Growth of antarctic fish: Notothenia nudifrons and Trematomus newnesi
Field work was performed at Palmer Station from mid-February to late April 1987. I am deeply indebted to Bonnie W. Neighbors (University of Colorado, Boulder), Thomas J. Fitzgerald (Vanderbilt University), Melvyn Little (German Cancer Research Center), and George S. Bloom (University of Texas Health Science Center at Dallas) for their participation in the field research program. I gratefully acknowledge the assistance provided to the project by the personnel of ITT/Antarctic Services, Inc., by the captain and crew of RIv Polar Duke, and by the scientists of Palmer Station. This research was supported by National Science Foundation grant DPI' 83-17724. References Detrich, H.W., III. 1985. Cold-stable microtubules from antarctic fish. Antarctic Journal of the U.S., 20(5), 155-157. Detrich, H.W., III. 1986. Structure of cold-stable microtubule proteins from antarctic fishes. Antarctic Journal of the U.S., 21(5), 194-196. Detrich, H.W., III, and S.A. Overton. 1986. Heterogeneity and structure of brain tbuIins from cold-adapted antarctic fishes: Comparison
Growth of antarctic fish: Notothenia nudifrons and Trematomus newnesi RICHARD L. RADTKE
Oceanic Biology, Hawaii Institute of Geophysics University of Hawaii Honolulu, Hawaii 96822
Understanding the ecology of antarctic fishes requires information on growth variability in life history and population processes. To help provide such information on a group of fish which have no related counterparts anywhere in the world, we performed growth investigations on Notothenia nudifrons and Trematomus newnesi.
Fish growth is a continuous process of decreasing intensity inversely related to age. Internal factors (spawning, physical stress) as well as external factors (temperature, food) affect growth causing cyclic variations, which in turn affect the development of calcified tissues and are registered as growth increments. External factors tend to show regular and marked seasonal changes in temperate areas thus creating clearly identifiable annual growth periods in fishes. Studying these regular, seasonal rings in otoliths of temperate fishes is an accurate aging technique widely employed for temperate environments. Antarctic habitats are characterized by more limited and irregular changes in biotic and abiotic factors than in temperate habitats. This lack of regularity and periodicity in the seasonal changes is reflected in the fish by a rather uniform growth with smooth cycles. Growth increments laid down in the otoliths of antarctic fishes are therefore irregular and frequently related to wide spawning periods. Otoliths of long lived antarctic fishes show a series of seasonal growth marks of unknown periodicity which in some cases have been used for aging purposes (Kock 1981). In 1987
REVIEW
to brain tubulins from a temperate fish and a mammal. Journal Biological Chemistry, 261(23), 10922-10930. Detrich, H.W., III, S.A. Overton, S.F. Marchese-Ragona, and K.A. Johnson. In preparation. Assembly of tubulin from antarctic fishes. Detrich, H.W., III, V. Prasad, and R.F. Luduena. 1987. Cold-stable microtubules from antarctic fishes contain unique alpha tubulins. Journal of Biological Chemistry, 262(17), 8360-8366. Luduena, R.F., M.C. Roach, P.P. Trcka, M. Little, P. Palanivelu, P. Binkley, and V. Prasad. 1982. Beta,-Tubulin, a form of chordate brain tubulin with lesser reactivity toward an assembly-inhibiting sulfhydryl-directed cross-linking reagent. Biochemistry, 21(19), 4787-4794. Vallee, R.B. 1982. A taxol-dependent procedure for the isolation of microtubules and microtubule-associated proteins (MAPS). Journal of Cell Biology, 92, 435-442. Williams, R.C., Jr., J . J. Correia, and A.L. DeVries. 1985. Formation of microtubules at low temperature by tubulin from antarctic fish. Biochemistry, 24(11), 2790-2798. Williams, R.C., Jr., and H.W. Detrich, III. 1986. Presumptive MAPS and "cold-stable" microtubules from antarctic marine poikilotherms. Annals of the New York Academy of Sciences, 466, 436-439.
shorter living fishes (5-8 years of age) which in many cases are not important fisheries sources, the otoliths usually lack the presence of any seasonal increments that can be used for age determination. Information about events that occurred in the life of a fish can be obtained from the use of daily increments in otoliths. Otoliths are calcified tissues which may contain a large amount of biological and ecological information about a fish's life history. This information may be divulged when structural components of otoliths are investigated. During favorable periods of fast growth, an area rich in protein is laid down in the otoliths. During unfavorable periods or slow growth, an area higher in calcium content is laid down in the otoliths. This process results in daily increments. Daily increments have been found in otoliths from a host of fish species (see reviews by Campana and Neilson 1985; Jones 1986). Daily increments are laid down in relation to metabolic daily cycles which are in turn synchronized with photoperiodicity. Otoliths in this study were prepared as described in Radtke and Targett (1984). Internal examination of otoliths from the antarctic fish, Notothenia nudifrons and Trematomus ncwnesi, by scanning electron microscope methodology revealed internal rhythmic patterns. Results from the marking experiments with both tetracycline (Notothenia nudifrons and Trefnatomus newnesz) and acetazolomide (Notothenia nudifrons.) demonstrated that linear markings were formed at the rate of one per day. Tetracycline is an antibiotic which is incorporated into the otolith and marks the time of injection. When viewed under a compound microscope at filtered reflected wavelengths of 700-800 nanometers tetracycline fluoresces and appears as a fluorescent band inside the otolith. The microincrements can then be counted beyond that point. Acetazolamide is a diuretic which causes a cessation of calcium deposition and leaves a distinct mark on the otoliths. This can be used as a benchmark, making it possible to count the increments beyond the mark. The validation of the increments enabled us to validate the microincrements seen by scanning electron microscope which revealed small increments, some less than 0.2 microns in width. 219
These increments were visible with scanning electron microscope preparations. These data conformed well to a linear equation (N. nudifrons) and to the von Bertalanffy equation (T. newnesi) (von Bertalanffy 1957) and provided a reliable growth estimate of the populations of N. nudifrons (figure 1) and T newnesi on the Antarctic Peninsula (figure 2). The growth patterns determined in the present study based on a size range of fish made it feasible to determine the precise nature of the entire growth curve. N. nudifrons grew slowly, reaching sexual maturity at an age of 4-5 years, with the largest fish attaining ages of more than 8 years. Growth and survivorship were similar for males and females. Increments of both larvae and adults were deposited on a daily basis, even during the winter months, as validated through marking experiments. These techniques allowed the determination of the age, growth, and natural morality of N. nudifrons and T newnesi. N. nudifrons grew slowly, reaching sexual maturity at an age of 4-5 years, with the largest fish attaining ages of more than 8 years. Growth and survivorship were similar for males and females. T. newnesi also grew slowly, reaching an age of 7 years. Growth and survivorship were similar to other antarctic fish. The otoliths of N. nudifrons and T. newnesi contain microincrements which are easily counted using scanning electron microscope techniques. Two lines of evidence support the assumption that the observed growth increments reflect daily growth: first, similar microincrements have been verified to be daily in many of the temperate and tropical fishes previously investigated, and second, the number of increments in the validation experiments suggests that one increment is formed per day. The validation experiments in this study strongly support that increments in antarctic fish otoliths form on a daily basis. Analyses of otoliths of antarctic fish have shown the promise of this technique in the determination of age and growth (Radtke and Targett 1984). For antarctic fish, daily increments in otoliths furnish the best avenue for age resolution. The present study was intended to demonstrate the potential of scanning electron microscope techniques. Daily increment analyses cannot answer all the questions of antarctic fish biology, but they do make it feasible to reconstruct a record of a fish's past and to understand the age and subsequent population dynamics of antarctic fish.
180 160 140 120 C) 100 C . 80 60 V C co 40 C/) 20 0
0 500 1000 1500 2000 2500
Age(days)
Figure 2. Relationship of fish standard length (SL) to age as determined from the number of sagittal otolith microincrements. Von Bertalanify (1957) growth curve for T newnesi is based on daily increment counts from sagittae of 15 specimens read with a scanfling electron microscope. L. (length at infinity) = 194.77 millimeters standard length, K (growth coefficient) = 0.001 per day, t0 (time zero) = -14.99 days, r2 (correlation coefficient = 0.99.
Daily increments are also helpful in determining the significance of growth checks in otoliths of long-lived species. Because spawning periods are reflected in the otolith structures of most species, the presence of such marks may allow for the determination of the spawning frequency and duration. Due to the function of the otoliths as part of the inner ear, their constituent materials which are laid down in equilibrium with the environment are not removed or absorbed. Thus, the otoliths can act as a register of the environmental conditions experienced by the fish during their lifespan. Moreover, the width of the increments may be closely correlated with the fish growth allowing otolith structural data to act as information storage units of biological periods and growth fluctuation in the fish. The use of daily increments greatly increases the value of otoliths as recorders of a fish's life history. Thanks are due to T. Hourigan, J. Bell, T. Targett, and the staff of Palmer Station for help in collecting and rearing. T. Hourigan, S. Folsom, C. Rowland, and K. Hill helped with sample collection, preparation, and data analyses. This research was supported by National Science Foundation grant DPI' 85-21017.
160
References
140
E • 120 C) CD
100
43 80 C
C/) 60 40 . 0 500 1000 1500 2000 2500 3000 3500
Age (days)
Figure 1. Relationship of fish standard length (SL) and age as determined from the number of sagittal otolith microincrements for N. nudifrons.
220
Kock, K.H. 1981. Biological fishing investigations of three species of antarctic fish: Chapsocephalus gunnari (Lonnberg, 1905), Chaenocephalus aceratus (Lonnberg, 1906) and Pseudochaenichthys georgianus (Norman, 1937) (Nototheniidae, Channichtyldae). Mit Inst it ut Seefischerei, 32, 1-226. (In German) Campana, S.E., and J.D. Neilson. 1985. Microstructure of fish otoliths. Canadian Journal Fisheries Aquatic Science, 42, 1014-1032. Jones, C. 1986. Determining age of larval fish with the otolith increment technique. Fishery Bulletin U.S., 84, 91-103. Radtke, R.L., and T.E. Targett. 1984. Structural and chemical rhythmic patterns in the otoliths of the Antarctic fish Notothenia larseni and their application to age determination. Polar Biology, 3, 203-210. von Bertalanffy, L. 1957. Quantitative laws on metabolism and growth. Quarterly Review of Biology, 32, 217-231.
ANTARCFIC JOURNAL
Growth of antarctic fish: Notothenia nudifrons and Trematomus newnesi RICHARD L. RADTKE
Oceanic Biology, Hawaii Institute of Geophysics University of Hawaii Honolulu, Hawaii 96822
Understanding the ecology of antarctic fishes requires information on growth variability in life history and population processes. To help provide such information on a group of fish which have no related counterparts anywhere in the world, we performed growth investigations on Notothenia nudifrons and Trematomus newnesi.
Fish growth is a continuous process of decreasing intensity inversely related to age. Internal factors (spawning, physical stress) as well as external factors (temperature, food) affect growth causing cyclic variations, which in turn affect the development of calcified tissues and are registered as growth increments. External factors tend to show regular and marked seasonal changes in temperate areas thus creating clearly identifiable annual growth periods in fishes. Studying these regular, seasonal rings in otoliths of temperate fishes is an accurate aging technique widely employed for temperate environments. Antarctic habitats are characterized by more limited and irregular changes in biotic and abiotic factors than in temperate habitats. This lack of regularity and periodicity in the seasonal changes is reflected in the fish by a rather uniform growth with smooth cycles. Growth increments laid down in the otoliths of antarctic fishes are therefore irregular and frequently related to wide spawning periods. Otoliths of long lived antarctic fishes show a series of seasonal growth marks of unknown periodicity which in some cases have been used for aging purposes (Kock 1981). In 1987
REVIEW
to brain tubulins from a temperate fish and a mammal. Journal Biological Chemistry, 261(23), 10922-10930. Detrich, H.W., III, S.A. Overton, S.F. Marchese-Ragona, and K.A. Johnson. In preparation. Assembly of tubulin from antarctic fishes. Detrich, H.W., III, V. Prasad, and R.F. Luduena. 1987. Cold-stable microtubules from antarctic fishes contain unique alpha tubulins. Journal of Biological Chemistry, 262(17), 8360-8366. Luduena, R.F., M.C. Roach, P.P. Trcka, M. Little, P. Palanivelu, P. Binkley, and V. Prasad. 1982. Beta,-Tubulin, a form of chordate brain tubulin with lesser reactivity toward an assembly-inhibiting sulfhydryl-directed cross-linking reagent. Biochemistry, 21(19), 4787-4794. Vallee, R.B. 1982. A taxol-dependent procedure for the isolation of microtubules and microtubule-associated proteins (MAPS). Journal of Cell Biology, 92, 435-442. Williams, R.C., Jr., J . J. Correia, and A.L. DeVries. 1985. Formation of microtubules at low temperature by tubulin from antarctic fish. Biochemistry, 24(11), 2790-2798. Williams, R.C., Jr., and H.W. Detrich, III. 1986. Presumptive MAPS and "cold-stable" microtubules from antarctic marine poikilotherms. Annals of the New York Academy of Sciences, 466, 436-439.
shorter living fishes (5-8 years of age) which in many cases are not important fisheries sources, the otoliths usually lack the presence of any seasonal increments that can be used for age determination. Information about events that occurred in the life of a fish can be obtained from the use of daily increments in otoliths. Otoliths are calcified tissues which may contain a large amount of biological and ecological information about a fish's life history. This information may be divulged when structural components of otoliths are investigated. During favorable periods of fast growth, an area rich in protein is laid down in the otoliths. During unfavorable periods or slow growth, an area higher in calcium content is laid down in the otoliths. This process results in daily increments. Daily increments have been found in otoliths from a host of fish species (see reviews by Campana and Neilson 1985; Jones 1986). Daily increments are laid down in relation to metabolic daily cycles which are in turn synchronized with photoperiodicity. Otoliths in this study were prepared as described in Radtke and Targett (1984). Internal examination of otoliths from the antarctic fish, Notothenia nudifrons and Trematomus ncwnesi, by scanning electron microscope methodology revealed internal rhythmic patterns. Results from the marking experiments with both tetracycline (Notothenia nudifrons and Trefnatomus newnesz) and acetazolomide (Notothenia nudifrons.) demonstrated that linear markings were formed at the rate of one per day. Tetracycline is an antibiotic which is incorporated into the otolith and marks the time of injection. When viewed under a compound microscope at filtered reflected wavelengths of 700-800 nanometers tetracycline fluoresces and appears as a fluorescent band inside the otolith. The microincrements can then be counted beyond that point. Acetazolamide is a diuretic which causes a cessation of calcium deposition and leaves a distinct mark on the otoliths. This can be used as a benchmark, making it possible to count the increments beyond the mark. The validation of the increments enabled us to validate the microincrements seen by scanning electron microscope which revealed small increments, some less than 0.2 microns in width. 219
These increments were visible with scanning electron microscope preparations. These data conformed well to a linear equation (N. nudifrons) and to the von Bertalanffy equation (T. newnesi) (von Bertalanffy 1957) and provided a reliable growth estimate of the populations of N. nudifrons (figure 1) and T newnesi on the Antarctic Peninsula (figure 2). The growth patterns determined in the present study based on a size range of fish made it feasible to determine the precise nature of the entire growth curve. N. nudifrons grew slowly, reaching sexual maturity at an age of 4-5 years, with the largest fish attaining ages of more than 8 years. Growth and survivorship were similar for males and females. Increments of both larvae and adults were deposited on a daily basis, even during the winter months, as validated through marking experiments. These techniques allowed the determination of the age, growth, and natural morality of N. nudifrons and T newnesi. N. nudifrons grew slowly, reaching sexual maturity at an age of 4-5 years, with the largest fish attaining ages of more than 8 years. Growth and survivorship were similar for males and females. T. newnesi also grew slowly, reaching an age of 7 years. Growth and survivorship were similar to other antarctic fish. The otoliths of N. nudifrons and T. newnesi contain microincrements which are easily counted using scanning electron microscope techniques. Two lines of evidence support the assumption that the observed growth increments reflect daily growth: first, similar microincrements have been verified to be daily in many of the temperate and tropical fishes previously investigated, and second, the number of increments in the validation experiments suggests that one increment is formed per day. The validation experiments in this study strongly support that increments in antarctic fish otoliths form on a daily basis. Analyses of otoliths of antarctic fish have shown the promise of this technique in the determination of age and growth (Radtke and Targett 1984). For antarctic fish, daily increments in otoliths furnish the best avenue for age resolution. The present study was intended to demonstrate the potential of scanning electron microscope techniques. Daily increment analyses cannot answer all the questions of antarctic fish biology, but they do make it feasible to reconstruct a record of a fish's past and to understand the age and subsequent population dynamics of antarctic fish.
180 160 140 120 C) 100 C . 80 60 V C co 40 C/) 20 0
0 500 1000 1500 2000 2500
Age(days)
Figure 2. Relationship of fish standard length (SL) to age as determined from the number of sagittal otolith microincrements. Von Bertalanify (1957) growth curve for T newnesi is based on daily increment counts from sagittae of 15 specimens read with a scanfling electron microscope. L. (length at infinity) = 194.77 millimeters standard length, K (growth coefficient) = 0.001 per day, t0 (time zero) = -14.99 days, r2 (correlation coefficient = 0.99.
Daily increments are also helpful in determining the significance of growth checks in otoliths of long-lived species. Because spawning periods are reflected in the otolith structures of most species, the presence of such marks may allow for the determination of the spawning frequency and duration. Due to the function of the otoliths as part of the inner ear, their constituent materials which are laid down in equilibrium with the environment are not removed or absorbed. Thus, the otoliths can act as a register of the environmental conditions experienced by the fish during their lifespan. Moreover, the width of the increments may be closely correlated with the fish growth allowing otolith structural data to act as information storage units of biological periods and growth fluctuation in the fish. The use of daily increments greatly increases the value of otoliths as recorders of a fish's life history. Thanks are due to T. Hourigan, J. Bell, T. Targett, and the staff of Palmer Station for help in collecting and rearing. T. Hourigan, S. Folsom, C. Rowland, and K. Hill helped with sample collection, preparation, and data analyses. This research was supported by National Science Foundation grant DPI' 85-21017.
160
References
140
E • 120 C) CD
100
43 80 C
C/) 60 40 . 0 500 1000 1500 2000 2500 3000 3500
Age (days)
Figure 1. Relationship of fish standard length (SL) and age as determined from the number of sagittal otolith microincrements for N. nudifrons.
220
Kock, K.H. 1981. Biological fishing investigations of three species of antarctic fish: Chapsocephalus gunnari (Lonnberg, 1905), Chaenocephalus aceratus (Lonnberg, 1906) and Pseudochaenichthys georgianus (Norman, 1937) (Nototheniidae, Channichtyldae). Mit Inst it ut Seefischerei, 32, 1-226. (In German) Campana, S.E., and J.D. Neilson. 1985. Microstructure of fish otoliths. Canadian Journal Fisheries Aquatic Science, 42, 1014-1032. Jones, C. 1986. Determining age of larval fish with the otolith increment technique. Fishery Bulletin U.S., 84, 91-103. Radtke, R.L., and T.E. Targett. 1984. Structural and chemical rhythmic patterns in the otoliths of the Antarctic fish Notothenia larseni and their application to age determination. Polar Biology, 3, 203-210. von Bertalanffy, L. 1957. Quantitative laws on metabolism and growth. Quarterly Review of Biology, 32, 217-231.
ANTARCFIC JOURNAL
