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Intermittent Stream (intermittent + stream)

Distribution by Scientific Domains
Life Sciences80%

Selected Abstracts

Responses of Aquatic Macrophytes to Disturbance by Flash Floods in a Brazilian Semiarid Intermittent Stream,

BIOTROPICA, Issue 4 2001
Leonardo Maltchik
ABSTRACT Resistance and resilience of Najas marina to disturbance by flash floods were studied in a permanent fluvial pool of a Brazilian semiarid intermittent stream. A total of 21 macrophyte samples was collected in the high-rainfall season during two annual cycles (1996,1997). Decreases in macrophyte biomass were positively correlated with flood magnitude (Pearson, P = 0.047), varying from 25 to 53 percent when discharges were lower than or equal to 0.5 m3/ sec and between 70 and 100 percent when discharges were higher than 1.0 m- 3/sec. Macrophyte resilience was greater after floods of low magnitude. After floods of 0.5 m- 3/sec, three weeks were necessary to re-establish 88 percent of biomass lost, and after a flood of 1.4 m-Vsec, six months were needed to initiate A, marina regrowth. This population of N. marina in Avelós stream has higher stability in response to small disturbances, but as expected, its resistance and resilience decreases with larger disturbances. In general, the high resistance and resilience of N. marina m response to small disturbances have been observed in intermittent tropical streams. The absence of large floods during the study period and the low variability of water temperature in this tropical region may have influenced these results. RESUMES A influencia de cheias rápidas na resistência e na resistência de Najas marina foram estudadas em uma poça fluvial permanente de um riacho efêmero do Semi-árido Brasileiro. Vinte e uma coletas de macrófitas aquáticas foram realizadas durante o período de chuvas de dois ciclos anuais (1996 e 1997). A variaçäo da biomassa de macrófitas aquáticas estava diretamente correlacionada com a magnitude da cheia (Pearson, P=0.047), variando entre 25 e 53 por cento quando as vazöes eram inferiores ou iguais à 0.5 m3 -Vsec e entre 70 e 100 por cento quando as vazöes eram superiores à 1.0 m3/sec. A resiliência de macrófitas era maior após às cheias de baixa magnitude. Após a cheia de 0.5 m3 -Vsec, foram necessários seis meses para restabelecer 88 por cento da biomassa perdida, e após a cheia de 1.4 m3/ sec, foram necessáries seis meses para iniciar a resiliência de Najas marina. Esta populaçäo de N. marina do riacho Avelós apresentou maior estabilidade frente ás perturbaçöes hidrológicas de baixa magnitude, mas a resistêncía e a resiliéncia diminuíam à medida que a magnitude da perturbaçao aumentava. A alta resístência e resiliência de N marina frente às perturbaçöes hidrológicas de baixa magnitude, geralmente tem sido observadas em riachos intermi-tentes tropicais. A ausência de grandes cheias durante o periodo estudado e a pequena amplitude térmica da água superficial desta regiäo tropical podem ter favorecido estes resultados. [source]

Factors related to lower urinary tract symptoms among a sample of employed women in Taipei,,§

NEUROUROLOGY AND URODYNAMICS, Issue 1 2008
Yuan-Mei Liao
Abstract Aim To identify factors associated with lower urinary tract symptoms (LUTS) among female elementary school teachers in Taipei. Methods This study is a cross-sectional, descriptive study. A total of 520 surveys were distributed to 26 elementary schools in Taipei. Logistic regression was used to identify possible factors related to individual LUTS. Results Study results were based on the information provided by 445 participants. Of the 445 teachers, 293 (65.8%) experienced at least one type of LUTS. Factors associated with urinary incontinence were body mass index (BMI), vaginal delivery, obstetric and/or gynecological surgery, bladder habits, and job control. Increased daytime urinary frequency was associated with chronic cough and chronic constipation. Bladder habits, straining to lift heavy objects at work and chronic constipation were associated with urgency. Nocturia was associated with age and caffeine consumption while intermittent stream was associated with the presence of a family history of LUTS and chronic constipation. Bladder habits and regular exercise were associated with weak urinary stream. Incomplete emptying was more likely to occur in teachers with chronic constipation and in those who did not exercise regularly. Conclusion All the LUTS under logistic regression analyses were associated with 1,3 modifiable factors. Identification of these modifiable contributing factors may be useful to health care providers. Education of women may include the importance of maintaining normal body weight, good bladder/bowel habits, and regular exercise, treating chronic cough, decreasing daily caffeine consumption, and implementing feasible environmental modifications in employment settings. Neurourol. Urodynam. © 2007 Wiley-Liss, Inc. [source]

Responses of Aquatic Macrophytes to Disturbance by Flash Floods in a Brazilian Semiarid Intermittent Stream,

BIOTROPICA, Issue 4 2001
Leonardo Maltchik
ABSTRACT Resistance and resilience of Najas marina to disturbance by flash floods were studied in a permanent fluvial pool of a Brazilian semiarid intermittent stream. A total of 21 macrophyte samples was collected in the high-rainfall season during two annual cycles (1996,1997). Decreases in macrophyte biomass were positively correlated with flood magnitude (Pearson, P = 0.047), varying from 25 to 53 percent when discharges were lower than or equal to 0.5 m3/ sec and between 70 and 100 percent when discharges were higher than 1.0 m- 3/sec. Macrophyte resilience was greater after floods of low magnitude. After floods of 0.5 m- 3/sec, three weeks were necessary to re-establish 88 percent of biomass lost, and after a flood of 1.4 m-Vsec, six months were needed to initiate A, marina regrowth. This population of N. marina in Avelós stream has higher stability in response to small disturbances, but as expected, its resistance and resilience decreases with larger disturbances. In general, the high resistance and resilience of N. marina m response to small disturbances have been observed in intermittent tropical streams. The absence of large floods during the study period and the low variability of water temperature in this tropical region may have influenced these results. RESUMES A influencia de cheias rápidas na resistência e na resistência de Najas marina foram estudadas em uma poça fluvial permanente de um riacho efêmero do Semi-árido Brasileiro. Vinte e uma coletas de macrófitas aquáticas foram realizadas durante o período de chuvas de dois ciclos anuais (1996 e 1997). A variaçäo da biomassa de macrófitas aquáticas estava diretamente correlacionada com a magnitude da cheia (Pearson, P=0.047), variando entre 25 e 53 por cento quando as vazöes eram inferiores ou iguais à 0.5 m3 -Vsec e entre 70 e 100 por cento quando as vazöes eram superiores à 1.0 m3/sec. A resiliência de macrófitas era maior após às cheias de baixa magnitude. Após a cheia de 0.5 m3 -Vsec, foram necessários seis meses para restabelecer 88 por cento da biomassa perdida, e após a cheia de 1.4 m3/ sec, foram necessáries seis meses para iniciar a resiliência de Najas marina. Esta populaçäo de N. marina do riacho Avelós apresentou maior estabilidade frente ás perturbaçöes hidrológicas de baixa magnitude, mas a resistêncía e a resiliéncia diminuíam à medida que a magnitude da perturbaçao aumentava. A alta resístência e resiliência de N marina frente às perturbaçöes hidrológicas de baixa magnitude, geralmente tem sido observadas em riachos intermi-tentes tropicais. A ausência de grandes cheias durante o periodo estudado e a pequena amplitude térmica da água superficial desta regiäo tropical podem ter favorecido estes resultados. [source]

Effect of fire on benthic algal assemblage structure and recolonization in intermittent streams

AUSTRAL ECOLOGY, Issue 6 2006
AMANDA L. COWELL
Abstract: Dry biofilm on rocks and other substrata forms an important drought refuge for benthic algae in intermittent streams following the cessation of flow. This dry biofilm is potentially susceptible to disturbance from bushfires, including direct burning and/or scorching and damage from radiant heat, particularly when streams are dry. Therefore, damage to dry biofilms by fire has the potential to influence algal recolonization and assemblage structure in intermittent streams following commencement of flow. The influence of fire on benthic algal assemblages and recolonization was examined in intermittent streams of the Grampians National Park, Victoria, Australia, using a field survey and manipulative field experiment. The field survey compared assemblages in two intermittent streams within a recently burnt area (within 5 months of the fire) with two intermittent streams within an unburnt area. The two burnt streams were still flowing during the fire so most biofilms were not likely to be directly exposed to flames. Considerable site-to-site and stream-to-stream variation was detected during the field survey, which may have obscured potential differences attributable to indirect effects of the fire. The manipulative field experiment occurred in two intermittent streams and consisted of five treatments chosen to replicate various characteristics of bushfires that may influence dry biofilms: dry biofilm exposed directly to fire; dry biofilm exposed to radiant heat; dry biofilm exposed to ash; and two procedural controls. After exposure to the different treatments, rocks were replaced in the streams and algae were sampled 7 days after flow commenced. Differences occurred across treatments, but treatment differences were inconsistent across the two streams. For example, direct exposure to fire reduced the abundance of recolonizing algae and altered assemblage structure in both streams, while radiant heat had an effect on assemblage structure in one stream only. The manipulative field experiment is likely to have represented the intensity of a small bushfire only. Nonetheless, significant differences across treatments were detected, so these experimental results suggest that fire can damage dry biofilms, and hence, influence algal recolonization and assemblage structure in intermittent streams. [source]