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Your search keyword '"Physicochemical conditions"' showing total 5 results
Start Over Descriptor "Physicochemical conditions" Topic salinity
5 results on '"Physicochemical conditions"'

1. Biological and chemical responses in a temporarily open/closed estuary to variable freshwater inputs.

Author

Collins, Darcie and Melack, John

Subjects
*ESTUARIES, *LAGOON ecology, *BIOLOGICAL research, *WATER chemistry, *EFFECT of salt on fishes, *FRESHWATER biology
Abstract

In coastal lagoons with occasional connection to oceans, variations in physicochemical conditions and biological responses can be pronounced. To examine the influence of variable rainfall and tidal flushing, we measured, over a 4-year period, salinity, temperature and dissolved oxygen, and fish abundances, in Devereux Slough, a coastal lagoon occasionally connected to the Pacific Ocean along the California coast. We test the hypotheses that salinity is the primary influence on fish composition, and that fish density is affected by freshwater discharge and by berm breaches. During our sampled years, annual rainfall varied from 188 to 971 mm, and the sand berm separating the Slough from the ocean breached in each year except 2007, a drought period. Average yearly salinity ranged from 7.7 to 37.1 ppt. Hypoxic conditions in the near-bottom water were common each year. The best predictor of the fish composition was salinity, and an indirect correlation with fresh water discharge was responsible for much of the temporal variation in the fish assemblage. The interaction between salinity, state of the estuary mouth (open vs. closed), and precipitation significantly predicted densities of Fundulus parvipinnis (Girard 1984). [ABSTRACT FROM AUTHOR]

Published
2014
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2. The physicochemical conditions of hydrothermal ore-forming systems of “black smokers” associated with mantle ultrabasites in the Central Atlantic region.

Author

Bortnikov, N.S., Simonov, V.A., Amplieva, E.E., Stavrova, O.O., and Fouquet, Y.

Subjects
FLUID inclusions, HYDROTHERMAL deposits, HYDROTHERMAL vents, MANTLE plumes, LOW temperatures, SALINITY, BASALT
Abstract

Abstract: Study of fluid inclusions in minerals from sulfide ores sampled in the Ashadze and Logatchev hydrothermal fields during the Serpentine cruise of the R/V Pourquoi Pas? in 2007 gave an insight into the physicochemical conditions of ore-forming systems of “black smokers” associated with mantle ultrabasites in the Central Atlantic region. It was established that the studied hydrothermal systems differ in mineral formation temperatures, fluid salinity, and hydrothermal processes running within basaltic complexes in both low-spreading (Mid-Atlantic Ridge) and high-spreading (East Pacific Rise) mid-ocean ridges. It was shown for the Ashadze and Logatchev hydrothermal fields that the temperatures and salinity of inclusion solutions in the minerals vary over a wider range of values than those of fluids flowing out from the ridge vents onto the ocean floor. Study of fluid inclusions showed that the Ashadze and Logatchev sulfide structures resulted from the action of both high-temperature (up to 355 °C) and low-temperature (no lower than 170 °C) solutions. The salinity of fluid in the inclusions (mainly 8 wt.%) is more than twice as high as the salinity of seawater. The data obtained substantiate the phase separation of fluid in the deepest-water submarine hydrothermal Ashadze system and give an idea of the chemical composition and temperature of fluids forming sulfide deposits in the Ashadze and Logatchev hydrothermal fields in the Central Atlantic region. [Copyright &y& Elsevier]

Published
2011
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3. CONDICIONES FISICOQUÍMICAS DEL PUERTO DE ENSENADA, BAJA CALIFORNIA, CON VISTAS A LA INSTALACIÓN DE UN SISTEMA DE BOMBEO POR ENERGÍA DEL OLEAJE (SIBEO).

Author

De Zayas, Roberto González, De La Lanza Espino, Guadalupe, and Czitrom Baus, Steven

Subjects
*HARBORS, *PUMPING machinery, *SALINITY, *CHEMICAL oxygen demand, *WATER pollution, PORT of Ensenada (Mexico City, Mexico)
Abstract

The Port of Ensenada, Baja California, is one of the most important in the Pacific coast of Mexico. It has experienced an increase of the anthropogenic activities in the last decades, which together with its limited circulation, has brought about possible changes in the physiochemical characteristics of its waters. The main objective of the present work is the spatial and seasonal characterization of the physiochemical parameters of the waters of the port to install a Wave Energy Pump System (SIBEO). The investigation was carried out in 18 stations, with a quarterly frequency and the parameters were: temperature, salinity, dissolved oxygen, nutrients (ammonium, nitrates + nitrites, phosphates and silicates), chlorophyll "a" and chemical oxygen demand (COD). The results indicated that the thermohaline structure of the port was similar to that of the Bay of Todos Santos and it was associated to seasonal cycles, with the highest temperatures in summer (22 °C) and lowest in autumn (16 °C). The spatial and seasonal distribution of nutrients and organic matter was due to several factors, that is: waste disposal, resuspension of sediments and existence of cyclonal turns in front of the jetties of cruises and containers. Particularly, in November, the hypoxic conditions (<3 ml/L) and the highest contents in ammonium (19.0 µM), nitrates + nitrites (3.1 µM), phosphates (2.8 µM), silicates (12 µM) and DQO (28 mgO2/L) in the northern area, reflected a bigger to smaller gradient from the northern area toward the mouth. [ABSTRACT FROM AUTHOR]

Published
2006

4. The effect of temperature, salinity, eyestalk ablation, and limb removal on growth and survival of juvenile paddle crab, Ovalipes trimaculatus (Brachyura: Portunidae)

Author

Rodrigo D Hernadez-Moresino, Pedro J. Barón, Antonela Martelli, and Lourdes Barki

Subjects
0106 biological sciences, animal structures, Eyestalk ablation, Otras Ciencias Biológicas, Temperature salinity diagrams, Captivity, Aquatic Science, Oceanography, 01 natural sciences, CULTURE CONDITIONS, Ciencias Biológicas, Animal science, Juvenile, biology, CRAB NURSERY, PHYSICOCHEMICAL CONDITIONS, 010604 marine biology & hydrobiology, Physiological condition, food and beverages, biology.organism_classification, Crustacean, EYESTALK ABLATION, Salinity, AUTOTOMY, MOLTING SUCCESS, Portunidae, CIENCIAS NATURALES Y EXACTAS
Abstract

Crustacean growth in nature is affected by hormonal processes and natural stressors. For aquaculture purposes, paddle crab, Ovalipes trimaculatus (De Haan, 1833), juveniles were subjected to experimental eyestalk ablation, limb removal, and a combination 3 × 3 temperature and salinity conditions. Relative lifetime in captivity (RLC), molting success (MS), molting interval (MI), growth in terms of size and weight after molting (SI and WI), specific growth rate in size (SGRs) and weight (SGRw), and hepatosomatic index (HS) were evaluated in eight replicate groups of crabs for each treatment (one crab per tank). RLC was significantly lower in eyestalk-ablated crabs than in those subjected to limb removal and to control conditions (no organ removal, 13 °C, salinity of 33); it was significantly higher in crabs held at a salinity of 30 vs those maintained at 33 and 27. Combinations of 16 or 19 °C and salinity of 30 provided the optimal conditions of growth in size and weight. Results suggest that control of temperature and salinity can improve growth and survival of juveniles in captivity. However, organ removal did not promote molting in captivity, likely to the detriment of survival and physiological condition. Findings from the present study highlight the importance of carefully selecting conditions to rear this valuable commercial crab to promote its aquaculture in the region. Fil: Martelli, Antonela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina Fil: Hernández Moresino, Rodrigo Daniel. Universidad Tecnológica Nacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina Fil: Barki, Lourdes. Universidad Nacional de la Patagonia "San Juan Bosco"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina Fil: Baron, Pedro Jose. Universidad Nacional de la Patagonia "San Juan Bosco"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina. Universidad Tecnológica Nacional; Argentina

Published
2019

5. Spatial and temporal variation of the nekton and hyperbenthos from a temperate European estuary with regulated freshwater inflow

Author

Ignacio Sobrino, Carlos Fernández-Delgado, D. García-González, José A. Cuesta, Antonio Rodríguez, Alberto M. Arias, Pilar Drake, Francisco Baldó, and A. Silva-García

Subjects
geography, Freshwater inflow, geography.geographical_feature_category, Macrofaunal, Ecology, Nekton, Community structure, Estuary, Hyperbenthos, Aquatic Science, Centro Oceanográfico de Cádiz, Salinity, Oceanography, Guadalquivir estuary, Physicochemical conditions, River mouth, Environmental Chemistry, Environmental science, Spatial variability, Species richness, Medio Marino, General Environmental Science, European estuaries
Abstract

18 páginas, 11 figuras, 8 tablas., The aquatic macrofauna of the Guadalquivir estuary were sampled (1 mm mesh persiana net) at 5 sampling sites located along the entire (except the tidal freshwater region) estuarine gradient of salinity (outer 50 km). A total of 134 fish and macroinvertebrate species was collected but only 62 were considered common or regularly present in the estuary. Univariate measures of the community structure showed statistically significant differences among sampling sites: species richness, abundance, and biomass decreased in the upstream direction, being positively correlated with the salinity. Temporal differences of these three variables were also statistically significant. While a clear seasonal pattern (minimum densities in winter and maximum in spring-summer) was observed for abundance and biomass, no such pattern existed for the number of species. Mysids was the most dominant group throughout the estuary (96% to 99% of abundance; 49% to 85% of biomass), although fish biomass was also important at the outer estuary (36% to 38%). Multivariate analyses indicated highly significant spatial variation in the macrofaunal communities observed along the salinity gradient. These analyses suggest that the underlying structure was a continuum with more or less overlapping distributions of the species dependent on their ability to tolerate different physicochemical conditions. There were also significant temporal (intermonthly + interannual) variation of the estuarine community; the relative multivariate dispersion indicated that monthly variation was more considerable (relative multivariate dispersion >1) at the outer part of the estuary during the wet year (last 20 km) and was higher in the inner stations during the dry year (32 to 50 km from the river mouth). Since a clear negative exponential relationship was observed between the freshwater input (from a dam located 110 km upstream) and water salinity at all sampling stations, it is concluded that the human freshwater management is probably affecting the studied estuarine communities. While the higher seasonal (long-term) stability of the salinity gradient, due to the human control of the freshwater input, may facilitate the recruitment of marine species juveniles during the meteorologically unstable early-spring, the additional (short-term) salinity fluctuations during the warm period may negatively affect species that complete their lifecycle within the estuary., This research was supported by the Junta de Andalucía within the project ‘‘Ordenación y regulación de la actividad pesquera en el estuario del Guadalquivir.’’

Published
2002

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