Seasonal Variations In Water Temperature Research Articles

The role of interannual environmental variations in the geographic range of spawning and feeding concentrations of redfish Sebastes mentella in the Irminger Sea

Abstract The Irminger Sea is occupied by the most abundant population of the redfish, Sebastes mentella, in the North Atlantic. Results of Russian and international surveys of redfish in the Irminger Sea between 1982 and 2003 are summarized here. Interannual variations in redfish spatial distribution and oceanographic conditions are also analysed. Distribution patterns of spawning and feeding concentrations of redfish are established, and the role of oceanographic factors in the formation of concentrations and in the migrations of redfish are shown. The habitat of the mature redfish population in pelagic waters is confined within the Sub-polar cyclonic Gyre. Redfish spawning grounds extend along the western slope of the Reykjanes Ridge in the areas of intensive rise of intermediate waters. Seasonal variation in water temperature above the ridge slopes is one of the factors causing feeding redfish to migrate westwards, to the central area of the Sub-polar Gyre. Atlantic Water advection, intensified by the Irminger Sea, and water temperature increase in the upper 200-m layer in the second half of the 1990s produced a considerable shift of commercial concentrations of feeding redfish from their usual grounds westwards, to the NAFO Regulatory area.

Behavior of trihalomethanes and haloacetic acids in a drinking water distribution system

This investigation focused on the seasonal variation and spatial fate of chlorination disinfection by-products (CDBPs) in a drinking water distribution system located in a region where very significant seasonal variations in water temperature and surface water quality occur. The analysis of a large number of collected samples showed that the seasonal and geographical variations of both groups of CDBPs under study--trihalomethanes (THMs) and haloacetic acids (HAAs)--were particularly important in this region. THM levels in summer and fall were, on average, about five times higher than in winter, whereas average HAAs in spring were about four times higher than in winter. THMs increased and stabilized in the extremities of the distribution system, whereas HAAs begin to increase, and then decrease (mainly due to a reduction of dichloroacetic acid). This decrease was significantly higher in warm waters than in cold waters, which led to the hypothesis of microbial degradation of HAAs as water approaches the system extremities. In fact, regression models for the occurrence of both CDBPs showed that the residence time of water was one important parameter in explaining the fate of both CDBPs. The spatio-temporal portrait of both groups of CDBPs that was generated demonstrates that, due to their high intra-seasonal changes, the calculation of average annual levels of these substances for compliance with regulations can vary widely. The results used in the portrait of CDBP behavior are also relevant in terms of exposure assessment for future epidemiological studies on human reproductive outcomes in the region.

Sulfur cycling and seagrass (Posidonia oceanica) status in carbonate sediments

Sulfur cycling was investigated in carbonate-rich and iron-poor sediments vegetated with Posidonia oceanica in oligotrophic Mediterranean around Mallorca Island, Spain, to quantify sulfate reduction and pools of sulfide in seagrass sediments. The oxygen penetration depth was low (< 4.5 mm) and sulfate reduction rates were relatively high (0.7–12 mmol m−2d−1). The total pools of reduced sulfides were remarkably low (< 5 mol S m−2) indicating a fast turnover of reduced sulfides in these iron-poor sediments. The sulfate reduction rates were generally higher in vegetated compared to bare sediments possible due to enhanced sedimentation of sestonic material inside the seagrass meadows. The sulfate reduction rates were positively correlated with the seasonal variation in water temperature and negatively correlated with the shoot density indicating that the microbial activity was controlled by temperature and release of oxygen from the roots. The pools of reduced sulfides were low in these iron-poor sediments leading to high oxygen consumption for reoxidation. The sediments were highly anoxic as shown by relatively low oxygen penetration depths (< 4.5 mm) in these low organic sediments. The net shoot recruitment rate was negative in sediments enriched with organic matter, suggesting that organic matter enrichment may be an important factor for seagrass status in these iron-depleted carbonate sediments.

Temperature and salt balances on Georges Bank February–August 1995

Temperature and salinity variability over the crest and southern flank of Georges Bank are investigated using moored observations obtained from February to August 1995 and historical data. There was a large seasonal variation in water temperature, which decreased 1°C–2°C in February to a minimum of 5°C due to surface cooling and wind‐forced cross‐bank advection, and then increased steadily due to surface heating, reaching 10°C (southern flank) to 17°C (crest) in August. The crest warmed more than the southern flank because it is shallower. Temperature variability at shorter timescales (days to weeks) was primarily due to surface heating on the crest and horizontal advection on the southern flank. Salinity variability over the southern flank was primarily associated with two processes. Intrusions of warm, salty, shelf‐slope‐front water in May and August were associated with Gulf Stream warm‐core rings, but did not cause longer‐term changes on the southern flank or penetrate onto the crest. Alongbank advection brought low‐salinity, cool Scotian Shelf Water to the southern flank sites in March and early May, about three weeks after crossing the Northeast Channel onto the northeastern flank of Georges Bank (≈130 km away). This low‐salinity water on the southern flank in the spring did not penetrate immediately onto the crest. Instead, the crest salinity steadily decreased from April to August due to both precipitation (evaporation was small) and, based on historical data, a tidally forced, cross‐frontal exchange flow (0.01–0.02 m s−1) that both freshens and cools the crest.

Environmental controls on the stable isotopic composition of Mercenaria mercenaria: Potential application to paleoenvironmental studies

We have investigated the environmental controls of seasonally resolved records of oxygen and carbon isotopes of modern Mercenaria mercenaria bivalves collected live from five coastal sites along the east coast of North America. Seasonal profiles of δ18O and δ13C obtained by subsampling the incremental growth layers of aragonite were compared with in situ historical records of temperature and salinity. We show that M. mercenaria δ18O profiles track accurately the seasonal variations of water temperature and that variations in growth rates do not affect the shell δ18O values. Growth rates are strongly reduced or interrupted below water temperatures ranging from 8 to 10°C, implying that only bivalves sampled in tropical areas track the full amplitude of seasonal variations. Although further measurements of water δ18O and a better understanding of seasonal variations of the water δ18O‐salinity relationships are necessary, Mercenaria mercenaria bivalves appear to precipitate their shell close to isotopic equilibrium. Whereas the amplitude of the seasonal profiles of δ18O reflects variations in water temperature, the annual average δ18O decreases with latitude, reflecting the trend of rainfall and riverwater δ18O with latitude over the Northern American continent.

Effect of the physiological condition of cyprids and laboratory-mimicked seasonal conditions on the metamorphic successes of Balanus amphitrite Darwin (Cirripedia; Thoracica)

In order to understand the interaction between extrinsic and intrinsic factors on the metamorphic success of Balanus amphitrite cyprids, we investigated the effect of cyprids energy reserves and physiological age (physiological condition of cyprids) on the metamorphic success under five different combinations of water temperature and salinity mimicking different seasons in subtropical Hong Kong: 18 °C/30‰ (winter), 22 °C/34‰ (spring), 28 °C/30‰ (summer), 28 °C/20‰ (rainy season), and 25 °C/32‰ (autumn). The energy reserves of the cyprids were quantified by the ratio of triacylglycerols (TAG) to deoxyribonucleic acid (DNA). The metamorphic success of cyprids was distinctly influenced by their physiological condition and laboratory-mimicked seasons. There was a significant interaction between these factors. In clear contrast to young cyprids with low-TAG/DNA ratio, there was no difference in the metamorphic success of aged cyprids with high-TAG/DNA ratio among seasons. Our results suggest that the physiological condition of cyprids and seasonal variation in water temperature and salinity may jointly determine the metamorphic success of cyprids, and consequently, modulate the population dynamics of B. amphitrite in subtropical waters.

Seasonal acclimation in the photosynthetic and respiratory temperature responses of three submerged freshwater macrophyte species

• Investigations of seasonal temperature acclimation in gas exchange are few and only exist for terrestrial and marine plants. Here we report on results obtained for three freshwater macrophyte species (Callitriche obtusangula, Potamogeton pectinatus and Potamogeton perfoliatus). • We collected plants from the field at monthly intervals and measured photosynthetic and respiratory temperature-response curves. Fitted and calculated parameters were derived from the curves and a simple model was used to evaluate the acclimative capacity to seasonal variation in water temperature. • For all species, optimum temperatures for gross photosynthesis showed little temporal variation. In addition, the shape of the temperature-response curves at suboptimal temperature was not optimized to temporal differences in water temperature. The only consistent seasonal trend in gas exchange was a gradual decrease in photosynthetic and respiratory capacity over time. • Our measurements and model predictions did not point to an acclimative seasonal response in the thermal dependence of oxygen exchange. Hence, we conclude that either other processes constrain the plants' response, or temporal variation in water temperature is less important than seasonal loss of photosynthetic capacity.

Top-down control of population dynamics of the dominant rotifers in two mesotrophic lakes in Hokkaido, Japan.

The effects of abiotic and biotic factors on the population dynamics of rotifers were investigated over two years in mesotrophic Lakes Ohnuma and Konuma (Hokkaido, Japan). Four rotifer species, Polyarthra vulgaris, Trichocerca rousseleti, Keratella cochlearis and Filinia longiseta, dominated rotifer assemblages of both lakes. Their population densities changed seasonally with species-specific trajectories, but these dynamics were not related to seasonal variations in water temperature and dissolved oxygen content. Analysis of the population dynamics revealed that the instantaneous death rate affected the rate of the density change more strongly than the instantaneous birth rate in all dominant rotifer species. The estimated daily ration of predatory rotifers and copepods was higher than the estimated finite death rate of the rotifers in most cases. Effects of food limitation and competition with herbivorous crustaceans seemed to be less important compared to that of the invertebrates predation. These results indicate that in Lakes Ohnuma and Konuma the population dynamics of rotifers were mainly determined by invertebrate predators through top-down control.

Influence of environmental variables on the growth ofLeuciscus cephalus(Linnaeus 1766), in the River Durance, South-east France

mesologic parameters. The chub, Leuciscus cephalus, colonizes the Durance river from its confluence with the Rhone river (alt. 13 m) up to the Serre Poncon dam (alt. 780 m.). The Durance has been exposed to strong human pressure, notably dam construction, reduction of flow rate and perturbation of the natural zonation patterns. The linear growth of chub was studied by scale measurement at six sta­ tions in the Durance catchment area : two of which are located in its main tributaries, the Buech river and the Verdon. An ana­ lysis (ANOVA) of the mean size of fish from one to five years of age shows significant differences between the stations. Principal Component Analysis, in which the stations are characterized by eight nosological variables associated with the density of inver­ tebrates and the number of degree-days above 12° and 22°C established a correlation between chub growth and species habitat, defined in terms of current flow rate, depth and substrate type and temperature. This correlation could be explained in two ways : 1- in slow-flowing homogenous riffle zone, the low water depth and absence of shelters limit the diversity of habitats and the biological richness; nevertheless the abundance of invertebrates does not seem to play an important role ; 2 - in zone of slow flo­ wing riffles subjected to large daily and seasonal variations in water temperature, as in this mediterranean river, temperature might be quite high. Fish older than two years, therefore prefer zones of deep water, where the thermic inertia is stronger.

瀬戸内海の水温・塩分・ｐＨ・栄養塩とクロロフィルａの時間・空間変動

Characteristics of temporal and seasonal variations in water temperature, salinity, pH, nutrient salts and chlorophylla-a in the Seto Inland Sea are described based on the observed data, which were obtained by the automatic observation system installed to a ferry boat operated between Kobe, Japan and Pusan, Korea.

Activity and trapping characteristics in the field of Orchomene nanus (Krøyer) (Amphipoda: Lysianassoidea) at Millport, Scotland

The scavenging lysianassoid Orchomene nanus virtually monopolized catches of amphipods taken in baited traps (using crushed shore crabs Carcinus maenas as bait) deployed in shallow water (5–6 m). Only traps deployed overnight attracted O. nanus. Activity was not associated with any particular time of night. Differences in sub-surface temperature correlated significantly with variation in nightly catch rate (data for May), but this may not reflect a direct causal relationship. A lunar cycle of activity, however, was implicated in May. Trap retention efficiency proved to be high. There was an exponential decline in catch rate with trap elevation above the sea bed. Seasonal variation in catch rate was apparent, with highest catches in late autumn, correlating significantly with seasonal variation in water temperature. Neither the seasonal variation in the duration of darkness, nor the position of the sample day in the lunar cycle influenced seasonal catches significantly.

Aspects of the limnology of Yeppen Yeppen Lagoon, central Queensland

Aspects of the morphometry and physical and chemical limnology of Yeppen Yeppen Lagoon, in tropical Australia, have been investigated. The lagoon is a channel billabong lying in the old bed of the Fitzroy River. It has a relatively small, shallow and elongated basin. Seasonal variations in water temperature, light regime, oxygen concentration, pH and conductivity suggest that the lagoon exhibits a warm monomictic pattern of thermal stratification rather than a continuous warm polymictic one. The annual heat budget was 3294 calories cm-2 year-1. Maximum work of the wind was 238.8 g-cm cm-2, and maximum stability was 34.5 g-cm cm-2. Despite the apparently low stability of stratification, the lagoon remained thermally stratified for much of the year. Analysis of wind-distributed heat suggested that slow mixing was taking place even during periods of relatively high stability, although this mixing was insufficient to reoxygenate the hypolimnion, which remained anoxic for much of the year. Yeppen Yeppen Lagoon is likely to prove eutrophic, and it is suggested that primary productivity will be high because a large volume of the lagoon's water is well lit and a large sediment surface area is in contact with the epilimnion. Notes on the biota of Yeppen Yeppen Lagoon are also given.

EFFECTS OF PRINCE EDWARD ISLAND WATERFOWL IMPOUNDMENTS ON WATER TEMPERATURE

During the summer of 1987 the water temperature was measured at the inlet, at the surface and bottom, and at the outlet of eight man-made impoundments in Prince Edward Island. Surface areas ranged from 0.02 to 1.02 km2. These data provided a basis for evaluating the seasonal variation of water temperature for a relatively dry year. The maximum seasonal temperature difference between the inlet and outlet was 13 °C.Six regression models were developed to estimate maximum seasonal temperature rises and maximum seasonal temperature differences as a function of physical and geometric parameters that are descriptive of the impoundments.

Natural Dynamics of Population Structure and Habitat Use of the Lobster, Homarus americanus, in a Shallow Cove.

We report the results of a nonmanipulative field study of the lobster, Homarus americanus, using long-term behavioral observations of marked individuals. We observed a freely mobile population in an open shallow cove habitat (50 m x 150 m) in Buzzards Bay, Massachusetts. Lobsters larger than 50 mm carapace length (CL) living in or entering the study site were marked individually (334 during the 19-month study). Without further manipulation, the animals were observed as long as they remained in the study site. Of the marked animals, 48% were transient, i.e., seen only once. The population was made up largely of subadults with a sex ratio of M:F = 1.8. The summer and fall resident population consisted of about 30 animals. Maximum residency was over 13 months. Half of the resident population, mostly small animals (50-59 mm CL), apparently overwintered in the site. A distinct peak in molting occurred both years in the spring at a water temperature of about 15°C. Injured animals were seen frequently (26% of the population) including a high proportion of mature resident males missing claws. Most other injured animals were transient (60%). These results suggest that the shallow cove is used as a refuge for injured mature males. Activity was strictly nocturnal with a peak 1-3 h after sunset and declining through the night. Activity levels were equal for both sexes. Overall activity was correlated with seasonal variations in water temperature (0-24°C). At times, activity was correlated more with molting (premolt activity peak) than with temperature. Behavioral interactions in this population are described in a companion paper (Karnofsky et al., 1989).

Life history variation of a freshwater amphipod, Jesogammarus paucisetulosus.

Interpopulational differences in life history features were studied for a stream-inhabiting amphipod, Jesogammarus paucisetulosus. In a population of Mt. Tsukuba, reproduction occurred from winter to late spring, and almost all adults died by August. The smallest body length was 6.5 mm for mature males and 5.0 mm for mature females in early winter. They grew during the breeding season. The rate of ovigerous females was high from February to May (>78%). The rate of paired females was also high in that period, and usually became higher as moulting (oviposition) drew nearer in a reproductive cycle. A rearing experiment showed that clutch intervals were 50, 34 and 20 days at 6, 11 and 17°C, respectively. From the field and experimental data, the number of clutches per female was estimated to be about three. On the other hand, reproduction occurred throughout the year in Mito City, probably because of a little seasonal variation of water temperature. The population always consisted of individuals of different ages, and the life history was semi- annual. The mean body length of breeding individuals was smaller than that in the population of Mt. Tsukuba for both males and females. The smallest size of mature individuals varied seasonally, and the seasonal pattern differed between the sexes. The rate of ovigerous and paired females varied seasonally, and decreased in summer.

Chemistry and Fate of Al(III) in Treated Drinking Water

In order to better understand the processes that affect the chemistry and transport of residual Al, solutions were monitored prior to and following water treatment. The use of alum increased the total Al concentration from 0.37±0.33μmol⋅L-1 in raw water to 1.8±0.33μmol⋅L-1 in filtered water. Approximately 11% of the Al input (raw water and alum) was not retained during treatment, and this residual Al was conservatively transported throughout the distribution system. The treated water contained only a small amount (0.26±0.26μmol⋅L-1) of particulate Al. Of the remaining Al (1.5±0.33μmol⋅L-1), 29% was associated with organic matter (0.44±0.30μmol⋅L-1), 52% was present as monomeric alumino‐hydroxide complexes (0.81±0.37μmol⋅L-1), and 19% was complexed with F 0.30±0.15μmol⋅L-1). Results indicate that chemical addition associated with water treatment (e.g., fluoridation, H2SO4 addition) and seasonal variations in water temperature were largely responsible for changes in the speciation of Al.

Seasonal variations of water temperature and salinity in Osaka Bay

The characteristics of seasonal variations of water temperature, salinity and density in the upper, middle and lower layers in Osaka Bay are described. Osaka Bay is considered to be an estuary, because the weak mixed state appears in spring and summer and the moderate mixed state in autumn and winter. Osaka Bay is divided into three areas, the eastern shallow area that has a large amplitude of seasonal variation of water temperature and low average salinity, the southwestern deep area which has small amplitude of seasonal variation of water temperature and high average salinity, and the northwestern deep area, which has small amplitude of seasonal variation of water temperature and low average salinity.

Distribution, Abundance, and Reproductive Success in the Coral Reef Fish Acanthochromis polyacanthus

The relationships between population density, adult size, and various reproductive parameters (including summed reproductive effort and reproductive success) were examined for the planktivorous coral reef fish Acanthochromis polyacanthus. Data were based on multiple censuses conducted over a 2—yr period on One Tree Reef (southern Great Barrier Reef), at 10 sites that cover the range of habitats occupied by the species. Although several reproductive parameters varied significantly over this habitat range, between—site differences in mean reproductive effort per pair were not significant, and mean reproductive success per pair were significantly reduced at only 2 of the 10 sites. Multivariate analysis suggested that heterogeneity among sites in the mean number of broods produced per pair per spawning season is the major determinant of between—site differences in reproductive success, alone accounting for 69% of the among—site variance in reproductive success in 1979—1980, and 67% in 1980—1981. Principal components analysis of nine apparently independent population and fitness parameters over the 10 sites indicates 82.9% of the communal variance can be accounted for by three orthogonal source variables. These appear to relate to food availability, rates of predation, and, most likely, seasonal variation in water temperature. Results are consistent, overall, with the hypothesis that local populations of A. polyacanthus are equilibrial and resource limited. If this hypothesis is correct, adult density is a valid index of habitat quality. Theoretical considerations suggest that this is not likely to be true for most other small, site—attached species of reef fishes.

Annual cycles of growth, feeding rate, gross conversion efficiency and hematocrit levels of sea bass ( Dicentrarchus labrax L.) adapted to two different osmotic media

Annual cycles of growth, feeding rate, gross conversion efficiency and hematocrit levels are described in sea bass ( Dicentrarchus labrax L.) both in animals adapted to sea water (salinity 37.8‰) and to well water of low salinity (3.5‰). Specific growth rate followed the seasonal variations of water temperature in both media but with a very important exception during the summer. Specific growth rate and daily food intake showed a linear relationship. The differences in gross conversion efficiency, hematocrit levels and the condition of the fish were observed throughout the year and are discussed in relation to salinity, temperature, photoperiod and sexual condition. A practical application for culture of the species in relation to salinity is suggested.

Chemical and Microbiological Processes as Regulators of the Exchange of Substances between Sediments and Water in Shallow Eutrophic Lakes

AbstractIt is generally believed that excessive P release from lake sediments, i. e. internal P load, is only a problem in deep lakes with stagnant anaerobic bottom waters. However, substantial amounts of P can also be released from sediments in shallow, well‐mixed lakes. The dynamics and magnitude of P release from sediments in these types of lakes are affected primarily by physical factors, such as seasonal variations in water temperature and year‐to‐year differences in water renewal. These factors, in turn, induce chemical and microbiological processes which regulate the exchange of substances between sediments and water. The fractional distribution of sedimentary P and the chelating capacity of the water are also important factors that can provide insights to the processes involved and their quantitative impact on the P status in shallow, eutrophic lakes.