Enclosure 6 - ESP Letter

                                                                                      Ecological Service Professionals
                                                                                                             Sustainable Science Solutions


Oyster Area         Calculation                         Areal Surface Area                   Assumptions/Exclusions
Oyster Leases                                                                                Tewantin are likely to be greater
                                                                                             given the area possibly occupied in
                                                                                             the lower estuary based on 5% of
                                                                                             the accommodation space within
                                                                                             historical oyster leases and proximity
                                                                                             to an indigenous shellfish midden
                                                                                             with 4 m deep oyster shells.
                                                                                             Several constraints on placement of
                                                                                             restoration structures due to various
                                                                                             external factors are outlined in the
                                                                                             Oyster Restoration Management
                                                                                             Plan

D) Current          Surface area of all living oyster   Current area of living leaf oyster   Oyster beds and reefs typically form
                                                                      2
extent of           habitat identified in field         bed = 4,050 m                        on soft substrates due to an
degraded living     assessments, based on visual                                             accumulation of shell. These dense
Oyster              inspection, sediment probing        Current area of degraded oyster      aggregations can form substantial
beds/rubble/agg     and handheld GPS location.          habitat assessed within historical   reefs >0.5m above the sediment
regation habitat                                        harvest areas (note this is not      surface. Fundamentally, with the
measured in         The locations surveyed are          equivalent to Oyster beds or         exception of the leaf oyster bed,
Noosa River         shown in appendix A and all         reefs as oysters only occur at       oyster aggregations growing on
within Historical   but sites 16 and 17 are within      low densities – Beck et al. 2009)    rocks are different habitat to oyster
Oyster Leases       the historical oyster lease         (includes: Rock/Rubble bank –        beds/reefs that grow on soft
                                                                  2
                    areas.                              15,892 m ; Coffee rock reef –        sediments.
                                                               2            2
                                                        705 m ) = 16,597 m
                                                                                             Due to the nature of equipment
                                                        Total living oyster habitat          (Figure 5), dredging would have
                                                                   2           2
                                                        (4,050 m + 16,597 m ) =              occurred over soft sediment areas
                                                                    2
                                                        20,647 m                             rather than rock/rubble so may have
                                                                                             re-suspended sediments transported
                                                                                             by floods, creating a negative
                                                                                             feedback loop and affecting oyster
                                                                                             bed recovery/ oyster recruitment
                                                                                             (although it is not possible to
                                                                                             determine).
                                                                                             Natural rock surfaces are not
                                                                                             currently suitable for recruitment of
                                                                                             dense oyster aggregations or the
                                                                                             formation of dense beds/reefs due to
                                                                                             a lack of oyster settlement on
                                                                                             horizontal surfaces (due to algae
                                                                                             and fine sediment) (TNC & ESP
                                                                                             2015), low surface area:volume ratio
                                                                                             of rubble banks; lack of small spaces
                                                                                             within the rubble; and, modern
                                                                                             requirement of oysters to grow in a
                                                                                             narrow intertidal zone to escape
                                                                                             degraded conditions.
                                                                                             Does not include aggregations of
                                                                                             oysters on jetties or seawalls which
                                                                                             are functionally not equivalent to
                                                                                             natural oyster beds/reefs. Oyster
                                                                                             aggregations growing in a thin
                                                                                             veneer on vertical surfaces are
                                                                                             limited in the extent they can grow
                                                                                             away from the vertical surface due to
                                                                                             gravity and adhesion tension. This
                                                                                             limits the potential to become three-
                                                                                             dimensional habitats. Further they
                                                                                             are often found outside the fish
                                                                                             habitat area and do not currently
                                                                                             form part of the complex natural
                                                                                             estuarine habitat mosaic (refer to
                                                                                             living foreshore concept that may
                                                                                             make this possible).

E) Current          Surface area of all identified      Current areas of bedrock with        Only a narrow intertidal band on
extent of oyster    buried oyster bank and rubble       intertidal oyster aggregations in    hard rock surfaces is occupied by
aggregations on     + bedrock in field assessments      Lake Weyba (not equivalent to        sparse oyster aggregations. This
bedrock/rubble                                          Oyster beds of reefs – Beck et       area represents all bedrock/rubble
measured in                                             al. 2009) (includes: rock rubble     so would have a considerable area
Lake Weyba                                              banks with sparse oyster

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