Field Studies on the Oxygen Requirements of Certain Fresh-Water Fishes

Secondarily marine vertebrates are thought to live independently of fresh water. Here, we demonstrate a paradigm shift for the widely distributed pelagic sea snake, Hydrophis ( Pelamis ) platurus , which dehydrates at sea and spends a significant part of its life in a dehydrated state corresponding to seasonal drought. Snakes that are captured following prolonged periods without rainfall have lower body water content, lower body condition and increased tendencies to drink fresh water than do snakes that are captured following seasonal periods of high rainfall. These animals do not drink seawater and must rehydrate by drinking from a freshwater lens that forms on the ocean surface during heavy precipitation. The new data based on field studies indicate unequivocally that this marine vertebrate dehydrates at sea where individuals may live in a dehydrated state for possibly six to seven months at a time. This information provides new insights for understanding water requirements of sea snakes, reasons for recent declines and extinctions of sea snakes and more accurate prediction for how changing patterns of precipitation might affect these and other secondarily marine vertebrates living in tropical oceans.

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Experimental and field studies on the viability of eggs, and the infectivity of third-stage larvae of the human hookworm Necator americanus recovered from the creek waters of the Niger Delta, Nigeria, and their epidemiological significance

Parasitology ◽

10.1017/s0031182000081695 ◽

1988 ◽

Vol 96 (1) ◽

pp. 111-117 ◽

Cited By ~ 5

Author(s):

J. K. Udonsi

Keyword(s):

Fresh Water ◽

Brackish Water ◽

Niger Delta ◽

Field Studies ◽

Host Population ◽

Water Contact ◽

Necator Americanus ◽

Brackish Waters ◽

Significant Difference ◽

Laboratory Cultures

SUMMARYIn a combined field and laboratory study, the eggs and 3rd-stage infective larvae of the human hookworm Necator americanus were recovered from the creek waters of the Niger Delta, Nigeria. They were tested for viability and infectivity. Eggs recovered from fresh water creeks showed a viability or hatching index of between 17·5 and 23·7%. Eggs recovered from brackish water showed a viability index of 18·8–21·4% in ‘normal’ cultures, and a maximum index of 6·3% when cultured in brackish water. The differences in the viability indices of these eggs were not significant (P > 0·05). Infective 3rd-stage larvae were recovered from both fresh creek water (205–258 L3/litre of water), and brackish water (45 L3/litre of water). Larvae hatched from brackish water eggs that were cultured in the brackish water were 20% infective by 3 days, but lost all infective potential by 7 days posthatching. Larvae from fresh water eggs, cultured in fresh water and ‘normal’ laboratory cultures reached 50% infectivity in 3–5 days, losing potential infectivity in 11–15 days posthatching. The infectivity patterns of larvae recovered directly from fresh and brackish waters did not differ significantly (P > 0·05) from the infectivity patterns of larvae recovered from laboratory cultures of eggs from all the experimental sources. Although larvae recovered directly from fresh and brackish waters survived in these respective media under laboratory conditions, there was a significant difference (P < 0·05) in their survival patterns. The survival and infectivity rates of field larvae were considerably reduced over time relative to control larvae. These results indicate that both contaminated fresh and brackish water creeks and their banks may form additional hookworm infection foci in areas where various water contact activities are carried out by the human host population.

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Fresh-Water Mollusks as Biomonitors for Ecotoxicity of Nanomaterials

Nanomaterials ◽

10.3390/nano11040944 ◽

2021 ◽

Vol 11 (4) ◽

pp. 944

Author(s):

Natalia Abramenko ◽

Petr Mashkin ◽

Sergey Volkov ◽

Vladimir Olshanskiy ◽

Leonid Kustov

Keyword(s):

Fresh Water ◽

Aquatic Environment ◽

Field Studies ◽

Physiological Parameters ◽

Toxic Effects ◽

Neural Systems ◽

Unio Tumidus

The use of different nanoparticles (NPs) is growing every year since discoveries of their unique properties. The wide use of nanomaterials has raised concerns about their safety and possible accumulation in the aquatic environment. Mussels are being considered as one of the most suitable organisms for bioaccumulation monitoring. Within our study, we focused on developing the method that can be applied in field studies of ecotoxicity and can be nondestructive and informative at early times of exposure, while at the same time being based on changes of physiological parameters of fresh water mussels. The changes in the cardiovascular and neural systems of mollusks (Anodonta anatina and Unio tumidus) were measured as biomarkers of toxic effects. Different monometallic and bimetallic NPs, silicon NPs with various ligands were applied as test substances. Changes in cardiovascular and neural functions were in good correlation with accumulation tests for all tested NPs.

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The Ecology of Large Mammals in Central Yellowstone - Sixteen Years of Integrated Field Studies

10.1016/s1936-7961(08)x0003-x ◽

2008 ◽

Keyword(s):

Field Studies ◽

Large Mammals

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Empty visual field studies: Some effects of corrective lenses, filters, and structure.

PsycEXTRA Dataset ◽

10.1037/e414122004-001 ◽

1964 ◽

Author(s):

Milton S. Katz ◽

Paul A. Cirincione ◽

William Metlay

Keyword(s):

Visual Field ◽

Field Studies

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Psychosocial work stress and impaired physiological sleep: A summary of a series of field studies

PsycEXTRA Dataset ◽

10.1037/e577572014-115 ◽

2013 ◽

Author(s):

Goran Kecklund ◽

Torbjorn Akerstedt

Keyword(s):

Work Stress ◽

Field Studies ◽

Psychosocial Work ◽

Physiological Sleep ◽

Psychosocial Work Stress

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Vocal signaling among male northern elephant seals: Behavioral field studies of honesty vs. associative learning

PsycEXTRA Dataset ◽

10.1037/e598052013-012 ◽

2012 ◽

Author(s):

Colleen Reichmuth ◽

Caroline Casey ◽

Isabelle Charrier ◽

Nicolas Mathevon ◽

Brandon Southall

Keyword(s):

Associative Learning ◽

Field Studies ◽

Elephant Seals ◽

Northern Elephant Seals ◽

Vocal Signaling

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Aplikasi metode tahanan jenis dalam studi geologi karst Gua Seropan di Gunung Kidul, Yogyakarta

JURNAL SUMBER DAYA AIR ◽

10.32679/jsda.v12i2.53 ◽

2017 ◽

Vol 12 (2) ◽

pp. 105-116

Author(s):

Pulung A. Pranantya ◽

Nurlia Sadikin

Keyword(s):

Fresh Water ◽

Ground Surface ◽

Water Source ◽

Raw Water ◽

Limited Information ◽

Resistivity Method ◽

Central Java ◽

Underground River ◽

Initial Exploration

In terms of geology, most areas in south of the Gunungkidul District in Central Java consist of the Wonosari formation limestone. The land is generally very dry and source of raw water is also difficult to reach. Findings on the existence of underground river in caves, however, indicate the potential amount of water within the area, especially in the eastern part of the Gunungkidul District. Although limited information available, some fishermen have discovered that Seropan cave contains fresh water source. This cave is situated at 65 m below the cliff. Initial exploration, which done using a multichannel resistivity method, confirmed the availability of freshwater in the cave and underground river. The isopach of cave depth is found in ranges of 80 200 m below the ground surface. The water of Seropan cave can be utilized by implementing pipeline or by drilling at the suggested point based on the interpretation results, i.e. 110o2223.6388 EL 8o42.874 SL. [DY1][PP2][DY1]Perbaiki grammarIn terms of geology, most areas in south of Gunungkidul District in Central Java consist of the Wonosari formation limestone. The land is generally very dry and source of raw water is also difficult to reach. Findings on the exixtence of underground river in caves, however, indicate potential amount of water within the area especially in eastern part of Gunungkidul District. Although limited information available, some fishermans has discovered that Seropan cave contain fresh water source. This cave is situated at 65 m below the cliff. Initial exploration, which done using multichannel resistivity method, confirmed the availability of freshwater in the cave and underground river. The iso pach of cave depth is found in ranges of 80 200 m below the ground surface. The water of Seropan cave can be utilized by implementing pipeline or by drilling at the suggested point based on the interpretation results i.e. 110o2223.6388 EL 8o42.874 SL.[PP2]Sudah diperbaiki

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Penggunaan Media Pembelajaran Berbasis Android untuk Meningkatkan Hasil Belajar Kognitif Siswa

Edugama: Jurnal Kependidikan dan Sosial Keagamaan ◽

10.32923/edugama.v5i2.972 ◽

2019 ◽

Vol 5 (2) ◽

pp. 104-111

Author(s):

Dian Puspita Eka Putri

Keyword(s):

High School Students ◽

Learning Outcomes ◽

Multimedia Learning ◽

Cognitive Learning ◽

Field Studies ◽

Research Subjects ◽

School Students ◽

Increase Student Achievement ◽

Post Test ◽

Test Result

This study aims to review the effectiveness of using android-based multimedia learning to improve achievement cognitive learning outcome of students. The research method is the analysis of field studies. The focus in this research is Multimedia which can influence cognitive learning outcomes of students. data obtained in this study from the literature and direct field observations. The research subjects were high school students in Yogyakarta. The result of analysis and discussion of research indicate that there is the influence of multimedia learning to increase student achievement, which is indicated by increasing post-test result than before not using multimedia learning. Posttest value is greater than pretest.

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