (1974) with that at pH 5.1 (1981 to 1983), Daphnia galeata mendotae disappeared, Diaphanosoma birgei became rare, Holopedium gibberum increased in abundance and Daphnia catawba, recorded for the first time in 1980, became abundant. Bosmina longirostris became more abundant. Except for the decline in D. birgei, the changes in cladoceran species composition with acidification are consistent with known responses of these species to low pH. The increase in importance of cladocerans in 1981 to 1983 was at the expense of copepods. It was hypothesized to be caused by the decline in predation by small fish during 1981 to 1983 as acidification reduced minnow populations and inhibited reproduction in trout and sucker. The loss of the population of the invertebrate predator, the opposum shrimp, Mysis relicta, in 1979 had little effect on cladoceran biomass.     

Fish species distribution in relation to lake acidity in Ontario

Survey data from approximately 2,900 Ontario lakes were used to examine the distribution of 12 fish species with respect to lake pH. Yellow perch (Perca flavescens), white sucker (Catostomus commersoni), brook trout (Salvelinus fontinalis), pumpkinseed (Lepomis gibbosus), fathead minnow (Pimephales promelas) and redbelly dace (Phoxinus eos) proved to be tolerant of low pH (pH <6.4). Lake trout (Salvelinus namaycush), common shiner (Notropis cornutus), blacknose shiner (Notropis heterolepis), lake whitefish (Coregonus clupeaformis), walleye (Stizostedion vitreum vitreum) and northern pike (Esox lucius) showed limited distribution in low pH lakes (pH <6.4). The limited distribution of lake whitefish and northern pike likely relates to zoogeographic factors rather than their intolerance to low pH. Lake trout and common shiner occur in lakes susceptible to, and receiving high loadings of acidic deposition. However, without historical data, we cannot determine if their decreased distribution in low pH systems is due to intolerance to low pH.     

Contrasting response of two forest soils to nitrogen input: rapidly altered NO and N2O emissions and nirK abundance

Denitrification represents one of the main microbial processes producing the primary and secondary greenhouse gases nitrous oxide (N₂O) and nitric oxide (NO) in soils. It is well established that abiotic factors like the soil water content and the availability of nitrogen (N) are key parameters determining the activity of denitrifiers in soils. However, soils differing regarding their characteristics such as the content of C_org, the soil texture or the pH value may respond in specific manners to equivalent changes in soil moisture and N input. Thus, short-term incubation experiments were performed to test and compare the capacity of two contrasting Austrian forest soils to respond to mineral N application at increased soil water contents. Soils from the pristine Rothwald forest (rich in C_org) and the more acidic Schottenwald forest (poor in C_org) were amended with either NH ₄ ⁺ -N or NO ₃ ^? -N and were incubated at 40% and 70% water-filled pore space for 4 days. Changes in mineral N pools, nitrite reductase activity and NO and N₂O emission rates were measured, and the abundance and structural community composition of the functional group involved in nitrite reduction were analysed via quantitative real-time polymerase chain reaction and terminal restriction fragment length polymorphism analysis of the nirK gene. Rapid and distinct activity responses to increased soil moisture and altered mineral nitrogen availability were observed in two contrasting forest soils. In both soils, nitrogen oxide emission rates were stimulated by N inputs and, depending on the soil moisture status, either NO or N₂O emission was prevailing. However, different N cycling processes appeared to predominate in either soil under equivalent treatment. Nitrogen oxide emissions peaked following NO ₃ ^? application in Schottenwald soils but were the highest after NH ₄ ⁺ application in Rothwald soils. Denitrifying (nirK) communities differed significantly in Rothwald and Schottenwald soils; however, changes in the community structure were marginal during the short-term incubation. Abundances of nirK genes remained unaffected by N application in either soil. The soil water content affected nirK gene abundances only in Rothwald soil, indicating a distinct reaction of nitrite reducing communities in the two soils.     

Seasonal Monitoring of Hydrocarbon Degraders in Alabama Marine Ecosystems Following the Deepwater Horizon Oil Spill

Following the Deepwater Horizon explosion and crude oil contamination of a marsh ecosystem in AL in June 2010, hydrocarbon-degrader microbial abundances of aerobic alkane, total hydrocarbon, and polycyclic aromatic hydrocarbon (PAH) degraders were enumerated seasonally. Surface sediment samples were collected in October and December of 2010 and in April and July of 2011 along 40?C70-m transects from the high tide to the intertidal zone including Spartina alterniflora-vegetated marsh, seagrass (Ruppia maritima)-dominated sediments, and nonvegetated sediments. Alkane and total hydrocarbon degraders in the sediment were detected, while PAH degraders were below detection limit at all locations examined during the sampling periods. The highest counts for microbial alkane degraders were observed at the high tide line in April and averaged to 8.65?×?10⁵ of cells/g dry weight (dw) sediment. The abundance of alkane degraders during other months ranged from 9.49?×?10³ to 3.87?×?10⁴, while for total hydrocarbon degraders, it ranged between 5.62?×?10³ and 1.14?×?10⁵ of cells/g dw sediment. Pore water nutrient concentrations (NH ₄ ⁺ , NO ₃ ^? , NO ₂ ^? , and PO ₄ ^3? ) showed seasonal changes with minimum values observed in December and April and maximum values in October and July. Concentrations of total petroleum hydrocarbons in sediments averaged 100.4?±?52.4 and 141.9?±?57.5?mg/kg in January and July, 2011, respectively. The presence of aerobic microbial communities during all seasons in these nearshore ecosystems suggests that an active and resident microbial community is capable of mineralizing a fraction of petroleum hydrocarbons.