Apparent differential phenotypic responses by kelp forest grazers to disease-driven removal of sea star predators; [Data: Tegula shell morphology, GSI, stable isotope analysis]
Data files
Aug 23, 2024 version files 114.47 KB
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README.md
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Tegula_ProceedingsB_FullData_.xls
Abstract
The potential for aquatic gastropods to display phenotypic plasticity in response to predator cues is well documented in experimental settings. However, long-term physiological responses to predator exposure are difficult to evaluate at large scales in the field. Thus, it is currently unclear (a) the extent to which comparatively dilute predator cues experienced by natural snail populations influence morphometric development and (b) whether energetic costs associated with defensive morphology have allometric impacts on other life history characteristics (e.g., reproduction). The 2013 sea star wasting disease outbreak in central California, USA provided a unique framework for a large-scale natural predator removal experiment, comparing shell morphometrics and gonadosomatic index of subtidal Tegula turban snail populations at kelp forest sites where local predatory sea stars were completely absent (SS-) with paired sites maintaining low predator densities (SS+). All three snail species displayed significantly higher proportional allocation to shell mass at SS+ locations and concomitantly higher reproductive allocation with predators absent (SS-). Dietary stable isotope analysis suggests this may be partially an energetic consequence of behavioral grazing shifts displayed by snails following predator release. Interestingly, morphometric shifts in shell structure differed among the three Tegula species, and appeared closely related to species-specific predator avoidance strategies.
README: Apparent differential phenotypic responses by kelp forest grazers to disease-driven removal of sea star predators
GSI, shell morphology & stable isotope data for Tegula spp. in response to sea star wasting disease
Description of the data and file structure
Contains data on Tegula species, collection location, shell morphometric measurements, and biomass measurements for predator present (SS+) and predator absent (SS-) study sites in three central California study regions, with measurements in columns and individual samples in rows.
Variables
SampleID- Unique numerical identifier (1-300) randomly assigned to each individual snail at time of sample processing
Area- Categorical identifier designating the study region where an individual was collected: Monterey ("MON"), Big Sur ("BIS"), San Luis Obispo ("SLO")
SeaStar- Categorical identifier designating whether an individual was collected from a paired SS+ site with predatory sea stars present ("Present") or SS- site with predatory sea stars absent ("Absent")
Vert- Categorical identifier designating whether an individual was collected from vertical habitat on the stipes and fronds of giant kelp ("Vertical") or from benthic habitat in understory algae ("Benthic")
Spec- Categorical identifier designating* one of three Tegula species: T. brunnea* ("BRU"),* T. montereyi* ("MON"),* T. pulligo* ("PUL")
Sh_H- Shell height (measured in mm)
Sh_W- Basal shell width (measured in mm)
Apert_W- Aperture height (measured in mm)
Apert_H- Aperture width (measured in mm)
Sh_HW- Shell height: width ratio (= Aperture height/Aperture width)
Wt_Shell- Shell biomass (measured in g)
C (Raw)- Tissue stable isotope ratio of 13C (‰, raw laboratory data)
N (Raw)- Tissue stable isotope ratio of 15N ( ‰, raw laboratory data)
C (Correct)- Tissue stable isotope ratio of 13C (‰, corrected for isotopic fractionation using a trophic enrichment factor of 1.5‰)
N(Correct)- Tissue stable isotope ratio of 13C (‰, corrected for isotopic fractionation using a trophic enrichment factor of 1.5‰)
GSI- Gonadosomatic index, calculated as (Gonad Dry Weight/Total Soft Tissue Dry Weight) x 100
Ripeness- Categorical (binary numerical) identifier designating whether an individual displayed ripe gonads: (1) ripe or (0) not ripe
Sex- Categorical identifier designating the sex of an individual: ("F") Female or ("M") Male
SexCode- Categorical (binary numerical) identifier designating the sex of an individual: (1) Female or (0) Male
SI- Shell index, calculated as (Shell Weight/Total [Shell + Soft Tissue] Dry Weight) x 100
Wt_Tot- Total biomass, including Shell Weight + Soft Tissue Dry Weight (measured in g)
Wt_Soft- Total (dry weight) biomass of all soft tissue (measured in g)
Wt_Gon- Total (dry weight) biomass of gonad tissue (measured in g)
Methods
Dataset includes shell morphometric measurements and tissue (C & N) stable isotope analysis from subtidal Tegula turban snails (T. brunnea, T. montereyi, T. pulligo; total N = 300) collected from three regions along the central California coast. Field collections were conducted in 2014-2015 after the widespread outbreak of sea star wasting disease, and snails were collected haphazardly by divers on SCUBA from paired sites within each region, selected based on the presence (SS+) and absence (SS-) of predatory sea stars. Detailed methods for data collection and processing are published in Wetmore & Anderson (2024).