Studies on southern Australian abalone (genus Haliotis). I. Ecology of five sympatric species

Abstract

Five species of abalone occur along the southern Australian coastline; of these three species, Haliotis laevigata Donovan, Haliotis roei Gray, and Haliotis ruber Leach, are of commercial importance; the other two species are Haliotis cyclobates Peron and Haliotis scalaris Leach. The habitat, movement, feeding behaviour, food, and ecological relationships with predators were studied for each species at three study sites. Each species of abalone occupies a distinctive microhabitat. H. cyclobates lives in calm-water places associated with communities of the seagrass Posidonia australis and the razor shell Pinna dolobrata; H. laevigata lives on open rock adjacent to sand in moderate to rough water localities; H. ruber prefers caves in calm- to rough-water localities; H. roei occurs in narrow crevices in the upper sublittoral on rough-water coasts ; H. scalaris is an under-boulder or crevice-living species. All species are sedentary, but may make local movements in search of food. Several species may occur in a given habitat but there is little microhabitat overlap. The seasonal variation in food eaten by each species is described. All species show preference for red algae and reject most species of brown algae, subsisting predominantly on red algae and seagrasses according to the possibilities of the habitat. H. laevigata feeds mainly on algal drift and H. roei is substantially a grazing species. The other species feed on algal drift or graze opportunistically. Water movement is an important environmental factor affecting the feeding of those species which feed on algal drift. H. laevigata and H. ruber feed best in conditions of moderate water movement but poorly if the water is too calm or too rough. Water movement elicits a characteristic feeding response in these species. The predators of abalone include fish, crabs, molluscs, and starfish; their interaction with abalone is discussed. Crevices, caves, and cavities under boulders provide a refuge in space from predators for H. roei, H. ruber, and H. scalaris and juveniles of other species, which appear to be confined to these places, except for nocturnal feeding excursions, by the activity of their predators. The adults of the different species differ from each other in their dependence on water movement, their preference for open or cryptic sites such as crevices or caves for resting, their size and their methods of feeding. These differences between the species, taken together, ensure that there will be very little overlap between them in the sorts of places that they seek to live in or their behaviour in seeking food; in those cases where food-seeking behaviour is similar, interspecific competition would seem to be negligible because food is abundant. Predation would seem to have been more important than interspecific competition as the selective pressure that established and maintains these differences between the species.

Microhabitat and associated biota of abalone juveniles, Haliotis fulgens and H. corrugata, in Bahía Tortugas, Baja California Sur, Mexico

“…This suggests trophic excursions to this part of the rock, as well as the consumption of macroalgal remains that drift by. The second component consists of the underside of the rocks, which is generally smooth and lacking in macroalgae, as has been reported by other authors (Shepherd, 1973). On this side, in addition to the abalone juveniles, most samples contained bryozoans, sponges, serpulids, and small gastropods, such as Tegula eiseni.…”

“…Lamouroux, 1809, también presentes en la cara superior de las rocas, han sido identificadas en los estómagos de juveniles de ambas especies de Haliotis (Guzmán-del Próo et al, en prensa), lo que sugiere excursiones tróficas hacia esta parte de la roca, junto con el consumo de restos de macroalgas que fluyen a la deriva. El segundo componente de la comunidad se encuentra en la cara inferior de las rocas, generalmente lisa y carente de macroalgas, coincidiendo con observaciones de otros autores (Shepherd, 1973). En esta cara, además de los juveniles de abulón, en la mayoría de las muestras se encontraron briozoarios, esponjas, serpúlidos y pequeños gasterópodos como Tegula eiseni.…”

Population dynamics and fishery management of the paua,Haliotis irisI. Population structure, growth, reproduction, and mortality

“…The average length of 3-year-old H. laevigata from an exposed shore was 30 mm greater than that of those from a sheltered shore, and for H. ruber this difference was 23 mm. H. iris, H. ruber, and H. laevigata extensively use drift algae as food (Poore 1972a;Shepherd 1973), andShepherd (1973) has shown that there is a particular level of water movement associated with the optimal food availability and feeding rates of H. laevigata and of H. ruber. Although no quantitative data are available, wave action within the bays on Banks Peninsula is generally not as strong as at Kaikoura, and so the rate of delivery of food to the Banks Peninsula paua may be limiting growth.…”

Spawning season, fecundity and proximate composition of the gonads of wild-caught blacklip abalone (Haliotis rubra) from Port Fairy waters, south eastern Australia

“…Photoperiod and nutrient supply were considered to be important factors in the reproductive biology of H. cracherodii (Webber and Giese, 1969). In H. laevigata and H. cyclobates, the period of maximum gonad growth coincided with that of an abundant food supply (Shepherd and Law, 1974) and optimal feeding possibilities (Shepherd, 1973). More recently, Counihan et al (2001) suggested that the spawning of H. asinina in the Heron Reef, Australia, was associated with an increase in water temperature (October to April), and that other environmental cues, such as the tidal regime, also appeared to play a role.…”