Importance of algal turf, grazers, and spatial variability in the recruitment of a subtidal colonial invertebrate

Abstract

ABSTRACT. Factors affecting the recruitment of a colonial ascidian, Pseudodistoma novaezelandiae (Brewin), were investigated in a rocky subtidal habitat at Leigh, New Zealand. The presence of coralline algal turf enhanced recruitment both in natural conditions, when standardized against adult abundance, and also in an experiment in which algal turf was removed. Removal of the large gastropod Cookia sulcata (Gmelin) and the echinoid Evechinus chloroticus (Val.) had no effect on recruitment.Recruits were aggregated on 2 spatial scales, tens of metres and -1 m; the degree of aggregation changed over the recruitment season, and varied according to the presence or absence of algal turf. Recruits occurred only in the vicinity of the highly localized populations of adult ascidians, separated by 100 m or more. Within these populahons, however, on a scale of tens of metres, numbers of recruits were not correlated with adult abundance.

Recruitment patterns in an intertidal species with low dispersal ability: the reef-building Dendropoma cristatum (Biondi, 1859) (Mollusca: Gastropoda)

“…The adults have a shell size of 3-6 mm when they are 1 year old, and they are often covered by an encrusting red algae (Calvo et al 1998;Milazzo et al 2014). The number of recruits was standardised against the surface and adult abundance because of the low dispersal ability of the crawling larvae, and also because the greater the number of adults the greater can be the number of recruits (Stocker & Bergquist 1987).…”

Sampling Larval Fish Populations: Choice of Sample Number and Size

“…Acceptable levels of precision will be specific to the question being asked. Many authors (Standen and Latter 1977;McElhone 1978;Downing 1979;Gilyarov et al 1979;Jones and Francis 1982;Way and Wissing 1982;Drake 1983;Downing and Cyr 1985;Morin 1985Morin , 1987Pont 1986;Downing et al 1987;France 1987;Stocker and Bergquist 1987;Vezina 1988;Pace et al 1991) have demonstrated that the sampling variance for sets of replicate samples of benthos, phytoplankton, and zooplankton from streams, lakes, and marine environments varies consistently as s 2 = *•*>;…”

Biological Heterogeneity in Aquatic Ecosystems

“…Departures from m = s2 are most acute when large numbers of organisms per sample are encoun tered in samples. Intersample s2 therefore suggests that aquatic popula- Stocker and Bergquist (1987);16, Downing et al (1987);17, 20, Frontier (1972); 21, Jones Downing and Rath (1988); 24, Downing and Anderson (1985); 25, France (1988). Table 9.2.…”