Coral-eating seastar Culcita novaeguineae data (binary predation version)

This data shows the results from a block design experiment to record the interactions of ‘guard’ crustaceans, shrimp (Alpheus lottini) and crab (Trapezia serenei), that defend their coral host (Pocillopora cf. meandrina) from seastar predators (Culcita novaeguineae) (McKeon et al. 2012) . The coral and their seastar predator were placed in large, octagonal, flow-through seawater tanks measuring approximately 0.5m deep and 2m in diameter. There were 10 tanks in total, each serving as an experimental block. Four treatment groups were tested: (1) no exosymbionts, (2) shrimp only, (3) crab only, and (4) both crab and shrimp present. Each treatment was replicated twice within each block.

Usage

data("culcitalogreg")

Format

A data frame with 80 observations on the following 9 variables.

block

a numeric variable indicating the experimental block. There are 10 blocks in total, each corresponding to a large, octagonal, flow-through seawater tank approximately 0.5m deep and 2m in diameter.

ttt

a number which represents the combinations of different symbionts.

• 1: no exosymbionts,

• 2: pair of Alpheus lottini only (Alpheus; shrimp),

• 3: pair of Trapezia serenei only (Trapezia; crab),

• 4: pair of Alpheus lottini and pair of Trapezia serenei (‘Alpheus and Trapezia’).

predation

(binary) indicates whether the seastar predator consumed the coral. 0 = did not eat; 1 = ate.

ttt.1

a relabelled version of ttt that explicitly indicates the corresponding treatment condition in plain language.

crab

describes whether the crab was present in the experiment. C-: not present, C+: present.

shrimp

describes whether the shrimp was present in the experiment. S-: not present, S+: present.

ttt2

a relabelled version of ttt that uses letters (a, b, c, d) instead of numeric values (1, 2, 3, 4), respectively, to represent the treatment groups.

crab2

a relabelling of crab where n corresponds to C- (no crab), and y corresponds to C+ (crab present).

shrimp2

a relabelling of shrimp where n corresponds to S- (no shrimp), and y corresponds to S+ (shrimp present).

Details

Full details of the experiment (McKeon et al. 2012) , is quoted below: "Twenty replicates in total were conducted for each exosymbiont treatment in a temporally blocked design with two replicates in each of ten temporal blocks. Trials were conducted in a large octagonal flow-through seawater tank approximately 0.5 m deep and 2 m across. The tank was divided into eight equal sections using plastic screening. Each section was provisioned with a seastar refugium constructed from concrete blocks. We placed Pocillopora colonies into the tank from the field during mid- to late afternoon. To minimize variation driven by search time, a single Culcita was placed directly on top of the coral colony. The following morning, we measured the coral size (length, width, height) and the feeding scars left by the Culcita (length, width, depth)."

See also

The version which only contains predation counts but includes the amount of volume of the coral and the amount of volume lost, culcitalvolume.

Source

(McKeon et al. 2012)

References

McKeon CS, Stier AC, McIlroy SE, Bolker BM (2012). “Multiple defender effects: synergistic coral defense by mutualist crustaceans.” Oecologia, 169(4), 1095–1103. doi:10.1007/s00442-012-2275-2 .

Examples

cul_mod <- glmer(predation ~ ttt2 + (1|block), data=culcitalogreg,
                     family = binomial(link = "logit"))