SEGH Articles

Otoliths: The little “White” box recorders of the fish world

01 February 2013
The use of fish otolith (ear bone) microchemistry has enabled scientists understand better fish migratory patterns and stock identification

 

Andy Marriott is in his final year studying for a PhD in the use of biogeochemical tags (primarily otoliths) to determine the origins and movement patterns of fishes. This NERC-funded research project at Bangor University, North Wales is supervised by Dr. Ian McCarthy and Prof. Chris Richardson of the School of Ocean Sciences at Bangor University, Dr Simon Chenery at the British Geological Survey and Dr Mike Armstrong (Case partner) from the Centre for Environment, Fisheries and Aquaculture Science.

 

Since graduating from Bangor University in 2007 where Andy studied the population biology of the red gurnard (Chelidonichthys cuculus) in inshore waters of Eastern Anglesey his interest in fish otoliths, or ear stones as they are more commonly known, has grown. Otoliths are paired calcified structures, situated in semi-circular canals either side of the brain and are used by the fish as auditory and/or balance organs. Their use as indicators in identifying the age of fish has been well documented with the first observations of otolith growth increments “annuli” by Reibisch in 1899. These annuli grow throughout the life of the fish creating banding patterns and can be a reliable way of estimating daily, weekly, monthly and yearly growth patterns. However, it is their use as an environmental recorder and biogeochemical tag which has accelerated the use of these metabolically inert structures during the last decade. The use of otolith microchemistry has enabled scientists to get a better understanding of fish migratory patterns, stock identification and the detection of Diadromy (fish moving between fresh and marine waters) with the reconstruction of temperature and salinity histories.

Variations observed in the chemical composition of fish otoliths, such as changes in trace elements incorporated within the otolith matrix, has enabled the discrimination between the life histories of fish species which spend some part of their life residing in water bodies which differ in their chemical composition. For example, moving between marine and freshwater (in either direction), or moving between bodies of water in either the marine or freshwater environment with distinct (natural or anthropogenic) water chemistry. These elemental tags may provide valuable information on movement patterns of larval and juvenile fish, may enable the identification of distinct “groups” of fish based on spawning or nursery location and allow the study of connectivity and habitat utilisation in fish populations.

Working with the BGS, one part of Andy’s PhD project has been to examine whether otolith microchemistry can be used to identify the rivers of origin of juvenile brown trout parr (Salmo trutta) collected from 36 rivers in NW England, Wales, Isle of Man, SW Scotland and the east coast of Ireland which drain into the Irish Sea. The ultimate aim of this research being to determine whether river- or region-specific chemical tags exist in the otoliths which may be used to identify sea-caught sea trout (the form of S. trutta that migrates to sea to feed) back to their region or river of origin.

Otoliths removed from trout parr have been analysed using solution-based inductively-coupled plasma mass spectrometry (sb-ICP-MS) to measure the element: Ca ratios of Mg, Mn, Sr and Ba and data analyses are currently underway to determine whether these biogeochemical tags can be used to classify the trout parr back to source. Relating the otolith chemical tag in a given catchment to the underlying geological bedrock formations and water chemistry may also assist in our understanding of why the trout parr are being classified back to particular locations. “Otoliths may be acting as little “white box recorders” of the entire life history of the fish with the differences in ambient water and various environmental conditions experienced by the fish all stored within the calcified structures. The exciting bit is trying to untangle the secrets held within the otoliths to tell us the life story of that fish”.

 

Future work involving the analysis of otoliths collected from adult sea trout may allow the identification of those adults back to their regions (or even rivers) of origin using the chemical tags identified in the juvenile trout parr. The validity of using trace elements as biogeochemical tags found within fish otoliths of brown trout parr may also assist in future conservation and management planning for this species.

Andy Marriott, Andrew.lewis.marriott@gmail.com 

Nuffield Fish Laboratory, Bangor University, UK.

 

  

References:

Marriott, A. L., Latchford, J. W. and McCarthy, I. D. 2010. Population biology of the red gurnard (Aspitrigla cuculus L.; Triglidae) in the inshore waters of Eastern Anglesey and Northwest Wales. Journal of Applied Ichthyology. 26, 504-512.

http://onlinelibrary.wiley.com/doi/10.1111/j.1439-0426.2010.01455.x/full?globalMessage=0

Keep up to date

SEGH Events

Submit Content

Members can keep in touch with their colleagues through short news and events articles of interest to the SEGH community.

Science in the News

Latest on-line papers from the SEGH journal: Environmental Geochemistry and Health

  • Assessment of the toxicity of silicon nanooxide in relation to various components of the agroecosystem under the conditions of the model experiment 2018-08-18

    Abstract

    Investigation of SiO2 nanoparticles (NPs) effect on Eisenia fetida showed no toxic effect of the metal at a concentration of 250, 500 and 1000 mg per kg of soil, but conversely, a biomass increase from 23.5 to 29.5% (at the protein level decrease from 60 to 80%). The reaction of the earthworm organism fermentative system was expressed in the decrease in the level of superoxide dismutase (SOD) on the 14th day and in the increase in its activity to 27% on the 28th day. The catalase level (CAT) showed low activity at average element concentrations and increase by 39.4% at a dose of 1000 mg/kg. Depression of malonic dialdehyde (MDA) was established at average concentrations of 11.2% and level increase up to 9.1% at a dose of 1000 mg/kg with the prolongation of the effect up to 87.5% after 28-day exposure. The change in the microbiocenosis of the earthworm intestine was manifested by a decrease in the number of ammonifiers (by 42.01–78.9%), as well as in the number of amylolytic microorganisms (by 31.7–65.8%). When the dose of SiO2 NPs increased from 100 to 1000 mg/kg, the number of Azotobacter increased (by 8.2–22.2%), while the number of cellulose-destroying microorganisms decreased to 71.4% at a maximum dose of 1000 mg/kg. The effect of SiO2 NPs on Triticum aestivum L. was noted in the form of a slight suppression of seed germination (no more than 25%), an increase in the length of roots and aerial organs which generally resulted in an increase in plant biomass. Assessing the soil microorganisms’ complex during introduction of metal into the germination medium of Triticum aestivum L., there was noted a decrease in the ammonifiers number (by 4.7–67.6%) with a maximum value at a dose of 1000 mg/kg. The number of microorganisms using mineral nitrogen decreased by 29.5–69.5% with a simultaneous increase in the number at a dose of 50 mg/kg (+ 20%). Depending on NP dose, there was an inhibition of the microscopic fungi development by 18.1–72.7% and an increase in the number of cellulose-destroying microorganisms. For all variants of the experiment, the activity of soil enzymes of the hydrolase and oxidoreductase classes was decreased.

  • Seasonal characteristics of chemical compositions and sources identification of PM 2.5 in Zhuhai, China 2018-08-16

    Abstract

    Fine particulate matter is associated with adverse health effects, but exactly which characteristics of PM2.5 are responsible for this is still widely debated. We evaluated seasonal dynamics of the composition and chemical characteristics of PM2.5 in Zhuhai, China. PM2.5 characteristics at five selected sites within Zhuhai city were analyzed. Sampling began on January 10, 2015, and was conducted for 1 year. The ambient mass concentration, carbon content (organic and elemental carbon, OC and EC), level of inorganic ions, and major chemical composition of PM2.5 were also determined. Average concentrations of PM2.5 were lower than the National Ambient Air Quality Standard (NAAQS) 24-h average of 65 μg/m3. The daily PM2.5 concentration in Zhuhai city exhibited clear seasonal dynamics, with higher daily PM2.5 concentrations in autumn and winter than in spring and summer. Carbon species (OC and EC) and water-soluble ions were the primary components of the PM2.5 fraction of particles. Apart from OC and EC, chemical species in PM2.5 were mainly composed of NH4+ and SO42−. There was a marked difference between the summer and winter periods: the concentrations of OC and EC in winter were roughly 3.4 and 4.0 times than those in summer, while NH4+, SO42−, NO3, and Na+ were 3.2, 4.5, 28.0, and 5.7 times higher in winter than those in summer, respectively. The results of chemical analysis were consistent with three sources dominating PM2.5: coal combustion, biomass burning, and vehicle exhaust; road dust and construction; and from reaction of HCl and HNO3 with NH3 to form NH4Cl and NH4NO3. However, additional work is needed to improve the mass balance and to obtain the source profiles necessary to use these data for source apportionment.

  • Estimates of potential childhood lead exposure from contaminated soil using the USEPA IEUBK model in Melbourne, Australia 2018-08-14

    Abstract

    Soils in inner city areas internationally and in Australia have been contaminated with lead (Pb) primarily from past emissions of Pb in petrol, deteriorating exterior Pb-based paints and from industry. Children can be exposed to Pb in soil dust through ingestion and inhalation leading to elevated blood lead levels (BLLs). Currently, the contribution of soil Pb to the spatial distribution of children’s BLLs is unknown in the Melbourne metropolitan area. In this study, children’s potential BLLs were estimated from surface soil (0–2 cm) samples collected at 250 locations across the Melbourne metropolitan area using the United States Environmental Protection Agency (USEPA) Integrated Exposure Uptake Biokinetic (IEUBK) model. A dataset of 250 surface soil Pb concentrations indicate that soil Pb concentrations are highly variable but are generally elevated in the central and western portions of the Melbourne metropolitan area. The mean, median and geometric soil Pb concentrations were 193, 110 and 108 mg/kg, respectively. Approximately 20 and 4% of the soil samples exceeded the Australian HIL-A residential and HIL-C recreational soil Pb guidelines of 300 and 600 mg/kg, respectively. The IEUBK model predicted a geometric mean BLL of 2.5 ± 2.1 µg/dL (range: 1.3–22.5 µg/dL) in a hypothetical 24-month-old child with BLLs exceeding 5 and 10 µg/dL at 11.6 and 0.8% of the sampling locations, respectively. This study suggests children’s exposure to Pb contaminated surface soil could potentially be associated with low-level BLLs in some locations in the Melbourne metropolitan area.