Sand Substrate Research Articles

Emergence and initial growth of Mimosa bimucronata (DC) O. KTZE. seedlings at different depths and position of sowing

Mimosa bimucronata (DC) O. KTZE. (maricá), belong to the family Fabaceae is a forest species found in Latin America. This species has been used in landscaping, reforestation and restoration of degraded areas and permanent preservation. The present work aimed to verify the effect of the position of the seed and the depth of sowing in the emergence and initial growth of seedlings of M. bimucronata. The experiment was carried out in a completely randomized design with four replications including 25 seeds per treatment. Different positions of the seeds were used in the sand substrate: downward facing (HB) thread; facing the side, forming an angle of 90 ° to the imaginary axis with the substrate (HL); and upward facing wire (HC), at seeding depths of 1, 2, 3, 4, 5 and 6 cm. The following variables were evaluated: emergence percentage, first count and emergence speed index, seedling length and dry mass. The results showed that HL at a depth of 1 cm sowing produces higher vigor seedlings.

Germinação de sementes de Ceiba speciosa coletadas em Brejo de Altitude

Ceiba speciosa (A. St.-Hil.) Ravenna (Malvaceae) é uma espécie arbórea nativa em florestas brasileiras, indicada na recomposição de áreas degradadas e na indústria de estofados. Com este trabalho, objetivou-se verificar substratos e temperaturas favoráveis à germinação de sementes de paineira coletadas em um remanescente florestal de Brejo de Altitude na Paraíba. O delineamento experimental utilizado foi o inteiramente casualizado, num arranjo fatorial 2 × 4, constituídos pelas combinações de duas temperaturas (25 e 30 °C) e quatro substratos (areia, vermiculita, terra e papel mata-borrão), com quatro repetições de 25 sementes cada. Foram analisadas as seguintes características: teor de água (%) das sementes, porcentagem de emergência, tempo médio de emergência, porcentagem de plântulas normais e índice de velocidade de emergência (IVE). Houve efeito significativo para a interação temperatura × substrato para todas as variáveis, exceto IVE. Os substratos vermiculita e areia sob a temperatura constante de 25 °C são recomendados para a condução de testes de germinação de sementes de Ceiba speciosa. A temperatura de 30 °C pode ser indicada quando associada ao substrato vermiculita. O substrato sobre papel mata-borrão não é indicado para a germinação de sementes dessa espécie. Sugere-se um estudo com sementes de diferentes populações dessa espécie para confirmar a influência da procedência da semente no seu desempenho germinativo quando submetidas a fatores ambientais associados, como temperaturas e substratos.

Dormancy Breaking and the Influence of Temperature, Substrate and Light on Germination of Colubrina glandulosa Seeds

This study aimed to define a methodology that, when combined with temperature, can overcome the dormancy and also to determine the adequate substrate and light conditions for germination of Colubrina glandulosa Perkins, contributing to seed analysis and restoration projects. In the experiment of dormancy and temperature, seeds were immersed in sulfuric acid for 30, 60, 90, 120 and 150 minutes and set to germinate at temperatures of 20-30 °C, 25 °C and 30 °C. The used substrates were sand, vermiculite, Tropstrato® substrate, coconut powder, blotting paper and paper towel. As for the light supplied, the seeds were subjected to four luminosity regimes: white light, far-red light, red light and light absence. Temperatures of 20-30 °C and 30 °C achieved better results, with exposure in sulfuric acid for 120 and 150 minutes. The substrates sand and vermiculite were the most suitable. The species germinated in all light regimes treatments used.

Evaluation of rotation of Ficus benjamina types in growing environments

This article presents the results of research on the evaluation of rooting performance in the growing media of Ficus species in the interior. In the propagation of Ficus species, the vegetative method was selected and experimental work was carried out in growing media of 4 species. Sand (control), soil, Indole Butyric Acid (IBA) (4,000 mg/l) was obtained as cultivation media. The room temperature at which the experiments were placed was monitored and controlled. During rooting of cuttings, the room temperature was maintained at 18–24 ° C. Humidity was maintained at 40-50%. Soil and sand moisture were maintained at 30-40 degrees depending on temperature (based on the readings of the soil moisture meter). Observations were made and recorded every 3–5 days to determine the vegetative rooting rate of the Ficus Benjamin plant. Taking into account the transpiration of the plant and the evaporation of water into the air, 3-5 ml of water was poured in 10-12 days. As a result of these observations, the timing of vegetative rooting and irrigation norms were determined. Rooted plants were planted in peat, soil, humus feed, coarse sand substrate in a 1:1:1:1 ratio. In selecting these plants, a number of important indicators such as their growth patterns, leaf shape, habitat, drought tolerance, shade tolerance, soil moisture and composition were analysed and conclusions were drawn based on the findings.

Manifestation And Endoparacitic Intensity On Gonggong Conch (Laevistrombus turturella)

Habitat the gonggong conch (Laevistrombus turturella) also known as Dog conch is a species from the Gastropod class that can be found in shallow waters with muddy sand substrate. In Kepulauan Riau Province, these animals are hunted by fishermen to sell to consumers since gonggong conch is a favourite culinary in this province. The availability of conch in the market has only relied on natural catches. The high consumption and natural fluctuations have decreased the conch population. To maintain the sustainability of the dog conch, it is necessary to carry out the cultivation activities. The cultivation begins with the selection of quality broodstock. The gonggong conch of natural origin needs to be determined before cultivation, in order to prevent the entry of disease in the cultivation system i.e. parasites. This study includes the determination, prevalence and infection intensity of endoparasites in conch from Madong Bay, Tanjungpinang. The results showed that the total length of the conch shells ranged from 55.5 to 79.5 mm with an average length of 67.72 mm and a frequency mode of 64.6 mm. The sex ratio between male and female conch is 1:1.1 (not ideal) n=30. Two kinds of parasites were found in the digestive tract of gonggong conchs are conoidacid oocysts and trematode sporocysts. The number of endoparasites, prevalence and intensity in wild caught has high numbers involving conoidacid oocysts (prev=100%; I=48.23 ind/conch) and trematode sporocysts (prev=100%; I= 135.33 ind/conch). It was concluded that the level of endoparasites infection in the dog conch from the Madong Bay was categorized as moderate-to-severe.

Determination of the Initial Value Ranges of Nonlinear Solutions for a Log Ratio Bathymetric Inversion Model and Bathymetry Retrieval

The log-ratio model (LRM) with three model parameters ( ${\boldsymbol{n}}$ , ${{\boldsymbol{m}}_1},$ and ${{\boldsymbol{m}}_0}$ ) has been widely used in shallow water bathymetry of multispectral images. At present, obtaining LRM model parameters by optimization algorithms depends on the setting of initial values [ ${\boldsymbol{n}}(0)$ , ${{\boldsymbol{m}}_1}(0),$ and ${{\boldsymbol{m}}_0}(0)$ ] or initial value ranges. However, how to set the initial value can obtain model parameters more effectively and credibly, and the significance of each initial value in the optimization process is very important for LRM bathymetric retrieval method. In this article, remote sensing images and bathymetric data were used to determine the initial value ranges of credible model parameters, and then the sensitivity of each parameter was analyzed in the algorithm optimization process from the partial differential perspective, and the bathymetry was retrieved in the sea area near Ganquan Island. The results show that according to the partial differential analysis of model parameters, ${\boldsymbol{n}}$ , with the smallest change rate in three LRM parameters and the rate of ${{\boldsymbol{m}}_1}$ and ${{\boldsymbol{m}}_0}$ is at least five times of it. So ${\boldsymbol{n}}(0)$ needs more iterations to achieve the optimal. Therefore, the initial value ${\boldsymbol{n}}(0)$ determines whether the optimization method can obtain credible LRM model parameters and the algorithm convergence speed. And when ${\boldsymbol{n}}(0) \in ({1/{{\boldsymbol{R}}_{{{\bf min}}}}, 1000} ]$ ( ${{\boldsymbol{R}}_{{{\bf min}}}}$ is the minimum reflectance in blue and green bands), there must be a credible model parameter solution. The bathymetric retrieval results of the sea area with coral and sand substrates show the applicability of our initial value ranges in different substrate area.

Comparison of Morphological and Anatomical Characteristics of Taxus chinensis var. mairei Seedlings Root under Waterlogging Stress in Different Substrates

Four different ratios of river sand, ceramic pellets, vermiculite and perlite (1:1), and field soil were selected as the substrates in this experiment, and four gradient levels of root waterlogging, half waterlogging, full waterlogging and normal were set to investigate the effects of different gradients of waterlogging stress on the root morphology of Taxus chinensis var. mairei seedlings under different substrates. In this study, the root anatomical structure of Taxus chinensis var. mairei under different waterlogging stress was observed by the paraffin section method. The roots of T. chinensis var. mairei were diarch, with no pith and resin canals. There was a large number of tannins in the pericycle of the aerial adventitious roots of seedlings adapted to waterlogging. Also, the endodermis has obvious casparian strip thickening, and there were 4-5 layers of large parenchymatous cells in the close to the inner side of the pericycle in the vascular cylinder, which could increase the storage capacity, and transport capacity of the root. Under the treatment of root waterlogging stress, the development of plant roots in the mixed substrate of vermiculite and, perlite was the earliest. Under half waterlogging stress, T. chinensis var. mairei seedlings treated with various substrates all could better adapt to the environment of waterlogging stress. Under the stress of fully waterlogging, the roots of seedlings planted in river sand substrate developed secondary growth.

KEANEKARAGAMAN DAN DOMINANSI RUMPUT LAUT HIDROKOLOID PADA SUBSTRAT YANG BERBEDA DI PERAIRAN PANTAI KARANGTENGAHNUSAKAMBANGAN CILACAP

Perairan Pantai Karangtengah Nusakambangan Cilacap memiliki berbagai macam tipe substrat yaitu pasir, karang, dan campuran. Kondisi pantai dengan banyak tipe substrat memungkinkan berbagai spesies rumput laut untuk tumbuh. Informasi terkait keanekaragaman dan dominansi spesies rumput laut penghasil hidrokoloid di perairan Pantai Karangtengah belum banyak diteliti. Penelitian ini bertujuan untuk mengetahui keanekaragaman dan dominansi rumput laut penghasil hidrokoloid pada substrat yang berbeda di perairan Pantai Karangtengah Nusakambangan Cilacap. Penelitian ini menggunakan metode survei dengan teknik pengambilan sampel yaitu metode transek acak terpilih. Sebanyak enam garis transek dibuat secara tegak lurus dengan garis pantai dan jarak antar transek 25 m. Setiap transek dibuat tiga plot yang masing-masing plot berukuran 1x1 m berdasarkan substratnya (karang, pasir, dan campuran). Parameter utama yang diamati yaitu jumlah biomassa dan jumlah spesies. Parameter pendukung yang diamati adalah faktor lingkungan yaitu temperatur, salinitas, pH, kecepatan arus dan kedalaman. Jumlah spesies rumput laut hidrokoloid yang ditemukan sebanyak 10 spesies rumput laut dengan rincian 5 spesies penghasil alginat, 3 spesies penghasil agar, dan 2 spesies penghasil karaginan. Nilai indeks keanekaragaman di perairan pantai karangtengah antara 0,6-2,0 tergolong keanekaragaman sedang. Nilai indeks dominansi di perairan Pantai Karangtengah antara 0,2-0,6 tergolong dominansi rendah.

Primer registro del lenguado de Herre, Aseraggodes herrei (Pleuronectiformes: Soleidae), en la isla Malpelo, Pacífico colombiano

A pesar de ser un género diverso con un total de 53 especies, Aseraggodes solo tiene registros confirmados de una especie en el Pacífico Oriental Tropical (POT). En esta nota se presenta el primer registro del lenguado de Herre, A. herrei, para Colombia, a partir de dos especímenes observados a 24 m de profundidad, en el costado oriental de la isla Malpelo. Ambos individuos estaban camuflados sobre sustrato de arena gruesa. Diferenciarlos del sustrato fue difícil, lo que podría explicar, junto con la poca disponibilidad de hábitat, por qué esta especie no había sido registrada previamente para la isla. Este registro amplía la distribución geográfica insular de A. herrei más allá de los archipiélagos de Galápagos y de Revillagigedo y de la isla del Coco en el POT. Además, resalta la importancia de las especies visualmente crípticas y estrechamente asociadas al bentos en los inventarios de riqueza íctica.

Evaluation of pre-germination treatments in Carapa guianensis AUBL

Understanding seed germination of native forest species of the Tropical wet forest is essential for ecosystem regeneration and conservation, which have been affected by the exploitation of wood and non-wood forest products. Carapa guianensis Aulb. (Meliaceae) has been exploited due to the high quality of its wood and seeds. Particularly, the latter is a source of a medicinal oil of high value to the pharmaceutical industry. The indiscriminate use of this species has reduced its population size; therefore, scientific knowledge of its sexual propagation in nurseries is vital. This research aimed to evaluate seed germination of C. guianensis under different pre-germination treatments and substrates at the Centro de Investigación El Mira of AGROSAVIA. Pre-germination assays were conducted in a split-plot design with a random distribution of four repetitions. The cumulative germination percentage (CGP) and mean germination time (t50) were calculated and analyzed through an ANOVA, and Tukey’s multiple comparison test using InfoStat V.2016. Significant differences for CGP among treatments (p<0.0001) and interactions (p<0.0096) were found. The highest germination percentage (61%) was achieved in S1+T4; however, the T50 did not show significant differences (p=0.24). This research demonstrates that the highest germination percentage is achieved through a scarification treatment with imbibition in sand substrate under the agroclimatic conditions of Tumaco.

Difference of ecological half-life and transfer coefficient in aquatic invertebrates between high and low radiocesium contaminated streams

The Fukushima accident emitted radioactive substances into the environment, contaminating litter, algae, sand substrate, aquatic invertebrates, and fish in freshwater streams. Because these substances have substantial effects on stream ecology over many years, it is necessary to clarify the diffusion and decay mechanisms of radiocesium. The transfer coefficient differed among aquatic invertebrate groups, likely due to the differences in habitat. The ecological half-life of cesium was longer where the air dose rate was lower. The transfer coefficient was also higher in areas with lower air dose rate. The radiocesium concentration in algae was inversely related to stream current velocity in the radiocesium-contaminated area. However, this relationship was not observed in the lower air dose rate area: the radiocesium concentration in algae in the rapid-velocity areas tended to be higher than that in the slow-velocity areas. This reverse trend would lead to a longer period of freshwater contamination. The radiocesium concentration would continue to decrease in highly contaminated areas, but it would be difficult to reduce the radiocesium concentration in less-contaminated areas because different contamination mechanisms are at work. Controlling the water flow is key to regulating radiocesium concentration in freshwater ecosystems.

Morphological function of toe fringe in the sand lizard Phrynocephalus mystaceus

Toe fringe is the most typical morphological feature of lizards adapted to sandy environments, and it is simple in shape, can evolve repeatedly, and has a high degree of repetition; therefore, this feature is suitable for testing the adaptive convergence suggested by form-environment correlations. Phrynocephalus mystaceus mainly lives in dune habitats, has a developed bilateral toe fringe, and exhibits fast sand-burying behavior for predator avoidance. We tested the effects of resecting the medial and bilateral toe fringes on the locomotor performance and sand-burying performance of P. mystaceus. The results showed that the maximum sprint speed and acceleration on sand substrate did not significantly differ under different conditions (P > 0.05). Sand-burying performance scores of the unresected individuals were significantly greater than those of the resected individuals (P < 0.05). A partial least squares (PLS) regression analysis showed that the relative area of toe fringe was the main factor affecting the sand-burying performance of unresected P. mystaceus. For lizards without fringe, the PLS regression showed that the swinging index of the hind-limb was the main factor affecting the sand-burying performance of the lizard. A comparison of the swinging indexes of the hind-limb of the lizard under three states revealed that under the unresected states, the frequency of the swinging of the hind-limb was significantly higher than those of lizards with resected bilateral fringes, further indicating that the lizards compensated for the loss of fringe by increasing the time and frequency of swinging of the hind-limb. A path analysis also showed that the fringe affected the sand-burying performance of P. mystaceus not only directly but also indirectly by affecting the frequency of the swinging of the hind-limb. After the bilateral toe fringe was removed, a significant negative correlation between locomotor and sand-burying performance was observed (P < 0.05). Taken together, these results provide experimental evidence that toe fringe is positively associated with the sand-burying performance of P. mystaceus.

MONITORING THE TOXICITY OF DRY WOOD TERMITES USING THREE PLANT POWDERS IN LABORATORY CULTURE

In order to model a suitable control alternative for subterranean termites and termites infesting wooden furniture and cabinets where consumables are likely stored, this present study monitored the efficacy of three plant powders at different doses (0.50-1.50g) against the dry wood termite,Cryptotermes cavifrons Banks (Blattodea). Plant materials were locally prepared into powders and assigned to 20 wood termites in 5g substrates of sand and stick. The culture was set up in triplicates and lethal concentrations were determined by Probit analysis. The plant powder could not exerted 100% mortality, but the highest mortality was recorded in Dennettia tripetala (1.50g) on stick (mean= 8.33±0.80). All concentration of D. tripetala on sand and stick caused mortality within 0 to 48 hours after exposure and compared favorably with Permethrin which recorded the highest mean time mortality on sand at 0-24 hrs after exposure. The lowest LC50value (0.75 and 0.79g/g) corresponded to Permethrin and D. tripetala on sand and stick respectively. This results suggest that best concentrations of pepper fruit powder can be adopted as potential alternative to chemical powders.

ANALYSIS OF SEA TURTLE NESTING AREA IN PANDAN ISLAND WEST SUMATRA

The research was conducted on February – March 2020 and located in Pandan Island with using survey method. The research aimed to analyze characteristic habitat of the physical and biological turtle nesting beaches, the distribution of turtle’s nests, and the microbial conditions of the turtle’s nests. The result showed that the length of beach was 1,379.4 m with average width of beach was 16.13 m. The average beach slope was 5.52 %. Substrate type dominated by sand substrate. The most abundant vegetation was ketapang tree (Terminalia catappa) and the predators discovered were monitor lizard and dog. There where 4 turtle nests were found, which was 3 nests of hawksbill turtles and 1 nest of green turtle. The average distance of nests from high tide line was 5.7 m with average distance between nest was 177.87 m. Respectively, the average of temperature, humidity, and depth of the nests were 29.58℃, 12.78%, and 53.3 cm. The average size of curve carapace length was 84.25 cm and average curve carapace width was 76.25 cm. The average number of eggs was 144 of each nest with average diameter of eggs was 3.35 cm.

TEMPERATURAS E SUBSTRATOS PARA O TESTE DE GERMINAÇÃO DE SEMENTES DE Cassia leptophylla Vogel

O teste de germinação é o principal parâmetro de avaliação da qualidade fisiológica de sementes. Entretanto, para a maioria das espécies florestais nativas ainda há uma grande falta de informação sobre a condução do teste de germinação, o que dificulta a elaboração de protocolos para avaliação da qualidade fisiológica. Diante disso, o objetivo do trabalho foi avaliar diferentes temperaturas e substrato para a realização do teste de germinação de sementes de Cassia leptophylla. O delineamento experimental utilizado foi inteiramente casualizado, em arranjo fatorial 4x4, sendo quatro substratos (areia, papel mata borrão, papel toalha e vermiculita) e quatro temperaturas (20, 25, 30 e 20-30 ºC) com quatro repetições de 50 sementes. As variáveis analisadas foram: plântulas normais, primeira contagem de germinação, índice de velocidade de germinação e tempo médio de germinação. A temperatura constante de 30 ºC em substrato areia e a temperatura alternada 20-30 ºC em substrato papel toalha são as condições que favorecem a porcentagem e velocidade de germinação, sendo indicadas para a condução do teste de germinação de C. leptophylla.

Antioxidant Activity and Flavonoid Contents of Daun Dewa (Gynura pseudochina) in Various Substrates with Humic Acid Treatment

Daun dewa (Gynura pseudochina) is a potential producer of a medicinally active compound. Several active compounds contained were steroid, saponin, flavonoid, tannin, and essential oils. The benefit of G. pseudochina as medicine includes anticoagulant (prevent blood clot) and blood liquefaction. The use of zeolite and sand as substrates in this study shall give information about the active compound in the plant. Thus, the objectives of this study were to know the effect of substrate towards the active compound and flavonoid contents, also to determine the effective substrate that leads to the higher activity of antioxidant and flavonoid contents in G. pseudochina. This study used an experimental method with a two-factor factorial, completely randomized design. The first factor was substrates, consist of zeolite and sand substrates. The second factor was the treatment of humic acid concentrations, 0 g/kg; 4g/kg; 8 g/kg; 12g/kg. There were a total of 24 units of experiment, which consist of 8 combinations of treatments with three replications each. The result showed that both zeolite and sand substrates affected the growth and antioxidant activity of G. pseudochina. Zeolite substrate enhanced the antioxidant activity, yet it did not increase the growth. Meanwhile, the sand substrate increased growth. The treatment of 8 g/kg humic acid in a zeolite substrate enhanced the antioxidant activity. The treatment of humic acid in both zeolite and sand substrates could be used to improve the growth and antioxidant activity in G. pseudochina.

Species Richness and Longitudinal Distribution of Macrobenthos at River Pelus in Banyumas

There was a degraded ecosystem and an affected decreasing nekton and microbenthos at River Pelus. So far, no publication of macrobenthos is available. The research purpose was to map species richness and longitudinal distribution of macrobenthos. The survey method was taken with stratified random sampling in eight stations and five replicates from May to July 2018. The result showed ten species of macrobenthos. All species belonged to class Malacostraca (four species) and Gastropoda (six species). Of the four species collected in all replicates, Macrobrachium oenone categorized as an indicator species that only lived in Station II because there were a boulder substrate and good water quality. In the same class, M. pilimanus, Parathelpusa bogoriensis, and P. convexa were in all stations except station V because there was a sand substrate and poor water quality. In station V, there were only two species of gastropod, Melanoides riquerti and Pomacea canaliculata that could live. In general, there were a cosmopolitan species that could live in all substrates and water quality such asM. riquerti. For a longitudinal distribution map, there was a unique tendency of decreasing species richness numbers due to the river weir.

Collision of Shaped Boulders With Sand Substrate Investigated by Experimental, Stochastic, and Discrete Approaches

This paper focuses on experimental and numerical studies aiming to better characterize the rebound kinematics between a natural soil and rock boulders using single‐block collision models. The variability of the dissipative parameters needed to reproduce the experimental results was studied considering two different approaches: stochastic transfer matrix and discrete element model (DEM). An experimental process taking into account all possible variables related to the collision was setup for small‐scale tests involving cylindrical and triangular boulders that introduces natural variability during impact. The objective of the experimental tests is to identify the relationship between incident and reflected velocities (before and after impact, respectively), in order to improve the predictability of the two numerical proposed approaches. The experimental results help to quantify the amount of energy losses during impacts and thus expands the knowledge to reproduce more realistic rockfall events. This work is divided in three main axes: (i) statistical analysis of experimental trajectories based on experimental tests; (ii) stochastic approach predicting in a simple way from initial velocities the kinematic of blocks after rebounds; and (iii) calibration of a discrete element model including probabilistic analysis based on Monte Carlo approach. This way, the two collision approaches presented in this work are able to predict rebounds in terms of averages, standard deviations, and distributions.

The effects of rubble mobilisation on coral fragment survival, partial mortality and growth

The sliding and overturning of unconsolidated rubble by hydrodynamic forcing is expected to cause physical damage to settled coral recruits and asexual fragments by scouring and smothering. Yet, few empirical studies have tested the relationship between rubble mobilisation frequency and the survival and growth of these corals. Here, we tested the response of small coral fragments to varying levels of experimental scouring and smothering, proxies for rubble mobilisation impacts, on two coral species with distinct functional traits; Porites rus (robust, encrusting) and Pocillopora verrucosa (sensitive, branching). This study investigated: 1) how coral fragment survival was affected by inversion on rubble or sand substratum over ~2 w (i.e. smothering); and 2) how the survival, growth and tissue properties of fragments were affected by rubble being overturned (i.e. experiencing scouring or abrasion) at different frequencies over ~10 w. Smothering substratum had a profound influence on the probability of fragment survival. For both species, survival was <2% after 5 d when inverted on sand, whereas nearly all survived when inverted on rubble. Following scouring, most P. rus fragments survived over the ~10-w period irrespective of scour frequency. However, P. verrucosa showed high mortality (45% loss) across all treatments, likely influenced by initial handling and fragmentation. For P. rus, increasing scour frequency caused sublethal effects of significantly reduced tissue growth and pigmentation, and increased partial mortality. These findings indicate that small fragments – and potentially recruits – are unlikely to successfully recruit in frequently-mobilised rubble beds regardless of their functional morphotype, but may persist in rubble beds in lower-energy environments. This provides valuable insight into the limitations on coral recovery in rubble beds, which could inform reef recovery programs considering substratum stabilisation. Combined with an understanding of a reef's hydrodynamic environment, this research can assist managers in prioritising damaged reefs for active interventions.

Multiple Estuarine Gradients Influencing Tidal Flat Benthic Algal Biomass and Community Structure in the Yaquina Estuary, OR, USA

Tidal flat is often the dominant habitat type in US Pacific Northwest (PNW) estuaries. This research examined environmental factors that explain the spatial patterns of microphytobenthos (MPB) biomass and community structure in a PNW estuary with complex nutrient dynamics. MPB biomass, individual species abundances, diatom community metrics, and diatom community structure were strongly correlated with distance from the estuary mouth, salinity, substrate composition, and pore water-soluble reactive phosphorus (SRP). The microphytobenthos was dominated by diatoms and diatom diversity and species richness were negatively associated with salinity, substrate sand content, and pore water SRP. Diatom community structure varied with estuary position, with the epipsammic taxa Catenula adhaerens, Opephora spp. 1, and Planothidium delicatulum dominating the assemblage at sites near the estuary mouth and epipelic taxa, such as Nitzschia frustulum and Nitzschia palea, being more abundant at sites in the middle and upper estuary. Distance from the estuary mouth and salinity were the most important predictors of diatom assemblage structure, based on CCA analysis. MPB biomass was highest at sites in the lower estuary, characterized by higher salinities, SRP, and substrate sand composition. Pore water nitrogen and surrounding land use were not important predictors of MPB biomass or community structure. We attribute our findings to the nutrient dynamics of Yaquina estuary, which is high in nutrients due to both coastal upwelling and watershed-derived nitrate and exhibits an increasing gradient of phosphorus towards the estuary mouth.