Periods Of Submersion Research Articles

Experimental insights on biofouling growth in marine renewable structures.

Marine biofouling is a threat to industries working in the marine environment, representing significant costs associated with equipment impairment and loss of performance. In the Marine Renewable Energy (MRE) and other maritime sectors which operate at sea for long periods, an important aspect of biofouling is related to the type and frequency of inspections and biofouling removal procedures. This study investigated important parameters of macrofouling ( e.g. composition, including the presence of non-indigenous species, thickness, and weight) from communities growing on samples that emulate tubular components of marine renewable devices. The trials were performed during short periods of submersion (one to eight weeks) in the seasons when the colonisation process should be most intensive (spring, summer, and autumn). Furthermore, the frictional resistance forces generated during the scraping of biofouling from those components were investigated. Overall, results provide insights on the growth rates and removal requirements of biofouling in marine components. The results show that, while biofouling growth in early colonization stages might not present great detrimental effects to wave energy components, the consequent marine corrosion (fostered by biofouling) and the settlement of non-indigenous species (NIS) should be factors of concern. Performing biofouling-related maintenance activities after the peak of maximum growth and reproduction (during the warmer seasons in temperate to cold environments) is suggested to reduce the number and frequency of activities. NIS can be detected at very early stages in the colonization process, highlighting the importance of biofouling monitoring and the implementation of biosecurity risk assessment plans early in the operational stage of MRE projects.

Individual architecture and photosynthetic performance of the submerged form of Drosera intermedia Hayne

Drosera intermedia grows in acidic bogs in parts of valleys that are flooded in winter, and that often dry out in summer. It is also described as the sundew of the most heavily hydrated habitats in peatlands, and it is often found in water and even underwater. This sundew is the only one that can tolerate long periods of submersion, and more importantly produces a typical submerged form that can live in such conditions for many years. Submerged habitats are occupied by D. intermedia relatively frequently. The aim of the study was to determine the environmental conditions and architecture of individuals in the submerged form of D. intermedia. The features of the morphological and anatomical structure and chlorophyll a fluorescence of this form that were measured were compared with analogous ones in individuals that occurred in emerged and peatland habitats. The submerged form occurred to a depth of 20 cm. Compared to the other forms, its habitat had the highest pH (4.71–4.92; Me = 4.71), the highest temperature and substrate hydration, and above all, the lowest photosynthetically active radiation (PAR; 20.4–59.4%). This form differed from the other forms in almost all of the features of the plant’s architecture. It is particularly noteworthy that it had the largest main axis height among all of the forms, which exceeded 18 cm. The number of living leaves in a rosette was notable (18.1 ± 8.1), while the number of dead leaves was very low (6.9 ± 3.8). The most significant differences were in the shape of its submerged leaves, in which the length of the leaf blade was the lowest of all of the forms (0.493 ± 0.15 mm; p < 0.001) and usually the widest. The stem cross-sectional area was noticeably smaller in the submerged form than in the other forms, the xylem was less developed and collaterally closed vascular bundles occurred. Our analysis of the parameters of chlorophyll fluorescence in vivo revealed that the maximum quantum yield of the primary photochemistry of photosystem II is the highest for the submerged form (Me = 0.681), the same as the maximum quantum yield of the electron transport (Me φE0 = 0.183). The efficiency of energy use per one active reaction center of photosystem II (RC) was the lowest in the submerged form (Me = 2.978), same as the fraction of energy trapped by one active RC (Me = 1.976) and the non-photochemical energy dissipation (DI0/RC; Me = 0.916). The ET0/RC parameter, associated with the efficiency of the energy utilization for electron transport by one RC, in the submerged plant reached the highest value (Me = 0.489). The submerged form of D. intermedia clearly differed from the emerged and peatland forms in its plant architecture. The submerged plants had a thinner leaf blade and less developed xylem than the other forms, however, their stems were much longer. The relatively high photosynthetic efficiency of the submerged forms suggests that most of the trapped energy is utilized to drive photosynthesis with a minimum energy loss, which may be a mechanism to compensate for the relatively small size of the leaf blade.

Use of passive sampling in environmental DNA metabarcoding technology: Monitoring of fish diversity in the Jiangmen coastal waters

Environmental DNA (eDNA) metabarcoding technology is proving to be the most up-to-date and promising method for monitoring marine fish diversity. Fish eDNA is usually collected on a filter membrane after the filtration of water. Not only does this require the use of specialized equipment, but the amount of filtered water needed is also difficult to meet. The recently proposed passive eDNA collection method can expand the sampling scale, providing new perspectives for monitoring marine biodiversity. The role of collection methods in eDNA surveys, however, remains unclear. In this study, a low-cost custom framework with two types of filter membrane materials was used to conduct passive submersion samplings at the north and south ends of Shangchuan Island, Jiangmen, China. After defined periods of submersion, the filter membranes were recovered and eDNA extracted. Metabarcoding techniques were applied to detect fish species information in the eDNA samples. A total of 106 marine fish species from 27 orders, 53 families, and 92 genera, including one cartilaginous fish, were identified in the samples. The majority of fish detected by active filtration were also found in the passively collected samples, within the same location. Both sampling methods, therefore, showed similar species richness. Passive sampling was effective in identifying fish species diversity and provided a higher spatial resolution owing to the sample replicates. Passive sampling was also more sensitive in detecting species that differ significantly in abundance (biomarkers) between different sampling depths. When active filtration is not possible, or when large-scale sampling is the purpose of the study, passive sampling methods certainly provide a promising alternative. The findings of our study provide guidance for fish surveys and continuous bio-stereoscopic monitoring in coastal waters.

An opinion on BlueCAM an Australian blue carbon method to estimate climate change mitigation benefits of coastal wetland restoration by Lovelock et al. (2022)

BlueCAM is an Australian coastal wetland restoration methodology for estimating atmospheric warming abatement. However, BlueCAM is incomplete and contains conceptual and formulation errors. Conceptually, sequestration may be understated by not accounting for an increase in animal biomass and baseline ecosystems as heterotrophic carbon sources. Or, more likely, sequestration services are significantly overestimated by not considering: (1) remineralization of allochthonous carbon, supplied from surrounding ecosystems; (2) the subtraction of a notable intrinsically recalcitrant allochthonous carbon fraction; (3) whether baseline ecosystems are autotrophic carbon sinks; and (4) the reduction in air–sea flux during periods of submersion. Erroneously, BlueCAM: (1) implies that any remains of labile allochthonous carbon should be subtracted from stocks, not just the recalcitrant fraction; and (2) does not embed additional warming from CH4 emissions within components of net ecosystem production. Taken together, these errors are likely to greatly overestimate both wetland sequestration and warming abatement services.

Mechanical control inadvertently increases risk of alien plant invasion: influence of stem fragmentation and inundation regimes on Arundo donax regeneration in Neotropical savanna

Context Arundo donax L. is an exotic, perennial grass that has invaded dryland and wetland savannas of central Brazil. This species produces sterile flowers in its introduced range and propagates vegetatively via rhizomes and stem fragments. Aims We investigated bud sprouting capacity after fragmentation, which plays a major role in plant-proliferation ability, invasiveness and its escape from weed-control measures. Methods We evaluated the effects of size, different periods of desiccation (by exposure to air), submersion and water-column height on the regenerative capacity of single-node stem fragments. Key results Fragments of a minimum size of 3–4 cm successfully regenerated new plants. The regenerative capacity of single-node stem fragments (3–10 cm length) rapidly decreased after 1 week of air desiccation. Stem fragments that were submerged for 30 days resprouted and formed plants in a water column of 5, 10 or 15 cm, with no significant difference from the controls. However, leaves did not expand and shoot elongation was adversely affected in 15 cm of non-aerated water. This loss of performance was reversed when the newly formed plants were removed from the water and transferred to a moist substrate. Implications Our findings suggest that weed management, which involves cutting the plant to ground level without removing it from the site, is inefficient and can intensify the potential for invasion by A. donax, especially in the rainy season, when left-over stem fragments remain hydrated and capable of regeneration. Its establishment near riverbanks must be monitored because submerged propagules remain viable and able to resprout.

Early biofouling colonization stages: Implications for operation and maintenance planning in marine renewable energy projects

Background:Marine biofouling is a threat to industries working in the marine environment, representing enormous costs associated with equipment impairment and loss of performance. In the Marine Renewable Energy (MRE) and other maritime sectors which operate at sea for long periods, an important aspect of biofouling is related to the type and frequency of maintenance.Methods:This study investigated important parameters of macrofouling (for example composition, including the presence of non-indigenous species, thickness, and weight) from communities growing on small-scale wave energy components in marine conditions. The trials were performed during short periods of submersion (one to eight weeks) in the seasons when the colonisation process should be most intensive (spring, summer, and autumn). Furthermore, the frictional resistance forces generated to scrape the biofouling from those artificial components were investigated.Results:Overall, results show that while biofouling growth in early colonization stages might not present great detrimental effects to wave energy components, although marine corrosion and the settlement of non-indigenous species (NIS) should be factors of concern.Conclusions: It is suggested to perform biofouling-related maintenance activities after the peak of maximum growth and reproduction (during the warmer seasons in temperate to cold environments) to reduce the number and frequency of activities. NIS can be detected very early in the colonization process, highlighting the importance of biofouling monitoring and the implementation of biosecurity risk assessment plans early in the operational stage of MRE projects.

Marine environment induced failure of FRP composites used in maritime transport

Fiber reinforced polymer (FRP) composites are being extensively considered for construction of ships and marine structures. Due to harsh environmental operational conditions, failure prediction of such structures is an imperative in this industry sector. This paper presents the final results of a 2-year research of real marine environment induced changes of mechanical properties in FRP composites.Realistic environmental input parameters for structural modeling of marine structures are crucial and can be obtained by conducting tests in real sea environment for prolonged periods, as opposed to usual accelerated laboratory experiments. In this research, samples of epoxy/glass and polyester/glass with various fiber layout configurations have been submerged under the sea for periods of 6, 12 and 24 months. An analysis of mass changes, marine microbiology growth, tensile strength and morphological structures of the coupons was performed and compared with samples exposed to room environment.All samples exhibited an increase in mass due to seawater absorption and microorganism growth in the organic resins (matrix). The tensile strength loss variation through the periods of submersion showed a correlation with the fiber layout configuration. The results of optical and scanning electron microscopical investigation indicated significant matrix morphological changes primarily due to salt crystal formation and the impact of sea microorganisms embedding in and attaching to the resin.The outcome of this research will be the basis for a set of realistic input parameters for a failure analysis numerical tool currently in development that can be applied for life-time behavior predictions of marine structures.

Effect of Time-Real Marine Environment Exposure on the Mechanical Behavior of FRP Composites

Fiber reinforced polymer (FRP) composites coupons were exposed to real sea environment to assess the influence on the mechanical behavior of composite materials used in the construction of marine structures. Real-life sea environment conditions were opted for instead of the more common simulated and laboratory versions of seawater in the attempt to obtain more realistic structural modeling environmental input design parameters for marine structures. Exposure was performed over prolonged time span instead of the usual accelerated tests. Epoxy and polyester resins, reinforced with glass fibers in three fiber layout configurations, were used to manufacture standardized tensile testing coupons. Mass changes due to seawater absorption, microorganism growth, changes in tensile strength (standard tensile tests), and surface morphology of the coupons were evaluated after 6- and 12-month long periods of submersion in the sea in the Rijeka bay, Croatia. All specimens showed mass increase due to water absorption and growth of attached algae and sea microorganisms. Various levels of reduction in tensile strength, depending on the fiber layout configurations, were observed. Significant changes in the matrix material structure were noticed, effectively producing “voids”. Based on these results, sustainability of FRP composites in marine environment is addressed and discussed.

Survival strategies on a semi-arid island: submersion and desiccation tolerances of fiddler crabs from the Galapagos Archipelago

During tidal cycles, fiddler crabs undergo alternating periods of submersion and desiccation. We compare physiological and biochemical adjustments to submersion and desiccation challenge in two gelasminids from the Galapagos archipelago: the indigenous Leptuca helleri, and Minuca galapagensis. We examine population distributions and habitat characteristics; survival and hemolymph osmolality after 6 h submersion at several salinities, and after 6 or 12 h desiccation; and oxidative stress responses in the hepatopancreas and gills, accompanying glutathione enzyme antioxidant activities, and lipid peroxidation. We provide an integrated biomarker response index based on oxidative stress in each tissue, condition and species. Leptuca helleri occupies a restricted intertidal niche while M. galapagensis is supralittoral. Burrow density in M. galapagensis declined with increasing salinity and decreasing substrate moisture; L. helleri burrow density showed no correlation. After 6 h submersion, L. helleri survived only at 21‰S while M. galapagensis survived from 0 to 42 ‰S. After 6 h desiccation, hemolymph osmolality decreased markedly in L. helleri but increased in M. galapagensis. Antioxidant enzyme activities and lipid peroxidation in the hepatopancreas and gills showed tissue- and species-specific responses to submersion and desiccation challenge. The integrated biomarker response indexes for L. helleri were highest in control crabs, driven by oxidative stress. In M. galapagensis, submersion was the determining factor in both tissues. Minuca galapagensis is a generalist species while Leptuca helleri occupies a more restricted intertidal habitat. The species’ respective physiological limitations and flexibilities provide insights into how fiddler crabs might respond to environmental change on semi-arid islands.

Antioxidant Activity of Dictyotales from Tropical Reefs of Brazil.

Macroalgae produce a large range of primary and secondary metabolites with ecological and economical importance. Studies on antioxidants from marine algae have increased notably, focusing on searching new sources of natural compounds for different applications, in which tropical species have been shown to have high potential, often improved by stressful environmental conditions during the tide cycle with periods of emersion and submersion. Therefore, in order to characterize the antioxidant activity and relate it to local environmental tide exposure, three species of brown marine algae, Canistrocarpus cervicornis, Dictyopteris delicatula, and Lobophora variegata from two beaches on the northeast coast of Brazil were studied. Dichloromethane:methanol (DCM:M) and aqueous extracts were tested for ferric reducing antioxidant power, 2,2-diphenyl-1-picrylhydrazyl, and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) antioxidant assays and total phenolic compounds. Aqueous extracts of C. cervicornis showed up to 10 times major antioxidant activity and phenolic compounds than DCM:M extracts. Different characteristic of antioxidant activity were identified among the beaches, species, and extracts, in which aqueous extracts from C. cervicornis and L. variegata showed the most promising matrices for future prospection of natural antioxidants.

Air-entrapping capacity in the hair coverage of Malacosoma castrensis (Lasiocampidae: Lepidoptera) caterpillar: a case study.

The moth Malacosoma castrensis (Lasiocampidae) is commonly found along the Northern Germany coasts, the habitats of which are mainly represented by salt marshes subjected to sea level variations. Surprisingly, terrestrial caterpillars can withstand many hours of being flooded by seawater. The ability to withstand periods of submersion in a terrestrial insect raises the problem of respiration related to avoiding water percolation into the tracheal system. In the present study, we investigated under laboratory conditions the role of water-repellent cuticle structures in oxygen supply in caterpillars of M. castrensis submerged in water. For this purpose, air-layer stability tests using force measurements, and micromorphology of cuticle structures using SEM and fluorescence microscopy, were performed. A plastron appeared when a caterpillar is underwater. The stability, gas composition and internal pressure of the plastron were estimated. The plastron is stabilized by long and scarce hairs, which are much thicker than the corresponding hairs of aquatic insects. Thick and stiff hairs with sclerotized basal and middle regions protrude into the water through the plastron-water interface, while substantial regions of thin and flexible hairs are aligned along the plastron-water interface and their side walls can support pressure in the plastron even below atmospheric pressure. Additional anchoring points between hair's stalk and microtrichia near the hair base provide enhanced stiffness to the hair layer and prevent the hair layer from collapse and water entering between hairs. The advancing contact angle on hairs is more than 90deg, which is close to the effective contact angle for the whole caterpillar.

Seismic evidence of glacial-age river incision into the Tahaa barrier reef, French Polynesia

Rivers have long been recognized for their ability to shape reef-bound volcanic islands. On the time-scale of glacial–interglacial sea-level cycles, fluvial incision of exposed barrier reef lagoons may compete with constructional coral growth to shape the coastal geomorphology of ocean islands. However, overprinting of Pleistocene landscapes by Holocene erosion or sedimentation has largely obscured the role lowstand river incision may have played in developing the deep lagoons typical of modern barrier reefs. Here we use high-resolution seismic imagery and core stratigraphy to examine how erosion and/or deposition by upland drainage networks has shaped coastal morphology on Tahaa, a barrier reef-bound island located along the Society Islands hotspot chain in French Polynesia. At Tahaa, we find that many channels, incised into the lagoon floor during Pleistocene sea-level lowstands, are located near the mouths of upstream terrestrial drainages. Steeper antecedent topography appears to have enhanced lowstand fluvial erosion along Tahaa's southwestern coast and maintained a deep pass. During highstands, upland drainages appear to contribute little sediment to refilling accommodation space in the lagoon. Rather, the flushing of fine carbonate sediment out of incised fluvial channels by storms and currents appears to have limited lagoonal infilling and further reinforced development of deep barrier reef lagoons during periods of highstand submersion.

Assessment of the Risk of Fractures Because of Service on Diesel Submarines: A Retrospective Cohort Study.

Submariners are known to have decreased bone mass following periods of long submersion. We examined whether this produces a higher predilection to fractures. This is a retrospective cohort study. Data were collected from the computerized medical records of 457 consecutive submariners (serving 1091.42 man-years). The control group included 3,219 consecutive sailors, (serving 5845.04 man-years). Groups were stratified according to age at induction, body mass index, place of birth, and status of service (i.e., compulsory versus professional). Analysis of fracture incidence and comparison of proportions between the groups was conducted using χ(2) tests and Fisher's exact test. The hazard ratio for fractures was performed using a survival analysis regression model for each group (Cox Proportional Hazard Model). Nineteen submariners (4.2%) and 94 sailors (2.9%) were shown to have fractures during their service (RR = 1.42, p = 0.15). A Cox proportional hazard model was employed. No statistically significant difference was found between the 2 groups (HR = 1.037, p = 0.89). No correlation was found between length of service and risk of fracture. Most fractures suffered by submariners occurred outside their work environment. Submariners are repeatedly exposed to prolonged submersions that are deleterious to bone strength. However, no statistically significant difference in the incidence of fractures was found between submariners and surface sailors. This is an important finding for the bone and occupational health of submariners in general.

Submersion tolerance in a lakeshore population ofPardosa lapidicina(Araneae: Lycosidae)

Terrestrial animals often inhabit stochastic boundaries between terrestrial and aquatic habitats which are under constant risk of flooding. In these circumstances, terrestrial arthropods often exhibit behavioral and physiological adaptations to cope with this risk by either avoiding flooding or tolerating submersion. We present the results of a study designed to explore submersion tolerance in a lakeshore population of Pardosa lapidicina (Emerton 1885), a eurytopic lycosid. Spiders were submerged in lake water for 4, 8, 11, or 16 hours, then removed and tested for responsiveness. Each spider was checked for responsiveness a second time after an eight-hour period in a dry vial. Spiders that were submerged for longer periods were less likely to be responsive immediately after removal. However, between 7% and 38% additional spiders resumed activity eight hours after removal, their recovery depending on their time submerged. This suggests that adult P. lapidicina can survive long periods of submersion in a quiescent state and later resume activity.

Influence of the Three Gorges Reservoir on the Vegetation of Its Drawdown Area: Effects of Water Submersion and Temperature on Seed Germination ofXanthium sibiricum(Compositae)

ABSTRACT: Xanthium sibiricum, an annual weed, unexpectedly and dramatically occupied the exposed drawdown area after water had been impounded for the first time in the newly created Three Gorges Reservoir in China. In order to explain this phenomenon and establish an appropriate management strategy, the effects of constant submersion on seed viability and germination of X. sibiricum were investigated at two constant temperature regimes (25°C and 30°C) under artificial laboratory conditions. The results indicated that the seeds of X. sibiricum exhibited a high level of tolerance of submersion and up to 99% of seeds were viable in each treatment regime. The effect of submersion on germination was not obvious at 25°C until the submersion was prolonged for 180 days, while at 30°C the eventual germination rate of X. sibiricum, even after submergence for only one day, was significantly improved. The speed of germination was also consistently accelerated by prolonged periods of submersion. The proportion of seed...

Differential nutrient uptake by two segregated red algae in an estuarine intertidal zone

SÁnchez de Pedro R., Niell F.X. and Carmona R. 2013. Differential nutrient uptake by two segregated red algae in an estuarine intertidal zone. Phycologia 52: 461–471. DOI: 10.2216/13-147.1Bostrychia scorpioides (Rhodophyta: Ceramiales) and Catenella caespitosa (Rhodophyta: Gigartinales) were segregated but slightly overlapping in the narrow intertidal of the Palmones River Estuary (Southern Spain). This study investigated whether there were interspecific differences in nutrient uptake capabilities and how meaningful these were to zonation. Uptake kinetics of ammonium, nitrate, and phosphate were measured over successive time intervals across a range of environmentally realistic concentrations. The interactions between ammonium and nitrate in mixed N source uptake were also tested. Using internal N and P content, turnover rates were calculated for each species for periods of emersion and submersion. Nutrient uptake kinetics were saturable for almost all nutrients except for ammonium in B. scorpioides, which showed surge uptake responses through linear kinetics. Vmax and affinity progressively decreased over 3 h for all nutrients in C. caespitosa and only for phosphate in B. scorpioides. At high dissolved inorganic nitrogen concentrations both species exhibited greater uptake rates for ammonium than nitrate; although, similar N uptake rates were obtained at the low ones. Ammonium contributed to the total N uptake in B. scorpioides to a greater extent; whereas, in C. caespitosa, this only occurred at high N concentrations. In mixed N source uptake experiments, ammonium and nitrate uptake rates by B. scorpioides decreased when the other N source was equimolarly supplied, while in C. caespitosa these interactions were absent. Catenella caespitosa showed a Vmax and affinity for phosphate fourfold higher than for B. scorpioides, with greater interspecific differences than those found for N uptake. Catenella caespitosa renewed internal nutrients faster and was more dependent on the external nutrient supply than B. scorpioides, which can withstand longer periods without nutrient supply due to its slower nutrient turnover rate. Different capabilities for nutrient acquisition in the two species suggested an adaptation to the nutrient availability at each intertidal position.

Tenderize Chicken Breast Meat by Using Different Methods of Curing

The aim of this study is tenderizing breast spent hens meat by using cheap local materials such us (bitter orange juice, vinegar, salt and sugar for (1, 2 and 3) h, distill water is used (T ) in curing to make 1 it as standard. Bitter orange juice (acidity of 1.5) (T ), vinegar (acidity of 7) (T ), table salt (2%) (T ) and sugar 2 3 4 (2%) (T ) were used. The processed meat was investigate the influence of the type of treatment and the 5 periods of storing and submersion on the sensory properties and chemical qualities through estimating the percentage of moisture, volume of the released extract. A sensory properties evaluation of the qualities of flavor, juiciness, tenderness and overall acceptance was carried out. The following findings were obtained: The percentage of moisture increased significantly (p<0.05) of the treatment groups compared with T. It was 1 found that the highest significant differences (p<0.05) was T. A decrease appeared in the volume of the 4 released extract. The highest significant (p<0.05) was T and the lowest one was T. Results of 1 4 sensory evaluation indicated the improvement of the sensory qualities of the samples treated with the different solutions especially of tenderness and juiciness. These results were reflected on the quality of general acceptance by the consumer of the samples. Results of sensory evaluation revealed that T and T 2 4 was the best sample. Significant differences (p<0.05) as far as the periods of curing were noticed. Thus we can recommend using 2% salt and bitter orange juice (1.5 acidity) in curing breast spent hens meat.

A precise water displacement method for estimating egg volume

Relationships between egg volume and an array of life-history traits have been identified for many bird species. Despite the importance of egg volume and the need for precise and accurate measurements, egg volume is usually estimated using a mathematical model that incorporates length and width measurements along with a shape variable. We developed an instrument that provides precise estimates of egg volume and can be easily used in the field. Using Clapper Rail {Rallus longirostris) eggs, we compared egg volumes measured using our instrument with estimates based on linear measurements. We found our instrument to be both precise and accurate. Compared with a method based on linear measurements of eggs, use of our instrument reduced variation in egg volume estimates by 1.6 cm3, approximately 8% of the volume of a Clapper Rail's egg. Further advantages of our technique include ease of use, increased accuracy of field-based volume estimates, and increased resolution of variation in egg volume estimates. In addition, our technique does not require postdata collection processing time and did not influence hatching success. Also, for Clapper Rails and similar species, our technique can be combined with other techniques (e.g., egg flotation) so that both egg volume and embryonic stage can be estimated at the same time.

Effects of waterlogging on seed germination of three Mediterranean oak species: Ecological implications

Soil water saturation during prolonged periods of time generates a negative impact on nearly all terrestrial plants. In Mediterranean woodlands, precipitation can be very abundant during the wet season, inducing temporary soil waterlogging, coinciding with the seed dispersal and germination time of many species. We investigated the effects of waterlogging on seed germination and early root growth of three coexisting oak species ( Quercus canariensis, Q. suber and Q. pyrenaica), by completely flooding of seeds for various periods of time. The three oak species showed a certain level of tolerance to waterlogging, only being affected those seeds subjected for long periods of submersion (over 30 days). Waterlogging during prolonged periods of time decreased the probability of seed germination in the three oak species, lengthened the time to germination, and hampered root development in two of the studied species. The main differences between oak species occurred in terms of root growth ( Q. canariensis being the less affected, and Q. suber the most); these differential responses could be related to a species rank of waterlogging tolerance. Thus inter-specific differences in germination responses to waterlogging could contribute to explain, at least partially, species habitat and distribution patterns across landscapes. Seed mass also played an important role on different aspects of germination, though its relative importance varied as function of species and waterlogging treatment. The tolerance to stress induced by waterlogging increased with seed mass, but only in the case of Q. canariensis.

Using Different Methods to Tenderize Spent Hens Meat

The aim of this study is tenderizing spent hens meat by using cheap local materials such as bitter orange juice, vinegar, salt and sugar for 1,2, 3 and 4h, distill water is used (T ) in curing to make it a s 1 standard. Bitter orange juice (acidity of 1.5) (T ), vinegar (acidity of 7) (T ), table salt (2%) (T ) and sugar (2%) 2 3 4 (T ) were used. The processed meat was storied under -18 C ± 2 C for a month to investigate the influence 5 o o of the type of treatment and the periods of storing and submersion on the sensory properties and chemical qualities through estimating the percentage of moisture, hydrogen number pH, volume of the released extract. A sensory properties evaluation of the qualities of flavor, juiciness, tenderness and overall acceptance was carried out. Results of curing in the different solutions revealed a decreased pH value in (T ) 2 and T ; while the highest significant differences (p<0.05) was in samples T. Besides, there were no 3 4 significant differences concerning the periods of curing. As far as the period of freezing is concerned, a significant increase in pH of the samples was noticed, T had the upper degree. There were no significant 4 differences concerning the periods of curing. The percentage of moisture increased significantly (p<0.05) of the treatment groups compared with T. The highest significant differences (p<0.05) were found in T. A 1 4 significant (p<0.05) increase occurred in the percentage of moisture when it was frozen and cured. Besides, there were significant differences (p<0.05) concerning the period of curing. A decrease was noticed of the volume of the released extract. The highest significant (p<0.05) difference was in T and the lowest one was 1 in T. It was also noticed that significant (p<0.05) increase of the frozen sample, the highest significant 4 difference (p<0.05) was in T and the lowest one was in T. Results of sensory evaluation indicated the 1 4 improvement of the sensory qualities of the samples treated with the different solutions especially of tenderness and juiciness. These results were reflected on the quality of general acceptance by th e consumer of the samples. Results of sensory evaluation revealed that T and T was the best sample. 2 4 Significant differences (p<0.05) as far as the periods of curing were noticed. Thus we can recommend using 2% salt and bitter orange juice (1.5 acidity) in curing spent hens meat.