Weedy Seadragon Phyllopteryx Taeniolatus Research Articles

Demographics and vulnerability of a unique Australian fish, the weedy seadragon Phyllopteryx taeniolatus

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 422:253-264 (2011) - DOI: https://doi.org/10.3354/meps08920 Demographics and vulnerability of a unique Australian fish, the weedy seadragon Phyllopteryx taeniolatus Jaime Sanchez-Camara1, Keith Martin-Smith2, David J. Booth3, Juan Fritschi1, Xavier Turon4,* 1Aquadec Aquariums S.L., 18600 Motril, Granada, Spain 2Australian Antarctic Division, Australian Government Department of Environment, Water, Heritage and the Arts, Kingston, Tasmania 7050, Australia 3Department of Environmental Sciences, University of Technology, Sydney, PO Box 123, Broadway, Sydney, New South Wales 2007, Australia 4Department of Marine Ecology, Center for Advanced Studies of Blanes (CEAB, CSIC), 17300 Blanes (Girona), Spain *Corresponding author. Email: xturon@ceab.csic.es ABSTRACT: The weedy seadragon Phyllopteryx taeniolatus is a vulnerable and endemic Australian fish and also an icon and flagship species for marine conservation. However, little is known about its population dynamics, which hinders the establishment of conservation policies. We have previously demonstrated seadragons to be highly site-attached, so we estimated population densities, growth and survival of weedy seadragons using mark-recapture techniques at 5 sites in New South Wales (NSW, 34°S) and Tasmania (TAS, 43°S), near the northern and southeastern limit of distribution for the species, over a 7 yr period. Population densities varied from ca. 10 to 70 seadragons ha–1 depending on site and year. There was a significant decline in the number of weedy seadragon sightings per unit area searched in 2 out of 3 study sites near Sydney, NSW, from 2001 to 2007. There was also a decline at one of the 2 sites surveyed in the lower Derwent Estuary, TAS, in 2009 compared to 2003 and 2004. Survival rates at NSW sites ranged from 0.62 to 0.65 yr–1 and were higher at TAS sites where they ranged from 0.71 to 0.77 yr–1. Birth occurred approximately 3 mo later and seadragons exhibited significant slower growth in TAS (maximum adult size × growth rate parameter, L∞ × k = 31.02) compared to NSW (L∞ × k = 55.15). This study is the first population assessment of seadragons over ecologically relevant spatial and temporal scales, and shows differences in the dynamics of populations at different latitudes. It also shows declines in some populations at widely separated sites. Determining whether these declines are natural interannual fluctuations or whether they are caused by environmental or habitat changes must be a priority for conservation. KEY WORDS: Mark-recapture analyses · Conservation · Growth · Survival rate · Population dynamics · Endemic Australian fish Full text in pdf format PreviousNextCite this article as: Sanchez-Camara J, Martin-Smith K, Booth DJ, Fritschi J, Turon X (2011) Demographics and vulnerability of a unique Australian fish, the weedy seadragon Phyllopteryx taeniolatus. Mar Ecol Prog Ser 422:253-264. https://doi.org/10.3354/meps08920 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 422. Online publication date: January 31, 2011 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2011 Inter-Research.

Density, habitat use and behaviour of the weedy seadragon Phyllopteryx taeniolatus (Teleostei:Syngnathidae) around Sydney, New South Wales, Australia

The vulnerability of marine fish species, particularly those inhabiting coastal waters, is an increasingly important issue in marine conservation. Although the weedy seadragon Phyllopteryx taeniolatus (Lacepede, 1804), a syngnathid fish endemic to southern Australia, is legally protected in New South Wales, there are no studies on population density, habitat use and behaviour to support this protection. We investigated the abundance, sex ratios and distribution of the weedy seadragon at three sites near Sydney, Australia. The distribution, density and sex ratios of seadragons were temporally stable, suggesting no large-scale seasonal migrations. Estimated population densities varied among sites from 10 individuals per ha to 65 individuals per ha, with sex ratios close to 1 : 1. Survival rates from one encounter to the next (approximately weekly) were high, being slightly lower for males (0.985 ± 0.006, mean ± se) and females (0.987 ± 0.005) compared with juveniles (1.000 ± 0.000). All size classes and both sexes were most common near the border of kelp and sand except when exhibiting hiding behaviour, when they were more often found in kelp beds. Kelp beds were the least-used habitat when feeding. Pregnant males tended to hide more often than other groups and therefore were more frequently found in kelp and kelp patches. Seadragons tended to be solitary, although pairing and grouping behaviour was also observed. Results of the present study show that weedy seadragons are resident in the same area throughout the year and have a strong affinity with heavily weeded rock and/or sand habitat. It is therefore recommended that the current species-based protection laws be used in concert with habitat-protection zones as a necessary measure to ensure the conservation of weedy seadragon populations.

Reproductive cycle and growth of Phyllopteryx taeniolatus

In this study, 36 males, 33 females and 15 juveniles of the common or weedy seadragon Phyllopteryx taeniolatus, a syngnathid fish endemic to the waters of southern Australia, were identified using visual implant fluorescent elastomer tags and pattern of appendages and their reproductive cycle and growth was studied from May 2001 to June 2002. Brooding males were present for a period of >6 months, from June–July to early‐January. The percentage of males that were pregnant in the studied areas peaked in November–December, near the end of the breeding season. Two pregnancies were reported for some males. Ten recruits were identified from November to June. Growth rates for young‐of‐the‐year, young of the previous year, males and females were measured. The von Bertalanffy growth constant K was estimated at 0·098 month−1.

Movement, Home Range and Site Fidelity of the Weedy Seadragon Phyllopteryx taeniolatus (Teleostei: Syngnathidae)

We measured for the first time movement, home range and site fidelity of the protected and endemic Australian fish weedy seadragon Phyllopteryx taeniolatus. Ninety-two individuals were identified using visual implant fluorescent elastomer and studied over a one-year period. Identified animals remained at the same site over the year within limited home ranges. These home ranges and the movement patterns recorded were independent of sex although movement to shallow sheltered waters to hatch the young was observed at the end of the breeding season for some pregnant males. The site fidelity and restricted home range of the weedy seadragon, as well as the reproduction-related movement have implications for effective management of this protected species.

Scuticociliata infection in the weedy sea dragon Phyllopteryx taeniolatus

The weedy sea dragon Phyllopteryx taeniolatus at an aquarium in Kanagawa Prefecture were found infected by protozoan ciliate, 2001. The infected fish in particular, showed sloughing of the epidermis. Fish with intense infections showed sloughing of the dorsal fin, depigmentation of skin, anal distension and accumulation of ascitic fluid in the body cavity. In biopsies, ciliates were detected only in fresh mounts of abdominal dropsy and in the mucus on the body surface. Histopathological studies revealed ciliates mainly infected the dermis, and induced extensive detachment of the epidermis from the skin. Based on the arrangement and shape of the buccal structure and the number of somatic ciliature, ciliates isolated from the fishes belonged to the order Scuticociliatida. We discuss the major factors that bring about the death of weedy sea dragons.