Limnological survey of eight billabongs in the Magela Creek catchment, Northern Territory

BT Hart; RJ McGregor

doi:10.1071/mf9800611

Limnological survey of eight billabongs in the Magela Creek catchment, Northern Territory

Marine and Freshwater Research ◽

10.1071/mf9800611 ◽

1980 ◽

Vol 31 (5) ◽

pp. 611 ◽

Cited By ~ 33

Author(s):

BT Hart ◽

RJ McGregor

Keyword(s):

Dissolved Oxygen ◽

Chlorophyll A ◽

Bottom Water ◽

Northern Territory ◽

Dry Season ◽

Wet Season ◽

Sodium Potassium ◽

Phosphate Nitrate ◽

Bottom Waters ◽

Limnological Survey

A 6-week survey of the physicochemical limnology of eight billabongs in the Magela Creek catchment of the Northern Territory was conducted between December 1977 and January 1978. This covered the important period corresponding to the end of the dry season and the commencement of the wet season. Each billabong was sampled approximately weekly. At the end of the dry season. the billabongs' waters had elevated conductivity and turbidity, and generally higher sodium, potassium. chloride, phosphate, nitrate and chlorophyll a concentrations. They were generally slightly acidic and. in some. the bottom water was anaerobic. With the commencement of the wet season. the billabongs were flushed and a significant improvement in water quality was noted. Temperature. dissolved oxygen and redox potential data were used to tentatively classify these billabongs as polymictic. Under certain circumstances mixing did not occur for several days. during which time the bottom waters became significantly depleted in dissolved oxygen. On the basis of limited nutrient and chlorophyll a data, the billabongs at the end of the dry season appear to be mesotrophic.

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Thinking honeyeater: nectar maps for the Northern Territory, Australia

Pacific Conservation Biology ◽

10.1071/pc000061 ◽

2000 ◽

Vol 6 (1) ◽

pp. 61 ◽

Cited By ~ 35

Author(s):

John C. Z. Woinarski ◽

Greg Connors ◽

Don C. Franklin

Keyword(s):

Northern Territory ◽

Dry Season ◽

Spatial And Temporal Variation ◽

Wet Season ◽

Nectar Production ◽

The World ◽

Eucalypt Forests ◽

The Times ◽

Species Specific ◽

Nectar Availability

We create monthly maps of nectar availability for the 1.4 x 106 km2 jurisdiction of the Northern Territory, Australia. These are based on a combination of vegetation mapping and a series of indices of plant species specific nectar scoring. The maps reveal complex spatial and temporal variation in nectar availability, but most notably a greater nectar resource in the monsoon-influenced north than in the arid south, and a peak in nectar availability in the dry season. The latter is associated with the extensive tropical eucalypt forests (especially those co-dominated by Eucalyptus miniata and E. tetrodonta). In contrast, wet season nectar availability in these forests is limited, but riparian and swampland forests, typically dominated by Melaleuca species, provide rich but spatially restricted nectar resources. The extensive and rich nectar resources available in eucalypt forests in the dry season supplement the diets of many species which are not primarily nectarivorous. This resource helps shape the singularity of northern Australian eucalypt forests relative to other extensive forests elsewhere in the world. Nectarivores remain in the system through a combination of movements across a number of scales, habitat shifting, and diet shifting. The latter is aided by the peaking of invertebrate and fruit resources at the times of minimum nectar production; a shuffling in resource availability brought about by the extreme climatic seasonality.

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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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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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ANALYSIS OF WATER PRODUCTIVITY IN THE BANDA SEA BASED ON REMOTE SENSING SATELLITE DATA

International Journal of Remote Sensing and Earth Sciences (IJReSES) ◽

10.30536/j.ijreses.2020.v17.a3280 ◽

2020 ◽

Vol 17 (1) ◽

pp. 25

Author(s):

Sartono Marpaung ◽

Risky Faristyawan ◽

Anang Dwi Purwanto ◽

Wikanti Asriningrum ◽

Argo Galih Suhada ◽

...

Keyword(s):

Chlorophyll A ◽

El Niño ◽

El Nino ◽

Dry Season ◽

La Niña ◽

Wet Season ◽

Conservation Areas ◽

Conservation Area ◽

Chlorophyll A Concentration ◽

La Nina

Abstract. This study examines the density of potential fishing zone (PFZ) points and chlorophyll-a concentration in the Banda Sea. The data used are those on chlorophyll-a from the Aqua MODIS satellite, PFZ points from ZAP and the monthly southern oscillation index. The methods used are single image edge detection, polygon center of mass, density function and a Hovmoller diagram. The result of the analysis show that productivity of chlorophyll-a in the Banda Sea is influenced by seasonal factors (dry season and wet season) and ENSO phenomena (El Niño and La Niña). High productivity of chlorophyll-a occurs during in the dry season with the peak in August, while low productivity occurs in the wet season and the transition period, with the lowest levels in April and December. The variability in chlorophyll-a production is influenced by the global El Niño and La Niña phenomena; production increases during El Niño and decreases during La Niña. Tuna conservation areas have as lower productivity of chlorophyll-a and PFZ point density compared to the northern and southern parts of the Banda Sea. High density PFZ point regions are associated with regions that have higher productivity of chlorophyll-a, namely the southern part of the Banda Sea, while low density PFZ point areas are associated with regions that have a low productivity of chlorophyll-a, namely tuna conservation areas. The effect of the El Niño phenomenon in increasing chlorophyll-a concentration is stronger in the southern part of study area than in the tuna conservation area. On the other hand, the effect of La Niña phenomenon in decreasing chlorophyll-a concentration is stronger in the tuna conservation area than in the southern and northern parts of the study area.

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Seasonal use of savanna landscapes by the Gouldian finch, Erythrura gouldiae, in the Yinberrie Hills area, Northern Territory

Wildlife Research ◽

10.1071/wr00049 ◽

2001 ◽

Vol 28 (4) ◽

pp. 445 ◽

Cited By ~ 40

Author(s):

P. L. Dostine ◽

G. C. Johnson ◽

D. C. Franklin ◽

Y. Zhang ◽

C. Hempel

Keyword(s):

Full Range ◽

Northern Territory ◽

Dry Season ◽

Perennial Grasses ◽

Grass Species ◽

Wet Season ◽

Themeda Triandra ◽

Annual Grasses ◽

Gouldian Finch ◽

Hills Area

The diet, attributes of feeding sites and patterns of seasonal movements of a population of the Gouldian finch, Erythrura gouldiae, were studied in the Yinberrie Hills area north of Katherine in the Northern Territory. In the dry season (April–November) Gouldian finches foraged mostly on burnt ground and fed on exposed seed of annual grasses, especially seed of spear-grass, Sorghum spp. In the wet season (December–March) Gouldian finches fed on seed of a sequence of perennial grass species, including Themeda triandra, Alloteropsis semialata, Chrysopogon fallax and Heteropogon triticeus. Gouldian finches undertake regular seasonal shifts in habitat, from breeding areas in hill woodland in the dry season to adjacent lowlands throughout much of the wet season, in response to seasonal changes in food availability. There is an annual pulse in abundance of fallen seed in the early dry season that is depleted to near zero levels by germination of annual grasses early in the wet season. Thereafter, finches depend on seed from other sources, principally ripe and ripening seed of perennial grasses. Observations over three successive wet seasons suggest that Gouldian finches track seed resources provided by seeding perennial grasses over an extensive area of lowland grassy woodland adjacent to the breeding area, favouring small patches of grassy woodland for brief periods until seed fall. There were subtle differences between years in the types of resources used. Management of Gouldian finch populations will entail protection and management of the full range of grassland habitats used throughout the annual cycle, and will require predictive knowledge of the causes of patterning of seed resources and probably an ability to exert control over the timing and extent of fires in fire-prone seasonal savanna landscapes.

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Germination and establishment of the weeds Sida acuta and Pennisetum pedicellatum in the Northern Territory

Australian Journal of Experimental Agriculture ◽

10.1071/ea9800463 ◽

1980 ◽

Vol 20 (105) ◽

pp. 463 ◽

Cited By ~ 8

Author(s):

JJ Mott

Keyword(s):

Northern Territory ◽

Dry Season ◽

Dormant Seed ◽

Weed Species ◽

Wet Season ◽

Perennial Weed ◽

Hard Seed ◽

Sida Acuta ◽

Seed Fall ◽

Almost All

Two serious weed species in the Northern Territory are Sida acuta, a perennial weed of improved pastures, and Pennisetum pedicellatum, an annual grass that infests grain sorghum crops. In P. pedicellatum the customary successive ploughing carried out to kill seedlings in the early wet season may not give satisfactory control of the weed, while with S. acuta there appears to be a long-term dormant seed pool which can give rise to new generations of seedlings, Investigation into the germination requirements of the 2 species showed that both are dormant at seed fall and require high alternating temperatures to remove an after-ripening requirement. In addition S. acuta needs a further period at high temperature to fracture its impermeable seed coat. Almost all P. pedicellatum seed is non-dormant at the end of the dry season, but that of S. acuta still retains 30% hard seed after one dry season. In the field P. pedicellatum germinated faster than S. acuta, with 80% of the total wet season germination occurring with the first rain. In S. acuta germination was spread over the first 2 months of the season. Ploughing immediately after the break of the wet season killed seedlings of P. pedicellatum, but could bury viable dormant seed. Once buried, this store of dormant seed could remain viable and germinate when disturbed at crop planting. At the end of the wet season no viable seed of P. pedicellatum remained in the soil, but there could be a considerable amount of hard S. acuta seed. The results suggest that control of P. pedicellatum could be best accomplished by the use of minimum tillage procedures, with little ground disturbance to bury the seed, while oversowing with a vigorous perennial pasture species such as calopo (Calopognium mucunoides) could lead to suppression of S. acuta.

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Seasonal variations in the macroinvertebrate fauna of billabongs along Magela Creek, Northern Territory

Marine and Freshwater Research ◽

10.1071/mf9820329 ◽

1982 ◽

Vol 33 (2) ◽

pp. 329 ◽

Cited By ~ 27

Author(s):

R Marchant

Keyword(s):

Seasonal Variations ◽

Littoral Zone ◽

Northern Territory ◽

Dry Season ◽

Wet Season ◽

The Mean ◽

Macroinvertebrate Fauna

The littoral zone of five permanent billabongs along Magela Creek was sampled monthly over 1 year for macroinvertebrates. In three shallow billabongs, greatest numbers of taxa (about 45) and of individuals (about 1000 individuals per minute) were caught in the late wet season and early dry season (April-July); by the end of the dry season (December) these values had decreased to about 18 taxa and about 200 individuals per minute. Fluctuations were not so marked in two deep (or channel) billabongs: rarely were there fewer than 30 taxa and 400 individuals per minute present, and maximal values were similar to those in the shallow billabongs. These changes appeared to be associated with the growth of macrophytes, which occurred during the wet season in all billabongs. There was little variation between billabongs in the mean composition of the fauna.

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OCEANOGRAPHIC CHARACTERISTICS OF KLABAT BAY, BANGKA ISLAND, INDONESIA

Marine Research in Indonesia ◽

10.14203/mri.v32i2.437 ◽

1970 ◽

Vol 32 (2) ◽

pp. 49-54

Author(s):

Suhendar I. Sachoemar ◽

Agus Kristijono ◽

Tetsuo Yanagi

Keyword(s):

Chlorophyll A ◽

Inorganic Nitrogen ◽

Outer Part ◽

Total Suspended Solid ◽

Inorganic Phosphorus ◽

Suspended Solid ◽

Dry Season ◽

Wet Season ◽

High Precipitation ◽

Observation Results

The oceanographic characteristics of Klabat Bay in Bangka Island of Indonesia were investigated by using a series of temperature, salinity, turbidity, TSS (total suspended solid), transparency, DIN (Dissolved Inorganic Nitrogen), DIP (Dissolved Inorganic Phosphorus), DO (Dissolved Oxygen) and chlorophyll-a data in the wet season (Northwest Monsoon) and dry season (Southeast Monsoon) of 2003, respectively. The observation results show that the hydro-oceanographic characteristics of Klabat Bay in the inner part and the outer part of the bay were dominantly influenced by the terrestrial and oceanic environment, respectively. High precipitation during the wet season decreased salinity, DO and transparency and increased total suspended solid (TSS), turbidity, DIN and chlorophyll-a within the bay. The reverse occurred during the dry season, except DIP.

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Distribution and abundance of herons, egrets, ibises and spoonbills in the Alligator Rivers Region, Northern Territory

Wildlife Research ◽

10.1071/wr9930023 ◽

1993 ◽

Vol 20 (1) ◽

pp. 23 ◽

Cited By ~ 7

Author(s):

SR Morton ◽

KG Brennan ◽

MD Armstrong

Keyword(s):

Northern Territory ◽

Dry Season ◽

Correction Factors ◽

The South ◽

Wet Season ◽

Fresh Waters ◽

Aerial Surveys ◽

Sacred Ibis ◽

Egretta Garzetta

Aerial surveys between 1981 and 1984 were used to identify monthly trends in the abundance of Pacific herons (Ardea pacifica), pied herons (Ardea picata), cattle egrets (Ardeola ibis), great egrets (Egretta alba), little egrets (Egretta garzetta), intermediate egrets (Egretta intermedia), glossy ibis (Plegadis falcinellus), sacred ibis (Threskiornis aethiopica), straw-necked ibis (Threskiornis spinicollis) and royal spoonbills (Platalea regia) on five floodplains of the Alligator Rivers region, 250 km east of Darwin in the monsoonal Northern Territory. Ground surveys were conducted during the same period on one of the floodplains, the Magela. The aerial surveys indicated that the Magela floodplain was inhabited by few of these birds during the wet season (November-March), but that numbers then increased substantially in the dry season. The Nourlangie floodplain and Boggy Plain (a large backswamp of the South Alligator floodplain) showed similar patterns, but the numbers of birds tended to be lower. Birds were generally uncommon on the shallower East Alligator and Cooper floodplains, except for egrets in the wet season. Ground surveys suggested that the birds sought out the persistent swamps that characterise the Magela foodplain in the dry season. Ground surveys also indicated that aerial surveys underestimated densities. On the basis of correction factors calculated from ground surveys, peak numbers on the five floodplains were roughly estimated to be about 4000 pacific herons, 50 000 pied herons, 300 000 egrets (primarily intermediate egrets), 60 000 glossy ibis, 16 000 sacred ibis, 80 000 straw-necked ibis and 35 000 royal spoonbills. Great-billed herons (Ardea sumatrana), white-faced herons (Ardea novaehollandiae), striated herons (Butorides striata), rufous night herons (Nycticorax caledonicus), black bitterns (Dupetor flavicollis) and yellow-billed spoonbills (Platalea flavipes) were recorded sporadically in low numbers. The Alligator Rivers region acted as a dry-season refuge for herons, egrets, ibises and spoonbills because of the unusually persistent fresh waters of the Magela and Nourlangie floodplains and some of the backswamps of the South Alligator, such as Boggy Plain.

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