Ontogenetic and sex‐based differences in habitat preferences and site fidelity of White's seahorse Hippocampus whitei

Abstract

The aim of this study was to determine and compare habitat preferences for male and female adult and juvenile White's seahorse Hippocampus whitei and assess their movements and site fidelity over 4 years. Data were collected from three sites along 1.5 km of estuarine shoreline in Port Stephens, New South Wales, Australia, from 2006 to 2009 using H. whitei that had been tagged with visible implant fluorescent elastomer. Relative availability of 12 habitats and habitat preferences of H. whitei was determined, based on the habitat that H. whitei used as a holdfast. Hippocampus whitei occurred in nine different habitats; adults preferred sponge and soft coral Dendronephthya australis habitats with no difference between male and female habitat preferences whilst juveniles preferred gorgonian Euplexaura sp. habitat. There was a significant preference by adults for D. australis colonies with height >40 cm and avoidance of colonies <20 cm. Neither adults nor juveniles used sand or the seagrasses Zostera muelleri subsp. capricorni and Halophila ovalis. Hippocampus whitei showed cryptic behaviour with c. 50% of adult sightings cryptic and c. 75% for juveniles with crypsis occurring predominantly in Sargassum sp. for adults and Euplexaura sp. habitat for juveniles. Within sites, females moved significantly longer distances (maximum of 70 m) than males (maximum of 38 m) over 20 months. Strong site fidelity was displayed by H. whitei with males persisting at the same site for up to 56 months and females for 49 months and no H. whitei moved between sites. The longest period that an H. whitei was recorded on the same holdfast was 17 months for a male and 10 months for a female. As this species displays strong site fidelity, specific habitat preferences and has a limited distribution, future management needs to minimize the risk of habitat disturbance as loss of key habitats could have a negative effect on species abundance and distribution.

Monthly population density and structure patterns of an endangered seahorse Hippocampus capensis: a comparison between natural and artificial habitats

“…How seahorses adapt to habitat alterations and additions, if at all, is an important characteristic that must be understood to ensure their successful future conservation (Vincent et al ., ). Habitat use is also an important aspect in seahorse population assessments (Curtis et al ., ), because seahorse abundance, population density and distribution change across different habitat types (Curtis & Vincent, ; Harasti et al ., ; Otero‐Ferrer et al ., ). Habitat‐use data are also helpful to understand possible reasons for seahorse population variability and many studies have focussed on population density and distribution within different habitat types (Curtis & Vincent, ; Gristina et al ., ; Otero‐Ferrer et al ., ).…”

Fidelidad al sitio y rango de hogar del caballito de mar narizón <i>Hippocampus reidi</i> (Teleostei: Syngnathidae) en la dársena de Varadero, noroeste de Cuba

“…Moreau & Vincent (2004) también observaron que en las costas de Victoria, Australia, las hembras de H. breviceps presentaron rangos de movilidad más amplios en comparación con los machos. Resultados similares fueron encontrados por Harasti et al (2014) en la región australiana de Nueva Gales del Sur para H. whitei. Aunque nuestros resultados no muestran diferencias entre los sexos en este sentido, Vincent et al (2005) han planteado la hipóte-sis de que los machos de caballitos de mar podrían presentar una capacidad de desplazamiento más limitada debido a la necesidad de conservar energía en la etapa reproductiva, ya que son ellos los responsables de portar los embriones en su bolsa.…”

“…Estos conocimientos resultan necesarios para la creación de estrategias de manejo efectivas y programas de conservación in situ (Harasti et al 2014). Para ello, se requiere de la identificación particular de los ejemplares, principalmente mediante el marcaje.…”

Southern range extensions for twelve heterobranch sea slugs (Gastropoda: Heterobranchia) on the eastern coast of Australia

“…'Seahorse Gardens' is 900 m east of the 'Pipeline' and supports octocoral colonies situated in sandy substrate with sponges located in deeper areas (Harasti et al, 2014). 'Fly Point' lies to the east of 'Seahorse Gardens' within a sanctuary (no take) zone that has been protected since 1983.…”

“…While many habitats are similar to those at 'Pipeline' , there are extensive areas of large sponges in the deeper sections (to 24 m) (Coleman and Marsh 1997). 'Little Beach' is 450 m east of 'Fly Point' and comprises sandy substrate interspersed with seagrasses, sponges and gorgonians (Harasti et al, 2014).…”