Sand Substrate Research Articles

Physiological and biochemical parameters: new tools to screen barley root exudate allelopathic potential (Hordeum vulgare L. subsp. vulgare)

Morphological markers/traits are often used in the detection of allelopathic stress, but optical signals including chlorophyll a fluorescence emission could be useful in developing new screening techniques. In this context, the allelopathic effect of barley (Hordeum vulgare subsp. vulgare) root exudates (three modern varieties and three landraces) were assessed on the morphological (root and shoot length, biomass accumulation), physiological (Fv/Fm and F0), and biochemical (chlorophyll and protein contents) variables of great brome (Bromus diandrus Roth., syn. Bromus rigidus Roth. subsp. gussonii Parl.). All the measured traits were affected when great brome was grown in a soil substrate in which barley plants had previously developed for 30 days before being removed. The response of receiver plants was affected by treatment with activated charcoal, dependent on barley genotype and on the nature of the growing substrate. The inhibitory effect was lower with the addition of the activated charcoal suggesting the release of putative allelochemicals from barley roots into the soil. The barley landraces were more toxic than modern varieties and their effect was more pronounced in sandy substrate than in silty clay sand substrate. In our investigation, the chlorophyll content and Fv/Fm were the most correlated variables with barley allelopathic potential. These two parameters might be considered as effective tools to quantify susceptibility to allelochemical inhibitors in higher plants.

Morphological specializations of the epidermis of an angler catfish Chaca chaca (Siluriformes, Chacidae) in relation to its ecological niche: A scanning electron microscopic investigation

The present work was undertaken with the aim to deduce morphological adaptations in skin of an angler catfish Chaca chaca by means of scanning electron microscopy. The fish is nocturnal, bottom dwelling, sluggish, ambush predator, lives in sand, mud, or soft substrates often buried and camouflaged for protection and to feed. The surface of the epidermis is covered with polygonal epithelial cells, each having surface relief of microridges forming intricate patterns. In between epithelial cells irregularly distributed mucous cell openings, randomly distributed epidermal specialized structures, taste buds, and neuromasts are discernible. The epidermal specialized structures are keratinized. These are either irregularly the rounded elevated plaque like or the cone shaped structures. The superficial keratinized cells could frequently be discernible exfoliated at the surface. At intervals, characteristic epidermal projections could be observed. Surface of these projections at intervals is differentiated into short stumpy protuberances, each bearing a taste bud at its summit. Further, near the basal portion of these epidermal projections, conical, or rounded plaque like epidermal specialized structures are also discernible. The surface sculpture of the skin of Chaca chaca is associated with the structural and functional significance and physiological adaptations of the epidermis with respect to its ecological niche.

Ecological factors affecting the accumulation and speciation of arsenic in twelve Australian coastal bivalve molluscs

Environmental contextKnowledge of the pathways by which arsenic is accumulated and transferred in marine ecosystems is scarce. Molluscs are important keystone organisms providing a link between primary producers (micro and macroalgae) and higher trophic levels such as fish. The present study examines the accumulation and species of arsenic in common bivalve molluscs from south-east Australia to understand the cycling of arsenic in marine food webs. AbstractThe present paper reports the whole-tissue total arsenic concentrations and water-soluble arsenic species in 12 common coastal Australian bivalve mollusc species. Mean arsenic concentrations ranged from 18 to 57 µg g−1 dry mass. Planktivores had significantly less arsenic (20–40 µg g−1; 22 ± 3 µg g−1) than did suspension and deposit feeders (36–57 µg g−1; 43 ± 7 µg g−1), with those associated with fine clay–silt sediments (49 ± 7 µg g−1) having significantly more arsenic than those associated with sand substrates (31 ± 11 µg g−1 ). Most planktivores and suspension feeders had similar arsenic species, with high proportions of arsenobetaine (AB) (64–92 %) and relatively low proportions of other arsenic species (0.55–15.8 %). Lower proportions of AB (13–57 %) and larger proportions of inorganic arsenic (6–7 %) were found in deposit feeders, reflecting increased exposure to inorganic arsenic in sediments. The study indicated that at lower trophic levels, organisms feed on algae and suspended matter containing a range of arsenic species including arsenosugars and AB. The implications for arsenic cycling are that as all bivalve molluscs accumulate AB and are a source of AB in benthic food webs. Because all bivalve molluscs also contained appreciable concentrations of arsenoriboses, precursors are present for the de novo synthesis of AB. As well, deposit feeders have higher proportions of inorganic arsenic that can be metabolised to different end products when ingested by higher trophic organisms

Plant characteristics determination in sand pits near Moscow

Sand pits are man-made landforms, where vegetation selfrestoration becomes very difficult. An in-depth study of sand pits’ flora and vegetation must be done in order to restore the complete canopy on sand substrate, which prevents the movement of slopes. In Zvenigorod and Dzerzhinsk sand pits, aged about 70 years, we have studied the slopes with northern and southern exposure for 3 years. The article shows that all the 131 species which we have found in the surveyed area were species of vascular plants. Projective cover degree made up 20-30% which, in general, is a typical characteristic of sandy terrain. Hemicryptophytes dominate the spectrum of life forms by K. Raunkiaer in our research. According to the classification of life forms by I. G. Serebryakov, sand slopes are dominated by herbaceous perennial polycarpics, among which long and short rhizome plants and tap rooted plants are in majority. A significant proportion of tap rooted plants is due to their high degree of adaptation to strong light conditions and resistance to drought. Long-and short rhizome plants tend to loose substrates and soft soils.

Aquatic insects in organic and inorganic habitats in the streams on the Central Brazilian savanna

A major part of the mechanisms that affects species distribution is related to environmental conditions. Within a stream channel the accumulation of substrates like litter, roots, stones, gravel and sand create habitats that act as shelter and/or food source to aquatic communities, in this way supporting, or not, the establishment of different species. Based on this fact we verified the structure of aquatic insect communities in organic and inorganic habitats within Cerrado streams. Tested for differences on genera richness (i), individual abundance (ii) and genera composition (iii), and also (iv) verified if there are any indicator genera, which are faithful and specific to organic or inorganic habitats. Sampled organic (litter) and inorganic (sand and gravel) substrates in five sections of three streams and collected individuals of the orders Ephemeroptera, Plecoptera, Trichoptera, Odonata and Heteroptera (EPTOH). Community composition differed between habitats, with organic ones having higher richness and abundance, besides being the only habitat that presented faithful and specific genera (six). It is argued that this difference may be caused due to shelter and food supply provided by organic substrates.

CARPOSEMINAL BIOMETRY AND GERMINATION OF Cabralea canjerana (Vell.) Mart.

Cabralea canjerana is a species that has ecological and economic importance for the Southern Brazil. This study aimed to characterize the biometry of fruits and seeds as well as the C. canjerana germinative process submitted to different substrates and temperatures. The biometric characteristics of fruits and seeds were analyzed with the aid of digital caliper. In the germination test, the substrates blotting paper, sand and vermiculite, and the temperatures of 20, 25 and 30 ºC were used. The germination percentage, mean germination rate (MGR), mean germination time (MGT), synchronization index (SI), fresh mass (FS) and dry mass (DM) of seedlings were assessed. The highest germination percentages occurred for vermiculite at three temperatures, blotting paper at 25 °C and sand at 20 and 30 °C. There was seedling formation in all treatments. The use of the sand substrate and the temperatures of 25 and 30 °C provided lower mean values of MGT and SI and higher mean values of MGR. The highest DM occurred with sand at the temperature of 20 ºC. The biometric characteristics of fruits and seeds varied. We recommend the use of vermiculite at temperatures of 20, 25 and 30 ºC, blotting paper at 25 °C and sand at 20 and 30 °C for germination tests.Keywords: Meliaceae, native species, germination potential, temperature, substrate. Resumo:Biometria carpo seminal e germinação de Cabralea canjerana (Vell.) Mart. Cabralea canjerana é uma espécie que possui importância ecológica e econômica para o Sul do Brasil. Este estudo objetivou caracterizar a biometria de frutos e sementes, assim como o processo germinativo de C. canjerana submetido a diferentes substratos e temperaturas. Analisaram-se as características biométricas de frutos e sementes com auxílio de paquímetro digital. No teste de germinação, foram utilizados os substratos papel mata-borrão, areia e vermiculita e as temperaturas de 20, 25 e 30 ºC, avaliando-se a porcentagem de germinação, velocidade média de germinação (VMG), tempo médio de germinação (TMG), índice de sincronização (I), massa fresca (MF) e massa seca (MS) de plântulas. As maiores porcentagens de germinação ocorreram com vermiculita nas três temperaturas, papel mata-borrão a 25 °C e areia a 20 e 30 °C. Houve formação de plântulas em todos os tratamentos. O uso do substrato areia e das temperaturas de 25 e 30 ºC proporcionou menores médias de TMG e I e maiores médias de VMG. A maior MS ocorreu utilizando-se areia sob temperatura de 20 ºC. Ocorreu variação das características biométricas de frutos e sementes. Recomenda-se a utilização de vermiculita nas temperaturas de 20, 25 e 30 ºC, papel mata-borrão a 25 °C e areia a 20 e 30 °C para testes de germinação.Palavras-chave: Meliaceae, espécie nativa, potencial germinativo, temperatura, substrato.

Respostas comportamentais do camarão de água doce de acordo com o manejo alimentar em populações mistas e monossexo

Foram avaliados os efeitos de dois métodos de alimentação (a lanço e em comedouros) e sua influência no comportamento de populações mistas (Mi), monossexo fêmea (Mf) e monossexo macho (Mm) de Macrobrachium rosenbergii nas fases clara e escura do dia. Foram analisadas 12 condições experimentais, com quarto repetições cada uma, totalizando 192 animais observados. As unidades experimentais consistiram em 8 aquários (250 L; 50 x 50 x 100 cm) com substrato de areia fina. Dados comportamentais foram coletados usando método de amostragem focal instantí­¢neo. A oferta a lanço, em todas as composições populacionais, induziu a maiores ní­­veis dos comportamentos de exploração, limpeza, enterramento, inatividade, entocamento, agonismo, natação e ingestão de alimento, indicando que os animais encontraram mais oportunidades para expressão de seus comportamentos com o espalhamento da ração. Como exceção, o comportamento de entocamento em Mm e agonismo em Mf foram semelhantes para ambos os tipos de manejo alimentar. O cultivo Mf apresentou maiores ní­­veis de agonismo que Mm e Mi. Neste estudo, os resultados indicam que, em todos os tipos de composição populacional, a alimentação a lanço favoreceu o bem-estar do animal, exceto para o cultivo Mf, o qual apresentou altos ní­­veis de agonismo em ambas as formas da estratégia alimentar.

ASPECTOS REPRODUTIVOS E POTENCIAL DE EMERGÊNCIA DE PLÂNTULAS DE <i>Cryptostegia madagascariensis</i> Bojer ex Decne

Invasão biológica é o processo no qual um organismo exótico, quando adaptado, passa a competir com as espécies nativas causando graves impactos. A espécie Cryptostegia madagascariensis Bojer ex. Decne, introduzida no Brasil com fins paisagísticos, tem se revelado uma espécie invasora bastante agressiva no bioma caatinga formando maciços autorregenerantes principalmente em áreas degradadas e às margens dos cursos de água e lagoas temporárias. Objetivou-se com este estudo avaliar aspectos reprodutivos (através da caracterização biométrica) e o potencial de emergência de plântulas de Cryptostegia madagascariensis. Para a caracterização biométrica, frutos (com coloração verde) e sementes (com coloração branca) tiveram suas dimensões mensuradas, aferindo-se ainda o número de sementes por fruto e a massa fresca de frutos e sementes. Para a avaliação da influência da posição e profundidade de semeadura na emergência de plântulas, as sementes foram semeadas em areia esterilizada com o hilo para baixo, para cima e para o lado, nas profundidades de 0,5; 1,0; 1,5; 2,0; 2,5 e 3,0 cm. A elevada produção de sementes muito leves por fruto e, por conseguinte, de sementes por indivíduo potencializa o caráter invasor de Cryptostegia madagascariensis. A emergência e o vigor de plântulas de Cryptostegia madagascariensis são reduzidos pelo aumento da profundidade.

The role of topography, river size and riverbed grain size on the preservation of riverine mollusk shells

The degree to which a group of fossils reflects the original community from which it was derived can be estimated by comparing living communities with locally accumulated dead remains. Such live–dead approaches (LA/DA) can provide important baseline information on the ecological structure of ancient freshwater systems. This study explored variations in composition, richness, evenness and rank-abundance in live and dead mollusk assemblages recovered from the Ibicui River Basin, southern Brazil. LA/DA was related to topography, river size, and sediment grain size, separated respectively into plain (altitude 0–100 m) versus slope (100–500 m), small versus medium-large stream orders, and gravel versus sand substrate. Positive correlation between LA and DA species composition was significant only in large rivers. Slope areas showed LA/DA species compositions that were significantly different, whereas the communities from sand and gravel substrates were quite similar. Important factors that affected live/dead similarity in the study area included (1) destruction of thin, fragile shells of dead animals by acidic waters that are common in the region, (2) downstream drift of small spherical shells from species common in slope areas, such as Potamolithus sp., and (3) high abundances of invasive species in the local death assemblage, especially in large rivers. High fidelity in large rivers is caused by the presence of favorable habitats for bivalve communities. Coarse sediments are an important driver of macro invertebrate diversity, acting as shell traps that slow the downstream drift of bivalve remains and improve the preservation of fluvial mollusks. The preservation potential of dead assemblages of the Ibicui River showed that fossil assemblages are useful tools for recognizing ancient riverscapes, such as flat areas with sandy substrates.

Hydric environmental effects on turtle development and sex ratio

Experimental and field studies of different turtle species suggest that moisture influences embryonic development and sex ratios, wetter substrates tend to produce more males, and drier substrates produce more females. In this study, we used Trachemys scripta elegans to test the effect of moisture on embryonic development and sex ratios. T. s. elegans eggs were incubated under different temperature and moisture regimes. We monitored embryonic development until stage 22 (after sex determination) and, for the first time, we estimated sex ratios using a male-specific transcriptional molecular marker, Sox9. Among treatments, we found differences in developmental rates, egg mass, and sex ratio. Embryos developed slowly in cooler and wetter sand substrate while water uptake by the eggs was significantly greater on wetter substrates. Developmental differences were due to moisture interacting with temperature where increased water content of the sand resulted in temperatures that were 2–3°C lower than air temperatures. The coolest and the wettest substrates produced 100% males compared to 42% males from the warmest and driest treatment. Further, we found that embryonic growth appears to be more sensitive to temperature at earlier stages of development and to moisture at later stages. This study shows how moisture may change the incubation conditions inside nests by changing the temperature experienced by eggs, which affects development, growth and sex ratios. The results of this study highlight the importance of including moisture conditions when predicting embryo growth and sex ratios and in developing proxies of embryonic development.

English

Caesalpinia ferrea Mart. Ex Tul. is a tropical arboreal species used in naval and civil construction, and in the recovery of degraded areas. The substrate used and temperature can interfere directly in the germination of this species. This work aimed to evaluate the influence of different substrates and temperature regimes on the seed germination potential and initial growth of C. ferrea seedlings. The experiment was conducted at the Plant Propagation Laboratory of the Federal University of Alagoas, Brazil. A completely randomized design was used in a 5 × 4 factorial scheme with five substrates (paper roll, paper, sand, and vermiculite) and four temperatures (20, 25, 30 and 35°C). The evaluated characteristics were first count of germination, germination, germination speed index, dry mass, and seedling length. Results showed that C. ferrea seeds could germinate under different temperatures and substrate conditions. The sand substrate and the temperature of 30°C are excellent for evaluating the physiological quality of the seeds. Key words: Physiological potential, substrate, temperature.

Age‐0 blue catfish habitat use and population demographics in the middle Mississippi River

AbstractThe demographics (e.g. hatch time, growth and mortality) and habitat (macrohabitat and mesohabitat) use of age‐0 blue catfish Ictalurus furcatus (Lesueur) were evaluated in the un‐impounded reach of the middle Mississippi River during 2003–2010. Each year, island complexes and adjacent main river habitats were trawled, and 7,373 age‐0 blue catfish (10–144 mm total length) were collected. Blue catfish hatch timing varied slightly across years and generally began in June and ended in August. Age‐0 blue catfish growth rates and instantaneous mortality rates differed among years. Catch rates of age‐0 blue catfish were highest in side channels and around islands, whereas main channel habitats were infrequently occupied. Regarding mesohabitat use, age‐0 blue catfish frequently occupied low velocity areas (i.e. 0.3–0.4 m/s) of shallow depth (i.e. 1–4 m) and sand substratum. This study has provided insight into age‐0 blue catfish population dynamics and has highlighted the importance of specific habitat characteristics in large rivers that may aid in recruitment of this species.

Perbandingan Morfometrik dan Meristik Lamun Halophila ovalis di Perairan Pulau Serangan dan Tanjung Benoa, Bali

Halophila ovalis is a type of seagrass that has a round oval shape that can live in waters that have a muddy sand substrate. Morphometric and meristic are used to describe the waters where seagrass life seen from the morphology of leaves, rhizomes and roots. Morphometrics is a measure to determine the quantitative morphology of an organism structure and Meristik is a calculation to know the sum of a part of an organism.This research was conducted in December 2016-February 2017 with purposive sampling method at 10 observation station in Serangan Island and Tanjung Benoa. Data analyzed with descriptive analysis, Sturges criteria and Similarity Index of Morisita. Based on the results of leaf length study ranged from 9.4-51.3 mm, leaf width ranged from 6.7-19.8 mm, the number of leaf bones ranged from 10- 21 pairs, the length of the petiole ranges from 4.5 to 55.6 mm, the diameter of the petiole ranged from 0.03 - 1.4 mm, the length of rhizoma ranged from 6.2- 41.2 mm, diameter of rhizoma ranged from 0.04 -1.8 mm and root length ranged from 7.5-89 mm. By categorizing morfometrik-meristic seagrass H. ovalis, hence formed value of each research station gaze which will describe similarity between stations. In the similarity index of morisita, the research station in Serangan and Tanjung Benoa waters has similarity of morphometry - meristic very similar to 92.8% equality.

Enhanced photocatalytic activity of ZnO nanoparticles grown on porous silica microparticles

ZnO nanoparticles (NPs) have been synthesized on porous silica microparticles, namely sand microparticles using the sol–gel technique. The ZnO NPs grown on the multifaceted surface of porous silica microparticles were applied as photocatalyst for the degradation of methylene blue (MB) in aqueous solution. The enhanced rate constant observed was due to two reasons. Firstly, the multifaceted surface of the sand substrate provided fixed space for growth space which prevented agglomeration of the ZnO NPs photocatalyst, thus maintaining a large surface area. Secondly, the presence of nanopores on the sand surface provided adsorption sites for MB molecules to be in the vicinity of the photocatalyst. The photocatalytic activity was significantly enhanced where photodegradation efficiency of supported ZnO NPs reached 71.7% compared to 48.2% for unsupported ZnO NPs under UV light irradiation within 150 min. The values of k increased from 4.3 × 10−3 min−1 to 8.6 × 10−3 min−1 for unsupported and supported ZnO NPs, respectively.

It's just sand between the toes: how particle size and shape variation affect running performance and kinematics in a generalist lizard.

Animals must cope with and be able to move effectively on a variety of substrates. Substrates composed of granular media, such as sand and gravel, are extremely common in nature, and vary tremendously in particle size and shape. Despite many studies of the properties of granular media and comparisons of locomotion between granular and solid substrates, the effects of systematically manipulating these media on locomotion is poorly understood. We studied granular media ranging over four orders of magnitude in particle size, and differing in the amount of particle shape variation, to determine how these factors affected substrate physical properties and sprinting in the generalist lizard Eremias arguta We found that media with intermediate particle sizes had high bulk densities, low angles of stability and low load-bearing capacities. Rock substrates with high shape variation had higher values for all three properties than glass bead substrates with low shape variation. We found that E. arguta had the highest maximum velocities and accelerations on intermediate size particles, and higher velocities on rock than glass beads. Lizards had higher stride frequencies and lower duty factors on intermediate particle size substrates, but their stride lengths did not change with substrate. Our findings suggest that sand and gravel may represent different locomotor challenges for animals. Sand substrates provide animals with an even surface for running, but particles shift underfoot. In contrast, gravel particles are heavy, so move far less underfoot, yet provide the animal with an uneven substrate.

The contribution of environmental factors to fish assemblages in the Río Acahuapa, a small drainage in Central America

ABSTRACT The ichthyofauna of the Río Acahuapa was analyzed sampling 17 sites that included the basin main channel and its tributaries. Fish were collected using dip-nets, seine-nets and electrofishing. Fish standard length and species abundance were recorded. Species origin and salinity tolerance criteria were used to classify fish species. Water physicochemical variables, habitat structure and sampling sites elevation were recorded. A total of 33 fish species were registered, 12.1% are primary, 45.5% are secondary and 42.4% are of marine derivation. Fish species richness declined with increase of elevation (R2=0.55, p=0.0006). Two assemblages of fishes were identified: the first one associated to sites of low elevations (19-184 masl), composed mainly of secondary and marine-estuarine fish species related with high temperature, water velocity, river width, dissolved oxygen and low sand and silt substrate cover; the second one associated to sites of middle and higher elevations (185-519 masl), composed by primary and secondary freshwater fishes related with high pH, logs and rocks substrate cover. In summary, elevation and environmental variables contributed to the composition and distribution of fish in the Río Acahuapa.

Influence of substrate base on sports field covered with bermuda grass

The sports field consists of three layers (sub-base, base (substrate) and grass). The base is responsible for the radicular development of the grass, directly influencing the characteristics that provide quality, water drainage and lawn durability and allows athlete performance. The construction of sports field base generally follows USGA (United States Golf Association) recommendations for golf course greens. Sand is the main component based on its high capacity for drainage. This study aimed to define the best composition of the base for sports fields covered with Bermuda grass. The following treatments were evaluated: T1: sand; T2: sand (80%) + peat (20%); T3: sand (90%) + clay soil (10%); T4: sand (70%) + sandy soil (30%) during 12 months. The experimental design consisted of a randomized block design, with a 4 x 12 factorial design (treatments x months), with 3 replicates and each plot measuring 3 x 4 m. During one full year, the following parameters were evaluated: surface traction of the turf, mechanical resistance of the base to penetration, humidity of the base, concentration of nutrients in grass clippings, and chemical analysis of the base. The tallest grass occurred in substrate of sand mixed with peat. This mixture also promoted the highest N and P levels in the leaves of Bermuda grass. Playability of the sports field, as determined by mechanical strength and surface traction, was unaffected by the type of substrate. The presence of peat, sand and clay soil mixed with sand promoted greater water retention at the base.

Water beetles (Coleoptera) of coastal areas of the Bolshezemelskaya Tundra, extreme northeastern Europe

ABSTRACTThe fauna of water beetles in coastal areas of the Bolshezemelskaya Tundra and on the Vaygach and Dolgiy islands, Pechora Sea, comprises a total of 42 recorded species; in local faunas, the number of species decreases northward from 19–26 in southern mainland tundra to nine in typical tundra of the Vaygach Island. The faunal similarity between pairs of areas is 21%–52% (39%–52% between mainland areas). The family Haliplidae is represented by three species, Dytiscidae – 32 species, Helophoridae – four species, Hydrophilidae – two species and Hydraenidae – one species. Most of the species have large ranges both longitudinally and latitudinally. Cryophile species are rather few (five species, 12%). There are clear differences between the beetle assemblages of weakly brackish lakes marshes and waterbodies of the bedrock coast. The strongest preferences for particular habitats have been revealed in species associated with sand substrates in waterbodies or with the floodplain of a large river. The male genitalia and male protarsal claws of Agabus luteaster (Zaitzev, 1906), recently recorded as new to Europe, are illustrated for the first time as well as Ochthebius kaninensis Poppius, 1909.

The growth and population dynamics of seagrass Thalassia hemprichii in Suli Waters, Ambon Island

The objectives of the research were to determined growth of rhizome, age structure, recruitment rate, and mortality rate of Thalassia hemprichii. Data were collected by using reconstruction technique which the measurements were based on past growth history. The age of seagrass was based on plastochrone interval. The recruitment rate was estimated by age structure of living shoots while mortality rate was estimated by age structure of dead shoots. The research was conducted on coastal waters of Suli where divided into two stations with different substrates, namely mixed substrates of sand and mud (S1) and mixed substrates of sand and coral fragment (S2). The growth rate of horizontal rhizome ranged from 4.15-8.68 cm.year-1 whereas the growth rate of vertical rhizome was 1.11-1.16 cm.year-1. The average age of T. hemprichii varied between 3.22-4.15 years. The youngest shoots were found at age 0.38 years and the oldest shoots were 7.82 years. Distribution of age was polymodal which reflecting cohort. The recruitment rate ranged from 0.23-0.54 year-1. Otherwise, the mortality rate ranged from 0.21-0.26 year-1.Seagrass population of T. hemprichii in Suli Waters indicated an increasing condition which shown by higher recruitment rate than mortality rate.

Phosphorus availability and fractionation vary among forest site types in reconstructed oil sands soils

We investigated relationships between phosphorus (P) availability and fractionation and growth of lodgepole pine (Pinus contorta var. latifolia Engelm. ex S. Watson) and white spruce (Picea glauca (Moench) Voss) in the Athabasca oil sands region. The study sites had peat – mineral soil mix (PMM) as cover soil over a tailings sand substrate planted to pine or an overburden substrate planted to spruce. Available P was determined using a modified Kelowna extraction and sequentially extracted to obtain exchangeable, Fe- and Al-bound, Ca- and Mg-bound, organic, and residual P. The organic P content in PMM explained 83% and 65% of the variations in available P in the pine and spruce sites, respectively. Phosphorus bound to Fe and Al in PMM was also positively related to available P on pine sites (p < 0.001) but not on spruce sites. Available P in PMM was correlated with aboveground biomass increment of spruce (p < 0.05) and explained 78% of the variation in foliar P. Foliar P in both pine and spruce was lower than the adequate level for tree growth. Low foliar P and available P in PMM affect the successful establishment of pine and spruce trees on the reclaimed sites, and proper P nutrition management is important to overcome P limitation in reclaimed soils.