The environment of bivalve Sanguinolaria rostrata growth and reproduction is affected by temperature, salinity and algal concentration.The growth and fattening of the bivalves is closely associated with filter-feeding. Hence, the present work was to investigate the effect of temperature, salinity and algal concentration on the filter-feeding of the bivalves. The salinity ranging from 5 to 30 at the interval of 5 psu, four temperatures at 20¢X, 25¢X, 27¢X and 30¢J, and three algal concentrations of each Isochrysis galbana and each Chaetoceros gracilis, 104 , 105 and 106 cells/ml, were used. Algal concentration was measured each hour and each test run last for 6 hours. A peak appeared at the salinity of 20 psu in each clearance rate vs salinity curve and clearance rate decreased with increasing algal concentration; a peak also appeared at the salinity of either 15¡ã20 psu in the ingestion rate vs salinity curve; and ingestion rate and the amount of pseudofaeces increased with increasing algal concentration. Under the conditions of algal concentration 104 cells/ml and temperature range 20¢X~30¢J, a peak appeared at 25¢J in each clearance rate and each ingestion rate vs temperature curves, and the greatest peak of clearance rate was 1.13 l/h; and the amount of pseudofaeces was the greatest at 25¢J and 20 psu. The bivalves fed with Isochrysis galbana have greater clearance and ingestion rates but less amount of pseudofaeces, compared to those fed with Chaetoceros gracilis.

There is considerable need for higher-tier aquatic risk assessment and information on toxicant-induced molecular alterations in lower aquatic invertebrates. Thus the current study&rsquo / s priorities were two-fold: a novel approach utilizing higher-tier ecotoxicity bioassay-guided ATR-FTIR (Attenuated Total Reflectance Fourier Transform Infrared) spectroscopy to better understand the impact of the presence of fish predation pressure &ndash / mimicked by predator-exuded info-chemicals &ndash / on cypermethrin or salinity toxicity to Daphnia pulex &ndash / key-stone species in lake ecosystems &ndash / and ultimately better assess toxicant-induced alterations at both organismal and molecular levels. This approach indicates that even low concentrations of cypermethrin/salinity had significant molecular and organismal effects on daphnids. Fish kairomone acted as a major factor affecting toxicant severity, interacting antagonistically below a threshold and synergistically above. Moreover, molecular ATR-FTIR spectroscopic results, clearly consistent with organismal responses, showed that both cypermethrin and salinity lead to decreased contributions of lipid and proteins to the investigated daphnid systems. It is further suggested that the action mechanism of the fish-exuded kairomone occurs via the lipid metabolism of Daphnia. Hence, infrared spectroscopic results enabled detection of early molecular alterations, whose effects might not always be observable at the organismal level. The results of this study clearly indicate that the simplistic nature of standard ecotoxicology tests hinders a precise judgment of threats imposed by chemicals of interest. Furthermore, it has been shown that ATR-FTIR spectroscopy has considerable potential for studies on daphnid responses to varying environmental conditions. Thus, this study presents a starting point for increasing the environmental realism of aquatic risk assessment.

Saltcedar is an invasive shrub that has moved into western United States riparian areas and is continuing to spread. Saltcedar is a phreatophyte that can utilize a saturated water table for moisture once established and is also highly tolerant of saline soil and water conditions. Literature has indicated that depth to the water table and salinity have a significant effect on growth and water use by saltcedar. Several studies were initiated to help develop a simulation model of saltcedar growth and water use based on the EPIC9200 simulation model. A study was initiated at the USDA-ARS Blackland Research Center Temple, Texas in the summer of 2002 to better understand the effects of water table depth and salinity on (1) saltcedar above and below ground biomass, root distribution, leaf area and (2) water use. Five different salinity levels (ranging from 0 ppm to 7500 ppm) and three different water table depths (0.5m, 1.0m, and 1.75m) were studied. Results indicated that increasing depth to the water table decreased saltcedar water use and growth. For the 0.5m water table depth, saltcedar water use during the 2002 growing season averaged 92.7 ml d-1 while the 1.75m depth averaged 56.6 ml d-1. Both root and shoot growth were depressed by increasing water table depth. Salinity had no effect on saltcedar growth or water use except at the 1250 ppm level, which used 110 ml of H2O d-1. This salinity had the highest water use indicating that this may be near the ecological optimum level of salinity for saltcedar. A predictive equation was developed for saltcedar water use using climatic data for that day, the previous day's climatic data, water table depth and salinity that included: previous day total amount of solar radiation, water table depth, previous day average wind speed, salinity, previous day total precipitation, previous day average vapor pressure, minimum relative humidity, previous day average wind direction, and maximum air temperature. Data from the field study and a potential growth study were integrated into the model. The model was parameterized for the Pecos River near Mentone, Texas. Predicted saltcedar water use was slightly lower than results reported by White et al. 2003.

Pre-mature hatching of fertilized eggs of cuttlefishes and squids, which are Taiwan¡¦s major fishing species, exists in the late embryonic development before yolk sacs are fully absorbed. It is so far unknown whether there is any difference in survival rate between pre-maturely developed juveniles and the fully developed ones. Hence, by laboratory incubation, this study aimed to discuss the relationship between the yolk size in the embryonic development process and embryo, as well as the difference in survival rate of juveniles developed at different developmental stages. The impact of the incubation time on the survival rate is explored in case of changing physical and chemical environmental factors (temperature, salinity, ammonia concentration, vibration etc.) The embryonic development of Sepia pharaonis can be divided into 40 stages according to the external shape and quality of the embryo. The embryo mantle length and the yolk diameter vary by time, while the increasing rate of the mantle length does not(F = 1.88, p = 0.06), increasing or decreasing in a linear relationship respectively. However, under the same environmental conditions, the consumption rate and the mantle size may vary in different batches(yolk diameter: F = 8.77, p < 0.01. mantle length: F = 92.14, p < 0.01). There is no difference in the surviving time of juveniles artificially and naturally incubated at the same developmental stage, and the surviving time will be longer if the artificially incubated juveniles are at later embryonic developmental stages(F = 34.66¡Ap < 0.01). With regard to the feeding ratio of juveniles pre-maturely hatched at different stages, the feeding ratio of the juveniles incubated after the 36th stage will increase with the developmental stages(F = 93.10¡Ap < 0.01). In this study, the temperature limit of the embryonic development of Sepia pharaonis should never be lower than 10¢J or higher than 35¢J, and the most suitable temperate range is between 17-28¢J. In case of sudden change in temperature, temperature increase can more effectively affect the pre-mature hatching than temperature decrease. In case of either the 36th or 39th stage embryos, if the temperature rises or drops by more than 10 degrees, pre-mature hatching can exist in some of the embryos. Some embryos may die if salinity is lowered suddenly below 20 psu. Meanwhile, pre-mature hatching may occur within one hour if it is suddenly lowered below 10 psu, and the unhatched embryos may die. When increasing the ammonia concentration suddenly to 1 and 5 ppm, the embryo incubation time may be lengthened compared with the group without the addition: some embryos may die if it is increased to 5 ppm. Meanwhile, most embryos are hatched pre-maturely within 17 minutes when it is increased to 1000 ppm, while those unhatched ones may die. In case of various environmental stimuli of the experiments, a higher percentage of embryos at the 39th stage got away from the hostile environment by pre-mature hatching, while a higher percentage of embryos at 36th stage continued the development until natural incubation or died. The vibration experiment is to produce vibration by a vertical vibration instrument. In case of 30-minute vibration at frequency of 350 times/minute and maximum amplitude at 2 cm, there is no effect on incubation time and mode of embryos at both stages. This factor is still open and subject to further discussion.

The development of environmental continuous monitoring of physicochemical parameters via portable small and inexpensive instrumentation is an active field of research as it presents distinct challenges. The development of a PCB MEMS-based inexpensive CTD system intended for the measurement of environmental parameters in natural waters, is presented in this work. Novel PCB MEMS fabrication techniques have also been developed to construct the conductivity and temperature transducers. The design and fabrication processes are based on PCB MEMS technology that combines Cu-clad liquid crystal polymer (LCP) thin-film material with a direct write photolithography tool, chemical etching and metallization of layers of electroless nickel, gold, and platinum. The basic principles of a planar four-electrode conductivity cell and the resistive temperature device are described here as well as the integration and the packaging of the microfabricated sensors for the underwater environment. Measurement results and successful field evaluation data show that the performance of the LCP thin-film microsensors can compete with that of conventional in-situ instruments.

In the subtropical oligotrophic ocean, nitrogen fixation is an important source of new nitrogen (N) for supporting biological production. Previous studies have found that nitrogen-fixing Diatom-Diazotroph Associations (DDAs) are in high abundance in the intermediate salinity zone of large river plumes such as the Amazon and Mekong rivers, while Trichodesmium spp. becomes more abundant at higher salinities. This recurring pattern in the Amazon River plume suggests that strong salinity and nutrient gradients within the river plumes may lead to a cascade in diazotroph communities. I hypothesized that the Mississippi River, a major source of freshwater, nutrients and sediments to the northern Gulf of Mexico, creates a similar distribution of diazotroph communities. The relationship between large diazotrophs and salinity was examined in samples collected in July 2011 during a flood outflow from the Mississippi River. The dominant DDA, Hemiaulus spp. – Richelia spp., was at greatest abundance (≈31,000 cells L-1) west of the birdfoot delta on the periphery of the plume (≈29 salinity) where bottom water hypoxia was also observed. Trichodesmium spp., a cyanobacterium genus that occurs in both colonial and free trichome morphologies, was abundant at both high (≈35) salinities east of the delta reaching 20+ colonies L-1, as well as in the fresher (≈28) waters of the plume where it reached 3,500 trichomes L-1. Diazotroph distributions were separated east and west of the Mississippi River outflow, with DDAs being most abundant over bottom water hypoxic regions to the west and Trichodesmium spp. in high abundance to the east. The diazotroph – salinity gradient relationships present within the Amazon River plume were not present within the Gulf of Mexico. This study suggests that environmental factors other than salinity, such as nutrients or hypoxia, are influencing the distribution of diazotrophs around the Mississippi River plume. The seasonal hypoxia seen in the Gulf of Mexico with the co-occurring DDA increase could appear in other river systems. / text

There is limited information currently available regarding the underlying physiological responses and molecular mechanisms of osmoregulation, acetate metabolism [in relation to the synthesis of glycerolipids, polyunsaturated fatty acids (PUFA), and ichthyotoxins], and transport in Prymnesium parvum N. Carter, a microalga that causes devastating harmful algal blooms (HAB) worldwide. This dissertation examines gene expression under environmental conditions that are associated with HAB formation, including phosphate limitation and low salinity, using microarrays and RNA sequencing (RNA-Seq). A comparative fatty acid methyl ester (FAME) analysis at 30 vs. 5 practical salinity units (psu) was performed to gain additional insight into acetate metabolism. The RNA-Seq analysis included a de novo assembly of the P. parvum transcriptome, generating 47,289 transcripts, of which 35.4% were identifiable. This permitted the evaluation of the expression of many more genes compared with the microarray analysis, which examined ~3,500 genes. Relevant candidate genes identified included those whose products are involved in osmolyte production, salinity stress, and ion transport. With respect to the putative synthesis of polyketide ichthyotoxins, 32 different polyketide synthase (PKS) transcripts were identified in the transcriptome assembly, none of which were differentially expressed. Hemolysin and monogalactosyldiacylglycerol synthase were downregulated at 30 vs. 5 psu, suggesting the increased presence of additional ichthyotoxins at the lower salinity. Evidence for several PUFA synthesis pathways was also revealed. Fatty acid compositions were largely similar at the two salinities, containing relatively prominent quantities of the PUFA stearidonic acid, but compositions varied among strains. The transcription of genes whose products are associated with vesicular transport was elevated, and higher levels of extracellular prymnesins were observed in HAB-forming conditions. Thus, with regard to acetate metabolism, I have revealed evidence for the post-transcriptional regulation of the production of prymnesins and the contributory effects of hemolysin, monogalactosyldiacylglycerol, and PUFA towards ichthyotoxicity. Further, I propose that toxin transport is triggered in HAB-forming conditions, in which the toxins are actively being excreted. Collectively, these data shed light on the transcriptional responses that occur following alterations in phosphate availability and salinity, including those associated with the synthesis and delivery of a number of potential ichthyotoxins from P. parvum. / text

Hypoxia is frequently detected during summer in Corpus Christi Bay, Texas, and causes significant harm to benthic organism population and diversity. Hypoxia is associated with the density stratification in the Bay but the cause of stratification is uncertain. To support the study of hypoxia and stratification, a cyberinfrastructure based on the CUAHSI (Consortium of Universities for the Advancement of Hydrologic Science, Inc) Hydrologic Information System (HIS) is implemented. HIS unites the sensor networks in the Bay by providing a standard data language and protocol for transferring data. Thus hypoxia-related data from multiple sources can be compiled into a structured database. In Corpus Christi Bay, salinity data collected from many locations and times are synthesized into a three-dimensional space-time continuum using geostatistical methods. The three dimensions are the depth, the distance along a transect line, and time. The kriged salinity concentration in space and time illuminates the pattern of movement of a saline gravity current along the bottom of the Bay. The travel time of a gravity current in the Bay is estimated to be on the order of one week and the speed is on the order of 1 km per day. Statistical study of high-resolution wind data shows that the stratification pattern in the Bay is related to the occurrence of strong, southeasterly winds in the 5 days prior to the observation. This relationship supports the hypothesis that stratification is caused by the wind initiating hypersaline gravity currents which flow from Laguna Madre into Corpus Christi Bay. An empirical physical hypoxia model is created that tracks the fate and transport of the gravity currents. The model uses wind and water quality data from real-time sensors published by HIS to predict the extent and duration of hypoxic regions in the Bay. Comparison of model results with historical data from 2005 to 2008 shows that wind-driven gravity currents can explain the spatially heterogeneous patterns of hypoxic zones in Corpus Christi Bay. / text

Viruses have an estimated global population size of 10 to the 31st, with a significant proportion found in the marine environment. Viral lysis of bacteria affects the flow of carbon in the marine microbial food web, but the effects of lysogeny on marine microbial ecology are largely unknown. In this thesis, factors that influence the control of lysogeny were studied in both the phiHSIC/Listonella pelagia phage-host system and in bacterioplankton populations in the Gulf of Mexico. Using macroarrays dotted with phiHSIC amplicons, viral gene expression over the course of a synchronous infection experiment was measured. Early, middle, late, and continually expressed genes were identified, and included open reading frames 45, 28, 18 and 17, respectively. Viral gene expression in cultures of the HSIC-1a pseudolysogen grown in low and normal salinity media was also analyzed. Overall, levels of viral gene expression were higher in the 39 ppt treatment as compared to the 11 ppt tre atment for most ORFs. In the 11 ppt treatment, free phage concentrations were one to two orders of magnitude lower than the 39 ppt treatment while intracellular phage concentrations were one-fold lower. Therefore, at low salinities, expression of phiHSIC genes is repressed resulting in a lysogenic-like state, while at 39 ppt, lytic interactions dominated. Few viral genes were highly expressed at low salinity, suggesting that repression of viral genes was controlled by host genes. Samples from the eutrophic Mississippi River Plume and the oligotrophic Gulf of Mexico were analyzed for lytic phage production and occurrence of lysogeny. Significant lytic viral production was only observed three stations, none of which were located within the MRP. This signifies that system productivity is not an accurate predictor of viral productivity. The lysogenic fraction was also inversely correlated to bacterial activity, which decreased with depth. These findings support the hypothesis that lysogeny is a survival mechanism for phages when host cell density is low or when conditions do not favor growth. A unifying theme from these experiments was that lytic processes dominated when bacterial growth conditions were optimal, while lysogeny was observed at unfavorable growth conditions or environmental stress (low salinity).

A monthly resolved coral δ18O record from Sabine Bank, Vanuatu (SBV; 166.04° E, 15.94°S), extending from 2006 to 1929 CE, is used to assess the influence of sea surface salinity (SSS) on the oxygen isotopic composition of coral aragonite at this location. Monthly SSS anomalies at SBV between 2006 and 1970 are strongly correlated with monthly anomalies in sea surface temperature (SST) variations in the central Pacific cold tongue, as recorded by SST anomalies in the Niño 3.4 grid box (i.e., canonical record of ENSO variability, r = 0.68, p < 0.01; lag of 6 months). This relationship demonstrates that SSS in the waters offshore of Vanuatu respond to ENSO-driven changes in the coupled ocean-atmosphere system in the tropical Pacific. SBV coral δ18O is also strongly correlated with monthly instrumental SSS anomalies at Vanuatu (r = 0.71, p < 0.01), therefore SBV coral δ18O variations are driven by the ENSO-related changes in surface ocean conditions. A calibration-verification exercise using SBV coral δ18O values and instrumental SSS was performed over the period 2006-1970 CE. A statistically robust transfer function was determined and used to predict SSS at SBV back to 1929 CE. The coral δ18O and SSS relationship at Vanuatu is further evaluated via comparison with a coral δ18O record from Malo Channel, Vanuatu, a site that is 130 km to the east of SBV. The strong correlation between the two coral δ18O records (r = 0.70; p < 0.01) suggests that ENSO drives regional changes in SSS in this region and that such changes can be reconstructed using variations in skeletal δ18O of corals. / text