Distribution
(i) Bioregional Data: During the Dragon Search program in South Australia, seadragons have been recorded from 7 of this state’s 8 “bioregions” that have been devised by the Commonwealth’s Interim Marine and Coastal Regionalisation of Australia (IMCRA) program. To August 2000, over 620 sightings have been recorded, 81% of which have come from locations in the Gulf St Vincent Bioregion; 11% from the Eyre Bioregion; 3% from the Coorong Bioregion; and 2% or less from the Eucla, Murat, Spencer Gulf and Otway Bioregions. Around 58% of the total number of seadragons sighted (2061 to date) have come from locations in the Gulf St Vincent Bioregion, 25% from the Eyre Bioregion, and 13% from the Murat Bioregion, the latter two bioregions including “mass sightings” of beachwashed seadragons. No seadragons have been recorded by Dragon Search from the Upper Spencer Gulf Bioregion, and, to date, there has been only one sighting recorded from the Eucla Bioregion, representing the far west coast of South Australia.
 
 

Figure 1b Summarises the bioregional distribution of weedy seadragon sightings recorded during Dragon Search. Note that the exact locations of sightings have not been recorded on the map due to confidentiality reasons. Sightings are denoted by a black line.
 
 

To date, 292 sightings of weedy seadragons and 365 sightings of leafy seadragons have been reported, both figures including 33 sightings in which both leafies and weedies were recorded together at single locations. Seventy-five percent of the weedy sightings and 86% of the leafy sightings have been recorded in the Gulf St Vincent Bioregion. In the Eyre Bioregion, 14% of the total number of weedy sightings, and 8% of leafy sightings have been recorded. The graph below summarises for each bioregion the number of leafy and weedy sightings that have been reported to Dragon Search to date.
 
 

The preponderance of sightings from the Gulf St Vincent (GSV) Bioregion likely reflects the proximity and popularity of dive sites in the area, compared with more remote parts of the state, as well the large number of repeat sightings from several locations in this bioregion (e.g. Rapid Bay, Encounter Bay, north east Kangaroo Island) that have been recorded in the Dragon Search database. The available data cannot be used to determine whether seadragons are relatively more abundant in the GSV bioregion compared with others. In the Murat Bioregion, the small number of sightings (2% of total), compared with the number of seadragons recorded (13%), particularly of dead beachwashed specimens, indicates that there are sites on the west coast (see section below) where seadragons may be relatively abundant, but dive sightings rarely occur in such areas. Furthermore, it is possible that the oceanographic features of parts of the eastern Great Australian Bight may concentrate beachwashed specimens in this area, in conjunction with conditions that may influence sightings of “mass” dead specimens.

(ii) Biounit Scale Data
South Australian marine waters have been divided into “biounits” (Edyvane 1999), to assist coastal marine planning, management, and conservation, including the development of an ecologically representative system of marine protected areas. The biounit classification was derived using coastal marine geomorphological and geological data, physiographic features, small spatial scale oceanographic features, and the distribution of major benthic habitats. Nominal biounit boundaries were set at 30m for the gulfs biounits, and 50m for oceanic biounits (Edyvane 1999).
 
 

The graph below summarises the number of seadragon sightings that have been recorded in each biounit by Dragon Search to August 2000 (including repeat sightings at the same location). Biounits are arranged in approximate order from the westernmost biounit in which seadragons have been recorded (Wahgunyah, towards the WA border), to the easternmost biounit in which seadragons have been recorded (Nene, in the South East of South Australia).
 
 

To August 2000, seadragons have been reported from 24 of South Australia’s 35 biounits. In the southern Fleurieu Peninsula’s Yankalilla Biounit, 31% of all Dragon Search sightings have been recorded, particularly from the Rapid Bay area (at which 72% of the leafy seadragon sightings and 47% of the weedy sightings from that biounit have been recorded). The large number of sightings from popular dive spots, as well as repeat sightings from those specific locations (such as Rapid Bay) has influenced the summary statistics regarding numbers of seadragons sighted per biounit. Therefore, in the Yankalilla Biounit, 26% of the total number of leafy seadragons recorded in the Dragon Search database, and 31% of the total number of weedy seadragons recorded, relate to that biounit.

To date, 17% of Dragon Search sightings have been recorded from sites in the Encounter Biounit, particularly from the eastern end (76% of leafy sightings in that biounit, and 77% of weedy sightings). Of those sightings, 93% of leafy sightings were dive recordings of live seadragons, compared with only 46% of weedy sightings, due to the high number of beachwash sightings of dead weedies.

In the metropolitan area (Clinton Biounit), 16% of all seadragon sightings in South Australia have been recorded. Two thirds of weedy sightings by divers in this biounit have been made on reefs seaward of the metropolitan beach area, and 50% of the leafy seadragon sightings in the Clinton Biounit have come from reefs in the southern end of this biounit. One third of the weedy seadragon sightings in this biounit have been beachwash specimens.

From north-eastern Kangaroo Island (Nepean Biounit), 10% of Dragon Search sightings have been recorded, and 94% of those records represent leafy sightings, mainly of single animals and pairs, reported from one location in that biounit, and including repeat sightings.

To date, 5% of all seadragon sightings have been recorded from sites along eastern Yorke Peninsula (Orontes Biounit), the majority of which comprise leafy sightings from two popular diving locations.

Although only 2% of all sighting have come from the Yanerbie Biounit, these sightings represent 48% of the total number of weedy seadragons and 15% of the total number of leafy seadragons recorded in the Dragon Search database, primarily due to a number of sightings in which large number of dead leafies and weedies were recorded in the beachwash (see section on Beachwashed Seadragons).

Note that relative numbers of seadragons at each location cannot be determined, due to the non-systematic nature of Dragon Search sightings, which are influenced by diver preference regarding choice of dive site; accessibility of dive site; and other factors. Similarly, it is not possible to determine the proportion of sightings per location that are repeat sightings of the same animals or groups of animals.

The relatively small number of records from southern and western areas of the state does not necessarily indicate that seadragons are less abundant at some locations in those areas, compared with more accessible sites. The paucity of sightings in such areas may reflects the smaller number of dives that have taken place in more remote areas compared with popular dive sites in more accessible locations; near large population centres; and/or sites where Dragon Search is more heavily promoted, or known to the diving community.
 

Seadragon Groups
To date, 65% of weedy seadragon dive sightings and 71% of leafy seadragon dive sightings have been of single animals. However, groups of both types of seadragon have been sighted at several locations across the state.

For purposes of data collation, “groups” are nominally described as comprising more than two animals. Groups of between 3 and 12 (and in some cases more) weedy seadragons have been recorded in the following biounits:
(i) Whidbey (from sites around southern Eyre Peninsula bays);
(ii) Clinton (mainly from reefs seaward of the metropolitan beach area);
(iii) Yankalilla (particularly Rapid Bay, but also including reefs off the coast in the northern end of the biounit);
(iv) Cassini (northwestern Kangaroo Island);
(v) Encounter (mostly at sites around the eastern end of the biounit);
(vi) Nene (Carpenters Rocks to Port Macdonnell area).

Leafy groups (3 to 12 or more animals) have been recorded in the following biounits:
(i) Orontes (from several bays and ports along eastern Yorke Peninsula);
(ii) Clinton (from two reefs, seaward of the metropolitan beach area);
(iii) Yankalilla (mainly from Rapid Bay, where sightings of up to 16 animals have been recorded during the summer of 2000, but also including other southern Fleurieu sites);
(iv) Nepean (north eastern Kangaroo Island);
(v) Gambier (from an island in the Gambier Islands Conservation Park);
(vi) Encounter (eastern end of biounit, including older pre-Dragon Search records of 12 leafies sighted together; 20 leafies sighted together; and a more recent record from 1994 of 100 leafies together);
(vii) Nene (Carpenters Rocks to Port Macdonnell area).

In the Encounter Biounit, the leafy groups recorded in the Dragon Search database are mainly older pre-Dragon Search sightings, recorded between 1979 and 1991. However, one record from 1994 of 100 leafies in the eastern end of the biounit was reported. This is the single largest number of live seadragons recorded for the Dragon Search records, from a single site.
 

Brooding Male Seadragons
To date, 16 sightings of brooding male weedy seadragons have been recorded in the Gulf St Vincent Bioregion; 4 from the Eyre Bioregion, and 1 from the Coorong Bioregion. For leafies, brooding males have been recorded in the Gulf St Vincent Bioregion (27 sightings, representing 39 brooding males) and Eyre Bioregion (6 sightings).

To date, these sightings represent 25 brooding male weedy seadragons, and 48 brooding male leafy seadragons. A total of 11 weedy brood male seadragons have been recorded in the Encounter Biounit (eastern end of the biounit); 4 from the Yankalilla Biounit (Rapid Bay area), 3 from the Clinton Biounit (metropolitan area); 2 from the Douglas Biounit (southwestern Eyre Peninsula), and 1 each from three other west coast biounits (Whidbey, Sheringa, Flinders); the Coorong, and north western Kangaroo Island (Cassini Biounit).

Fifty two percent (25 animals) of the recorded number of brooding male leafies have come from the Yankalilla Biounit (mainly Rapid Bay); 9 animals from the Encounter Biounit (eastern end of the biounit); 4 from islands off Port Lincoln area (Jussieu Biounit); 3 from an island in the Gambier Islands Conservation Park (Gambier Biounit); 2 from the Douglas Biounit; 2 from reefs off southern metropolitan beaches (Clinton Biounit); 2 from north western Kangaroo Island (Cassini Biounit), and 1 from northeastern Kangaroo Island (Nepean Biounit).

The majority (80% for leafies, 86% for weedies) of brood male sightings have been of a single male with eggs. However there have been several records of more than one brood male sighted swimming or hovering together in the same location. A group of 3 brooding male weedies was recorded in October 1998 at one of the islands in Encounter Bay. The database also includes an older (pre-Dragon Search) record of a pair each of brooding leafies and brooding weedies sighted together in the Douglas Biounit, in the spring of 1985.  More recently, at Rapid Bay, a group of 5 brooding male leafies, as well as pairs of brooding male leafies, have been recorded (December 1999 and January 2000). From the eastern end of the Encounter Biounit, 6 brooding male leafies have been sighted together in one instance (spring of 1991), and 3 brooding male leafies were recorded together in the summer of 1995 at an island in the Gambier Islands Conservation Park.

Brooding males of both leafy and weedy species were most commonly sited during late spring to summer (Figure 5). For example, at a statewide level, with data pooled for all years, 19 individual sightings of brooding leafy males were made between the months of October and January. The largest number of weedy brood male sightings occurred between October and November (13 sightings). Little can be inferred from the relatively low number of weedy brood male sightings in December, due to the unstandardised and opportunistic nature of Dragon Search record collection. No brooding males of either species were observed during March to July in any year. Brood males of both species have been observed at sites in Gulf St Vincent, from September to January. From Encounter Bay sites, leafy brood males have been recorded between October to December, and weedy brood males from August to February.
 
 

Although most dives were undertaken during the warmer months, 33 sightings each of both leafies and weedies (12% and 12.5% respectively of all sightings to November 1999) occurred during the winter months (June to August). To date, no live brooding male seadragons have been recorded by Dragon Searchers during this time. The Dragon Search records support available evidence that the reproductive period for these two species occurs during late spring to summer.
 

Juvenile Seadragons
Weedy and leafy groups of adults and juveniles swimming or hovering together have been recorded in the Yankalilla Biounit at Rapid Bay (e.g. 4 adult and 12 juvenile weedies; 6 adult and 4 juvenile leafies). Another large "family" group of leafies (of 8 adults and 5 juveniles) was recorded at a site in the southern region of the Orontes Biounit (Yorke Peninsula) in 1994.

At Rapid Bay, Dragon Search volunteers have apparently recorded juvenile leafies from November to March during the past 5 years, although single sightings have also been recorded in May and August. There have been a number of sightings of juvenile leafies in the southern part of the Orontes Biounit, and other locations off Yorke Peninsula. Juvenile weedies have been recorded at Rapid Bay in January, March, April, June and August. Juvenile weedies and leafies have also been recorded during the Dragon Search program at other southern Gulf St Vincent locations and at metropolitan locations.

There appears to be no seasonal pattern to the sighting of juveniles. To date, juvenile weedies have been sighted throughout the year, except May, July and October. Juvenile leafies have apparently been sighted in all months of the year, except June, July and September. A size of less than 20cm was stated on the Dragon Search Seadragon Sighting Form as a guide to identifying juvenile seadragons. However, some of the records may be of small adults or young adults, and some might include misjudgments of size by recorders, which might explain the lack of seasonality of the juvenile sightings. Due to the opportunistic nature of the Dragon Search sightings, and the lack of standardisation between months regarding the distribution and frequency of recordings, available data cannot be used to determine in which season juveniles are more abundant.
 
 

"Beachwashed" Seadragons
To August 2000, beachwashed seadragons have been recorded from approximately 62 different areas along the South Australian coastline, comprising 157 sightings, and a total of 988 specimens. In the Encounter Biounit, 25% of the weedy beachwash sightings from S.A. have been recorded, with 16% of weedy beachwash sightings from the metropolitan Clinton Biounit, 16% from the Yankalilla Biounit (southern Fleurieu Peninsula); 11% from the Gantheaume Biounit (southern Kangaroo Island), and 6% from the Coorong Biounit.  For leafies, 24% of beachwash sightings were recorded in the metropolitan Clinton Biounit; 12% each from the Yankalilla and Encounter Biounits; and 7% each from Yanerbie Biounit (west coast); Douglas and Whidbey Biounits (both southwestern Eyre Peninsula); Gantheaume (southern Kangaroo Island); and Coorong Biounits.

In the Yankalilla Biounit, beachwash specimens have been recorded from four beaches. To date, the only recording of a large number of dead seadragons sighted in one location within the Yankalilla Biounit, has been from a beach at the northern end of the biounit (30 dead weedies). In the Encounter Biounit, 53% of all weedy seadragon sightings from that biounit have been dead beachwashed specimens. Sightings of large numbers of dead weedies (e.g. 15 animals; 40 animals) were recorded in the Encounter Biounit during spring to summer in 1997 and 1998. Along southern Kangaroo Island (Gantheaume Biounit), 3% of all seadragon sightings have been recorded, primarily beachwashed specimens from the two bays, and sites on the south eastern side of Kangaroo Island. A “mass sighting” of 29 dead weedies was recorded from southern Kangaroo Island (Gantheaume Biounit) in the summer of 1999.  Other records of beachwashed specimens are known from southern Kangaroo Island, but these records are not available for collation in the Dragon Search database.

Sightings of “mass” beachwashed leafy and weedy seadragons have been recorded in the Yanerbie Biounit on the west coast, particularly from the Anxious Bay and Corvisart Bay areas, where up to 250 beachwashed weedy specimens have been recorded in one instance. Four of these “mass sightings” occurred during the period in which one of the two “pilchard kill” events* from the late 1990s in South Australia was recorded on the west coast. It is possible that some of the conditions that precipitate mass fish kills, such as oxygen depletion of near surface waters following algal blooms, might also be partly responsible for the mass sightings of dead seadragons observed. Other sightings of large numbers of dead seadragons (e.g. up to 100 leafies and weedies) were recorded in the Yanerbie Biounit during the late 1980s and early 1990s.

*Large numbers of dead seadragons were recorded during the "pilchard kill" events of mid 1996 and the summer of 1998/99. Beachwashed seadragons were found amongst dead pilchards over most of the coastal area of South Australia, from Yalata on the far west coast to as far east as Goolwa

Forty-six percent of all sightings occurred during the summer months, 21% during autumn, 11% during winter, and 22% during the spring months. To November 1999, there had been 72 sightings of "freshly dead" seadragons, and 46% of those sightings occurred during the months of January to March
 

Sighting Details
Unsurprisingly, more records of both species were made during summer (38% of weedy sightings and 46% of leafy sightings), when diving conditions are more amenable, compared with other seasons. For both species, 12% to 13% of sightings were made during winter, and between 20% and 25% of sightings occurred during spring and autumn. Neither relative frequency nor seasonal abundance of seadragons per sighting location can be meaningfully discussed due to the non-standardised nature of the recording, which are affected by a number of factors. These include (i) uneven distribution of recordings over space and time; (ii) individual preferences in the locations and seasons in which recorders chose to dive or beach-walk, (iii) weather and/or sea conditions, and (iv) other opportunistic and/or uncontrollable aspects of the recordings.

To date, 82% of leafy seadragon sightings have been recorded by SCUBA divers, 15% have been records of dead leafies sighted by beachcombers, and 1% each of sightings have been recorded by snorkellers and fishers/boaters. The number of SCUBA records of live seadragons is lower for weedies (58%), reflecting the relatively high number of beach-washed records of dead animals (40%), particularly during the pilchard kill event of summer 1998/1999 (see below).
 

Habitat Preference
To date, habitat type has been specified for 96 weedy sightings and 109 leafy sightings. Although there appears to be some lack of standardisation between divers in recording habitat details, notable results to date include:
- the low incidence of seadragon sightings on bare sand and/or rubble (2% of weedy sightings and 3% of leafy sightings), which might reflect less food availability in waters over bare substrate, and/or seadragons' habitat preference for vegetation as a means of camouflage;
- the similar incidence of sightings over seagrass, for both weedies and leafies (27% and 30% respectively of sightings);
- the higher incidence (51% for weedies and 47% for leafies) of sightings over reef (including the two categories: macroalgal-dominated reef and reef of unspecified cover)
- records of both leafy and weedy seadragons observed feeding over seagrass beds and macroalgal reefs.

Divers are more likely to dive over seagrass beds and reefs, rather than bare substrate, and therefore the low incidence of sightings in the latter habitat cannot be used as conclusive evidence of habitat preference for vegetated sites.  However, we can infer from these data that both leafies and weedies utilise both macroalgal-dominated reef and seagrass habitats.
 

Behaviour
To November 1999, 352 weedies had been recorded during Dragon Search and related sightings. Of these animals sighted, 23% have been recorded as hovering, 10% were recorded as swimming, 9% feeding, and 7% were recorded as being engaged in other behaviours/activities. There was no recording of behaviour for 51% of weedies sighted.  To November 1999, 473 leafy seadragons had been sighted, including one unusual record of a group of 100 leafies sighted together. Hovering was listed as the observed behaviour for 46% percent of the leafy seadragons sighted.  Four percent of leafies sighted were feeding, 3 % were swimming, and 2% were listed as being engaged in other behaviours/activities. Behaviour was not recorded for 45% of the leafies sighted.
 

Other Data (Depth of Sightings; Water Temperature)
Figure 7 displays the range of depth recordings per month, for leafies and weedies, to November 1999. Figure 7 indicates that the maximum sighting depth per month is, on average, higher for weedies than for leafies.  However, little else can be inferred about seasonal depth variations in seadragon distribution from these data. Several reasons include the fact that

(i) the number of sightings recorded per month is opportunistic, according to diver preferences; therefore, the number of records is higher in warmer months (pleasant diving conditions), and winter sightings are underrepresented;
(ii)  the survey was not standardised: i.e. seadragons were not searched for, at specific depths, in every month; and
(iii) the uneven numbers of records between months influences the depth range of the sightings that are recorded in each month (for some months, seadragons may be found at other depths that have not recorded here due to the small number of records available for those months).

Other influences include possible depth gauge inaccuracies on divers' watches, and the fact that in some parts of the state, sighting depths are influenced by the depth of features at preferred dive locations, such as depth of seagrass patch, reef or "bommie". That is, sea dragons may be found at other depths in the vicinity, but such depths were not surveyed because they did not contain the feature of dive interest.

Similar caveats apply to the interpretation of temperature recorded during seadragon sightings, particularly due to the prevalence of summer diving relative to other times of the year. However, one notable result from these data is the recorded temperature range for sightings, which, to date, has ranged from 10^oC to 24^oC for both species.
 

Reference
Edyvane, K. S. (1999). Conserving Marine Biodiversity in South Australia - Part 2 - Identification of areas of high conservation value in South Australia. (SARDI Research Report Series No. 39).
 

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