Weston J. LaGrandeur), is an endemic species to Australia that spends - PDF document

Weston J. LaGrandeur), is an endemic species to Australia that spends all of its life in and around riverine areas. This study compared physical characteristics of four different sites (two undisturbed, two disturbed less than one year ago) located on Ri�e Creek in Far North Queensland. The site with more platypus sightings was grazed by cattle until January 2011. The two previously disturbed sites had a higher average velocity, bank angle closer to ninety degrees, taller bank heights and depths selects foraging and living sites based upon characteristics such as Ornithorhynchus anatinus has a long list of unique physiological characteristics including the electromagnetic sensitivity in its bill, a poisonous barb and its egg laying NATURAL SCIENCES 5:45 to 6:45 AM and 5:00 to 6:00 PM on October 14, 2011 through to the morning of the 17th. The �rst morning observation on October 15, 2011 was taken from 5:30 to 6:30 AM but was adjusted to the later time due to the lack of visibility for the �rst 15 minutes. Observers noted when the platypuses emerged and, if possible, how long the platypuses were at the surface, taking note of dive time. All four sites were observed at the same time. In total, the research team tallied 24 hours of At each of the four sites, river 12.5 m and 25 m marks along the transect. The sediments were collected in a plastic river along the respective distances of the transect. The river sediments were separated using a metric scale. Then, the sediment was sifted using a 2 mm sieve. Gravel (>2 mm) was then weighed and put back into the sample jar. The remaining sediment was sifted in a 1 mm sieve. Sand (.5-1 mm) was weighed and set aside. Finally, the last of the sediment was determined to be sediment (.5-.25 mm) or �ne sediment () separated grains whereas �ne sediment is not grainy to the touch and has no visible grains. The weights were averaged among the average. Bank sediments were collected current water level. The bank sediments were grouped holistically using color, texture and general soil composition as the using a clinometer at water level. These measurements were taken at the three sites on both sides of the river. The angles were then averaged for each respective side of the river. If a bank measured greater than 45°, the bank height was recorded using a transect measuring tape. The measurement at which the riverbank angle tapered to less The maximum and minimum widths of the creeks were measured using a transect tape stretched across the widest respectively. Maximum depth of the creeks at each of the four sites was also measured using a transect tape. Maximum velocity was measured in the area of the river with the most visibly strong current. Maps were trees, erosion and amount pooled taken into account. To assess the quantity of submerged logs, a member of the research team walked perpendicular to the 12.5 m mark on the transect across the river while upon. Foliage Projective Cover (FPC) was measured every 5 meters along a transect set perpendicular to the 12.5 m mark on the original transect. The percentages were then averaged for each site. Tree girth was measured using a tailor’s tape along this same perpendicular transect for trees that were taller than 2 m. Again, the values were averaged to obtain a representative Maps of the four individual sites: Sheoak A (Fig. 2), Sheoak B (Fig. 3), Wetherby A (Fig. 4) and Wetherby B (Fig. 5) give a visual interpretation of the stream and bank morphology. Sheoak A and Sheoak B are dominated by pool regions which explains the slow currents through the transect site. Wetherby A and B show more signs of erosion than the sites at Sheoak. Wetherby B has many more fallen logs that are visible from the bank, whereas Wetherby A and Sheoak A have major parts of the banks Prior to riparian fencing, the Wetherby sites were not fenced off to keep out cattle. Cattle were allowed to walk down and into Ri�e creek causing bank erosion as well as decreased water quality with bovine waste. In January 2011, riparian fencing was placed along the Wetherby portions of Ri�e Creek, which led to 100% cattle exclusion. However, the fencing does not keep feral animals such as pigs and cats out of the area. Furthermore, upstream from the Wetherby sites, Bushy creek joins with Ri�e Creek which increases catchment input. The water level can rise up to four There is much dissimilarity across the river metamorphic data; however, differences in maximum velocity, maximum width and average bank angle factor heavily into the variations between Sheoak and Wetherby. The maximum velocities for Wetherby A and Wetherby B are 5 and 16 times faster than the �ow rates in Sheoak, respectively. Similarly, the maximum widths of Wetherby A and B are larger by 2.2 and 1.5 times compared to the Sheoak sites. The minimum widths, however, differ from site to site with Wetherby A and Sheoak B sharing the largest minimum width. Wetherby B is an outlier in the average tree girth with a measurement nearly 30 cm larger than the next closest. This is, in part, due to several large gum trees located within the transect. Wetherby A and B both possess a bank with at least a 60°average bank angle whereas Sheoak B only contains one bank that is barely greater than 45°. The tallest average A had no bank heights because there were no banks with an angle of greater than 45°. A satellite image of the four sites. The Wetherby sites are surrounded by cattle pasture and sugarcane �elds. The Sheoak sites are surrounded by thicker, undisturbed riparian vegetation with sugar cane paddocks adjacent to the river. The Wetherby A measurements came from the far side of the creek, whereas Wetherby B and Sheoak B had taller banks on the trail side. No glaring disparities appear with the rest of the shared data, although attention should be drawn to the FPC in Sheoak. ecosystem through which Ri�e Creek River sediment analysis shows sediments in Wetherby compared to the sediments in Sheoak. Both Wetherby sites whereas the Sheoak sites have less than Individually, Wetherby A has nearly an equal amount of sand and gravel, whereas Wetherby B contained 9% more sand than gravel. Wetherby A also has sediment contrasting the �ne sediment that exists in Wetherby B. Moreover, sediment and �ne sediment dominate the creek composites at the Sheoak sites with 70% at Sheoak A and Sheoak B respectively. Sheoak A has only sediment with a nearly equal mixture of sand and gravel, whereas Sheoak B contains �ne sediment with more gravel than sand. Organic matter only appears in the Wetherby A sediments. Unaccounted sediment refers to the sediment lost during the sifting process. This percentage (by sediment sticking in the sieves. These percentages, however, do not drastically sediments at each site shows three dominant soil types: sedimentary, sand, and clay. Wetherby B has the one exception with a bank full of a unique condensation of sedimentary soil into stalactite type remain consistent with the river sediments. Wetherby A and B have dark brown sand. However, the sand is darker and much more condensed than the sand sampled in the actual river bed. Sheoak B is all chocolate-brown clay-type soil that is homogenous and looks very similar to the �ne sediment found in the creek bed. Sheoak A contains light tan soil with �ne sedimentary particles that clumps together. This site also contains Wetherby sites except a lighter color. All previously collected results ultimately factor into the amount of platypus sightings. No sightings were recorded period. There were also no sightings at any site in the evenings of October 14. However, Wetherby A had the most individual sightings of platypuses with morning observations totaling 9 sightings. Wetherby A had a 100% sighting rate in the morning observation periods. Wetherby B Sheoak A had 4 total sightings, but was the The average time at the surface varied from site to site and from day to day. However, Wetherby B had much shorter average times when compared to the averages of Wetherby A and Sheoak A.of factors determining habitat structure. Stream sediment analysis showed a large difference between the compositions of the streambeds at Wetherby and Sheoak (Fig. correlating platypus presence to stream However, these studies contain an evident contradiction. Some studies found that �ne stream sediments, such as silt, encourage platypus inhabitance, that stream sediments composed mainly of gravel and larger particles attract platypus The data collected in this study supports the latter research. The two Wetherby sites had much more gravel and sand, whereas the Sheoak sites were dominated by sediment and �ne sediment. It is possible that platypuses prefer the larger substrate for several reasons. The presence of macroinvertebrates in one substrate more than the other could suggest why platypuses were spotted more at Wetherby. slow currentsteep, eroded bankCollapsed, highly erodedSteepMany tree rootsMore gradual inclineMany tree roots Very steep bankCollapsed, highly eroded SHEOAK B = Log= Tree on creek bank = area of sand incursion into creekPlatypus BurrowProminent roots in creek and on - Gradual Slope- No signs of erosion- Leaf litter covers most of bankSHEOAK A- Bank similar to 0-12.5m min width - Drastic slope covered with many branches and roots- Completely covered with roots Fallen LogSlow Current85% pool area - Roots entering water- Trail down to river is only sign of erosion = Tree on bank= Fallen Log Fig. 2 Sheoak A Fig. 3 Sheoak B Coarse substrates such as gravel and sand provide more surface area for invertebrates to inhabit as well as a more stable substrate However, a concurrent study focused on invertebrate diversity and abundance indicated that both invertebrate abundance and diversity was higher in data). Another study done in New South Wales supports the current �ndings that there is greater invertebrate abundance in the �ner sediment areas of platypus Milione invertebrate diversity is not as important as abundance due to the adaptable diet of The many contradictions with concern to correlating platypus presence to invertebrate abundance leads to a possible conclusion: the platypuses at Wetherby inhabited that speci�c area for reasons other than invertebrate abundance and diversity. The greater presence of invertebrates at Wetherby further suggests that as long as there is suf�cient food, factors such as average �ow rate, river depth and bank morphometrics factor into The differences between Wetherby and Sheoak concerning average stream velocity suggest that this is a physical factor that platypuses detect when inhabiting and foraging in certain sites (Table 1). Platypuses tend to avoid fast �owing streams and sites with large rif�e areas due to the large energy expenditure required to hunt in such areas. However, stagnation and strati�cation decrease the concentrations of dissolved oxygen and increase nutrient concentrations which further increase the risk of toxic algal blooms’ negative impacts on aquatic invertebrate and �sh communities. Ri�e Creek at Wetherby had a stronger �ow rate due to the input of Bushy Creek upstream of the observation sites. More sightings at the Wetherby show that the rif�e areas in the Wetherby sites were not too strong to completely discourage platypus foraging. Also, as seen in the site pro�les, Wetherby has pooled areas which suggest that an area with enough current to create a more gravel/sand dominated substrate along with pooled area provides an ideal foraging habitat for platypuses. The �ow rate at Sheoak B was slow enough to show evidence of stagnancy (Table 1). Platypuses were not seen at all at here, possibly due to the stagnancy of the pool which had a �lm that formed over the Maximum stream depth did not vary much across the four sites. However, the Wetherby sites did have deeper maximum depths than those of Sheoak. 98% of platypus dives were in waters less than three meters, with the average dive being 1.28 meters. All sites have maximum depths less than three meters and greater than 1 meter. The larger maximum depths at Wetherby could suggest that platypuses prefer pool depths of greater than 1.5 important to the platypus because this is where burrows are made. Platypuses use activities, but are also used for mating and egg laying. Stream bank morphometrics present more differences in terms of bank angle and bank height between Wetherby and Sheoak. The Wetherby sites have at least one bank each with an average angle greater than 60 degrees. Serena et al.showed that a positive correlation existed Although the Wetherby banks are not vertical, they have an angle closer to 90° than the Sheoak sites. Platypus presence is evidence of a burrow as close activity is spent in a 100 meter range of the nearest burrow.No burrows were observed at any of burrows are often underwater or hidden site with no platypus observations. Yet, it was the only site with visible platypus burrows, indicating that bank height and soil composition can be seen as an example of where the platypus actually dig burrows. The sites with platypus observations or greater. However, there is no evident pattern concerning stream bank sediments = Tree on bank= Fallen Log Bank is steep and eroded. A lot of roots from above trees touching the water surface very steep,eroded banksteep, eroded bank up until 0m(0-25m): Very gradual bank slope, a lot of fallen trees on shore. Less dramaatic signs of erosion.medium/slow current WETHERBY B slow current;pool regionvery shallow grade; deep sand; no signicant exposed roots but several large river gum trees 0m12.5m 25m steep grade; sedimented soil; may exposed tree roots; highly erodedstrong currentwater ow area of high root density or fallen branchesWETHERBY A tree on creek Wetherby AWetherby B requires a certain angle and height as opposed to a certain sediment composition. A very similar study to this research was conducted in October of 2010 using the same sites at both Wetherby Station and Sheoak Ridge. However, several differences between the data from a year ago and these data exist. While the of the Wetherby sites, there was 100% AM sightings at Wetherby A and 50% AM sightings at Wetherby B in this year’s study et al. unpublished data). These differences could be attributed to the riparian fencing constructed in January 2011 along the Wetherby sites which keeps cattle out of the portion of Ri�e Creek that was studied. A year ago, the creek was observed to be heavily impacted by cattle mainly with concern to water quality and heavy bank erosion. The unrestricted grazing of cattle vegetation, erosion and catchment �lling.Riparian vegetation is important due to its two-fold effect on both burrows and water quality. The riparian fencing has already shown a direct impact within eight months of its construction. Eliminating disturbance allowed for platypuses to move back into the Wetherby sites. There is no way of speculating whether these are the same platypuses observed in the Sheoak sites last year, but the presence of more platypuses in the Wetherby sites suggests that it is a more physically suitable environment for The contradictions in trends between platypus presence and macroinvertebrate abundance suggest that the platypus is more perceptive of physical differences within its habitat. These differences include an ideal velocity, bank angles close to vertical, creek depths between 1 and 3 meters and bank heights around 1.85 meters or greater. Furthermore, riparian fencing installed along Ri�e Creek located in the Wetherby sites in January 2011 highlights the differences between this year’s study and the study done prior to the fencing. More platypus sightings at Wetherby and the noted changes in stream physiology suggest that Wetherby is a The protection of platypuses are important because not only are they a unique cultural marker of Australia, they play an integral role in stream ecosystems. Given the platypus’ ability to adapt and its resilience, it can be a good indicator of positive trends in habitat conservation and rehabilitation because it will be one of the �rst species to move back into a previously destroyed habitat. Furthermore, the success of the site rehabilitation at Wetherby is a good example of successful conservation efforts and can be used as encouragement for other land owners interested in conservation. The more knowledge gained about platypus habitat, the better the conservationist can manage and prepare reacting to the issues as they come. The conclusions of this paper offer a possible solution to the river sediment contention. However, it would be helpful for a study one site with its substrate majority being substrate majority. Also, a study devised to ascertain the minimum amount of food necessary for platypus foraging to occur could be useful for reintroduction efforts. Creating a yearly study at the Sheoak and Wetherby sites would be an invaluable asset to the topic of platypus research because such a longitudinal study does not exist. Certainly, continued environmental research into the platypuses’ habitat and health of this fascinating and iconic species. Although just a small piece of the puzzle, this research brings light upon how a platypus chooses its environment to inhabit. The more knowledge gained about the platypus, the better able ecologists will be to conserve one of the world’s most Wetherby AWetherby BSheoak AMax Width (m)Min Width (m)Avg. Velocity (m/s)# Submerged LogsAvg. Tree Girth at 12.5 Avg. Bank Angle: Trail Avg. Bank Angle: Far A side by side comparison of all sites to illustrate differences in river sediment composition. Three samples were taken at each site along the transect in the middle Table 1 Weston LaGrandeurin History at Stanford. Weston enjoys playing rugby for Stanford, working at Once he graduates, Weston plans on taking a year off to travel and work as an EMT before he goes to Medical School where he hopes to become 14.X.2011 15.X.2011 15.X.2011 16.X.2011 17.X.2011 Wetherby AAverage Time at surWetherby BAverage Time at surAverage Time at sur NA Average Time at surSpecial thanks to: Mr. John and Kathy Colless, Dr. Claire Baker, Kristen Malinak, Ana Guerra, Tess Morgridge, and Mr. Bill Anderegg.Goulburn River, Victoria.Zoology,1995;2. Gardner JL and Serena M. Spatial (Monotremata: Ornithorhynchidae). Australian Journal of Zoology, 1995; 43(1): 91-103.3. Grant TR, Temple-Smith PD. Field biology of perspectives. Philosophical Transactions of the 4. Serena M, Thomas JL et al. Use of environment. Aust J Zool, 1998;5. Manger P, Pettigrew J. Electroreception Mammalia).Philosophical Transactions: 6. Grant TR, Temple-Smith PD. Conservation Threats and Challenges, Aquatic Ecosystem 7. Klamt M, Thompson R et al. Early response Change Biology, 2011; 17(10): 3011-3018.Australian Wet Tropics catchment, north-Australian Mammalogy, 9. Serena M, Worley M et al. Effect of food platypus (O. anatinus) foraging activity. ZoolW, 2001;10. McLachlan-Troup TA, Dickman CR et al. Journal of Zoology, 11. Hawkins M, Battaglia A. Breeding behaviour of the platypus (O. anatinus) in captivity.Table 2 Platypus sightings by number of time surfaced. Times at surface averaged to obtain value in table. No sightings were recorded at 16.X.2011 NATURAL SCIENCES