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Movement of Marine Organisms

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lorenap
30 diapositives · 398 Views · Jan 03, 2020

Movement of Marine Organisms. Dispersal versus Migration. DISPERSAL: UNDIRECTED. MIGRATION: DIRECTED, RETURN SPECIFIC. Migration Scheme. Migration Types. ANADROMOUS - fish live as adults in salt water, spawn in fresh water (shad, striped bass), more common in higher latitudes

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Movement of Marine Organisms
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  1. Movement of Marine Organisms

  2. Dispersal versus Migration DISPERSAL: UNDIRECTED MIGRATION: DIRECTED, RETURN SPECIFIC

  3. Migration Scheme

  4. Migration Types • ANADROMOUS - fish live as adults in salt water, spawn in fresh water (shad, striped bass), more common in higher latitudes • CATADROMOUS - fish live as adults in fresh water, spawn in salt water (eel), more common in lower latitudes • DIADROMOUS = ANADROMOUS + CATADROMOUS • FULLY OCEANIC - herring, green turtle

  5. Migration

  6. Migration of the herring in the North Sea

  7. Larval Dispersal

  8. Dispersal Types in Benthic Species • PLANKTOTROPHIC DISPERSAL - female produces many (103 to 106) small eggs, larvae feed on plankton, long dispersal time (weeks), some are very long distance (teleplanic) larvae - cross oceans • LECITHOTROPHIC LARVAE - female produces fewer eggs (102 to 103), larger, larvae live on yolk, short dispersal time (hrs to days usually) • DIRECT RELEASE - female lays eggs or broods young, juveniles released and crawl away • Combinations of above? Yes, but rare

  9. Lecithotrophic larva: tadpole larva of the colonial ascidian Botryllus schlosseri Pluteus larva of an urchin Planktotrophic larva of snail Cymatium parthenopetum

  10. Loss to offshore waters Wind-driven recruitment onshore Internal waves, tidal bores Self-seeding eddies Longshore drift Shore Population

  11. Effect of local eddies on larval retention in a patch reef on the Great Barrier Reef, Australia

  12. Two modes of beginning of larval life

  13. Estuarine larval adaptations - Retention Larvae rise on the flooding tide, sink to bottom on the ebbing tide: results in retention of larvae within estuary

  14. Falling Rising Fiddler Crabs - Lopez and Tankersley 2007

  15. Estuarine larval adaptations - movement of larvae to coastal waters, return of later stage larvae Blue crab, Callinectes sapidus

  16. Epifanio and Garvine 2001 Estuarine and Coastal Shelf Sci. v. 52: 51-77 Estuarine flow, southward transport Mixing northward, upwelling Mixing onshore from southward winds, Aug-Sept

  17. Larvae onto the Shelf - the Fatal Blow? • Estuarine loss to shelf - can they come back? • Upwelling - loss of larvae to open sea?

  18. Estuarine Loss - Problem of Loss from Estuarine Flow Buoyant flow - larvae leave estuaries for open sea, good to allow larvae to feed on plankton on shelf, perhaps to avoid predation. But will they ever come back? Possible solution - seasonal alternation of buoyant flow combined with upwelling favorable winds (summer) and shoreward favorable winds later in August and fall, bringing larvae toward shore Natunewicz et al. 2001 Marine Ecology Progress Series 222:143-154

  19. Blue crab Callinectes sapidus

  20. Upwelling - Guaranteed loss? • Relaxation of upwelling • Upwelling moves toward shore • Larvae sink below surface upwelling waters Consuelo Montero Concholepas concholepas see Poulin et al. Limnology Oceanography 47:1248-55 (2002)

  21. Settling Problems of Planktonic Larvae • Presettling problems: Starvation Predation in plankton Loss to inappropriate habitats

  22. Example of Effect of Starvation: Phytoplankton variation and barnacle larval success Semibalanus balanoides settlement in a Scottish Sea Loch

  23. Postsettling Problems • Energetic cost of metamorphosis • Predation • Crowding --> mortality Initial 6 months 12 months Expectation of life (months) 18 months 2 Interindividual contacts per cm Expectation of life of Semibalanus balanoides as function of crowding

  24. Two Scales of Larval Dispersal and Settlement Large scale - 10-103 km Small scale movements to take advantage of currents, seasonal release and settlement 2. Smaller scale - 10-2 - 102 m Positive, neg phototaxis, timing, near cues (< 10-1 m)

  25. Stages in the selection of substratum by planktonic larvae

  26. Stages: Larvae are competent Larvae seek bottom (photo+ photo-, timing) (Melampus bidentatus) Larvae seek further cues Substratum - cracks, shade Gregarious settling - members of own species - chemical cues (oysters: peptide, Hydroides sp.), very short distances - mm Settling on other species (Proboscidactylidae, bryozoans) Larvae make final movements - find local spot, space from others (Spirorbis), currents good for adults (barnacle larvae)

  27. Instructor: Recommend that you find images from the site below Nauplius (feeding) Cypris (non-feeding) Barnacle larvae http://www.microscopy-uk.org.uk

  28. Why disperse? • Local extinction - to export young • Hedging bets - spread over habitats • Not for dispersal! Feeding in plankton

  29. The End