Participants
Joseph Eastman
I am an anatomically oriented ichthyologist and I work exclusively on Antarctic fishes. I study their biology in a historical and phylogenetic context. Thus my research attempts to answer a series of questions relating to the nature of Antarctic fish diversity. Since diversification in buoyancy is the hallmark of the notothenioid radiation, I am interested in how species with reduced density evolved from ancestors who were heavy bottom dwellers. Or phrased in another way, how much morphological and ecological diversification has accompanied phylogenetic diversification in various notothenioid groups? I also study other aspects of notothenioid biology. For example, is novel brain and sense organ morphology required for fish to live in the subzero waters of the Antarctic shelf? Are notothenioids an example of a species flock such as those found in other isolated habitats like rift lakes and remote islands?
What I hope to accomplish on the ICEFISH 2004 cruise
My specific goals for the ICEFISH cruise are these.
- Obtaining measurements of buoyancy for as many notothenioid species as possible, especially from species of the phyletically basal families Bovichtidae, Eleginopidae and representatives of the nototheniid genera Patagonotothen, Paranotothenia and Dissostichus. I am especially interested in species like the Patagonian toothfish (“Chilean sea bass’), Dissostichus eleginoides, where every ontogenetic phase has a different feeding spectrum on the shelf, slope and bathyl waters around the Falklands. Are there corresponding changes in buoyancy? This is a commercially exploited species so this information is of practical value.
- Perfusion and fixation of notothenioid brain and sense organs for study of gross and microscopic anatomy in an ecological and phylogenetic context. The basic questions are these. Does a unique habitat require novel brain and sense organ morphology? Does neural and sensory diversification accompany habitat diversification in various notothenioid clades? Are there convergent neural adaptations to Antarctic habitats among phyletically unrelated fishes? Will knowledge of brain morphology contribute to resolution of the doubts about the phyletic position of bovichtids among basal notothenioids?
- Documentation of fish biodiversity and possible discovery and description of unknown species in the vicinity of Bouvet Island and the seamounts north of Bouvet. The CCAMLR Statistical Subarea 48.6, centered on Bouvet Island, is one of the largest subareas in the Southern Ocean and is infrequently visited and the fish fauna is poorly known. It is 1,380 km from the Antarctic continent and sometimes considered a separate biogeographic province. A brief survey in 1980 reported only five species of notothenioids but this is certainly attributable to limited and incomplete sampling. It is important to remedy this gap in our knowledge because commercial fishing will soon be targeting this area.