Cylinder Beach Field Report

Cylinder Beach is an extremely popular tourist destination that resides on North Stradbroke Island. Rated the most popular beach in Queensland in 2017 and the third most popular in 2021, the beach provides for an average of 300 000 visitors each year although COVID-19 may have reduced the number of international tourists in recent years. Councillor Peter Mitchell from Redland City Council commented in an email that 'Cylinder is a complex area with coastal processes, overland water flow, vegetation changes, human impacts, etc.' This should not be a reason for the Redland City Council to ignore the major issues faced by the island.

The focal point of this investigation is on the lagoon situated at Cylinder Beach. Here, various substances will be tested for their quantitative prominence on the 1st and 2nd of March, 2021. This in-situ data includes, nitrate and E. coli levels. Beach profiles, vegetation quadrats and animal specification will be conducted. Additionally, other primary data incited will be interviews and surveys undertaken by the public and workers such as lifeguards and shopkeepers on Stradbroke Island using Survey123. This will also allow for qualitative data to be recorded, furthering increasing the preciseness and accuracy of this report.

Secondary data was required to not only justify and support primary data collected but also provide previous data and visual footage regarding the water quality of the island using ArcGIS and the Wayback app. Allowing a comparison of multiple sets of data and various correlations to be proven or disproven, this conceited a new depth to the investigation. The report will include State of the Environment framework to search for a proposal to effectively analyse the issues of water quality and vegetation on North Stradbroke Island (Figure 2).

Shown in Figure 8, a lagoon had formed extremely close to the beach access point and surf lifesaving flags. Upon the analysis of several natural and anthropogenic changes, it is evident as to why the lagoon had formed and the implications that is presents.

It is evident that the lagoon undergoes temporal changes. According to Matt Burns, it is mainly present during summer and from 1955 to 2021 has experienced significant transformations.

Beach profiling at three sites was conducted. Two of these were at varying points where the lagoon was present (Figure 12 & 13) and a third where the lagoon was not present (Figure 14). The three sites tested have been mapped as shown in Figure 15. Profile 1 and 2 were investigated as there was either a lagoon present or wet and compact sand indicating a lagoon presence in high tide or times of high rainfall. The lagoon's prominence is graphically evident in Figure 12 and 13 as there is a significant segment of the profile with an angle of depression and then it continues back to an incline. Thus, the lagoon forms in this prominent depression in the profile which allows water to form a permanent lagoon.

The prominence of sandy soil septic systems led to the hypothesis that the water quality of the lagoon at Cylinder Beach may be affected. Samples of water temperature, pH, conductivity and E. coli were collected and analysed for their prevalence. The relevant implications of these results was also researched to deduce the environmental and social outcomes and a subsequent proposal.

There were 5 sites tested for the prevalence of E. coli. BioTech Laboratories, an air, food, water and environmental testing company was utilised to have the samples professionally analysed. Shown in Figure 15, Site 1 had the highest levels of E. coli with 1600 CFU/100mL being recorded. According to BioTech, samples 'should not exceed 40 Enterococci per 100mL.' Thus, with a reading 40 times over the safe bathing level, it is evident that an external factor is acting upon the lagoon for it to have reached these significantly elevated levels. Dick Coperman, a member of Friends of Stradbroke Island (FOSI), declared that,

As there are tourist areas situated directly above this 4WD access point and stated by Dick Copeman, are "old and non-sewered", qualitative data has proven that the presence of these sandy soil septic systems has directly impacted the water quality of the lagoon.

A newsletter composed by Friends of Stradbroke Island that investigates E. coli levels in 2018 corroborates this report. It highlights that the high E. coli levels is an ongoing issue and has been for the past 18 years.

With a CFU/100mL of 230, it is evident that Site 2 has also been impacted by the septic systems but on a lesser scale. Utilising the proximity buffer of 30m on each site, it is evident that Site 1, 3 and 5, all have a correlation. As Site 1 is a 4WD access point, tractors often drive onto the beach and then through Site 3 to unload and offload boats as fishing occurs off the Cylinder Beach shore. Thus cross contamination of these sites may occur as well as a transfer of E. coli. This is supported by Site 3's E. coli level of 580CFU/100mL which is 14.5 times more than the safe concentration of 40CFU/100mL. Moreover, shown in Figure 15 it is highlighted that Site 3 and Site 5 have a direct correlation. During high tide periods, the lagoon is flushed and exits directly into the ocean via Site 5 on the far Eastern side of the lagoon. Although the E. coli result is deemed a safe concentration of 7CFU/100mL, the sample was collected before the high tide cause the lagoon to flush out. This suggests that the results could have been higher if a sample was collected while this was occurring.

Figure 17 shows the lagoon refilling with salt water. This occurs once every four weeks thus highlighting that the lagoon is a mainly stagnant body of water that rarely replenishes with new salt water. This catalyses the exponential reproduction of E. coli.

It is known that the lagoon contains both fresh and salt water due to the conductivity of the water samples. According to Environment and Natural Resources (ENR), the conductivity of freshwater ranges from 0-200uS/cm and saltwater ranges from 1000-10 000uS/cm. The Sites with a neutral pH (Sites 3, 4, 5, and 6) were found to also have a higher conductivity all in the saltwater range of 1000-10 000uS/cm. On the other hand, Sites 1 and 2,--the sites closest to the septic leech fields with significant E. coli results (Figure 15)--have conductivities of approximately 400uS/cm. This infers a presence of both salt and fresh water due to the large distance between the high berm and these sites

According to e-Education institute, the optimal temperature range for the majority of algal species is 20-30 degrees Celsius (e-Education institute, 2021) . Moreover, Site 2 and 3 have a temperature of approximately 26 degrees Celsius and thus algae growth in these sites is optimised. Theses living conditions allow the algae to grow at an exponential rate. These factors lead to the eutrophication of the lagoon. When this algae dies and decomposes, carbon dioxide concentrations in the bracken water increases which thus decreases the pH of the water, making it acidic. This is why both Sites 1 and 2 are acidic.

Figure 18 and 19 highlights the eutrophication of the lagoon. Not only does the decomposition of algae decrease the pH of the water, it also acts as nutrients for the surrounding soil.

Shown above is the back dune (Figure 20) and front dune (Figure 21) of Cylinder beach. Figure 20 highlights the mature vegetation with melaleuca, she-oak, sedges, cotton trees, pigface and low-lying ferns. The front dune mainly consists of sedges (Figure 21) as it is deemed a prolific seeder and thrives in low oxygen environments--which are present in Site 1 and 2--with extremely moist soil and can adapt very quickly to the surrounding conditions (Prendusi, T, 2020). During secondary succession, algae which is a pioneer species is followed by grasses and perennials and acts as nutrients for these species.

Due to the presence of the lagoon and the subsequent amplified nutrient levels, the back dune vegetation is slowly advancing down the beach. This is shown by Figure 23 as there are young she-oak trees present amongst the sedges on the foredune.

According to the Queensland Government, Moreton Bay "contains some of Australia's most significant wetlands." Sections of the bay as shown in Figure 24 are classified as Ramsar sites and under the Ramsar convention is considered of "international importance" (Queensland Wetlands Program, 2013). These Ramsar sites hold a significant amount of biodiversity and as one of Australia's largest shorebird habitats, provides for "28 species of migratory shorebirds comprising over 30,000 individuals" (Queensland Wetlands Program, 2013). Moreover, Olearia hygrophila, the endangered swamp daisy, is specific to Stradbroke Island wetlands.

Therefore, if the lagoon on Cylinder Beach was left to secondary succession, another Ramsar site could be created to accommodate for various migratory birds and endangered species. According to the Queensland Government, sedges are commonly found in wetlands and, if that natural progression and transformation of the land was left untouched, other plants that are currently found in the back dunes will begin to proliferate in this new wetland. These include various species of she-oak, rush, swamp daisy, sedge, and grass.

Highlighted by Figure 13, Beach profile site 3 will not develop a lagoon. Thus, tourists will still be able to use the beach and provide businesses in the area with income.

According to the surveys collected, Cylinder Beach is the most popular beach on the island (Figure 26). Thus, it is crucial that Site 3 of the beach profiling--where the surf lifesaving flags were situated--is properly maintained for beach visitors to continue utilising the beach. Shown in Figure 16, as Site 5 had levels of E. coli less than 10CFU/100mL, it can be deduced that it will still be safe for people to swim in the ocean.

Conclusion

Cylinder Beach has experienced numerous anthropogenic and natural transformations. As a significantly popular tourist destination, the land cover transformations of the beach have a large impact on not only the beachgoers of the Island but also the animals and plants that reside there. Using the State of the Environment framework, an effective proposal was suggested to develop a maintained wetland on the beach. This framework was also used to analyse the risks associated with the prolonged residential sewerage of Area 3 and 4 in Point Lookout as well as the overall water quality of the lagoon developed on the beach.