Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
  • BCO-DMO Processing Description
  • Problem Description
• Related Publications
• Related Datasets
• Parameters
• Instruments
• Project Information
• Funding

Fish collection locations and associated information are found in an accompanying dataset for this project: https://www.bco-dmo.org/dataset/916418.

Otolith element concentrations for each individual fish were measured at the University of Austin, Jackson School of Geosciences using laser ablation inductively coupled mass spectrometry (LA-ICP-MS). Standard reference materials included a National Institute of Standards and Technology glass standard (NIST-612) and a United States Geological Survey microanalytical carbonate standard pressed pellet (MACS-3). Otolith element concentrations were quantified along the longest dorso-ventral axis spanning the core (i.e., hatch) to the edge (i.e,. death). The distance measurement indicates the distance of the laser spot as it progressed from the beginning of the transect near the otolith core (a distance of zero) and progressively moving outward to the outer edge of the ototlith.

Analytical methods followed the detailed methods provided in Altenritter et al. (2018) and Altenritter and Walther (2019).

Data were corrected using certified reference materials and converted to parts per million (ppm) concentrations. 

- Imported fish collection location data (file "916418_v2_fish_collection_locations.csv").
- Imported original file "NSF FishOtolithTransects Combined.xlsx" into the BCO-DMO system.
- Flagged "NAN" as a missing data value (missing data are empty/blank in the final CSV file).
- Added the following columns from the fish collection location data file to this dataset by joining on Fish_ID: Station_Latitude, Station_Longitude, Date_Collected, Species.
- Renamed fields to comply with BCO-DMO naming conventions.
- Saved the final file as "962569_v1_otolith_transects.csv".

NSF Award Abstract:
Ocean oxygen loss (deoxygenation) is increasing due to climate warming. This warming, together with nutrient loading, is causing many marine and freshwater systems to experience increasing episodes of hypoxia (low oxygen) of greater duration and intensity. Impacts on fish and fisheries have been difficult to quantify; direct observation has been challenged by a lack of long-term exposure indicators. This team has successfully refined the use of fish chemical biomarkers in fish otoliths (earstones) to directly assess lifetime hypoxia exposure in fishes. This project will those findings to look for additional biomarkers and models, to expand our understanding of how hypoxia affects fish and their food webs, contaminant transfers, and ecosystem services including economic impacts. The project includes a unique way of training students in science communication, posing the question: What forms of media and "messaging strategies" about deoxygenation are most effective at raising public awareness and understanding? Students are developing entries for PlanetForward's Storyfest, which is a contest to tell compelling stories to foster environmental understanding and solutions. Students from historically underrepresented, economically disadvantaged backgrounds are particularly sought out to participate. The investigators will engage with regional, national, and international management agencies and other relevant stakeholder groups to share information.

This project encompasses a novel, linked set of interdisciplinary studies of food webs, and ecosystem services assessment. The thematic questions explored in this project are: 1. How does hypoxia alter habitat use for fishes? 2. How does hypoxia-altered habitat use and habitat productivity change food webs? 3. How does hypoxia affect/enhance trophic transfer of methylmercury? 4. How do hypoxia-induced changes in food webs affect aquatic ecosystem services? The set of linked studies will employ chemical analyses of otoliths and eye lenses, combined with chemical analyses of muscle tissues (Questions 1 and 3), physiologically-structured food web modeling informed by monitoring time-series (Questions 2 and 4), and a scoping workshop to address ecosystem services (Question 4). The investigators are using a "trans-basin" comparative approach to system-specific responses, studying fishes in Lake Erie, the Baltic Sea, and a Gulf of Mexico estuary. They study three species from each system that represent different degrees of benthic reliance, to discern differential responses to the increasingly hypoxic environment. This research provides novel insight about variable biotic responses to oxygen loss and the impacts on ecosystem functioning.