Dolphin Lagoon is currently experiencing a monospecific bloom of the cyanobacterium genus Synechococcus sp. (~20x106 cells/ml) the same species that has been in bloom in the Gippsland Lakes since November, 2007. This species is tolerant of high salinity levels (marine = 35 practical salinity scale) and has been shown to bloom at temperatures above about 14°C (similar to tropical Synechococcus sp.) conditions now pertaining in the Lagoon (Table 1).

The ratio of major nutrients i.e. nitrogen to phosphorous is one critical factor which will either favour or disadvantage a particular algal species e.g. high nitrogen levels will favour Synechococcus sp. over some other cyanobacteria. A complex set of other physical/chemical factors including the availability of trace elements, micronutrients, temperature, salinity, light and competition from other species, may then coincide to favour one species over another.

Several factors now favour Synechococcus sp. in Dolphin Lagoon e.g. temperature, salinity, light level (ability to survive high light levels lethal to other species) and diminished competition. It is also probable that nitrogen levels are relatively high in the Lagoon (not currently monitored).

Why has the bloom occurred now, nearly twelve months after it began in the Lakes proper? One explanation may be that the species wasn’t previously present in the Lagoon, prior to the last high tide and storm surge several weeks ago, and that Lake water driven into the Lagoon carried with it a seeding population. This is only circumstantial evidence for the hypothesis that this Synechococcus sp. is of marine and possibly sub-tropical origin and has arrived here, as have other species, on the warming southward-flowing East Australia Current.

The bloom may have little long-term effect, as it should be eliminated by the wetland drying cycle. This species is not known to produce resting cysts or spores. However in the short term, it is unlikely that any other algal species will be able to compete with it, at least not until it has exhausted the nutrients to a level that affects cell growth and that may favour other species. It is generally considered a poor food species for zooplankton, although the evidence is conflicting. Therefore there exists the possibility that the bloom may be detrimental to zooplankton and in turn other animals that rely on small crustacea for food e.g. small native fish sometimes found in the Lagoon such as Tupong, Hardyhead and Blue-spot goby, and subsequently other larger predatory fish and bird species.

Persistent monospecific blooms are a feature of a degraded environment. Unfortunately this is a familiar scenario within the Gippsland Lakes which is likely to become worse with the pressures of development and changes to climate regimes.

Table 1.

Update 03-Nov-08

Synechococcus bloom has declined although still present. Hypersaline conditions (Table 1) have triggered a bloom of the phagotrophic (non-photosynthetic) dinoflagellate Oxhyrris marina. Dissolved oxygen level has declined and is unlikely to recover before evaporation effectively dries-out the lagoon for summer – failing flood. Water is becoming acidic (lower pH) with increased CO2  (carbonic acid) and lack of oxygenation (photosynthetic species in decline).

August 3 Update

Emu parade Hardy's Rd.

Apologies: Annie & Maurice (ill)

Attendees: Jenny Meddings, Clint Eastwood, Matt Palmer, Barry Healy, Joan Kinnon & Jonathan Smith

Began at 10.00. Barry distributed safety vests and erected work sign.
We collected ~10 garbage bags of rubbish between Broadlands Rd turnoff and Metung Rd.
Predominant articles were aluminium cans - VB, MB, Bourbon & Coke. Joan also collected 1 bag on Broadlands Rd. between the entrance and the first bend.
Matt took the bags for delivery to tip on Monday.
Jonathan disturbed a black snake basking in the sun beneath a blue-box tree on Hardy's Rd.

All returned to TBLC shed at ~11.15 and had scones (bought by Barry) and tea at J&J's house.
Barry collected tubes and trays to return to Paynesville nursery and took another 12 plants for Bluff Lagoon. All dispersed at about 13.30 (6 people x 3.5 hrs)

Everyone pleased with the day and the outcome - agreed need to tackle our inner roads next.

TBLC members and guests are planning to clean-up litter along Hardy's Road between Kings Cove and Tambo Bluff on Sunday 3 August 10am-12noon.

Litter is accumulating along the roadside probably due to uncovered trailers and utes carrying rubbish to the tip and unfortunately it has to be said the occasional intentional litter-bug.

Want to join in, get a bit of exercise and meet Tambo Bluff Landcare Coastcarers?

Be at the Landcare Coastcare sign, Broadlands Road at 10 am with a safety vest and some gloves (some spares will be available).

A project entitled "Tambo Bluff Biodiversity Enhancement" has received funding. The project was initiated by Tambo Bluff Landcare Coastcare in collaboration with East Gippsland Shire Council. The funding has been received by East Gippsland Shire Council and is delivered through the Department of Sustainability and Environment under the Bush Guardian grant scheme.

The successful grant is for $3300, to be used in the control of invasive and potentially invasive species on public land within the Public Park and Reserve and Public Conservation zones of the Tambo Bluff environmental precinct.

The program will primarily be aimed at suppressing established blackberry and box thorn infestations and then providing ongoing control for as long as is necessary and practical, as well as eradicating a number of establishing weeds including Bluebell creeper and Apple of Sodom.

Timing of proposed works will relate to growing seasons of targeted weed species so as to provide the most effective control and greatest overall benefit to cost ratio. This being the case the program will begin in earnest over spring, though spraying of Bluebell Creeper has already been undertaken.

Many thanks to the Shire's Environment Department for the quality of their well-researched application and committment to the environmental health of the wetlands and other habitats at Tambo Bluff.

Tambo Bluff Landcare Coastcare held a planting day on Saturday 24 May to infill 600 understorey plants to complete a planting of 1000 trees planted in Spring 2005 surrounding Dolphin Lagoon, Tambo Bluff.

Species planted included: Sunshine Wattle, Showy Bossiea Prickly Currant Bush, Common Heath, Tangled Guinea Flower, Tree Violet, Austral Indigo, Snowy Daisy Bush, Hazel Pomederris, Yellowwood, Blackwood, Forest Clematis (glycinoides) and Wonga Vine.

Many thanks to our comrades from Lower Tambo Landcare Group for assisting on the day and to Ray and Carol for providing the creature comforts.

View online gallery to see more pictures.