Direct observations of larval dispersal in the colonial ascidian Podoclavella moluccensis Sluiter: evidence for closed populations

Davis, Andrew R.; Butler, Alan

doi:10.1016/0022-0981(89)90184-6

Cited by 106 publications

(65 citation statements)

References 22 publications

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“…This hypothesis is supported by our finding that larvae exposed to a shadow mimic repeatedly over time showed a gradual reduction in the time spent swimming after each shadow. Interestingly, Davis & Butler (1989) found that larvae of the colonial ascidian Podoclavella mollucecensis initially swam vigorously and continuously, but larvae that swam for the greatest amount of time (6 to 8 min), in the field, occasionally ceased swimming and drifted passively. The negative effects of active swimming may result in a trade-off between the risk of dispersal and advection away from suitable settlement sites (as suggested by Bingham & Young 1991) and the reduction in post-metamorphic performance due to active swimming.…”

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Larval activity levels and delayed metamorphosis affect post-larval performance in the colonial ascidian Diplosoma listerianum

Marshall

Pechenik

Keough

2003

Mar. Ecol. Prog. Ser.

112

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It is becoming widely recognized that extending the larval period of marine invertebrates, especially of species with non-feeding larvae, can affect post-larval performance. As these carry-over effects are presumed to be caused by the depletion of larval energy reserves, we predicted that the level of larval activity would also affect post-larval performance. This prediction was tested with the cosmopolitan colonial ascidian Diplosoma listerianum in field experiments in southern Australia. Diplosoma larvae, brooded in the parent colony, are competent to settle immediately after spawning, and they remain competent to metamorphose for >15 h. Some larvae were induced to metamorphose 0 to 6 h after release, whilst others were induced to swim actively by alternating light and dark periods for up to 3 h prior to metamorphosis. Juvenile colonies were then transplanted to a subtidal field site in Port Phillip Bay and left to grow for up to 3 wk. Extending the larval period and increasing the amount of swimming both produced carry-over effects on post-larval performance. Colonies survived at different rates among experiments, but larval experience did not affect survival rates. Delays in metamorphosis and increased swimming activity did, however, reduce colony growth rates dramatically, resulting in 50% fewer zooids per colony. Moreover, such colonies produced initial zooids with smaller feeding structures, with the width of branchial baskets reduced by 10 to 15%. These differences in branchial basket size persisted and were still apparent in newly budded zooids 3 wk after metamorphosis. Our results suggest that, for D. listerianum, larval maintenance, swimming, and metamorphosis all use energy from a common pool, and increases in the allocation to maintenance or swimming come at the expense of post-larval performance.KEY WORDS: Delayed metamorphosis · Ascidian · Carry-over effects · Larvae · Settlement Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 246: [153][154][155][156][157][158][159][160][161][162] 2003 The main larval experience examined to date has been the simple prolongment of the planktonic period, which, in non-feeding larval stages, most likely results in energy reserves being depleted. Exposure to toxicants may also affect post-metamorphic performance (Pechenik et al. 1998), and, at least for species with lecithotrophic larvae, larval size may also influence post-metamorphic events (Moran & Emlet 2001). In this latter case, it is presumed that larger larvae have more energy reserves available at the time of attachment and metamorphosis. If the planktonic phase competes with metamorphosis for energy reserves, then we predict that variation in larval activity patterns will also affect the energy remaining for metamorphosis by changing rates of energy consumption. The most obvious energy demand on larvae is swimming. Ascidians, with their non-feeding, swimming, tadpole larvae, are strong (although previously untested) candidates for carry over effec...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Larval activity levels and delayed metamorphosis affect post-larval performance in the colonial ascidian Diplosoma listerianum

Marshall

Pechenik

Keough

2003

Mar. Ecol. Prog. Ser.

112

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“…Short term, direct following of larvae is possible for animals such as ascidians, which have large larvae (e.g. Olson & McPherson 1987, Davis & Butler 1989, Young 1990, Bingham & Young 1991). It can also be possible to track particularly dense aggregations of smaller larvae visually (e.g.…”

Section: Discussionmentioning

confidence: 99%

Limited wind-driven dispersal of intertidal mussel larvae: in situ evidence from the plankton and the spread of the invasive species Mytilus galloprovincialis in South Africa

McQuaid

Phillips²

2000

Mar. Ecol. Prog. Ser.

208

145

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Dispersal of intertidal mussel propagules was examined by sampling larvae (0.2 to 0.8 mm) of Perna perna in shallow (10 to 20 m) inshore waters on the south coast of South Africa. Mussels were randomly distributed through the water column with no signs of diel vertical migration. Horizontal distribution was sampled on fine scale grids of plankton stations on 5 occasions. Lines of stations ran offshore and were 300 m apart. Within each line, stations were 10 m apart. On each occasion grids were sampled 3 to 4 times in rapid succession so that each station was sampled at intervals of about 1 h. Distribution was patchy and denser clouds of larvae moved in the same direction and at the same speeds as surface currents. Displacement of passive particles moving with wind-driven currents was estimated from wind data. Over periods of 1 mo estimated total displacement was 118 to 220 km depending on month and year. However, because of frequent changes in wind direction, net displacement for any month was 54 to 164 km to the northeast. These estimates were compared with the rate of spread over 4 yr of an invasive intertidal mussel (Mytilus galloprovincialis) dispersing initially from a single-point source. Spread was estimated as the furthest occurrence of M. galloprovincialis from the parent population. After 4 yr, 90% of individuals sampled were < 5 km from the original population. Yearly increase in range between 1988 (introduction to the area) and 1992 was strongly directional: 55 to 97 km to the northeast and 12 to 29 km to the southwest. The good match with estimates from wind data implies that mussel larvae in this region are dispersed like passive particles and that dispersal direction and ranges can be predicted from hydrographic data. The results strongly suggest that maximum effective dispersal of mussel larvae in this area is relatively limited (<100 km), with the great majority of successful recruits appearing within < 5 km of the parent population.

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“…Laboratory and field studies on ascidians show that planktonic mortality due to 3 predation is variable with values of pre-settlers ranging between 18%, 50% and 87% (Olson and 4 McPherson, 1987;Davis and Butler, 1989;Stoner, 1990). In a coral reef fish, pre-settlement 5 mortality just a few hours before settlement was density-independent and about 61% of larvae 6 died.…”

Section: Larval Predationmentioning

confidence: 99%

Causes of decoupling between larval supply and settlement and consequences for understanding recruitment and population connectivity

Pineda

Porri

Starczak

et al. 2010

Journal of Experimental Marine Biology and Ecology

181

100

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Marine broadcast spawners have two-phase life cycles, with pelagic larvae and benthic adults. 2 Larval supply and settlement link these two phases and are crucial for the persistence of marine 3 populations. Mainly due to the complexity in sampling larval supply accurately, many 4 researchers use settlement as a proxy for larval supply. Larval supply is a constraining variable 5 for settlement because, without larval supply, there is no settlement. Larval supply and 6 settlement may not be well correlated, however, and settlement may not consistently estimate 7 larval supply. 8This paper explores the argument that larval supply (i.e., larval abundance near settlement sites) 9 may not relate linearly to settlement. We review the relationship between larval supply and 10 settlement, from estimates and biases in larval supply sampling, to non-behavioral and 11 behavioral components, including small-scale hydrodynamics, competency, gregarious behavior, 12 intensification of settlement, lunar periodicity, predation and cannibalism. Physical and structural 13 processes coupled with behavior, such as small-scale hydrodynamics and intensification of 14 settlement, sometimes result in under-or overestimation of larval supply, where it is predicted 15 from a linear relationship with settlement. Although settlement is a function of larval supply, 16 spatial and temporal processes interact with larval behavior to distort the relationship between 17 larval supply and settlement, and when these distortions act consistently in time and space, they 18 cause biased estimates of larval supply from settlement data. 19Most of the examples discussed here suggest that behavior is the main source of the decoupling 20 between larval supply and settlement because larval behavior affects the vertical distribution of 21 3 larvae, the response of larvae to hydrodynamics, intensification of settlement, gregariousness, 1 predation and cannibalism. Thus, larval behavior seems to limit broad generalizations on the 2 regulation of settlement by larval supply. Knowledge of the relationship is further hindered by 3 the lack of a well founded theoretical relationship between the two variables. 4The larval supply-settlement transition may have strong general consequences for population 5 connectivity, since larval supply is a result of larval transport, and settlement constrains 6 recruitment. Thus, measuring larval supply and settlement effectively allows more accurate 7 quantification and understanding of larval transport, recruitment and population connectivity. 8 9 4

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Direct observations of larval dispersal in the colonial ascidian Podoclavella moluccensis Sluiter: evidence for closed populations

Cited by 106 publications

References 22 publications

Larval activity levels and delayed metamorphosis affect post-larval performance in the colonial ascidian Diplosoma listerianum

Larval activity levels and delayed metamorphosis affect post-larval performance in the colonial ascidian Diplosoma listerianum

Limited wind-driven dispersal of intertidal mussel larvae: in situ evidence from the plankton and the spread of the invasive species Mytilus galloprovincialis in South Africa

Causes of decoupling between larval supply and settlement and consequences for understanding recruitment and population connectivity

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