Exotic fish impacts on lake community structure and function in Western Victoria, Australia
- Authors: Khan, Tariq
- Date: 2002
- Type: Text , Thesis , PhD
- Full Text:
- Description: The researcher investigated a number of closed catchment lakes in western Victoria that have been stocked with exotic fish. Exotic-native fish interactions were studied and the potential of the exotic species to affect the lake ecosystem structure was explored.
- Description: Doctor of Philosophy
Dietary studies on exotic carp (Cyprinus carpio L.) from two lakes of western Victoria, Australia
- Authors: Khan, Tariq
- Date: 2003
- Type: Text , Journal article
- Relation: Aquatic Sciences Vol. 65, no. 3 (2003), p. 272-286
- Full Text: false
- Reviewed:
- Description: There is little published information on the impacts of exotic fishes in the shallow slightly saline, closed catchment lakes of western Victoria. The present study assessed the diet of exotic carp (Cyprinus carpio) from two lakes of western Victoria (Lake Colac and Lake Modewarre) between November 1999-September 2001, using a numerical and volumetric method of gut contents analysis. Carp larvae <2 cm total length fed exclusively on microcrustacea (Cladocera and Copepoda). At a mean total length of >2 cm carp larvae shifted their diet to include benthic food resources, but microcrustacea still dominated the larval diet. Small carp (≤15 cm) showed a high preference for microcrustacea and tended to avoid benthic macroinvertebrate food resources. As carp size increased the proportion of macroinvertebrates in gut contents increased. Medium (15-40 cm) and large sized carp (>40 cm) displayed broad food assemblages in their guts with microcrustacea, Gastropoda, Ostracoda, Amphipoda and detritus being dominant. Carp showed a selective preference for Diptera and a balanced preference for Amphipoda. Schoener's dietary overlap was high between small and medium carp (0.55-0.65) and medium and large carp (0.72-0.74) but was low between small and large carp (0.36-0.44). When considering only benthic macroinvertebrate food resources, Hurlbert's dietary overlap between size classes of carp remained reasonably low. There were no observable seasonal patterns in the diet of carp in the two lakes but the proportion of the food items in the gut varied between sampling occasions. This study identified the potential of exotic carp in altering lake function by feeding predominantly on microcrustacea, thus causing a 'top-down' trophic cascade.
- Description: C1
- Description: 2003000549
Evidence for invasive carp mediated trophic cascade in shallow lakes of western Victoria, Australia
- Authors: Khan, Tariq , Wilson, Michael , Khan, Minal
- Date: 2003
- Type: Text , Journal article
- Relation: Hydrobiologia Vol. 506-509, no. (2003), p. 465-472
- Full Text: false
- Reviewed:
- Description: Lakes of western Victoria are typically shallow (2-3 m), slightly saline (3-8 ppt) and eutrophic (total phosphorus 0.1-5 mg l-1 and total nitrogen 3-8 mg l-1). These lakes are prone to algal blooms in late spring and summer. We conducted experiments in ponds to determine whether lake zooplankton exert enough grazing pressure to control algal blooms and also if carp predation can regulate zooplankton communities and increase algal biomass. Zooplankton grazing (high zooplankton, low zooplankton and control) and carp predation (carp, nutrient and control) experiments had three treatments and each treatment had three replicates. Algal numbers and biomass (28
- Description: C1
- Description: 2003000543
Limnology of four saline lakes in western Victoria, Australia : I. Physico-chemical parameters
- Authors: Khan, Tariq
- Date: 2003
- Type: Text , Journal article
- Relation: Limnologica Vol. 33, no. 4 (2003), p. 316-326
- Full Text: false
- Reviewed:
- Description: Major physico-chemical parameters of four saline lakes (Lake Colac, Modewarre, Bolac and Tooliorook), in the volcanic plains of western Victoria (Australia), recorded bi-monthly between November 1999-September 2001 are described. Lakes are permanent, large (surface area range 3.5-29.6 km2) and shallow (mean depth range 1.5-3.9 m). Physico-chemical parameters revealed that lakes were homogenous with few differences between sites within lakes. Of the four lakes, Lake Modewarre had the highest salinity of 8 ppt with weak seasonal fluctuations in salinity in all the lakes. All the lakes were turbid (turbidity range 30-659 NTU), with low light penetration (suspended solids range 23-465 mg 1-1) and low Secchi depth (Secchi depth range 7.7-89 cm). pH of the lakes varied between 8.2-9.3 with low seasonal variations, indicating well buffered waters. Based on nutrient status, lakes were classified as eutrophic to highly eutrophic with higher nutrient concentrations. Nitrogen was limiting in one lake (Lake Colac) and phosphorus in the other three lakes. Meteorological events probably influence the physico-chemical parameters of these lakes strongly.
- Description: C1
- Description: 2003000635
Limnology of four saline lakes in western Victoria, Australia : II. Biological parameters
- Authors: Khan, Tariq
- Date: 2003
- Type: Text , Journal article
- Relation: Limnologica Vol. 33, no. 4 (2003), p. 327-339
- Full Text: false
- Reviewed:
- Description: Major biological parameters of four permanent (Lake Colac, Modewarre, Bolac and Tooliorook), shallow and slightly saline lakes in the volcanic plains of western Victoria, Australia recorded bi-monthly between November 1999-September 2001 are described. Chlorophyll a concentration ranged from 3-29
- Description: C1
- Description: 2003000634
Habitat use and movement of river blackfish (Gadopsis marmoratus R.) in a highly modified Victorian stream, Australia
- Authors: Khan, Minal , Khan, Tariq , Wilson, Michael
- Date: 2004
- Type: Text , Journal article
- Relation: Ecology of Freshwater Fish Vol. 13, no. 4 (2004), p. 285-293
- Full Text: false
- Reviewed:
- Description: Movement and habitat use of river blackfish (Gadopsis marmoratus R.) was studied in a highly modified central Victorian stream (Birch Creek), Australia, using radio telemetry (N = 10) and mark-recapture (N = 113) between October 2001 to May 2002, and November to December 2002 respectively. Blackfish had a small home range of 10-26 m with strong affinity to a pool. However, small movements within a pool were common which resulted in relatively large cumulative movements. At a diel scale there were no significant differences in blackfish movement between day and night (Kruskal-Wallis test, P = 0.95). Six of seven blackfish translocated 40 m upstream or downstream of their original positions returned within 48 h, suggesting strong affinity not only to a pool, but also to a small region within a pool. Blackfish utilised slow flowing (0-20 cm. s-1) and deep waters (40-60 cm). Blackfish were strongly associated with the instream cover habitats of undercut banks and boulders. Significant differences were recorded in instream cover and water velocity used by blackfish between day and night (Kruskal-Wallis test, P = <0.01). At night blackfish used open areas with high water velocities whereas during the day blackfish used complex undercut banks with low water velocities. © Blackwell Munksgaard, 2004.
- Description: C1
- Description: 2003000779
Risk factors associated with gallstone disease in women
- Authors: Paracha, Parvez , Asif, Yasmin , Vriesekoop, Frank , Ullah, Shahid , Abbas, Muhammad , Paracha, Saima , Khan, Tariq
- Date: 2012
- Type: Text , Journal article
- Relation: e-SPEN Journal Vol. 7, no. 3 (2012), p. e129-e134
- Full Text: false
- Reviewed:
- Description: Background & aims: Gallstone disease in middle-aged women has been increasing due to changing dietary and environmental factors varying from country to country. The aim of the study was to determine the risk factors associated with gallstone disease in women aged ≥35 years of the district of Peshawar, Pakistan. Study design: A hospital-based case-control study. Methods: One hundred and ten women (55 cases and 55 controls) attending the Surgical Departments of two Government hospitals were enrolled for the study. All subjects were screened for ultra-sonography; biochemical and anthropometric measurements. They were interviewed for their past medical history; physical activity; 24-hr dietary recall and for demographic and socio-economic characteristics. Data were analyzed using Student's t-test, chi-square and multivariate conditional logistic regression to determine mean differences between the continuous variables; establish association between the categorical variables and to determine risk factors associated with gallstone disease, respectively. Results: Of 55 cases, 15 (27%) had a family history of gallstone disease. Thirty five percent of the cases had a single calculus while 65% had multiple calculi with mean size of 14.85 ± 14.46 mm. Conditional logistic regression analysis demonstrated that the body mass index was the most significant risk factor for women's gallstone disease. The adjusted odds ratio for women's BMI ≥ 25 kg/m 2 was 2.93 (95% CI: 1.43-6.01), indicating almost a three times higher risk of gallstone disease than women with BMI < 25 kg/m 2. The risk of gallstone disease was higher for women with low vitamin C intake (OR = 0.27; 95% CI: 0.08-0.91) and low physical activity (OR = 0.48; 95% CI: 0.24-0.96) than women with more physically active (score > 1.3) and having dietary vitamin C intake ≥ 75 mg per day. Conclusion: High body mass index, physical inactivity and low vitamin C intake are associated with gallstone disease in Pakistani women. Longitudinal studies are needed to confirm these findings. © 2012 European Society for Clinical Nutrition and Metabolism.