CHEMICAL ECOLOGY OF MARINE INVERTEBRATE LARVAL SETTLEMENT Biofouling: control of settlement Aquaculture: shell-fisheries Ecological: distribution and

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1 CHEMICAL ECOLOGY OF MARINE INVERTEBRATE LARVAL SETTLEMENT Biofouling: control of settlement Aquaculture: shell-fisheries Ecological: distribution and abundance of benthos

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6 CATEGORIES OF SPECIFICITY: 1) settlement on biofilms (sediment) 2) gregarious settlement - conspecifics 3) associative settlement - prey, hosts

7 Barnacles exhibit all categories

8 Physical cues are important too

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11 Conopea galeatus on Lophogorgia chilensis

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13 Associative settlement

14 Gregarious settlement

15 GREGARIOUS SETTLEMENT GREGARIOUS SETTLEMENT Species Species Substratum Substratum Detection Detection Cue Cue Barnacles Barnacles conspecific conspecific surface surface proteinaceous proteinaceous? Balanus Balanus arthropodin arthropodin? Semibalanus Semibalanus actin actin? Oysters Oysters conspecifics conspecifics Crassostrea Crassostrea settlement settlement soluble soluble DOPA/melanin? DOPA/melanin? Ostrea Ostrea ammonia? ammonia? tripeptide tripeptide? -metamorphosis metamorphosis surface surface bacterial? bacterial? Tubeworm Tubeworm conspecifics conspecifics surface surface cement peptide? cement peptide? Phragmatopoma Phragmatopoma DOPA? DOPA? FFAs FFAs? Hydroides Hydroides conspecifics conspecifics? surface surface bacteria? bacteria?

16 ASSOCIATIVE SETTLEMENT Species Substratum Detection Cue Nudibranch corals soluble? (30 years!!) Phestilla Porites Abalone Haliotis crustose red algae adult mucus / microbial film surface GABA? peptide? Coral crustose red algae surface carbohydrate? Agaricia Sea urchin red alga soluble? carbohydrate: Holopneustes Delisea floridoside + isethionic acid

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18 A natural chemical cue that induces or deters settlement can be demonstrated to exist: 1) on or near the substratum 2) at effective concentrations 3) under natural conditions

19 Problems with assays of potential settlement inducers or antifouling compounds: 1) extracts or compounds pooled on a surface at high concentrations 2) physical characteristics of surface are altered 3) compounds solubilized in still water at unnaturally high concentrations 4) long-term, whole larva assays are subject to artifact

20 Why is it so difficult to isolate the natural chemical cues that affect marine invertebrate larvae? 1) Larvae are small, planktonic 2) Sensory organs are multifunctional 3) Water flow is complex 4) Cues are multiple and hierarchical

21 It is evident that there is need for new viewpoints, for more observations and, perhaps, for team-work between various disciplines not only of biology but of physics and chemistry as well before there will be a clearly acceptable hypothesis of metamorphosis. Only the beginnings have been made in this interesting field. W.F. Lynch (1961): Extrinsic factors influencing metamorphosis in bryozoan and ascidian larvae. Amer. Zool. 1:

22 Aplysia spp.

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24 Non specific -- but, for a mobile consumer, getting in the proper habitat may be a sufficient trade-off

25 CHEMICAL ECOLOGY OF MARINE INVERTEBRATE LARVAL SETTLEMENT: Part II A tale of two worms Phragmatopoma californica Hydroides dianthus

26 Cl. Polychaeta F. Sabellariidae Sabellaria Phragmatopoma

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37 16:0 Palmitic _ 16:1 cis 9 Palmitoleic 16:1 trans 9 Palmitelaidic 18:2 Linoleic 20:5 Eicosapentaenoic _ Response dependent on size, shape, functionality

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39 =?

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41 BUT... Morse s s group demonstrated activity of BHT could not detect FFAs in tube sand samples SO, is the response of Phragmatopoma non-specific??? PROBABLY NOT: 1) organic extraction of natural tubes results in loss of activity 2) FFAs are only component in organic extract that induces 3) Larvae of reef-building and non-reef reef-building species do not respond to FFAs or are deterred from settlement 4) Natural sand tubes of non-responsive, non-reef reef-building species has 1/10th the concentration of FFAs DOPA

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45 Larvae are not passive! Behavior is important.

46 100 μm 100 μm

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