Strategies of a successful new invader in European fresh waters: fecundity and reproductive potential of the Ponto-Caspian amphipod Dikerogammarus villosus in the Austrian Danube, compared with the indigenous Gammarus fossarum and G. roeseli

1. Fecundity of a Dikerogammarus villosus population at Spitz was studied in the Austrian Danube during the 3‐year period 2002–2004. Ovigerous females were absent in October and November, and extremely scarce in December when the reproductive season started again slowly. From January to September pre‐copulatory pairs and egg‐carrying females were present. The reproductive cycle lasted for 9–10 months. 2. Various pigmentation phenotypes of D. villosus have been described in the literature. However, no significant differences were found between the reproductive variables studied here and several colour morphs. Mating was size‐assortative; mean body length of males was about 1.3 times greater than that of their potential mates, and the wet weight was approximately twice as heavy. 3. The relationship between the number of embryos per clutch and the wet weight of females was described by a 3‐parameter power equation. The population mean was 43 eggs with a range of five to 194 eggs. Eighty‐two specimens from 1359 D. villosus females had more than 100 eggs: the smallest of these females was 12 mm long (30 mg) wet weight, and the largest, which was 18 mm long (91 mg), had 194 eggs in embryonic development stage 4. 4. Numbers of embryos in developmental stages 2 (early egg stage) and 7 (newly hatched neonates) differed significantly with body wet weight of ovigerous females (P < 0.05). For an average female in the range 10–12 mm (20–30 mg) the number of juveniles in the brood pouch was 74% of the number of stage 2 eggs. This value can be interpreted as the survival rate of eggs. 5. The overall mean egg volume (EV, ±95% CL) of stage 2 eggs of D. villosus was 0.05 ± 0.001 mm³, and EV increased significantly at each stage of development. At stage 6, egg volume had increased by a factor of 2.6, and averaged 0.13 ± 0.001 mm³. In comparison, G. fossarum and G. roeseli had significantly larger eggs in all developmental stages. 6. Mean egg size of D. villosus (0.063 mm³) was maximal in January. For D. villosus (and G. roeseli) the minimum mean egg size occurred in September. In contrast to G. fossarum and G. roeseli, a second peak in egg size was not observed for D. villosus, and egg size fell more or less successively from January to September. 7. A simple index of fecundity was calculated from the number of stage 2 eggs divided by the female's wet weight. The highest values were observed in April and May, when females from the overwintering generation grew to their maximum body size. Thus the release of a large number of neonates corresponds with the availability of plentiful food and rising water temperatures for juvenile growth in the spring. The lowest value occurred in December. In June the small females of a summer generation appeared, with a naturally low fecundity. 8. The relationship between brood development time and water temperature was studied in the laboratory at a series of constant temperatures. At 16 °C, mean brood development time was 14 days for D. villosus, compared with about 3 weeks for the indigenous species. At 10 °C, mean brood development time was 24 days in D. villosus, compared with 40 days in G. fossarum and 44 days in G. roeseli. At 4 °C it was 1.8 and 3.5 times longer in G. fossarum and G. roeseli. 9. The number of offspring produced by a single clutch from a large female D. villosus is considerably higher than the total numbers produced by the indigenous freshwater gammarids, such as G. fossarum, G. roeseli and G. pulex, during their life‐spans of 1.5–2 years in seven to nine successive broods. Only one or two large ovigerous D. villosus would probably be enough to start a new population. A potentially high reproductive capacity, comparatively small eggs, optimal timing to release the maximum number of neonates per female in April/May, and a long reproductive cycle, together with rapid development of eggs, rapid growth to sexual maturation, short life span, tolerance to a wide range of environmental conditions, and exceptional predatory capabilities, all give the invasive Ponto‐Caspian gammarid an opportunity to become globally distributed in freshwater ecosystems of the temperate climate zone.     

Seasonal variation in fecundity,egg case viability,gestation, and neonate size for little skates, <Emphasis Type="Italic">Leucoraja erinacea</Emphasis>, in the Gulf of Maine

Landings of the little skate, Leucoraja erinacea, within the territorial waters of the United States are currently regulated by a federal fishery management plan (FMP). For a FMP to be effective, thorough knowledge of a species’ reproductive biology is essential. Currently, little information exists on annual fecundity, egg case viability, gestation length, and neonate total length, for the little skate in the Gulf of Maine. To study these reproductive parameters, mature skates and egg cases were housed in fiberglass tanks with an open seawater system that provided natural, seasonal fluctuations in water temperature. Egg case deposition was highest during summer months with a seasonal peak in June. Of the 324 egg cases laid by seven females (c. 46 eggs per year, per female), 74.1% were viable. Gestation lengths ranged from 22 to 54 weeks throughout the four seasons. Egg cases laid in the fall had the longest gestation times (44.9 weeks, ± 0.13 weeks) and those laid in the spring had the shortest gestation times (24.5 weeks, ± 0.21 weeks). Total lengths of neonates from spring oviposition were statistically the longest (10.74 ± 0.05 cm) when compared to neonates from other seasons; however, egg viability was statistically the lowest for spring when compared seasonally.     

Bionomics of the acarophagous ladybird beetle Stethorus tridens fed Tetranychus evansi

The bionomics of Stethorus tridens Gordon fed Tetranychus evansi Baker & Pritchard were studied in the laboratory. The number of prey consumed by S. tridens increased with increasing instar levels and the total mean number consumed during immature development was 184.1 ± 18.02 T. evansi nymphs per individual. For adult male and adult female, the daily consumption was 41.3 ± 0.80 and 67.8 ± 1.69 nymphs, respectively. Stethorus tridens successfully developed to adulthood between 20 and 30°C but failed at 10, 15 and 35°C. The lower thermal threshold for egg‐to‐adult development estimated via linear regression and the modified Logan model was 9.2 and 8.1°C, respectively. The optimum and maximum temperatures for egg‐to‐adult development were around 29–31 and 32.9°C, respectively. Egg to adult development time was 23.8 ± 0.24, 17.4 ± 0.22, 16.2 ± 0.22 and 12.1 ± 0.16 days at 20, 24, 27 and 30°C, respectively. At 27°C, the sex ratio, expressed as the proportion of females, was 0.54 and the mean preoviposition, oviposition and postoviposition periods were 10.3 ± 0.67, 31.2 ± 4.74 and 30.2 ± 5.24 days, respectively. The oviposition rate was 4.0 ± 0.16 eggs/female/day with a female mean longevity of 71.6 ± 6.19 days and an intrinsic rate of natural increase of 0.104. The potential of S. tridens as a candidate natural enemy of T. evansi is discussed.     

Effect of periphyton on growth performance of grey mullet, Mugil cephalus (Linn.), in inland saline groundwater ponds

The present study attempts to assess the potential of artificial substrates to enhance fish production in inland saline groundwater ponds through periphyton production. Grey mullet, Mugil cephalus, was cultured for 100 days in ponds with substrate (treatment ponds) and without substrate (control ponds). To enhance the surface area, bamboo poles were used as substrate. The periphyton population, pigment concentration and hydrobiological characteristics of pond water were monitored. The studies revealed little difference in most of the water quality parameters observed in the two treatments. However, turbidity (27.0 ± 0.1–35.0 ± 0.1 Nephalo Turbidity Unit (NTU)), chlorophyll ‘a’ (6.6 ± 0.6–7.6 ± 0.6 μg L^?1), plankton population (phytoplankton 8.4 × 10³–9.4 ×10³ numbers L^?1; zooplankton 4.0 × 10³–5.1 × 10³ numbers L^?1) and NH₄–N (2.0 ± 0.2–2.3 ± 0.1 mg L^?1) were high in the treatment with no additional substrate; however, in the treatment with substrate the total Kjeldahl nitrogen (9.8 ± 0.8–10.8 ± 0.7 mg L^?1) and o‐PO₄ (0.1 ± 0.01–0.1 mg L^?1) remained significantly (P < 0.05) higher. Highest periphyton biomass in terms of dry matter (DM) (0.8 ± 0.01–1.4 ±0.01 mg cm^?2), ash free DM (0.4 ± 0.0–0.6 ± 0.01 mg cm^?2), chlorophyll ‘a’ (3.1 ± 0.2–8.1 ± 0.8 μg cm^?2) and pheophytin ‘a’ (1.9 ± 0.4–3.9 ± 0.5 μg cm^?2) was observed at 50 cm depth in ponds provided with additional substrate. Fifteen plankton genera showing periphytic affinity colonized the bamboo substrates. Fish growth (mean fish weight 524.3 ± 8.7 g and SGR 2.5 ± 0.1) was significantly (P < 0.05) higher in ponds provided with additional substrate compared with control ponds (387.2 ± 6.0). Length–weight relationship (LWR) (W = cLⁿ) also showed that the exponential value (‘n’) of length was high in substrate‐supported ponds (n = 2.36) in comparison with controls (n = 1.09). These studies suggest that a periphyton‐supported aquaculture system can be used successfully for the culture of herbivorous brackishwater fish species like M. cephalus in inland saline groundwaters and thus could contribute to the development of sound and sustainable aquaculture technology.     

Daily growth patterns and age‐at‐recruitment of the anchoveta Engraulis ringens as indicated by a multi‐annual analysis of otolith microstructure across developmental stages

The anchoveta (Engraulis ringens ) plays a key role in the ecology of the Humboldt Current System and is of major economic importance; however, many aspects of its early life history are still poorly understood. In this study, an analysis of daily age and length patterns was carried out using the sagittal otoliths from wild larvae (0–0.2 cm standard length, L _S), pre‐recruits (3–6 cm total length, L _T), recruits (7–12 cm L _T) and young adults (12–15 cm L _T). Additionally, variability in growth and age at recruitment (A _R) were evaluated for recruits caught in northern Chile in 1973, 1982, 2009, 2010, 2012, 2013, 2014 and 2015. The age–length relationship showed four allometric patterns that were well described by Laird‐Gompertz models. The absolute growth rates at the inflexion point (G _AR) were 0.56, 0.75, 1.22 and 1.16 mm d^?1 for larvae, pre‐recruits, recruits and young adults, respectively. At the interannual scale, G _AR values were always >1 mm d^?1 (mean ± S.D . 1.37 ± 0.21 mm d^?1; range 1.12–1.64 mm d^?1), irrespective of the season of hatching (i.e. winter v. spring); additionally, in most cases, G _AR values were reached before the second month of life (mean ± S.D . 50.47 ± 9.73 days) at c. 4 cm L _T (mean ± S.D . 4.22 ± 0.29 cm). Mean A _R was < 150 days (112 ± 29 days; range 75–149 days); in contrast, estimates of A _R were higher and growth rates were lower in 1973, 1983 and 2000. These results demonstrate very fast growth and early A _R of anchoveta in northern Chile, suggesting most fish are removed by the fisheries at very early ages. An evaluation of the implications of these results on stock assessment and management of this species is highly recommended.     

Lifecycle of Rhipicephalus haemaphysaloides under laboratory conditions

Rhipicephalus haemaphysaloides Supino, 1897 (Ixodida: Ixodidae) is a three‐host hard tick widely distributed in Sri Lanka. The lifecycle of the R. haemaphysaloides population in Sri Lanka was studied under laboratory conditions using fully engorged females collected from dogs. Larvae, nymphs and adults were reared on New Zealand rabbits. Engorged females weighed a mean ± standard deviation (SD) of 470.1 ± 106.5 mg and laid a mean ± SD of 4067.4 ± 3136.2 eggs within 16.1 ± 3.7 days. The mean ± SD preoviposition period was 6.5 ± 1.1 days. The mean ± SD reproductive efficiency index was 8.5 ± 4.1, and was higher in heavier females (Pearson correlation, r = 0.8; P = 0.001). The incubation period of eggs was shorter at higher temperatures. The majority (86.9%) of larvae successfully moulted after a mean ± SD premoulting period of 7.9 ± 0.7 days following a parasitic period of 3.2 ± 0.5 days. Unfed larvae survived a mean ± SD of 103.4 ± 19.8 days. Nymphs completed the bloodmeal after 3.7 ± 0.9 days, weighed 5.7 ± 1.7 mg and demonstrated a premoulting period of 15.1 ± 1.9 days. Unfed nymphs survived a mean ± SD of 45.8 ± 3.8 days. Heavier nymphs moulted into females, whereas lighter nymphs moulted into males (two‐sample t‐test, P < 0.001). The bodyweight of adult females increased more than 100‐fold after feeding. The lifecycle of R. haemaphysaloides was successfully completed on rabbits within a mean of 91.3 days (range: 69–117 days) under laboratory conditions.     

Determination of polyphenolics in extracts of Potentilla species by high‐performance thin‐layer chromatography photodensitometry method

Introduction – Separation of polyphenolics in different plant materials using high‐performance thin‐layer chromatography (HPTLC) represents an effective method for their detection and quantification. Objective – To develop a simple, specific, precise, sensitive and accurate method for the simultaneous quantification of tiliroside (TRS), methyl brevifolincarboxylate (MBR) and ellagic acid (EA) in a plant extract using the HPTLC‐photodensitometry method. Methodology – Aerial parts of the selected Potentilla species, P. anserina, P. erecta, P. grandiflora and P. nepalensis var. ‘Miss Willmott’, were extracted with methanol. After solvent evaporation, the methanolic extracts were diluted with water and successively partitioned between chloroform and then diethyl ether. The diethyl ether extracts from each sample were used for quantification. The analyses were performed on HPTLC precoated silica gel 60F₂₅₄ plates with toluene–ethyl formate–formic acid (6 : 4 : 1 v/v/v) as the mobile phase (distance of 7.5 cm). Densitometric detections of TRS, MBR and EA were performed at 320, 287 and 280 nm, respectively. The amounts of these compounds were calculated using the regression equations of the calibration curves, which were linear within a range of 0.05–0.5 μg/spot (R² = 0.9957) for TRS, 0.05–0.525 μg/spot (R² = 0.9965) for MBR and 0.0525–0.5 μg/spot (R² = 0.9998) for EA. Results – The amounts of marker compounds measured by the method developed are expressed in mg/g of dry extracts. TRS ranged from 20.3 ± 0.3 mg/g for P. erecta herbs to 197.7 ± 2.9 mg/g for P. grandiflora herbs; MBR ranged from 5.0 ± 0.6 mg/g for P. erecta herbs to 68.5 ± 3.4 mg/g for P. nepalensis flowers; and EA ranged from 24.0 ± 0.6 mg/g for P. erecta herbs to 216.2 ± 3.2 mg/g for P. anserina leaves. Conclusion – The proposed method was found to be relatively simple, specific, precise, sensitive and accurate and may be used for the routine assay of simultaneous determination of TRS, MBR and EA in other extracts and phytomedicines containing Potentilla species. Copyright © 2009 John Wiley & Sons, Ltd.     

Determination of puerarin in biological samples and its application to a pharmacokinetic study by flow‐injection chemiluminescence

A simple and sensitive flow injection–chemiluminescence (FI–CL) method has been developed for the determination of puerarin, based on the fact that puerarin can greatly inhibit CL of the luminol–H₂O₂–haemoglobin system. The inhibition of CL intensity was linear to the logarithm of the concentration of puerarin in the range 0.08–10.0 μg/mL (r² = 0.9912). The limit of detection was 0.05 μg/mL (3σ) and the relative standard deviation (RSD) for 1.0 μg/mL (n = 11) of puerarin solution was 1.4%. Coupled with solid‐phase extraction (SPE) as the sample pretreatment, the determination of puerarin in biological samples and a preliminary pharmocokinetic study of puerarin in rats were performed. The recoveries for plasma and urine at three different concentrations were 89.2–110.0% and 91.4–104.8%, respectively. The pharmacokinetics of puerarin in plasma of rat coincides with the two‐compartment open model. The T_1/2α, T_1/2β, CL/F, V_Z/F, AUC_{(0 – t)}, MRT_{(0 – ∞)}, T_max and C_max were 0.77 ± 0.21 h, 7.55 ± 2.64 h, 2.43 ± 1.02 L/kg/h, 11.40 ± 3.45 L/kg, 56.67 ± 10.65 mg/h/L, 5.04 ± 2.78 h, 1.00 ± 0.35 h and 19.70 ± 4.67 μg/mL, respectively. Copyright © 2011 John Wiley & Sons, Ltd.     

Regulate or tolerate: Thermal strategy of a coral reef flat resident,the epaulette shark,Hemiscyllium ocellatum

Highly variable thermal environments, such as coral reef flats, are challenging for marine ectotherms and are thought to invoke the use of behavioural strategies to avoid extreme temperatures and seek out thermal environments close to their preferred temperatures. Common to coral reef flats, the epaulette shark (Hemiscyllium ocellatum) possesses physiological adaptations to hypoxic and hypercapnic conditions, such as those experienced on reef flats, but little is known regarding the thermal strategies used by these sharks. We investigated whether H. ocellatum uses behavioural thermoregulation (i.e., movement to occupy thermally favourable microhabitats) or tolerates the broad range of temperatures experienced on the reef flat. Using an automated shuttlebox system, we determined the preferred temperature of H. ocellatum under controlled laboratory conditions and then compared this preferred temperature to 6 months of in situ environmental and body temperatures of individual H. ocellatum across the Heron Island reef flat. The preferred temperature of H. ocellatum under controlled conditions was 20.7 ± 1.5°C, but the body temperatures of individual H. ocellatum on the Heron Island reef flat mirrored environmental temperatures regardless of season or month. Despite substantial temporal variation in temperature on the Heron Island reef flat (15–34°C during 2017), there was a lack of spatial variation in temperature across the reef flat between sites or microhabitats. This limited spatial variation in temperature creates a low-quality thermal habitat limiting the ability of H. ocellatum to behaviourally thermoregulate. Behavioural thermoregulation is assumed in many shark species, but it appears that H. ocellatum may utilize other physiological strategies to cope with extreme temperature fluctuations on coral reef flats. While H. ocellatum appears to be able to tolerate acute exposure to temperatures well outside of their preferred temperature, it is unclear how this, and other, species will cope as temperatures continue to rise and approach their critical thermal limits. Understanding how species will respond to continued warming and the strategies they may use will be key to predicting future populations and assemblages.     

Behavioural salinity preferences of juvenile green sturgeon Acipenser medirostris acclimated to fresh water and full‐strength salt water

To quantify the salinity preference of juvenile green sturgeon Acipenser medirostris, two groups of A. medirostris [140 days post hatch (dph); total length (L_T) 38·0–52·5 cm] were acclimated to either near fresh water (mean ± s.e . salinity = 3·2 ± 0·6) or full‐strength salt water (34·1 ± 1·2) over 8 weeks. Following acclimation, the two groups were divided into experimental and control groups, where experimental A. medirostris from both freshwater and saltwater acclimations were individually introduced (200–220 dph) into a rectangular salinity‐preference flume (maximum salinity gradient: 5–33). Control A. medirostris were presented with only their acclimation water (fresh water or salt water) on both sides of the flume. It was demonstrated that A. medirostris acclimated to both salt water and fresh water spent a significantly greater amount of time on the side of the testing area with the highest salinity concentration (P < 0·05 and P < 0·001, respectively) while control A. medirostris spent an equal amount of time on each side of the flume. These findings indicate that juvenile A. medirostris are not only capable of detecting salt water within the first year of their lives but perhaps are actively seeking out saline environments as they move through a watershed. Establishing A. medirostris salinity preferences provides a better understanding of the early life history of this threatened species, shedding light on possible outmigration timing.     

Extreme seasonality of litter breakdown in an arctic spring‐fed stream is driven by shredder phenology,not temperature

1. Using degree‐days to calculate ‘temperature‐corrected’ breakdown rates is a useful approach for comparing litter breakdown across sites with different thermal regimes. We used an alternative approach to investigate the importance of temperature by quantifying seasonal patterns in litter breakdown in an arctic spring‐fed stream (Ivishak Spring, North Slope, Alaska) that experiences extreme seasonality in light availability and energy inputs while fluctuations in water temperature are relatively small. 2. We incubated mesh bags of senesced Salix alaxensis litter in Ivishak Spring for successive c. 30‐day periods for 2 years. During our study, water temperature was very stable [5.7 ± 0.03 °C (daily mean ± 1 SE), range 3.7–7.8 °C]. Discharge was only slightly more variable (mean 112 ± 1 L s^?1, range 66–206 L s^?1), with lowest values occurring in late winter. Dissolved nutrient concentrations were low (52–133 μg L^?1, <1–3 μg L^?1, <1–6 μg L^?1 soluble reactive phosphorus) and also showed evidence of seasonality (i.e. highest values in winter). 3. Litter breakdown rates were sharply seasonal, ranging from <0.01 day^?1 in mid‐summer to >0.05 day^?1 in mid‐winter. Invertebrate assemblage structure in litter bags showed pronounced seasonal cyclicity; total invertebrate biomass peaked in summer. Biomass of two dominant shredders (the nemourid stonefly Zapada haysi and the limnephilid caddisfly Ecclisomyia conspersa) showed the opposite trend, however, with mid‐winter peaks in both population biomass and cohort growth rates that closely matched those we observed in litter mass loss. 4. Water temperature appeared to have negligible influence on litter breakdown rates in our study. Seasonal shifts in nutrient uptake may have increased rates of microbial activity in winter. The processing of litter inputs in Ivishak Spring, however, appeared to be most tightly coupled to shredder phenology. Our results demonstrate that extreme seasonality in the processing of allochthonous detritus can occur even in the absence of substantial temperature variation, driven by the activity of shredder taxa that have evolved to take advantage of pulsed organic matter inputs.     

Breeding ecology of Red‐faced Cormorants in the Pribilof Islands,Alaska

ABSTRACT Red‐faced Cormorants (Phalacrocorax urile) are North Pacific endemics recognized as a vulnerable species, but little is known about their breeding ecology. We studied Red‐faced Cormorants on St. Paul Island, Alaska, from 1975 to 2009, with more detailed data collected in 2004 and 2005. Mean clutch sizes in 2004 (3.2 ± 0.8 [SD] eggs) and 2005 (3.1 ± 0.8 eggs) were similar to the long‐term average (2.9 ± 0.3 eggs from 1976 to 2009). The mean laying interval in 2004 and 2005 was 2.15 ± 0.80 d (N= 407), and the mean egg period (number of days between laying of an egg and hatching) was 31.1 ± 1.4 d (N= 158). Approximately 64 ± 17% of eggs hatched during the period from 1975 to 2009. The mean number of chicks per nest in 2004 and 2005 was 2.8 ± 0.8 (N= 232), and the mean number of fledglings per initiated nest in all years was 1.22 ± 0.52. Chicks fledged 46 to 66 d posthatching. In 2004 and 2005, the primary causes of egg loss were predation by Arctic foxes (Vulpes lagopus) and destruction of eggs and abandonment of nests due to storms. Starvation was the primary cause of nestling mortality in both years. Because chicks are dependent on parents to provide food for over 45 d, consistent near‐shore foraging opportunities must be available. From 1975 to 2009, Red‐faced Cormorants experienced only 1 yr of complete reproductive failure (1984). The consistent reproductive success of Red‐faced Cormorants suggests that conditions may be relatively stable for this species on St. Paul Island, or that the variability in their breeding ecology (e.g., phenology, clutch sizes, and incubation strategies) provides the flexibility needed to successfully fledge some chicks nearly every year.     

Assessment of egg quality and realised fecundity of whiting Merlangius merlangus L. in captivity

Potential predictors of egg quality were assessed in whiting Merlangius merlangus L. permitted to spawn in a tank from which eggs were collected. These included fertilisation rate, the proportion of viable buoyant eggs, egg diameter, and egg wet and dry weights; all were influenced by temporal effects and were negatively correlated with days from start of spawning. The spawning period was protracted, from February to June. Mean daily egg production per female was 2.74 ± 2.43 g and 2338 ± 2075 eggs, equivalent to 14.6 ± 13.1 g kg^?1 day^?1 female^?1. Egg diameter was 1.21 ± 0.04 mm, egg wet weight 1.20 ± 0.21 mg, dry weight 0.10 ± 0.02 mg, and mean fertilisation rate and hatching rates were 76.8 and 73.3%, respectively. The incubation period ranged from 72 to 80 degree days and was dependent on temperature (x) and described by the equation y = 25.92 e^?0.1219x. Realised fecundity was also assessed to determine if this gave a more accurate measure of reproductive potential, and this was compared with potential fecundity estimated from predictive regressions on fish length from fisheries data. Realised egg production of 20 females of 185 g mean weight and 256 mm fork length was 4 444 360 (95% CL 4 093 961–4 743 018), similar to predicted seasonal egg production based on gravimetric fecundity measurements of wild caught fish.     

Evaluation of swimming performance for fish passage of longnose dace Rhinichthys cataractae using an experimental flume

The swimming performance of longnose dace Rhinichthys cataractae, the most widely distributed minnow (Cyprinidae) in North America, was assessed in relation to potential passage barriers. The study estimated passage success, maximum ascent distances and maximum sprint speed in an open‐channel flume over a range of water velocities and temperatures (10·7, 15·3 and 19·3° C). Rhinichthys cataractae had high passage success (95%) in a 9·2 m flume section at mean test velocities of 39 and 64 cm s^–1, but success rate dropped to 66% at 78 cm s^–1. Only 20% of fish were able to ascend a 2·7 m section with a mean velocity of 122 cm s^–1. Rhinichthys cataractae actively selected low‐velocity pathways located along the bottom and corners of the flume at all test velocities and adopted position‐holding behaviour at higher water velocities. Mean volitional sprint speed was 174 cm s^–1 when fish volitionally sprinted in areas of high water velocities. Swimming performance generally increased with water temperature and fish length. Based on these results, fishways with mean velocities <64 cm s^–1 should allow passage of most R. cataractae. Water velocities >100 cm s^–1 within structures should be limited to short distance (<1 m) and structures with velocities ≥158 cm s^–1 would probably represent movement barriers. Study results highlighted the advantages of evaluating a multitude of swimming performance metrics in an open‐channel flume, which can simulate the hydraulic features of fishways and allow for behavioural observations that can facilitate the design of effective passage structures.     

Adherence to vitamin supplementation following adolescent bariatric surgery

Objective: Adolescents with extreme obesity, who have undergone bariatric surgery, must adhere to many lifestyle and nutritional recommendations, including multivitamin therapy. Little is known about multivitamin adherence following adolescent bariatric surgery. Design and Methods: The present study aims to document self‐reported and electronically‐monitored adherence to multivitamins, determine convergence between self‐report and electronic monitoring adherence for multivitamins, and identify barriers to multivitamin adherence for adolescents who have undergone bariatric surgery. Results: The study used a prospective, longitudinal observational design to assess subjective (self‐reported) and objective (electronic monitors) multivitamin adherence in a cohort of 41 adolescents (Mean age = 17.1 ± 1.5; range = 13‐19) who have undergone bariatric surgery at Cincinnati Children's Hospital Medical Center. Mean adherence as derived from electronic monitoring for the entire 6‐month study period was 29.8% ± 23.9. Self‐reported adherence was significantly higher than electronically monitored adherence across both the 1 and 6‐month assessment points (z = 4.5, P < 0.000 and z = 4.0, P < 0.0001, respectively). Forgetting and difficulty swallowing multivitamins were the two primary barriers identified. While there are no established data regarding best practice for multivitamins following bariatric surgery, high rates of nonadherence to multivitamin therapy were observed in adolescents who had undergone bariatric surgery with forgetting and difficulty swallowing pills as reported barriers to adherence. Conclusion: These high rates of nonadherence to multivitamin therapy should be considered when devising treatment and family education pathways for adolescents considering weight loss surgery.     

Life history of a dipteran predator (Scathophagidae: Acanthocnema) of insect egg masses in a northern California stream

1. Little is known about the predators of insect eggs in fresh waters. This study describes aspects of the life history of a scathophagid fly (Acanthocnema sp.), whose larvae are predators of aquatic insect eggs. 2. Because the Acanthocnema predator oviposits its eggs on the surface of aquatic insect egg masses, all insect egg masses were collected regularly within a 200‐m reach of Redwood Creek (California, U.S.A.) between September 2003 and June 2007. Acanthocnema predators were found predominantly within egg masses of the caddifly Neophylax rickeri (Trichoptera: Uenoidae). 3. There was a mean of 0.25 Acanthocnema individuals per N. rickeri egg mass (n = 2367 egg masses). In general, N. rickeri egg masses were more commonly found clustered in aggregations (93.7%) than singly (6.3%), and Acanthonema were found more often within the aggregations of N. rickeri (98.7%) compared to singly laid egg masses (1.3%). 4. The duration of the Acanthocnema predator life stages was: egg 2.9 ± 0.8 (mean ± SD) days, larva 15.6 ± 10.2 days, pupa 80.3 ± 24.9 days and adult 7.2 ± 4.8 days. The short duration of the Acanthocnema egg stage (1–7 days) compared to that of its prey N. rickeri (2–4 weeks) raises the probability that the undeveloped eggs of N. rickeri would be available to the young predators upon hatching. Egg consumption of N. rickeri eggs by Acanthocnema averaged 262.6 eggs per larval period. 5. Acanthocnema had a bivoltine life cycle in which the first generation fed exclusively on N. rickeri egg masses in the winter and the second generation fed on the egg masses of several species, including other Trichoptera (Brachycentridae) and Diptera (Ceratopogonidae, Chironomidae) in the spring. These findings suggest differing feeding strategies by the first and second generations of Acanthocnema in response to the seasonal availability of prey species. This type of autecological information is important for understanding mechanisms of community interactions.     

Validation of daily microincrement deposition in otoliths of juvenile and adult Peruvian anchovy Engraulis ringens

Wild adult specimens of the Peruvian anchovy Engraulis ringens were captured and reared to validate the daily periodicity of otolith microincrement formation. The postcapture stress generated spontaneous spawning, making it possible to conduct a rearing trial on larvae first in an artificial nutrient‐enriched system (ANES) for 52 days followed by an artificial feeding regime in a culture tank until day 115 post‐hatch. Microincrements of the sagittal otoliths of sacrificed juveniles [mean ± s.d. total length (L_T) = 5·13 ± 0·37 cm, range 5–6 cm; c.v. = 7·5%] showed very distinct light and dark zones. The slope of the relationship between the total number of increments after the hatch check and days elapsed after hatching was not significantly different from 1. The transfer from ANES to the artificial feeding regime induced a mark in the sagittal otoliths. The number of microincrements after this induced mark coincided with the number of days elapsed after the transfer date. In parallel experiments, adult E. ringens (mean ± s.d. L_T = 14·92 ± 0·55 cm, range 13–16 cm) were exposed to one of two fluorescent marking immersion treatments with either alizarin red S (ARS; 25 mg l^?1 per 6 h) or oxytetracycline hydrochloride (OTC; 200 mg l^?1 per 10 h). The microincrements between fluorescent bands were distinct, ranging from 0·89 to 2·75 µm (mean ± s.d. =1·43 ± 0·28 µm; c.v. = 32%) and from 0·71 to 2·89 µm (1·53 ± 0·27 µm; c.v. = 35%) for ARS and OTC, respectively. The relationship between the number of microincrements between marks and the number of elapsed days for ARS and OCT treatments indicated that there was a significant correspondence between the number of increases observed and the number of days. Hence, daily microincrements of otoliths of E. ringens are likely to be formed in juveniles and adults under natural conditions.     

The morphometrics and colouration of the European pond turtle Emys orbicularis in Lubuskie province (West Poland)

The European pond turtle Emys orbicularis, is an endangered species in Poland. The region of the Ilanka River, in the western part of the country (Lubuskie province), is the most densely inhabited area by the species. Several populous sites are dispersed over the whole area of the province. Over the past 10 years, 279 turtles were captured at 11 sites. In 218 individuals, those with a straight carapace length (SCL) between 2.10–12.10 cm, sex was not determined; the remaining 61 with SCL 13.33–19.85 cm were sexed. Females had bigger bodies and were heavier than males. The SCL of females was 17.10 ± 1.7 cm (average ± SD, n = 33), their body mass (BM) was 790.6 ± 228.7 g (n = 27), and in the case of males SCL was 15.44 ± 1.5 cm and BM was 554.2 ± 138.8 g (n = 28). SCL of the smallest egg laying female was 15.30 cm, and SCL of the smallest mating male was 13.33 cm. The colouration of the turtles which undergoes change with age can be varied.