Susceptibility of invertebrate larvae to predators:how common are post-capture larval defenses?

Abstract

Predation is bel~eved to be a major source of mortal~ty for larvae of benthlc Invertebrates, but the palatab~hty of larvae commonly found In the water column has rarely been assessed Larval palatability assays were conducted by collecting live invertebrate larvae from a temperate f~e l d slte and offerlng them to a suite of common predators (the flshes Lagodon rhomboides, Leiostomus xanthurus, and Monacanthus h~s p~d u s and the hard coral Ocul~na arbuscula) By crushing larvae that were rejected intact and re-offering them to pledators it was poss~ble to distinguish between defenses based on morpholog~cal and chemical character~stlcs of the larvae Add~tlonally, abundance data were collected for taxonomic groups of larvae at our samphng location The majonty of Invertebrate larvae were palatable to consumers Most predators readily consumed polychaete larvae barnacle naupln, blvalve veligers shnmp zoeae, crab megalopae, phoronld actlnotrochs, and hemlchordate tornana (which together accounted for 65 "L of meroplankton abundance) s u g g e s t~n g that these larvae lacked effective morpholog~cal or chem~cal defenses Agalnst at least 1 fish predator, a significant number of gastropod vel~gers, barnacle cypnds, crab Loeae, and stomatopod larvae (which accounted for 34 % of meroplankton abundance) appeared to be morphologically defended Larvae from these groups tended to b e rejected whole, but \yere consumed by flshes once they were crushed A significant number of nemertean pilidia asterold biplnnana and c n~d a n a n planulae (which accounted for only 0 2 % of meroplankton abundance) were rejected both whole and crushed suggest~ng that some species or indlvlduals withln these taxa may be chemcally defended Thus, the majonty of larvae from t h s assemblage of temperate meroplankton lacked physlcal or chemlcal defenses a g a~n s t potential predators (3 flshes and 1 cnidallan) Among the remalrung larvae, physical resistance to predators was much more common t h~i n chemical resistance

Chemical defense in pelagic octopus paralarvae: Tetrodotoxin alone does not protect individual paralarvae of the greater blue-ringed octopus (Hapalochlaena lunulata) from common reef predators

“…In these taxa tradeoffs exist between defense and growth and reproduction. Bullard et al (1999) empirically observed that many pelagic larvae are chemically undefended. No young of any blue-ringed octopus have yet been examined for the presence of TTX or other evidence of chemical protection.…”

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

“…Chemical response varies strongly among species and is generally lacking among most 7 meroplankton, with morphological and physical resistance often more common features than 8 chemical defense itself (Bullard et al, 1999). Consequently, individual taxa should be considered 9 separately when assessing the role of predation on the coupling between larval-supply and 10 settlement and on overall community assemblages.…”

Early life history and settlement of the slender filefish, Monacanthus tuckeri (Monacanthidae), at Calabash Caye, Turneffe Atoll, Belize

“…Food availability could also create differences in habitat quality for M. tuckeri. However, Barrett (1999) found that food was not a limiting factor in growth of a temperate monacanthid in Australia, and Bullard et al (1999) found that an Atlantic monacanthid could readily consume a wide array of available microinvertebrate prey. M. tuckeri has a broad diet including algae, detritus and invertebrates 1 , so food is likewise unlikely to be a limiting resource for this species.…”