Warming Climate Shortens Ice Durations and Alters Freeze and Breakup Patterns in Swedish Water Bodies

Increasing air temperatures reduce the duration of ice cover on lakes and rivers, altering their water quality, ecology, biodiversity, and physical, economical and recreational function. Using a unique in-situ record of freeze and breakup dates, including records dating back to the beginning of the 18th century, we analyze changes in ice duration (i.e., first freeze to last breakup), freeze and breakup patterns across Sweden. Results indicate a significant trend in shorter ice duration (62 %), later freeze (36 %) and earlier breakup (58 %) dates from 1913–2014. In the latter 3 decades, the mean observed ice durations have decreased by about 11 days in northern (above 60N) and 28 days in southern Sweden, whereas the average freeze date occurred about 10 days later and breakup date about 17 days earlier in southern Sweden. The rate of change is roughly twice as large in southern Sweden as in its northern part. Sweden has experienced an increase in occurrence of years with an extremely short ice cover duration (i.e., less than 50 days), which occurred about eight times more often in southern Sweden than previously observed. Our analysis indicates that even a 1 °C increase in air temperatures in southern (northern) Sweden results in a mean decrease of ice duration of 22.5 (7.6) days. Given that warming is expected to continue across Sweden during the 21st century, we expect increasingly significant impacts on ice cover duration and hence, ecology, water quality, transportation, and recreational activities in the region.

ICE PHENOMENA IN THE WARTA RIVER IN POZNAŃ IN 1961– 2010

The article presents variability of ice phenomena in the Warta River in Poznań based on data recorded in the water gauge station in Poznań - Roch Bridge in 1961-2010. The work aims to characterize and analyze ice phenomena and related hazards. First dates (freeze date), last dates (thaw date) and duration of ice phenomena and particular forms of ice, i.e. frazil ice, border ice, ice cover, ice floes and ice jam, were determined. In case of ice cover, its thickness was also analyzed. In the analyzed period, ice phenomena in the Warta River in Poznań had the maximum duration of 118 days, the earliest date appearance was on November 7 and the last on March 28. The first ice form to appear was frazil ice, the last ice floes and the longest lasting - ice floes. In the entire analyzed period, 15 winter seasons featured ice cover. The longest duration of ice cover was 29 days and its maximum thickness was 8 cm.

Long-Term Changes in Ice Phenology of the Yellow River in the Past Decades

The authors quantitatively describe the changes in the characteristics of ice phenology including the flow rate and freeze/breakup dates of the Yellow River based on observations of the past 50 yr. In both the upper and lower reaches of the Yellow River, increasing temperature delays the freeze date and advances the breakup date, thus decreasing the number of freeze days and the expanse of river freeze. From 1968 to 2001, the freeze duration has shortened significantly by 38 days at Bayangaole and 25 days at Sanhuhe, respectively. From the early 1950s to the early 2000s, the changes in freeze and breakup dates have shortened the freeze duration in the lower reach of the Yellow River by 12 days. The flow rate has reduced from 500 to 260 m3 s−1, and the expanse of river freeze has also decreased significantly by about 310 km. In addition, in the lower reach of the river, the location of earliest ice breakup has shifted downstream significantly in the last 50 yr, although the location of earliest freeze exhibits little change.

287IN VITRO PRODUCTION OF HOLSTEIN EMBRYOS USING SEX SORTED SEMEN

Our objective was to explore the synergy between sexed semen and in vitro embryo production and assess benefits of these technologies on commercial farms. Ovaries were collected from high genetic merit Holstein cull cows via colpotomy or at the time of slaughter. Oocytes were aspirated from the ovaries, fertilized 20–24h later, and matured to the morula or blastocyst stage. Embryos were transferred into recipient Holstein cows and heifers on the same farms. Seven Wisconsin herds participated, and 365 embryos were produced from 104 donor cows. Only 272 of these embryos were transferred due to limited availability of recipients. Sexed semen from three Holstein sires was used. On average, 3.5±0.37 transferable embryos were produced per donor, including 1.4±0.18 grade 1 embryos and 1.5±0.20 grade 2 embryos. Individual farms averaged from 1.6 to 5.8 transferable embryos per donor. Laboratory data also revealed interesting results. On average 43.7±4.0 oocytes were collected per donor, and the number of usable oocytes (33.9±3.4), and percent embryos cleaved (52.1±1.9), were significant predicators of the number of blastocysts developed. We divided the usable oocytes and embryos cleaved per donor into quartiles. The fourth quartile for embryos cleaved was significantly greater (P<0.05) than the lower three quartiles, and the usable oocyte quartiles all significantly differed from each other. Semen freeze date was also a significant predicator of the number of blastocysts developed, suggesting significant variation in the quality of sorted semen per ejaculate. To preliminarily test the effect of sorting on the percentage of embryos developing to blastocyst stage, oocytes were recovered from ovaries collected at a slaughterhouse and fertilized using non-sorted semen or sex-sorted semen from the same sires. Oocytes (n=3312) fertilized using non-sorted semen tended (P=0.06) to produce more embryos developing to blastocyst stage than oocytes (n=1577) fertilized using sex-sorted semen (20.1±2.9% v. 12.2±2.3%, respectively). Preliminary pregnancy results show strong farm and sire effects. Overall conception rate was 36% for heifer recipients and 18milking cow recipients. These results suggest that low cost in vitro embryo production may have promise as an early system for utilizing sexed semen in dairy cattle breeding programs.

EFFECTS OF NITROGEN RATES AND FINAL FALL HARVEST TIMING ON SAGE (SALVIA OFFICINALIS)

Sage is a perennial, semi-evergreen herb and is a multiharvest crop. In a 4-year field study in Bixby, Okla., three N rates, including 60, 120, and 180 kg/h, and four fall harvest dates, including 40 and 20 days before the average first freeze date in Bixby, the average freeze date, and 20 days past the average freeze date were evaluated on sage (Salvia officinalis) production. The fall harvest dates were ≈20 Sept., 10 Oct., 1 Nov., or 20 Nov. each year. Plots were established with transplants in Spring 1990. On all plots, growing-season harvests were executed once in spring and once in summer, followed by the final harvest in the fall annually (1991 to 1994). Results indicated N effects on yield and the N × final fall harvest date interaction were not significant for any of the years. Yields were significantly reduced in the 40 and 20 days prefreeze date harvest treatment plots in 1992, 1993, and 1994 by a hard freeze of –7C on 2 Nov. 1991 with no prior killing frost. Plant stand loss was 61% and 8% in the 40 and 20 days prefreeze harvested plots, respectively. Injury, but not plant loss, in the 20 days prefreeze harvested plots contributed to the yield reduction. Yields in the two later final harvest treatment plots were not affected.