Table of Contents

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

M. californianus Conrad, 1837 were obtained from Cattle Point on San Juan Island, WA (48°26'59.6811"N, 122°57'51.9358"W). M. trossulus and M. galloprovincialis were obtained from a commercial supplier (Penn Cove Shellfish, Coupeville, WA, USA; 48°13'06.5579" N, 122°42'25.4331"W). The mussels were maintained in seatables (66 × 135 × 32 cm) with a constant flow of seawater at the Friday Harbor Laboratories (48°32'45.7249" N, 123°00'46.9262"W). Mussels were fed twice daily with a total of approximately 10 mL of Shellfish Diet 1800 TM (Reed Mariculture, Campbell, CA, USA).

Aquatic respiration rates were measured in a closed, recirculating flow chamber of 1-liter capacity.  The transparent acrylic test chamber (15 cm × 5 cm × 5 cm, L × W × H) was connected to a submersible pump (360 GPH, Model 25D, Rule Industries, Gloucester, MA, USA) via PVC pipe (25.4 mm i.d.) and custom machined high-density polyethylene connector fittings. The water-tight test chamber was filled with artificial seawater (32 PSU; Instant Ocean; Spectrum Brands, Blacksburg, VA) and submersed in a temperature-controlled water bath (50 L). The water bath's temperature was maintained using a programmable, recirculating water heater/chiller (±0.005°C; AP07R-20-A11B, Polyscience, Niles, IL, USA).  Trials were run at water velocities were estimated along the centerline of the testing chamber by tracking the displacement of glass microbeads at each flow setting (mean particle diameter 9 μm, density 2.0 g cm⁻³; Potters Industries, Malvern, PA, USA).  

Oxygen concentrations were measured with non-intrusive fiber-optic fluorescence-based optodes and sensor spots on the inner surface of the chamber (FireSting Pro; OXSP5 and TPSP5 spots, Pyroscience, Aachen, DEU). Samples were recorded at a rate of 1 Hz and drift of the O2 probe was negligible (e.g., <0.1% over 2 h at 20°C).

Each trial involved positioning individual mussels along the centerline of the chamber and subsequently measuring the organism's oxygen usage at stable temperatures of 5, 11, 17, 23, and 29°C. Trials were run for 2 h, ensuring that a stable rate of decline could be identified. After each trial, all soft tissues were dried for 72 hours at 60°C (Lindeberg/Blue M Vacuum Oven; ThermoScientific Inc., Waltham, MA, USA), and weighed using an analytical balance (0.001 g; PA153 Pioneer Analytical Balance; Ohaus Corp., Pine Brook, NJ, USA).  

All analyses were conducted in R (ver. 4.4.2; RStudio 2024.12.0 (build 467). The R package respR was used to analyze the respiration data (Harianto, 2019). Respiration rates were standardized by the dry biomass of the mussels.

* Data table within submitted file "Mussel_respiration_data.csv" was imported into the BCO-DMO data system for this dataset.  Table will appear as Data File: 953833_v1_mussel-respiration-rates.csv (along with other download format options).

* Metadata extracted from methodology and added to table mussel_collection_information.csv including geospaital bounds (in decimal degrees), site information, and a lookup table for the species code used in the dataset matched to the full Scientific Name (authority) and LSID.

* LSIDs added for taxonomic names used in the metadata using the world register of marine species on 2025-02-20.

NSF Award Abstract:
The project investigates how the metabolic activity of dense aggregations of marine organisms alter the water chemistry of their interstitial spaces, and how these microscale alterations feedback to affect the organisms’ interactions in coastal ecosystems. The research team focuses on bivalve mussels, foundation species that form dense ‘beds’ typically known for facilitating other species by ameliorating harsh flow conditions. This ability can become a liability, however, if flow is not sufficient to flush the interstitial spaces and steep, metabolically-driven concentration gradients develop. The research evaluates whether corrosive chemical microclimates (such as low oxygen or low pH) are most extreme in low flow, high temperature conditions, especially for dense aggregations of mussels with large biomass and/or high respiration rates, and if they negatively impact mussel beds and the diverse biological communities they support. The research addresses a global societal concern, the impact of anthropogenic climate change on coastal marine ecosystems, and has potential applications to aquaculture and biofouling industries by informing adaptation strategies to “future-proof” mussel farms in the face of climate change and improved antifouling practices for ships, moorings, and industrial cooling systems. The project forges new collaborations with investigators from three campuses and integrates research and education through interdisciplinary training of a diverse group of graduate, undergraduate and high school students. STEM education and environmental stewardship is promoted by the development of a K-12 level science curriculum module and a hand’s-on public exhibit of bivalve biology at a local shellfish farm. Research findings are disseminated in a variety of forums, including peer-reviewed scientific publications and research presentations at regional, national and international meetings.

The research team develops a framework that links environmental conditions measured at a coarse scale (100m-100km; e.g., most environmental observatories) and ecological processes at the organismal scale (1 cm – 10 m). Specifically, the project investigates how aggregations of foundation species impact flow through interstitial spaces, and how this ultimately impacts water chemistry immediately adjacent to the organisms. The research focuses on mytilid mussels, with the expectation that the aggregation alters the flow and chemical transport in two ways, one by creating a physical resistance, which reduces the exchange, and the other by enhancing the exchange due to their incurrent/excurrent pumping. These metabolically-driven feedbacks are expected to be strongest in densely packed, high biomass aggregations and under certain ambient environmental conditions, namely low flow and elevated temperature, and can lead to a range of negative ecological impacts that could not be predicted directly from coarse scale measures of ambient seawater chemistry or temperature. The team develops computational fluid dynamic (CFD) models to predict interstitial flows and concentration gradients of dissolved oxygen and pH within mussel beds. The CFD model incorporates mussel behavior and physiological activity (filtration, gaping, respiration) based on published values as well as new empirical work. Model predictions are compared to flow and concentration gradients measured in mussel aggregations in the laboratory and field. Finally, the team conducts several short-term experiments to quantify some of the potential negative ecological impacts of corrosive interstitial water chemistry on mussel aggregations, such as reduced growth, increased dislodgement, increased predation risk, and reduced biodiversity. Because the model is based on fluid dynamic principles and functional traits, the framework is readily adaptable to other species that form dense assemblages, thereby providing a useful tool for predicting the ability of foundation species to persist and provide desirable ecosystem services under current and future multidimensional climate scenarios.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.