Population dynamics and reproduction ofHolothuria arenicola(Holothuroidea: Echinodermata) in coastal waters of Pakistan, North Arabian Sea

2015 ◽  
Vol 95 (6) ◽  
pp. 1245-1254 ◽  
Author(s):  
Saima Siddique ◽  
Zarrien Ayub
Keyword(s):  
Coastal Waters ◽  
Body Shape ◽  
Gonad Index ◽  
Significant Negative Correlation ◽  
Temporal Variations ◽  
Early Summer ◽  
Rocky Shores ◽  
Distribution Analysis ◽  
Autumn And Winter ◽  
Holothuria Arenicola

In Pakistan, although the sea cucumber fishery has not yet been developed,Holothuria arenicolais abundant on its coast. Nineteen months of sampling was carried out to study the population structure, allometric relationships and reproductive status ofH. arenicolastocks in Manora and Buleji rocky shores. All measured biometric characters showed significant temporal variations and width/length, weight/length, gutted weight/length and gutted weight/weight relationships followed negative allometry, indicating a change in body shape as the animal grows. Length-frequency distribution analysis was bimodal in both summer and autumn consisting of small-sized and medium-sized individuals while in winter and spring three modes were found at Manora. At Buleji, the population was unimodal in all seasons consisting of small-sized individuals. Sex inH. arenicolacannot be determined externally but can be identified on examination of gonad colour which is orange-like in females and creamy yellow in males. The sex was further confirmed on histological examination and maturation was divided into five stages, i.e. undetermined, early developing, late developing, mature and partially spawned. The sex ratio inH. arenicolawas approximately 1:1 and increase in gonad index was observed during spring and early summer, followed by a decrease in GI in autumn and winter, which showed the spawning followed by resting phase. The GI showed a significant negative correlation with salinity and non-significant correlation with temperature. There is a need to undertake more biological/ecological studies onH. arenicolain order to take effective measures for its management.

Phytoplankton species successions and their hydrological environment at a coastal station off Sydney

1986 ◽  
Vol 37 (3) ◽  
pp. 361 ◽  
Author(s):  
GM Hallegraeff ◽  
DD Reid
Keyword(s):  
Coastal Waters ◽  
Early Summer ◽  
Phytoplankton Species ◽  
Species Occurrence ◽  
Short Term ◽  
Coastal Station ◽  
Tropical Water ◽  
Diatom Blooms ◽  
Autumn And Winter ◽  
Water Species

Phytoplankton species occurrence was studied during 1978-1981 at a coastal station off Sydney and succession patterns were sought using polythetic agglomerative classification analysis. Three major phytoplankton categories were distinguished: (1) a large group of species (including most nanoplankton), which were present throughout the year; (2) a group of diatom species, which bloomed following episodic nutrient enrichments in spring, early summer, autumn and winter; (3) a group of warm-water species (e.g. Trichodesmium), which were associated with admixture of tropical water masses. Gross features of the phytoplankton cycle in these waters are related to the erratic flow pattern of the East Australian Current. However, clear short-term (4-14 weeks) species successions were evident within the spring and summer diatom blooms. These began with small diatoms (Asterionella, Leptocylindrus, Skeletonema, Thalassiosira) followed first by large diatoms (Detonula, Rhizosolenia, Stephanopyxis) and then by large dinoflagellates (Ceratium, Protoperidinium). This sequence is identical to that observed in coastal waters of other parts of the world. A phytoplankton checklist (280 species) for Sydney coastal waters is included as an appendix.

scholarly journals Spatial and seasonal variability of PM<sub>2.5</sub> acidity at two Chinese megacities: insights into the formation of secondary inorganic aerosols

2012 ◽  
Vol 12 (3) ◽  
pp. 1377-1395 ◽  
Author(s):  
K. He ◽  
Q. Zhao ◽  
Y. Ma ◽  
F. Duan ◽  
F. Yang ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Temporal Variations ◽  
Early Summer ◽  
Heterogeneous Reactions ◽  
Rural Site ◽  
Urban Site ◽  
Simultaneous Increase ◽  
Northwestern Pacific ◽  
Inorganic Aerosols ◽  
Aerosol Acidity

Abstract. Aerosol acidity is one of the most important parameters influencing atmospheric chemistry and physics. Based on continuous field observations from January 2005 to May 2006 and thermodynamic modeling, we investigated the spatial and seasonal variations in PM2.5 acidity in two megacities in China, Beijing and Chongqing. Spatially, PM2.5 was generally more acidic in Chongqing than in Beijing, but a reverse spatial pattern was found within the two cities, with more acidic PM2.5 at the urban site in Beijing whereas the rural site in Chongqing. Ionic compositions of PM2.5 revealed that it was the higher concentrations of NO3− at the urban site in Beijing and the lower concentrations of Ca2+ within the rural site in Chongqing that made their PM2.5 more acidic. Temporally, PM2.5 was more acidic in summer and fall than in winter, while in the spring of 2006, the acidity of PM2.5 was higher in Beijing but lower in Chongqing than that in 2005. These were attributed to the more efficient formation of nitrate relative to sulfate as a result of the influence of Asian desert dust in 2006 in Beijing and the greater wet deposition of ammonium compared to sulfate and nitrate in 2005 in Chongqing. Furthermore, simultaneous increase of PM2.5 acidity was observed from spring to early summer of 2005 in both cities. This synoptic-scale evolution of PM2.5 acidity was accompanied by the changes in air masses origins, which were influenced by the movements of a subtropical high over the northwestern Pacific in early summer. Finally, the correlations between [NO3−]/[SO42−] and [NH4+]/[SO42−] suggests that under conditions of high aerosol acidity, heterogeneous reactions became one of the major pathways for the formation of nitrate at both cities. These findings provided new insights in our understanding of the spatial and temporal variations in aerosol acidity in Beijing and Chongqing, as well as those reported in other cities in China.

scholarly journals Spatial and temporal distribution of phytoplankton in Lake Skadar

2012 ◽  
Vol 64 (2) ◽  
pp. 585-595 ◽  
Author(s):  
Jelena Rakocevic
Keyword(s):  
Spatial Heterogeneity ◽  
Phytoplankton Community ◽  
General Pattern ◽  
Seasonal Succession ◽  
Temporal Distribution ◽  
Late Summer ◽  
Early Summer ◽  
Quantitative Composition ◽  
Autumn And Winter ◽  
Lake Skadar

Phytoplankton seasonal succession and spatial heterogeneity were studied in Lake Skadar from February to December 2004. A total of 167 taxa from 6 algal divisions were observed, with Bacillariophyta being best represented (52.8%). The general pattern of phytoplankton seasonal succession in Lake Skadar was: Bacillariophyta in the spring, Chlorophyta in early summer, Cyanobacteria and Chlorophyta in late summer and Bacillariophyta and Chlorophyta in autumn and winter. Distinct spatial heterogeneity was observed. The central, open part of the lake (pelagic zone) was characterized by dominant euplanktonic species, mostly diatoms, whereas the western and northwestern parts (more isolated and shallower) had higher abundance of greens and blue-greens and a higher percentage of resuspended benthic-epiphytic forms in the phytoplankton community. Comparison with former phytoplankton data showed distinct differences in terms of the qualitative and quantitative composition of the phytoplankton community of Lake Skadar, which indicates lake deterioration.

scholarly journals Passive microwave-derived spatial and temporal variations of summer melt on the Greenland ice sheet

1993 ◽  
Vol 17 ◽  
pp. 233-238 ◽  
Author(s):  
Thomas L. Mote ◽  
Mark R. Anderson ◽  
Karl C. Kuivinen ◽  
Clinton M. Rowe
Keyword(s):  
Time Series ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Late Summer ◽  
Temporal Variations ◽  
Early Summer ◽  
Passive Microwave ◽  
Brightness Temperatures ◽  
Surface Melt ◽  
Major Surface

Passive microwave-brightness temperatures over the Greenland ice sheet are examined during the melt season in order to develop a technique for determining surface-melt occurrences. Time series of Special Sensor Microwave/ Imager (SSM/I) data are examined for three locations on the ice sheet, two of which are known to experience melt. These two sites demonstrate a rapid increase in brightness temperatures in late spring to early summer, a prolonged period of elevated brightness temperatures during the summer, and a rapid decrease in brightness temperatures during late summer. This increase in brightness temperatures is associated with surface snow melting. An objective technique is developed to extract melt occurrences from the brightness-temperature time series. Of the two sites with summer melt, the site at the lower elevation had a longer period between the initial and final melt days and had more total days classified as melt during 1988 and 1989. The technique is then applied to the entire Greenland ice sheet for the first major surface-melt event of 1989. The melt-zone signal is mapped from late May to early June to demonstrate the advance and subsequent retreat of one “melt wave”. The use of such a technique to determine melt duration and extent for multiple years may provide an indication of climate change.

Long-term dynamics of natural populations of Schistosoma mansoni among Rattus rattus in patchy environment

Parasitology ◽  
1992 ◽  
Vol 104 (2) ◽  
pp. 291-298 ◽  
Author(s):  
A. Théron ◽  
J. P. Pointier ◽  
S. Morand ◽  
D. Imbert-Establet ◽  
G. Borel
Keyword(s):  
Schistosoma Mansoni ◽  
Rattus Rattus ◽  
Natural Populations ◽  
Ecological Factors ◽  
Temporal Variations ◽  
Distribution Analysis ◽  
Patchy Environment ◽  
Human Parasite ◽  
Spatio Temporal

SUMMARYDynamics of natural populations of Schistosoma mansoni were studied during 8 consecutive years among Rattus rattus populations from 8 transmission sites of the marshy forest focus of Guadeloupe (French West Indies). The schistosome population is over-dispersed (k = 0·119) within the murine hosts and ecological factors linked to the patchy environment may be responsible for such aggregated distribution. Analysis of the spatio-temporal variations in prevalences, intensities and abundances showed limited variations of the infection during the 8 years at the level of the whole parasite population but great spatial heterogeneity at the level of local schistosome populations. Inter-populational genetic variability linked to the degree of adaptation of this human parasite to the murine host may explain differences in transmission dynamics between the local populations of S. mansoni.

Effect of the Leeuwin Current upon sea surface temperatures off south-western Australia

1984 ◽  
Vol 35 (4) ◽  
pp. 487 ◽  
Author(s):  
DJ Rochford
Keyword(s):  
Western Australia ◽  
Coastal Waters ◽  
Sea Surface ◽  
Sea Surface Temperatures ◽  
Leeuwin Current ◽  
South Eastern ◽  
Surface Temperatures ◽  
Autumn And Winter

Comparison of long-term mean monthly sea surface temperatures of coastal waters at comparable latitudes off south-eastern and south-westem Australia shows that, during the duration of the Leeuwin Current in autumn and winter, sea surface temperatures are 1-3�C higher off south-western Australia.

scholarly journals Wave spectral shapes in the coastal waters based on measured data off Karwar, west coast of India

2017 ◽  
Author(s):  
M. Anjali Nair ◽  
V. Sanil Kumar
Keyword(s):  
Wave Height ◽  
Coastal Waters ◽  
High Frequency ◽  
Significant Wave Height ◽  
Wave Spectrum ◽  
Temporal Variations ◽  
Wave Spectra ◽  
Monsoon Period ◽  
Significant Wave ◽  
Spectral Shapes

Abstract. Understanding of the wave spectral shapes is of primary importance for the design of marine facilities. In this paper, the wave spectra collected from January 2011 to December 2015 in the coastal waters are examined to know the temporal variations in the wave spectral shape. For 31.15 % of the time, peak frequency is between 0.08 and 0.10 Hz and the significant wave height is also relatively high (~ 1.55 m) for waves in this class. The slope of the high-frequency tail of the monthly average wave spectra is high during the Indian summer monsoon period (June–September) compared to other months and it increases with increase in significant wave height. There is no much interannual variation in slope for swell dominated spectra during the monsoon, while in the non-monsoon period when wind-seas have much influence, the slope varies significantly. Since the high-frequency slope of the wave spectrum is within the range 3–4 during the monsoon period, Donelan spectrum shows better fit for the wave spectra in monsoon months compared to other months.

Seasonal changes in glucose tolerance and glycogen disposition in a lizard

1963 ◽  
Vol 204 (4) ◽  
pp. 677-680 ◽  
Author(s):  
Anthony Di Maggio ◽  
Herbert C. Dessauer
Keyword(s):  
Blood Glucose ◽  
Glucose Tolerance ◽  
Seasonal Changes ◽  
Liver Glycogen ◽  
Early Summer ◽  
Anolis Carolinensis ◽  
Fasting Level ◽  
Glucose Injection ◽  
Different Seasons ◽  
Autumn And Winter

Forty milligrams of glucose in 0.4 ml of water were injected intraperitoneally into fasted adult male lizards, Anolis carolinensis, in different seasons. At intervals of 3 hr to 5 days following injection lizards were sacrificed and their tissues analyzed for carbohydrate. Blood glucose returned to fasting level in less than 36 hr in spring and summer but remained above fasting level for over 2 days during autumn and winter. Generally, 4–6 g of glycogen were deposited per 100 g of liver per day. Greater quantities of glycogen were deposited in liver during autumn than in other seasons. The rate of decrease of liver glycogen was slowest in autumn and winter. Extrahepatic glycogen did not increase after glucose injection in early summer and autumn but rose significantly in winter and spring. The decreased "glucose tolerance" of Anolis and its increased capacity to store glycogen in autumn and winter may be due to a decreased rate of carbohydrate oxidation in these seasons.

Variations in marsh surface levels in the upper Tay Estuary

1987 ◽  
Vol 92 (3-4) ◽  
pp. 345-358
Author(s):  
J. McManus ◽  
S. A. K. Alizai
Keyword(s):  
Surface Sediments ◽  
Marsh Surface ◽  
Early Summer ◽  
Phragmites Communis ◽  
Accretion Rates ◽  
Marsh Sediments ◽  
Juncus Gerardi ◽  
Autumn And Winter ◽  
Intertidal Mud Flats ◽  
Tay Estuary

SynopsisIn the upper Tay Estuary the marshes bordering the northern intertidal mud-flats are dominated by Phragmites communis in the west, with Juncus gerardi becoming more important eastwards, where Aster tripolium is also significant. Sedimentation on the surface of the marshes at Kingoodie and Invergowrie has been measured at monthly intervals over a twenty-three month period, using stake implants to provide local marker levels. The marsh surfaces were at their greatest heights in early summer and fell during autumn and winter. Maximum accretion rates were measured in spring on the outer marshes at both sites, where net accretion over the entire period was greatest. The net accretion in the Phragmites marsh was 2.5 mm, in the Aster belt 5 mm, in established Juncus 9 mm and in newly colonising Juncus 8.7 mm, whereas on the adjacent Kingoodie mud flats there was net stability over the twenty-three-month interval. Accretion was less at Invergowrie (3–5 mm) than at Kingoodie (2.5–9 mm). Monthly analysis of the upper 0.5 cm of the surface sediments showed the Invergowrie marsh sediments to be sandier than those of Kingoodie. Silts and clays deposited on the outer marsh surface in spring migrate landward during the summer and autumn. The apparent annual net accretion varied greatly with the specific month used for comparison, with 13 mm net losses based on November figures and 10 mm gains using January data.

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