Expanding dispersal studies at hydrothermal vents through species identification of cryptic larval forms

Abstract

15The rapid identification of hydrothermal vent-endemic larvae to the species level is a key 16 limitation to understanding the dynamic processes that control the abundance and 17 distribution of fauna in such a patchy and ephemeral environment. Many larval forms 18 collected near vents, even those in groups such as gastropods that often form a 19 morphologically distinct larval shell, have not been identified to species. We present a 20 staged approach that combines morphological and molecular identification to optimize 21 the capability, efficiency, and economy of identifying vent gastropod larvae from the 22 northern East Pacific Rise (NEPR). With this approach, 15 new larval forms can be 23 2 identified to species. A total of 33 of the 41 gastropod species inhabiting the NEPR, and 1 26 of the 27 gastropod species known to occur specifically in the 9° 50' N region, can be 2 identified to species. Morphological identification efforts are improved by new 3 protoconch descriptions for Gorgoleptis spiralis, Lepetodrilus pustulosus, Nodopelta 4 subnoda, and Echinopelta fistulosa. Even with these new morphological descriptions, the 5 majority of lepetodrilids and peltospirids require molecular identification. Restriction 6 fragment length polymorphism digests are presented as an economical method for 7 identification of five species of Lepetodrilus and six species of peltospirids. The 8 remaining unidentifiable specimens can be assigned to species by comparison to an 9 expanded database of 18S ribosomal DNA. The broad utility of the staged approach was 10 exemplified by the revelation of species-level variation in daily planktonic samples and 11 the identification and characterization of egg capsules belonging to a conid gastropod 12Gymnobela sp. A. The improved molecular and morphological capabilities nearly double 13 the number of species amenable to field studies of dispersal and population connectivity. 14 15

Larvae from deep-sea methane seeps disperse in surface waters

“…childressi and other bathymodiolin larvae are a distinctive pink colour [13,31], and B. naticoidea veligers are smaller than the coastal and estuarine neritid larvae that may be present in the Gulf of Mexico. Identifications based on morphology viewed under light microscopy were further corroborated with either analysis of the larval shell using SEM ( A similar multistep approach to larval identification has been used to identify species of mytilid mussel post-settlers [20] and hydrothermal vent larvae [35]. Table 1 includes individuals identified based on morphology as viewed under light microscopy only if we could confirm the identity of individuals with similar morphotypes via SEM or sequencing.…”

“…A similar multistep approach to larval identification has been used to identify species of mytilid mussel post-settlers [20] and hydrothermal vent larvae [35]. Table 1 includes individuals identified based on morphology as viewed under light microscopy only if we could confirm the identity of individuals with similar morphotypes via SEM or sequencing.…”

Microbial biofilms associated with fluid chemistry and megafaunal colonization at post-eruptive deep-sea hydrothermal vents

“…Siboglinid tubeworms too small for unambiguous morphological classification were identified using Restriction Fragment Length Polymorphism (RFLP) analyses and DNA sequencing of mtCOI as previously described in Shank et al (1999) and Adams et al (2010).…”

Functional traits provide new insight into recovery and succession at deep‐sea hydrothermal vents

“…For each sandwich or block, specimens were visually inspected under a dissecting microscope and identified morphologically to species or the lowest possible taxonomic level. Species-level identification of many juveniles was possible by comparing morphology to adults that retain larval characteristics (Adams et al 2010). Individuals that were too young to identify to species were grouped by genus or family.…”