Date of Completion


Embargo Period



Leocadio Blanco-Bercial, George McManus, David Richardson

Field of Study



Master of Science

Open Access

Open Access


Zooplankton occupy pivotal positions in pelagic ecosystems and have direct impacts on trophic dynamics on continental shelves. Time-series records of zooplankton species diversity, distribution, and abundance are needed to understand, document, and predict impacts of environmental conditions on pelagic ecosystems. This study focuses on species of the calanoid copepod genus Pseudocalanus on the NW Atlantic continental shelf. Time-series analysis was conducted on the distribution and abundance of Pseudocalanus spp. and of two co-occuring cryptic species from 1977-2012 and 1995-2012 respectively, based on data from Ecosystem Monitoring (EcoMon) surveys by the NOAA-NMFS Northeast Fisheries Science Center and the US GLOBal Ocean ECosystem Dynamics (US GLOBEC) surveys on Georges Bank. Analysis and mapping of abundance anomalies during May-June showed that depth-averaged temperature and salinity were not strongly correlated with Pseudocalanus spp. abundance in the Georges Bank region. Real-time quantitative PCR (qPCR) was used to discriminate the cryptic species, P. moultoni and P. newmani, in samples collected on Georges Bank from 1995 to 2012. Time-series analysis of the individual species abundances and abundance anomalies, with comparative analysis of depth-averaged temperature, salinity, and other environmental variables, provided evidence of species-specific differences. This study demonstrated that closely-related, cryptic species may have different responses to environmental variation and change. Time-series analysis and mapping of species-specific abundances yielded new understanding of the underlying causes of time/space variation in these populations. Accurate resolution of species diversity is needed to improve predictions of the responses of zooplankton populations and pelagic ecosystems to variability and climate change.

Major Advisor

Ann Bucklin