The effect of plant coverage on macro-invertebrate density and diversity in the intertidal

zone

Sarah Park, Bailey Shuttleworth Cucinelli,

James Holobow, and Jenna Shaw

Introduction● Ecologically important region

● Few studies on the effects of flora on faunal biodiversity

● Goal: provide greater understanding of marine interactions

Indian Point

Green’s Point

Bar Road

Ascophyllum nodosum

Fucus vesiculosus

Polysiphonia lanosa

Fauna

Littorina obtusataLittorina littorea Thais lapillus

FaunaBalanus balanoides Gammarus oceanicus

Invertebrate Density

● L. obtusata and G. oceanicus live in patches of seaweed

● L. littorea feed on algae

● B. balanoides and T. lapillus seek shelter from wave action

● Large and aggregated vegetation shelter greater number of invertebrates

Hypothesis 1:

● Amount of plant cover on intertidal regions of the Bay of Fundy is positively correlated with invertebrate density.

Invertebrate Biodiversity

● High biodiversity → stable and productive communities

● Schooner (1974): niche diversification/complex habitats may increase species richness○ quantify habitat complexity?

● Gunnill (1982): artificial increase and diversity may decrease with increased plant cover

Hypothesis 2:

● Amount of plant cover on intertidal regions of the Bay of Fundy is negatively correlated with invertebrate biodiversity.

Materials● line transect● 1 m quadrat● 25 cm quadrat● plastic collection bags for

samples

● ten sites over 100 m● constant altitude● surface species were

collected ● identified in the lab

Methods

Results

Discussion Indian Point

● Lowest plant cover (3.9 samples/m2)● Second largest fauna density (173.1

samples/m2)● Second highest diversity

(H’=0.307)Hypothesis 1: Not AcceptedHypothesis 2: Accepted

Discussion Green’s Point

● Largest plant cover (42.8 samples/m2)● Lowest fauna density (97.2 samples/m2)● Greatest diversity (H’=0.683)

Hypothesis 1: Not AcceptedHypothesis 2: Not Accepted

Discussion Bar Road

● Second Highest plant cover (7.2 samples/m2)

● Largest fauna density (275.8 samples/m2)● Lowest diversity (H’=0.088)Hypothesis 1: AcceptedHypothesis 2: Accepted

Sources of Error

• hard to distinguish holdfasts in high density of plants

• distance from the water’s edge was not measured

• inconsistent tide phase• time restriction

Conclusion

- Our study did not produce concrete results - Overall data is inconsistent- Multiple factors (abiotic/biotic) influence invertebrate density/diversity.