Alternative life-history patterns of estuarine fish: barium in otoliths elucidates freshwater residency

2005 ◽  
Vol 62 (5) ◽  
pp. 1143-1152 ◽  
Author(s):  
Travis S Elsdon ◽  
Bronwyn M Gillanders

Elemental concentrations in fish otoliths (earstones) can reconstruct environmental histories of fish if predictable relationships between the environment and elemental incorporation are established. We assessed whether fresh water occupancy of black bream (Acanthopagrus butcheri) can be inferred from otolith barium concentrations (Ba was standardized to calcium (Ca) and expressed as a ratio, Ba:Ca). Otolith Ba:Ca of fish was correlated with ambient Ba:Ca. Using the natural relationships of increasing ambient and otolith Ba:Ca with decreasing salinity, fish from fresh- and salt-water environments were distinguishable. Fish caught in fresh water had approximately double the otolith Ba:Ca of those from salt-water estuaries, for both summer and winter collections. Fish with otolith Ba:Ca ≤5 µmol·mol–1 were classified as resident in salt water, and those with ≥6 µmol·mol–1 as resident in fresh water. Transects of Ba:Ca across fish otoliths classified fish to fresh- or salt-water environments. Fish were identified as having migratory patterns typical of residents, migrants with irregular patterns of diadromy, or migrants with cyclic patterns of anadromomy. Multiple migratory behaviours occurred in fish from the same estuary, indicating far more complex migratory behaviours than were previously known. The application of otolith Ba:Ca to infer freshwater occupancy of fish has rarely been studied, yet may provide more accurate classifications of estuarine environments than strontium (Sr) isotopes and otolith Sr:Ca.

2005 ◽  
Vol 56 (5) ◽  
pp. 609 ◽  
Author(s):  
T. S. Elsdon ◽  
B. M. Gillanders

Elemental concentrations within fish otoliths can track movements and migrations of fish through gradients of environmental variables. Tracking the movements of fish relies on establishing links between environmental variables and otolith chemistry, with links commonly made using laboratory experiments that rear juvenile fish. However, laboratory experiments done on juvenile fish may not accurately reflect changes in wild fish, particularly adults. We tested the hypotheses that: (1) the relationship between ambient (water) and otolith chemistry is similar between laboratory-reared black bream (Acanthopagrus butcheri) and wild black bream; and (2) ontogeny does not influence otolith chemistry. Field-collected and laboratory-reared fish showed similar effects of ambient strontium : calcium (Sr : Ca) on otolith Sr : Ca concentrations. However, ambient and otolith barium : calcium concentrations (Ba : Ca) differed slightly between laboratory-reared and field-collected fish. Importantly, fish reared in stable environmental variables showed no influence of ontogeny on Sr : Ca or Ba : Ca concentrations. Natural distributions of ambient Sr : Ca showed no clear relationship to salinity, yet, ambient Ba : Ca was inversely related to salinity. The distribution of ambient Sr : Ca and Ba : Ca in estuaries inhabited by black bream, suggest that these elements can answer different questions regarding environmental histories of fish. Reconstructing salinity histories of black bream using otolith Ba : Ca concentrations seems plausible, if adequate knowledge of Ba : Ca gradients within estuaries is obtained.


1772 ◽  
Vol 62 ◽  
pp. 90-92 ◽  
Keyword(s):  

The materials necessary for this process are the following; a copper or iron pot of 15 or 20 gallons, an empty cask, some sheet lead, a small jar, a few wood-ashes or soap, and billet-wood for fewel.


2010 ◽  
Vol 66 (2) ◽  
pp. 189-195
Author(s):  
Yuji ITO ◽  
Hideki MIYAMOTO ◽  
Masumi KORIYAMA ◽  
Jiro CHIKUSHI ◽  
Masahiro SEGUCHI

1964 ◽  
Vol 90 (6) ◽  
pp. 97-116
Author(s):  
Norbert L. Ackermann ◽  
Pachern Sridurongkatum

1968 ◽  
Vol 8 (33) ◽  
pp. 491 ◽  
Author(s):  
RW Strickland

A pot trial to assess the effect of salt water on growth and yield of rice in the Northern Territory of Australia was conducted in 1962-63. Two varieties were irrigated with three levels of salinity for varied durations in either the establishment or reproductive phases. Plant emergence was significantly depressed by soil conductivities in excess of 4 m-mhos/cm at 25�C. The restricted use of up to 3000 p.p.m. total soluble salts from 10 days after emergence and of up to 6000 p.p.m. from 20 days after emergence, followed by fresh water, had no effect on flowering time, vegetative or grain yields. The application of 3000 and 6000 p.p.m. total soluble salts in the reproductive phase reduced mean panicle number and grain yield of both varieties and straw yield of one variety. Use of saline water in the establishment phase followed by fresh water and drainage, reduced soil conductivity. In the reproductive phase it nullified the effect of previous fresh water flushing and tended to increase soil conductivity above original levels.


1960 ◽  
Vol 17 (3) ◽  
pp. 295-322 ◽  
Author(s):  
Bertha Baggerman

In juvenile Pacific salmon the changes in salinity preference associated with seaward migration and thyroid activity were studied and used as criteria for the induction of the physiological condition required for migration (migration-disposition).Four species of Oncorhynchus (chum, pink, coho and sockeye) changed preference from fresh to salt water at the onset of seaward migration and maintained this preference throughout the migration season. At the end of this migration period coho and sockeye salmon changed preference from salt to fresh water if retained in fresh water, indicating a re-adaptation to this medium in which they may survive for several years. Chum and pink fry did not show this change in preference and usually died when retained in fresh water. They were apparently unable to re-adapt to this environment.The increasing day length in spring controls the time at which the change in preference from fresh to salt water takes place, and is thus involved in timing the induction of migration-disposition.The photoperiod seems to affect particularly the pituitary-thyroid system. Thyroid activity increases shortly before the onset of migration, remains high during the migration season, and decreases towards its end. The level of thyroid hormone in the blood influences salinity tolerance and preference and, thus, the induction of migration-disposition. Metamorphosis, osmotic "stress" and iodine content of the water may have some additional effect on thyroid activity, but are not the only factors responsible for thyroid hyperactivity during migration.Animals in which migration-disposition has been induced are thought to have become susceptible to appropriate external stimuli "releasing" migration.


1968 ◽  
Vol 25 (8) ◽  
pp. 1591-1602 ◽  
Author(s):  
S. G. Miles

In an experimental apparatus, elvers of the American eel (Anguilla rostrata) showed a stronger positive rheotaxis to fresh water than to salt water. The attractiveness of the fresh water was due to dissolved and particulate organic matter; these components were bio-degradable, heat stable, and nonvolatile. Four streams near Halifax, Nova Scotia, were tested, and were found to differ greatly in their attraction of elvers. Elvers were collected from each of three of these streams, and were not found to be attracted to their own stream water; elvers from one stream gave a greater rheotactic response than elvers from the other streams. The presence of adult eels in the water rendered it more attractive, whereas the presence of elvers made it less so.


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