Native fish migrations in the Great Lakes
For the last few years, we have been studying the massive breeding migrations of suckers and other native species into tributaries of the Great Lakes. Almost all of these native migrants are iteroparous, meaning that they breed repeatedly throughout their lives. We are addressing a variety of issues related to the ecology and conservation of these native fish runs, including nutrient subsidies, disease dynamics, contaminant transport, site fidelity and population differentiation, long-term population trends, and fisheries. Past field work has focused on the Upper Peninsula of Michigan. The overall goal of this project is to inspire greater understanding and public appreciation of these remarkable runs, which rival more famous great migrations around the world. This project represents a collaboration with Dave Allan and The Nature Conservancy's Michigan office, and is currently being expanded to include Wisconsin tributaries.
Video: A New Look at Pike. Aired 13 May 2011, Northland Advantures with Dave Carlson
Tanganyika Littoral Ecosystem Project
Lake Tanganyika, the oldest and deepest of the African rift lakes, is a natural wonder under severe threat. I have been studying the fish, snails, and algae of the littoral zone of Lake Tanganyika since 1998. The littoral ecosystem shows a paradoxical combination of nutrient scarcity, globally-high benthic primary productivity, high animal biomass including a diversity of grazing fish and invertebrates, and a complex food web. Understanding the functioning of this system is imperative in order to protect its remarkable biodiversity (>700 endemic animal species) and essential services provided to regional populations (fisheries, clean water, transportation). In collaboration with Yvonne Vadeboncoeur, and supported by the NSF, we are assessing the role that grazing fish play in sustaining ecosystem productivity through nutrient storage, recycling, and new inputs. This project merges organismal and ecosystem perspectives to assess how sensitive this unique system may be to over-fishing and climate change.
Conservation of Native Stream Gobies in the Hawaiian Archipelago
Gobies are prominent members of stream fish communities on tropical islands around the world. Many species of these small fish have evolved from marine ancestors, taking advantage of the opportunities afforded by island streams. However, they retain an obligate marine larval phase, giving rise to a complex life history strategy in which hatching, growth, and breeding all occur in streams but the tiny larvae can disperse among islands (i.e., amphidromy). It is unknown whether populations on different islands have diverged, or instead the species are functionally panmictic. As streams on tropical islands around the globe are becoming increasingly degraded, numerous species of stream gobies are at risk of extinction. In collaboration with Mike Blum and Jim Gilliam, and supported by SERDP, we are analyzing the population structure, demography, and landscape influences upon goby species throughout the Hawaiian archipelago. My group's role in the project is to use trace element fingerprinting in goby otoliths to understand their dispersal strategies and track individual movement between and within islands. We also lead the analysis of stream water quality to assess the effects of land use.
More details about the project: Development and Use of Genetic Methods for Assessing Aquatic Environmental Condition and Recruitment Dynamics of Native Stream Fishes on Pacific Islands (pdf factsheet)
Large-scale Mapping of Biodiversity and Threats
Maps are an essential starting point for large-scale assessment of biodiversity patterns and conservation priorities. We are involved in both global- and regional-scale efforts. At the global scale, we are working on cumulative threat analyses for watersheds that incorporate a wide variety of threat types (in collaboration with many colleagues from the Global Water System Project and DIVERSITAS-Freshwater). We are also synthesizing all available data on biodiversity patterns in large lakes (in collaboration with Yvonne Vadeboncoeur and Jake Vander Zanden), and contributing to a new effort to comprehensively map the global distribution of freshwater biodiversity (GEO BON-Freshwater). At the regional scale, I co-lead the Great Lakes Threat Mapping Project with David Allan and Ben Halpern. This project seeks to merge all existing data on threats to the Laurentian Great Lakes, including chemical pollutants, habitat alteration, invasive species, eutrophication, and over-fishing. Our goal is to generate maps of aggregate threat that can be used to guide either place-based or stressor-based approaches to prioritizing restoration and conservation efforts. This project is particularly timely in light of the unprecedented Great Lakes Restoration Initiative.