Investigating Feeding by Naupliar Copepods in Resurrection Bay Gulf of Alaska

Author: Jennifer Staat

Faculty Supervisor: Michelle Jungbluth

Department: Biology

Copepod nauplii are a critical food source for culturally and commercially important fishes during their larval stages. In the Gulf of Alaska, due to harsh conditions during the time nauplii tend to be abundant and challenges in the identification of species, little is known about the role of nauplii in Alaskan food webs. This study aims to gain a better understanding of feeding by the nauplii and how their diets change over the course of the winter-spring transition in Resurrection Bay. Using DNA-based methods, we will characterize the prey assemblages and diets of copepod nauplii from January to March in Resurrection Bay, Alaska. We will perform dietary DNA analysis (dDNA) alongside environmental DNA (eDNA) of prey in collected water samples to compare diets to prey available using high-throughput DNA sequencing targeting the 16S rRNA and 18S rRNA genes for prokaryotic and eukaryotic prey, respectively. We will use species-specific PCR assay targeting the mtCOI gene to identify at least three dominant nauplii from the calanoid copepod species; Neocalanus flemingeri, Neocalanus plumchrus, and Calanus marshallae and compare dDNA between species and how diets change over time. SSPCR has helped us identify shifts in the assemblage of nauplii over the course of the transition. Early in the study appears dominated by N. flemingeri (100% of calanoid nauplii measured in January). These assemblages appear to transition to C. marshallae closer to the bloom in March (50-100% of calanoid nauplii measured). Ultimately, identifying temporal patterns in naupliar feeding leading up to and during the spring bloom will help us understand the extent to which the nauplii are adapted to changing food conditions. Understanding the diets of copepod nauplii during such shifts within the phenology of the spring bloom can also have potential implications on higher trophic levels that rely on nauplii as a primary food source.