Increment Formation In Otoliths Research Articles

Comparison of growth rate and formation of otolith increments in age-0 red snapper

Comparison of growth rate and formation of otolith increments in age-0 red snapper

Comparison of growth rate and formation of otolith increments in age-0 red snapper

For wild red snapper Lutjanus campechanus, mean otolith increment deposition rate after marking with oxytetracycline dihydrate (OTC) was daily (0.97 increments day−1) when growth rates were fast (0.63 mm fork length, LF day−1), but were not daily (0.82 increments day−1) when somatic growth was slow (0.2 mm LF day−1). For reared larvae (n=8), increment deposition rates were daily (0.99–1.03 increments day−1), and growth rates ranged from 0.6 to 0.9 mm LF day−1. Growth rate affected increment deposition rate as a threshold function, i.e. when growth rate was <0.3 mm LF day−1, deposition was less than daily, but above this level increment deposition did not exceed a daily rate. As growth rates increased increment widths increased. Examination of a sub-sample (n=8) of the otoliths from the slowest growing wild fish by scanning electron microscopy did not increase increment counts. Because L. campechanus are late spring-early summer spawners, young fish can expect maximum growth due to warm summer temperatures. Thus, daily ageing methods should be well suited to this species.

Increment formation in otoliths of slow-growing winter flounder (&lt;i&gt;Pleuronectes americanus&lt;/i&gt;) larvae in cold water

Increment formation in otoliths of slow-growing winter flounder (&lt;i&gt;Pleuronectes americanus&lt;/i&gt;) larvae in cold water

Increment formation in otoliths of slow-growing winter flounder (Pleuronectes americanus) larvae in cold water

Known-age winter flounder (Pleuronectes americanus) larvae were reared in large outdoor mesocosms where the temperatures were &lt;5°C for the first 40 days and increased slowly after this and in field enclosures where the temperature ranged between 12.3 and 19.6°C. In the cold-water group, somatic and otolith growth were suppressed at the low initial temperatures and no increments were visible. After temperatures increased, somatic growth was evident and a variable number of initial narrow increments (0.2-0.6 µm) was observed. As larvae emerged from this initial period of slow growth, they began to develop rapidly and otolith increment widths increased to 1.0-3.0 µm. In contrast, larvae reared at the warmer temperature grew rapidly and laid down daily increments beginning 5 days after hatching.

Validation of daily increment formation in otoliths for three Diplodus species in the Mediterranean sea,

Validation of daily increment formation in otoliths for three Diplodus species in the Mediterranean sea,

Validation of daily increment formation in otoliths for three Diplodus species in the Mediterranean sea

The efficacy of two fluorochromes, chlorhydrate of tetracycline (CHTC) and alizarin complexone (ALC), to induce a label on the otoliths of juvenile sparid fishes by immersion techniques was tested in different experimental conditions. CHTC did not mark otoliths in natural sea water and was toxic in divalent cation‐free sea water. Immersing fish in a 50‐mg 1−1 ALC natural seawater solution for 24 h induced a well‐defined mark on the otoliths and had no effect on survival. A daily periodicity of increment formation on otoliths was observed in captivity for Diplodus vulgaris and D. puntazzo, and was conserved in natural environment for D. sargus. The frequency of increment deposition did not vary with the age of juvenile fishes. Thus, otolith microstructure analysis will be a reliable method to give age estimates in these three sparid species during their juvenile life.

Early development of the pineal photoreceptors prior to the retinal differentiation in the embryonic rainbow trout, Oncorhynchus mykiss (Teleostei).

The development of the pineal and retinal photoreceptors in the embryonic rainbow trout, Oncorhynchus mykiss was investigated by means of light and electron microscopy. The pineal photoreceptors endowed with photoreceptive outer segments and signal-transmitting synapses appeared first 15 days after fertilization, and well developed by 21 days. In contrast, the retinal photoreceptors appeared as late as 27 days after fertilization (1 day before hatching). This temporal disparity in photoreceptor development has been compared with the photoperiodic formation of otolith increments, which is initiated during an early developmental stage lacking retinal photoreception. It has been suggested that the early development of pineal photoreceptors may be involved in light-dark recognition, establishment of the diel and circadian rhythms, and entrainment to the environmental photoperiod in the embryonic rainbow trout.

The periodicity of primary increment formation in the otoliths of Arctic charr Salvelinus alpinus (L.)

The role of environmental factors in the regulation of sub‐annual increment formation in fish otoliths appears to differ markedly between species. To examine the periodicity of primary increment formation in the otoliths of O + Arctic charr, Salvelinus alpinus (L.), and the effects of temperature, and photoperiod on their formation, fish were held under controlled environmental conditions. Primary growth increments were found in the otoliths of fish held at constant temperature (18° C) and at ambient temperature [fluctuating with a circadian and circannual rhythm (4–18° C)]. Consistent and significant disruptions in increment formation occurred however, in experimental groups subjected to rapid change from ambient photoperiod to a 6L: 6D photo‐period for 96 h. Disruptions in increment formation were also observed immediately following transportation of fish between holding facilities and following disease treatment. The number of otolith increments formed in fish held on an ambient photoperiod regime, correlated closely with time elapsed in days since checkmark formation (r= 0.989, P≤0.001) in fish sampled sequentially over a period of 10 to 105 days. Thus we demonstrate that under conditions of ambient photoperiod, primary increments are formed daily.

Otolith calcification in Atlantic salmon parr, Salmo salar L. and its relation to photoperiod and calcium metabolism

Otolith calcification in Atlantic salmon parr, Salmo salar, was investigated using a radioisotope of calcium, 45Ca. Otolith calcification was found to be entrained to light‐dark cycles in salmon parr, calcium accumulation on to otoliths declining at night and resuming at dawn. The decline in Otolith calcification at night coincided with a diel decline in plasma calcium concentration. The influence of extracellular calcium on otolith increment formation was considered by inducing hypocalcemia. Induced hypocalcemia resulted in a short‐term net loss of calcium from the otolith. The results are discussed in relation to previous studies of the role of extracellular calcium in otolith formation.

Verification of daily growth increment formation in saury otoliths by rearing larvae from hatching

Naturally spawned eggs of the Pacific saury,Cololabis saira, were collected in the field and reared in a tank to examine daily periodicity of growth increment formation in the otolith. Larvae were 6.9 mm in knob length at hatching. Their otoliths (sagittae) were 31 μm in radius and had 3–6 faint concentric rings. They started feeding within two days and grew at a rate of 1.1 mm/day on average through larval and juvenile stages feeding on rotifers,Artemia nauplii, and artificial diets. Otolith growth increments showed a concentric pattern with a distance of 3.5–5.0 μm between two adjacent increments. The number of growth increments was almost equal to a known age in days plus 4 or 5. A regression line of number of increments (N) on known age in days (D) between 0–30 days after hatching was N = 4.81 + 1.01D, which shows that one increment was deposited per day.

Validation of Daily Increment Formation in the Otoliths of Juvenile Silver Perch, Bairdiella chrysoura

Otoliths of juvenile silver perch were marked by immersing live fish for 3 h in a calcein-seawater solution. Calcein produced a fluorescent mark on the sagittal otoliths that was visible under ultraviolet light. The hypothesis of one increment per day was tested by regressing the number of otolith increments that formed after marking on the number of days that fish were held in lab and field experiments. Silver perch formed one increment per day under nearly all conditions. Salinity (15‰ or 30‰) and dietary ration (4% or 10% body weight d−1) were varied among experimental groups of lab-reared fish. The short-term effect of low rations appears primarily as interrupted formation of otolith increments: fish fed 10% body weight d−1 formed one increment per day but fish fed 4% d−1 averaged less than one increment d−1. Reduction in increment formation occurred despite no significant difference in average width of otolith increments or apparent condition of silver perch over the 20-d experiment. Salinity effects were difficult to interpret: salinity interacted with ration to modify increment formation but did not independently alter the daily rate of increment formation. This novel interaction among ration and salinity is not well understood and warrants additional study. In silver perch, otolith growth appears responsive and sensitive to local environmental conditions. This responsiveness confirms the need for validation of increment formation across the range of environmental conditions that fish are likely to encounter. It also suggests that otolith structure may contain detailed information about the life history of individual silver perch.

Intrastream variation in growth rates and time of first otolith increment formation for young of the year Etheostoma simoterum (Cope) (Perciformes: Percidae)

Growth rates and otolith-estimated hatching dates of young of the year Etheostoma simoterum were studied at four localities along an elevational gradient in the Little River, Tennessee, U.S.A. during the summer of 1983. Changes in otolith increment width and mean daily air temperature corresponded well with each other, suggesting that increments were laid down daily. Growth rate increased nearly threefold from the highest elevation site to the lowest. Median otolith-estimated hatching dates differed by about 2 weeks between sites, and the pattern was not directly related to elevation. These data indicate that within-stream, life-history variation of a broadly distributed species should be taken into consideration when studying factors regulating stream fish populations along elevational gradients.

The effects of feeding periodicity and ration on the rate of increment formation in otoliths of larval walleye pollock Theragra chalcogramma (Pallas)

The effect of feeding conditions (periodicity and ration level provided) on otolith increment counts of laboratory reared larval walleye pollock Theragra chalcogramma (Pallas) was tested. Increments were deposited with daily periodicity for larvae growing under optimal feeding conditions (high, continuous ration). Increment counts determined by light microscopy were less than expected, assuming a rate of formation of 1 · day −1 for larvae grown at low rations. Increment deposition and length (and therefore growth rates) were positively correlated. Daily increment resolution was disrupted after 4 days of starvation. Evidence is discussed indicating that increments continue to be deposited on otoliths of slow-growing and starved larvae, but are too narrowly spaced for resolution by light microscopy. Feeding larvae more than once daily had no effect on increment deposition rates. For up to 38 days, increment counts from the sagitta and lapillus were equivalent, but for the first 20 days increment counts were easier from the lapillus, which was larger. After 20 days, the sagitta was larger and overall easier to read.

Effects of photoperiods on the formation of otolith increments in the embryonic and larval rainbow trout Salmo gairdneri.

Effects of 5 different pkotoregimes on otolith increment formation were observed in embryonic and larval rainbow trout. Fertilized eggs were incubated within 4h under photoperiods of 6-h light and 6-h dark (LD 6:6), LD 12:12, and LD 24:24 at about 10.3°C Other eggs at l week post-fertilization were incubated under constant light (LL) or constant darkness (DD). They were sampled at hatching and swim-up, and the number of otolith (sagitta) increments were counted under transmitted light. Sagittae first appeared as multiprimordia 1 or 2 days before the initia-tion of eye pigmentation and the initial increment was laid down at the eyed stage. The mean counts of otolith increments were highly correlated with each event of the light-dark cycles and expressed by the regression lines: Y=1.96X+29.25 for LD 6:6, Y=1.04X+14.39 for LD 12:12, and Y=0.53X+6.83 for LD 24:24 groups, where Y signifies the count of increments and X re-presents the number of days elapsed (X=O at hatching). Increments were also found under LL and DD, but the counts were variable for each individual. The mean rate of increment deposi-fion from hatching to swim-up was about 1.2 and 1.4 per day in the LL and DD groups, respec-tively. These results indicate that photoperiod works as a potent entrainer for the rhythmic formation of otolith increments in embryonic and larval rainbow trout. Some stimuli other than photoperiod may also be capable of inducing otolith increment formation.