Overview of Biological Overview of Biological Issues inIssues in FundyFundy Tidal Energy Tidal Energy

Development Development

Patrick StewartEnvirosphere Consultants Limited

FORCE/OEER Workshop, Old Orchard Inn, Wolfville, N.S., October 13, 2010

Organisms rely on water movement and tides and also the structure of the aquatic environment imposed by current and tides.

Life cycles, movements, dispersal, feeding, etc. all have elements related to water movement.

Marine organisms are adapted to/ benefit from water movement in many ways:- Design of diatoms and nanoplankton to utilize stratified and unstratified water column respectively.

- Worm tube structures protruding from sediment and burrows enhance irrigation of tube by Bernoulli principle;

- Suspension feeders (e.g. mussels, sea anemones) rely mainly on particles brought to them by current.

- Wave environment concentrates larvae of barnacles and other organisms (e.g. mussels)nearshore for settlement.

- Vertical migration of zooplankton to remain positioned in an estuary.

- Use of lunar high tides for spawning by some fish species;

- Incoming tide used by fish for nearshore feeding (e.g. flounder).

- Sea scallops on Georges Bank can move with net residual current by clapping and leaving the bottom.

- Some plankton and planktonic stages rely on being retained by current structures (e.g. gyres)(Minas Basin and nearby Advocate Bay may be such features).

Irrigation of Burrows

Movement of Larval Stages to Shore

Tidal and water movement changes can affect individual organisms and ecosystems.

- changes in tide change primary productivity, current, and sediment regime which would affect productivity of the horse mussel reefs offshore at Margaretsville, and boring clams in Minas Basin (Atlantic Piddock, Barneais species at risk).

- current changes that alter circulation in nearbynearshore embayments (e.g. Advocate Bay)

- changes in tides could affect temperature regime which would affect metabolism of marine organisms.

Barnea truncata distribution in Minas Basin

Benthic Suspension Feeder Production in Inner Bay of Fundy

Currents and tidal range structure the seabed environment, sorting and distributing sediments on a gross scale (e.g. progression from coarse to fine grades in a cross section of a tidal channel) which in turn can influence distribution of benthicorganisms.

Tidal range is particularly important in the Bay of Fundy and small changes (e.g. by a tidal device array) can affect a broader extent of seabed and water column environments. An example of an ecosystem impact would be a small change in tidal range could drastically affect the area of mudflats, which would affect the distribution of certain benthic species which would impact on the feeding of shorebirds etc.

Most of the effects described above arefarfield.

The following effects are nearfield.

Interactions with Tidal FacilitiesOrganisms will interact with tidal instream devices.

- Animals move both passively (e.g. plankton, fish eggs and larvae) and actively (e.g. fish, whales, seabirds) in the vicinity of tidal devices.

- Effects could be observed from small planktonicorganisms to whales.

- ‘Elephant in the room’

- An important question is whether collisions will occur and what the impacts might be.

- Collisions could occur through small to large scales. Fish eggs though small could be damaged by shear; larger organisms (e.g. fish, whales) could be harmed by a collision. What is the risk?

Effect of Collisions

Fish and other organisms programmed to orient on structures and frequently hang around them.

Could they be delayed from normal movements on spawning migrations?

Would diving birds (e.g. loons) and harbour porpoise be attracted to the vicinity of tidal devices by schools of fish, where they would risk collision?

What patterns of movement do fish and other vertebrates show in moving through Minas Passage? How will movements be influenced by tidal devices.

Artificial Reef Effect

Could migrating species such as herring be diverted from normal seasonal movement through Minas Passage by tidal devices? Would herring be a species attracted to the turbine?

Herring spawning beds along the Parrsboroshore involve a complex and possibly ancient migration of the local population with many factors unknown.

Could the tidal devices interrupt this movement?

Impact on Migrations

Fouling organisms (seaweeds, barnacles, mussels) can develop on structures. Would seabirds/diving waterfowl be attracted to feed on the structures (common eiders and black guillemot commonly feed on mussels)?

Scuttled oil rigs have enriched benthicenvironment around them due to sloughing off of mussels, barnacles etc. Could this occur here? Would it lead to increased lobster population and maybe other species including fish.

Fouling Organisms

Benthic communities in the vicinity of tidal devices.

Community of sponges, blood star, and northern red anemone. How stable and significant are they and would they reestablish if disrupted by activity during installation or from increased organic deposition?

Species at Risk

Species that migrate through/utilize Minas Passage/ Minas Basin.

- Striped Bass- Atlantic Salmon (Inner Bay of Fundy population)- Atlantic Piddock (Barnea truncata).- Harbour Porpoise

Unique Environments/ Special Places

- Horse mussel reefs- Biological Communities in Minas Passage- Minas Passage/ Cape Split/ Cape Blomidoncultural/ historical/ tourism value

Research PrioritiesProbably should be looking for:

- tidal effects where tide is the predominant influence and other influences are minor (e.g. changes in dynamics in sheltered embayments with minimal freshwater inflow).

- effects in Minas Basin (tidal exchange greater in relation to size than in Outer Bay of Fundy).

- effects on behaviour and movement of fish in Minas Passage and near turbines.

Farfield Effects

- water movement

- environmental structure.

Summary

Nearfield Effects

-Collisions

- Artificial Reef Effect

- Migratory Patterns

- Disruption of Local Communities

-Special Places.

Numerous good questions regarding biological impacts.

Impacts range from small or negligible (e.g. primary productivity changes), to moderate (impacting significant habitats (mussel reefs) or species (e.g. boring clams); or significant (e.g. collisions with harbour porpoises or changing spawning migrations).

Choose questions that can be modeled and/or observed.

Conclusions

Overview of Biological Overview of Biological Issues inIssues in FundyFundy Tidal Energy Tidal Energy

Development Development

Patrick StewartEnvirosphere Consultants Limited

FORCE/OEER Workshop, Old Orchard Inn, Wolfville, N.S., October 13, 2010