Pondalowie Nearshore Marine Biounit
2016 Aquatic Ecosystem Condition Report
On the map, zoom in and click on the dots to view underwater video at each site
- Seagrass habitats throughout the biounit were variable.
- Condition of rocky reef communities also varied between sites.
About the Biounit
The Pondalowie biounit extends from Corny Point, south to the southwest tip of Yorke Peninsula at West Cape. The biounit faces to the west and receives high wave energies from the southern ocean. There are no significant creeks that flow to the marine environment in this biounit.
A large portion of the adjacent land is made up of Innes National Park, with the remaining adjacent land made up of dryland agriculture, but as there are no creeks in the biounit, runoff is likely to be negligible. There is a small shack community at Pondalowie Bay and a number of camp grounds used heavily during holiday periods. These use septic tanks or long drop toilets within the sand dunes that introduce pollutants into the groundwater, which flows to the coast.
An investigation of potential threats to water quality for the biounit predicted that Pondalowie was likely to be in Excellent condition. Pondalowie was not monitored in 2010.
A total of 3 sites were monitored during autumn 2016 to assess the condition of the biounit; 30% of the habitats were seagrass, while 34% were rocky reef with bare sand making up the remainder.
The southern end of the biounit was dominated by seagrasses, while in the north, seagrass was patchy often found growing between outcrops of reef.
The biounit was in Fair condition, which is lower than the predicted condition of Excellent.
This AECR assessed the condition of habitats in waters between 2–15 m deep throughout the Pondalowie biounit sampled in autumn 2016. There are large areas within the biounit that are deeper than 15 m which are not included as a part of this evaluation.
The results showed that habitats in the biounit were fair condition, variable and patchy. Pondalowie is influenced by occasional high wave energies, which is likely to affect habitats in a similar way to disturbance. As a result, there is considerable uncertainty in this assessment as to whether the condition that was observed is related to impacts from human actions or from natural environmental conditions.
Pondalowie Bay (m0139) supported the majority of the biounits seagrass with dense meadows of Amphibolis spp. and patchy Posidonia spp. Epiphyte cover low suggesting minimal nutrient input into the biounit at the time of sampling.
The reef system at Formby Bay (m0137) consisted of more than 50% robust brown canopy algae (Cystophora spp.) suggesting a healthy reef system. However Browns Beach (m0138) was the opposite with turfing algae dominating the reef and low abundances of robust brown algae and numerous urchins (Heliocidaris erythrogramma).
Nutrient concentrations were consistent throughout the biounit, although turbidity was more variable within Pondalowie Bay (m0139) which is likely related to the higher wave energy in this bay.
This biounit was not monitored in 2010, so it is unknown if the variability within between habitats is natural or if parts of the biounit are under stress from human use.
These findings suggest that the nearshore marine habitats are in fair condition.
Pressures and management responses
High visitor numbers in summer will increase pressure on existing septic and long drop toilet systems. These systems introduce pollutants into groundwater which is likely to flow to the coast.
Due to a steady increase in numbers of people camping in designated areas along the coast, the Yorke Peninsula Council has responded by installing new ecosystems toilets at 3 locations, Berry Bay, Gleesons and Daly Heads. These locations are regularly desludged and the effluent is disposed of in soakage trenches that are located greater than 100 meters from the high water mark in accordance with South Australian Health Commission requirements. Council, through their Bush Camping Working Party are hoping to install additional facilities as budgeted finances become available.
- Methods report for the nearshore marine ecosystems monitoring, evaluation and reporting program.