Spring Water Temperature Research Articles

Climate-induced warming imposes a threat to north European spring ecosystems.

Interest in climate change effects on groundwater has increased dramatically during the last decade. The mechanisms of climate-related groundwater depletion have been thoroughly reviewed, but the influence of global warming on groundwater-dependent ecosystems (GDEs) remains poorly known. Here we report long-term water temperature trends in 66 northern European cold-water springs. A vast majority of the springs (82%) exhibited a significant increase in water temperature during 1968-2012. Mean spring water temperatures were closely related to regional air temperature and global radiative forcing of the corresponding year. Based on three alternative climate scenarios representing low (RCP2.6), intermediate (RCP6) and high-emission scenarios (RCP8.5), we estimate that increase in mean spring water temperature in the region is likely to range from 0.67°C (RCP2.6) to 5.94°C (RCP8.5) by 2086. According to the worst-case scenario, water temperature of these originally cold-water ecosystems (regional mean in the late 1970s: 4.7°C) may exceed 12°C by the end of this century. We used bryophyte and macroinvertebrate species data from Finnish springs and spring-fed streams to assess ecological impacts of the predicted warming. An increase in spring water temperature by several degrees will likely have substantial biodiversity impacts, causing regional extinction of native, cold-stenothermal spring specialists, whereas species diversity of headwater generalists is likely to increase. Even a slight (by 1°C) increase in water temperature may eliminate endemic spring species, thus altering bryophyte and macroinvertebrate assemblages of spring-fed streams. Climate change-induced warming of northern regions may thus alter species composition of the spring biota and cause regional homogenization of biodiversity in headwater ecosystems.

Effect of the North Atlantic Oscillation on the Thermal Characteristics of Lakes in Poland

This paper presents the effect of the North Atlantic Oscillation (NAO) on the thermal characteristics of lakes in Poland. In the analysis, the use was made of monthly air temperatures recorded at fifteen meteorological stations, water temperatures of twelve lakes, and Hurrell’s winter NAO indices. Over the study period (1971–2010), there was a marked increase in the temperatures of both, air and lake waters. Depending on the NAO phase, water temperatures were observed to depart from mean values, being markedly higher than average (even by 1°C) in the positive winter NAO phase. The differences in water temperatures were statistically significant in the winter-spring season. In turn, in the negative NAODJFM phase lake water temperatures in winter and spring were markedly lower than average (in March even by 1.0°C). The unique response of some lakes depends on their morphometric parameters, including their mean depth.

Activation of AMP-activated protein kinase in response to temperature elevation shows seasonal variation in the zebra mussel, Dreissena polymorpha

Global climate change is affecting ectothermic species, and a variety of studies are needed on thermal tolerances, especially from cellular and physiological perspectives. This study utilized AMP-activated protein kinase (AMPK), a key regulator of cellular energy levels, to examine the effects of high water temperatures on zebra mussel (Dreissena polymorpha) physiology. During heating, AMPK activity increased as water temperature increased to a point, and maximum AMPK activity was detected at high, but sublethal, water temperatures. This pattern varied with season, suggesting that cellular mechanisms of seasonal thermal acclimatization affect basic metabolic processes during sublethal heat stress. There was a greater seasonal variation in the water temperature at which maximum AMPK activity was measured than in lethal water temperature. Furthermore, baseline AMPK activity varied significantly across seasons, most likely reflecting altered metabolic states during times of growth and reproduction. In addition, when summer-collected mussels were lab-acclimated to winter and spring water temperatures, patterns of heat stress mirrored those of field-collected animals. These data suggest that water temperature is the main driver of the seasonal variation in physiology. This study concluded that AMPK activity, which reflects changes in energy supply and demand during heat stress, can serve as a sensitive and early indicator of temperature stress in mussels.

Freshwater green algal biofouling of boats in the Kabul River, Pakistan

AbstractFreshwater green algal biofouling of boats refers to the accrual of freshwater green algae on boats immersed in water. The current research focused on the morphological characteristics of the isolates, species ecology, and the physicochemical properties of the water at the sampling sites. Two localities, Haji Zai and Sardaryab, were sampled at the Kabul River in the district of Charsadda, Pakistan. Freshwater green algae causing biofouling were isolated from the boats. A total of three genera: Cladophora, Rhizoclonium, and Spirogyra with fifteen species belonging to the families Cladophoraceae and Zygnemataceae were observed. Statistical analysis reveals significant stimulation of green algal species in the boats’ fouled communities by increases in water temperature, conductivity, and Total Suspended Solids (TSS). The algal growth at the Haji Zai site is suppressed by TDS in autumn (Pearson −0.56) and is stimulated by water temperature in spring (Pearson 0.44). At the Sardaryab site, algae were stimulated in spring by pH of water (Pearson 0.61), and suppressed by Total Dissolved Solids (TDS) in autumn (Pearson −0.43). Statistical analysis indicates that pH, conductivity, and temperature are the main factors determining the algal biofouling in the Kabul River.

Spring phytoplankton and periphyton composition: case study from a thermally abnormal lakes in Western Poland

Abstract Getting to know the response of different groups of aquatic organisms tested in altered thermal environments to environmental conditions makes it possible to understand processes of adaptation and limitation factors such as temperature and light. Field sites were located in three thermally abnormal lakes (cooling system of power plants), in eastern part of Wielkopolska region (western Poland): Pątnowskie, Wąsosko-Mikorzyńskie and Licheńskie. Water temperatures of these lakes do not fall below 10°C throughout the year, and the surface water temperature in spring is about 20˚C. In this study, we investigated the species structure of the spring phytoplankton community in a temperature gradient and analyzed diversity of periphyton collected from alien species (Vallisneria spiralis) and stones. 94 taxa belonging to 56 genera of algae (including phytoplankton and periphyton) were determined. The highest number of algae species were observed among Chlorophyta (49), Bacillariophyceae (34) and Cyanobacteria (6). In spite of important differences in temperature in the investigated lakes, taxonomic composition of phytoplankton was comparable. Thermophilic species: Glochidinium penardiforme and Cylindrospermopsis raciborskii were found in the species structure (blooms were not observed). The obtained data also showed that the biotic surface of Vallisneria spiralis was a better substrate for Bacillariophyceae colonization than stones. The examination in the spring season of these thermally altered lakes, indicated the taxonomic composition of phytoplankton typical for eutrophic reservoirs (not heated). There was no replacement of any phytoplankton groups which are characteristic for spring conditions, even if there were changes in the competition dynamics.

Impact of extreme climate and bioinvasion on temporal coupling of spring herring (Clupea harengus m.) larvae and their prey

We used weekly observational data from mid-May to end of July in 1958–2012 in Gulf of Riga to investigate temporal coupling between spring herring larvae and their first prey – copepod nauplii, under the extreme hydroclimatic conditions. We focused on a small shallow estuary that is important nursery ground for larvae of the Gulf of Riga (Baltic Sea) herring population. We quantified the effect of extreme values of the winter air temperatures, time of ice retreat and spring water temperatures on the timing of peak abundance of herring larvae and copepod nauplii. We also assessed whether the invasion of the non-native cladoceran Cercopagis pengoi had notable effect on timing and abundance of copepod nauplii during the peak occurrence of herring larvae. In the years of earliest ice retreat the peak abundance of herring larvae was five weeks earlier than in the years of latest ice retreat, while the timing of nauplii remained unchanged. Abundant presence of the C. pengoi affected neither timing nor maximum abundance of copepod nauplii during the herring larvae first feeding period. Thus, we conclude that processes induced by climate variability are superior to invasion of C. pengoi in determining the timing and coupling of larval herring and copepod nauplii.

Inter‐annual variability in the effects of riparian woodland on micro‐climate, energy exchanges and water temperature of an upland Scottish stream

AbstractThe influence of riparian woodland on stream temperature, micro‐climate and energy exchange was investigated over seven calendar years. Continuous data were collected from two reaches of the Girnock Burn (a tributary of the Aberdeenshire Dee, Scotland) with contrasting land use characteristics: (1) semi‐natural riparian forest and (2) open moorland. In the moorland reach, wind speed and energy fluxes (especially net radiation, latent heat and sensible heat) varied considerably between years because of variable riparian micro‐climate coupled strongly to prevailing meteorological conditions. In the forested reach, riparian vegetation sheltered the stream from meteorological conditions that produced a moderated micro‐climate and thus energy exchange conditions, which were relatively stable between years. Net energy gains (losses) in spring and summer (autumn and winter) were typically greater in the moorland than the forest. However, when particularly high latent heat loss or low net radiation gain occurred in the moorland, net energy gain (loss) was less than that in the forest during the spring and summer (autumn and winter) months. Spring and summer water temperature was typically cooler in the forest and characterised by less inter‐annual variability due to reduced, more inter‐annually stable energy gain in the forested reach. The effect of riparian vegetation on autumn and winter water temperature dynamics was less clear because of the confounding effects of reach‐scale inflows of thermally stable groundwater in the moorland reach, which strongly influenced the local heat budget. These findings provide new insights as to the hydrometeorological conditions under which semi‐natural riparian forest may be effective in mitigating river thermal variability, notably peaks, under present and future climates. © 2014 The Authors. Hydrological Processes published by John Wiley & Sons Ltd.

Origin and palaeo-environmental significance of the Berrazales carbonate spring deposit, North of Gran Canaria Island, Spain

The Berrazales carbonate spring deposit is a small outcrop constituted mainly by cascade-like geometries. Four main facies have been identified: fibrous dense macrocrystalline formed by rapid degassing under high-flow conditions; framestones of coated plant moulds formed in moderate energy flow favoured by the presence of biogenic support; micrite/microsparite are primary precipitates in which crystalline aggregates nucleated on organic filaments and/or EPS; banded micrite-coarse crystalline were the result of alternating physically, chemically and biologically induced precipitation in areas of varying flow-velocities. Most facies underwent different degrees of micritization processes. Micrite is distributed as thin lines penetrating the crystals, as irregular patches or as micrite layers. In the first case organic filaments penetrate crystals, suggesting that micritization is mainly biogenically driven. In the latter cases micritization is caused mostly by partial dissolution. Microbe participation in micrite formation increased micrite MgCO3 content in comparison with coarse crystalline facies.Isotopic analyses show positive δ13C values (+2.63 and +4.29‰ VPDB) and negative δ18O (−5.65 and −4.48‰ VPDB) values. Positive δ13C values clearly indicate “deep-sourced” fluids.The Berrazales spring deposit studied here very probably is a small part of a larger carbonate building that was largely eroded by fluvial incision. Calculations of spring water temperature give a range from 20°C to 35°C, characteristic of a cold to warm spring favouring precipitation of calcite and important biogenic activity (framestones). Although the study deposit has textural characteristics of tufas, proving that the CO2 sourced from deep fluids, it should be considered as thermogene travertine, being one more example of the difficulty of using those terms for ancient sedimentary deposits. Carbonate spring deposits, very rare in the Canary Islands, are good archives of recent volcanic activity, fluvial processes and vegetation regimes prevailing in the islands in recent times.

Geochemical evidence for active tropical serpentinization in the Santa Elena Ophiolite, Costa Rica: An analog of a humid early Earth?

AbstractSerpentinization is a planetary process that has important consequences on geochemical cycles, supporting microbial activity through the formation of H2 and CH4 and having the potential to sequester atmospheric CO2. We present geochemical evidence of active serpentinization in the Santa Elena Ophiolite, Costa Rica which is sustained by peridotites with a degree of serpentinization less than 50% with no evidence of an internal heat source. Average spring water temperatures are 29.1°C. Two hyperalkaline spring systems were discovered, with a spring fluid pH up to 11.18. The fluids are characterized by low Mg (1.0–5.9 mg/L) and K (1.0–5.5 mg/L) and relative high Ca (29–167 mg/L), Na (16–27 mg/L), Cl (26–29 mg/L), hydroxide (41–63 mg/L), and carbonate (31–49 mg/L). Active CH4 (24.3% v/v) vents coupled with carbonate deposits ( ; ) also provide evidence for active serpentinization and carbonation. Isotope ratios of the alkaline fluids (δ18O = −7.9‰, δ2H = −51.4‰) and groundwater (δ18O = −7.6‰; δ2H = −48.0‰) suggests that, during base flow recession, springs are fed by groundwater circulation. Methanogenic Archaea, which comprises a relatively high percentage of the 16S rRNA gene tag sequences, suggests that biological methanogenesis may play a significant role in the system. Santa Elena's extreme varying weather results in a scenario that could be of significant importance for (a) improving the knowledge of conditions on a humid early Earth or Mars that had periodic changes in water supply, (b) revealing new insights on serpentinizing solute transport, and (c) modeling hydrogeochemical responses as a function of recharge.

Hidrogeologia do norte da Serra de Chiapas, México: modelo concetual baseado na caraterização geoquímica de nascentes cársicas salobras ricas em sulfuretos

Conspicuous sulfide-rich karst springs flow from Cretaceous carbonates in northern Sierra de Chiapas, Mexico. This is a geologically complex, tropical karst area. The physical, geologic, hydrologic and chemical attributes of these springs were determined and integrated into a conceptual hydrogeologic model. A meteoric source and a recharge elevation below 1,500 m are estimated from the spring-water isotopic signature regardless of their chemical composition. Brackish spring water flows at a maximum depth of 2,000 m, as inferred from similar chemical attributes to the produced water from a nearby oil well. Oil reservoirs may be found at depths below 2,000 m. Three subsurface environments or aquifers are identified based on the B, Li+, K+ and SiO2 concentrations, spring water temperatures, and CO2 pressures. There is mixing between these aquifers. The aquifer designated Local is shallow and contains potable water vulnerable to pollution. The aquifer named Northern receives some brackish produced water. The composition of the Southern aquifer is influenced by halite dissolution enhanced at fault detachment surfaces. Epigenic speleogenesis is associated with the Local springs. In contrast, hypogenic speleogenesis is associated with the brackish sulfidic springs from the Northern and the Southern environments.

Threshold behavior of karst aquifers: the example of the Lurbach karst system (Austria)

Threshold behavior in hydrological systems generally involves a qualitative change of a single process, the system response or the functioning of the system. Different types of thresholds and their underlying controls are examined using the example of the Lurbach karst system (Austria). This karst system receives allogenic recharge from the sinking stream Lurbach, which under low-flow conditions only resurges at the Hammerbach spring. Yet, under medium- to high-flow conditions an overflow toward another spring, the Schmelzbach outlet occurs. Thresholds in physicochemical spring responses and their underlying controls are identified from the analysis of heat and solute transport processes in karst conduits. Applying this concept to the Hammerbach spring suggests that the threshold controlling the response of the spring water temperature was changed in the time period from 2006 to 2009 relative to the years before. At the same time, changes are observed in the behavior of the spring hydrograph and the discharge threshold at which the overflow to the Schmelzbach system is activated. All of these observations can be consistently explained by a decreased diameter of the conduit pathways within the indicated time period, presumably caused by the redistribution of sediments due to a flood event in 2005. Thus, thresholds in the physicochemical spring response were successfully employed to support the identification of a change in the functioning of the Lurbach karst system, which occurred possibly because a threshold related to the sediment transport within the karst conduits was crossed.

Global warming and urbanization affect springwater temperatures in Tokyo, Japan

Due to global warming and urbanization, air temperature in Tokyo has risen 1.6 degrees in the past 30-40 years which has also affected springwater temperatures. From 2005, we have proceeded with the observations of springs in Tokyo metropolis, Japan which had been conducted by Environment of Tokyo from the end of the 1980s to 2001. In the rainy season (October) and dry season (February), we have observed springwater temperatures in 25 springs. The field surveys have revealed that most springwater temperatures has steadly risen in the past 30 years. As of February 2013, water temperatures of 19/11 springs have risen with 5% level in the rainy/dry season. As of February 2006, water temperatures of 10/13 springs have risen with 5% level in the rainy/dry season, i.e., 9/2 springs have acquired/lost the significance as of February 2013. One possible reason is the recent hot summer/cold winter in Tokyo.

Climate Change, Migration Phenology, and Fisheries Management Interact with Unanticipated Consequences

AbstractAccumulating evidence indicates that as global temperatures rise, reproductive behaviors, including migrations, are occurring earlier across a range of taxa. Alone, these changes are ecologically important; however, for some fish populations, management practices may unknowingly interact with climate‐induced changes in reproductive phenology, leading to unanticipated changes in fishing mortality. The potential for such an interaction exists for the Chesapeake Bay Striped Bass Morone saxatilis fishery, which opens on the same week each year during the spawning season. Earlier migrants spawn before the fishery opens; however, later migrants are vulnerable to fishing before they reach the spawning grounds. Consequently, if there are climate‐induced changes in Striped Bass spawning phenology, unexpected levels of fishing mortality may occur for egg‐bearing, prespawn females. To evaluate the potential consequences of this temporally fixed fishing season, we analyzed a time series of gill‐net catch data using an inference‐based modeling approach to identify the environmental cues driving variation in the migratory timing of Striped Bass onto their two primary spawning grounds. We hypothesized that factors driving migratory timing would also influence the proportion of egg‐bearing, prespawn females caught in the fishery each year. Results indicated that spring water temperature was the primary factor influencing the timing of movement onto spawning grounds, with higher temperatures resulting in early migrations. Importantly, our results indicated that in cool years, when females moved onto the spawning grounds later, more egg‐bearing females were caught in the fishery before they could spawn. This situation provides impetus for establishing management approaches that reduce potential climate‐induced variability in fishing mortality in the Chesapeake Bay and fisheries around the globe.Received December 20, 2012; accepted September 5, 2013Published online February 10, 2014

Geochemical Monitoring Along the Türkoğlu (Kahramanmaraş)-Gölbaşı (Adıyaman) Segments of the East Anatolian Fault System

We revisited the historical and instrumental period records and recognized that due to Golbasi-Turkoglu and Turkoglu-Antakya segments of the East Anatolian Fault System (EAFS), densely populated Kahramanmaras district is at great seismic risk. Therefore, in this study, Golbasi-Turkoglu segment of East Anatolian Fault was continuously monitored by collecting data of different geochemical parameters of spring waters emanating from major fault segments (pH, temperature, conductivity, anion and cation concentrations) and correlating with seismicity. For this purpose, three online spring water observation stations located on the Golbasi-Turkoglu segment of EAFS which is the most important source of earthquakes for Kahramanmaras and its surroundings were established. Physical and chemical changes of the spring waters which are thought to be directly related to the fault were monitored. Spring water temperature and electrical conductivity and pH were measured on an hourly basis, whereas anion-cation concentrations were determined daily from bottled spring water samples. Dense seismology network run under the TURDEP Project (EOS Transactions, 88, 333–334, 2007) in the area provided means for monitoring earthquakes down to magnitude 1. We show that a magnitude 4.2 event (20 August 2008) caused significant changes in the geochemical parameters of a nearby spring. From the geochemical transients determined we conclude that there is a close relation between earthquakes and geochemical parameters of spring waters in the region. In order to see this correlation better, measurements of geochemical parameters should continue in the future.

Influence of abiotic factors on invasive behaviour of alien speciesElodea nuttalliiin the Drava River (Slovenia)

The alien and potentially invasive species Elodea nuttallii was observed for the first time in Slovenia's Drava River in 2007, when its huge biomasses were observed at some locations. Changes in biomass of submerged macrophyte communities and abiotic factors such as water temperature, discharge and level were monitored at two impoundments of the Drava River (2009, 2010 and 2011). The correlations between abiotic factors and developed final biomass were assessed to determine if the level of abiotic factors has an impact on the final biomass and invasive behaviour of E. nuttallii. The results obtained showed that biomass of E. nuttallii was not excessive in 2009 and 2010, while in the year 2011 it developed huge biomass at locations, which were not directly exposed to the main water current. The biomass of Myriophyllum spicatum was also higher in 2011 in comparison with 2009 and 2010 but not in such high degree. The key factor for the development of the final biomass of E. nuttallii was the water temperatures in winter and spring and also the point at which water temperatures in spring surpassed 10 xC. The invasive behaviour of E. nuttallii is expected in the years with higher temperatures in January and March and at the locations which are not directly exposed to the main water current. We assume that continuation of the deposition of silt in the impoundments of the Drava River could contribute to invasive behaviour of species E. nuttallii in the years with mild winters and warmer springs.

Dissolved oxygen fluctuations in karst spring flow and implications for endemic species: Barton Springs, Edwards aquifer, Texas, USA

• Concentrations of dissolved oxygen ( DO ) in a karst spring fluctuated by a factor of 2. • DO was modeled as a function of spring discharge and spring-water temperature ( T ). • An increase in T could lower DO to levels toxic to an endemic salamander. Karst aquifers and springs provide the dissolved oxygen critical for survival of endemic stygophiles worldwide, but little is known about fluctuations of dissolved oxygen concentrations ( DO ) and factors that control those concentrations. We investigated temporal variation in DO at Barton Springs, Austin, Texas, USA. During 2006–2012, DO fluctuated by as much as a factor of 2, and at some periods decreased to concentrations that adversely affect the Barton Springs salamander ( Eurycea sorosum ) (⩽4.4 mg/L), a federally listed endangered species endemic to Barton Springs. DO was lowest (⩽4.4 mg/L) when discharge was low (⩽1 m 3 /s) and spring water temperature was >21 °C, although not at a maximum; the minimum DO recorded was 4.0 mg/L. Relatively low DO (<6 mg/L) also was measured at relatively high discharge (3.2 m 3 /s) and maximum T (22.2 °C). A four-segment linear regression model with daily data for discharge and spring water temperature as explanatory variables provided an excellent fit for mean daily DO (Nash–Sutcliffe coefficient for the validation period of 0.90). DO also fluctuated at short-term timescales in response to storms, and DO measured at 15-min intervals could be simulated with a combination of discharge, spring temperature, and specific conductance as explanatory variables. On the basis of the daily-data regression model, we hypothesize that more frequent low DO corresponding to salamander mortality could result from (i) lower discharge from Barton Springs resulting from increased groundwater withdrawals or decreased recharge as a result of climate change, and (or) (ii) higher groundwater temperature as a result of climate change

Links between ocean properties, ice cover, and plankton dynamics on interannual time scales in the Canadian Arctic Archipelago

[1] A decade of instrumented mooring data from Barrow Strait in the eastern Canadian Arctic Archipelago reveals connections between sea ice, water characteristics, and zooplankton dynamics on interannual time scales. On the North side of the Strait, the timing of breakup is positively related to the timing of freezeup in the previous year and negatively related to spring water temperature. This suggests that an early freezeup insulates the ocean from a cold autumn atmosphere, allowing heat to be retained until spring when it contributes to early sea ice erosion. There is also a very strong negative association between the timing of freezeup and late summer salinity, suggesting that monitoring of salinity in real time could be used to predict freezeup. A zooplankton biomass index derived from acoustic Doppler current profiler echo intensity data is used to demonstrate that on the North side there are also strong connections between early summer water temperature and the start, length, and productivity of the zooplankton growth season. On the South side of the Strait where currents are stronger, the relationships seen on the North side were not observed. But here integrated zooplankton biomass index and measured currents are used to identify interannual variability in the zooplankton biomass being delivered downstream into Lancaster Sound. Also on the South side, two yearlong records of daily fluorescence profiles reveal a large difference in the phytoplankton biomass being delivered downstream between years and demonstrate a strong relationship between the timing of the spring phytoplankton bloom and that of breakup.

Seasonal Water Temperature Variability of Springs From Porous Sediments in Gryżynka Valley, Western Poland

Abstract This paper discusses fluctuations in spring water temperature and its correlation to climate and aquifer characteristics. Data from nine springs in the Gryżynka River catchment (Polish Plain) were taken monthly (November 2005 to October 2010). The springs examined in this study are characterised by significant thermal inertia in contrast to air temperature, that is expressed in small temperature amplitudes that range from 1.3°C to 2.3°C. The average temperature of the springs is about 9°C. The research proved that observed groundwater temperature variations on the surface resulted mainly from atmospheric conditions, especially air temperature. The highest water temperatures (up to 10°C) were observed during late summer and early autumn, and the lowest temperature (7.7°C) was observed at the end of the winter period. The range of spring water temperature variability may reflect amount of water contribution from local water recharge in the spring vicinity.

Identification of Winter Flounder (Pseudopleuronectes americanus) Estuarine Spawning Habitat and Factors Influencing Egg and Larval Distributions

A long-term (2002–2011), spatially robust, ichthyoplankton sampling program conducted in the New York/New Jersey Harbor produced 3,033 epibenthic samples from which the relationships between winter flounder egg and larval distributions and environmental parameters were examined. Variations in water temperature, sediment characteristics, and tidal phase were all significantly associated with egg distributions. Inferences about spawning habitats were based on the presence of early-stage eggs (ES1 and ES2). In the Lower Bay (LB), these habitats were primarily non-channel and characterized by more sandy substrates, averaging 96.5 % sand, 2.3 % silt/clay, 0.2 % total organic carbon (TOC), and shallower water (average depths of 5.3 m) compared to LB non-channel stations without ES1 and ES2 eggs (50.2 % sand, 42.0 % silt/clay, 2.1 % TOC, and 7.9 m depths). Occurrences of all stages of eggs in channels were associated with strong tides and severe cold winter water temperatures. These conditions increase the probability of egg transport from shallow spawning sites through increased vertical mixing (strong tides) and delayed development that prolongs the risk of displacement (cold temperatures). Yolk-sac (YS) and Stage-2 larvae were smaller in 2010 when spring water temperatures were highest. Overall, YS larval size decreased with warmer winters (cumulative degree-days for the month preceding peak YS larval collections, r2 = 0.82, p < 0.05). In all years, YS larvae collected in LB were smaller and Stage-3 larvae collected in channels were larger and possibly older than those from non-channel habitat. Because estuarine winter flounder populations are highly localized, adverse effects experienced during egg and larval stages are likely to propagate resulting in detrimental consequences for the year class in the natal estuary.

東京都内の湧水温の長期変化に関する研究

東京都内の湧水温の長期変化に関する研究