Table of Contents

• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Parameters
• Deployments
• Project Information
• Funding

Related Reference:

Belgrad, B. and B. Griffen. 2016. Predator-prey interactions mediated by prey personality and predator hunting mode. Proc. Roy. Soc. B: 283: 20160408. http://dx.doi.org/10.1098/rspb.2016.0408.

Related Datasets:

P. herbstii personality data
P. herbstii predator behavior data

We performed an experiment to assess the proportion of time individual mud crabs spend active vs hiding in refuge in the presence of predator odor cues from either a single toadfish, a single blue crab, or control conditions with no predator cue. Previous work by Toscano et al. (2014) determined that differences in this behavior between individuals persist over months (i.e. the behavior defines the personality of individuals). We collected 300 mature mud crabs that were not missing any limbs (mean ± SD carapace width = 24.1 ± 2.2 mm) by hand from intertidal oyster reefs within the North Inlet National Estuarine Research Reserve (33°20’N, 79°10’W, Georgetown, South Carolina). Crabs were collected in three cohorts of ten individuals during each of 10 blocked sampling periods (i.e., each blocked trial consisted of 30 crabs total). Individuals were randomly selected from 1 m² plots to ensure that natural cohorts of ten crabs were measured. Crab gender was identified by examination of the telson (167 males, 133 females).

Crabs were starved for 24 h and the carapace of each was marked with a unique nail polish (Sonia Kashuk) design to identify individuals. Preliminary work determined that these markings did not alter crab behavior. Cohorts were randomly assigned a predator cue treatment and placed into one of three separate flow-through mesocosms (circular with diameter 1 m; water height 15 cm). Each mesocosm contained ~2 cm sediment under a ~8 cm matrix of cleaned oyster shells covering the entire tank bottom. Thirty scorched mussels were distributed in three mesh containers within each mesocosm outside the reach of crabs to continuously stimulate foraging behavior [20]. Flow-through mesocosms were supplied with water from the estuary which was first pumped through a head tank. The head tank for each mesocosm contained either a mature toadfish (caudal length ± SD = 28.4 ± 2.8 cm), blue crab (carapace width ± SD = 14.8 ± 0.6 cm), or no predator depending on the predator odor cue treatment. Predators were caught from the estuary by dip net no more than one week prior to the experiment and fed mud crabs each day to ensure kairomones were produced. We conducted all experimental trials at night under red light following the observational procedures of Griffen et al. (2012) and Toscano et al. (2014)  to ensure mud crabs were at their most active and were undisturbed by the observer. 

Crabs were tested in trials consisting of one cohort per treatment (toadfish, blue crab, no predator) with six days separating the commencement of each trial. All trials began between the hours 2000-2100, and once cohorts were placed in the mesocosms, crabs were given 10 minutes to acclimate. After acclimating, we recorded whether crabs were actively exposed on the surface of the shell layer or were taking refuge underneath the shells at six minute intervals for the next three hours. The proportion of these 30 observations in which crabs hid in refuge and were not visible to the observer was used as our response variable.

Immediately after observing crab behavior (described in the last subsection), we used the same crab cohorts to assess whether crab predation risk was influenced by the proportion of time individual crabs spend in refuge within oyster shells and by predator species. We assigned crabs the same predator treatment they experienced previously to keep cohorts intact throughout the entire study.  Crabs were fed a satiating amount of fish (Fundulus heteroclitus), marked with individually-numbered bee tags (queen marking kit: the Bee Works, Orillia, Ontario, Canada), and starved for 24 h. After the starvation period, the cohorts were placed into one of three large flow-through mesocosms (diameter 2m; water height 90 cm). Each mesocosm contained ~ 2 cm of sediment underneath four clusters of live oysters (length ~38 cm, width ~31 cm, height ~28 cm) which were standardized by weight (15.000 kg within <0.1 %). Oysters were collected from the estuary and cleaned of any inhabiting crabs. Scorched mussels naturally attached to these collected oysters were standardized by number of individuals (within 8.3 %) and served as the mud crabs’ food source to mimic natural conditions.

During each blocked trial (n=10), a single toadfish, blue crab, or no predator (to serve as a control for cannibalism) was placed in each mesocosm depending on the experimental treatment. We used the same individual predators which provided odor cues in the previous behavior experiment as predators within the large mesocosms. Predators were starved 24 h to standardize hunger levels and placed in the mesocosms 10 minutes prior to the mud crabs to ensure kairomones were distributed throughout the tank (no crabs were lost to predation during introduction into the tanks). Mud crab survival was checked daily for seven consecutive days to determine which individuals were consumed.  This was done by removing all the oyster clumps and thoroughly raking the sediment. Any missing crabs were presumed dead as there was no way for crabs to escape and remnants of missing animals were often found.

We assessed whether crab mortality was influenced by the fixed effects of crab refuge use (measured in the first experiment), predator species, and crab size using a mixed-effects Cox proportional hazards model (i.e., a survival analysis) with trial as a random effect (R package: frailtyHL). This model allowed us to right censor the data to account for crabs that were not consumed by the end of the trial. A Cox proportional hazards analysis is a statistical model which recognizes that the highest values  in a study may simply be the maximum possible value because a result did not occur by the end of the observation period, so the model weighs the data points accordingly (i.e. the data are right censored). We also conducted a two-sample Kolmogorov-Smirnov test to compare the distribution of mud crab personality types consumed by blue crabs and toadfish. 

Statistical software: R, version 3.0.3 (R Development Core Team, Auckland, New Zealand; R Package frailtyHL v. 3.0.3) 

BCO-DMO Processing:

- added conventional header with dataset name, PI name, version date, reference information
- renamed parameters to BCO-DMO standard
- changed month names to numbers
- added ISO_DateTime_UTC and yrday for plotting purposes

Description from NSF award abstract:
A major goal of biological and ecological sciences is to understand natural systems well enough to predict how species and populations will respond to a rapidly changing world (i.e., climate change, habitat loss, etc.). A population under any conditions will grow, shrink, or disappear altogether depending on how efficiently individuals consume resources (food), utilize that food metabolically, and eventually reproduce. However, making accurate predictions based on these metabolic processes is complicated by the realities that each species has different resource requirements and that no two individuals within a species are exactly alike. Rather, individuals vary and this variation, both within and across species, is central to many ecological and evolutionary processes. Developing the ability to predict responses of biological systems to a changing world therefore requires a mechanistic understanding of variation. The goal of this project is to improve this mechanistic understanding by examining variation within a metabolic context across a range of species that have a spectrum of commonly-seen resource requirements. Further, the work capitalizes on a unique biological characteristic of this group of species that allows control and manipulation of individual reproduction, facilitating experimental study of the mechanistic links between variation in individual consumption, metabolism, and reproduction. The foundation this research is a combination of field measurements and laboratory experiments using both well-established and newly-developed techniques to quantify these links. The result will be a quantitative framework to predict how individuals will respond reproductively to changes in resource use. Because of the close link between individual reproduction and population dynamics, this research will contribute substantially to predictions in population dynamics under realistic conditions where individuals use more than a single resource, and improve the prediction of responses to current and future ecological changes.

The following publications and data resulted from this project:

Belgrad, B. and B. Griffen. 2016. Predator-prey interactions mediated by prey personality and predator identity.Proc. Roy. Soc. B: In Review. [2016-01-20]
P. herbstii mortality data: Mortality of crabs when exposed to either a single blue crab, toadfish, or no predator for a week
P. herbstii personality data: Refuge use of crabs when exposed to predator odor cues from either blue crabs, toadfish, or control of no cue
P. herbstii predator behavior data: Refuge use and mobility of blue crabs and toadfish while in mesocosms for a week - behavior measured during two days.

Belgrad, B. and B. Griffen. 2016. The influence of dietary shifts on fitness of the blue crab, Callinectes sapidus. PloS One. DOI: 10.1371/journal.pone.0145481.
Blue crab activity: Activity of crabs fed different diets over a summer
Blue crab egg size: Volume of eggs for crabs fed different diets
Blue crab hepatopancreas index (HSI): Weight of hepatopancreas for crabs fed different diets
Blue crab hepatopancreas lipid content: Hepatopancreas lipid content of crabs fed different diets
Blue crab reproductive tissue analysis (GSI): Gonadosomatic index of blue crabs on various diets
Blue crab survival: Blue crab survival data during the dietary study

Knotts ER, Griffen BD. 2016. Individual movement rates are sufficient to determine and maintain dynamic spatial positioning within Uca pugilator herds. Behavioral Ecology and Sociobiology 70:639-646
Uca pugilator: behavior change with carapace marking: Search space behavior due to carapace treatment (control, nail polish, and food dye)
Uca pugilator: field spatial position: Assessment of individual's position within a herd at 3 min. intervals; for proportion of time found at edge of herd
Uca pugilator: herd position proportion: Individual's proportion of time spent in an edge/alone position among a herd
Uca pugilator: search space distribution: Search space that crabs traveled; to evaluate the sample's distribution of exploratory behavior

Belgrad, B. and B. Griffen. 2015. Rhizocephalan infection modifies host food consumption by reducing host activity levels. Journal of Experimental Marine Biology and Ecology. 466: 70-75.
E. depressus digestion time : Time taken for food to pass through gut of flat-backed mud crabs infected by a parasite
E. depressus metabolism: Respiration rate of infected/uninfected flat-backed mud crabs
E. depressus reaction time to prey: Time taken for infected/uninfected flat-backed mud crabs to react to the presence of prey

Blakeslee, A.M., C.L. Keogh, A.E. Fowler, B. Griffen. 2015. Assessing the effects of trematode infection on invasive green crabs in eastern North America. PLOS One 10(6): e0128674.(pdf)
Carcinus: hemocyte density: Counts of circulating hemocyte density in Carcinus maenas
Carcinus: parasites physiology behavior: Behavior and physiology of Carcinus maenas infected with trematode parasite

Griffen BD, Norelli AP (2015) Spatially variable habitat quality contributes to within-population variation in reproductive success. Ecology and Evolution 5:1474-1483.
P. herbstii diet: sampling site characteristics (Eco-Evo 2015)
P. herbstii diet: body measurements (Eco-Evo 2015)
P. herbstii diet & reproduction (Eco-Evo 2015)
P. herbstii: collection sites (Ecol-Evol 2015)

Griffen BD, Riley ME (2015) Potential impacts of invasive crabs on one life history strategy of native rock crabs in the Gulf of Maine. Biological Invasions 17:2533-2544.
Cancer consumption and reproduction (Bio.Inv. 2015): Lab experiment linking dietary consumption and reproduction

Griffen BD, Vogel M, Goulding L, Hartman R (2015) Energetic effects of diet choice by invasive Asian shore crabs: implications for persistence when prey are scarce. Marine Ecology Progress Series 522:181-192.
Hemigrapsus diet 1 (MEPS 2015)
Hemigrapsus diet 2 (MEPS 2015)

Hogan and Griffen (2014). The Dietary And Reproductive Consequences Of Fishery-Related Claw Removal For The Stone Crab Menippe Spp. Journal of Shellfish Research, Vol. 33, No. 3, 795–804.
Stone crab: 052012-DietChoiceExp1: Prey choice for 2-clawed and 1-clawed Stone Crabs (Menippe spp.)
Stone crab: 052012-LongTermConsumption: Long-term consuption for 2-clawed and 1-clawed Stone Crabs (Menippe spp.), summer of 2012
Stone crab: 062013-DietChoiceExp2: Prey choice for 2-clawed and 1-clawed Stone Crabs (Menippe spp.)
Stone crab: 062013-PreySizeSelection: Prey Size selection ranking for 2-clawed and 1-clawed Stone Crabs (Menippe spp.)

Riley M, Johnston CA, Feller IC, and Griffen B. 2014. Range expansion of Aratus pisonii (mangrove tree crab) into novel vegetative habitats. Southeastern Naturalist 13(4): 43-38
A. pisonii: range expansion: Aratus pisonii survey in native mangrove and novel salt marsh habitats

Riley M, Vogel M, Griffen B. 2014. Fitness-associated consequences of an omnivorous diet for the mangrove tree crab Aratus pisonii. Aquatic Biology 20:35-43, DOI: 10.3354/ab00543
A. pisonii: fitness and diet: Impact of diet variation on physiological and reproductive condition of A. pisonii

Toscano BJ, Newsome B, Griffen BD (2014) Parasite modification of predator functional response. Oecologia 175:345-352b
E. depressus - parasite and feeding (Oecologia, 2014): Feeding with and without parasitic barnacle infection
E. depressus - parasite and prey handling (Oecologia, 2014): Food handling with and without parasitic barnacle infection
E. depressus - parasite study - field survey (Oecologia, 2014): Parasitised field survey

Toscano BJ, Griffen BD (2014) Trait-mediated functional responses: predator behavioural type mediates prey consumption.Journal of Animal Ecology 83:1469-1477
P. herbstii - activity and feeding (JAE, 2014): Activity level and feeding with and without predator cue

Toscano BJ, Gatto J, Griffen BD (2014) Effects of predation threat on repeatability of individual crab behavior revealed by mark recapture. Behavioral Ecology and Sociobiology 68:519-527
P. herbstii - recapture behavior (BESB, 2014): Mud crabs refuge use and activity level - initial measurements
P. herbstii - refuge use (BESB, 2014): Effect of predation threat on repeatability of individual crab behavior revealed by mark-recapture

Griffen BD, Altman I, Bess BM, Hurley J, Penfield A (2012) The role of foraging in the success of invasive species. Biological Invasions. 14:2545-2558
Hemigrapsus seasonal diet (Bio.Inv. 2012): Percent herbivory and gut fullness for Hemigrapsus sanguineus at different times of year

Griffen BD, Toscano B, Gatto J (2012) The role of intraspecific trait variation in mediating indirect interactions. Ecology 93:1935-1943
P. herbstii refuge use (Ecology, 2012): Proportion of time that Panopeus herbstii spent using refuge habitats in a lab experiment
P. herbstii: Field personality distribution (Ecology, 2012): Field distribution of personality types in the mud crab Panopeus herbstii relative to tidal height
P. herbstii: Trait mediated indirect effect (Ecology, 2012): Influence of refuge use by the mud crab Panopeus herbstii on consumption of bivalves

Riley ME, Griffen BD (2017) Habitat-specific differences alter traditional biogeographic patterns of life history in a climate-change induced range expansion.  PLOS One 12(5):e0176263
A. pisonii: egg size: Comparing egg size in Aratus pisonii populations from mangrove and salt marsh habitats
A. pisonii: fecundity: Determining fecundity of Aratus pisonii populations in mangrove and salt marsh habitats
A. pisonii: larval starvation resistance: Comparing larval quality in Aratus pisonii populations from mangrove and salt marsh habitats
A. pisonii: latitudinal body size: Survey examining latitudinal body size patterns in Aratus pisonii
A. pisonii: predation: Comparing predation pressure on Aratus pisonii in mangrove and salt marsh habitats
A. pisonii: reproductive effort: Survey comparing Aratus pisonii reproductive effort in native and novel habitats
A. pisonii: herbivory: Relationship between leaf herbivory, tree characteristics, and refuge availability
A. pisonii: mangrove tree survey: Mangrove tree distribution and characteristics in a dwarf mangrove system

Cannizzo ZJ, Dixon SR & Griffen BD (2018). An anthropogenic habitat within a suboptimal colonized ecosystem provides improved conditions for a range-shifting species. Ecology and Evolution, 8(3):1524-1533.
A. pisonii: behavior: Proportion of time the mangrove tree crab Aratus pisonii spent in different behaviors related to diet and energy storage
A. pisonii: dock-marsh thermal: Thermal readings from under a dock and in a nearby salt marsh
A. pisonii: sun-shade: Proportion of time that mangrove tree crab Aratus pisonii spent in sun and shade in three habitats, 2015-2016.
A. pisonii: thermal picture: Thermal condition of A. pisonii in three habitats: under dock, mangroves, saltmarsh