Shellfish reef restoration research in Pumicestone Passage
Small scale scientific trials discovered much potential for restoration of subtidal shellfish reefs in Pumicestone Passage. Initial data from 2014 found substantial recruitment of oysters (Fig. 1) fish and invertebrates to these areas. Clumps of 1000’s of fish eggs were observed only in shellfish reef material taken from subtidal collectors (Fig 2).
Fig. 1.
In 2014, clean substrate placed in subtidal areas at the right time of year attracted large numbers of newly settled oyster spat from the plankton.
Fig. 2.
Within weeks, thousands of fish eggs were deposited on new shellfish reef material, but only in subtidal areas.
Invertebrates such as mud crabs and small black grapsid crabs were 4 to 5 times (400-500%) more abundant in shellfish reef material held in subtidal collectors. Repeating these experiments in 2015 found 2600% more invertebrates in subtidal reef material compared to intertidal controls as well as 1000’s more fish larvae (Figure 3). The results of the field trials were published in Proceedings of the Royal Society of QLD.
These data suggest improvements in fish and invertebrate biomass upwards of 500-1000% (or more) could be expected if subtidal shellfish reefs could be restored in Pumicestone Passage on a large scale. This would be a similar result to those described in previous shellfish reef restoration projects conducted overseas such as oyster reefs in the USA and mussel reefs in New Zealand.
Fig 3. Micro trials conducted in 2015 again found 1000’s of fish larvae and 2600% more invertebrates on shellfish reef material deployed subtidally.
These sorts of results have lead to development of shellfish reef restoration projects in many other places including the USA, New Zealand and most recently, in Port Phillip Bay, Victoria.
For full scale trials in Pumicestone Passage, a structured research program is being undertaken to assess not only changes in fisheries productivity, but also uptake of nutrients by shellfish reefs if we are to achieve the ultimate goal of using environmental offset models to fund full scale reef restoration efforts. Under co-ordination of SEQ Catchments we have received funding from Moreton Bay Regional Council, Unity Water, Landcare, OzFish Unlimited, BCF and Pumicestone Passage Fish Restocking Association and completed Phase 1 (seafloor surveys and video transects) to identify the most suitable sites for restoration trials (see map page). We have now deployed the trial reefs which signals the beginning of phase 2 of the R&D plan.
Some of the results of the trials have been exciting, including a doubling of fish numbers in the first 6 months, increasing up to 10 times more fish after 30 months, while invertebrate monitoring after 9 months, 18 months and 2 years confirmed reliable subtidal recruitment of rock oysters and prolific colonisation by various reef dwelling invertebrates, but also damage to patch reefs from careless anchoring.
Videos of various fish species browsing on the trial patch reefs can be found at these links for patch reefs, crate reefs and BESE reef modules compared to non-restored areas. Transects of the larger patch reefs deployed in 2018 showed after 8 weeks they were securely in place and accumulating invertebrates and fish, while invertebrate surveys after 3 months, 6 months, 9 months and 12 months suggest the new trial reefs are establishing healthy invertebrate populations which include several species of rock oysters, as well as healthy fish populations. To help protect the trial shellfish reefs from damage, we ask that water users DO NOT ANCHOR in the trial area.
Phase 1 – Detailed Design and Approvals
| Task | Who (Lead) | Indicative Budget (Ex GST) |
Output |
| Sea Floor Survey – Detailed surveying of sea floor in priority site identified in prefeasibility analysis | TBA | $13,000 | High quality dataset to be used in development of approval/detailed experimental design |
| Oyster settlement studies – Conduct studies to precisely determine times of peak natural oyster spat settlement | Local oyster farmers/DigsFish | $6000 | Data on peaks of natural oyster settlement to inform planning for Phase 2 (R&D) |
| Project Steering Committee – Coordinate and facilitate a project steering committee (relevant state agencies, local council, community) | SEQ Catchments | $3000 | Bureaucratic support for the project and guidance in approval process and detailed design. |
| Approvals Process – Liaise with state agencies to map out approvals process (may include Development Approval, Designation of area as Special Activity Area or other) | SEQ Catchments/ Digsfish/ Sunfish | $14500 | Submission of project plan into approval process for consideration by authorities |
| Budget and Experimental Design – Develop detailed experimental design and budget based on goals of project and discussions with consent agencies. | Digsfish/SEQ Catchments/USC/ Sunfish | $10000 | Detailed experimental design and budget |
| Information evening – held at Toorbul with local community and interested parties to discuss the concept and build awareness and support in the broader community – also to understand any constraints from their perspective | SEQ Catchments, TFSA | $3500 | Broader community awareness and understanding of any constraints which will need to feed into the approvals process |
| TOTAL PHASE 1 | $50,000 | ||
Phase 2 – Research and Development
| Task | Who (Lead) | Indicative Budget (ex GST) |
Output |
| Baseline monitoring – Conduct baseline surveys of biodiversity, biomass and disease prior to reef restocking (includes community involvement) | USC | $50,000 | Baseline data collected for later comparative purposes |
| Shellfish reef trials – Examine several different methods of shellfish reef construction (different materials, structure/relief/water depth, maintained or set and forget) | USC, Local oyster farmers,PPFSA, DigsFish, OzFish, Sunfish | $100,000 (plus $50,000 from TFSA) | Determine most effective/cost effective methods for restoring shellfish reefs under local conditions |
| Scientific monitoring in field- of shellfish growth, survival, diseases, and fisheries productivity (recruitment of fish and invertebrates, seagrass coverage, recreational catch rates) (includes community involvement) | USC, Local oyster farmers, PPFSA, DigsFish, OzFish, BCF | $100,000 | Determine effectiveness of restored reefs for improvements in fisheries productivity /catch rates |
| Scientific monitoring in lab – measure carbon and nitrogen uptake , water quality improvements (clarity) in tank trials | JCU | $60,000 + | Determine effectiveness of restored reefs for improving water quality. Data to be used to develop environmental offset models |
| TOTAL PHASE 2 | $310,000 +, plus $50K from TFSA |
Phase 3 – Scale up to full scale reef restoration
| Task | Who (Lead) | Indicative budget (ex GST) |
Output |
| Environmental offset models– Develop models based on data from Phase 2 | TBA | $60,000 | Environmental offset models developed |
| Scaling up – Broader implementation of shellfish reef restoration in Pumicestone Passage and other areas in Moreton Bay (includes community involvement) | Currently not permitted. We need restoration to become an approved activity in Moreton Bay Marine Park | $1,000,000 + (development offsets ?) | Restoration of shellfish reefs in Pumicestone Passage and Moreton Bay at an ecologically meaningful scale |
Rod R says
It’s great that people are finally looking to restore the natural ecological balance in the Passage.