An evaluation of stable nitrogen isotopes and polychlorinated biphenyls as bioenergetic tracers in aquatic systems

2006 ◽  
Vol 63 (3) ◽  
pp. 628-641 ◽  
Author(s):  
Gordon Paterson ◽  
Kenneth G Drouillard ◽  
G Douglas Haffner

This study investigated the relationship between stable nitrogen isotopes (δ15N) and polychlorinated biphenyl (PCB) concentrations in rock bass (Ambloplites rupestris) and bluegill sunfish (Lepomis macrochirus) with respect to age, size, and diet. δ15N signatures in both species exhibited enrichment with increasing size and approached steady state with respect to dietary δ15N values by the second year of growth. Young-of-the-year fish, however, exhibited lower nitrogen isotope enrichment over the diet, indicating that the commonly held trophic enrichment factor of 3.4‰ is more suitable for older, slow-growing individuals. PCB accumulation in both species progressed from being dominated by uptake from water in small (<100 g) fish to dietary uptake in larger individuals as a function of bioenergetic constraints such as food energy conversion and contaminant assimilation efficiencies. Significant increases in PCB accumulation were attributed to decreased specific growth rates such that ≤60% of body mass was gained on an annual basis. This effect was most noted in bluegills where higher PCB biomagnification factors were a consequence of increased foraging costs associated with an invertebrate diet. It is concluded that growth-related changes in species bioenergetics regulate both contaminant accumulation and δ15N dynamics.

2012 ◽  
Vol 279 (1746) ◽  
pp. 4441-4446 ◽  
Author(s):  
Julien Louys ◽  
Peter Ditchfield ◽  
Carlo Meloro ◽  
Sarah Elton ◽  
Laura C. Bishop

We examine the relationship between mesowear variables and carbon and nitrogen isotopes in 16 species of African antelope (Mammalia: Bovidae). We show significant differences in carbon and nitrogen isotope values between individuals exhibiting sharp versus round cusps, and high versus low occlusal relief. We show significant correlations between mesowear variables and both carbon and nitrogen isotopes. We find significant correlations between mesowear score and nitrogen, but not carbon isotopes. Finally, we find no significant correlations between hypsodonty index and either isotope examined. Our results provide strong support for the use of mesowear variables in palaeodietary reconstructions of antelopes. Our results further suggest that for the antelopes examined here, mesowear signals are a direct result of diet, while hyposodonty may be the result of phylogenetic legacy.


2005 ◽  
Vol 83 (8) ◽  
pp. 1128-1133 ◽  
Author(s):  
S J McCauley

The relationship between habitat distribution, growth rate, and plasticity was examined in the larvae of three species of dragonfly in the genus Libellula L., 1758. Growth rates were compared under three conditions: in the absence of predation risk, in the presence of sunfish (Lepomis macrochirus Rafinesque, 1819; Pisciformes: Centrachidae), and in the presence of invertebrate predators. I assessed how the habitat distributions of the three species of dragonfly, specifically how commonly they occur with fish, were related to growth rates and to the level of growth plasticity under different levels of perceived predation risk. There was a negative relationship between growth rate and the frequency with which species coexist with sunfish. Growth-rate plasticity was limited and does not appear to be important in determining the ability of species to coexist with alternative top predator types. Only one species exhibited growth-rate plasticity, decreasing growth in response to the predator with which it most commonly coexists but not to the species which poses the greatest predation risk. A comparison of growth rates and activity levels in the presence and absence of these predators suggests that growth and activity level parallel each other in these species.


1968 ◽  
Vol 25 (2) ◽  
pp. 285-297 ◽  
Author(s):  
Allen Keast

In Lake Opinicon, Ontario, the diet of the black crappie, Pomoxis nigromaculatus, undergoes a progressive change from one in which planktonic Crustacea and small-bodied Diptera larvae predominate (in fish of body length from about 60 to 115 mm), to a diet of insect larvae and fish (in fish 160–240 mm). Most food items prove to be midwater forms and the Diptera larvae are almost entirely Chaoborus and Procladius, which are free-swimming in the water column at night.An unusual feature is the prolonged nature of the Cladocera-Copepoda eating phase, which continues into year III and to a body length of about 160 mm. Gill-raker counts show P. nigromaculatus to have a specialized screen with 25–29 rakers on the first arch. In this it differs from cohabiting centrarchids in Lake Opinicon, Ambloplites rupestris, Micropterus salmoides, and Lepomis macrochirus, in which the rakers on the first arch number only 8–12. In these species plankton feeding is restricted to the earlier stages.


1988 ◽  
Vol 66 (4) ◽  
pp. 944-949 ◽  
Author(s):  
Paul F. Nicoletto ◽  
Albert C. Hendricks

A 3-year study of fish from the South River, and the South Fork of the Shenandoah River, and the Shenandoah River in Virginia revealed significant differences in the muscle mercury content of males and females. Female rock bass, Ambloplites rupestris, redbreast sunfish, Lepomis auritus, pumpkinseed, Lepomis gibbosus, and bluegill, Lepomis macrochirus contained higher levels of mercury than the males of each species. An analysis of these species indicated that sex-related differences in mercury levels were not due to differences in body size but may have been related to the onset of reproduction. For example, mercury levels in 1-year-old male and female redbreast sunfish were not significantly different: females averaged 0.66 μg Hg/g and males averaged 0.63 μg Hg/g. However, at 2 years of age, when redbreast sunfish first reproduce, females contained significantly more mercury than males: females averaged 0.84 μg Hg/g and males averaged 0.60 μg Hg/g. Analysis of the other species yielded similar results.


1988 ◽  
Vol 45 (1) ◽  
pp. 17-26 ◽  
Author(s):  
Craig W. Osenberg ◽  
Earl E. Werner ◽  
Gary G. Mittelbach ◽  
Donald J. Hall

Size-specific growth rates were determined for bluegill (Lepomis macrochirus) and pumpkinseed (L. gibbosus) sunfish collected between 1978 and 1985 in nine lakes in southwestern Michigan. Variation in growth rates was attributable to lake effects as well as an interaction between lake and year effects. Year effects explained none of the observed variation, suggesting that growth rates were influenced more by unique lake differences than by annual climatic differences. Analyses of the covariation in growth among different size-classes of bluegill and pumpkinseed revealed that small bluegill (< 55 mm standard length (SL)) and small pumpkinseed (< 40 mm SL) exhibited similar responses to environmental factors, while large bluegill (> 55 mm SL) and large pumpkinseed (> 50 mm SL) responded differently. These breaks in the growth patterns coincide with the sizes at which each species exhibits an ontogenetic shift in diet. Comparison of growth rates and resource densities suggests that the growth rates of the large fishes were food limited. Small fishes showed significant density-dependent growth. This correlative evidence for competition is in agreement with recent experimental work. We suggest that the competition between juvenile sunfishes is driven by the effects of adult resources on adult performance and the eventual recruitment of juveniles into the littoral habitat.


2009 ◽  
Vol 66 (12) ◽  
pp. 2189-2198 ◽  
Author(s):  
Michael D. Burtnyk ◽  
Gordon Paterson ◽  
Kenneth G. Drouillard ◽  
G. Douglas Haffner

This study investigated polychlorinated biphenyl (PCB) bioaccumulation patterns across age classes of bluegill ( Lepomis macrochirus ) and cisco ( Coregonus artedi ) collected from Sharbot Lake, Ontario. For bluegill, lipid normalized concentrations of PCB congeners of log Kow < 6.8 did not demonstrate any significant increases across individuals 2–5 years of age. In similarly aged cisco, however, significant age-related increases in lipid normalized PCB concentrations were observed for the majority of these congeners. For PCBs of log Kow > 6.8, these congeners demonstrated significant and similar age-related fugacity increases in both species. These patterns indicated that the bioaccumulation of less hydrophobic PCB congeners in bluegill suggest quicker growth kinetics and demonstrate the potential of this species to achieve steady state within their lifetime. In contrast, PCB bioaccumulation patterns in cisco demonstrated that biomagnification and non-steady state kinetics better reflect the capacity of this species to bioaccumulate PCBs. These results demonstrated that for pollutants of log Kow < 6.8, growth dilution and age-specific metabolic rates are critical for understanding their bioaccumulation by freshwater fish. However, for increasingly hydrophobic pollutants, their bioaccumulation reflects the biology and ecology of these species in their respective warm- and cold-water habitats.


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