Douglas Nearshore Marine Biounit
2019 Aquatic Ecosystem Condition Report

The Douglas Biounit is broadly separated into 2 distinct parts, outside of Point Longnose is typified by dense and continuous Posidonia seagrass and some reef habitat. The region is well flushed and generally the sites are in good condition and have remained largely unchanged since the 2014 survey.

Inside of Point Longnose are a series of smaller bays connected by deeper channels, where habitats are a complex mixture of different species. Sites inside Point Longnose generally are in poor to very poor condition and many have degraded further since 2014. There is widespread loss of seagrass throughout the region but particularly at sites around Rabbit Island including m0400 (West Rabbit Is.), which went from Fair condition in 2010 but has degraded to be very poor in 2019. Similarly, sites within Mount Dutton Bay including m0407 (West Dutton Bay), which were considered Fair in 2014 declined to Very Poor in 2019. This degradation appears to be driven by nutrient enrichment, supported by numerous indicators such as the phytoplankton communities, abundant jellyfish, high numbers of small ascidians, bacterial mats, dense epiphytes and opportunistic algae. Many of the inner bays are poorly flushed, meaning any nutrient inputs are retained where they can degrade habitats.

The score classifies sites on the ecological condition based on habitat integrity outlined in the methods report. This score does not reflect suitability of the sites for other purposes including aquaculture production.

The condition of habitats in waters between 2–15 m deep throughout the Douglas biounit was assessed based on monitoring data collected during autumn 2019. There are some areas within the biounit that are deeper than 15 m which are not included as a part of this assessment. The score classifies sites on the ecological condition based on habitat integrity outlined in the methods report. This score does not reflect suitability of the sites for other purposes including aquaculture production.

Site	2019
	Condition	Trend
m0400, West Rabbit Is.	Very Poor
m0401, Farm Beach	Very Good
m0402, North Brothers	Fair
m0403, Kellidie Bay	Very Poor
m0404, East Rabbit Is.	Very Poor
m0407, West Dutton Bay	Very Poor
m0408, West Coffin Bay	Very Poor
m0409, Bulldog Pt.	Very Poor
m0411, Outside Longnose	Very Good
m0412, Pt. Sir Isaac	Very Good
m0413, Outside Coffin Bay	Good
m0416, Drummond Point	Excellent

The habitats outside of Point Longnose were dominated by extensive dense meadows of Posidonia spp. with most sites unchanged from 2014. However, m0413 outside Coffin Bay, showed a decline in seagrass cover. The seagrasses outside of Point Longnose were sparsely covered in epiphytes (if at all), and the composition of the phytoplankton communities (using the Fp ratio and size classes) suggest a low nutrient environment.

Point Drummond (m0416) is a complex rocky reef dominated by large robust brown algae (including Ecklonia radiata and Cystophora spp.) with dense and diverse red algal communities. This site is exposed to ocean swells and is very well flushed and found to be in excellent condition, consistent with 2014. Other positive signs of habitat condition are the numerous Blue Throated Wrasse (Notalabrus tetricus) and Blue Groper (Archoerodus gouldii) that were observed during the 2019 survey.

The findings in 2014 indicated that sites inside of Point Longnose were severely affected by nutrient enrichment, evidenced by the dense epiphytic algae on any seagrass, benthic microbial mats, abundant jellyfish and asicidans in places, and elevated phytoplankton (see 2014 reports here). In 2019, the condition of the habitats has declined further. Sites that previously had moderate amounts of mixed seagrass communities (eg: m0400, m0404 and m0407) had generally lost seagrass, taken over by the green algae Caulerpa spp. with any remaining seagrass blanketed in epiphytes. The phytoplankton communities showed elevated chlorophyll and were typical of mesotrophic environments. Generally, the condition of the sites inside Coffin Bay, and particularly inside Mount Dutton Bay and Kellidie Bays had declined to be scored as very poor, the worse score on the scale.

This region is commonly affected by upwellings which transport cool nutrient rich water from the continental shelf into coastal waters during autumn which greatly contribute to the regional productivity, but can also result in algal blooms. Recent evidence suggests that the upwellings are unlikely to be impacting the inner parts of Coffin Bay, but these areas are poorly flushed with residence times of between 80-100 days in parts^[1]. Any nutrients entering the system are likely to be retained in the system where they can impact on habitat condition.

There is overwhelming evidence to suggest that a number of sites inside Point Longnose are being affected by excess nutrients (eutrophication). This program has now observed that the composition of many of these sites has changed over relatively short period of time indicating that the system is out of balance and further degradation is likely unless substantial changes to the nutrient inputs occur.

^[1] Kaempf & Ellis 2015. 'Hydrodynamics and flushing of Coffin Bay, South Australia: A small tidal inverse estuary of interconnected bays'. J Coast. Res. 31(2), 447-456

Pressures	Management responses
Agricultural runoff from the Wangary region flowing through the Minniribbie creek is bringing nutrients and sediments into the nearshore waters, particularly Kellidie Bay	The EP NRM Boards Australian Government National Landcare Funding Project ‘Saltmarsh Threat Abatement and Recovery’ includes working with local government, local communities and landowners to address hydrological flow impacts to coastal saltmarsh sites, and work together to find on ground options to improve water flow, quality and saltmarsh  As part of the Strategic Plan for the Eyre Peninsula Natural Resources Management Region 2017–2027 the EPNRM will:  partner with seafood industry on mutually beneficial projects including water quality monitoring and works, habitat protection, and marine debris reduction and clean-up  promote holistic marine management that considers the interactions of the terrestrial environment with the marine biodiversity, seafood industries and recreational users  partner with agricultural industry to reduce water quality impacts and manage dryland salinity  support on-ground works to protect and enhance coastal and park condition including track rationalization, fencing, erosion control, access tracks, revegetation and pest control  raise awareness about coast and marine conservation including education about human impacts  protect and restore coast and marine habitats, particularly for priority areas identified in the Coastal Action Plan and Marine Parks’ plans. Sanctuary zones in Marine Parks remove the threat of extractive activities from an area and provide a high level of protection for these locations.  As recommended in the EP Coastal Action Plan and Conservation Priority Study (2011), continue to implement recommendations in Coffin Bay Foreshore Vegetation Management plan which considers the implications of uncontrolled overland flows from developments within the zone. Revegetation to control stormwater impacts on nearshore marine environments and address physically degraded areas on land such as those in which bare, actively eroding surfaces have been created which inadvertently impact on nearshore marine environments. DC Lower Eyre in collaboration with DEW, private landholders, community groups. District Council of Lower Eyre Peninsula supports, where possible, the Eyre Peninsula NRM Board continuing to work with land managers to adopt practices that reduce pollutant loads entering waterways.
Nutrient concentrations are elevated in groundwater entering the system contributing to the nutrient status of the bays[1]	Currently there is a project with a partnership between the Cummins Wanilla Basin Streamcare Group and EPNRMB to undertake creekline works in the catchment which should see improvements in water quality entering into the Douglas biounit
Urban runoff from Coffin Bay is likely to be introducing nutrients and sediment into nearshore waters.	As part of the Strategic Plan for the Eyre Peninsula Natural Resources Management Region 2017–2027 the EPNRM have partnered with local government to undertake urban stormwater planning and implementation focusing on water sensitive urban design that reduces water quality impacts. Design Flow (2010) identified alternative water sensitive urban design measures to reduce pollutants and erosion at coastal outfalls.
Failing and/or high density of onsite wastewater treatment (septic) systems in some coastal towns. Overflowing septic systems contribute nutrients to nearshore marine waters through shallow sub-surface or occasional overland flows.	New applications for land divisions are subject to District Council of Lower Eyre Peninsula Development Plan requirements for treating water in coastal area.

^[1] Schroder L 2019. Influence of groundwater discharge on marine communities in a South Australian coastal embayment. Honours thesis, Flinders University, SA.

• Download the Methods Report for the nearshore marine ecosystems monitoring, evaluation and reporting program.

These pages outline the statistical analysis undertaken for the Douglas Biounit. It should be read in conjunction with the AECR for that biounit. The methods used for the collection of the information can be found detailed in marine methods.

The habitat variables; total seagrass cover, bare sand, epiphyte and opportunistic algae were used to compare sites over the years they were monitored using Primer v7 with the PERMANOVA add-on^[1]. The data was square root transformed and all transects in a site were analysed for each year of monitoring. Principal coordinate ordination (PCO), with variables overlain as vectors was used to explore the data for groups.

The composition of sites and their similarities differences between sites and years can be seen in the separation of the sites within the PCO (Figure 1). Sites with abundant Caulerpa sp. were relatively isolated on the left side of the plot, while the seagrass dominated sites were orientated on the right side in varying densities. Changes in seagrass cover between years are somewhat masked with the large differences in composition due to sites containing high abundances of Caulerpa sp.

Figure 1   Principal coordinate ordination with vectors of habitat variables overlaid for 2014 and 2019 habitat data.

Pairwise comparisons were performed to discern which sites were different between years (Table 2). Six sites showed significant difference over the years monitored. The differences varied across sites and were due to declines in seagrass cover, increase in epiphyte and/or opportunistic algae and increased cover of Caulerpa sp. All of these findings, except increase in Caulerpa sp., can be linked to decline in condition using the disturbance gradients outlined in the Methods document^[2]. This is further supported by the elevated Fp ratios and the larger size class of phytoplankton at these sites suggesting nutrient enrichment.

The habitats outside of Point Longnose were dominated by extensive dense meadows of Posidonia spp. with most sites unchanged from 2014 (Figure 2). However, m0401 Farm Beach, showed changes over time, both positive and negative which may reflect patchy seagrass cover across the site and the variability within the monitoring years (Table 2). The seagrasses outside of Point Longnose were sparsely covered in epiphytes (if at all), and the composition of the phytoplankton communities (using the Fp ratio and size classes) suggest a low nutrient environment.

Point Drummond (m0416) is a complex rocky reef dominated by large robust brown algae (including Ecklonia radiata and Cystophora spp.) with dense and diverse red algal communities. This site is exposed to ocean swells and is very well flushed and found to be in excellent condition, consistent with 2014. Other positive signs of habitat condition are the numerous Blue Throated Wrasse (Notalabrus tetricus) and Blue Groper (Archoerodus gouldii) that were observed during the 2019 survey.

The findings in 2014 indicated that sites inside of Point Longnose were severely affected by nutrient enrichment, evidenced by the dense epiphytic algae on any seagrass, benthic microbial mats, abundant jellyfish and asicidans in places, and elevated phytoplankton (see 2014 reports here). In 2019, the condition of the habitats at many sites has declined further. Sites that previously had moderate amounts of mixed seagrass communities (eg: m0400, m0404 and m0407) had generally lost seagrass, taken over by the green algae Caulerpa spp. with any remaining seagrass blanketed in epiphytes. Many of these changes were statistically significant over time (Table 2). The phytoplankton communities showed elevated chlorophyll and the Fp ratios and the size classes of the phytoplankton were typical of nutrient enriched environments.

This region is commonly affected by upwellings which transport cool nutrient rich water from the continental shelf into coastal waters during autumn which greatly contribute to the regional productivity, but can also result in algal blooms. Recent evidence suggests that the upwellings are unlikely to be impacting the inner parts of Coffin Bay, but these areas are poorly flushed with residence times of between 80-100 days in parts^[3]. Any nutrients entering the system are likely to be retained in the system where they can impact on habitat condition.

There is overwhelming evidence to suggest that a number of sites inside Point Longnose are being affected by excess nutrients (eutrophication). This program has now observed that the composition of many of these sites has changed over relatively short period of time indicating that the system is out of balance and further degradation is likely unless substantial changes to the nutrient inputs occur.

Table 1 PERMANOVA outputs on sqrt transformed 2014 and 2019 habitat data (total SG, bare sand, epiphyte and opportunistic algae). P values of less than 0.01 were considered significant.

Source	df	SS	MS	Pseudo-F	P (perm)
Site	10	2.542E+05	25418	87.635	0.0001
Year	2	12051	6025.3	20.774	0.0001
SitexYear	13	40690	3130	10.792	0.0001
Residuals	233	67580	290.04
Total	258	3.846E+05

Table 2    PERMANOVA pairwise comparisons for each site in Douglas Biounit in 2014 and 2019. In order to be conservative p values of less than 0.01 were considered significant.

Site	Pairwise tests
m0400	Groups      t P(perm) 2010, 2014 2.1674 0.0323 2010, 2019 2.6505 0.0003 2014, 2019 1.4484 0.1021
m0401	2010, 2014 4.5881 0.001 2010, 2019 1.5391 0.124 2014, 2019 3.0947 0.001
m0402	2010, 2014 2.3981 0.0025 2010, 2019 1.5176 0.13 2014, 2019 2.5193 0.0035
m0403	2010, 2014 2.2802 0.0064 2010, 2019 9.1808 0.0002 2014, 2019 14.838 0.0001
m0404	2014, 2019 0.7615 0.519
m0407	2014, 2019 5.0263 0.0001
m0408	2014, 2019 1.9628 0.054
m0409	2014, 2019 3.4323 0.0005
m0411	2014, 2019 15.578 0.089
m0412	2014, 2019 8.5428 0.04971
m0413	2014, 2019 4.4786 0.0402

Figure 2   Benthic habitat composition for sites within Douglas Biounit for all years monitored.

Figure 3   Fp ratios for each site in Douglas in 2019. Oligotrophic conditions are considered to have an Fp ratio less than 0.3, mesotrophic conditions are above 0.3 and less than 0.7, and eutrophic conditions are signified by an Fp ratio above 0.7.

Figure 4   Size class categories of phytoplankton communities in Douglas Biounit in 2019.

While the AECR score is developed from a set of metrics outlined in the Methods document. This document outlines the key information used and additional statistical analysis undertaken to interpret the results of the AECR for these sites. It provides the confidence that the AECR score is consistent with the scientific interpretation and attempts to understand the pressures acting on the system.

This document does not outline all data collected for this program, additional data (eg: water chemistry) can be downloaded on the download data tab on the website or by contacting the EPA.

^[1] Anderson, M., Gorley, R. and Clarke, R. (2008) Permanova+ for Primer: Guide to Software and Statistical Methods. Plymouth, UK.: Primer-E Ltd.

^[2] Gaylard, S., Nelson, M. and Noble, W. (2013) The South Australian monitoring, reporting and evaluation program for aquatic ecosystems: Rationale and methods for the assessment of nearshore marine waters. Environment Protection Authority Adelaide. 79 pp.

^[3] Kaempf & Ellis 2015. 'Hydrodynamics and flushing of Coffin Bay, South Australia: A small tidal inverse estuary of interconnected bays'. J Coast. Res. 31(2), 447–456.