Mortality of post‐settlement abaloneHaliotis iriscaused by conspecific adults and wave exposure

Abstract

Experimental studies of post-settlement abalone (Haliotis iris Martyn) indicate that wave exposure and conspecific adults may be important sources of mortality. In aquarium studies, exposure of post-settlement abalone to grazing by sea urchins (Evechinus chloroticus) and starfish (Patiriella regularis), animals common in the subtidal habitat of H. iris, resulted in similar survival to control treatments (no grazers). However, in the presence of conspecific adults, the survival of post-settlement juveniles was approximately half that of control treatments. The major cause of mortality was evidently pedal smothering by adults. Similar results were obtained in field studies in which survival of recently settled abalone was greater in the absence of conspecific adults. Field studies also revealed that the differences between two bays exposed to contrasting wave action were a significant source of variation in post-settlement mortality. Survival of recruits was greater in the sheltered bay compared with the bay exposed to ocean swells.

Recruitment failure and shifts in community structure following mass mortality limit recovery prospects of black abalone

“…Free space on the substratum is necessary for abalone settlement, and crustose coralline algae (and their associated chemicals and biofilms) are known to induce settlement of abalone larvae (Morse et al 1979, Douros 1985, Day & Branch 2002a. The presence of conspecific individuals, particularly adults, may also be important for settlement as their grazing activities might maintain the cover of crustose coralline algae (Douros 1985) and their mucus on the substratum may act as a positive settlement cue for abalone larvae (Bryan & Qian 1998), but Naylor & McShane (2001) have reported that adult abalone can smother conspecific recruits. The increased cover of tube worms and tube snails documented in this study may be particularly detrimental to recolonization because tube worms have been shown to prey on abalone larvae (Naylor & McShane 1997).…”

New estimates of early post-settlement mortality for intertidal mussels show no relationship with meso-scale coastline topographic features

“…2 d, Ray & Stoner 1995) and abalone species (ca. 25−36% within 3 d, Naylor & McShane 2001). Estimates of total post-settlement mortality in the present study were also substantial (ca.…”

“…Substantial mortality during early post-settlement life has long been suggested and demonstrated across several marine taxa (Connell 1961, Thorson 1966, Gosselin & Qian 1997, Hunt & Scheibling 1997, including reef fish (Searcy & Sponaugle 2001, Doherty et al 2004, mobile invertebrates such as crabs, abalone and other gastropod species (Ray & Stoner 1995, Moksnes et al 1998, Naylor & McShane 2001) and a variety of sessile invertebrates (Hurlbut 1991, Gosselin & Qian 1996, Marshall & Keough 2003. Certainly, juvenile mortality in benthic marine invertebrates is greater than 90% in the majority of studies (Gosselin & Qian 1997), identifying this period as especially important in the life history progression of benthic organisms.…”

“…An additional explanation, however, may lie in patterns of post-settlement mortality. Since juvenile survival can be affected by physiological stresses related to desiccation or emersion (Tan 1975, Iwasaki 1995 and latent effects of larval food availability (Phillips 2002(Phillips , 2004, differences in exogenous 'causal' factors between bay and open coast habitats (such as wave exposure) may well drive patterns of post-settlement mortality (e.g Gosselin & Chia 1995, Naylor & McShane 2001. By investigating postsettlement mortality across multiple bays and open coast sites, we test the hypothesis that postsettlement mortality is lower in bays than on the open coast.…”

“…Much of our knowledge of post-settlement processes and their importance to benthic invertebrate populations comes from the study of barnacles (Foster 1971, Connell 1985, Wethey 1985, Jarrett 2000, Chan & Williams 2003. Some direct estimates of mortality within 2 to 4 d of settlement are available for several other taxa, including ascidians, bryozoans, oysters and gastropods (Davis 1987, Stoner 1990, Ray & Stoner 1995, Gosselin & Qian 1996, Walters & Wethey 1996, Naylor & McShane 2001. For many groups, including bivalves, post-settlement mortality estimates pertain largely to older settlers and recruits (e.g.…”