Haliotis

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.

Abstract: To evaluate the general utility of sequences of the nuclear rDNA internal transcribed spacer (ITS) regions for phylogenetic analyses of animal species groups and their broader relationships, sequences were obtained for 19 species of the genus Haliotis plus a keyhole limpet and a more distantly related gastropod, the Chilean abalone. Three subclades of Haliotis species appear consistently, each encompassing little variation. They are (A) the North Pacific species, (B) the European species, and (C) the Australia species. The one Caribbean species examined clearly groups with the North Pacific clade, not the European clade. H. midae (South Africa) and H. diversicolor supertexta (Taiwan) both diverge basal to the European and Australian species groups in the phylogenetic trees. Sequence comparisons showed that one species of Haliotis, H. iris from New Zealand, is quite distant from the remaining Haliotis species, almost as much as the more obvious outgroup, the keyhole limpet, an observation common to other DNA sequence analyses of these taxa. Using the rate of nucleotide change calculated from the sister Caribbean-Pacific pair, the length of the H. iris long branch is compatible with the suggestion that its ancestry became isolated on New Zealand at Gondwandan breakup. Use of ITS permits a totally independent estimate of the phylogenetic relationships, yet branching order was very similar to that established using other DNA regions studied previously, including those under strong positive selection. Knowledge of the RNA transcript secondary structure is particularly useful in the optimal alignment of more distantly related taxa. The RNA transcript secondary structure of Haliotis ITS2 shows conservation of features found also in ITS2 of angiosperms and algal taxa. Since ITS, particularly ITS2, is not saturated with nucleotide changes even at the family level, it should be useful for phylogenetic reconstruction of animal groups, not just at the species and genus levels but perhaps also for families and above.

Abstract: The most fragile skeletons produced by benthic marine calcifiers are those that larvae and juveniles make to support their bodies. Ocean warming, acidification, decreased carbonate saturation and their interactive effects are likely to impair skeletogenesis. Failure to produce skeleton in a changing ocean has negative implications for a diversity of marine species. We examined the interactive effects of warming and acidification on an abalone (Haliotis coccoradiata) and a sea urchin (Heliocidaris erythrogramma) reared from fertilization in temperature and pH/pCO2 treatments in a climatically and regionally relevant setting. Exposureofectodermal(abalone)andmesodermal(echinoid)calcifyingsystemstowarming(þ28Cto 48C) and acidification (pH 7.6‐7.8) resulted in unshelled larvae and abnormal juveniles. Haliotis development was most sensitive with no interaction between stressors. For Heliocidaris, the percentage of normal juveniles decreased in response to both stressors, although a þ28C warming diminished the negative effect of low pH. The number of spines produced decreased with increasing acidification/pCO2, and the interactive effect between stressors indicated that a þ28C warming reduced the negative effects of low pH. At þ48C, the developmental thermal tolerance was breached. Our results show that projected near-future climate change will have deleterious effects on development with differences in vulnerability in the two species.