Effect of temperature and elemental concentration on the chemical composition of percid otoliths.
Paris Collingsworth, Ph.D. student, Jason J. Van Tassell, Ph.D. student, and Elizabeth A. Marschall. Funded by: Ohio Lake Erie Commission, Lake Erie Protection Fund and NOAA, Interjurisdictional Fisheries Act.

Although otolith microchemistry is becoming a popular tool of freshwater fishery ecologists interested in tracking location history of fish, we are recognizing some limits in our understanding of the elemental uptake process. For this technique to be successful, an uptake relationship must exist between elemental concentration in the environment (i.e., water elemental concentration) and resultant elemental concentration in the otolith. Although this relationship has been shown for marine and estuarine fish in both field and laboratory studies with a variety of species, the relationship is not well documented for freshwater fish species. The uptake rate of elements from the water into the otolith is not instantaneous. A certain length of time is needed before the element concentration within the otolith stabilizes to the element available in the water. Abiotic factors, such as salinity and temperature, are known to influence elemental uptake rates, particularly for strontium. While it is likely that such relationships exist in freshwater, the exact influence of temperature has yet to be established. Because elemental concentrations are lower in freshwater systems than in marine systems and because physiology of freshwater fish differs substantially from marine fish, we cannot rely on previously established findings from marine studies. We will perform a series of laboratory experiments to estimate uptake rates of trace elements for both walleye and yellow perch.

Our experiments will determine the influence of time, temperature, and elemental concentration of the water on otolith microchemistry. Our ultimate goal is to apply the results of these experiments to concurrent studies in which otoliths from wild fish captured at a given location and a given time are analyzed to determine where those fish lived previously. Because of our incomplete understanding of the interaction between environmental elemental concentration and temperature on the ultimate elemental concentration of an otolith, we risk ambiguity in assigning sources to fish in these studies. Lake Erie spawning and larval-rearing habitats experience a range of temperatures among locations at a given time and within locations over a season. As such, we expect the problem of temperature to be important in these studies.

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Paris Collingsworth's page

Paris can be emailed at collingsworth.8 "at" osu.edu

Jason Van Tassell''s page

Jason can be emailed at van-tassell.1 "at" osu.edu

Cross section of a juvenile yellow perch otolith.

Technician Tyler Groll cleaning the experimental tanks.

Larval yellow perch otolith with daily growth rings.

Experiment 1

Our first experiment, conducted during the summer of 2004, will answer the following objectives.

1. Determine Sr uptake relationship by relating water concentration of Sr to the resulting concentration in the otolith by laser ablation and inductively coupled plasma mass spectrometry (LA-ICPMS).

2. Determine uptake rate (the length of time for an element concentration to stabilize within the otolith) to reach the stable Sr relationship by LA-ICPMS that was determined in objective 1.

3. Compare Sr uptake relationship and uptake rate (Objective 1 and 2) determined by LA-ICPMS with results determined by solution based and inductively coupled plasma mass spectrometry (SO-ICPMS).

Juvenile walleye and yellow perch were obtained from the St. Marys State Fish Hatchery, Ohio Department of Natural Resources, in May 2004 and transported to the wetlab facilities of the AEL. For both walleye and yellow perch, we had two replicates of each of the two strontium (Sr) levels (control concentration: native Sr concentration (230 µg/L) of AEL water supply and treatment concentration: 600 µg/L by diluting Sr in AEL water). Temperature was maintained at 14° C. We collected water samples every two days to monitor elemental conditions within the tanks.

On days 1, 3, 5, 7, 10, 15, 20, and 30 (yellow perch only), we sampled a combined total of 5 fish from the two walleye treatment tanks and the two walleye control tanks and 5 fish from each yellow perch tank. On the final day of the experiment (day 20 for walleye and day 30 for yellow perch), we removed all fish remaining in each tank. All sampled fish were measured and weighed. Sagittal otoliths were extracted under a dissecting microscope, mounted in resin, and sectioned. All elemental analyses are being performed by the Microscopic and Chemical Analysis Research Center (MARC) located at The Ohio State University. The isotopes being measured are ⁴⁶Ca, ⁴⁸Ca, ⁸⁶Sr, ⁸⁷Sr, and ⁸⁸Sr. We will complete water and otolith analyses by this fall.

Experiment 2

Our second experiments, to be conducted during summer 2005 and 2006, will address the following objectives.

1. Determine the influence of temperature, water elemental concentration, and their interaction on otolith microchemistry

2. Compare the effects of temperature and water elemental concentration in two commercially important percid species, walleye and yellow perch.

Juvenile walleye and yellow perch will be obtained from the St. Marys State Fish Hatchery, Ohio Department of Natural Resources, in June 2005 and 2006 and the experiments will be conducted at the wetlab facilities of the AEL. We will use a factorial design with two replicates of each of two levels of elemental concentrations (strontium (Sr) 300 and 1200 µg/L, barium (Ba) 35 and 70 µg/L, magnesium (Mg) 20 and 40 mg/L, and manganese (Mn)10 and 20 µg/L) crossed with three temperatures (10, 15, and 20°C), representing a range of expected conditions in Lake Erie and its tributaries. Water spikes will be prepared by adding appropriate amounts of SrCl₂, BaCl₂, MgCl₂ · 6H₂O, and MnCl₂ · 4H₂O to AEL water. Water samples will be collected three times per week during the duration of the experiment to monitor elemental conditions within the tanks.

Fish will be maintained under experimental conditions for 45 days, after which, all surviving fish will be measured, weighed, and their otoliths removed and kept for chemical analyses. All elemental analyses will be performed by the Microscopic and Chemical Analysis Research Center located at The Ohio State University. Otoliths and water samples will be analyzed for chemical composition by inductively coupled plasma mass spectrometry (ICPMS) using a ThermoFinnigan Element 2 Inductively Coupled Plasma Sector Field Mass Spectrometer. Trace element deposition into otoliths will be measured spatially on the otoliths using a 193-nm Excimer ArF laser. The isotopes that will be sampled are ¹³⁷Ba, ¹³⁸Ba, ⁴⁶Ca,

Tanks set up in one of the environmental chambers.