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The physiology and behaviour of fish are strongly affected by ambient water temperature. Physiological traits related to metabolism, such as aerobic scope (AS), can be measured across temperature gradients, and the resulting performance curve reflects the thermal niche that fish can occupy. We measured AS of westslope cutthroat trout (Oncorhynchus clarkii lewisi) at 5, 10, 15, 20, and 22 °C and compared temperature preference (T pref) of the species with non-native brook trout (Salvelinus fontinalis), brown trout (Salmo trutta), and rainbow trout (Oncorhynchus mykiss). Intermittent-flow respirometry experiments demonstrated that metabolic performance of westslope cutthroat trout was optimal at ∼15 °C and decreased substantially beyond this temperature, until lethal temperatures at ∼25 °C. Adjusted T pref across species were comparatively high, ranging from 17.8 to 19.9 °C, with the highest T pref observed for westslope cutthroat trout. Results suggest that although westslope cutthroat trout is considered a cold-water species, they do not prefer or perform as well in cold water (≤10 °C) and thus can occupy a warmer thermal niche than previously thought. The metabolic performance curve (AS) can be used to develop species‐specific thermal criteria to delineate important thermal habitats and guide conservation and recovery actions for westslope cutthroat trout.

This study outfitted wild-caught white seabass (Atractoscion nobilis) with electronic data storage tags (DSTs) to evaluate subsequent movements of adult fish captured along Baja California, Mexico (BC). Cefas G5 DSTs were surgically implanted into 89 wild-caught white seabass ranging in size from 66 to 152 cm TL between La Salina (32.11°N/116.90°W) and San Quintin (30.25°N/115.83°W), BC. Twenty-four tagged individuals (27%) were recaptured between April, 2010 and May, 2017, following a mean time at liberty of 608 days (range = 18–1424 days) and a mean displacement of approximately 125 km (± 173 km; range = 3–720 km) between the point of release and recapture. Tagged white seabass were recaptured between Santa Rosalillita, BC (28.66° N/114.27°W) and Monterey Bay, California (36.65°N/121.86°W), with four individuals reported above the U.S-Mexico border. Collectively, 8547 days of archived data revealed that white seabass spent 95% of the time at depths

Ploidy manipulation, such as triploidy, in farmed oysters has been used as a tool to enhance oyster quality throughout all seasons because triploid oysters allocate less energy to gametogenesis, and therefore are deemed better performers than fertile diploids. Nevertheless, scientific reports describing no differences between ploidies and, in certain conditions, disadvantages of triploids are not uncommon. As the use of triploid oyster seed increases culture cost for growers, consistency in performance of triploids is considered to be an important goal. Thus, research to assess how ploidy affects physiological processes underlying oyster performance is fundamental for the aquaculture industry. This work was undertaken to assess if ploidy-based differences in performance in the two most commonly cultivated commercial species of oyster in the United States, Crassostrea virginica and Crassostrea gigas, are associated with filtration, feeding, and metabolism. To test this hypothesis, biodeposition measurements were made with oysters exposed to ambient water conditions at locations and seasons providing a variety of environmental conditions. Oysters did not show differences in filtration and feeding associated with ploidy, but physiological feeding variables fluctuated with environmental characteristics associated with spatial and seasonal differences. A preliminarily test of the hypothesis that differences in energy metabolism may account for differences in performance among ploidy levels indicates that basal metabolic rates of diploid, triploid, and tetraploid Eastern oysters are not different.

Living crinoids are exclusively passive suspension feeders and benthic as adults. However, in the past they adapted to a broad range of ecological niches. For instance, the stratigraphically important middle Paleozoic scyphocrinoids are hypothesized to have been planktonic, employing their inferred gas-filled globular, chambered structure at the distal end of the stem, the so-called lobolith, as a buoyancy device with the crinoid calyx suspended below it. Here, we evaluate this hypothesis using evidence from skeletal micromorphology and theoretical biomechanical modeling. Lobolith walls are typically composed of ossicles, which are exclusively composed of constructional labyrinthic stereom. In plates from the distal side of the lobolith, this stereom extends into microperforate stereom layer, forming wavy ridges and spines. No microscale adaptations for preventing gas leaks and/or ingress of water (such as internal and external imperforate stereom layers) are known. Furthermore, theoretical calculations suggest that the scyphocrinoid tow-net mode of feeding would have resulted in small relative velocities between the towed filter and the ambient water, thus making it an ineffective passive filter feeder. We suggest that the lobolith of these crinoids acted as a modified holdfast rather than as a floating buoy. Its globular shape and distally positioned microspines served as adaptations for living in unconsolidated sediments, analogous to iceberg- and snowshoe-like strategies used by some mollusks and brachiopods. Like modern isocrinids, scyphocrinoids could have maintained an upright feeding posture by extending the distal portion of the stalk along the bottom. In this recumbent posture, the distal part of the stalk with the lobolith might have functioned as a drag anchor. As a consequence of the ~3-m-long stem, even with this posture, the benthic scyphocrinoids could have risen to the highest epifaunal tier in the Paleozoic.

Coliphage have been proposed as indicators of fecal contamination in recreational waters because they better reflect the persistence of pathogenic viruses in the environment and through wastewater treatment than traditional fecal indicator bacteria. Herein, we conducted a systematic literature search of peer-reviewed publications to identify coliphage density data (somatic and male-specific, or MSC) in raw wastewater and ambient waters. The literature review inclusion criteria included scope, study quality, and data availability. A non-parametric two-stage bootstrap analysis was used to estimate the coliphage distributions in raw wastewater and account for geographic region and season. Additionally, two statistical methodologies were explored for developing coliphage density distributions in ambient waters, to account for the nondetects in the datasets. In raw wastewater, the analysis resulted in seasonal density distributions of somatic coliphage (SC) (mean 6.5 log10 plaque forming units (PFU)/L; 95% confidence interval (CI): 6.2–6.8) and MSC (mean 5.9 log10 PFU/L; 95% CI: 5.5–6.1). In ambient waters, 49% of MSC samples were nondetects, compared with less than 5% for SC. Overall distributional estimates of ambient densities of coliphage were statistically higher for SC than for MSC (mean 3.4 and 1.0 log10 PFU/L, respectively). Distributions of coliphage in raw wastewater and ambient water will be useful for future microbial risk assessments.

To evaluate the ecotoxic potential of industrial effluent, whole effluent toxicity (WET) testing has been successfully introduced in several countries. This method can potentially be used as an effective monitoring measure for ambient water, such as river water. This chapter provides a case study where the WET tests were applied to river water monitoring. The river water quality of nine rivers was evaluated using short-term chronic toxicity tests, using three kinds of freshwater species. Two types of river water were found to have an adverse effect on daphnia reproduction. In case of one of the samples, the cause was salinity. To investigate the toxicity factors in the other two samples collected from the same river, samples were collected along the river, and a simplified WET test with daphnia and a chemical analysis were conducted. Subsequently, the causative substances and a point source were estimated. Following this, the sample from the suspicious point of discharge (i.e., industrial effluent) was collected and analyzed. High concentrations of V and Ni derived from petroleum coke were detected, suggesting that these were the main causes of toxicity of the industrial effluent as well as of river water samples. From the above results, it was shown that the WET test is effective not only for the evaluation of industrial effluent, but also for monitoring the ambient water.

Usually, suspension feeding holothurians are considered as passive suspension feeders because they depend exclusively on ambient water movements. In general, suspension feeders, and in particular passive suspension feeders, have structures (tentacles, tube beet, arms, etc.) that enhance the rate of particle capture by changing the scale of turbulence in the water, in terms of the number of Reynolds. As more long are the filtration structures, more turbulent became the flux.

Because trace elements of otoliths are considered a natural marker capable of recognizing the chemical composition of ambient water and fish migration history, these elements could be potentially used to analyse the movement of reproductive (R) and non-reproductive (NR) mature-sized fish. Supposedly, it is not essential for NR individuals to migrate to rivers for spawning because they do not have developed gonads. To investigate the potential differences in migration history between female R and NR kutum, Rutilus frisii, in the southwest waters of the Caspian Sea, the ratios of Sr, Ba, Mg, Na, K and P to Ca in otoliths (from the core to the edge) were examined using laser ablation-inductively coupled plasma-mass spectrometry. In NR fish, a significant increase in Sr:Ca ratio in the otoliths' growth rings, likely due to greater seawater residency, and an increase in Ba:Ca ratio in the last two rings were observed. Increased Ba:Ca ratio could be due to the movement of NR mature-sized fish to the coastal zones for foraging. Seasonal physiological factors such as gonad maturation and spawning activity are more likely to be involved in differences in the other elemental ratios (Mg, Na, K and P). These results suggest that microchemical analyses of growth rings of otolith can be used as a valuable tool for better understanding the movement pattern of different types of adult fish, which could be completed with data from other methods like tagging.

The ranges of the preferred and avoided temperatures in representatives of Thermocyclops crassus (Fischer, 1853) were determined by the results of experimental testing in a thermogradient aparatus and comparison of the obtained values with field observations of the optimal, pessimal and tolerated temperature conditions of development of these populations in nature. Copepods were sampled from pond located near Borok, Yaroslavl region, Russia (58o02'57'' N; 38o14'56'' E). The ambient water temperature was 15.0°С. Temperature preference was determined by the “chronic” method. The phenology of development of Th. crassus was observed in the field of water bodies in Central and Volga Federal Districts of Russia. The final thermal preferendum (FTP) achievement occurred with an increase in the preferred temperature: when animals were placed at a temperature in the thermal gradient (14.0–15.0°C) that approximated the temperature of the source pond, they moved to warmer water until they chose FTP (26.7°C). Obtained the values of FTP (25–30°C), temperature of normal performance (21–32°C) and pessimal temperatures of 9–20 and 33°С well coincide with numerous field observations for temperature conditions of development of species in northern waterbodies of Holarctic and with the temperatures at which populations of Th. crassus thrive in southern waterbodies of Holarctic and in tropical lakes. It is concluded that, despite the historically long existence of the species in the reservoirs of the temperate climatic zone, the northern populations of Th. crassus retained the temperature responses characteristic of their southern sister populations. And although the species has adapted to life in northern reservoirs at lower temperatures, when it becomes possible to choose, cyclops prefer temperatures above 25°C, which are optimal for southern populations living in tropical waters. These data once again confirm that the horizontal thermal gradient method can be used to infer temperature tolerance of freshwater cyclopoid copepods in nature.

Coliphages are alternative fecal indicators that may be suitable surrogates for viral pathogens, but majority of standard detection methods utilize insufficient volumes for routine detection in environmental waters. We compared three somatic and F+ coliphage methods based on a paired measurement from 1 L samples collected from the Great Lakes (n = 74). Methods include: 1) dead-end hollow fiber ultrafilter with single agar layer (D-HFUF-SAL); 2) modified SAL (M-SAL); and 3) direct membrane filtration (DMF) technique. Overall, D-HFUF-SAL outperformed other methods as it yielded the lowest frequency of non-detects [(ND); 10.8%] and the highest average concentrations of recovered coliphage for positive samples (2.51 ± 1.02 [standard deviation, SD] log10 plaque forming unit/liter (PFU/L) and 0.79 ± 0.71 (SD) log10 PFU/L for somatic and F+, respectively). M-SAL yielded 29.7% ND and average concentrations of 2.26 ± 1.15 (SD) log10 PFU/L (somatic) and 0.59 ± 0.82 (SD) log10 PFU/L (F+). DMF performance was inferior to D-HFUF-SAL and M-SAL methods (ND of 65.6%; average somatic coliphage concentration 1.52 ± 1.32 [SD] log10 PFU/L, no F+ detected), indicating this procedure is unsuitable for 1 L surface water sample volumes. This study represents an important step toward the use of a coliphage method for recreational water quality criteria purposes.

Highlights: • Egg specific gravity vary between areas/subpopulations as an adaptation to salinity. • Egg diameter differ between areas/subpopulations whereas egg dry weight does not. • Habitat suitability for egg survival vary depending on salinity and oxygen conditions. • Egg survival probabilities increased following a major saline water inflow event. Abstract: Vertical distribution of eggs as determined by the egg buoyancy, i.e. the difference in specific gravity between the egg and the ambient water, have profound implications for the reproductive success and hence recruitment in fish. Here variability in egg specific gravity of flounder, Platichthys flesus, was studied along a salinity gradient and by comparing two reproductive strategies, spawning pelagic or demersal eggs. Egg characteristics of 209 egg batches (covering ICES subdivisions (SD) 22–29 in the brackish water Baltic Sea) was used to reveal the significance of egg diameter and egg dry weight for egg specific gravity (ESG), subpopulations, and egg survival probabilities of pelagic eggs following a major saline water inflow event. As an adaptation to salinity, ESG (at 7 °C) differed (p < 0.001) between areas; three subpopulations of flounder with pelagic eggs: 1.0152 ± 0.0021 (mean ± sd) g cm−3 in SD 22, 1.0116 ± 0.0013 g cm−3 in SD 24 and 25, and 1.0096 ± 0.0007 g cm−3 in SD 26 and 28, contrasting to flounder with demersal eggs, 1.0161 ± 0.0008 g cm−3. Egg diameter differed (p < 0.001) between subpopulations; from 1.08 ± 0.06 mm (SD 22) to 1.26 ± 0.06 mm (SD 26 and 28) for pelagic eggs and 1.02 ± 0.04 mm for demersal eggs, whereas egg dry weight was similar; 37.9 ± 5.0 μg (SD 22) and 37.2 ± 3.9 μg (SD 28) for pelagic, and 36.5 ± 6.5 μg for demersal eggs. Both egg diameter and egg dry weight were identified as explanatory variables, explaining 87% of the variation in ESG. ESG changed during ontogeny; a slight decrease initially but an increase prior to hatching. Egg survival probabilities judged by combining ESG and hydrographic data suggested higher egg survival in SD 25 (26 vs 100%) and SD 26 (32 vs 99%) but not in SD 28 (0 and 3%) after the inflow event, i.e. highly fluctuating habitat suitability. The results confirm the significance of ESG for egg survival and show that variability in ESG as and adaptation to salinity is determined mainly by water content manifested as differences in egg diameter; increase in diameter with decreasing salinity for pelagic eggs, and decreased diameter resulting in demersal eggs.

Extensive research has described the behavioral response of fishes to electrofishing, but few investigations have measured the response of frogs. As electricity continues to be used as a tool to conduct frog and other amphibian surveys, and because frogs inhabit many of the same environments where electrofishing surveys are conducted for fish species, documenting the response of frogs to electricity is important. We measured the voltage gradient and power density thresholds that resulted in immobilization of early life stages of American bullfrog, Lithobates catesbeianus, and Southern leopard frog, Lithobates sphenocephalus, for a range of pulse frequencies (15–120 Hz) and ambient water conductivities (250–1,381 μS/cm). Voltage gradients of 0.40–1.00 V/cm at power densities of 58–1,461 μW/cm3 induced immobility. The lowest power densities causing immobilization were at pulse frequencies of 60 and 120 Hz; more power was required at lower frequencies and in water with a higher conductivity.

Polymesoda spp., which represent bivalves in the mangrove ecosystem, inhabit the mangrove forests of the Indo-Pacific region. They tend not to be broadly distributed across zones within the mangrove forest, but are instead typically encountered in the mesozone. We conducted field rearing experiments on four plots which were set across a mangrove forest along the Urauchi River of Iriomote Island, from the seaward to landward sides, over a period of 10 months. We compared the survival rates of clams at these plots with different environment for four months. Salinity was also measured during the study period, and we established a correlation between survival rate and change in salinity of each plot. The survival rate of the plot in the mesozone was 90%, that of two plots which were positioned in the seaward zone of the mesozone was 40%, and that of the plot on the landward side was 0%. In plot 4, the ambient water of the bivalves was fresh water. The salinity of the seaward zone changed rapidly in one day, or the salinity of the ambient water surrounding the bivalves was high for a long period of time. In Plot 3, salinity change was gradual, and the average salinity was lower than in Plots 1 and 2. This study indicates that salinity level affects bivalve survival rate and that area similar the mesozone, where gradual salinity change and average salinity were neither too high nor too low, are suitable for these species.

Physiological mechanisms determining thermal limits in fishes are debated but remain elusive. It has been hypothesised that motor function loss, observed as loss of equilibrium during acute warming, is due to direct thermal effects on brain neuronal function. To test this, we mounted cooling plates on the heads of Atlantic cod (Gadus morhua) and quantified whether local brain cooling increased whole-organism acute upper thermal tolerance. Brain cooling reduced brain temperature by 2–6°C below ambient water temperature and increased thermal tolerance by 0.5 and 0.6°C on average relative to instrumented and uninstrumented controls, respectively, suggesting that direct thermal effects on brain neurons may contribute to setting upper thermal limits in fish. However, the improvement in thermal tolerance with brain cooling was small relative to the difference in brain temperature, demonstrating that other mechanisms (e.g. failure of spinal and peripheral neurons, or muscle) may also contribute to controlling acute thermal tolerance.

Although archival tags have been deployed in Thunnus since the early 1990s, few studies have placed such loggers on the small-size growth stage. In this study, Pacific bluefin tuna (PBT, Thunnus orientalis) 20–26.5 cm in fork length (FL) were fitted with archival tags and released off the southern coastal area of Japan from July to August in 2012, 2013, and 2014. Time-series data on swimming depth, ambient water temperature, and peritoneal cavity temperatures collected at 30-s intervals during 78–144 days were analyzed in 11 age-0 PBT. In August, the age-0 PBT spent 69.5 to 83.4% of their time within the mixed layer at mean temperatures between 27.6 and 28.3 °C, while previous studies reported that PBT with FL > 50 cm in the East China Sea are found most often in zones with temperatures between 14 and 19 °C. The thermal difference between the peritoneal cavity and ambient temperature was less than 1 °C for age-0 PBT in August, indicating that they were not in danger of overheating. The mean daytime swimming depths of age-0 PBT were significantly and positively correlated with the depth of the thermocline, especially from August to October. By focusing their swimming depths around the thermocline, the age-0 PBT potentially maximize the probability of encountering prey. There was a significant correlation between the mean nighttime depth and lunar illumination. The change in vertical distribution with the lunar cycle during nighttime is likely a form of predator avoidance.

The blackeye goby is a protogynous reef fish common to the northeastern Pacific Ocean. While this ubiquitous species has been the focus of numerous studies, there are several aspects of its reproductive ecology that are unknown. By directly quantifying reproduction from digital photographs of blackeye goby nests in the field, this study aimed to determine whether reproductive patterns were linked to 1) lunar phase or 2) ambient water temperature; and 3) whether the behavior of gobies changed when a nearby conspecific had eggs in his nest. At Santa Catalina Island, California, twenty 2.25-m2 artificial reefs were established and stocked with similar numbers and size-distributions of blackeye gobies during the summers of 2012 and 2013. Photographs of nests were taken weekly for ∼3 months each summer. Through analysis of photographs, incubation time was found to be more than 7 days but less than 14 days. Nests, each guarded by one male, contained an average of 8664 eggs, in an area of 43.8 cm2, with...

We examined the removal of resuspended sediments from ambient lake water by the pelagic herbivore, Daphnia pulex, in a short-term field-enclosure experiment during the spring clear-water phase. We assessed Daphnia’s ability to clear the water of suspended sediments by evaluating removal of tripton (detritus and inorganic particles) by Daphnia when ambient water conditions were turbid (>100 NTU) or clear (

As a new type of pollutant, microplastics have attracted widespread attention in recent years. Studies have shown that microplastics can affect the growth of microalgae, but little study has been done on macroalgae. In this paper, the enrichment and the characteristics of microplastics on Ulva prolifera, a green tide species, from the Yellow Sea of China were studied. Our results showed that U. prolifera enriched microplastic with an average abundance of 4603.3 ​± ​1167.2 items kg−1 d. w., which was more than 10,000 times of the microplastics in the ambient water (448.9 ​± ​145.68 items m−3). U. prolifera showed different enrichment capacity for microplastics with different shapes, with foam and film being the dominant shapes. The microplastic trapped by U. prolifera were usually in the size range of 2–5 ​mm and the main polymer types were polystyrenepe (PS) and polyethylene terephthalate (PET). The adsorption mechanism of microplastics on U. prolifera showed that its binding to microplastics was mainly through physical interaction. By salvaging U. prolifera at an amount of roughly 239,000 tons/year, a large amount of microplastics (approximately 35.6 ​tons/year.) can be removed from the Yellow Sea, which obviously plays a role in reducing the pollution of microplastics in the marine environment.

Intersex as the manifestation of testicular oocytes (TO) in male gonochoristic fishes has been used as an indicator of estrogenic exposure. Here we evaluated largemouth bass (Micropterus salmoides) or smallmouth bass (Micropterus dolomieu) form 19 National Wildlife Refuges (NWRs) in the Northeast U.S. inhabiting waters on or near NWR lands for evidence of estrogenic endocrine disruption. Waterbodies sampled included rivers, lakes, impoundments, ponds, and reservoirs. Here we focus on evidence of endocrine disruption in male bass evidenced by gonad histopathology including intersex or abnormal plasma vitellogenin (Vtg) concentrations. During the fall seasons of 2008-2010, we collected male smallmouth bass (n=118) from 12 sites and largemouth bass (n=173) from 27 sites. Intersex in male smallmouth bass was observed at all sites and ranged from 60% to 100%; in male largemouth bass the range was 0-100%. Estrogenicity, as measured using a bioluminescent yeast reporter, was detected above the probable no effects concentration (0.73ng/L) in ambient water samples from 79% of the NWR sites. Additionally, the presence of androgen receptor and glucocorticoid receptor ligands were noted as measured via novel nuclear receptor translocation assays. Mean plasma Vtg was elevated (>0.2mg/ml) in male smallmouth bass at four sites and in male largemouth bass at one site. This is the first reconnaissance survey of this scope conducted on US National Wildlife Refuges. The baseline data collected here provide a necessary benchmark for future monitoring and justify more comprehensive NWR-specific studies.

Polycyclic aromatic hydrocarbons (PAHs) are major drivers of risk at many urban and/or industrialized sediment sites. The US Environmental Protection Agency (USEPA) currently recommends using measurements of 18 parent + 16 groups of alkylated PAHs (PAH-34) to assess the potential for sediment-bound PAHs to impact benthic organisms at these sites. ASTM Method D7363-13 was developed to directly measure low-level sediment porewater PAH concentrations. These concentrations are then compared to ambient water criteria (final chronic values [FCVs]) to assess the potential for impact to benthic organisms. The interlaboratory validation study that was used to finalize ASTM D7363-13 was developed using 24 of the 2-, 3-, and 4-ring PAHs (PAH-24) that are included in the USEPA PAH-34 analyte list. However, it is the responsibility of the user of ASTM Method D7363 to establish a test method to quantify the remaining 10 higher molecular weight PAHs that make up PAH-34. These higher molecular weight PAHs exhibit extremely low saturation solubilities that make their detection difficult in porewater, which has proven difficult to implement in a contract laboratory setting. As a result, commercial laboratories are hesitant to conduct the method on the entire PAH-34 analyte list. This article presents a statistical comparison of the ability of the PAH-24 and PAH-34 porewater results to predict survival of the freshwater amphipod Hyalella azteca, using the original 269 sediment samples used to gain ASTM D7363 Method approval. The statistical analysis shows that the PAH-24 are statistically indistinguishable from the PAH-34 for predicting toxicity. These results indicate that the analysis of freely dissolved porewater PAH-24 is sufficient for making risk-based decisions based on benthic invertebrate toxicity (survival and growth). This reduced target analyte list should result in a cost-saving for stakeholders and broader implementation of the method at PAH-impacted sediment sites. Integr Environ Assess Manag 2016;12:493-499. © 2015 SETAC.

The influence of hatching date on the sex ratio of wild Gnathopogon caerulescens was examined. Cohorts reared from eggs collected in the early and middle parts of the spawning season showed almost balanced sex ratios, with female bias in some cohorts. Cohorts born later in the season mostly displayed male bias, and the mean proportion of males later in the season was significantly higher than in early- and mid-season cohorts. These results indicate that the sex ratio of G. caerulescens changes with the time of breeding, increasing along with the ambient water temperature of the lake.

Elevated water temperature has been shown to influence mortality during fishing tournaments. However, data on water conditions in live wells are lacking, and the benefits of managing live-well temperature are equivocal. The objective of the current study was to define water temperature in a live well during live-release black bass Micropterus spp. angling tournaments, and to compare live-well temperatures with ambient temperatures in the surrounding lake. For this, thermal loggers were added to live wells during three different tournaments (17 live wells across three tournaments), and anglers fished in the tournament using automatic live-well recirculating pumps (recirculation and aeration occurs and freshwater is pumped in). Live wells were found to be significantly cooler (˜1°C) than the epilimnion for two of the three tournaments examined, and 1°C warmer than the epilimnion in the other tournament examined. Based on these findings, fish held in live wells during black bass tournaments do not ap...

+An extensive literature deals with the function of the exposed gill or gill frag ments of suspension-feeding bivalves in transporting water and in retaining and sorting particles suspended in the water (see JA˜rgensen, 1966) . These studies have led to the view that normal feeding results from the largely independent activities performed by the three main ciliary systems on the gill filaments : the lateral cilia transport water, the latero-frontal cirri intercept and retain particles suspended in the water, and the frontal cilia sort and transport retained particles to ciliary tracts along the gill bases or the free margins of the demibranchs. The function of the latero-frontal cirri in straining particles from the water passing through the interfilanientar spaces and in transferring them to the frontal ciliary tracts was studied in the mussel Mytilus edulis by Dral (1967) , who concluded that the intercirral distances, 2—3 @m,determined how small particles could be efficiently retained. Measurements of the efficiency with which Mytilus and other bivalves clear suspended particles from the ambient water showed, however, that even smaller particles could be efficiently retained. The discrepancy between predicted and measured efficiencies of particle retention in Mytilus seemed to vanish when it was observed that the cirri are featherlike struc tures, composed of cilia of different lengths with distal ends branching off from the main stem of the cirrus at regular intervals of about one 1zm (Moore, 1971). It was assumed that these side branches of the cirri form the filter that is responsible for the retention of particles smaller than the intercirral spaces (Moore, 1971; Owen, 1974a, b). However, other suspension feeders that possess gills with short (oysters) or undeveloped (scallops) latero-frontal cirri can also efficiently retain particles (JA˜rgensen and Goldberg, 1953; Haven and Morales-Alamo, 1970; Vahl, 1972a, b, 1973a, b). Moreover, the M'@tilus gill may under circumstances become leaky even to large particles despite apparently normally beating latero-frontal cirri (JA˜rgensen, 1975). It was, therefore, found of interest to examine more closely how exposed gills and isolated gill fragments of various gill types transport water and deal with suspended particles, and especially to compare the efficiency with which particles are retained in relation to the size and function of the latero frontal cirri. Serotonin (5-HT) has been found to act in a cilio-excitatory way on the bivalve gill. It has been assumed that the serotonergic nerves demonstrated in gill fila ments of several bivalves control ciliary activity, especially of the lateral cilia (Aiello, 1960, 1970; Gosselin, 1961; Paparo, 1972; Paparo and Finch, 1972; Stephano and Aiello, 1975). Less is known about the role that serotonergic in nervation may play in controlling the activity of the latero-frontal cirri (or other

Leucocytherella sinensis, a ubiquitous and the most abundant ostracod endemic to the Tibetan Plateau, can account for >98% of the ostracod association. These low-diversity associations are hard to interpret using community palaeoecology alone, but environmentally driven phenotypic variation may provide clues to palaeoenvironmental factors. L. sinensis displays several morphological forms, characterised by different tubercle formation on their valves. These morphological forms were described as diverse species. We present a taxonomical revision and a first description of the soft parts of L. sinensis. We also redescribe the genus and confirm its assignment to the subfamily Limnocytherinae Klie, 1938. Analysis of L. sinensis associations from surface sediments of 12 Tibetan lakes shows a connection between tubercle formation and specific conductivity (SC) of the ambient water with lower tubercle number at higher salinity. Tubercles are less common in low SC populations and highest within the beta-oligohaline range. However, high Ca2+ concentrations suggest a combined effect of salinity and Ca2+ ion concentration on tubercle formation. The phenomenon of tubercle formation can be used to trace salinity changes recorded by fossil L. sinensis valves from Tibetan Holocene lake sediments.

An experiment was conducted to delineate the effect of heat shock and chlorine on the biochemical responses of Labeo rohita spawns for evaluating acquired thermal tolerance. Spawns were equally distributed in three different groups i.e., group 1 heat shock (37 °C) without chlorine, group 2 heat shock (37 °C) in chlorinated water and group 3 control in ambient water (28 °C). Following 1-h stress, the animal was transferred to ambient water conditions to study the recovery from stress at different sampling hours i.e., 0, 2, 4, 8, 14, 24 and 48 h. Stress parameters viz., glucose, lactate dehydrogenase, malate dehydrogenase and adenosine triphosphatase were measured for both the experimental groups and compared with the control. At the end of 48 h, the recovering spawns in the respective experimental groups were subjected to temperature higher than 37 °C in order to check for thermal tolerance and induction of cross protection. Their survivability rates were checked after exposure to 38, 39, 40, 41 and 42 °C. The result indicated that the spawns in group 1 recovered within 24 h wherein heat shock alone imparted higher thermal tolerance in them leading to 100 % survival at 40 °C; however the fishes in group 2 did not recover even after 48 h and demonstrated only 30 % survival at 40 °C. In both experimental groups, none of the fish survived the exposure to 42 °C. The results indicate that the combined effect of heat shock and chlorine has more pronounced effect on L. rohita spawns and fails to develop acquired thermal tolerance.

Tribological mechanism of the diatom frustule with multi-layers of pores is studied with the liquid-solid interaction (FSI) method. Based on the reconstructed representative Coscinodiscus sp. frustule with two-layer porous structure, the tribological performances for the diatom frustule at its different pore diameter ratios, pore depth ratios, and velocities are solved through governing equations involved with FSI method. The numerical result shows that the existence of the two-layer porous structure of the diatom helps to reduce the friction between it and ambient water, and to increase its ability to resist the ambient water pressure. The two-layer porous structure effectively improve the tribological performances for the diatom frustule due to the change in the frustule velocity.

The movement of adult muskellunge, Esox masquinongy Mitchill, has been investigated in a variety of systems, but temperature selection by muskellunge has not been examined where well-oxygenated waters were available over a range of temperatures for much of the year. Thirty subadult and adult muskellunge tagged internally with temperature-sensing radio tags were tracked from March 2010 to March 2011 in a Tennessee reservoir. Mean tag temperatures were 18.9 °C in spring (March to May), 22.1 °C in summer (June to August), 16.5 °C in autumn and 9.8 °C in winter (December to February). When the greatest range in water temperatures was available (7.1–33.3 °C; May to early August 2010), their realised thermal niche (mean ± 1 SD) was 22.3 °C ± 1.8; the realised thermal niche was affected by fish size (smaller fish selected slightly warmer temperatures) but not sex. An electric generating steam plant discharging warm water resumed operation in January 2011, and most (86%) tagged fish occupied the plume where temperatures were ≈10 °C warmer than ambient water temperatures. No mortalities were observed 15 days later when plant operations ceased. Their affinity for the heated plume prompted concerns that muskellunge will be too easily exploited when the plant operates during winter.

Fluctuating water temperatures can affect fitness in fish when the opportunity to select habitats with appropriate temperature is limited. Despite the importance of the relationships between water temperature and host–pathogen interactions, reports on the susceptibility of fish to infectious viruses under conditions of changing water temperature are limited. Here, we compared the survival rates of common carp (Cyprinus carpio) infected with Cyprinid herpesvirus 3 (CyHV-3) in water in which the temperature varied from 22 °C ± 3 °C and in water with a constant temperature of 22 °C or 25 °C. We also examined changes in concentrations of CyHV-3 DNA and cortisol released from infected fish into ambient water as indicators of CyHV-3 transmission and stress response, respectively. The survival rates of fish infected with CyHV-3 were lower, and concentrations of CyHV-3 DNA and cortisol were higher, in the fluctuating-temperature treatments than in the constant-temperature treatments. Our findings provide direct evidence that carp are highly susceptible to CyHV-3 infection when water temperatures change diurnally. Moreover, such temperature fluctuations can promote transmission of CyHV-3 in the wild. Preserving a variety of aquatic environments including water temperature may help to prevent disease outbreaks and to conserve fish populations.

Predation pressure of Noctiluca scintillans on diatoms and thecate dinoflagellates was investigated off the western coast of Kyushu, Japan by a comparison between the taxonomic composition of prey in the food vacuoles of N. scintillans and that in the ambient water. The ratios of total diatoms and centric diatoms in the food vacuoles were higher than those in the ambient water, while thecate dinoflagellates and pennate daitoms showed a reverse trend. These results indicate that predation pressure of N. scintillans on total diatoms is higher than on thecate dinoflagellates, and that the pressure on centric diatoms is stronger than that on pennate ones. Among the centric diatoms, Chaetoceros and Bacteriastrum were dominant in the food vacuoles and their respective ratios were higher than in the ambient water. Their chain-forming colonies with long setae appear to be easily trapped by N. scintillans tentacles and this is probably the cause of the high predation pressure of N. scintillans on centric diatoms., Plankton and Benthos Research, 8(4), pp.186-190; 2014

The effect of salinity and ionic composition of ambient water on the mortality of the Ponto-Caspian gammarid amphipod Dikerogammarus haemobaphes (Eichwald, 1841) was measured in the laboratory and an osmoregulatory curve plotted. A three-day experiment showed that salinities both higher (15, 20 PSU) and lower (0.1, 3.5 PSU) than 7 PSU reduced survival. Salinity levels of 0.1 and 20 PSU were lethal after 20 and 55 h of exposure, respectively. Among the ions analysed (Cl−, , Na+, K+, Ca2+, Mg2+), Cl− and K+, and the ratios of Na+/K+ and Na+/Cl− had the greatest influence on the mortality of D. haemobaphes. Mortality was zero in waters where the concentrations and ratios of these ions most closely resembled those prevailing in the Caspian Sea. The osmoregulatory curve shows that D. haemobaphes is a eurytopic species i.e. osmoregulation is hyperosmotic within the salinity range of 0.1–20 PSU. The results of this study indicate ways in which inherent physiological capabilities affect the ability of an organism...

5 pages, 2 figures, 1 table, The otoliths of John's snapper (Lutjanus johnii) from the Persian Gulf and the Oman Sea were studied to evaluate whether otolith shape can be used to differentiate populations. John's snapper is a relevant commercially exploited species in the Arabian Sea, and the identification of different stocks is a major issue for fishery management. Otolith weight was used to examine the growth rate of both populations and as an indicator of similar ambient water composition. Otolith contours were obtained using wavelet functions, from the finest (WLT 1) to coarsest (WLT 9) scales, and then compared by principal components (PCA) using a canonical discriminant analysis (CDA) for each scale. No significant differences were noted in the otolith weight between the two populations (ANCOVA, P>. 0.05). The variability of the finest scales (WLT 1-3) was very high and showed a low percentage of classification (61%). The intermediate scales (WLT 4-6), and WLT 8 provided the best results; whilst the highest classification percentage was found in WLT 4 and WLT 8 (76% and 77%, respectively). The results of this study enable us to conclude that both populations should be considered separate stocks. © 2014

With ocean warming predicted globally, one of the mechanisms driving distributional shifts and changes in the abundance of resident fishes is reproductive output. The relationship between sea surface temperature and the reproductive activity of a eurythermic, resident coastal species, blacktail seabream Diplodus sargus capensis, was examined in the “ocean warming” hotspot of the northern Benguela. Reproductive activity was found to be restricted to periods when the water temperature dropped below 20 °C. A metadata analysis conducted on the D. sargus sub-species complex similarly showed that reproductive activity was restricted to temperatures between 15 and 20 °C, regardless of the range in ambient water temperature. Based on these findings and using satellite derived SST information, we examined D. s. capensis’s total and seasonal “reproductive scope” that is defined as either the area suitable for spawning each year or the duration of its potential spawning season at a fixed geographical locality, respectively. Trends were examined over the last three decades. Reproductive scope by area was found to be shrinking at a rate of 7 % per decade in southern Angola and expanding at a rate of 6 % per decade in northern Namibia. Reproductive scope by season decreased by 1.05 months per decade in Namibe, southern Angola and increased by 0.76 months per decade in Hentiesbaai, northern Namibia. Changes in reproductive scope may be a driving mechanism of distributional shifts in resident fishes, although the rate of the shifts is likely to be slow. More importantly, changes in reproductive scope will not be uniform throughout fish distributions and will most likely result in heterogeneous variations in fish abundance.

The larvae of catfish, Clarias batrachus (av. wt. 15 ± 2 mg) were exposed to five concentrations of thyroxine (T4) with three feeding regimes. Five media 1.3 mcg L−1 (T-1), 2.2 mcg L−1 (T-2), 3.6 mcg L−1 (T-3), 6.0 mcg L−1 (T-4), 10.0 mcg L−1 (T-5) of T4 and control with three feeding regimes 1 day (once a day), 2 days (twice a day) and 3 days (thrice a day) were maintained in triplicate set in 54, troughs containing 2-L water. The larvae reared in media (T1, T2, T-3, T-4 & T-5) with feeding regimes 1 day, 2 days & 3 days showed 100 % survival which was significantly high (p

We examined the extent to which otolith microstructure provides an accurate estimate of age, growth, and early life history transitions during the period between hatching and 1 week after emergence in Brown Trout Salmo trutta exposed to natural variations in ambient water temperature. All fry analyzed possessed a prominent check on the observed date of hatching. After hatching, daily growth increments were visible on sagittal otoliths. There was no evidence for the formation of an emergence check mark and no statistically significant evidence that emergence and daily temperature fluctuations interacted to form check marks. However, daily temperature fluctuations may influence the formation of check marks, largely based on an observed increase in the proportion of fish possessing checks on the days following the two largest temperature fluctuations observed during the experiment. There was no evidence that feeding or stressing emergent fish contributed to the formation of an emergence check mark. The observed proportionality of somatic and otolith growth in conjunction with daily growth increments and the formation of a prominent hatch mark provides the opportunity to back-calculate somatic length distributions and to document the hatching, dispersal, growth, and survival of the early life history stages of Brown Trout in nature

We determined the δD values of the total fatty acids of Japanese rice to test the hypothesis that there is a wide variation in the hydrogen isotopic composition (δD) of the total fatty acids of Japanese rice sourced from different growth areas in Japan and to distinguish the minor differences among these growth areas. The δD values showed a wide variation ranging from -216‰ (Hokkaido) to -183‰ (Okinawa), indicating a good correlation with the corresponding variations for ambient water (r = 0.63) and mean temperature (r = 0.84). These results suggest that the δD values for the total fatty acids can be representative of the growth environments in Japan.

Exotic animals can cause genetic contamination of indigenous species if they escape and reproduce in wild populations. The loach Misgurnus anguillicaudatus and species related to it have been imported into Japan for commercial use. We collected live loach specimens from the central wholesale market in Tokyo. For the 451 specimens collected, ploidy status was examined by DNA content flow cytometry, and polyploid loaches with triploid, tetraploid, and other higher ploidy ranges were detected. Hypertriploid and hypertetraploid individuals were easily detected by flow cytometry using standard eudiploid, eutriploid, and eutetraploid controls, and the reproductive capacities of these hyperpolyploid males were then examined. Sperm of hypertriploid males did not exhibit active progressive motility, and major populations of spermatozoa or spermatozoon-like cells were detected in the triploid and hexaploid ranges. Motile haploid spermatozoa were very rare in sperm from hypertriploid males. Therefore, hypertriploid males were sterile, whereas hypertetraploid males produced fertile hyperdiploid spermatozoa with active progressive motility after contact with ambient water. Viable progeny occurred in crosses between normal wild-type diploid females and hypertetraploid males, but androgenotes induced by the fertilization of UV-irradiated eggs with the sperm of hypertetraploid males were inviable hyperdiploids. Cytogenetic analyses of those androgenotes indicated that hypertetraploid males should produce hyperdiploid spermatozoa with 2n = 54 (i.e., four supernumerary microchromosomes).

We evaluated the use of hydrogen peroxide (H2O2), temperature, or both, to control mortality presumptively caused by fungus Saprolegnia in Florida largemouth bass Micropterus salmoides floridanus eggs in a flow-through hatchery system. Four treatments—ambient water (AW; control), ambient water and H2O2 (AWHP), heated water (HW), and both heated water and H2O2 (HWHP)—were tested on each of 30 replicate spawns. Four 8 cm × 5 cm sections of spawning mat, one for each treatment, were cut from each of the 30 selected spawns. Egg counts on each cut mat section were recorded. Water temperature in all AW and HW trial tanks ranged from 17.9°C to 19.2°C and from 22.1°C to 23.6°C, respectively, during treatment. The water temperature difference between treatments averaged 4.4°C. Hydrogen peroxide trial tanks received two, 100 mg/L H2O2 treatments 8 h apart, until hatch. The 7.5 L/min incoming water flow was not reduced during treatment. The addition of HW, H2O2, or both, significantly increased mean percent...

article i nfo Article history: Keywords: Triploid Out-of-season Smoltification Photoperiod ATPase Atlantic salmon Production of sterile triploid Atlantic salmon (Salmo salar) would appear to be the best strategy to address the growing concerns on environmental impacts of escapees. However, the industry relies on a year round supply of smolts to ensure continual production and to date the production of out-of-season (S0+) triploid smolts has not been reported. The present study demonstrates that S0+ triploid smolts can be produced using an accelerated "square-wave" photoperiod (LL-LD 9.5:14.5-LL) under ambient water temperature. Such a regime advanced the timing of smoltification by 3 months (S0+) relative to their siblings under an ambient photoperiod (S1+) as observed through body silvering, fin darkening, decrease in condition and significantly increased gill Na + ,K + -ATPase activity. Importantly, triploid S0+ fish smolted 4 weeks earlier than their diploid siblings. In S1+ populations, no difference in smolt time was observed although triploid fish also achieved a higher weight. Furthermore, deformity prevalence was very low during the fresh (≤5%) and seawater (≤2.5%) stages within both ploidies mainly represented by spinal deformity and operculum shortening. Family effects for growth and condition were clear, however, no significant family/ploidy interactions were observed although this was based on only two full-sib crosses. These results are promising but there is still a long way to go before triploid can become a commercial reality. Further studies are required to optimize and refine husbandry protocols, define breeding strategies especially regarding family selection and overall better understand triploid salmon physiology.

Understanding linkages between natal and nursery habitats is critical for conservation of riverine fishes. Scaphirhynchus sturgeons inhabiting the middle Mississippi River may originate from the Missouri or Mississippi rivers, although relative importance of these recruitment sources is unknown. We characterized the relationship between water and sturgeon fin ray Sr:Ca, verified shifts in water Sr:Ca are recorded in age-0 sturgeon fin rays, and determined whether age-0 sturgeons from the Mississippi and Missouri rivers exhibited distinct fin ray Sr:Ca signatures. Fin ray Sr:Ca of laboratory-reared fish reflected transfer from water with elevated Sr:Ca to ambient water 1 day posthatch, indicating that short-term residency in environments can be detected. Nine of 30 age-0 fish captured in the middle Mississippi River were Missouri River emigrants. Four of these emigrants originated in the upper portion of the lower Missouri River (≥589 km upstream from its mouth), where water Sr:Ca is higher compared with the lowermost section of the Missouri River and the Mississippi River. Twenty-five of 30 fish collected from the lowermost section of the Missouri River originated within this river segment; the remainder originated upriver. Fin ray Sr:Ca enables identification of natal river segment for age-0 sturgeons and contributions of river segments to sturgeon recruitment.

A feeding trial was performed to assess the potential beneficial effect of two levels of mannanoligosaccarides (MOS) on the growth performance, feed utilization, hematological parameters, and liver histopathology of gilthead seabream Sparus auratus (also known as gilthead bream). Mannanoligosaccarides were added at the rates of 2 and 4 g/kg to a fish-meal-based control diet, and each diet was given (twice daily [midmorning and midafternoon] to apparent satiation) to triplicate groups of gilthead seabream growers (mean weight = approximately 170 g) in sea cages. The trial lasted 12 weeks, and the average ambient water temperature ranged from 19.6 degrees C to 24.7 degrees C during the experimental period. At the end of the experiment, fish attained market size (350-450 g) and their health status was evaluated by blood analysis and liver histology. There were no differences in survival rates among fish fed experimental diets. However, there were significant improvements in both growth and feed utilization among fish fed diets supplemented with MOS. Hemoglobin (Hb) and hematocrit (Ht) levels and erythrocyte, leukocyte, and thrombocyte (Thr) counts were unaffected by any dietary MOS. The levels of Hb (g/dL; mean +/- SD) and Ht (%; mean +/- SD) were 11.0 +/- 2.5 and 45.6 +/- 6.7 for the control group, 11.1 +/- 1.7 and 39.3 +/- 8.0 for the 2-g/kg group, and 11.2 +/- 1.9 and 40.2 +/- 8.4 for the 4-g/kg group. The mean Thr count ranged from 47.6 to 53.8 x 10(3)/mm3. Despite the apparently higher Thr counts for fish fed diets supplemented with MOS, these differences were not significant. Moreover, no histopathological differences were observed in liver tissue cross sections between control and treatment groups. These results suggest that supplementation of diets with MOS had no significant effects on general fish health.

Seasonal temperature cues may play an important role in the parr–smolt transformation of Pacific salmon Oncorhynchus spp., but salmon reared in groundwater-supplied hatcheries with seasonally stable water temperatures do not experience these cues. In this study, conducted over six release years, hatchery spring Chinook salmon O. tshawytscha that were initially reared in a groundwater-supplied hatchery were transferred to acclimation ponds supplied with surface water either in November (November transfer [NT]) or January (January transfer [JT]) for rearing at ambient water temperatures prior to release into the Umatilla River, Oregon, in early March. After stream release, we monitored out-migration travel times and survival to John Day Dam (JDD) by using passive integrated transponder tags in a subsample of each release group. Across all release groups, median travel time was slower for NT groups (51 d) than for JT groups (46 d); significant differences were observed in five of six release years. ...

Two adult bottlenose dolphins (Tursiops truncatus) were individually housed in aboveground pools over a 10-day period and exposed to decreasing water temperatures to determine whether cold stress activated the hypothalamic-pituitary-adrenal axis. To serve as controls, two additional adult dolphins were similarly housed for the same duration but at ambient water temperatures (16.8-19.6 degrees C). Across all subjects, water temperatures ranged from 4.2 to 19.6 degrees C. Voluntary blood draws were made from each dolphin every 2-3 days, and serum was analyzed via radioimmunoassay for cortisol and aldosterone. Dolphins exposed to cold water showed an increase in serum cortisol and aldosterone as temperature declined; at the coldest water exposure, cortisol was more than three times and aldosterone more than two times the levels measured at ambient temperature. Elevations occurred before the water temperature declined below the individual animal's lower critical temperature, the point at which the metabolic rate increases to compensate for the loss of body heat. Variations in corticosteroids were unrelated to the 10-day isolation period, suggesting that the response was related to the cold stress and not impacted by the isolation. Elevations in cortisol and aldosterone were lower than those observed in force captured and stranded dolphins. Although potentially related to the general adaptive stress response, elevations in cortisol and aldosterone may have other adaptive functions related to mitigating impacts resulting from cold environmental temperatures.

Livewell conditions during competitive angling events are thought to affect fish mortality. We examined the effects of livewell additives on initial and delayed mortality of largemouth bass Micropterus salmoides. We applied three treatments (salt, ice, or salt and ice) to livewells during tournaments conducted on lakes in Illinois, United States, as well as in laboratory and pond experiments designed to examine the effects of fish size and ambient water temperature on mortality. Fish were collected after tournament weigh-in procedures were completed and monitored for delayed mortality every 24 h for 5 d. Initial mortality did not differ among livewell additives during these field experiments. Although delayed mortality was high (35%), it was not significantly different among livewells that contained salt (56%), ice (48%), ice and salt (40%), and controls (30%). Additives administered during the laboratory experiments, at cool water temperatures, resulted in significantly lower delayed mortalities than those observed during the field experiments when ambient water temperatures were warmer. Initial and delayed mortality did not differ among livewell additives during the laboratory experiments. Larger fish in field experiments had significantly greater delayed mortality than smaller fish in the pond experiments even though initial and delayed mortality did not differ among livewell additives. Our results suggest that fish size and ambient water temperature have a greater influence on delayed mortality observed during competitive angling events than the specific livewell additives studied here.

Under optimal conditions, bivalves tend to filter the ambient water at a maximum rate but under suboptimal environmental conditions, including low or very high algal concentrations, the filtration rate is reduced. The upper algal concentration at which the blue mussel,Mytilus edulis, exploits its filtration capacity over an extended period of time was identified by stepwise raising the algal (Rhodomonas salina) concentration in steady-state experiments above the threshold for continuous high filtration rate. The duration time before incipient saturation reduction decreased with increasing algal concentration, and the threshold concentration for incipient saturation reduction of filtration activity was found to be between about 5,000 and 8,000 cells mL−1, equivalent to 6.3 and 10.0 μg chlaL−1, respectively. Reduced filtration rate was related to total number of algal cells ingested previous to incipient saturation and found to be cells. Video-microscope recordings of pseudofaeces production revealed that the trigger threshold concentration for formation of pseudofaeces was about 12,000 cells mL−1. Faeces produced by saturated mussels consisted of closely packed undigested algal cells, indicating severe overloading of the digestive system caused by high algal concentrations which mussels are not evolutionary adapted to cope with.

Discus (Symphysodon discus) maintained in aquaria are held in a wide range of water parameters and subjected to many different feeding regimes. In a pilot study, four groups of discus (mean length 12.1 cm, mean weight 57.3 g) were submitted to a radiographic examination to assess the skeletal structure of the vertebral column under defined environmental conditions. Water temperature was 30°C for all groups. Two groups were held at

Pacific bluefin tuna Thunnus orientalis has 2 spawning grounds with different spawning seasons. One is in the northwest region of the Philippine Sea during May to June and the other is in the Japan Sea from late July to August. The oxygen isotope level in otoliths is affected by water oxygen isotope composition and negatively correlated to the ambient water temperature. We developed a technique using the temporal profiles of otolith δ18O to discriminate the natal origin of Pacific bluefin tuna. For Age-0 tuna caught in the Japan Sea (n = 35), the δ18O values varied from –2.5 to –2.2‰ between the otolith core and a distance of ca. 600 μm from the core, and then the values increased (enriched) to about –0.8 to –1‰ at 700 to 1000 μm. For Age-0 tuna caught in the Pacific Ocean (n = 41), the otolith δ18O values varied between –2.8 and –2.2‰ at 0 to 1000 μm from the otolith core and then increased to ca. –1.5 to –1‰ at around 1200 to 1600 μm from the core. The different profiles of otolith δ18O values between tuna caught in the Pacific Ocean and the Japan Sea evidently reflect different water temperatures along the migratory route from their natal origin. Fish hatched in the Japan Sea experience water temperatures of

Some fish species exhibit a biochemical response to low winter temperatures. For example, after a period of cold acclimation, an increase in enzyme activity occurs. This can result in at least partial compensation in the rate of biochemical reactions of aerobic metabolism. Sea bass (Dicentrarchus labrax L. 1758) is a commercially important fish for the Mediterranean mariculture industry, which can grow satisfactorily in both freshwater (FW) and seawater (SW) conditions. The purpose of the present work was to evaluate the survival and growth of sea bass in FW earthen ponds. The experiment was initiated in September 2003 in order to avoid the water temperature highs during spring–summer and allow several weeks for acclimation before the winter temperature lows. Fish growth occurred for several months, but by the end of December 2003, ambient water temperature reached levels below 5°C and mass mortality occurred. The capacity of sea bass for thermal compensation was evaluated by monitoring the activity of cy...

The objective of this study was to fit a hydrothermal germination model to germination data for a seedlot of radiata pine (Pinus radiataD. Don). Seeds were incubated for 50 d at constant temperatures and water potentials (T = 12.5–32.5°C, Ψ = 0 to − 1.2 MPa). Most seeds completed germination within 50 d, but for low Ψ and/or non-optimal temperatures (T T>25°C) many seeds did not complete germination. In general, germination data conformed to the hydrothermal model. Departures from the model were encountered for slow-germinating seeds at suboptimal temperatures (T ≤ 20°C). To account for these departures, two alternative hydrothermal models were fitted with an additional term for an upwards shift in seed base water potential with increasing time to germination. The alternative models more correctly predicted germination time than the original model. Similarly, reduced percentage germination at supra-optimal temperatures (T>20°C) was explained by including a term in the hydrothermal model which shifted the base water potential of seeds upwards towards zero, which in turn reduced the predicted rate that hydrothermal time would be accumulated by seeds. The rate of this upwards shift in base water potential was dependent on time to complete germination and ambient water potential as well as supra-optimal temperature.

To determine if larval crabs alter their horizontal swimming behavior in response to biochemical cues in the water, fiddler crab (Uca pugnax) and blue crab (Callinectes sapidus) megalopae were video recorded in a laminar-flow flume while putative cues were introduced and allowed to establish a gradient in the flow field. Changes in horizontal orientation, distribution, and swimming velocity were observed for six different cue treatments. Overall results show that crab megalopae can detect biochemical cues in ambient water and that they adjust their horizontal swimming behavior in response to these cues. The dominant response was a change in swimming velocity in the presence of a cue. While this response may affect the dynamics of larval patches, it is not clear if swimming in the horizontal plane has a substantial effect on the spatial aggregation of the larvae in the field.

Aims: To evaluate the effectiveness of continuous separation channel centrifugation for concentrating Toxoplasma gondii and Cyclospora cayetanensis from drinking water and environmental waters. Methods and Results: Ready-to-seed vials with known quantities of T. gondii and C. cayetanensis oocysts were prepared by flow cytometry. Oocysts were seeded at densities ranging from 1 to 1000 oocysts l−1 into 10 to 100 l test volumes of finished drinking water, water with manipulated turbidity, and the source waters from nine drinking water utilities. Oocysts were recovered using continuous separation channel centrifugation and counted on membrane filters using epifluorescent microscopy. Recovery efficiencies of both parasites were ≥84% in 10 l volumes of drinking water. In source waters, recoveries ranged from 64% to 100%, with the lowest recoveries in the most turbid waters. Method precision was between 10% and 20% coefficient of variation. Conclusion: Toxoplasma gondii and C. cayetanensis are effectively concentrated from various water matrices by continuous separation channel centrifugation. Significance and Impact of the Study: Waterborne transmission of T. gondii and C. cayetanensis presents another challenge in producing clean drinking water and protecting public health. Detection of these parasites relies on effectively concentrating oocysts from ambient water, otherwise false negatives may result. Validation data specific to T. gondii and C. cayetanensis concentration methods are limited. Continuous separation channel centrifugation recovers oocysts with high efficiency and precision, the method attributes required to accurately assess the risk of waterborne transmission.