Introduction

This document summarises the Round 1 - Initial estimates of the Fine Scale Metrics for ACT Urban Habitat and Connectivity Project expert elicitation for small freshwater fish 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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Structural habitat metrics

The next series of visualisations relate to structural habitat metrics.

Structural habitat metrics describe the finer scale structural elements of a species’ habitat and how the various features are arranged in space. For example, some species may need access to bare ground for nesting to be able to successfully occupy a habitat patch. This would be a structural requirement.

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Preferred % cover of rocks

Access to rocky substrate may relate to things such as habitat refugia, basking sites for reptiles, or food resources (for aquatic species). What percentage cover of rocky substrate is required for an area to be preferred habitat for this taxon group?

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
23 25 10 60 the preference for rocks is species dependent: for Mountain Galaxias they are essential, for western carp gudgeon they are not very important, and for smelt they are irrelevant . Flatheaded gudgeon do not occur in the ACT (never have) 70 Small_freshwater_fish percent_rocks Initial
29 50 25 100 Rocky substrate is characteristic of upland stream systems with low sedimentation rates. Provides excellent habitat for fish as well as their food. 25 Small_freshwater_fish percent_rocks Initial
33 50 20 50 Of the relevant species possibly more relevant to Mountain Galaxias 20 Small_freshwater_fish percent_rocks Initial
34 30 0 70 Most of these species dont require rocks for their lifecycle but do benefit from habitat complexity 30 Small_freshwater_fish percent_rocks Initial
35 75 30 100 Rocky substrate provide some critical habitat for some of the target species. One example of for spawning sites for mountain galaxias, who lay eggs on and under rock substrate. Rocky substrate also provides refuge from predation and from flow. Rocky substrate also provides a hard surface for biofilms to establish on, which form the start of the food chain in many aquatic systems. 75 Small_freshwater_fish percent_rocks Initial
36 50 0 100 It’s probably more important that there is some cover/substrate present, rather than it’s exact nature. Fish will happily live in areas with 100% rocky substrate, but could also be happy with 0%, if there was other shelter/structure like vegetation present. 50 Small_freshwater_fish percent_rocks Initial
Aggregated 47 14 80 NA 45 Small_freshwater_fish percent_rocks Aggregated

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Preferred total length of coarse woody debris (>10cm diameter incl. snags, stumps)

Coarse woody debris (CWD) refers to fallen dead trees and the remains of large branches on the ground in forests, grasslands and in aquatic ecosystems. Here we define CWD as being greater than 10 cm in diameter and including snags (aquatic) and tree stumps. CWD provides structure and refugia within a terrestrial habitat and changes physical and hydraulic properties in aquatic systems. CWD needs to be considered when managing forests for biodiversity but also for managing fire risk. What is the preferred total length of coarse woody debris required in an area to be preferred habitat for this taxon group? Consider the total length in metres in a one-hectare patch.

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
23 10 0 20 Again, species specific differences apply: Mountain galaxias are not particularly dependant on CWD, and CWD is often scarce where this species occurs. For smelt, CWD is irrelevant (as a schooling pelagic taxon); for carp gudgeon CWD is not required (not a spawning substrate) and for flathead gudg CWD does provide a spawning substrate. CWD provides attachments for periphyton and hence bugs, which are a food source for all these species (to a mixed extent). CWD also provides velocity refugia in the case of high flows. When specifying a length (rather than a percentage or density) of CWD the question becomes over what quantity of habitat is the length requirement applied 65 Small_freshwater_fish cwd_length Initial
29 500 100 1000 CWD is critical fish habitat. I am uncertain of how much is a good level to have in a waterway. 10 Small_freshwater_fish cwd_length Initial
33 20 10 30 Smelt is more associated with open water. Ideally snags are habitat, which is better than no habitat. Species may use snags for cover even if they are not specifically associated with them. 20 Small_freshwater_fish cwd_length Initial
34 5 0 20 Length doesn’t really make sense length over what distance 10 Small_freshwater_fish cwd_length Initial
35 10000 100 50000

This is a hard metric to try to quantify. i have low confidence in my estimate. CWD is an important feature of many streams as it provides many functions important to the target species e.g; - refuge from predation and flow - hard substrate for biofilms to establish on

my estimates are kind of a percentage of cover for a 10 m wide river thats 100 km long (i.e. 1 ha) lower 1% cover upper 50% best 10% 		25 Small_freshwater_fish cwd_length Initial
36 1000 0 10000 Like rocks, fish could survive in areas with no logs, or a heap, depending on other available structures. 50 Small_freshwater_fish cwd_length Initial
Aggregated 1922 35 10178 NA 30 Small_freshwater_fish cwd_length Aggregated

Preferred % tree canopy cover (per ha)

The tree canopy provides structure (such as shade), habitat and resources for a range of species. Tree canopy cover may influence how a 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 accounts for the availability of canopy cover from exotic and native tree species in the environment, as well as both young and mature trees (> 3m height). Consider the percentage cover across one hectare patch.

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
23 30 0.0 75 canopy cover per hectare not overly relevant to fish, it is riparian canopy cover that is important. Canopy cover provides leaf litter that is the basis for many aquatic food webs, and also provides twig and stick fall that can be spawning sites for carp gudg. Insect fall from riparian veg is also quite important for Mountain galaxias forming on average 20% of diet, but up to ~55% in some studies. Terrestrial inverts have also been noted to form ~13% of diet for smelt in lowland floodplain studies. It must be noted the riparian-sourced insects may be from trees or shrubs, or grasses. Riparian canopy also provides shade (to ameliorate high summer water temps) and also dappled light (which be used as predation refuges for bot avian and aquatic predators). 75 Small_freshwater_fish percent_canopy Initial
29 50 5.0 90 Canopy cover is important for many reasons. It provides shading, and limits heating of the water. Its a source of allochthonous material that is food for macroinverts and terrestrial insects etc that are food for fish as well. 10 Small_freshwater_fish percent_canopy Initial
33 30 20.0 50 Linked to this would be the species providing canopy cover and the density of the cover. ie very dense canopy cover less good, variable/more open possibly better. 30 Small_freshwater_fish percent_canopy Initial
34 25 0.0 90 Some shading would be of benifit to most species and also hinder the localised abundance of pest gambusia. 50 Small_freshwater_fish percent_canopy Initial
35 75 10.0 100 Shading provides a range on functions for rivers and streams. it provides a source of carbon for the beginning of the food web, food inputs from terrestrial insects, addition of refuge habitat in terms of fallen trees and branches, cover from avian predation, and control of water temperature. 70 Small_freshwater_fish percent_canopy Initial
36 50 0.0 100 Same again, it all depends on the other available structures (terrestrial and aquatic) in the area as to how much shelter needs to come from shade. Shade is important for making sure streams don’t get too hot 60 Small_freshwater_fish percent_canopy Initial
Aggregated 43 5.8 84 NA 49 Small_freshwater_fish percent_canopy Aggregated

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Preferred % cover of below surface vegetation (aquatic only)

This could be related to the amount of food resources the species group prefers or is tolerant of in its preferred habitat, the distance an aquatic species can move from one below surface vegetation patch to the next without being exposed to predators, or some other feature of the species groups’ general biology or life history. This metric considers the availability of both exotic and native below surface vegetation species in the aquatic environment.

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
23 40 5.0 80 submerged veg is very important for carp gudg as it provides feeding source for bugs, spawning sites and shelter. For galaxias provides important shelter from predators and flow. For smelt it is not that important 75 Small_freshwater_fish percent_below_veg Initial
29 25 10.0 75 Instream vegetation is important habitat for fish and their food. Some species have a strong preference for vegetation (eg piggy perches) while others are open water specialists (eg. smelt). Having a diversity of habitats is important 20 Small_freshwater_fish percent_below_veg Initial
33 30 20.0 50 Western carp gudgeon can be associated with water plant beds. 30 Small_freshwater_fish percent_below_veg Initial
34 50 1.0 80 Many of these species use or associate with macrophyes heavily - however Australian smelt and western carp gudgeon can be very common in open water. 50 Small_freshwater_fish percent_below_veg Initial
35 25 0.0 100 Aquatic vegetation provides an important form of cover (flow / predation) as well as spawning habitat for carp gudgeon (and flatheaded gudgeon). it also provides good habitat for prey items (micro/macro invertebrates) 60 Small_freshwater_fish percent_below_veg Initial
36 50 20.0 100 I’d say fish really need some veg for shelter and food. But again, depends on what other habitat structure is around. 50 Small_freshwater_fish percent_below_veg Initial
Aggregated 37 9.3 81 NA 48 Small_freshwater_fish percent_below_veg Aggregated

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Physical chemical properties

The next series of visualisations relate to physical chemical properties.

Physical chemical properties mostly relate to the aquatic environments or soil.

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Preferred electrical conductivity (aquatic only)

Electrical conductivity is a measurement of the total combined salts/minerals in water and is used as a proxy for salinity. This metric seeks to determine the preferred electrical conductivity for the taxon group.

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
23 100 10 1000 Conductivity not that important to carp gudg as they can occur in extremely saline streams in the Canberra region. Similarly for mountain galaxias, can occur in relatively high conductivity and down to very low conductivity (alpine streams) 80 Small_freshwater_fish elec_cond Initial
29 250 50 5000 EC in the ACT region well monitored by waterwatch. Upland streams tend to have low (<1000us/cm) EC. EC that is too low will apply high levels of osmotic stress on fish. Im not aware of any significant sensitivity by fish to EC within the ranges of EC we see here. 50 Small_freshwater_fish elec_cond Initial
33 50 50 200 Contributes general indication of overall water condition. Best value is ideal and probably not achievable in the urban environment. 10 Small_freshwater_fish elec_cond Initial
34 100 30 2000 Mountain galaxias can occur in very low conductivty waters. pygmy perch and carp gudgeon can survive very high conductivities that are not seen here in the ACT. 75 Small_freshwater_fish elec_cond Initial
35 100 10 350

my estimates are based on WQ monitoring of the upper Murrumbidgee over the past 25 years. the value of 350 is the trigger value for the upper M’bidgee, so thats where i have set the maximum. Note, that tolerances can vary base don life history stage, with eggs and early larvae often less tolerant than adult life stages.

James, K.R., Cant, B. and Ryan, T., 2003. Responses of freshwater biota to rising salinity levels and implications for saline water management: a review. Australian Journal of Botany, 51(6), pp.703-713. 		50 Small_freshwater_fish elec_cond Initial
36 400 0 1000 I’m pretty sure this is roughly the values I have seen. 50 Small_freshwater_fish elec_cond Initial
Aggregated 167 25 1592 NA 52 Small_freshwater_fish elec_cond Aggregated

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Preferred pH level (alkalinity; aquatic only)

A measure of the acidity or basicity (alkalinity). This metric seeks to determine the preferred pH level for the taxon group. The range goes from 0 to 14, with 7 being neutral. pH of less than 7 indicates acidity, whereas a pH of greater than 7 indicates a base. The pH of water is a very important measurement concerning water quality.

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
23 7.0 6.0 9.0 pH not that important provided it stays between 6 and 9. Above 10 is lethal to fish 80 Small_freshwater_fish pH_level Initial
29 7.0 6.0 8.0 Most waters in the ACT region range between 6 and 8. 7 is neutral. 20 Small_freshwater_fish pH_level Initial
33 7.0 6.0 9.0 pH either side of neutral not so good. The further you get from 7 the worse it is. 10 Small_freshwater_fish pH_level Initial
34 7.2 6.5 8.1 No some small fish (oxleyan pygmy perch and dwarf galaxias) can endure very low pH but not usually these species. 80 Small_freshwater_fish pH_level Initial
35 7.0 6.5 7.5 pH outside of species tolerances can have deleterious effects on biology and ultimately lead to death. the values i’ve put up here are the general trigger range values for he upper M’bidgee, with the best estimate being the midpoint. 75 Small_freshwater_fish pH_level Initial
36 7.0 6.0 8.0 Pretty sure this is roughly what I have seen. 50 Small_freshwater_fish pH_level Initial
Aggregated 7.0 6.2 8.3 NA 52 Small_freshwater_fish pH_level Aggregated

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Preferred siltation levels

Siltation is water pollution caused by particulate terrestrial clastic material, with a particle size dominated by silt or clay. It refers both to the increased concentration of suspended sediments and to the increased accumulation (temporary or permanent) of fine sediments on stream or waterbody bottoms where they smother instream vegetation and cobbling occurs. Siltation is most often caused by soil erosion or sediment spill. This metric seeks to determine the maximum tolerable siltation for the taxon group within suitable habitat.

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
23 35 5.00 80 the species vary dramatically: galaxiids need clean substrates to spawn on (rocks below riffles) carp gudg and smelt can occur in highly silted environments. Preferred figure given is for galaxiids 70 Small_freshwater_fish max_siltation Initial
29 10 0.00 50 Some siltation is good from a productivity point of view. However smothering of gravel/cobble/boulder habitat is bad. 20 Small_freshwater_fish max_siltation Initial
33 10 0.00 20 Ideally less is better. Some species not so reliant on substrate condition (ie siltation can represent poor quality substratum). 10 Small_freshwater_fish max_siltation Initial
34 10 0.00 60 measure doesnt make total sense but seen as 0 low and 100 extreme (siltation basin). Most species can tolerate or excel in some sedimentation - Galaxias are probably the most sensitive. 10 Small_freshwater_fish max_siltation Initial
35 10 0.00 70 Siltation may have a deleterious affect on species that rely on interstices for spawning habitat (e.g. mountain galaxias). it also has a negative effect on the prey items available, with heavily silted areas having drastically reduced and simplified macroinvertebrate communities. 50 Small_freshwater_fish max_siltation Initial
36 10 0.00 100 Siltation generally doesn’t enhance fish habitat, but siltation alone doesn’t necessarily mean it’s completely ruined (eg if there is veg or woody debris around). Generally though, the less siltation the better. 60 Small_freshwater_fish max_siltation Initial
Aggregated 14 0.83 63 NA 37 Small_freshwater_fish max_siltation Aggregated

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Preferred tolerable turbidity

Turbidity is the degree of suspended solids in water that gives it a muddy colour. High concentrations of particulate matter affect light penetration, ecological productivity and habitat quality. This metric seeks to determine the preferred level of turbidity for the taxon group.

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
23 20 10.0 400 Turbidity not really my bag ( I dont quantitatively measure it much)Smelt can exist in very high turbidity, as can carp gudg. Mountain galaxias are more common in upland, low turbidity environments, probably because these environments are correlated with intact riparian veg and rocky substrates (spawning sites). High turbidity usually means high sedimentation rates which smother galaxias spawning sites 50 Small_freshwater_fish max_turbidity Initial
29 10 10.0 50 Turbidity may have a range of physiological and behavioural impacts. Physiological include impacts on gill function, while behavioural may include impairment of visual systems using in finding prey. Naturally our systems should have been very low turbidity. High turbidity may lead to siltation/sedimentation of instream habitats. 20 Small_freshwater_fish max_turbidity Initial
33 5 2.0 30 Not sure how to answer this. Ideally the lower the better. Some species are more tolerant of higher turbidity and may even use this as a form of cover. Mountain Galaxias, not surprisingly, often associated with better water quality/turbidity. 20 Small_freshwater_fish max_turbidity Initial
34 15 0.0 150 upper estimate is not very confident and based on long term exposure not flush events. Galaxias are not normally found in turbid systems but gudgeons can be. 50 Small_freshwater_fish max_turbidity Initial
35 10 0.0 100 Turbidity can affect foraging efficiency of fish, though most of the target species are able to persist in systems with reasonably high turbidity (e.g. carp gudgeon / australian smelt 60 - 100 NTU). Mountain galaxias are possibly most used to clearer waters based on their current distribution. 60 Small_freshwater_fish max_turbidity Initial
36 20 0.0 500 Fish seem to be able to tolerate turbidity pretty well, but it would maybe be more important for aquatic veg, which could influence fish numbers. 50 Small_freshwater_fish max_turbidity Initial
Aggregated 13 3.7 205 NA 42 Small_freshwater_fish max_turbidity Aggregated

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Preferred dissolved oxygen concentration

The amount of oxygen present within water, either presented as an absolute amount (mg/L) or as a percentage of the total oxygen saturation at a given temperature

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
23 7.0 3.5 10 as long as it is above about 6 then all should be good 80 Small_freshwater_fish dissolved_oxygen Initial
29 8.0 4.0 12 Low DO is bad for fish, though mostly for larger bodied species. A healthy stream in the ACT region will generally have a high (>80%) oxygen saturation. 50 Small_freshwater_fish dissolved_oxygen Initial
33 10.0 4.0 12 . 20 Small_freshwater_fish dissolved_oxygen Initial
34 6.0 3.0 10 below 4 mg/l is stressfull to most fish although small bodied fish particuarly pygmy perch and some others can deal with it for long periods of time. upper limit is rubbery 80 Small_freshwater_fish dissolved_oxygen Initial
35 8.0 4.0 11 my values are based on generic fish tolerance values, and the maximum values ive observed during my years of monitoring. at 4mg/l fish can start showing signs of stress. my values are set at the chronic level for low, not acute, some fish can survive lower DO (1 - 2 mg/l) for very short periods by adapting behaviour (gulping at the surface). 75 Small_freshwater_fish dissolved_oxygen Initial
36 7.0 3.0 12 I think these are the approximate values I have seen in the field. Fish can tolerate low (<7 mg/L) dissolved oxygen, but you can’t have too much. Of course it depends on water temp too. 50 Small_freshwater_fish dissolved_oxygen Initial
Aggregated 7.7 3.6 11 NA 59 Small_freshwater_fish dissolved_oxygen Aggregated

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Ammonia Nitrates

When ammonia is present in water at high enough levels, it is difficult for aquatic organisms to sufficiently excrete the toxicant, leading to toxic buildup in internal tissues and blood, and potentially death. This metric seeks to determine the maximum tolerable ammonia levels for the taxon group within suitable habitat

EDIT: We amended this in a later survey to nitrates When nitrates are present in water at high enough levels, excess nitrogen can cause overstimulation of growth of aquatic plants and algae. Excessive growth of these organisms, in turn, can clog water intakes, use up dissolved oxygen as they decompose, and block light to deeper waters.

The waterwatch CHIP report puts the following nitrate levels as water quality CHIP thresholds (mg/L): Excellent < 1.0; Good 1.0 – 1.3; Fair 1.4 – 1.7; Poor 1.8 – 2.6; Degraded > 2.6

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
23 0.00 0.00 0.0 i have little knowledge of ammonia 1 Small_freshwater_fish ammonia Initial
29 1.00 0.00 10.0 While nitrates have no known negative impact on fish at the low levels described here, a healthy ecosystem in the ACT region will have very low levels of nitrate present in the water. Any nitrate levels exceeding 10mg/L probably indicates a significantly impaired waterway. 20 Small_freshwater_fish ammonia Initial
33 0.20 0.20 3.0 Not sure how this relates to fish preferences other than it is a general indicator of water quality and catchment condition. 10 Small_freshwater_fish ammonia Initial
34 1.00 0.50 2.6 high nitrogen and therefore plant growth isnt necessarily bad for small fish 20 Small_freshwater_fish ammonia Initial
35 1.00 0.00 2.6 these are just based on the guideline values from the CHIP. 50 Small_freshwater_fish ammonia Initial
36 0.00 0.00 0.0 I have no idea about nitrates 1 Small_freshwater_fish ammonia Initial
Aggregated 0.53 0.12 3.0 NA 17 Small_freshwater_fish ammonia Aggregated

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Preferred water velocity

Water velocity relates to the speed at which water flows through aquatic habitats. This metric might influence suitability of habitat for breeding or foraging behaviour for fish and other aquatic species. What is the preferred water velocity for the taxon group within suitable habitat?

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
23 1.00 0 3.0

preferred velocity is less than 1, but wont accept decimal points. Where is water velocity measured (surface, and 0.6 depth, bottom) makes huge difference

substrate diversity, position in stream (ie mid or edge) and aquatic veg provides velocity refuge which fish will seek out in high flow 		75 Small_freshwater_fish water_velocity Initial
29 0.20 0 1.5 Water velocity interacts with multiple life history processes within fish, as well as their food. While ucrit swimming speeds may inform max water velocities for persistence in laminar flow environments, breeding habitat in riffles etc may require higher water velocities to promote egg development etc. For small-bodied fish, ucrit speeds are in the order of 2BL/s, hence my best estimate of 20cm/s. Noting that burst speeds for larger bodied species in the order of 1-2m/s are possible. 50 Small_freshwater_fish water_velocity Initial
33 0.10 0 0.2 These smaller species are often found in still/low flow waters. Mountain Galaxias are different generally found in faster flowing upland streams - but are found in low flow waters also. 20 Small_freshwater_fish water_velocity Initial
34 0.50 0 6.0 Many of these species can exist in still waters. 80 Small_freshwater_fish water_velocity Initial
35 0.10 0 1.0 This is a tricky one, as its the heterogeneity of velocities that is likely more important than any one value. some flow if ‘good’ (DO regulation etc), constant very high velocities (>0.5m/s) would likely have a negative effect (energetic requirements would be very high). Though some short term high velocity events are often important for physical habitat maintenance (i.e. cleaning riffle habitats of silt or scouring out deeper refuge pools). 20 Small_freshwater_fish water_velocity Initial
36 1.00 0 3.0 Depends on lake/stream environment obviously. I wouldn’t say there is an ideal velocity; ““good”” stream habitats usually have a mix of velocities ranging from still water to fast (>3 m/s). 50 Small_freshwater_fish water_velocity Initial
Aggregated 0.48 0 2.5 NA 49 Small_freshwater_fish water_velocity Aggregated

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Preferred water turbulence

This metric refers to rapid movement of water in several directions at once, like the water movement in a rapid. The turbulence at the air/water interface is where the oxygen gas exchange takes place but high turbulence may prevent species from permanently occurring in a habitat. What is the preferred water velocity for the taxon group within suitable habitat?

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
23 0.0 0 0 have no experience in measuring turbulence. carp gudg and smelt are low turbullence species, galaxias can tolerate turbullence but would escape it be seeking flow refuges 1 Small_freshwater_fish water_turbulence Initial
29 10.0 0 100

This one is a bit tricky. W/m3 I calculate as velocity/m3 - hence if flow velocity of 100cm/s into a 1m3 area will be 100W/m3

From the fishway literature, we know that excess turbulence can be an issue, however the finescale features of turbulence are important, as is the size of the size of the fish. In a crude sense, 100W/m3 is a relatively high level of turbulence I think? 		1 Small_freshwater_fish water_turbulence Initial
33 0.0 0 0 Probably prefer low turbulence for smaller species. 1 Small_freshwater_fish water_turbulence Initial
34 5.0 0 100 No experience in applying to these species or understanding of the measure. Some variation and complexity over a reach (100s of m) in turbulance is desirable. 1 Small_freshwater_fish water_turbulence Initial
35 0.0 0 0 I have never considered turbulence a factor for fish habitat. 1 Small_freshwater_fish water_turbulence Initial
36 0.0 0 0 No idea about watts/m3. I would say “some” turbulence is good, rather than a single strong flow in one direction (like in a concrete drain). 1 Small_freshwater_fish water_turbulence Initial
Aggregated 2.5 0 33 NA 1 Small_freshwater_fish water_turbulence Aggregated

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Habitat function and risk management

The next series of visualisations relate to habitat function and risk management.

This section asks questions regarding habitat function and risk management for your selected taxon group.

These metrics describe what sorts of risks need to be managed within habitat areas to retain habitat function. The responses to these questions will aid in the identification, design and restoration of habitat patches and connectivity corridors in the urban space, provide an evidence base for policy decision making, and set thresholds for management intervention.

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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Preferred noise levels (during active period)

Anthropomorphic noise may impact on habitat suitability for native fauna by creating disturbance or interrupting communication pathways. This metric seeks to determine the level of anthropomorphic noise preferred by the taxon group. Sources of noise might include commercial or residential areas, traffic, or other human based sources. This metric should be based on the long-term ambient noise level during the day, and exclude short-term sounds, such as cars backfiring in a parking lot. Noises such as school bells, concerts, or sirens would all contribute to the mean noise level.

Decibels: 0 threshold of human hearing, 20 quiet room, 60 busy street, 80 loud radio, 100 subway train, 110 industrial noise, 120 jet plane take-off, 130 gun shot. Remembering that decibels are described on a logarithmic scale.

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
23 0 0.0 0 I have no experience in assessing noise quantitatively. Noise is not generally considered a significant threat to fish. An exception is research that shows fish can hear outboard motors and move away from such noise. recent research shows that fish make noise (grunts, clicks etc) so for some species is likley a useful communication method. No info available for target sp that i am aware of fast flowing streams are noisy, so suggest fish are not that sensitive to noise in small, fast streams 1 Small_freshwater_fish noise_level Initial
29 20 0.0 60 Don’t know much about this, but natural background noise levels are probably fine 10 Small_freshwater_fish noise_level Initial
33 40 20.0 100 is this also vibration caused by the noise making processes. 10 Small_freshwater_fish noise_level Initial
34 0 0.0 100 not likley to impact fish. 50 Small_freshwater_fish noise_level Initial
35 0 0.0 0 extremely likely to be unimportant. 1 Small_freshwater_fish noise_level Initial
36 50 0.0 100 I wouldn’t say it is overly important, as long as it isn’t extremely loud. But I have never looked into the effects of anthropogenic noise on fish survival/reproduction etc. 20 Small_freshwater_fish noise_level Initial
Aggregated 18 3.3 60 NA 15 Small_freshwater_fish noise_level Aggregated

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Minimum tolerable fire interval

Fire can impact on habitat suitability either by influencing core habitat structural elements (such as ground and mid-storey complexity) or by causing direct mortality to individuals or populations. This metric seeks to determine the minimum tolerable fire interval (assuming low-moderate intensity burns on a patchy sub-hectare scale) before there is an impact on resident species. The assumption is that fire is applied during the active period for the species (e.g. during daylight hours on a warm day for grassland reptiles). We encourage you to leave additional notes around any additional considerations you feel are necessary to support your response.

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
23 15 2 100 Direct mortality from fire is negligible: it is the interaction between fire severity, intense rainfall and burnt catchments that is the risk, because it results in excessive sedimentation after severe fires. coolish managed burning that does not result in total removal of catchment veg, or excessive ash generation is ok. Sedimentation after fire fills pools and it may take decades or centuries for impacted streams to recover. Sedimented pools removes temperature refugia, smothers breeding and feeding habitats, and if fire is severe or frequent, riparian veg is lost which then removes shading 70 Small_freshwater_fish fire_interval Initial
29 60 24 240 Fire may play a role in terms of nutrient and pollutant inputs into streams, as well as contributing to low DO events in the event of rain immediately post-fire. Increased yields of sediment/ash etc can lead to sedimentation of key habitat, and excess nutrients contribute to eutrophication. Some fire is probably ok/beneficial. 10 Small_freshwater_fish fire_interval Initial
33 24 12 36 I am really unsure about this. How realistic is this for an urban stream or lake? 10 Small_freshwater_fish fire_interval Initial
34 48 12 80 Best based on ~ 2 generation times of known species. 20 Small_freshwater_fish fire_interval Initial
35 60 24 120 after effects of severe fires can be devastating on aquatic environments, with DO dropping to lethal levels and habitats being covered in sediment stripped form the unvegetated catchment. giving organisms and habitats a few years between fires allows some habitat and population recovery (most species are annual spawners so will take a few years to recolonise and reproduce). Fire is a natural part of the Australian landscape, so some fire is positive as it promotes regeneration of riparian habitat 35 Small_freshwater_fish fire_interval Initial
36 36 12 60 The fire itself doesn’t affect fish as much as the post-fire effects of sedimentation (mainly), and reduced water quality. It all depends on the intensity of the fire, and whether there is overland flow from rain run off immediately after the fire. Low-intensity fires with little/no run off could be tolerated by fish frequently, whereas high intensity fires with lots of run off (like we had in 2019/20) could potentially wipe out populations in small streams. 20 Small_freshwater_fish fire_interval Initial
Aggregated 40 14 106 NA 28 Small_freshwater_fish fire_interval Aggregated

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Maximum tolerable level of redfin presence

Redfin are a medium-sized fish (e.g. to 400mm FL) and are highly piscivorous. They will eat everything they can fit in their mouths and hence can impact on habitat suitability and function for other aquatic native species. This metric seeks to determine the maximum density of Redfin which can persist in an ecosystem ) before an impact on habitat suitability is anticipated for other resident species.

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
23 0.0 0 15.0 redfin presence can be tolerated id sufficient refuge habitat is available (cobble substrate, or dense submerged veg). carp gudgeons can survive in moderate to high redfin density, as can smelt, but not aware of many instances where mountain galaxias coexist (but this may be habitat or trout related rather than redfin) 80 Small_freshwater_fish redfin_presence Initial
29 0.0 0 1.0 Once detectable they are probably having an impact. Redfin are highly piscivorous. Do not want them 20 Small_freshwater_fish redfin_presence Initial
33 3.0 0 10.0 Zero redfin is best, but how likely this is in an urban environment is almost zero. I am also not sure about how we can manage the presence/density of Redfin. 15 Small_freshwater_fish redfin_presence Initial
34 0.0 0 5.0 some fish might survive higher densities but not idal 80 Small_freshwater_fish redfin_presence Initial
35 0.0 0 0.1 Redfin are voracious predators, and the lower the density the better for the target native fish species. Most of these species have been shown to exist with redfin present, so some level of redfin presence may still be tolerable. 75 Small_freshwater_fish redfin_presence Initial
36 10.0 0 100.0 Redfin don’t do native fish any favours, but some species can tolerate them in the same environment. Some native species however, such as Macquarie Perch, have been known to completely disappear when redfin numbers increase - this is related to the EHN virus which redfin are a vector for, and completely wipes out Mac Perch. 50 Small_freshwater_fish redfin_presence Initial
Aggregated 2.2 0 21.9 NA 53 Small_freshwater_fish redfin_presence Aggregated

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Maximum tolerable level of carp presence

Carp are a large-bodied invasive fish species, best thought of as ecosystem engineers due to their impact on the structure and function of aquatic ecosystems, competition with other fish species for resources, and simplification of food webs. This metric seeks to determine the maximum density of European Carp which can persist in an ecosystem before an impact on habitat suitability is anticipated for other resident species.

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
23 10.0 0 50 Carp not a major threat to these species 75 Small_freshwater_fish carp_presence Initial
29 0.0 0 1 Direct impacts by carp are not well known, but their impacts on habitat are relatively well established. Do not want to detect them, noting that their populations readily grow. 20 Small_freshwater_fish carp_presence Initial
33 1.0 0 5 Zero carp is best, but how likely this is in an urban environment is almost zero. I am also not sure about how realistic it is to manage carp, given past experience where carp removal efforts were soon followed by the public re-introducing carp. 15 Small_freshwater_fish carp_presence Initial
34 0.0 0 10 high carp density impacting on habitat and water quality. 50 Small_freshwater_fish carp_presence Initial
35 0.0 0 10 Carp have the potential to negatively affect the target species by predating upon eggs and early larvae / juveniles, as well as disturbing eggs, decreasing wq and changing habitat (suspending sediment, reducing plant growth). In reality, all of these species can coexist with carp, but no carp would be best. 65 Small_freshwater_fish carp_presence Initial
36 10.0 0 30 Carp aren’t good for native fish, but as we can see they can coexist. The less carp the better, but I don’t know of a “maximum limit” that native fish could tolerate. 50 Small_freshwater_fish carp_presence Initial
Aggregated 3.5 0 18 NA 46 Small_freshwater_fish carp_presence Aggregated

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Maximum tolerable level of gambusia presence

Gambusia are highly aggressive and are very strong competitors with other small bodied and juvenile fish. This metric seeks to determine the maximum number of Gambusia which can persist in an ecosystem before an impact on habitat suitability is anticipated for other resident species.

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
23 2 0 200 what sort of net is being considered here? (bait trap, mesh size??) all of these species can survive in the presence of redfin. Increased habitat complexity will likely mediate interactions between gambusia and these species. Smelt largely unaffected (as a pelagic mid water species) carp gudgeons more edge occupiers so likely to interact more. 50 Small_freshwater_fish gambusia_presence Initial
29 0 0 1 Nasty little buggers. Fin nipping etc. Not good for small native fish or juveniles of large-bodied species. Tend to boom in good conditions. Don’t want to detect them! 20 Small_freshwater_fish gambusia_presence Initial
33 2 0 10 Same comment as for Redfin and Carp. 10 Small_freshwater_fish gambusia_presence Initial
34 0 0 50 estimates on density of gambusia is not great locally, however known to impact health of small native fish. 60 Small_freshwater_fish gambusia_presence Initial
35 0 0 5 as per the other alien species, most of the target native species can co-exist with gambusia. having said this, gambusia have a negative effect on native fish by predating upon eggs and larvae, harassing and fin nipping larger fish and exclusion from key habitats. 0 gambusia would be best. 65 Small_freshwater_fish gambusia_presence Initial
36 20 0 500 Less gambusia the better, but most fish seem to be able to somewhat tolerate them. Depends on how many other fish are in the area (density of native fish vs gambusia) and habitat complexity I would say. 50 Small_freshwater_fish gambusia_presence Initial
Aggregated 4 0 128 NA 42 Small_freshwater_fish gambusia_presence Aggregated

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Maximum tolerable level of oriental weather loach presence

The impacts of weather loach on small freshwater fish are not well known. Weather loach possibly carry parasites and have the potential to be egg predators for species that lay their eggs on the substrate. This metric seeks to determine the maximum number of weather loach which can persist in an ecosystem before an impact on habitat suitability is anticipated for other resident species.

Expert Best Lower Upper Comments Confidence Taxon Variable Group2
23 5.0 0 50 ditto to Gambusia: what sort of net? (they are usually electrofished). Weatherloach can coexist with smelt and carp gudg, some very limited evidence that they may impact galaxias (potential egg predator and food competitor) 70 Small_freshwater_fish loach_presence Initial
29 0.0 0 1 Not much known about their impacts. Tend to be a bottom dweller/mud cruncher. Possible egg predator for demersal eggs, but limited empirical evidence. Otherwise impacts not well known. 10 Small_freshwater_fish loach_presence Initial
33 0.0 0 2 Don’t have much experience with catching them - so hard to estimate. The environmental impact of the species is unclear. 10 Small_freshwater_fish loach_presence Initial
34 0.0 0 0 Not sure weatherloach impact on this group may predate on eggs and occur in heavly sedimented environments. 5 Small_freshwater_fish loach_presence Initial
35 0.0 0 2 im less confident about the negative effects of weatherloach, but assume they would predate upon eggs of native fish. most of the target species can co-exist with weaterloach, but best would be 0 weatherloach. 50 Small_freshwater_fish loach_presence Initial
36 5.0 0 20 Can tolerate, but they aren’t good for native fish. 50 Small_freshwater_fish loach_presence Initial
Aggregated 1.7 0 12 NA 32 Small_freshwater_fish loach_presence Aggregated

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