Contrasting population dynamics and life histories in two populations of the colonial subtidal ascidian Podoclavella moluccensis

Abstract

Population dynamics and aspects of life history of the colonial ascidian Podoclavella moluccensis Sluiter differed at 2 sltes, a pier and a reef, within St Vincent's Gulf, South Australia. At Edithburgh Pier, colon~es were dense and semelparous annuals. Densities at Port Noarlunga Reef were ca one-seventh of those at Edithburgh and this population was perennial and iteroparous. Population dynamics and fecundity of colonies also differed between sites. Fecundity was higher at Edithburgh, with a greater proportion of each colony brooding and having significantly larger broods. Recruitment at Edithburgh was an order of magnitude higher than at Port Noarlunga. This annual pulse of recru~ts at Edithburgh had a marked impact on size frequency distributions of colonies. Possible reasons for the observed variation in life histories within a species over small spatial scales (60 km) are discussed. The differences between sites identified in this study indicate that assessments of population dynamics and life history attributes of a species should not be restricted to a slngle site.

Ecological and Life History Characteristics of Botryllus schlosseri Tunicata Populations Inhabiting Undersurface Shallow‐Water Stones

“…Wintertime reproductive sterility in B. schlosseri has also been documented in Woods Hole and other Cape Cod tidal pond populations (GROSBERG, 1988). Differences in life history traits between closely situated populations have also been recorded in other colonial tunicates such as Podoclauellu moluccensis from Australia (DAVIS, 1989) and several Botrylloides species (RIN-KEVICH et al, 1993). The above variations are probably due mainly to physicaknvironmental factors.…”

“…The colony surface area (CSA) of botryllid ascidians may be used as an ecological indicator (Russ, 1980(Russ, , 1982CARWILE, 1989;DAVIS, 1989;RINKEVICH e f al., 1993). The measurement of CSA has previously been done directly from photographs (CARWILE, 1989), by tracing the outlines of colonies (MILLAR, 1952;BRUNETTI, 1974;DAVIS, 1989), or by establishing an indirect formula taking into account the number of zooids (RINKEVICH el a/., 1993). To establish the CSA values, we first counted the number of zooids in each of 100 freshly collected colonies.…”

From Tropical to Sub-Tropical: Prolonged Reproductive Activity of the Invasive Ascidian Microcosmus exasperatus in the Eastern Mediterranean

“…This is not surprising, given that ascidians are known to differ in their life-history traits among subpopulations in different seas (Millar, 1952;Davis, 1989;Rocha et al, 1999;Shenkar and Loya, 2008), or even among subpopulations existing in the same area (Rinkevich et al, 1993;Durante and Sebens, 1994). For example, Herdmania momus, a Lessepsian invader in the Levant basin, reproduces in its native range (Red Sea) continuously throughout the year; while in the Mediterranean it has a markedly short seasonal reproduction, taking place twice a year, when the sea temperature matches that of its native range (Shenkar and Loya, 2008).…”

The solitary ascidian Herdmania momus: native (Red Sea) versus non-indigenous (Mediterranean) populations

“…A few studies have demonstrated that ascidians can show differences in life history traits between subpopulations in different seas (Millar 1952(Millar , 1954Davis 1989). Rocha et al (1999) compared the body size of (a) Temperature data at both sites (means ± std).…”