Kelly E. Hattori
with Patricia H. Kelley, Kristina Ottens, Nicholas O. Moore,
Sarah L. Simpson, Anna M. Zappulla, Gregory P. Dietl, and
Christy C. Visaggi
BACKGROUND
 Predatory gastropods frequently feed
upon bivalves
 Predation trace fossils
occur in fossil record
 Drilling predation studies useful for
examining community composition and
interactions
 Many sampling method options, including:
 Bulk
 Taxon-specific (targeted)
 Surveys (museum, monograph,
outcrop)
RESEARCH GOALS
Investigate:
1. Validity of taxon-specific (targeted) sampling as an
alternative to bulk sampling when select taxa are needed
for drilling predation studies
 Based on preliminary study conducted by Ottens et al.
(2012)
2. Effects of collector expertise on bias
in targeted samples
3. Effects of size variability of specimens
on bias in targeted samples
GENERA STUDIED / LOCALITY
A
B
C
D
 Lirophora latilirata (A)
 Cyclocardia granulata (B)
 Astarte concentrica (C)
 Glycymeris americana (D)
Location of Register Quarry in NC
COLLECTION METHODS
 Six bulk sample replicates taken during a Research
Experiences for Undergraduates project in June 2008
 Sieved using 5mm mesh
 ~ 2 liters of material per sample
 Each collector took five replicate targeted samples
 1m2 quadrat size
 25 specimen minimum per sample
Layout of Register Quarry with location of targeted replicates
MEASUREMENTS & CALCULATIONS
 Measured:
 Length and thickness
 Valve frequency (left versus
right)
 Drillhole presence, location,
and outer borehole diameter
 Calculated:
 Drilling frequency (DF)
Diagram of drillhole location sectors from Kelley (1988)
 Prey effectiveness (PE)
 Size and site selectivity
 Size-standardize data using parameters used by Ottens
et al. (2012)
STATISTICAL TESTS & ANALYSIS
 Methods and collector experience for both standardized
and unstandardized data
 Replicates analyzed in four groups:
1. All replicates separate
2. All replicates with a minimum of 10 specimens
3. All replicates with a minimum of 20 specimens
4. All replicates combined
 Mann-Whitney U tests, chi-squared tests, KolmogorovSmirnov one-sample tests, covariance tests
RESULTS –Drilling Predation Metric
Collector Standardized
Collector Unstandardized
0.6%
(n=1)
99.4%
(n=165)
4.7%
(n=16)
Number of tests
conducted: 1090
95.3%
(n=322)
Method Standardized
 Size-standardized data
show fewer significant
differences than
unstandardized data
Method Unstandardized
2.6%
(n=5)
Total specimens
collected: 6826
10.4%
(n=41)
 Taxon-specific
97.4%
(n=188)
sampling minimally
significantly different
from bulk sampling
results
89.6%
(n=352)
Significant
Non-significant
RESULTS - Taxon
Percentage of significant tests for each taxon
 Size variability
16.7
16
Percentage of Significant Tests
of Glycymeris
americana did
not cause
additional bias
in collected
targeted samples
18
15.1
14
12
10
8.3
7.1
8
6
6.8
5.2
4.6
4.8
4.5
4
2.2
 Bulk samples
frequently had
inadequate
sample sizes,
especially in less
common taxa
2
0
0
0
0
0
0
0
Astarte
Method Unstandardized
Cyclocardia
Method Standardized
Novice
Veteran
Bulk
Lirophora
Taxon
Collector Unstandardized
Glycymeris
Collector Standardized
Astarte Cyclocardia Lirophora Glycymeris
358
203
348
310
502
205
354
758
59
31
470
582
Percentage of Significant Tests
RESULTS – Collectors
14
Percentage of significant tests for each
veteran collector
12
10
 Novice collectors
11.9
did not differ
significantly from
veteran collectors
9.1
8
6.8
6
4.8
4.3
2.9
4
2
0
PK
GD
CCV
Veteran Collector
Method Unstandardized
Method Standardized
Percentage of significant tests for each novice collector
18
Percentage of Significant Tests
16
15.9
14.0
13.6
14
11.3
12
10.0
10
9.7
8
6
4.8 4.9
4.7
5.8
5.0
4
0
1.7
1.6
2
0
0
KEH
Method Unstandardized
0
NOM
0
SLS
Novice Collector
Method Standardized
0
AMZ
Collector Unstandardized
0
0
KO
Collector Standardized
CONCLUSIONS
1. Taxon-specific sampling is a
viable collection method for
drilling predation studies in
targeted species
 Limitations must be fully
understood
 Care must be taken to avoid
bias
 Sample size can be controlled
 More efficient
CONCLUSIONS
2. Novices are able to collect
samples of the same caliber
as those collected by veteran
collectors.

Must be properly trained in
identification, collection,
and measurement
techniques


More efficient
Larger pool of people to
assist with studies
Thank You!