DOI: 10.5061/dryad.19342
title: Data from: Physical and biological factors affect the vertical distribution of larvae of benthic gastropods in a shallow embayment

description: Marine gastropods form a diverse taxonomic group, yet little is known
 about the factors that affect their larval distribution and abundance. We
 investigated the larval vertical distribution and abundance of 9
 meroplanktonic gastropod taxa (Margarites spp., Crepidula spp., Astyris
 lunata, Diaphana minuta, Littorinimorpha, Arrhoges occidentalis, Ilyanassa
 spp., Bittiolum alternatum and Nudibranchia), with similar morphology and
 swimming abilities, but different adult habitats and life-history
 strategies. We explored the role of physical (temperature, salinity,
 density, current velocities) and biological (fluorescence) factors, as
 well as periodic cycles (lunar phase, tidal state, diel period) in
 regulating larval vertical distribution. Using a pump, we collected
 plankton samples at 6 depths (3, 6, 9, 12, 18 and 24 m) at each tidal
 state, every 2 h over a 36 and a 26 h period, during a spring and neap
 tide, respectively, in St. George’s Bay, Nova Scotia. Concurrently, we
 measured temperature, salinity, density, fluorescence (as a proxy for
 chlorophyll, i.e. phytoplankton density), and current velocity. Larval
 abundance was most strongly related to temperature, except for
 Littorinimorpha and Crepidula spp., for which it was most strongly related
 to fluorescence. Margarites spp., A. lunata, Ilyanassa spp. and B.
 alternatum exhibited either diel or reverse-diel vertical migration during
 1 or both lunar phases. For Crepidula spp., Littorinimorpha, A.
 occidentalis and Nudibranchia, larval vertical distribution differed
 between lunar phases. Only the larval vertical distribution of Margarites
 spp., D. minuta and Ilyanassa spp. varied with tidal state during 1 or
 both lunar phases. The key factors determining the vertical distribution
 of gastropod larvae were temperature, fluorescence, and light, although
 the importance of each factor varied among taxa. Differences in vertical
 distribution may enable these larvae to partition over a wide range of
 potential habitats for settlement.
description: Vertical distribution
 measurements of Meroplanktonic gastropod larvae and the environment. A
 Canadian Healthy Oceans Network Population Connectivity project,
 PC-06This dataset was
 collected in the field (using a plankton pump, CTD, fluorometer and ADCP)
 for a MSc Thesis and 1 publication. This dataset contains the standardized
 abundance (count m-3) of meroplanktonic larvae (Margarites spp., Crepidula
 spp., Astyris lunata, Diaphana minuta, Littorinimorpha, Arrhoges
 occidentalis, lyanassa spp., Bittiolum alternatum, Nudibranchia),
 temperature, salinity, density, fluorescence, calculated Richardson number
 and current velocities (north-south, east-west, and vertical velocities)
 at 6 (3, 6, 9, 12, 18 and 24 m) depths, every 2 h over a 36- and 26-h
 sampling period, in St. George’s Bay, Nova Scotia, Canada. The dataset
 also included lunar cycle, diel period, tidal state, date, time, sampling
 depth, sampling depth range, and more.CHONE_PC-06_LLOYDM_dataset.csv