Seasonal Distribution and Abundance of Dugongs in the Western-Gulf-of-Carpentaria

Aerial surveys of coastal waters (27 216 km2) in the western Gulf of Carpentaria during the dry season of 1984 and wet season of 1985 indicated no major seasonal changes in distribution and relative abundance of dugongs. Minimum population size in the dry season was estimated as 16 816 � 2946 (standard error), with a relative density of 0.62 k 0.11 km-2, and that for the wet season 16 846 + 3257, with a relative density of 0.62 � 0.12 km-2. The estimates exclude 5% of observations which could have been either dugongs or Irrawaddy dolphins, and were corrected for submerged dugongs and those missed on the surface. Dugongs were unevenly distributed over the study area, and neither mean group size nor proportion of calves varied between seasons. Dugong abundance was correlated with area of available seagrass. The catch rate of dugongs by Aboriginal people off Numbulwar decreased six-fold between the 1960s and 1985 (60 to 10 p.a.), possibly due to excessive hunting.

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Temporal Variations of Submarine Groundwater Discharge into a Tide-Dominated Coastal Wetland (Gaomei Wetland, Western Taiwan) Indicated by Radon and Radium Isotopes

Water ◽

10.3390/w12061806 ◽

2020 ◽

Vol 12 (6) ◽

pp. 1806 ◽

Cited By ~ 1

Author(s):

Feng-Hsin Hsu ◽

Chih-Chieh Su ◽

Pei-Ling Wang ◽

In-Tian Lin

Keyword(s):

Coastal Waters ◽

Seasonal Changes ◽

Submarine Groundwater Discharge ◽

Coastal Wetland ◽

Groundwater Discharge ◽

High Tide ◽

Dry Season ◽

Wet Season ◽

Submarine Groundwater ◽

Δd And Δ18o

Submarine groundwater discharge (SGD) is evidenced around Taiwan, but the seasonal/temporal changes of SGD have not been fully examined. Here, we report a time-series investigation of SGD into a tide-dominated coastal wetland, the Gaomei Wetland, located to the south of the Da-Chia River’s mouth, western Taiwan, by using environmental tracers (222Rn, 224Raex, 228Ra, δD, and δ18O). Our results showed that regardless of dry and wet seasons, the 222Rn activities in coastal waters were high at low tide but low at high tide. It represents the continuous input of 222Rn-enriched groundwater. However, the 224Raex and 228Ra activities showed seasonal changes with tide conditions. In the dry season, the 224Raex and 228Ra activities in coastal waters were low at low tide but high at high tide; whereas in the wet season, an opposite relation was observed with quite high 224Raex and 228Ra activities in the low-tide waters. Coupled with the lower δD and δ18O values of coastal and pore waters in the dry season, in comparison to those in the wet season, it is suggested that these phenomena probably reflected a seasonal difference in the main SGD component with fresh SGD in the dry season, but saline ones in the wet season. Based on a 222Rn mass balance model, the estimated SGD fluxes into the Gaomei Wetland varied with tidal fluctuations and ranged from 0.2 to 25 cm d−1 and from 0.1 to 47 cm d−1 for the dry and wet seasons, respectively. A slightly high SGD flux occurring during the wet season at spring tide, implied a stronger tidal pumping coupled with a larger hydraulic gradient between land and sea. In this study, we demonstrated that the variation of SGD into the Gaomei Wetland is not only controlled by the seasonal changes of groundwater recharge, but also by the tidal pumping process.

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Seasonal-Changes in Relative Abundance and Spatial-Distribution of Australian Lowland Tropical Satyrine Butterflies

Australian Journal of Zoology ◽

10.1071/zo9950209 ◽

1995 ◽

Vol 43 (3) ◽

pp. 209 ◽

Cited By ~ 10

Author(s):

MF Braby

Keyword(s):

Spatial Distribution ◽

Relative Abundance ◽

Seasonal Changes ◽

Dry Season ◽

Seasonal Abundance ◽

Rainfall Regime ◽

Peak Activity ◽

Wet Season ◽

Tropical Zone ◽

Early Afternoon

Seven species of grass-feeding satyrine butterflies (Lepidoptera : Nymphalidae) coexist in lowland regions of the wet tropical zone of north-eastern Queensland, Australia. Their seasonal changes in relative abundance, spatial distribution and diurnal activities were monitored at Cardwell (18 degrees 16'S) during 1989-92, with particular emphasis placed on three species of Mycalesis. The climate at Cardwell is monsoonal, being characterised by high summer rainfall and an annual winter dry season that lasts about seven months on average (although usually some rain falls during this period). Rainfall is quite variable in terms of both the timing and magnitude of the wet season. In general, relative abundance of adult Mycalesis species, increased during the early dry season, peaked during the dry winter months, decreased in the late dry season and then reached very low levels with the first significant wet-season rainfall. The pattern of seasonal abundance was broadly synchronous with seasonal changes in grass moisture content, which in turn was linked with rainfall regime. Ypthima arctous, Hypocysta irius and H. adiante showed seasonal fluctuations similar to those of Mycalesis but numbers of Melanitis leda peaked at the end of the dry season before the first significant rainfall. The seven satyrines also showed pronounced spatial and temporal differentiation in habitat distribution and timing of peak flight activity in the late dry season. Mycalesis terminus predominated in rainforest edge and adults were most active from late morning to early afternoon, whereas My. perseus and My. sirius occurred in the more open areas, favouring open eucalypt forest and paperbark woodland (Melaleuca swampland), respectively. Peak activity of My. perseus and My. sirius was confined largely to early morning and late afternoon, while Me. leda was strictly crepuscular. Peak activity of Y. arctous coincided with that of My. terminus but, unlike H. irius, which occurred only in rainforest edge, Y. arctous favoured the less shaded habitat of paperbark woodland. It is likely that adults of all species move seasonally and contract to moist refugia in the late dry season. The patterns of seasonality in Mycalesis may be influenced by variation in rainfall, and hence larval food quality, but other factors likely to influence fluctuation in abundance are briefly discussed.

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The seasonal changes of the gut microbiome of the population living in traditional lifestyles are represented by characteristic species-level and functional-level SNP enrichment patterns

BMC Genomics ◽

10.1186/s12864-021-07372-0 ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

Xue Zhu ◽

Jiyue Qin ◽

Chongyang Tan ◽

Kang Ning

Keyword(s):

Gut Microbiome ◽

Seasonal Changes ◽

Dry Season ◽

Urban Setting ◽

Snp Analysis ◽

Wet Season ◽

Human Gut ◽

Human Gut Microbiome ◽

Genome Level ◽

Prevalent Species

Abstract Background Most studies investigating human gut microbiome dynamics are conducted on humans living in an urban setting. However, few studies have researched the gut microbiome of the populations living traditional lifestyles. These understudied populations are arguably better subjects in answering human-gut microbiome evolution because of their lower exposure to antibiotics and higher dependence on natural resources. Hadza hunter-gatherers in Tanzania have exhibited high biodiversity and seasonal patterns in their gut microbiome composition at the family level, where some taxa disappear in one season and reappear later. Such seasonal changes have been profiled, but the nucleotide changes remain unexplored at the genome level. Thus, it is still elusive how microbial communities change with seasonal changes at the genome level. Results In this study, we performed a strain-level single nucleotide polymorphism (SNP) analysis on 40 Hadza fecal metagenome samples spanning three seasons. With more SNP presented in the wet season, eight prevalent species have significant SNP enrichment with the increasing number of SNP calling by VarScan2, among which only three species have relatively high abundances. Eighty-three genes have the most SNP distributions between the wet season and dry season. Many of these genes are derived from Ruminococcus obeum, and mainly participated in metabolic pathways including carbon metabolism, pyruvate metabolism, and glycolysis. Conclusions Eight prevalent species have significant SNP enrichments with the increasing number of SNP, among which only Eubacterium biforme, Eubacterium hallii and Ruminococcus obeum have relatively high species abundances. Many genes in the microbiomes also presented characteristic SNP distributions between the wet season and the dry season. This implies that the seasonal changes might indirectly impact the mutation patterns for specific species and functions for the gut microbiome of the population that lives in traditional lifestyles through changing the diet in wet and dry seasons, indicating the role of these variants in these species’ adaptation to the changing environment and diets.

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Seasonal changes in water quality and macrophytes and the impact of cattle on tropical floodplain waterholes

Marine and Freshwater Research ◽

10.1071/mf12114 ◽

2012 ◽

Vol 63 (9) ◽

pp. 788 ◽

Cited By ~ 17

Author(s):

N. E. Pettit ◽

T. D. Jardine ◽

S. K. Hamilton ◽

V. Sinnamon ◽

D. Valdez ◽

...

Keyword(s):

Water Quality ◽

Seasonal Changes ◽

Aquatic Macrophyte ◽

Plant Cover ◽

Critical Role ◽

Dry Season ◽

Nutrient Concentrations ◽

Wet Season ◽

Dry Tropics ◽

The Impact

The present study indicates the critical role of hydrologic connectivity in floodplain waterholes in the wet–dry tropics of northern Australia. These waterbodies provide dry-season refugia for plants and animals, are a hotspot of productivity, and are a critical part in the subsistence economy of many remote Aboriginal communities. We examined seasonal changes in water quality and aquatic plant cover of floodplain waterholes, and related changes to variation of waterhole depth and visitation by livestock. The waterholes showed declining water quality through the dry season, which was exacerbated by more frequent cattle usage as conditions became progressively drier, which also increased turbidity and nutrient concentrations. Aquatic macrophyte biomass was highest in the early dry season, and declined as the dry season progressed. Remaining macrophytes were flushed out by the first wet-season flows, although they quickly re-establish later during the wet season. Waterholes of greater depth were more resistant to the effects of cattle disturbance, and seasonal flushing of the waterholes with wet-season flooding homogenised the water quality and increased plant cover of previously disparate waterholes. Therefore, maintaining high levels of connectivity between the river and its floodplain is vital for the persistence of these waterholes.

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Diversity, distribution and relative abundance of avifauna at Ansas Dam and surrounding farmland site Debre Berhan Town, Ethiopia

Avian Biology Research ◽

10.1177/1758155920963200 ◽

2020 ◽

pp. 175815592096320

Author(s):

Alemayehu Shiferaw ◽

Dereje Yazezew

Keyword(s):

Relative Abundance ◽

Bird Species ◽

Dry Season ◽

Avian Species ◽

Ordinal Scale ◽

Line Transect ◽

Wet Season ◽

Debre Berhan ◽

Dry Seasons ◽

Wet And Dry Seasons

The diversity, distribution, and relative abundance of avifauna were studied at and Around Ansas Dam, Debre Berhan Town, Ethiopia, from early September 2018 to early February 2019, covering both wet and dry seasons. Line transect technique was employed to study the diversity, abundance and distribution of birds species in the farmland site while total count employed on the dam. Data were collected in both wet and dry seasons from 6:30 to10:00 early morning and 15:30 to 18.00 late afternoon, when birds are more active. The data were analyzed with Shannon-Weiner Index, Simpson Index, Evenness Index, and relative abundance. A total of 45 bird species (35 in the dam and 22 in the farmland) belonging to nine orders and 21 families were recorded during the study period. Order Passeriformes (37.8%) followed by order Charadriformes (24.4%) were represented highest number. From all identified species at Ansas Dam and surrounding farmland, Abyssinian longclaw, Black-headed siskins, White-tailed swallow, Blue-winged goose, and Spot-breasted lapwing were endemic birds to Ethiopia. The highest Shannon diversity (H′ = 2.1) was recorded in dam during the dry season while the lowest (H′ = 1.78) was recorded during wet season in farmland. However, the Simpson diversity Index of avian species indicated relatively higher avian species diversity during the dry season in dam (D = 0.80) than farmland (D = 0.71) habitat. Evenness was highest in the dam (E = 0.65) and lowest in the farmland (E = 0.58) habitat. More avian species similarity (SI = 0.42) at farmland and dam habitat during the wet season but least similarity (SI = 0.2) was observed during the dry season. Most birds had scored rare in the ordinal scale while few species with abundant and uncommon ranks in both habitats and seasons. Conservation of the different charismatic bird species should be taken as an important component of wildlife management plan in the area.

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DISSOLVED SILICATE IN COASTAL WATER OF SOUTH SULAWESI

Jurnal Ilmu dan Teknologi Kelautan Tropis ◽

10.29244/jitkt.v6i2.9022 ◽

2015 ◽

Vol 6 (2) ◽

Author(s):

Muhammad Lukman ◽

Andriani Nasir ◽

Khairul Amri ◽

Rahmadi Tambaru ◽

Muhammad Hatta ◽

...

Keyword(s):

Water Quality ◽

Chlorophyll A ◽

Coastal Water ◽

Coastal Waters ◽

Dry Season ◽

Limiting Factor ◽

Western Coast ◽

Wet Season ◽

South Sulawesi ◽

Dissolved Silicate

ABSTRACT Dissolved silicate (DSi) in coastal waters plays a crucial role in phytoplankton growth particularly diatom. This study aimed to determine DSi concentration seasonally in waters of the western coast of South Sulawesi in relation to coastal water quality indicator. Water, chlorophyll-a, and diatom samples were collected from the coastal areas of the Tallo-Makassar, Maros, and Pangkep, in April 2013 (transitional season), June 2013 (dry season), and February 2014 (wet season). Factorial analysis of variance was used to identify significant seasonal and temporal variations, and linear regression was used to test the relationship of chlorophyll-a and diatom abundance to DSi concentrations. The results showed that the DSi concentration was higher in the wet season of 35.2-85.2 µM than in the other seasons (transitional season: 10.8-68.4 µM, dry season: 9.59-24.1 µM). The abundance of diatoms during the transitional season reached ~9.7x107 cell/m3 in the Pangkep river, 2.3x107 cell/m3 in the Tallo river, and 1.3 x 107 cell/m3 in the Maros river. Chaetoceros, Nitzschia, and Rhizosolenia dominated the diatom composition. The mean concentration of chlorophyll-a in the Makassar coastal waters was 4.52±4.66 mg/m3, while in the Maros and Pangkep waters of 1.40±1.06, and 2.72±1.94 mg/m3, respectively. There was no strong linear corelation between DSi and diatom abundances, nor chlorophyll-a. These results suggested that DSi become a non-limiting factor for the diatom growth and potentially reduce the water quality via eutrophication and diatom blooms. Keywords: dissolved silicate, diatom, chlorophyll-a, coastal waters, South Sulawesi

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DISSOLVED SILICATE IN COASTAL WATER OF SOUTH SULAWESI

Jurnal Ilmu dan Teknologi Kelautan Tropis ◽

10.28930/jitkt.v6i2.9022 ◽

2015 ◽

Vol 6 (2) ◽

Author(s):

Muhammad Lukman ◽

Andriani Nasir ◽

Khairul Amri ◽

Rahmadi Tambaru ◽

Muhammad Hatta ◽

...

Keyword(s):

Water Quality ◽

Chlorophyll A ◽

Coastal Water ◽

Coastal Waters ◽

Dry Season ◽

Limiting Factor ◽

Western Coast ◽

Wet Season ◽

South Sulawesi ◽

Dissolved Silicate

ABSTRACT Dissolved silicate (DSi) in coastal waters plays a crucial role in phytoplankton growth particularly diatom. This study aimed to determine DSi concentration seasonally in waters of the western coast of South Sulawesi in relation to coastal water quality indicator. Water, chlorophyll-a, and diatom samples were collected from the coastal areas of the Tallo-Makassar, Maros, and Pangkep, in April 2013 (transitional season), June 2013 (dry season), and February 2014 (wet season). Factorial analysis of variance was used to identify significant seasonal and temporal variations, and linear regression was used to test the relationship of chlorophyll-a and diatom abundance to DSi concentrations. The results showed that the DSi concentration was higher in the wet season of 35.2-85.2 µM than in the other seasons (transitional season: 10.8-68.4 µM, dry season: 9.59-24.1 µM). The abundance of diatoms during the transitional season reached ~9.7x107 cell/m3 in the Pangkep river, 2.3x107 cell/m3 in the Tallo river, and 1.3 x 107 cell/m3 in the Maros river. Chaetoceros, Nitzschia, and Rhizosolenia dominated the diatom composition. The mean concentration of chlorophyll-a in the Makassar coastal waters was 4.52±4.66 mg/m3, while in the Maros and Pangkep waters of 1.40±1.06, and 2.72±1.94 mg/m3, respectively. There was no strong linear corelation between DSi and diatom abundances, nor chlorophyll-a. These results suggested that DSi become a non-limiting factor for the diatom growth and potentially reduce the water quality via eutrophication and diatom blooms. Keywords: dissolved silicate, diatom, chlorophyll-a, coastal waters, South Sulawesi

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Contrasting patterns of litterfall seasonality and seasonal changes in litter decomposability in a tropical rainforest region

Biogeosciences Discussions ◽

10.5194/bgd-11-7901-2014 ◽

2014 ◽

Vol 11 (6) ◽

pp. 7901-7929

Author(s):

S. A. Parsons ◽

V. Valdez-Ramirez ◽

R. A. Congdon ◽

S. E. Williams

Keyword(s):

Seasonal Changes ◽

Biogeochemical Cycles ◽

Dry Season ◽

Tropical Region ◽

Soil N ◽

Wet Season ◽

Evergreen Forests ◽

P Limitation ◽

Global Trend ◽

The Difference

Abstract. The seasonality of litter inputs in forests has important implications for understanding ecosystem processes and biogeochemical cycles. We quantified the drivers of seasonality in litterfall and leaf decomposability, using plots throughout the Australian wet tropical region. Litter fell mostly in the summer (wet, warm) months in the region, but other peaks occurred throughout the year. Litterfall seasonality was modelled well with the level of deciduousness of the site (plots with more deciduous species had lower seasonality than evergreen plots), temperature (higher seasonality in the uplands), disturbance (lower seasonality with more early secondary species) and soil fertility (higher seasonality with higher N : P/P limitation) (SL total litterfall model 1 = deciduousness + soil N : P + early secondary sp: r2 = 0.63, n = 30 plots; model 2 = temperature + early secondary sp. + soil N : P: r2 = 0.54, n = 30; SL leaf = temperature + early secondary sp. + rainfall seasonality: r2 = 0.39, n = 30). Leaf litter decomposability was lower in the dry season than in the wet season, driven by higher phenolic concentrations in the dry, with the difference exacerbated particularly by lower dry season moisture. Our results are contrary to the global trend for tropical rainforests; in that seasonality of litterfall inputs were generally higher in wetter, cooler, evergreen forests, compared to generally drier, warmer, semi-deciduous sites that had more uniform monthly inputs. We consider this due to more diverse litter shedding patterns in semi-deciduous and raingreen rainforest sites, and an important consideration for ecosystem modellers. Seasonal changes in litter quality are likely to have impacts on decomposition and biogeochemical cycles in these forests due to the litter that falls in the dry being more recalcitrant to decay.

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Distribution and Abundance of Ducks in the Alligator Rivers Region, Northern Territory

Wildlife Research ◽

10.1071/wr9900573 ◽

1990 ◽

Vol 17 (6) ◽

pp. 573 ◽

Cited By ~ 18

Author(s):

SR Morton ◽

KG Brennan ◽

MD Armstrong

Keyword(s):

Northern Territory ◽

Dry Season ◽

Correction Factors ◽

The South ◽

Wet Season ◽

Aerial Surveys ◽

Black Duck

Aerial surveys between 1981 and 1984 were used to identify monthly trends in the abundance of wandering whistling-duck Dendrocygna arcuata, plumed whistling-duck D. eytoni, radjah shelduck Tadorna radjah, Pacific black duck Anas superciliosa, and grey teal A. gibberifrons on five floodplains of the Alligator Rivers region, 250 km east of Darwin in the monsoonal north of the Northern Territory. Ground surveys were conducted during the same period on one of the floodplains, the Magela plain, to provide more detailed information. The Magela floodplain was inhabited by few ducks during the wet season (November to March), but numbers then increased to dramatic peaks in the late dry season. The Nourlangie floodplain and Boggy Plain (a large backswamp of the South Alligator floodplain) showed similar patterns, but the numbers of ducks were usually fewer. Ducks were uncommon on the shallower East Alligator and Cooper floodplains except for relatively brief periods in the wet season. The ground surveys suggested that ducks sought out the persistent swamps that characterise the Magela floodplain in the dry season. Ground surveys also indicated that aerial surveys underestimated densities; on the basis of correction factors calculated from the ground surveys, peak numbers on the five floodplains were roughly estimated to be 400 000 wandering whistling-ducks, 70 000 plumed whistling-ducks, 20 000 radjah shelducks, 50 000 Pacific black ducks, and 50 000 grey teal. Pink-eared ducks Malacorhynchus membranaceus and hardhead Aythya australis were recorded sporadically in low numbers. The Alligator Rivers region acted as a dry season refuge for large concentrations of ducks because of the atypical persistence of freshwaters on the Magela and Nourlangie floodplains and some of the backswamps of the South Alligator, such as Boggy Plain. The large aggregations appear to be unique in Australia.

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The ecology of small mammals in Ogba Forest Reserve, Nigeria

Journal of Tropical Ecology ◽

10.1017/s0266467400003217 ◽

1989 ◽

Vol 5 (1) ◽

pp. 51-64 ◽

Cited By ~ 7

Author(s):

John Giobaguan Iyawe

Keyword(s):

Small Mammals ◽

Seasonal Changes ◽

Common Species ◽

Dry Season ◽

Small Rodents ◽

Wet Season ◽

Forest Reserve ◽

Percentage Composition ◽

Monthly Variations ◽

Arvicanthis Niloticus

ABSTRACTA total of 392 small mammals belonging to five species of small rodents and four species of shrews were caught. The small mammals and their percentage composition were Crocidura nigeriae (20.9%), Crocidura grandiceps (11.7%), Crocidura crossei (9.7%), Crocidura flavescens manni (20.4%), Mus musculoides (39.0%), Praomys tullbergi (11.5%), Lophuromys sikapusi (3.6%), Lemniscomys striatus (1.3%), and Arvicanthis niloticus (0.3%).There were monthly variations in the number of Mus musculoides and Crocidura nigeriae.In Mus musculoides breeding was at a maximum at the beginning and towards the end of the wet season and early dry season. In Crocidura nigeriae breeding was maximal during the wet season and low in the dry season.The seasonal changes in the age structure of the two most common species: Mus musculoides and Crocidura nigeriae, are described.

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