Undergraduate Honors Theses

Thesis Defended

Spring 2017

Document Type

Thesis

Type of Thesis

Departmental Honors

Department

Ecology and Evolutionary Biology

First Advisor

Dr. Carol Kearns

Second Advisor

Dr. Heidi Souder

Third Advisor

Dr. Pieter Johnson

Fourth Advisor

Dr. Julie K. Lundquist

Abstract

Anthropogenic increases in global temperatures and nutrient loads are expected to reduce juvenile blue crab (Callinectes sapidus) survival in the Chesapeake Bay. These factors change habitat composition which can affect juvenile invertebrates and fishes that are dependent on these habitats. Eelgrass (Zostera marina) is declining due to rising water temperatures and increased nutrient loading, while widgeon grass (Ruppia maritima) can tolerate higher temperatures. An indoor mesocosm experiment was designed to test the suitability of Zostera and Ruppia as protective nursery habitats compared to sand. Artificial seagrass plots were placed in flow-through tanks. Juvenile blue crabs were tethered, and adult blue crabs and striped burrfish were introduced as predators in order to estimate juvenile crab survival in different substrates. Survival analysis revealed that Zostera provides more protection for juvenile crabs than sand. There was no significant difference between Ruppia and sand, and between Zostera and Ruppia in providing juvenile protection. This suggests juvenile survival may decrease in the future with Zostera loss and that stricter restrictions on the blue crab fishery in the Chesapeake Bay and mid-Atlantic region would be required to maintain healthy crab populations.

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