Introduction

This document summarises the Round 1 - Initial estimates of the ACT Urban Habitat and Connectivity Project expert elicitation for freshwater fish and crayfish using the IDEA protocol (refer to Hemming et al. 2018 “A practical guide to structured expert elicitation using the IDEA protocol” and Burgman 2016 “Trusting Judgements: How to get the best out of experts”).

For each question asked in the expert elicitation, we have summarised the results. All responses from the expert elicitation remain anonymous, with visualised experts estimates being denoted by a number on the x- axis. Below each visualised estimate, the comments provided by experts are collated.

The intervals displayed are for a Three-Step Elicitation.

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Shared resources

Please click the link provided to access the PDFs and documents provided by experts in the initial estimates round

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Structural habitat metrics

The next series of visualisations relate to structural habitat metrics.

Structural habitat metrics describe how the various elements of a species’ habitat are arranged in space. For example, some arboreal species may need tree canopies a certain distance apart to be able to successfully navigate from one to the next. Another species might require grass heights of a certain amount to escape predation, whilst another species might only be able to persist within a certain distance from a water body.

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Preferred distance between tree canopies

This could be related to the amount of shade the taxon group prefers or is tolerant of in its preferred habitat, the distance an arboreal species can move from one tree to the next without going along the ground, or some other feature of the taxon groups’ general biology or life history. This metric considers the availability of both exotic and native tree species in the environment, as well as both young and mature trees (> 3m height). The answer to this question will give an equivalent score to something like “percentage canopy cover”, which might be a more familiar (but harder to map) version of this metric.

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
63 0 0.0 0 n/a 0 Freshwater_fish_crayfish tree_canopy Initial
64 15 0.0 30 Tree canopy itself adds little to fish biology other than providing some shade, possibly organic matter input and possibly shelter from avian predation. as a tree ages or falls into a waterbody it replenishes instream habitat. 60 Freshwater_fish_crayfish tree_canopy Initial
65 50 10.0 10000 While generally good riparian canopy cover is important to aquatic ecosystem function, the species we have in the ACT don’t exhibit strong site attachment to riparian cover. While definitely beneficial, its not essential in most cases. Mitigating high water temperatures is probably the main benefit in some context (eg. stagnant pools) 10 Freshwater_fish_crayfish tree_canopy Initial
66 5 0.0 100 Difficult to estimate for fish and crays. Where taxa are away from the shore, canopy cover (on the shore) is likely less important than other aquatic and abiotic factors. In edge habitats (streams and lake margins) the same principle would apply although would be influenced by habitat width; I surmise narrow (<5 m) and/or shallow (<1-2 m) streams or lake sections would be more receptive to canopy cover, especially where in-stream habitat is not very complex (no protection from terrestrial predators). 30 Freshwater_fish_crayfish tree_canopy Initial
67 25 0.0 50 canopy providing shading and shelter varies on aquatic species. Not much published that Im aware of for the urban aquatic species. more better less worst. 20 Freshwater_fish_crayfish tree_canopy Initial
69 5 1.0 100

Ryan et al 2008 (ACT) – E. armatus. Radiotracking. Diel mobility (activity, in m) and Diel range (area covered m2). Generally more activity in day than night. High site fidelity, remained within pool of initial collection. Peaks in activity at sunrise, mid morning and nightfall. Diel range varied from 0-939m2, mean = 275m2; diel mobility ranged from 0-220m, mean 94m. One individual showed dormancy i.e. no movement, and stationary phases have been reported in other crayfish (Austropotamobius spp and Astocopsis) and may have a biological basis (Webb and Richardson 2004).

O’Connor 1986 (unpublished NSW DPI report) – tagged E armatus over 3 years. Only 25/188 recaptures showed movement greater than 1km from where recorded. These long range movements ranged from 1-14km, with average of 3.5. Most however were captured within a few metres of original tagging location. Very log dispersal and small home ranges. Murrumbidgee River. 		40 Freshwater_fish_crayfish tree_canopy Initial
70 5 1.0 20 Shading is important in climate change to reduce water temps. Important to provide camouflage and energy inputs to streams. However, lack of sun can also cause problems for driving aquatic food webs with photosynthesising basis. Is also general indicator of the condition of the riparian zone - would depend on native or introduced tree canopy species though (exotic species not so good) 40 Freshwater_fish_crayfish tree_canopy Initial
Aggregated 15 1.7 1471 NA 29 Freshwater_fish_crayfish tree_canopy Aggregated

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Percentage of trees which need to be native

This relates to the composition of the urban forest or remnant woodland in terms of native and exotic trees. What percentage of trees need to be native for an area to be suitable habitat for this species group? This will relate to things such as food availability or the year-round availability of canopy cover. For some species, only native trees will be beneficial whilst other species might happily utilise any tree species as part of core habitat structure.

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
63 0 0.0 0 not applicable 0 Freshwater_fish_crayfish native_trees Initial
64 0 0.0 0 i dont thinkthis metric is important to freshwater fish or crayfish 75 Freshwater_fish_crayfish native_trees Initial
65 0 0.0 0 While aquatic macro-invertebrate communities probably benefit from higher ‘nativeness’ of riparian canopy, I am not of the view that the fish and crayfish are particularly sensitive to it, with the exception of maybe Murray River crayfish (see Fulton et al, 2009). Yabbies, Murray cod etc are all very happy with willows! 50 Freshwater_fish_crayfish native_trees Initial
66 100 0.0 100 In an ideal world all the trees would be native, however, this is not to say areas with 100% exotics are unsuitable. Exotics don’t provide many (if any) benefits over natives. Deciduous exotics can be detrimental - dropping leaf litter in autumn which can decompose underwater and consume dissolved oxygen. In terms of shade, I’d say that a leaf is a leaf, and native and exotic with the same shade % would be functionally identical, in terms of shade. 70 Freshwater_fish_crayfish native_trees Initial
67 100 0.0 100 willows and poplars are probably the most likey to provide non native cover in the urban environment and are less ideal than native species 50 Freshwater_fish_crayfish native_trees Initial
69 25 0.0 50 Detritivores - eat dead leaves that fall in water - unlikely to matter if these are from exotic or native species. Sometimes use tree roots as shelter along stream banks - willows (exotic) appear to be suitable based on personal observations of E. dharawhalus hence likely they will utilise/feed on exotic and native species equally 50 Freshwater_fish_crayfish native_trees Initial
70 100 60.0 100 see previous comment. Native have a different leaf drop profile that fuels aquatic systems differently. Often also less dense canopy in the ACT - so some sun gets through. Massive deciduous leaf drop in autumn not so good. Exotics can also mean willows which have their own ‘special’ disadvantages. 60 Freshwater_fish_crayfish native_trees Initial
Aggregated 46 8.6 50 NA 51 Freshwater_fish_crayfish native_trees Aggregated

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Preferred distance between emergent vegetation

This metric relates to the spatial distribution of emergent vegetation in waterways, which may affect things like the availability of perch sites for dragonflies, or the availability of anchoring points for frog spawn. This metric considers the availability of both exotic and native vegetation in the environment. The answer to this question will give an equivalent score to something like “percentage vegetative cover”, which might be a more familiar (but harder to map) version of this metric.

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
63 0 0 0 depending on aquatic species (not my area of expertise) 0 Freshwater_fish_crayfish emergent_veg Initial
64 500 100 1000 Emergent vegetation provides instream cover to fish and crayfish, it also supports food resources. 60 Freshwater_fish_crayfish emergent_veg Initial
65 0 0 500 Emergent vegetation is excellent habitat for many fish and crayfish. However, species like Murray cod are probably not dependent on it, preferring snags/rocks etc. Emergent veg is good habitat for Golden perch, yabbies etc. All can exist without it, but most prefer it. Dense emergent macrophytes do not appear to greatly hinder them, either. 50 Freshwater_fish_crayfish emergent_veg Initial
66 1 1 100 Tough one. If I were building an ideal waterway, I’d have regular emergent veg. However, it’s different for different (sized) species. Small fish (< 100 mm), including small species (galaxias species, carp gudgeons, pygmy perches etc), and juveniles of large species love cover - it provides shelter and food. But large species (murray cod, trout cod, mac perch, golden perch, silver perch, catfish etc) would have trouble moving through thick emergent veg. Ideally, a mixture of thick and thin areas would be ideal. 30 Freshwater_fish_crayfish emergent_veg Initial
67 30 0 200 breaks in emergent vegetation are important. Most of the habitat and flow character in freshwater is better served by complexity 20 Freshwater_fish_crayfish emergent_veg Initial
69 2 1 5

E. armatus seems generally quite site attached (although capable of longer movements) - i.e. Diel range varied from 0-939m2, mean = 275m2; diel mobility ranged from 0-220m, mean 94m (Ryan et al 2008). O’Connor (1986)* showed only 25/188 recaptures showed movement greater than 1km from where recorded and most were captured within a few metres of original tagging location. Therefore my estimate is based on their home range restriction and their need for overhanging riparian vegetation (Noble & Fulton 2016).

*Draft PhD Thesis that was never submitted but is highlighted in Gilligan et al 2007 		40 Freshwater_fish_crayfish emergent_veg Initial
70 20 0 50 Many natural waterways don’t have emergent veg. Lack of emergent veg might mean a rocky bank - which can be good. Highly species dependent on what is needed. lots of emergent veg can also be not good and might be an indicator of eutrophication. Lack of it may also suggest bank erosion - which is bad. etc. 40 Freshwater_fish_crayfish emergent_veg Initial
Aggregated 79 15 265 NA 34 Freshwater_fish_crayfish emergent_veg Aggregated

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Percentage of emergent vegetation which needs to be native

This metric relates to the composition of the emergency aquatic vegetation. What is the percentage of the emergent aquatic vegetation which needs to be native to provide suitable habitat for this taxon group?

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
63 0 0 0 n/a 0 Freshwater_fish_crayfish native_emergent Initial
64 75 0 100 i dont think that this metric is particularly important structurally, though the nativeness may affect food resource productivity. im guess that native vegetation is likely to be preferred. 50 Freshwater_fish_crayfish native_emergent Initial
65 25 0 100 There is not a lot of dominant exotic emergent macrophytes in the ACT, so hard to answer this question. Dominant species now are Phragmites etc, which are native and well liked by the native species. Similar, but exotic species would probably fill the same role in providing habitat. 10 Freshwater_fish_crayfish native_emergent Initial
66 100 0 100 Like canopy cover - I guess the presence of emergent veg is more important than the native/exotic makeup. In an ideal world it would all be native I guess, but I am not particularly knowledgeable on the effects of exotic emergent veg. 30 Freshwater_fish_crayfish native_emergent Initial
67 100 50 100 most emergent vegetation is weedy and will need to be controled the exception is probably cyperus ursinus (?) 100 Freshwater_fish_crayfish native_emergent Initial
69 20 0 50 Crayfish do eat living vegetation as well as dead vegetation and may / may not have a preference for native plant species, but there does not seem to be any published reports of this for E. armatus that I can find. Given they scavenge on a range of food sources however, a low proportion of native veg is probably not going to be a major issue 20 Freshwater_fish_crayfish native_emergent Initial
70 100 50 100 Non-native emergent veg may mean invasion by a problem weed. BUt if not a problem species, then there is the potential that native and exotic species fulfil the same role. 40 Freshwater_fish_crayfish native_emergent Initial
Aggregated 60 14 79 NA 36 Freshwater_fish_crayfish native_emergent Aggregated

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Distance found from a permanent waterbody

This metric enables mapping of the potential distribution for those species which are tied in some way to a permanent waterbody. This might be a small species which is semi-aquatic (e.g. some frogs, turtles) or a larger species which relies on permanent water to drink (e.g. some birds and mammals). How far will this taxon group be found from permanent water?

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
63 0 0 0 n/a 0 Freshwater_fish_crayfish waterbody Initial
64 500 0 5000 Fish cannot be found very far from a permanent waterbody, as they require water at all times. Crayfish may move across wet ground between waterbodies. Both fish and crayfish may use non-permanent waterbodies to move between permanent water. 65 Freshwater_fish_crayfish waterbody Initial
65 0 0 1 Rarely find native fish in waterbodies that aren’t permanent. Particularly from a natural movement/recolonisation perspective, don’t commonly see rapid recolonisation of temporary/ephemeral waterbodies. Yabbies would be the exception. 90 Freshwater_fish_crayfish waterbody Initial
66 0 0 0 Unlike almost all other taxa, fish need to be in permanent water ALL OF THE TIME. Crayfish can venture out of water to feed and scavenge over the course of 24 hrs, and could burrow down into water table or wet soil for extended periods if required. But ideally, they need permanent water. 100 Freshwater_fish_crayfish waterbody Initial
67 30 0 100 Just for crayfish. Fish obviously have 0 as however during wet period the temporary creeks become accessible between permanent areas and crayfish then have a much higher estimate 10 Freshwater_fish_crayfish waterbody Initial
69 1 0 5 Crayfish need permanent water bodies to survive so they need continuous streams and waterways. They are known to be able to disperse over terrestrial however, so if there are short distances between permanent water bodies they may be able to disperse between them (although the juveniles will probably suffer higher rates of predation than the adults if they do have to undergo frequent terrestrial movements). Genetic analyses have previously shown that there is likely to be little dispersal (Whiterod et al 2017) who estimated home ranges to be between 35-75m. Therefore local genetic structuring suggests limited opportunities for large scale dispersal, including terrestrial dispersal, meaning that distances between waterways need to be minimised. Dispersal is more likely via downstream movements of juveniles rather than over land. 60 Freshwater_fish_crayfish waterbody Initial
70 0 0 10 Fish must live in water (100% confident). Crayfish may use habitat outside the water, but realistically need to be very close to water. 70 Freshwater_fish_crayfish waterbody Initial
Aggregated 76 0 731 NA 56 Freshwater_fish_crayfish waterbody Aggregated

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Non-structural habitat metrics

The next series of visualisations relate to non-structural habitat metrics.

This section asks questions regarding the non-structural elements which dictate habitat suitability for each taxon group. These includes things such as the amount of light which is tolerable at the time the species is active, or appropriate thermal conditions.

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Maximum tolerable night-time light levels

This metric relates to the maximum tolerable light level which is associated with suitable habitat for this taxon group. It relates to the amount of artificial light provided at night in the urban environment (e.g from streetlights, or buildings). For some species, artificial light may disrupt foraging behaviours, mate finding behaviours, or circadian rhythm.

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
63 0.0 0.00 0 Species dependant, not my area of expertise 0 Freshwater_fish_crayfish night_light Initial
64 10.0 0.00 10 Some species of fish are crepuscular and nocturnal. Constant high light levels would likely impact on their ability to hunt prey. 65 Freshwater_fish_crayfish night_light Initial
65 1.0 1.00 10 No strong sense of this one. Impacts of light may be mediated by water depth, structure etc. No issues with catching fish where streetlighting etc is present, but unsure of the role of night time light in isolation 0 Freshwater_fish_crayfish night_light Initial
66 0.0 0.00 10 I have no idea here. If I were building a “field of dreams”, I would emulate natural night time light levels (full moon brightness). I cannot confidently comment on the maximum threshold before ecological interference. 10 Freshwater_fish_crayfish night_light Initial
67 0.1 0.00 10 Light at night can at as an attractant to some species particularly shrimp and small fish. note that the light levels through water drop dramatically. 20 Freshwater_fish_crayfish night_light Initial
69 10.0 0.10 20 Crayfish don’t seem to show strong diel patterns in activity suggesting that their activity is not strongly light-dependent. Ryan et al 2008 (ACT) – E. armatus was generally more activity in day than night but Ryan 2005 (unpublished) showed that activity is generally unrelated to diel variation i.e. not nocturnal. No change in activity between autumn and winter. However for E. dharawhalus our unpublished data so far indicates they are more active during the day, so only a level of street level lighting would be considered maximum. 40 Freshwater_fish_crayfish night_light Initial
70 0.0 0.00 10 likely to cause disruption. But I really don’t know anything about effect of artifical light on aquatic species. In an unknown situation - less/none is best. 20 Freshwater_fish_crayfish night_light Initial
Aggregated 3.0 0.16 10 NA 22 Freshwater_fish_crayfish night_light Aggregated

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Maximum tolerable water temperature (aquatic only)

This metric relates to the maximum water temperature which is associated with suitable habitat for this taxon group. Water temperature is the temperature which a mercury thermometer would record if it was pointed held under the surface of the water, out of direct sunlight. This metric is likely to be relevant to fish and other aquatic organisms, as well as species which lay eggs in the aquatic environment.

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
63 0 0 0 dependant on species, not my area of expertise 0 Freshwater_fish_crayfish max_w_temp Initial
64 29 2 32 this is very species specific. but my estimates are based on the annual daily maximums and minimums from the Murrumbidgee River at Halls Crossing. the river here has supported the majority of the native fish species of fish found in the ACT (with exception of some apline crayfish species). 80 Freshwater_fish_crayfish max_w_temp Initial
65 35 30 45 For water temperature in our climate to exceed ~ 30 degrees C, usually implies a relatively small, shallow water body that is not flowing. At this point, dissolved oxygen levels start to become critical. High temperature usually needs to interact with some other process (eg. biological oxygen demand) to create conditions unsuitable for fish/crayfish. Exception may be spiny crayfish that are more temperature sensitive than other organisms 50 Freshwater_fish_crayfish max_w_temp Initial
66 20 18 25 I chose approximate values which reflect temperatures I have observed in non-urbanised areas. 60 Freshwater_fish_crayfish max_w_temp Initial
67 26 6 35 Max is very dependent upon species and water quality. Variation in temp is required breeding is usually triggered by raises in temp >16oC. often with flush events. 70 Freshwater_fish_crayfish max_w_temp Initial
69 27 27 30 Maximum tolerated temperature by E. armatus = 27C (Gilligan et al 2007; Geddes et al 2003) however this is only provided that there is adequate dissolved oxygen (at least 3mg/litre) (Geddes et al 1993; Gilligan et al 2007; Whiterod & Zukowski 2019). Mating occurs in winter at temps between 12-15C (O’Connor 86). Therefore a lower estimate of 10C and upper of 27, with best at approx 12. From Whiteroad & Zukowski (2019); “Euastacus armatus have an upper lethal temperature tolerance (LT50) of 30°C and lower DO concentration of 2 mg L−1 (Geddes et al., 1993).” 60 Freshwater_fish_crayfish max_w_temp Initial
70 12 10 26 This is a seasonal question and very hard to answer in terms of actual degrees - should be in terms of % divergence from natural. It is important though - it contributes to fish breeding and if too high can cause fish kills, crayfish to exit the water etc. 20 Freshwater_fish_crayfish max_w_temp Initial
Aggregated 21 13 28 NA 49 Freshwater_fish_crayfish max_w_temp Aggregated

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Minimum tolerable water temperature (aquatic only)

This metric relates to the minimum water temperature which is associated with suitable habitat for this taxon group. Water temperature is the temperature which a mercury thermometer would record if it was pointed held under the surface of the water, out of direct sunlight. This metric is likely to be relevant to fish and other aquatic organisms, as well as species which lay eggs in the aquatic environment.

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
63 0.0 0.0 0.0 n/a 0 Freshwater_fish_crayfish min_w_temp Initial
64 5.0 2.0 10.0 As per for the maximum temperatures, this is based on annual temperature patterns of the Murrumbidgee River. 70 Freshwater_fish_crayfish min_w_temp Initial
65 7.0 5.0 10.0 Not sure of the role that low temps play, but might shape distribution of some (eg, carp gudgeon, smelt). Large waterbodies that provide good thermal refuge and hold these species tend to overwinter between the 5-10 degrees. 50 Freshwater_fish_crayfish min_w_temp Initial
66 15.0 5.0 15.0 Not entirely confident, again I have approximated values like those I have observed in non-urban areas, but unsure on thresholds before ecological interference 50 Freshwater_fish_crayfish min_w_temp Initial
67 8.0 2.0 15.0 unsure as to what highest minimum tolerable temp means so i have placed it below the trigger for spawning for most sp. but realistically it is probably higher 5 Freshwater_fish_crayfish min_w_temp Initial
69 10.0 10.0 12.0 Mating occurs in winter at temps between 12-15C (O’Connor 86). Therefore a lower estimate of 10C and upper of 12, with best at approx 10. 60 Freshwater_fish_crayfish min_w_temp Initial
70 5.0 5.0 5.0 This is hard to make sense of. See previous comment. 0 Freshwater_fish_crayfish min_w_temp Initial
Aggregated 7.1 4.1 9.6 NA 34 Freshwater_fish_crayfish min_w_temp Aggregated

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Habitat patch size and typical dispersal distances

The next series of visualisations relate to habitat patch size and typical dispersal distances.

This section asks questions regarding habitat patch sizes and typical dispersal distances for your selected taxon group.

Habitat patch size is explored for both core habitat (where the species lives full time) and corridors (areas the species might move through when dispersing, or when moving between connected habitat patches). Dispersal capability covers how far a species will typically move within and between habitat patches (e.g. within a home range), as well as how far they typically will move during a major dispersal event, e.g. when migrating or dispersing to a new home range.

The answers to these questions will help us to understand how far apart different patches of habitat can be whilst still being connected for a taxon group, as well as what the aspirations should be in terms of the total extent of connected habitat at the landscape or regional scale to facilitate typical dispersal patterns for the species. Below, we ask you to provide your upper, lower and best estimates for a range of metrics related to patch size and movement behaviour.

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Minimum suitable core habitat patch width

This metric relates to the minimum dimensions of an area which could be considered suitable core habitat for the taxon group. By core habitat, this would mean the area was able to provide all resources required by the species, including food, shelter, mates, etc.

For example, for a small mammal, the edge effects associated with a narrow strip of suburban woodland nestled between two rows of residential blocks may prevent it being classified as suitable core habitat. For an aquatic species, a stream may need to be some minimum width to provide sufficient core habitat for the species to move around in. If a core habitat patch in this instance is considered to have a rectangular shape, what would be the minimum width of the shorter side, regardless of how long the longer side might be?

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
63 0 0.0 0 Connectivity for freshwater fish, is necessary as several species will migrate upstream to breed. So access to breeding grounds and corridor connectivity is an important factor. 0 Freshwater_fish_crayfish min_width_core Initial
64 30 1.0 100 This is species specific and less important that longitudinal length of stream required. Some species only require a very small stream (crayfish, galaxiids) where some species require a larger sized patch (Murray cod, golden perch) 70 Freshwater_fish_crayfish min_width_core Initial
65 3 1.0 5 Generally for an urban waterway (not a lake or pond) to carry sufficient water to support a native fish population, will need to be at least 2m wide. Ginninderra creek comes to mind. Waterways smaller than 1m tend not to have the volume/too ephemeral to support fish population. 50 Freshwater_fish_crayfish min_width_core Initial
66 10 3.0 500 Almost impossible to recommend a taxon-wide estimate. Small fish (<100 mm) could manage in a narrow stream or small pond; large species need larger streams or waterbodies. 30 Freshwater_fish_crayfish min_width_core Initial
67 10 5.0 20 width doesnt really make sense in a linear environment like a stream or creek. 50 Freshwater_fish_crayfish min_width_core Initial
69 5 4.0 10 Based on personal observations of the width of streams I have seen E. dharawhalus and E. spinifer reside. However larger bodied individuals are more likely to need greater depths but width is porbably more uniform amongst different sized animals 40 Freshwater_fish_crayfish min_width_core Initial
70 200 1.0 1000 This is a ‘how big is a ball of string’ question. Streams obviously come in a range of widths and lakes (natural and made) can be much, much wider/longer. Effectiveness will also depend on the depth of the stream. ie 1m wide and 10cm deep won’t be great. Also highly species dependent ie crayfish vs large Murray Cod. Question probably needs to ask - in an urban context what is reasonable - max/min/best. Minimum is probably only needed. 70 Freshwater_fish_crayfish min_width_core Initial
Aggregated 37 2.1 234 NA 44 Freshwater_fish_crayfish min_width_core Aggregated

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Minimum suitable corridor habitat patch width

This metric relates to the minimum dimensions of an area which could be considered suitable habitat for the taxon group to move through, e.g. between different patches of ‘core’ habitat, or when dispersing (e.g. as a sub-adult looking for a new home range). Corridor habitat would need to provide all resources required by the species to effectively move through the urban space, e.g. suitable perch sites for birds, suitable protection from predation for mammals and reptiles.

For example, for a small mammal, the edge effects associated with a narrow strip of suburban woodland nestled between two rows of residential blocks may prevent it being classified as suitable core habitat, but it might be sufficient habitat to facilitate movement through the area. For an aquatic species, a stream may need to be some minimum width to provide sufficient core habitat for the species to move around in, however the same species may be able to navigate a narrow culvert if just being used as part of a movement corridor. If a movement corridor in this instance is considered to have a rectangular shape, what would be the minimum width of the shorter side, regardless of how long the longer side might be?

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
63 0.0 0.00 0 Dependant on species. Connectivity for freshwater fish, is necessary as several species will migrate upstream to breed. So access to breeding grounds and corridor connectivity is an important factor. Basically the 0 Freshwater_fish_crayfish min_width_corridor Initial
64 5.0 1.00 10 If this is purely for movement between habitats, width really only needs to be slightly wider than the largest individual. My upper and plausible estimates are a realistic guess. 60 Freshwater_fish_crayfish min_width_corridor Initial
65 2.0 0.00 3 Fish can move readily within stream channels provided flow conditions are suitable. Channel width expected to be less important than depth, velocity, instream obstacles, cover etc. See Starrs et al. 2016. 75 Freshwater_fish_crayfish min_width_corridor Initial
66 0.0 0.00 0 I would say the idea of corridors as described for terrestrial taxa does not fit the life-history of fish and crays. 0 Freshwater_fish_crayfish min_width_corridor Initial
67 1.0 1.00 3 fish ways and streams are occasionally 1m wide. however narrowing a wider stream to 1 m can will result in a barrier to passage 50 Freshwater_fish_crayfish min_width_corridor Initial
69 3.0 2.00 4 Same comment as previous but since the corridor is only for dispersal purposes rather than permanent territoriality I assume corridor width can be lower 30 Freshwater_fish_crayfish min_width_corridor Initial
70 2.0 1.00 50 Max upper estimate I struggle with. Highly species dependent- see last comment. 40 Freshwater_fish_crayfish min_width_corridor Initial
Aggregated 1.9 0.71 10 NA 36 Freshwater_fish_crayfish min_width_corridor Aggregated

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Minimum suitable core habitat depth (aquatic only)

This metric relates to aquatic habitat only. As per the minimum width measurements above, what is the minimum depth of a habitat patch which would enable it to be suitable as core habitat for this taxon group?

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
63 0.0 0.00 0.0 0 0 Freshwater_fish_crayfish min_depth_core Initial
64 10.0 0.10 30.0 Aquatic environments in the ACT do not really get deeper than 30m. Again, this varies between species, as small fish (including small bodied species and juveniles of large bodied species) only really require shallow environments, whereas large individuals (such as Murray cod) require at least a body depth of water (0.5m) up to usually about 10 - 15 m of water. below this depth WQ is less preferable and is generally not as productive in terms of food resources. 80 Freshwater_fish_crayfish min_depth_core Initial
65 1.0 0.25 1.5 Sufficient depth required to support instream cover for protection etc. Larger bodied species not expected to persist and recruit in shallow waters. Eg. wouldn’t expect Murray cod to successfully recruit in waterway <1m deep. Small bodied species, yes. 75 Freshwater_fish_crayfish min_depth_core Initial
66 2.0 0.00 2.0 Minimum depth on edge habitats in streams of lakes should approach a minimum of 1-2 m, or more realistically 0 m right at the edge. Need to allow waterplants to grow and provide cover, food etc. 60 Freshwater_fish_crayfish min_depth_core Initial
67 1.0 0.50 1.5 in urban lakes that can be variable the core habitat needs to be the constantly wet - in some newer lakes level variation can be 2m or more. 75 Freshwater_fish_crayfish min_depth_core Initial
69 0.5 0.35 0.6 Noble & Fulton 2017 report positive relationships between crayfish abundance and pool depth. In glide pools, a min of 0.6m is best and riffle runs a minimum of 0.35m. Fig 4 b and g 50 Freshwater_fish_crayfish min_depth_core Initial
70 2.0 2.00 20.0 Highly species dependent, ie crayfish vs fish. Crayfish can get away with small amount of water Murray Cod needs alot more. 50 Freshwater_fish_crayfish min_depth_core Initial
Aggregated 2.4 0.46 7.9 NA 56 Freshwater_fish_crayfish min_depth_core Aggregated

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Minimum suitable corridor habitat depth (aquatic only)

This metric relates to aquatic habitat only. As per the minimum width measurements above, what is the minimum depth of a habitat patch which would enable it to be suitable as a movement corridor for this taxon group?

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
63 0.00 0.00 0.0 0 0 Freshwater_fish_crayfish min_depth_corridor Initial
64 0.50 0.10 1.0 These again vary with size of individuals (or taxa). if it is purely for movement, than it really only has to exceed the depth of the individuals attempting to traverse the movement corridor. 80 Freshwater_fish_crayfish min_depth_corridor Initial
65 0.30 0.10 0.5 Fish often exhibit a willingness to undertake movement as long as sufficent water depth is available. Instream barriers (road crossings, pipes, waterfalls etc) the bigger issue. Water depth => than body depth is often sufficient. See Starrs et al. 2011, Starrs et al. 2016. Exception for crayfish that can move out of the water. 75 Freshwater_fish_crayfish min_depth_corridor Initial
66 0.00 0.00 0.0 Like I said, I don’t think the idea of habitat corridors applies anywhere near as much as is may to terrestrial animals 0 Freshwater_fish_crayfish min_depth_corridor Initial
67 0.50 0.30 1.0 large bodied native fish prefer not to get their backs out of the water 80 Freshwater_fish_crayfish min_depth_corridor Initial
69 0.30 0.30 0.6 Same comment as previous but since this is corridor habitat then a lower minimum depth is probably sufficient 40 Freshwater_fish_crayfish min_depth_corridor Initial
70 2.00 1.50 20.0 Again highly species dependent. 50 Freshwater_fish_crayfish min_depth_corridor Initial
Aggregated 0.51 0.33 3.3 NA 46 Freshwater_fish_crayfish min_depth_corridor Aggregated

Typical dispersal distance when seeking new home range/territory

This metric describes how far dispersing individuals from this taxon group will travel, usually to find a new home range or territory. This metric assumes the availability of continuous habitat.

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
63 0 0 0 0 0 Freshwater_fish_crayfish disperal_distance Initial
64 5000 100 100000 Again, this is habitat and species specific. individuals inhabiting small streams may undertake home range movements of less than 100m, whereas individuals in larger connected rivers can move home ranges in excess of 100km. 75 Freshwater_fish_crayfish disperal_distance Initial
65 1000 0 50000 Many fish are capable of extremely large movements, but probably constrained in the Upper Murrumbidgee River context. Perceive small-bodied species to not be as mobile, but no strong justification. Larval drift not expected to be a meaningful process in the ACT urban context. Given the state of local waterways, I think 1000m is justified. 10 Freshwater_fish_crayfish disperal_distance Initial
66 10000 0 50000 If I were building a field of dreams, I’d try and have at least 10 km of connected habitat - allowing large species (murray cod, trout cod, mac perch, golden perch) sufficient area over which to roam. Small species would not required anywhere near as much connected habitat, perhaps more like 100 m - 1 km would suffice. 50 Freshwater_fish_crayfish disperal_distance Initial
67 2000 25 50000 Upper limit is based on large bodied native fish which in connected systems can travel 2000km. or more. 50 Freshwater_fish_crayfish disperal_distance Initial
69 3500 1000 14000 O’connor 1986 reported that long-range movements i.e. dispersal sometimes occurred, with a range of distance from 1lm - 14km, and a mean of 3.5km. However dispersal events of this distance are likely to be rare as most adult crayfish are site attached. However juvenile dispersal particularly downstream could be quite far depending on the length of the waterway. 20 Freshwater_fish_crayfish disperal_distance Initial
70 50 30 1000 Highly species dependent. Crayfish not so far, Cod much more. So I am not sure which species type you want me to answer this for. 50 Freshwater_fish_crayfish disperal_distance Initial
Aggregated 3079 165 37857 NA 36 Freshwater_fish_crayfish disperal_distance Aggregated

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Typical movement distance within established home range/territory

This metric describes how far an individual typically moves within a suitable habitat patch. It could be considered as the distance between the centre and the edge of a home range or territory.

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
63 0 0.0 0 0 0 Freshwater_fish_crayfish movement_within Initial
64 500 30.0 1000 This metric again is very species and habitat specific. in smaller streams, that are generally less connected, typical movements of aquatic species are generally small. in larger rivers and reservoirs, daily movements can exceed 1000m. 75 Freshwater_fish_crayfish movement_within Initial
65 50 5.0 500 Variable between species. Based notionally on the results of radio-tracking studies undertaken on native fish in SE Australia 50 Freshwater_fish_crayfish movement_within Initial
66 1000 5.0 50000 Small and large fish are completely different - galaxiids may typically move <5 m, whereas mac perch, golden perch, murray cod and trout cod may move on the scale of kilometers 40 Freshwater_fish_crayfish movement_within Initial
67 1000 0.0 50000 See previous 20 Freshwater_fish_crayfish movement_within Initial
69 80 0.0 220 Ryan 2005 reported individuals of E. armatus moving over distances of 0-220m (mean 82m) within their home ranges, which were between 1800-2000m2 on average. Ryan et al 2008 reported diel mobility between 0-220m and mean of 94m. Otherwise, many individuals barely move within their home ranges as we have found for E. dharawalus (approx 6-10m per day diel mobility). 40 Freshwater_fish_crayfish movement_within Initial
70 50 10.0 100 same comment as before. I am not sure that any of my answers are meaningful. 50 Freshwater_fish_crayfish movement_within Initial
Aggregated 383 7.1 14546 NA 39 Freshwater_fish_crayfish movement_within Aggregated

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Typical capacity for movement outside of suitable habitat (in the absence of a physical barrier)

This metric aims to quantify how far this taxon group can or will typically move outside of areas mapped as suitable habitat. For example, a kangaroo might be able to cross a road, even though a road is not classified as suitable habitat, so long as there are no wildlife exclusion fences. A cockatoo might be able to move across a suburb between one suitable woodland habitat patch and another.

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
63 0 0 0 0 0 Freshwater_fish_crayfish capacity_movement Initial
64 50 0 500 For fish, they really cannot move outside of water, so the distance functionally is 0. Crayfish can move across land. my distances they can cover across land are a educated guess and would vary depending on how wet the terrain was. 50 Freshwater_fish_crayfish capacity_movement Initial
65 20 10 100 Thinking of a context is challenging. I have thought of it in the context of an urban stormwater drain, with sufficient water depth. Considering active upstream movement, rather than downstream displacement during high flows etc. 20 Freshwater_fish_crayfish capacity_movement Initial
66 0 0 0 Fish cannot move out of water, so unlike terrestrial animals who can cross a road, fish cannot leave water. Crays can undergo small overland movements, but I don’t know how far they are willing to do this, and it is not ideal as it leaves them vulnerable to terrestrial predation. 100 Freshwater_fish_crayfish capacity_movement Initial
67 0 0 15 Aquatic animals need water though crayfish will cross terrestrial barriers at times 100 Freshwater_fish_crayfish capacity_movement Initial
69 2500 1000 14000 I am using the sae indices as for max dispersal distance, as I am not clear what you consider ‘outside of suitable habitat’ i.e. outside of a water body? Or within a waterbody that isn’t preferable for them to set up a territory in? 5 Freshwater_fish_crayfish capacity_movement Initial
70 0 0 0 A fish needs water and can’t leave the aquatic environment. A cryfish can, but probably doesn’t want to be too far from water. 100 Freshwater_fish_crayfish capacity_movement Initial
Aggregated 367 144 2088 NA 54 Freshwater_fish_crayfish capacity_movement Aggregated

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Barriers to movement

The next series of visualisations relate to barriers to movement.

This is the final section of this survey. This section asks questions regarding barriers to movement in the urban space, which might be represented by vertical barriers (fences, walls, buildings, gutters), water barriers (lakes, streams, rivers), substrate barriers (e.g. concrete or bitumen) or barriers relating to the use of an area by people (traffic, pedestrians). By quantifying these barriers we can use remote sensing data to identify their location in the urban environment and demonstrate functional habitat fragmentation.

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Maximum crossable extent of paved surface (incl. concrete drains)

This metric aims to capture the distance this taxon group can move across a paved surface, e.g. concrete or bitumen. Examples might include bike or pedestrian paths, roads and driveways, concrete drainage channels, tennis courts, car parks, etc. For reptiles, for example, a taxon group may choose this substrate as a basking site but not be able to move a long distance due to the lack of suitable habitat cover to protect from predation. For fish, platypus or turtles, there may be some maximum distance a species can move through an artificial waterbody (e.g. a concrete drainage channel) between naturalised pools or streams.

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
63 0.0 0.00 0 Obviously a dry concrete surface will allow 0% fish movement. However our study found that smooth concrete surfaces that interrupt water movement (ie a stream flowing through a smooth concrete culvert) can increase the water velocity creating a barrier for fish. Rougher and wider culverts allowed fish to pass easier. 100 Freshwater_fish_crayfish paved_surface Initial
64 0.0 0.00 50 Again, fish crossing a paved surface is essentially 0m. Crayfish may be able to traverse a small distance. 75 Freshwater_fish_crayfish paved_surface Initial
65 5.0 0.00 100 Challenging to answer. Generally speaking, roadcrossings and concrete structures pose a barrier to fish movement, particularly if larger than a road crossing (provided it isn’t an obstacle). Crayfish etc may be the exception. 10 Freshwater_fish_crayfish paved_surface Initial
66 0.0 0.00 0 Fish are not moving out of water over paved surfaces. Even submerged culverts can be barriers to fish passage. 100 Freshwater_fish_crayfish paved_surface Initial
67 0.0 0.00 15 see previous 100 Freshwater_fish_crayfish paved_surface Initial
69 10.0 5.00 20 This is just based on my personal observations of a juvenile crayfish walking across a bridge that was at the time flooded with about 2cm of water. They are capable of walking along concrete as long as its submerged to some extent. 20 Freshwater_fish_crayfish paved_surface Initial
70 5.0 0.00 400 Would depend how much water is covering the artificial habitat ie low flows vs wet conditions. I am thinking of a concrete channel as example. 20 Freshwater_fish_crayfish paved_surface Initial
Aggregated 2.9 0.71 84 NA 61 Freshwater_fish_crayfish paved_surface Aggregated

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Maximum crossable height of vertical structures

This metric aims to determine how much of a vertical structure will impede movement by this taxon group. For example, turtles may not be able to climb up a steep roadside curb, however for a gecko a vertical structure equivalent to a multi-storey building may not be prevent movement. Birds may be able to cross vertical barriers of any height, unless they are flightless.

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
63 0.10 0.10 0.1 The depth of water (probably more relevant here) is the determining factor for fish to be able to pass over an obstacle in their path. A drop in water level of 10cm can prevent fish from passing (this is what I have recorded in the measurements). The exact depth of water is species dependant, however if the depth of water at the obstacle/barrier is the same depth of water in the stream that flows to and past the obstacle there is no obstruction. 100 Freshwater_fish_crayfish max_height_building Initial
64 0.05 0.00 0.2 Some fish can jump, though our native fish are not renowned jumpers. crayfish may be able to climb a very small vertical surface. 60 Freshwater_fish_crayfish max_height_building Initial
65 0.10 0.00 0.5 Native fish tend to not show tendencies to jump instream obstacles. A 10-20cm perched outlet can form a very effective barrier to fish movement. In the context where a barrier is not drowned out, > 20cm may be an sufficient barrier to movement. For discussion see Starrs et al. 2011; 2016 75 Freshwater_fish_crayfish max_height_building Initial
66 0.20 0.00 0.5 As before, if I were building the field of dreams, I’d have barriers no larger than 0.5 m vertical drop over 1 m horizontal distance. Vertical barriers are a major cause of habitat fragmentation for fishes, especially dams, weirs, culvert, fords, gauging stations and natural waterfalls. 80 Freshwater_fish_crayfish max_height_building Initial
67 0.20 0.00 2.0 Native fish dont like to jump barriers but they can be drowned out in higher flows. the highest is based on crayfish which will get out and crawl around barriers. 100 Freshwater_fish_crayfish max_height_building Initial
69 0.05 0.05 0.1 Crayfish would be able to climb over barriers but this is going to be very size dependent. Larger crays will be able to climb over larger structure than smaller crays. 40 Freshwater_fish_crayfish max_height_building Initial
70 0.00 0.00 0.1 Native fish tend not to jump out of water much, hence I put 0m, but a crayfish may be able to climb up a short amount out of water. I have not been thinking of these in previous questions as it would just confuse everything too much - but what about aquatic invertebrates? They often have a flying adult stage in addition to being able to crawl out of water. If you what me to include these, it would have to be as a separate category. 30 Freshwater_fish_crayfish max_height_building Initial
Aggregated 0.10 0.02 0.5 NA 69 Freshwater_fish_crayfish max_height_building Aggregated

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Tolerable vehicle traffic flow (incl. boats) during active period (day/night)

This metric aims to quantify the level of vehicle traffic (including boats in an urban waterbody) which would represent a barrier to this taxon group. The number should be based on the amount of traffic occurring during the species’ active part of the day or night. For example, an echidna may be willing and able to cross a road at night when there is little traffic, however during the day an increased traffic volume may result in the road (or rather, the traffic on the road) becoming a barrier for this species. A similar approach can be applied to aquatic and riparian species in terms of boat traffic.

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
63 0 0 0.0e+00 Species like Murray Cod (Maccullochella peelii) will aggressively guard nesting sites. This will make them vulnerable to fish lures (and easier to catch) in breeding seasons. 100 Freshwater_fish_crayfish traffic_flow Initial
64 2 0 5.0e+00 while it is likely that boat traffic may interrupt the foraging activities of a fish, i don’t have a good estimate of what levels would have significant impact. 30 Freshwater_fish_crayfish traffic_flow Initial
65 0 0 1.0e+03 Haven’t a clue. 0 Freshwater_fish_crayfish traffic_flow Initial
66 0 0 0.0e+00 No idea 0 Freshwater_fish_crayfish traffic_flow Initial
67 1000 100 1.0e+07 No real studies on this on australian fish but unlikley to be an issue. unless its squashing crayfish while crossing roads. 25 Freshwater_fish_crayfish traffic_flow Initial
69 15 10 2.0e+01 They crayfish are probably not affected by boat traffic so these estimates probably don’t apply 20 Freshwater_fish_crayfish traffic_flow Initial
70 0 0 5.0e+00 Sorry, really not sure here. I assume that aquatic species really would prefer not to be disturbed. There would probably be appropriate literature here. 5 Freshwater_fish_crayfish traffic_flow Initial
Aggregated 145 16 1.4e+06 NA 26 Freshwater_fish_crayfish traffic_flow Aggregated

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Tolerable pedestrian traffic flow (incl. swimming) during active periods (day/night)

This metric aims to quantify the level of pedestrian traffic (including swimmers in an urban waterbody) which would represent a barrier to this taxon group.The number should be based on the amount of pedestrians passing during the species’ active part of the day or night. A similar approach can be applied to aquatic and riparian species in terms of people swimming in a waterbody.

For example, a kangaroo may be willing and able to cross school playground at dusk in summer when there are few people about, however during winter an increased use of the school oval for organised sports in the evening may result in the grassy area becoming a barrier for this species.

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
63 0 0 0 Species like Murray Cod (Maccullochella peelii) will aggressively guard nesting sites. This will make them vulnerable to fish lures (and easier to catch) in breeding seasons. 0 Freshwater_fish_crayfish pedestrian_flow Initial
64 5 0 50 As for the previous question, its likely that the presence of a swimmer may disturb foraging of a fish species, don’t have a great estimate of what a significant impact level would be. 30 Freshwater_fish_crayfish pedestrian_flow Initial
65 25 10 500 Not sure about this one. Fish still exist in Murrumbidgee River at popular swimming locations, so people swimming is not likely to be a major problem in a large enough water body. 0 Freshwater_fish_crayfish pedestrian_flow Initial
66 0 0 0 No idea 0 Freshwater_fish_crayfish pedestrian_flow Initial
67 100000 10000 1000000 similar to the last I dont think we can reach a limit over a day - behaviour patterns and habitat occupancy may change. 90 Freshwater_fish_crayfish pedestrian_flow Initial
69 15 5 30 Swimmers could disturb crayfish during the daytime causing them to reduce their activity/change behaviour although if scared they can hide in burrows 20 Freshwater_fish_crayfish pedestrian_flow Initial
70 0 0 20 Not sure here, just a guess. 5 Freshwater_fish_crayfish pedestrian_flow Initial
Aggregated 14292 1431 142943 NA 21 Freshwater_fish_crayfish pedestrian_flow Aggregated