19 research outputs found
Expanding dispersal studies at hydrothermal vents through species identification of cryptic larval forms
Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Marine Biology 157 (2010): 1049-1062, doi:10.1007/s00227-009-1386-8.The rapid identification of hydrothermal vent-endemic larvae to the species level is a key
limitation to understanding the dynamic processes that control the abundance and
distribution of fauna in such a patchy and ephemeral environment. Many larval forms
collected near vents, even those in groups such as gastropods that often form a
morphologically distinct larval shell, have not been identified to species. We present a
staged approach that combines morphological and molecular identification to optimize
the capability, efficiency, and economy of identifying vent gastropod larvae from the
northern East Pacific Rise (NEPR). With this approach, 15 new larval forms can be
identified to species. A total of 33 of the 41 gastropod species inhabiting the NEPR, and
26 of the 27 gastropod species known to occur specifically in the 9° 50’ N region, can be
identified to species. Morphological identification efforts are improved by new
protoconch descriptions for Gorgoleptis spiralis, Lepetodrilus pustulosus, Nodopelta
subnoda, and Echinopelta fistulosa. Even with these new morphological descriptions, the
majority of lepetodrilids and peltospirids require molecular identification. Restriction
fragment length polymorphism digests are presented as an economical method for
identification of five species of Lepetodrilus and six species of peltospirids. The
remaining unidentifiable specimens can be assigned to species by comparison to an
expanded database of 18S ribosomal DNA. The broad utility of the staged approach was
exemplified by the revelation of species-level variation in daily planktonic samples and
the identification and characterization of egg capsules belonging to a conid gastropod
Gymnobela sp. A. The improved molecular and morphological capabilities nearly double
the number of species amenable to field studies of dispersal and population connectivity.Funding was provided by as Woods Hole Oceanographic Institution Deep Ocean
Exploration Institute grant to L.M and S. Beaulieu, National Science Foundation grants
OCE-0424953, OCE-9712233, and OCE-9619605 to L.M, OCE-0327261 to T.S., and
OCE-0002458 to K. Von Damm, and a National Defense Science and Engineering
Graduate fellowship to D.A
Increasing the Depth of Current Understanding: Sensitivity Testing of Deep-Sea Larval Dispersal Models for Ecologists
Larval dispersal is an important ecological process of great interest to conservation and the establishment of marine protected areas. Increasing numbers of studies are turning to biophysical models to simulate dispersal patterns, including in the deep-sea, but for many ecologists unassisted by a physical oceanographer, a model can present as a black box. Sensitivity testing offers a means to test the models' abilities and limitations and is a starting point for all modelling efforts. The aim of this study is to illustrate a sensitivity testing process for the unassisted ecologist, through a deep-sea case study example, and demonstrate how sensitivity testing can be used to determine optimal model settings, assess model adequacy, and inform ecological interpretation of model outputs. Five input parameters are tested (timestep of particle simulator (TS), horizontal (HS) and vertical separation (VS) of release points, release frequency (RF), and temporal range (TR) of simulations) using a commonly employed pairing of models. The procedures used are relevant to all marine larval dispersal models. It is shown how the results of these tests can inform the future set up and interpretation of ecological studies in this area. For example, an optimal arrangement of release locations spanning a release area could be deduced; the increased depth range spanned in deep-sea studies may necessitate the stratification of dispersal simulations with different numbers of release locations at different depths; no fewer than 52 releases per year should be used unless biologically informed; three years of simulations chosen based on climatic extremes may provide results with 90% similarity to five years of simulation; and this model setup is not appropriate for simulating rare dispersal events. A step-by-step process, summarising advice on the sensitivity testing procedure, is provided to inform all future unassisted ecologists looking to run a larval dispersal simulation