Putting the reef back into Ridge Ridge Putting the reef back into - PowerPoint PPT Presentation

Putting the reef back into “ “Ridge Ridge Putting the reef back into to Reef” ” Catchment Management Catchment Management to Reef for Pumicestone Pumicestone Passage. Passage. for Restored oyster reef, Chesapeake Bay Dr Ben Diggles Dr Ben Diggles DigsFish Services Pty Ltd DigsFish Services Pty Ltd 1 1 1 1 www.digsfish.com www.digsfish.com

Future development for Future development for Pumicestone Catchment Catchment…… …… Pumicestone 2 2

We need need effective catchment effective catchment We management… … management 3 3

Is the status quo good enough ? Is the status quo good enough ? • When scale of future development is considered, • When scale of future development is considered, frankly, No. frankly, No. • The • The Pumicestone Pumicestone Catchment Management Plan Catchment Management Plan is a good start, but in it there’ ’s no mention of s no mention of is a good start, but in it there restoration of shellfish reefs… ….. .. restoration of shellfish reefs • This is despite their ecosystem benefits to water • This is despite their ecosystem benefits to water quality, biodiversity, and overall sustainability. quality, biodiversity, and overall sustainability. • Shellfish (oysters, mussels etc.) are culturally • Shellfish (oysters, mussels etc.) are culturally significant, especially to traditional owners, as significant, especially to traditional owners, as well as socially and economically important. well as socially and economically important. • In essence they tick all the boxes • In essence they tick all the boxes – – as a tool in as a tool in the management shed, they cannot be ignored. the management shed, they cannot be ignored. 4 4 4 4 www.digsfish.com www.digsfish.com

Shellfish = Ecosystem engineers Shellfish = Ecosystem engineers • Bivalves, being filter feeders, are the • Bivalves, being filter feeders, are the “ “lungs of lungs of the estuary” ”. Shellfish reefs provide the . Shellfish reefs provide the the estuary following “ “ecosystem engineering ecosystem engineering” ” services services: : following • Food and habitat for fish and crustaceans. • Food and habitat for fish and crustaceans. • Filtration of water (decreased turbidity). • Filtration of water (decreased turbidity). • Carbon sequestration (into shells). • Carbon sequestration (into shells). • Nutrient uptake (e.g. Nitrogen). • Nutrient uptake (e.g. Nitrogen). • Bentho • Bentho- -pelagic coupling (consuming nutrients pelagic coupling (consuming nutrients from water and energy from the sun (via from water and energy from the sun (via phytoplankton) and converting these into phytoplankton) and converting these into material useful to other animals in the system material useful to other animals in the system (food for fish, nutrients for seagrass seagrass). ). (food for fish, nutrients for • i.e. They are the foundation of a healthy • i.e. They are the foundation of a healthy estuary. estuary. 5 5 5 5 www.digsfish.com www.digsfish.com

Shellfish = Ecosystem engineers Shellfish = Ecosystem engineers 6 6 6 6 www.digsfish.com www.digsfish.com

Shellfish = Ecosystem engineers Shellfish = Ecosystem engineers 7 7 7 7 www.digsfish.com www.digsfish.com

Shellfish Reefs – – research highlights research highlights Shellfish Reefs •Assimilate 283% more nitrogen than mud or sand banks •Generate 1300% to 10,000% more fish and crabs than mud banks 8 8 8 8 www.digsfish.com www.digsfish.com

Declining bivalves – – global trends global trends Declining bivalves • But • But… … despite being recognised as a vital link in despite being recognised as a vital link in the estuarine food chain, natural shellfish reefs the estuarine food chain, natural shellfish reefs are at risk in many parts of the world. are at risk in many parts of the world. 9 9 9 9 www.digsfish.com www.digsfish.com

Case study- - rock oysters in rock oysters in Case study Pumicestone Passage Pumicestone Passage • Historically, Sydney rock oysters were massively • Historically, Sydney rock oysters were massively abundant in Pumicestone Pumicestone Passage. Passage. abundant in • Ninghy • Ninghy = Aboriginal word for = Aboriginal word for “ “plenty of oysters plenty of oysters” ”. . Early settlers in the mid 1800’ ’s described s described Early settlers in the mid 1800 subtidal oyster reefs down to 4+ meters and oyster reefs down to 4+ meters and subtidal intertidal reefs 300 yards long. intertidal reefs 300 yards long. • But today • But today subtidal subtidal oyster reefs are extinct and oyster reefs are extinct and around 96% of oyster zonation has been lost. around 96% of oyster zonation has been lost. • Underlying cause is due to recruitment failure • Underlying cause is due to recruitment failure from poor water quality and habitat change. from poor water quality and habitat change. Disease is the symptom, NOT the cause. Disease is the symptom, NOT the cause. 10 10 10 10 www.digsfish.com www.digsfish.com

Estuaries without bivalves – – what what Estuaries without bivalves do you get ? do you get ? • Reduced food and reef habitat for fishes and • Reduced food and reef habitat for fishes and crustaceans = unhealthy fisheries. crustaceans = unhealthy fisheries. • Reduced • Reduced bentho bentho- -pelagic coupling = poor pelagic coupling = poor utilisation of available nutrients which of available nutrients which favours favours the the utilisation algal- -microbial loop = Undesirable algal growth microbial loop = Undesirable algal growth algal and/or algal /jellyfish blooms, microbial problems and/or algal /jellyfish blooms, microbial problems in shellfish (and swimmers/ other water users). in shellfish (and swimmers/ other water users). • Increased turbidity, which reduces • Increased turbidity, which reduces seagrass seagrass growth and survival. growth and survival. • In other words, exactly what we see in • In other words, exactly what we see in Pumicestone Passage today. Passage today. Pumicestone • It can get worse: Dead zones (low or no O • It can get worse: Dead zones (low or no O 2 ) to 2 ) to come next ? come next ? 11 11 11 11 www.digsfish.com www.digsfish.com

What can be done about it ? What can be done about it ? • Obviously responsible town planning is vitally • Obviously responsible town planning is vitally important – – need catchment management that need catchment management that important reduces sediment and nutrient inputs. reduces sediment and nutrient inputs. • Riparian buffer zones / artificial wetlands to • Riparian buffer zones / artificial wetlands to recover nutrients and clean runoff/stormwater stormwater. . recover nutrients and clean runoff/ • Restoration of shellfish reefs • Restoration of shellfish reefs – – precedents from precedents from the Chesapeake Bay Program in the US are the Chesapeake Bay Program in the US are worth examining. worth examining. • Dead zones in • Dead zones in Cheasapeake Cheasapeake Bay made things Bay made things very difficult for them – – don don’ ’t let it happen here. t let it happen here. very difficult for them 12 12

Chesapeake Bay Program, USA Chesapeake Bay Program, USA • Three pronged catchment management effort to • Three pronged catchment management effort to restore their waterways. restore their waterways. • 1. Reduce Pollution • 1. Reduce Pollution At top of the list At top of the list because restored because restored • 2. Restore Habitats • 2. Restore Habitats shellfish reefs help shellfish reefs help • Restoring shellfish reefs • Restoring shellfish reefs with both 1. and 3. with both 1. and 3. • Replanting • Replanting seagrasses seagrasses as well as as well as • Restoring wetlands restoration of • restoration of Restoring wetlands seagrasses seagrasses • Restoring fish passage • Restoring fish passage (through improved (through improved • 3. Manage Fisheries • 3. Manage Fisheries water clarity) and water clarity) and wetlands (through wetlands (through http://www.chesapeakebay.net www.chesapeakebay.net/track/restoration /track/restoration http:// bank stabilisation stabilisation) ) bank 13 13

They are doing it ! They are doing it ! 14 14

Shellfish Reef Restoration in Australia Shellfish Reef Restoration in Australia • Australia • Australia’ ’s first shellfish reef restoration program s first shellfish reef restoration program has just started in Port Phillip Bay, Victoria. has just started in Port Phillip Bay, Victoria. • Partnership between a local fishing club, Victoria • Partnership between a local fishing club, Victoria Fisheries and The Nature Conservancy (TNC, an Fisheries and The Nature Conservancy (TNC, an eNGO). ). eNGO • TNC is world authority on shellfish reef restoration. • TNC is world authority on shellfish reef restoration. • They sponsored a National workshop in Melbourne • They sponsored a National workshop in Melbourne (February 2015) leading to development of a (February 2015) leading to development of a National Shellfish Restoration Strategy Document. National Shellfish Restoration Strategy Document. 15 15