Overview. Marine zooplankton show strong ecological responses to climate change, but little is known about their capacity for evolutionary response. Many authors have assumed that the evolutionary potential of zooplankton is limited. However, recent studies indicate broad circumstantial evidence for the idea that selection is a dominant evolutionary force acting on these species, and that genetic isolation often is achieved at regional spatial scales in pelagic habitats. The proposed research will use a combination of population genetic, ecological, and oceanographic techniques to test two central hypotheses regarding how the pelagic environment controls genetic variation within zooplankton species.
This RAPID project will take advantage of a unique opportunity for basin-scale transect sampling across boreal-temperate, subtropical and tropical waters of the Atlantic Ocean (> 90° latitude) through the Atlantic Meridional Transect (AMT) cruise in 2014. Population genomic studies on this material will use RADSeq-derived SNP markers to identify the geographic location of strong genetic breaks within three copepod species, and Bayesian and coalescent analytical techniques will test if these regions act as dispersal barriers. The physiological condition of animals collected in distinct ocean habitats will be assessed by measurements of egg production as well as body size (condition index), dry weight, and carbon and nitrogen content. We will test the prediction that ocean regions that serve as dispersal barriers for marine holoplankton are areas of poor-quality habitat for the target species. We hypothesize that this is a dominant mechanism driving population genetic structure in oceanic zooplankton.
EAGER: New molecular methods for studying copepod nauplii in the field
Investigators: Erica Goetze (PI), Petra Lenz (co-PI), and Karen Selph (co-PI).
The most abundant metazoans in the open sea are often the earliest developmental stages of copepods, their nauplii. Nauplii remain under-studied due to the limitations of conventional techniques and an historical emphasis on studying the larger mesozooplankton. However, there is increasing recognition that nauplii play important roles in food web dynamics, and considerable evidence suggests that nauplii may be important trophic intermediaries between microbial and classical food webs, due to their high abundance, high weight-specific ingestion rates, and ability to feed on relatively small particles. This team of investigators is developing a novel molecular approach to studying diverse populations of nauplii in mixed field samples based on quantitative PCR (qPCR). Here we propose to complete development and validation of this qPCR-based technique for enumeration of nauplii, and demonstrate its utility in the field. The specific objectives of this research are to identify and reduce technical and biological sources of error, determine the accuracy of the method across a range of environmental conditions, and complete one paired field experiment that compares the grazing impact of naupliar and protozoan micro-grazers in a model subtropical coastal ecosystem, in order to demonstrate the utility of this new method.
Environmental DNA biodiversity surveys across the abyssal seafloor in the CCZ
Investigators. Erica Goetze (PI) and Craig R. Smith (co-PI). Funded by Pew Charitable Trusts
Rationale. The first large-scale deep-sea mining is likely to occur in the Clarion-Clipperton Zone (CCZ), a region of particularly valuable mineral resources (nickel- and copper-rich manganese nodules) in the abyssal equatorial Pacific (Wedding et al. 2013, 2015). Approximately 30% of the 6,000,000 km2 management area within the CCZ has been allocated for mining claims, with an additional 24% of the area placed in nine ‘Areas of Particular Environmental Interest’ (APEIs) (each 400km x 400km), protected from mining (Wedding et al. 2013). Given the large areal extent of the CCZ, the regions proposed both for mining and APEIs span a range of physical and biological gradients, including polymetallic nodule density, particulate organic carbon flux and bathymetry, and are host to diverse biological communities (Glover et al. 2002, Smith et al. 2008c, Wedding et al. 2013). Community structure varies both east-west and north-south across the CCZ, with habitat heterogeneity an important contributor to megafaunal community diversity (Amon et al. 2016). Levels of biodiversity and species ranges remain very poorly characterized across the CCZ, making predictions of the impacts of large-scale mining, for example the likelihood of species extinctions, very problematic. To understand and manage the impacts of nodule mining, it is critically important to survey biological community structure and ecosystem function across the entire CCZ region before mining begins. Environmental DNA, or eDNA, surveys provide a new approach to baseline evaluations of biodiversity (e.g., species richness) that could circumvent some of the challenges of comprehensively sampling remote and highly diverse communities in deep ocean habitats. However, eDNA approaches have seen limited application and ground-truthing in marine systems. Research proposed here will execute a comprehensive eDNA study across a range of deep abyssal habitats (abyssal pelagic, abyssal seafloor, seamounts), encompassing both the eastern and western extremes of the CCZ.
Proposed Research. eDNA biodiversity surveys will be conducted for benthic and demersal vertebrate and invertebrate metazoans in the abyssal CCZ. The overarching goal is to test and evaluate the utility of the eDNA approach for biodiversity surveys in the deep sea, and to assemble databases of relevant DNA sequences from diverse deep CCZ habitats and communities in advance of nodule mining.
The specific project objectives are to:
(1)Survey the biodiversity of metazoans, including both invertebrates and vertebrates, in abyssal ecosystems of the Clarion-Clipperton Fracture Zone sampled using eDNA methods.
(2)For the abyssal seafloor and on seamounts, assess seawater, sediment, manganese nodules, and other hard substrates as source material for eDNA faunal surveys to compare and contrast faunal assemblages across these
(3)Conduct comparative studies of eDNA faunal surveys with conventional megafaunal and macrofaunal surveys, using whole-animal collection, morphological identifications and DNA barcoding, as well as larval meroplankton metabarcoding studies, to help evaluate the strengths and limitations of the eDNA approach to quantifying species richness in the abyss.
Exploration of biodiversity and ecosystem structure on seamounts in the western CCZ
Investigators. Jeffrey C, Drazen (PI), Craig R. Smith (co-PI), Erica Goetze (co-PI), Eric Vetter (co-PI). Collaborators: Adrian Glover, Thomas Dahlgren. Funded by NOAA Ocean Exploration