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Home , Recruitment (biology), Reproduction

5. Reproduction and Recruitment  Sexual vs

 Reproductive effort

 Developmental types

 Trends in reproductive

 What is recruitment?

 Factors affecting recruitment

 Process of larval selection

Dr Laura J. Grange ([email protected]) 18th April 2011 Reading: Levinton, Chapter 5, “Reproduction, Dispersal and Migration” General Development of Benthic

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Fertilization FREE LARVAE

Reproduction Metamorphosis

ATTACHED JUVENILE

ATTACHED Growth  Gonochorism  Single sexes  Hermaphroditism  Dual sexuality  Simultaneous, Sequential Crepidula fornicata

 Common Slipper Limpet

 Invasive  Europe  Pacific Northwest  Japan

 Form “Stacks”

 Sequential  Base =  Larger!  Top = Male Sexual Reproduction  Gonochorism  Single sexes  Hermaphroditism  Dual sexuality  Simultaneous, Sequential, Cyclical

 Semelparous  Single reproductive effort  E.g., nudibranchs, polychaetes  Iteroparous  Multiple reproductive events  E.g., Corals, seastars Asexual Reproduction

 Produces genetically identical to parent

 Does not involve fertilization

 Only one parent involved

 Some primarily (but not solely) reproduce asexually  Prokaryotes ()

 Some swing both ways!  Corals, fungi Asexual Reproduction Reproductive Effort  It takes to reproduce  Reproductive Effort

 Metabolic energy spent reproducing…  Searching for mates  Copulation  formation  = how many off spring you produce  Fertilization mechanisms  Brood protection & parental care General Development of Benthic Invertebrates

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Reproduction

ATTACHED ADULTS Development Types

 Different types of larvae produced in benthic  Planktotrophic  Lecithotrophic  Direct Development

 Suitable for different strategies  Dispersing long distances  Surviving predators  Settling fast Development Types

 Planktotrophy  Planktonic free living larvae  No parental care  Feeds in the plankton – phyto/zoo/bacteria//DOM  Special ciliary bands  High fecundity  In plankton – ~hrs to months  Can travel V. long distances!  High dispersal potential  Delayed metamorphosis can be possible

Thorson, 1961; Jaekle & Manahan, 1989; Strathmann & Strathmann, 2007 Development Types  Lecithotrophy  Planktonic free living larvae

 Do not feed in the plankton  In plankton – ~hrs to days

 Can also travel, but limited by food source  Medium fecundity

 Large yolky  Evolutionary advantage

 Correlation between lower yet still relatively high dispersal capabilities Larvae Development Types

 Direct Development

 Brooding or egg masses

 No free larvae

 High parental care

 Produces benthic juvenile

 Lower fecundity

 Little dispersal

 Esp in sessile organisms Development Types

 Mixed Development  Some brooding then a planktonic stage  Parental protection & higher dispersal  Best of both worlds??

Gallardo, 1977; Caswell, 1981 Development Time

More Reproductive Effort 500

Direct Higher chance K of survival

Egg Lecithotrophic Diameter (microns)

Planktotrophic r 0 0 50 Embryonic development time (days)

Todd and Doyle, 1981; Barnes & Hughes, 1998 r/K Selection Theory

 r Selected  K Selected  Reproduce quickly  Extensive parental care  High fecundity  Low fecundity  Early maturation to  Long maturation time  Short span  Long life span  Small body size  Larger body size  Unstable Environments  Stable Environments  Suitable for life in  Suitable for life in stable, that change over small unchanging environments time scales  E.g. Corals, deep-sea  E.g. Barnacles, organisms polychaetes Timing of Reproduction

 When is a good time to reproduce?  Energy  Fixed amount of energy to an  Growth & Reproduction  Food to benthos can be seasonal  Energy Allocation  To  Use food pulses to start reproduction  To Larvae  Use food pulses to feed larvae Timing of Reproduction

 Eckelbarger & Watling (1995)  1 – Fast egg producers (immediate response to bloom)  2 – Slow egg producers ( when conditions favor larvae)  3 – Slow egg producers (use bloom to start repro)  4 – No relationship to bloom Trends in reproductive ecology  Low Latitudes   Planktonic development   Planktotrophy

 High Latitudes   Direct development   Lecithotrophy

 Deep Sea   Direct development

MANY EXCEPTIONS TO ALL OF THESE Thorson, 1950; Young, 1994; Grassle, 1994; Pearse, 1994; Rex & Waren, 1982 Settlement and Recruitment

Dispersive Larvae Broadcast Selement spawning Recruitment Brooding

Sessile Adult

Direct Development Settlement/ Recruitment?

 Settlement

 Attachment to benthos, metamorphosis into adults

 Site critical for sessile organisms

 Availability of larvae, settlement cues, hydrodynamic factors, larval behavior – all affect settlement

 Recruitment

 Number of organisms that settle and survive in a

 Operationally defined, e.g., it occurs when an organism is first detectable on a settling plate or in a colonization tray.

 Incorporates “post-settlement mortality” Why study recruitment?  Important process in determining

 Cannot predict recruitment from reproduction  Just because you have high fecundity doesn’t mean you have high recruitment  Post-Settlement Mortality  How can you predict recruitment?

 Two long standing hypothesis  Supply Side Ecology  limited by factors affecting adults  Larval Habitat Selection  Populations limited by habitat Lewin (1986), Young (1987) Supply Side Ecology

 Space will not be occupied unless propagules get to it

 Processes causing variation in arrival of recruits  Production of larvae  Fertilization  Dispersal  Transport, period of dispersal, mortality  Oceanographic conditions  Larval mortality  Larval behavior  Settlement Larval Habitat Selection

 Much of early motivation for studying recruitment

 Directed towards settlement

 Main Issues  Do larvae actively select habitat?  If so, how?

 Alternatives to Active Selection  Passive  Hydrodynamic dispersal and sorting  Larvae and substrate have related characteristics (eg Stickiness) Larval Habitat Selection

 3 Stages of Settlement

 Stage 1 - Getting to/staying in vicinity of suitable habitat

 Stage 2 - Getting to the bottom

 Stage 3 - Staying on the bottom

 Active processes could be useful in all these stages Conclusions

 Many life histories amongst invertebrates  Though there are trends, these are not rules

 Though direct development is more evolutionary evolved, many advantages to pelagic development

 Cannot infer recruitment from settlement  Modified by post-settlement mortality

 Larval arrival/retention often influenced by larval behavior

 Interactions between benthic recruitment and water column processes in the field are poorly known References

 Barnes, R.S.K. & Hughes, R.N. 1999. An introduction to marine ecology. Blackwell Science, Oxford.

 Caswell, H. 1981. The of “mixed” life histories in marine invertebrates and elsewhere. American Naturalist, 117: 529-536.

 Gallardo, C.S. 1977. Two modes of development in the morphospecies Crepidula dilatata (Gastropoda: Calyptraeidae) from Southern Chile. Marine , 39: 241-251.

 Grassle, J.F. 1994. Ecological patterns in the deep-sea benthos: how are they related to reproduction, larval biology and recruitment. In: Young, C.M & Eckelbarger, K.J. (eds) Reproduction, larval biology and recruitment of the deep- sea benthos. Columbia University Press, New York. pp 306-314.

 Jaeckle, W.B. & Manahan, D.T. 1989. Feeding by a “non-feeding” larva: uptake of dissolved amino acids from seawater by lecithotrophic larvae of the gastropod Haliotis rufescens. , 103: 87-94.

 Levinton, J.S. 2001. Part II. Marine Organisms: and Environment. 5. Reproduction, dispersal and migration. In: Marine Biology. Oxford University Press, Oxford. References contd

 Lewin, R. 1986. Supply – side ecology. Science, 234 (4772), 25-27.

 Strathmann, M.F. & Strathmann, R.R. 2007. An extraordinarly long larval duration of 4.5 years from hatching to metamorphosis for teleplanic veligers of Fusitriton oregonensis.

 Thorson, G. 1950. Reproductive and larval ecology of marine invertebrates. Biological Review, 25: 1-45.

 Thorson, G. 1961. Length of pelagic larval life in marine bottom invertebrates as related to larval transport by ocean currents. In: Sears, M. (ed) Oceanography. American Association of Advanced Science (publ No 67), Washington D.C. pp 455-474

 Pearse, J.S. 1994. Cold-water echinoderms break “Thorson’s rule”. In: Young, C.M. & Eckelbarger, J.K. (eds) Reproduction, larval biology and recruitment in the deep- sea benthos. Columbia University Press, New York. pp 26-43.

 Rex, M.A. & Waren, A. 1982. Planktotrophic development in deep-sea prosobranch snails from western North Atlantic. Deep-Sea Research, 29: 171-184. References contd

 Todd, C.D. & Doyle, R.W. 1981. Reproductive strategies of marine benthic invertebrates; a settlement-timing hypothesis. Marine Ecology Progress Series, 4: 75-83.

 Young, C.M. Novelty of “supply-side ecology”. Science, 235: 415-416.

 Young , C.M. 1994. A tale of two dogmas: the early history of deep-sea . In: Young, C.M & Eckelbarger, K. J. (eds) Reproduction, larval biology and recruitment of the deep-sea benthos. Columbia University Press, New York. pp 1-25.