studying complexity of mesozoic tethyan food webs to ......1 studying complexity of mesozoic tethyan...

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Studying complexity of Mesozoic Tethyan food webs to understand

ecosystem restructuringSORMAN, Melanie G.1, DINEEN, Ashley A.2, TYLER, Carrie L.1 and ROOPNARINE, Peter D.2

(1)Department of Geology and Environmental Earth Science, Miami University, Oxford, OH(2)Department of Invertebrate Zoology and Geology, California Academy of Sciences, San Francisco, CA

Normile, 2016

Does Ecosystem Structure Change Through Time?

Dunne et al., 2008 Bush and Bambach, 2011

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Mesozoic Marine Revolution (MMR)

• Abrupt ecosystem reorganization due to increasing predation pressure

• Changes in community structure• Diversification of

predators

• New modes of life

• Greater ecosystem complexity?

Duria Antiquior - Beche

Hypothesis

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• Middle Triassic and Jurassic networks

• Testing effects of increasing predation pressure on marine communities by comparing trophic organization of both networks

• Does ecological complexity increase or change across the MMR?

Tethys

OceanGondwana

Laurasia

Middle Jurassic Scotese, 2001

Integrity of Fossil Food Web StructureModern Caribbean Reef Predicted Fossil Reef

Preserves:

58% of species

66% of genera

42% of guilds

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756 species249 nodes (guilds)Connectance 0.066

441 species163 nodes (guilds)Connectance 0.065

Roopnarine and Dineen, 2018

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Olson & Watters, 2003

Constructing a Food Web

• Step 1: Species List

• Step 2: Ecological Parameterization

• Step 3: Guilds and trophic interactions

• Step 4: Metanetwork

Metrics to Study MMR Structural Changes

Structural Metrics Anisian Bathonian

Species Richness 1185 1363

Guild Richness 105 117

Number of Trophic Links 1006 1000

Linkage Density 9.57 8.55

Connectance 0.0912 0.0731

Number of Trophic Levels 4.88 5.01

Modularity 0.341 0.369

Average Path Length 1.81 1.91

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• Trends characteristic of the MMR• Diversification of predators

• Increased infaunalization

• Larger body sizes

• Increased richness

Functional Diversity

• Species and guild richness increase

• Suggests MMR led to an increase in functional richness

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1100

1150

1200

1250

1300

1350

1400

Anisian Bathonian

Tota

l Sp

ecie

s

Species Richness

95

100

105

110

115

120

Anisian Bathonian

Tota

l Gu

ilds

Guild Richness

Trophic Levels• Slight increase in number of trophic levels

• Distribution of trophic levels similar

• Increased suspension feeders in 2nd trophic level• More higher trophic levels (depend on increased primary productivity)

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0

10

20

30

40

50

60

70

1 2 3 4 5

Gu

ild R

ich

nes

s

Trophic Level

Trophic Level Vs. Number of Guilds

Anisian

Bathonian

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Taxa

Pliosaurs, ichthyosaurs, plesiosaurs

Durophagous sharks/rays, cephalopods

Lobsters/crabs, deposit feeders, grazers, benthic carnivores

Suspension feeders, detritivores, microzooplankton

Bacteria, detritus, dinoflagellates, macroalgae

Bathonian Trophic Levels

Trophic Level

1

2

3

4

5

Bottom-up Cascades

11Knoll and Follows, 2016

0

1

2

3

4

5

6

0 5 10 15 20 25 30 35 40 45 50

Tro

ph

ic L

evel

New Guilds

Trophic Levels of New Guilds Present in Bathonian

New Body Size Guilds

New Life Mode Guilds

New Guilds Present in Bathonian• 48 new guilds

• Increased primary producer and predator guilds

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Chemosymbiotic infaunal bivalves, polyplacophora, herbivorous gastropods

Suspension feeders Benthic organisms (carnivorous and omnivorous/grazing gastropods, asteroidean, carnivorous bivalves)

Predators (sharks/rays, chimaeras, sea turtles, cephalopods, fish, eosauropterygia, ichthyosaurs, pliosaurs)

New Life Mode Guilds (N: 15)

Benthic grazing polyplacophora

Benthic herbivorous gastropods

Nektobenthic carnivorous chimaeras

Nektobenthic carnivorous durophagous rays

Boring suspension feeding bivalves

Deposit feeding/grazing sea stars

Mobile infaunal carnivorous bivalves

Hermit crabs

Pliosaurs

Sea turtles

Nektobenthic carnivorous sharks/rays

Nektobenthic carnivorous fast predatory fish

Heteromorph ammonites

Suspension feeding fish

New Body Size Guilds (N: 33)

Chemosymbiotic (Infaunal)(1)



Suspension Feeder IX Epibiont Epifaunal(2)




Suspension Feeder V Mobile Infaunal(10)




Suspension Feeders III Stationary Epifaunal(13)




Suspension Feeders VII Epibiont SemiInfaunal(1)




Benthic Omnivore/Grazers I(3)




Benthic Carnivores III Epifaunal Gastropods(4)

Benthic Carnivores III Epifaunal Gastropods(9)

Nektonic Carnivores V Ammonites(3)

Nektonic Carnivores III Fast Predatory Fish(4)



Marine Reptiles II Piercing Predatory Reptiles(11)



Marine Reptiles III Smash/Crunch Predatory Reptiles(8)

Body Sizes • Larger organisms in Bathonian

• Coincides with radiations of phytoplankton

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0

500

1000

1500

2000

2500

3000

3500

4000

0 10 20 30 40 50

Len

gth

(m

m)

Species Richness

Fish Body Sizes

0

200

400

600

800

1000

1200

0 10 20 30 40 50

Sku

ll Si

ze (

mm

)

Species Richness

Reptile Skull Sizes

Avg: 505 mm

Avg: 246 mm

Leedsichthys out of graph (22000 mm)

Avg: 320 mm

Avg: 1623 mm

0

50

100

150

200

250

300

350

400

450

0 50 100 150 200 250 300

Dia

me

ter

(mm

)

Species Richness

Cephalopod Body Sizes

Avg: 95 mm

Avg: 66 mm

0

200

400

600

800

1000

1200

1400

0 100 200 300 400

Len

gth

(m

m)

Species Richness

Suspension Feeder Body Sizes

Avg: 61 mm Avg: 66 mm

0

20

40

60

80

100

120

140

160

180

200

0 20 40 60 80 100

Len

gth

(m

m)

Species Richness

Deposit Feeders/Grazer Body Sizes

Key

Avg: 26 mm Avg: 43 mm

Modules • Bathonian is partitioned into fewer subcommunities

• Suspension feeders form the largest subcommunity

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BM0

N: 23

BM1N: 61

BM2N: 33

AM3N: 48

AM2N: 32

AM1N: 4

AM0N: 21

63% suspension feeders 72% suspension feeders

Benthic organismsPredatorsBenthic organisms and zooplankton

Predators

MicrozooplanktonBathonianModularity: 0.369

AnisianModularity: 0.341

Infaunal and Epifaunal Life Modes• Increased predation and bioturbation in MMR

• Shift to deeper waters or infaunalization

• Increase in infaunalization in both species and guild richness

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Anisian Bathonian

Total Semi-Infaunal Species 23 23

Number of Semi-Infaunal Guilds 4 6

Total Infaunal Species 73 128

Number of Infaunal Guilds 16 19

Total Epifaunal Species 429 606

Number of Epifaunal Guilds 36 49

0

10

20

30

40

50

60

Semi-Infaunal Infaunal Epifaunal

Gu

ild R

ich

nes

s

Number of Infaunal, Epifaunal, and Semi-Infaunal Guilds

Anisian

Bathonian

Epifaunal Semi-Infaunal

0

100

200

300

400

500

600

700

Semi-Infaunal Infaunal Epifaunal

Spec

ies

Ric

hn

ess

Number of Infaunal, Epifaunal, and Semi-Infaunal Species

Anisian

Bathonian

Len

gth

(m

m)

Anisian

Anisian

Bathonian 9.4%

Bathonian 44.4%

Average Path Length

• Bathonian has longer trophic chains

• More complex and inefficient!

• Makes sense given ecosystem restructuring

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Conflicting Metrics

• Higher values of linkage density and connectance may lead to increased complexity

• Not supported here

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Conclusions• MMR: increased predation pressure changes ecosystems

• Anisian to Bathonian: Increase in primary productivity led to increased energy transfer and higher trophic levels

• Triggered ecosystem restructuring and changes in energy transfer pathways, facilitated by radiation of phytoplankton

• Ecosystem structure has changed

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Acknowledgments• Dr. Carrie Tyler, research advisor and committee member

• Dr. Peter Roopnarine, California Academy of Sciences (CAS) collaborator and committee member

• Ashley Dineen, CAS collaborator

• Dr. Hailiang Dong, committee member

• Hannah Goggin, undergraduate research partner

• Joe Tawil, undergraduate research partner

• Ian Castro, research partner

• Hannah Kempf, research partner

• Lyndsey Farrar, research partner

• Paleobiology Database

• Funding sources

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EAR SGP 1629786EAR SGP 1629776

Questions?

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studying complexity of mesozoic tethyan food webs to ......1 studying complexity of mesozoic tethyan...

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