Chemical settlement cues

Prendergast GS, Zum CM, Bers AV, Head RM, Hansson LJ, Thomason JC (2008) Field-based video observations of wild barnacle cyprid behaviour in response to textural and chemical settlement cues. Biofouling 24 449 159... 

Chemically mediated interactions have important direct and indirect effects on communities from both ecological and evolutionary standpoints.22 341 Chemical defense or communication cannot be properly understood unless it is viewed through the lenses of population, community, and ecosystem processes, and this requires consideration of both the biotic and abiotic components of the natural environment.342 For example, chemically mediated foraging is affected by water flow because it relies on water-soluble cues that are carried away from prey.343 345 Similar constraints likewise modify the effectiveness of other waterborne cues, such as alarm signals, sexual pheromones, and settlement cues, in both mobile and sessile organisms.244 345 350... 

Zimmer-Faust, R.K. and Tamburri, M.N., Chemical identity and ecological implications of a waterborne, larval settlement cue, Limnol. Oceanogr., 39, 1075, 1994. 

Greer SP, Iken KB, McClintock JB, Amsler CD (2003) Individual and coupled effects of echino-derm extracts and surface hydrophobicity on spore settlement and germination in the brown alga Hincksia irregularis. Biofouling 19 315-326 Hadfield M, Paul VJ (2001) Natural chemical cues for settlement and metamorphosis in marine-invertebrate larvae. In McClintock JB, Baker BJ (eds) Marine Chemical Ecology. CRC Press, Boca Raton, FL, pp 431 161... 

Settlement and metamorphosis of barnacles in response to chemical cues appears more complex than for oysters, with several materials functioning as inducers of settlement (reviewed by Clare... 

Slattery, M., Chemical cues in marine invertebrate larval settlement, in Marine Woodboring and Fouling Organisms of the Indian Ocean A Review, Naghabushanum, R. and Thompson, J.F., Eds., Oxford and IBH Publishing Co., New Delhi, 1997, 135. 

Welch, J.M., Rittschof, D., Bullock, T.M., and Forward, R.B., Jr., Effects of chemical cues on settlement behavior of blue crab Calllinectes sapidus postlarvae, Mar. Ecol. Prog. Ser., 154, 143, 1997. 

Natural Chemical Cues for Settlement and Metamorphosis of Marine-Invertebrate Larvae... 

Considerable experimental evidence suggests that chemical cues are very important in substrate selection by larvae. In nature, chemical cues may interact with physical or hydrodynamic factors to induce larval settlement.5-7 Despite the evidence that chemical cues are extremely important for settling larvae, the complete chemical identity of the natural inducer molecules is known in very few cases.3-8-11 More commonly, partial chemical characterization has provided clues to the chemical identity of the natural inducers. These partially purified inducers are useful for studying the biology of larval settlement and metamorphosis.912-18... 

Another source of cues for larval settlement are the films of microorganisms (biofilms) found on most underwater surfaces. Microbial films have long been recognized as necessary for the settlement of some invertebrate larvae,23 and the settlement of many, but not all, groups of invertebrate larvae are facilitated by the presence of microbial films.3,24 In some cases, specific types of bacteria present in biofilms may be responsible for facilitating settlement,24-26 and chemicals bound to or released from bacteria may function as settlement inducers. 

There are many reasons why so few natural chemical inducers have been fully characterized. Larvae may respond to specific cues that are present only at very low concentrations therefore, obtaining adequate amounts of these inducers for purification and structural work may be problematic. The problem of adequate material may be particularly troublesome for the waterborne inducers and has hampered the study of the water-soluble cue from Porites corals that induces settlement in Phestilla sibogae. A second problem is the low number of collaborations between natural products chemists and larval biologists in the study of natural chemical inducers. However,... 

Separate cues for settlement and metamorphosis are reported for a disparate group of invertebrates. Larvae of the barnacle-eating nudibranch Onchidoris bilamellata (frequently referred to as 0. fusca in the literature) settle from the water column in response to a water-soluble metabolite released by living barnacles, which are the prey of the adult nudibranchs.51 However, the larvae metamorphose only if they make surface contact with the shell of a barnacle, leading the authors to conclude that the metamorphic inducer is a chemical associated with the surfaces of barnacles. The settlement process is reversible and repeatable. Curiously, Chia and Koss51 reported that larvae of 0. bilamellata will metamorphose on contact with shells of dead barnacles only if they are in seawater conditioned by live barnacles. This observation seems to suggest that a single soluble metabolite induces behavioral settlement, but that metamorphosis requires the inductive action of both that same factor plus one or more others, associated with barnacle shells. 

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