Small Changes In Salinity Research Articles

Trait response of three Baltic Sea spring dinoflagellates to temperature, salinity, and light gradients

Climate change is driving Baltic Sea shifts, with predictions for decrease in salinity and increase in temperature and light limitation. Understanding the responses of the spring phytoplankton community to these shifts is essential to assess potential changes in the Baltic Sea biogeochemical cycles and functioning. In this study we use a high-throughput well-plate setup to experimentally define growth and the light acquisition traits over gradients of salinity, temperature and irradiance for three dinoflagellates commonly occurring during spring in the Baltic Sea, Apocalathium malmogiense, Gymnodinium corollarium and Heterocapsa arctica subsp. frigida. By analysing the response of cell volume, growth, and light-acquisition traits to temperature and salinity gradients, we showed that each of the three dinoflagellates have their own niches and preferences and are affected differently by small changes in salinity and temperature. A. malmogiense has a more generalist strategy, its growth being less affected by temperature, salinity, and light gradients in comparison to the other tested dinoflagellates, with G. corollarium growth being more sensitive to higher light intensities. On the other hand, G. corollarium light acquisition traits seem to be less sensitive to changes in temperature and salinity than those of A. malmogiense and H. arctica subsp. frigida. We contextualized our experimental findings using data collected on ships-of-opportunity between 1993-2011 over natural temperature and salinity gradients in the Baltic Sea. The Apocalathium complex and H. arctica subsp. frigida were mostly found in temperatures<10°C and salinities 4-10 ‰, matching the temperature and salinity gradients used in our experiments. Our results illustrate that trait information can complement phytoplankton monitoring observations, providing powerful tools to answer questions related to species’ capacity to adapt and compete under a changing environment.

Salinization Increase due to Climate Change Will Have Substantial Negative Effects on Inland Waters: A Call for Multifaceted Research at the Local and Global Scale

Salinization Increase due to Climate Change Will Have Substantial Negative Effects on Inland Waters: A Call for Multifaceted Research at the Local and Global Scale

Recruitment variability in Baltic flounder (Platichthys solemdali) – effects of salinity with implications for stock development facing climate change

The brackish water Baltic Sea is strongly influenced by irregular saline water inflows. Fewer inflow events since the 1980s have resulted in a decrease in salinity, and will according to predicted climate change continue to decrease. The newly described Baltic flounder Platichthys solemdali has adapted to reproduction at low salinity conditions since it colonized the Baltic Sea 7000 years BP; in the area studied (ICES SD 3d 28.2) spawning occurs at 3–20 m depth at ca 7 psu. Here we monitored variability in year-class strength as newly settled 0-gr fish in three coastal nursery areas, and compared obtained recruitment indices with prevailing temperature and salinity conditions. 0-gr abundance indices varied considerably between years, from 1 to 90, 10–296 and 17–86 at the respective sampling site, and showed strong accordance with the age structure of the adult stock. Variability in temperature showed no effect, but stronger and weaker year-classes respectively were related to variability in salinity in the range 6.6–7.1 psu with stronger year-classes at >6.8 psu. This coincides with variability in spermatozoa motility, fertilization rates and early egg development at different salinities and suggests that the year-class strength may be set already at the egg stage. Thus, only small changes in salinity at spawning may affect reproductive success and ultimately stock development. The potential effects on stock abundance and distribution facing climate change call for changes in future fishing patterns as well as adaptations in management to prevent stock collapse.

Quantification of small-scale heterogeneity in aquatic aminopeptidase activity

Leucine aminopeptidase (LAP) is one of the enzymes involved in the hydrolysis of peptides, and is sometimes used to indicate potential nitrogen limitation in microbes. Small-scale variability has the potential to confound interpretation of underlying patterns in LAP activity in time or space. An automated flow-injection analysis instrument was used to address the small-scale variability of LAP activity within contiguous regions of the Hudson River plume (New Jersey, USA). LAP activity had a coefficient of variation (CV) of ca. 0.5 with occasional values above 1.0. The mean CVs for other biological parameters—chlorophyll fluorescence and nitrate concentration—were similar, and were much lower for salinity. LAP activity changed by an average of 35 nmol l-1 h-1 at different salinities, and variations in LAP activity were higher crossing region boundaries than within a region. Differences in LAP activity were ±100 nmol l-1 h-1 between sequential samples spaced <10 m apart. Variogram analysis indicated an inherent spatial variability of 52 nmol l-1 h-1 throughout the study area. Large changes in LAP activity were often associated with small changes in salinity and chlorophyll fluorescence, and were sensitive to the sampling frequency. This study concludes that LAP measurements in a sample could realistically be expected to range from zero to twice the average, and changes between areas or times should be at least 2-fold to have some degree of confidence that apparent patterns (or lack thereof) in activity are real.

High salinity tolerance of the Red Sea coral Fungia granulosa under desalination concentrate discharge conditions: an in situ photophysiology experiment

Seawater reverse osmosis desalination concentrate may have chronic/acute impacts on the marine ecosystems in the near-field area of the discharge. Environmental impact of the desalination plant discharge is supposedly site- and volumetric specific, and also depends on the salinity tolerance of the organisms inhabiting the water column in and around a discharge environment. Scientific studies that aim to understand possible impacts of elevated salinity levels are important to assess detrimental effects to organisms, especially for species with no mechanism of osmoregulation, e.g. presumably corals. Previous studies on corals indicate sensitivity towards hypo- and hyper-saline environments with small changes in salinity already affecting coral physiology. In order to evaluate sensitivity of Red Sea corals to increase salinity levels, we conducted a long-term (29 days) in situ salinity tolerance transect study at an offshore seawater reverse osmosis discharge on the coral Fungia granulosa. While we measured a pronounced increase in salinity and temperature at the direct outlet of the discharge structure, effects were indistinguishable from the surrounding environment at a distance of 5 m. Interestingly, corals were not affected by varying salinity levels as indicated by measurement of the photosynthetic efficiency. Similarly, cultured coral symbionts of the genus Symbiodinium displayed remarkable tolerance levels in regard to hypo- and hypersaline treatments. Our data suggest that increased salinity and temperature levels from discharge outlets wear off quickly in the surrounding environment. Furthermore, Fungia granulosa seem to tolerate levels of salinity that are distinctively higher than reported for other corals previously. It remains to be determined whether Red Sea corals in general display increased salinity tolerance, and whether this is related to prevailing levels of high(er) salinity in the Red Sea in comparison to other oceans.

Effect of EPA/DHA ratios on the growth and survival of Galaxias maculatus (Jenyns, 1842) larvae reared under different salinity regimes

Despite the importance of certain highly unsaturated fatty acids in osmotic regulation, few studies have been addressed to determine the essential fatty acid requirements for a given species cultured under different salinities. As Galaxias maculatus is a diadromic species, the present study aimed to determine the effect of salinity on the optimum dietary EPA/docosahexaenoic (DHA) ratio for survival and growth during the larval stages. Larvae were fed for 20 days with rotifers containing two different EPA/DHA ratios (low: 0.64 and high: 2.18) at three different salinities (0, 10 and 15 g L−1). The results of this study showed a marked effect of water salinity on larval dietary lipid utilization in G. maculatus larvae. These results suggested that G. maculatus larvae reared at higher salinities may have a higher dietary requirement for DHA, whereas larvae reared at 0‰ showed higher requirements for EPA. The overall results of the present study indicate that even small changes in salinity can determine the optimum dietary EPA/DHA ratio and the quantitative essential fatty requirements of fish. This may have important repercussions and affect the rearing performance of G. maculatus cultured under different salinities.

Short-term impacts of enhanced Greenland freshwater fluxes in an eddy-permitting ocean model

Abstract. In a sensitivity experiment, an eddy-permitting ocean general circulation model is forced with realistic freshwater fluxes from the Greenland Ice Sheet, averaged for the period 1991–2000. The fluxes are obtained with a mass balance model for the ice sheet, forced with the ERA-40 reanalysis dataset. The freshwater flux is distributed around Greenland as an additional term in prescribed runoff, representing seasonal melting of the ice sheet and a fixed year-round iceberg calving flux, for 8.5 model years. By adding Greenland freshwater fluxes with realistic geographical distribution and seasonality, the experiment is designed to investigate the oceanic response to a sudden and spatially/temporally uniform amplification of ice sheet melting and discharge, rather than localized or gradual changes in freshwater flux. The impacts on regional hydrography and circulation are investigated by comparing the sensitivity experiment to a control experiment, without additional fluxes. By the end of the sensitivity experiment, the majority of additional fresh water has accumulated in Baffin Bay, and only a small fraction has reached the interior of the Labrador Sea, where winter mixed layer depth is sensitive to small changes in salinity. As a consequence, the impact on large-scale circulation is very slight. An indirect impact of strong freshening off the west coast of Greenland is a small anti-cyclonic component to the circulation around Greenland, which opposes the wind-driven cyclonic circulation and reduces net southward flow through the Canadian Archipelago by ~10%. Implications for the post-2000 acceleration of Greenland mass loss are discussed.

Influence of salinity on light conditions and phytoplankton growth in a turbid river

AbstractA turbid lowland river in Australia was studied to describe factors influencing the light conditions for phytoplankton growth. Vertical attenuation coefficients correlated with nepholometric turbidity enabling estimation of euphotic depths (z eu) from long term turbidity monitoring. Light conditions were assessed from the ratio of zeu to the maximum water depth (zm). Predominantly zeu/zm ratios were below 0.2, a value indicating the minimum light conditions required to support phytoplankton growth. A transitional state with zeu/zm between 0.2 and 0.35 occurred 15% of the time, while light sufficiency occurred for 30% of the time. Peaks in eukaryotic phytoplankton biomass developed when zeu/zm was at or above transitional values. Large increases in cyanobacterial numbers (Anabaena sp.) only occurred when zeu/zm exceeded 0.35. Turbidity increased quickly with elevated flows but did not decline substantially as flows reduced and light limiting conditions extended into low flow periods otherwise conducive to phytoplankton growth. However, during extended periods of reduced flows conductivity increased causing a substantial reduction in turbidity with concomitant improvements in light penetration. A turbidity of ca. 100 NTU marked the transition to light sufficiency at the study site and occurred at a conductivity of ca. 300 µS cm−1 demonstrating that small changes in salinity can have major effects on light penetration. These results show that flow, salinity and turbidity all play a part in determining the growth conditions for phytoplankton in turbid rivers. Copyright © 2009 John Wiley & Sons, Ltd.

EMERGING ISSUES FOR THE RESTORATION OF TIDAL MARSH ECOSYSTEMS IN THE CONTEXT OF PREDICTED CLIMATE CHANGE

There is currently a large regional effort to restore tidal marsh ecosystems in the San Francisco Bay-Delta Estuary involving the commitment of hundreds of millions of dollars and broad landscape-scale habitat manipulations. Although climate change has been on the horizon for many years, recent developments suggest that it must be taken seriously as a factor to be considered in future planning for marsh restoration efforts. Tidal marshes are vulnerable to changes in salinity and inundation rates, both of which will be affected by climate change. Restoration sites may be particularly vulnerable given unpredictable sediment inputs and newly established vegetation. Predicted shifts in snowmelt and altered runoff will change estuarine salinity patterns and could have large-scale impacts on marsh dominance, especially for freshwater marshes. Even relatively small salinity changes could lead to shifts in dominant species, with freshwater marshes being replaced by brackish marshes and brackish marshes converted to salt marsh communities. This will cause a reduction in overall estuarine plant diversity and productivity, with possible reverberations for the estuarine food web. Based on monitoring data from San Francisco Bay marshes, we predict that salinity will have a more immediate impact on tidal marsh vegetation than sea-level rise. However, sea-level rise poses a potentially greater long-term threat, depending on its rate, because the effects of inundation and a more persistent salinity regime could cause widespread marsh loss. If ice sheets in Antarctica and Greenland begin melting at rapid rates, inundation impacts could be catastrophic for coastal marshes. Given the magnitude of these potential changes, we urge the restoration and conservation management community to integrate these contingencies into adaptive management process and to join with the broader community in forging more flexible governance institutions that can respond effectively to large-scale uncertainties and trajectories as they unfold.

Community structure of shoreline nekton in the estuarine portion of the Alafia River, Florida: Differences along a salinity gradient and inflow-related changes

Determination of baseline biological conditions in Florida's rivers is required prior to increased water withdrawals for the rapidly growing human population. We studied the small-bodied shoreline nekton community of the estuarine portion of the Alafia River (a tributary of Tampa Bay, SW Florida) from 1998 to 2003 using 21.3-m seines of 3.2-mm stretched mesh. Community structure along the estuarine salinity gradient changed from dominance by marine and estuarine transients from river km 0 to 9.3 to greater abundances of resident low-salinity and freshwater forms near the tidal–freshwater interface (river km 9.3–14). There was evidence that the magnitude of the freshwater inflow influenced nekton community patterns along the estuary, with the center of abundance of many species shifting in response to inflow. The community structure of the nekton of river km 0–9.3 showed regular seasonal changes that were of greater importance than was temporal correlation with abiotic variables (temperature, salinity, inflow); these changes can be explained by predictable spawning patterns of transient species. In contrast, changes in the structure of the nekton community in river km 9.3–14 were well correlated with changes in salinity and, to a lesser extent, inflow. The sensitivity of the nekton to relatively small changes in salinity near the tidal–freshwater interface is of importance given that comparatively minor changes in freshwater inflow could markedly affect salinities in this upstream region.

Osmoregulation in the Sheepshead Minnow, Cyprinodon variegatus: Influence of a Fluctuating Salinity Regime

Cyprinodon variegatus (sheepshead minnow), a common coastal resident of the western Atlantic Ocean and Gulf of Mexico, can live in ambient salinities ranging from 0‰ to greater than 140‰. Fish in this study were obtained from a Gulf of Mexico salt marsh near Cedar Key, Florida. This study examined the ability of individual C. variegatus to regulate plasma osmolality under the influence of a cycling salinity regime. Individuals of C. variegatus were exposed for 21 d to one of seven cyclical salinity regimes. Each cycle lasted for 2 d, with salinity varied between 10‰ and 30‰ each day. Plasma osmolality of fish from each group was determined on five dates during the course of the experiment. C. variegatus efficiently regulated plasma osmolality, even when fishes were exposed to large fluctuations in salinity. Fish previously exposed to large salinity fluctuations regulated plasma osmolality better than fish that previously had experienced no change or small changes in salinity. Increasing salinity had a greater impact on osmoregulation than did decreasing salinity.

Effect of small variations in salinity on the rates of photosynthesis and respiration of the zooxanthellate coral Stylophora pistillata

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 181:309-314 (1999) - doi:10.3354/meps181309 Effect of small variations in salinity on the rates of photosynthesis and respiration of the zooxanthellate coral Stylophora pistillata C. Ferrier-Pagès1,*, J.-P. Gattuso2, J. Jaubert1 1Observatoire Océanologique Européen, Centre Scientifique de Monaco, Av. Saint-Martin, MC-98000, Monaco 2Observatoire Océanologique, LOBEPM, UPRESA 7076, CNRS, BP 28, F-06234 Villefranche-sur-Mer cedex, France *E-mail: ferrier@naxos.unice.fr ABSTRACT: This paper deals with the effect of a long term (3 wk) change in salinity (increase or decrease of 2 to 4 psu) on the rates of photosynthesis and respiration of the zooxanthellate coral Stylophora pistillata. Colonies were exposed to 4 levels of salinity (34, 36, 38 and 40 psu, with 38 psu as the control salinity) and results were compared using 1-factor ANOVAs. Salinity had a significant effect on the protein concentration. It was 30% higher at 38 psu than at the other salinities. It had also a significant effect on the rates of photosynthesis, respiration and on the Pg:R ratio. Gross maximal photosynthetic rates were 50% lower at 34, 36 and 40 psu than at 38 psu. The Pg:R ratio was always higher at the control salinity. Most of the colonies maintained at 40 psu died, and this was explained by a very low Pg:R ratio (<1). S. pistillata is therefore especially sensitive to small changes in salinity and seems to acclimate more easily to hypo- rather than to hypersaline conditions. KEY WORDS: Scleractinian · Coral · Photosynthesis · Respiration · Salinity Full text in pdf format PreviousExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 181. Publication date: May 18, 1999 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1999 Inter-Research.

Early-indicator signals of groundwater contamination: the case of seawater encroachment

An early indication of groundwater contamination occurs when pollutant concentrations start to fluctuate and exceed background values of ambient fresh groundwater. An analysis of a characteristic situation of this type uses data from Israel's coastal phreatic granular aquifer. The pollutant is generally seawater, and the contamination process involves replacement of freshwater by encroaching sea- or other saltwater, a process augmented by human activity. The contamination process involves three stages: (1) groundwater composition remains relatively stable with small salinity content; (2) small salinity changes are perceptible with reversible fluctuations; and (3) salinity concentration increases at a sharply higher rate. The second stage is a useful early-indicator signal of contamination. Early-indicator signals of groundwater pollutant concentrations involve "minor" fluctuations in water chemistry at the advent of the contamination process. The intensity and magnitude of such a salinization/pollution process at any given location depends upon lithologic matrix, aquifer heterogeneity, and resultant flow domain characteristics, as well as contaminant properties. If such "signs" are detected at a sufficiently early stage, appropriate management steps may be taken to rectify further seawater and/or saltwater encroachment.

Reduced meltwater outflow from the Laurentide ice margin during the Younger Dryas

THE cause of the Younger Dryas cold event, which interrupted the last deglaciation, is still a matter of debate1. A prevalent hypothesis, proposed by Broecker et al.2 is that the abrupt climate change was driven by a decrease in the rate of North Atlantic Deep Water production, triggered by a sudden dilution of North Atlantic surface water in response to the diversion of Laurentide icesheet melt water from the Mississippi drainage system to that of the St Lawrence river. Here we investigate the feasibility of this triggering mechanism by reconstructing sea-surface temperature, salinity and sea-ice cover records for the outlet of the Gulf of St Lawrence into the North Atlantic Ocean. These reconstructions—based on dinoflagellate-cyst assemblages3,4 in sediment cores from the region—show reduced meltwater runoff, low temperatures and extensive sea-ice cover during the Younger Dryas, dated here between 10,800 and 10,300 BP. Meltwater pulses did occur before and after the Younger Dryas event: as early as 11,700 BP, during the development of the Champlain Sea in the St Lawrence Lowland, and afterwards, until ~ 10,100 BP. At the resolution of our salinity proxy (0.7‰), the meltwater pulses preceding the Younger Dryas did not affect sea-surface salinity off the shelf break. These constraint on the meltwater outflow through the St Lawrence drainage system do not support the triggering mechanism of the Broecker et al. hypothesis2, unless the North Atlantic thermohaline circulation is more sensitive to small salinity changes than most models suggest23.

The effects of temperature and salinity on the aqueous solubility of polynuclear aromatic hydrocarbons

The aqueous solubilities of phenanthrene, anthracene, 2-methylanthracene, 2-ethylanthracene, 1,2-benzanthracene, and benzo(a)pyrene were determined at temperatures ranging from 3.7 to 25.3°C and salinities ranging from 0 to 36.7‰. With the exception of 1,2-benzanthracene, the hydrocarbons experienced salting-out. Their solubilities were insensitive to small changes in salinity and very sensitive to small changes in temperature. On the other hand, 1,2-benzanthracene experienced salting-in, and its solubility was sensitive to small changes in salinity. Potential environmental implications of the data are discussed.

Étude palynologique quantitative dans deux carrières du Crétacé supérieur de la vallée de la Meuse

Abstract. — Quantitative palynological analysis of two profiles in Maastrichtian muddy chalk, distant of about two kilometers, was performed North of Liège in the Meuse valley (Belgium). Spores, pollen grains, Acritarches and Dinoflagellates were investigated. The two profiles are correlated on the basis of the surprising similarity of the relative statistical behaviour of two Hystrichosphaerid groups. The quantitative behaviour of these organisms is paralleled by small fluctuations of the terrigeneous imput. In their turn, these fluctuations are associated with variations in Angiosperm and Conifer pollen contents. Small changes in salinity of sea-water caused by terrigeneous influxes, would account for the quantitative behaviour of the Hystrichosphaerids. Two different sources of the terrigeneous material originate the palynological content of these profiles.

Observations on the Anal Papillæ of Culex (culex) fatigans Wiedemann

THE length and shape of the anal papillae of mosquito larvae, although a useful aid to other diagnostic factors, have never been a critical specific factor. Kettle1 has shown that the length of the anal papillae of Anopheles sergenti Theobald is dependent on the saline content of the larval habitat and that small changes in salinity may produce a large difference in the length of the anal papillae. A similar observation has been noted in Mauritius, where larvae of Culex fatigans Wd. show variation in length of the anal papillae, according to the salinity of their habitat. This variation may be so great and so striking as to cause some doubt as to the immediate identification of the larvae.