Use of Washington Estuaries by Subadult and Adult Green Sturgeon

Green sturgeon, Acipenser medirostris, are the most marine-oriented of North American sturgeons. However, their estuarine/marine distribution and the seasonality of estuarine use are largely unknown. We used acoustic telemetry to document the timing of green sturgeon use of Washington estuaries. In the summers of 2003 and 2004, uniquely coded acoustic transmitters were surgically implanted in green sturgeon captured using commercial gillnets. All sturgeon tagged were greater than 1.2 m total length. They were caught, tagged, and released in both Willapa Bay (n = 49) and Columbia River (n = 11) estuaries. We deployed an array of four fixed- site acoustic receivers in Willapa Bay to detect the estuarine entry and exit of these and any of over 100 additional green sturgeon tagged in other systems during 2003 and 2004. Green sturgeon occurred in Willapa Bay in summer when estuarine water temperatures exceeded coastal water temperatures by at least 2°C. They exhibited rapid and extensive intra- and inter- estuary movements and green sturgeon from all known spawning populations were detected in Willapa Bay. We hypothesize that green sturgeon optimize their growth potential in summer by foraging in the relatively warm, saline waters of Willapa Bay and we caution that altering the quality of estuarine habitats could negatively affect this species throughout its range.     

Detection of Adult Green Sturgeon Using Environmental DNA Analysis

Environmental DNA (eDNA) is an emerging sampling method that has been used successfully for detection of rare aquatic species. The Identification of sampling tools that are less stressful for target organisms has become increasingly important for rare and endangered species. A decline in abundance of the Southern Distinct Population Segment (DPS) of North American Green Sturgeon located in California’s Central Valley has led to its listing as Threatened under the Federal Endangered Species Act in 2006. While visual surveys of spawning Green Sturgeon in the Central Valley are effective at monitoring fish densities in concentrated pool habitats, results do not scale well to the watershed level, providing limited spatial and temporal context. Unlike most traditional survey methods, environmental DNA analysis provides a relatively quick, inexpensive tool that could efficiently monitor the presence and distribution of aquatic species. We positively identified Green Sturgeon DNA at two locations of known presence in the Sacramento River, proving that eDNA can be effective for monitoring the presence of adult sturgeon. While further study is needed to understand uncertainties of the sampling method, our study represents the first documented detection of Green Sturgeon eDNA, indicating that eDNA analysis could provide a new tool for monitoring Green Sturgeon distribution in the Central Valley, complimenting traditional on-going survey methods.     

Evaluation of Adult White Sturgeon Swimming Capabilities and Applications to Fishway Design

Concern over passage of sturgeon barriers, has focused attention on fishway design that accommodates its swimming performance. In order to evaluate swimming performance, regarding fish ladder type partial barriers, wild adult sturgeons, Acipenser transmontanus; 121–76m fork length, were captured in the San Francisco Bay Estuary and Yolo Bypass toe drain. Hydrodynamic forces and kinematic parameters for swimming performance data were collected in a laboratory flume under three flow conditions through barriers and ramp. The experiments were conducted in a 24.4 m long, 2.1 m wide, and 1.62 m deep aluminum channel. Two geometric configurations of the laboratory model were designed based on channel characteristics that have been identified in natural river systems. At a given swimming speed and fish size, the highest guidance efficiencies of successful white sturgeon passage as a function of flow depth, flow velocity, turbulence intensity, Reynolds number, Froude number and shear velocity observed in the steady flow condition, tested with the horizontal ramp structure, occurred at an approach velocity of 0.33 ms^-1. The guidance efficiency of successful sturgeon passage increased both with increasing flow velocity and Froude number, and decreased both with the flow depth and the turbulence intensity. This study also provides evidence that tail beat frequency increases significantly with swimming speed, but tail beat frequency decreases with fish total length. Stride length increases both with swimming speed and fish total length. The importance of unsteady forces is expressed by the reduced frequency both with swimming speed and fish total length. Regression analysis indicates that swimming kinematic variables are explained by the swimming speed, the reduced frequency and the fish total length. The results emphasize the importance of fish ladder type patchiness when a fishway is designed for the passage of sturgeon.     

A Theoretical Study of River Fragmentation by Dams and its Effects on White Sturgeon Populations

Most of the world's large rivers are fragmented by dams. Fragmentation of the river ecosystem alters migration patterns among fish populations and converts free-flowing river to reservoir habitat. In this study, we used an individual-based genetic metapopulation model to study the effects of fragmentation on the population viability and genetic diversity of a large-river fish, the white sturgeon, Acipenser transmontanus. In the first of two simulation experiments, we fragmented a 200km river reach by building 1 to 20 virtual dams. Increased fragmentation produced an exponential decline in the likelihood of persistence, but no extinction threshold to suggest a minimum viable length of river. Compounding isolation with the loss of free-flowing habitat did not further reduce viability until free-flowing habitat was nearly eliminated, at which point extinction was certain. Genetic diversity within (among) populations decreased (increased) as we built the first several dams. Adding more dams caused the number of persisting populations to decline and eroded genetic diversity within and among populations. Our second simulation experiment evaluated the effects of different levels of upstream and downstream migration between river segments. The results of these migration experiments highlighted the importance of balanced migration rates. We found that extinction risk was high for populations linked by high downstream, and low upstream, migration rates, as is often the case in impounded rivers. Our results support the view that migration patterns will play a significant role in determining the viability of riverine fishes, such as the white sturgeon, in river ecosystems fragmented by dams.(retired)     

Population Status of North American Green Sturgeon, Acipenser medirostris

North American green sturgeon, Acipenser medirostris, was petitioned for listing under the Endangered Species Act (ESA). The two questions that need to be answered when considering an ESA listing are; (1) Is the entity a species under the ESA and if so (2) is the “species” in danger of extinction or likely to become an endangered species in the foreseeable future throughout all or a significant portion of its range? Green sturgeon genetic analyses showed strong differentiation between northern and southern populations, and therefore, the species was divided into Northern and Southern Distinct Population Segments (DPSs). The Northern DPS includes populations in the Rogue, Klamath-Trinity, and Eel rivers, while the Southern DPS only includes a single population in the Sacramento River. The principal risk factors for green sturgeon include loss of spawning habitat, harvest, and entrainment. The Northern DPS is not considered to be in danger of extinction or likely to become an endangered species in the foreseeable future. The loss of spawning habitat is not large enough to threaten this DPS, although the Eel River has been severely impacted by sedimentation due to poor land use practices and floods. The two main spawning populations in the Rogue and Klamath-Trinity rivers occupy separate basins reducing the potential for loss of the DPS through catastrophic events. Harvest has been substantially reduced and green sturgeon in this DPS do not face substantial entrainment loss. However there are significant concerns due to lack of information, flow and temperature issues, and habitat degradation. The Southern DPS is considered likely to become an endangered species in the foreseeable future. Green sturgeon in this DPS are concentrated into one spawning area outside of their natural habitat in the Sacramento River, making them vulnerable to catastrophic extinction. Green sturgeon spawning areas have been lost from the area above Shasta Dam on the Sacramento River and Oroville Dam on the Feather River. Entrainment of individuals into water diversion projects is an additional source of risk, and the large decline in numbers of green sturgeon entrained since 1986 causes additional concern.     

Changes in Resistance to Salinity and Temperature in Some Species of Polychaetes from the White Sea in Early Ontogenesis

We studied the effects of different salinities on plankton larvae of some polychaetes in the White Sea. It has been found that the salinity resistance of Alitta virens (Nereidae) increases during ontogenesis. Successful fertilization and further larval development in this species occur at the salinity of 22 to 34; embryos taken into the experiment at the stage of 32 blastomeres, trochophores, and early nektochaetes could survive and normally develop at the salinity of 16–32, 14–45, and 12–45 respectively. The rate of settling and metamorphosis in late nektochaetes of A. virens at normal or lowered (down to 14) salinity is dependent on temperature in the range of 5 to 23°C. It is found that the larvae of Harmothoe imbricata (Polynoidae) show the greatest salinity resistance at the stage of nektochaeta, whose lower limit of salinity is 14. Later larval stages of these species can survive in a wide range of salinity due to the development of a provisory nephridial system. The eurybionty of larvae of Spirorbis spirorbis ready for metamorphosis was higher than that in the larvae of Circeus spirillum (Spirorbidae). Under salinity reduced down to 10 the larvae of S. spirorbis die in 8–14 days, whereas more stenohaline larvae of C. spirillum die by the 3-rd day of the experiment. At water temperatures under 5°C the survival of S. spirorbis was the highest at three examined values of salinity, whereas C. spirillum showed the highest survival only under normal salinity.     

Changes in Free Amino Acids in White and Green Tissues of Variegated Tobacco Leaves during Water Stress

Variegated tobacco leaves, white on one side of the midrib andgreen on the other, were detached from the stem and incubatedunder water stress or turgid conditions for 4 days to determineany changes in the levels of free amino acids. Drastic changes in the free amino acid composition occurredin the green tissue during the water stress period, but onlyvery small changes in the white tissue. During that time, themost striking difference between the two tissues was the largeamount of proline accumulated in the green tissue, but not inthe white. An exogenous supply of sucrose increased the prolinecontent in both tissues during water stress. An exogenous supplyof glutamic acid increased the proline and asparagine contentsin the green tissue, but it increased only the asparagine contentin the white tissue during water stress. (Received May 4, 1982; Accepted August 12, 1982)     

Mitochondrial DNA Length Variation and Heteroplasmy in Populations of White Sturgeon (Acipenser Transmontanus)

Southern blot analysis was used to quantify the extent of mtDNA D-loop length variation in two populations of white sturgeon, Acipenser transmontanus. Over 42% of individuals were heteroplasmic for up to six different mtDNA length variants attributable to varying copy numbers of an 82-bp repeat sequence. Chi-square analyses revealed that the frequencies of length genotypes and the incidence of heteroplasmy were significantly different between Fraser and Columbia River sturgeon populations but not between restriction site haplotypes. Heteroplasmic fish have, on average, higher copy number than homoplasmic fish. Forty-five of 101 homoplasmic individuals carry only a single copy of the repeat, while none of the 73 heteroplasmic fish has the single repeat as the predominant variant. On the basis of differences in frequency distributions of copy number within and between fish, we suggest that (1) heteroplasmy is maintained by high recurrent mutation of multiple copy genomes, favoring increased copy number and (2) the mutation pressure toward higher copy number heteroplasmy is partially offset by selection to reduced genome size and segregation to the homoplasmic condition.     

North American Green and European Atlantic Sturgeon: Comparisons of Life Histories and Human Impacts

Green and European Atlantic sturgeon are listed as a vulnerable and a critically endangered species, respectively. These anadromous species inhabit different continents but have many similar life history traits and demographic characteristics, including wide geographic ranges, similar migratory and foraging behavior, age and size structures of reproductive stocks and, historically, diverse population structures. The differences are limited to tetraploid genome and much larger egg size and lower fecundity in green sturgeon, reflecting the adaptations to different geomorphology and biota of the Pacific region. Both species have been affected by over-harvest and habitat losses but the severity of these impacts have been greater and lasted longer for the European Atlantic sturgeon, resulting in loss of diversity and extirpation of all but one stock. From the comparison of human impact on two species we conclude that preventive actions should be taken at the early warning signs of changes in population and recruitment. These should mitigate multiple factors of human activity affecting sturgeon stocks and their habitats.     

Acute Toxicity of Arsenic under Different Temperatures and Salinity Conditions on the White Shrimp Litopenaeus vannamei

The aim of this study was to determine acute toxicity in the post larvae of the white shrimp Litopenaeus vannamei after 96 h of exposure to dissolved arsenic under three different temperatures and salinity conditions. Recent reports have shown an increase in the presence of this metalloid in coastal waters, estuaries, and lagoons along the Mexican coast. The white shrimp stands out for its adaptability to temperature and salinity changes and for being the main product for many commercial fisheries; it has the highest volume of oceanic capture and production in Mexican shrimp farms. Lethal concentrations (LC₅₀–96 h) were obtained at nine different combinations (3?×?3 combinations in total) of temperature (20, 25, and 30 °C) and salinity (17, 25, and 33) showing mean LC₅₀–96 h values (±standard error) of 9.13?±?0.76, 9.17?±?0.56, and 6.23?±?0.57 mgAs?L^?1(at 20 °C and 17, 25, and 33 salinity); 12.29?±?2.09, 8.70?±?0.82, and 8.03?±?0.59 mgAs?L^?1 (at 25 °C and 17, 25, and 33 salinity); and 7.84?±?1.30, 8.49?±?1.40, and 7.54?±?0.51 mgAs?L^?1 (at 30 °C and 17, 25, and 33 salinity), respectively. No significant differences were observed for the optimal temperature and isosmotic point of maintenance (25 °C–S 25) for the species, with respect to the other experimental conditions tested, except for at 20 °C–S 33, which was the most toxic. Toxicity under 20 °C–S 33 conditions was also higher than 25 °C–S 17 and 20 °C (S 17 or 25). The least toxic condition was 25 °C–S 17. All this suggests that the toxic effect of arsenic is not affected by temperature changes; it depends on the osmoregulatory pattern developed by the shrimp, either hyperosmotic at low salinity or hiposmotic at high salinity, as observed at least on the extreme salinity conditions here tested (17 and 33). However, further studies testing salinities near the isosmotic point (between 20 and 30 salinities) are needed to clarify these mechanisms.     

The Impact of Nutrition on Cognition in the Elderly

The possibility that nutritional manipulation may protect against cognitive decline and dementia is an inviting prospect. However data supporting a beneficial effect of a particular dietary pattern is limited. Although studies have demonstrated a health benefit to dietary plans that are high in fiber, whole grains, natural sugar and fish while maintaining lower intake in meat dairy and poultry, the ability to identify the most salient factors of these diets have been unsuccessful. Several aspects of diet have been studied in detail and provided support for potential mechanisms for improving cognition. Clinical trials have explored these mechanisms through supplementation studies with minimal benefits being observed. Continuing work to hone the mechanisms and refine our knowledge of dietary benefits is described. Special issue dedicated to John P. Blass.     

Green Sturgeon Distribution in the Pacific Ocean Estimated from Modeled Oceanographic Features and Migration Behavior

The green sturgeon (Acipenser medirostris), which is found in the eastern Pacific Ocean from Baja California to the Bering Sea, tends to be highly migratory, moving long distances among estuaries, spawning rivers, and distant coastal regions. Factors that determine the oceanic distribution of green sturgeon are unclear, but broad-scale physical conditions interacting with migration behavior may play an important role. We estimated the distribution of green sturgeon by modeling species-environment relationships using oceanographic and migration behavior covariates with maximum entropy modeling (MaxEnt) of species geographic distributions. The primary concentration of green sturgeon was estimated from approximately 41–51.5° N latitude in the coastal waters of Washington, Oregon, and Vancouver Island and in the vicinity of San Francisco and Monterey Bays from 36–37° N latitude. Unsuitably cold water temperatures in the far north and energetic efficiencies associated with prevailing water currents may provide the best explanation for the range-wide marine distribution of green sturgeon. Independent trawl records, fisheries observer records, and tagging studies corroborated our findings. However, our model also delineated patchily distributed habitat south of Monterey Bay, though there are few records of green sturgeon from this region. Green sturgeon are likely influenced by countervailing pressures governing their dispersal. They are behaviorally directed to revisit natal freshwater spawning rivers and persistent overwintering grounds in coastal marine habitats, yet they are likely physiologically bounded by abiotic and biotic environmental features. Impacts of human activities on green sturgeon or their habitat in coastal waters, such as bottom-disturbing trawl fisheries, may be minimized through marine spatial planning that makes use of high-quality species distribution information.     

The Interaction Effect to Fertilization on the Mineral Nutrition of Canola Under Different Salinity Levels

Journal of Plant Growth Regulation - The objective of this work was to study the effect of increasing rates of salinity with and without fertilizer on the mineral nutrition of canola. It is about...     

Intercellular Compartmentation of Ions in Barley Leaves in Relation to Potassium Nutrition and Salinity

X-ray microanalysis was used to determine the distributionsof several nutrient elements between vacuoles of epidermal andmesophyll cells in barley leaves and these distributions wererelated to shoot nutrient concentrations. Under the growth conditionsused, P was found only in mesophyll vacuoles, never in the epidermis.In contrast, Cl and Ca were located almost exclusively in theepidermis while K and Na were more evenly distributed betweenthe two cell types. The compartmentation of Ca and Cl in theepidermis was maintained over a wide range of tissue concentrationsof these ions. In particular, Cl was excluded from the mesophyllof salt-grown barley until the tissue concentration reachedabout 170 mol m^–3 and then it appeared in the vacuolesof these cells, but only at low concentrations. In contrast,Na was not excluded from the mesophyll of salt-grown or K-deficientbarley and there was evidence that this ion was preferentiallyaccumulated in the mesophyll. Nutrients were evenly distributedbetween the adaxial and abaxial epidermal layers, except K.which was at slightly higher concentrations in the adaxial epidermis.There was considerable variation in the concentrations of ionsin adjacent epidermal cells. The results indicate that intercellularcompartmentation of nutrients occurs in barley leaves and therole of this phenomenon in responses to nutrient deficienciesand salinity is discussed Key words: Compartmentation, barley, salinity, ions, potassium nutrition     

The Effect of Temperature Stress on Development and Heat-shock Protein Expression in Larval Green Sturgeon (Acipenser mirostris)

Water temperature is an important environmental variable influencing the distribution and health of coldwater fishes such as the green sturgeon, Acipenser medirostris. In this study, we investigated if larval sturgeon were able to tolerate or recover from acute, non-lethal temperature stress that commonly causes deformed notochords, and sought to identify the role of heat-shock proteins (hsp) in stress tolerance. The hsp response is one of the most important cellular mechanisms to prevent the damaging effects of thermal cellular stress, and differences in the ability to over-express hsps during stressful conditions may be associated with an organism’s vulnerability and the extent of thermal injury. In this study, newly hatched larvae were maintained at 17°C (control), or exposed to (a) 26°C for 3 d then maintained at 17°C until yolk-sac absorption or (b) 26°C until yolk-sac absorption. Individuals with deformed notochords were counted, and hsp60, 72, 78 and 89 were analyzed in both normal and deformed larvae by western blotting. Approximately 33% of fish developed curved notochords within the first 3 d of exposure to 26°C. After transfer to cool water 16.5% showed deformities at stage 45, suggesting a significant number of larvae had recovered. Hsp levels remained elevated for at least 9 days after termination of heat-exposure. Overall, percentage of deformed larvae, and hsp72/hsp78 levels were highest in fish continuously exposed to 26°C until yolk-sac absorption. Deformed individuals had significantly higher expression levels of hsp72 and hsp78, and lower hsp60 levels than normal larvae. We conclude that expression of hsp72 and hsp78 and potentially hsp60 are linked to phenotypic variation in the response and vulnerability of green sturgeon larvae to thermal stress.     

The Comparative Boron Nutrition of Several Green and Blue-Green Algae

The boron requirements of filamentous and non-filamentous species of green and blue-green algae have been investigated. A primary feature of this study was the quantitative analysis of the cells for boron. This permitted expression of the degree of purification of the environment and the boron requirements of the organisms in terms of cell content. Three species of green algae were shown neither to require boron nor to absorb it in appreciable amounts. In contrast, three species of blue-green algae readily absorbed boron and nitrogen fixing species showed a marked growth response to boron when nitrate was omitted from the culture medium. The response to boron was less with nitrate in the medium, probably due to increased contamination from the nitrate salt rather than an involvement of boron in the fixation process. The boron content of the deficient blue-green algae was 1–2 μg/g, suggesting a requirement below dicot angiosperms and comparable to monocots. In agreement with other reports, the fungus Penicillium chrysogenum neither required nor absorbed boron.     

Fine Structure of the Envelope and Micropyles in the Eggs of the White Sturgeon, Acipenser transmontanus Richardson

The structure of the egg envelope and micropyles of the white sturgeon was examined with light and electron microscopy. The mature ovum is 3.5–4.0 mm in diameter and is covered by a thick envelope (50 μm) that consists of four distinct layers. The outermost layer, L4, is electron dense and amorphous. Interior to this is layer three (L3), containing numerous pores, or ductules. Layer two (L2) contains screwlike projections that anchor L3 and L4 to the egg. The innermost layer, L1, is closely apposed to the oolemma. Numerous micropyles (average 7) are restricted to a 100–200 μm region at the animal pole and penetrate the egg envelope. The outer opening of these rnicropyles measures 15 μm in diameter. The micropylar canal tapers twice, eventually terminating at the oolemma with an inner opening diameter of 1.2 μm. The micropyles of the white sturgeon egg appear more complex than micropyles in other fish eggs.     

Impact of Supplementary Feeding on Reproductive Success of White Storks

European white stork (Ciconia ciconia) populations have been object to several conservation measures such as reintroduction programs, habitat improvement or supplementary feeding in the last decades. Although recent white stork censuses revealed an upward trend of most of the western populations, evaluations of the relative importance of certain conservation measures are still scarce or even lacking. In our study we analyzed the effect of supplementary feeding on the reproductive success of white storks in conjunction with other factors such as weather or nest site characteristics. We present data of 569 breeding events at 80 different nest sites located in variable distances to an artificial feeding site at Affenberg Salem (south-western Germany) collected from 1990–2012. A multilevel Poisson regression revealed that in our study population (1) reproductive success was negatively affected by monthly precipitation in April, May and June, (2) pairs breeding on power poles had a lower reproductive success than pairs breeding on platforms or trees and (3) reproductive success was significantly higher in pairs breeding in close distance to the feeding site. The number of fledglings per nest decreased by 8% per kilometer distance to the feeding site. Our data suggest that supplementary feeding increases fledgling populations which may be a tool to attenuate population losses caused by factors such as habitat deterioration or unfavorable conditions in wintering habitats.     

Impact of Soil Salinity on Barley Allelopathic Potential and Main Secondary Metabolites Gramine and Hordenine

Journal of Plant Growth Regulation - Crop allelopathy is a useful tool in integrated weed suppression. Although the abiotic stresses affect the produced secondary metabolites, the impact of soil...