Date of Award

8-2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

College/School

College of Science and Mathematics

Department/Program

Earth and Environmental Studies

Thesis Sponsor/Dissertation Chair/Project Chair

Paul A. X. Bologna

Committee Member

John J. Gaynor

Committee Member

Robert W. Meredith

Committee Member

James J. Campanella

Committee Member

Thomas Belton

Subject(s)

Molecular ecology, Introduced organisms

Abstract

Ecological communities are under constant pressure from anthropogenic disturbances. Marine and estuarine systems are affected by human use and development of both coastal land and the surrounding water. One consequence of this use is the deterioration of water quality, which can lead to changes in community structure and a loss of species richness. Another effect of increased usage of marine water ways in the introduction of invasive species. These non-natives also have the ability to change community structure and reduce ecosystem services. In particular cnidarians are able to thrive in degraded systems in part owing to their ability to tolerate low levels of dissolved oxygen and their bipartite life-history. Cnidarians are also easily transported long distances often through commercial shipping and aquaculture.

New Jersey waters have seen large populations of nuisance and invasive cnidarian species in recent years. In the past few years there have been two documented hydrozoan invasions into New Jersey estuaries. Moerisia sp. polyps were collected on settling plates from Barnegat Bay, New Jersey deployed in 2014. These polyps were identified molecularly using universal cnidarian primers for the 16S mitochondrial locus. This was the first description of this species, a known invasive, in New Jersey waters. Another invasive species found in New Jersey and documented in 2016 is Gonionemus vertens, a known invasive native to the North Pacific, with populations that occur along the East Coast of the United States. In order to determine if this population was an expansion of those found in New England or a unique invasion, individuals were collected from two locations in Connecticut, one location in Massachusetts, one location in France, and from the only known New Jersey population. These individuals were analyzed at both the 16S and COI mitochondrial loci, from these sequences Neighbor-joining trees were created. These trees suggest that the New Jersey population is more closely related to the French/Mediterranean population than any of those from New England.

With populations of hydrozoans increasing and invasive species entering systems continually, the need for effective management strategies is critical. Aeolid nudibranchs are one of only a few known cnidarian predators and present a unique opportunity for studying what species of cnidarians they are consuming, as they retain the cnidocysts of their prey. Exploiting this unique ability, total DNA was extracted from nudibranchs collected on settling plates from Barnegat Bay, New Jersey in 2014. Using cnidarian specific primers for the 16S mitochondrial locus and primers specific for Chrysaora chesapeakei (a common nuisance species in these waters), it was determined that aeolid nudibranchs in this system are consuming cnidarian polyps of both C. chesapeakei and the invasive Moerisia sp. This technique can also be used as a mechanism for locating cryptic cnidarian polyps, which is important as the polyp stage is the most critical in producing persistent populations of cnidarian species.

Therefore, this dissertation explores the ability of molecular ecology to contribute to the management of nuisance and invasive species in marine and estuarine systems.

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