27 research outputs found
Maternal Age as a Determinant of Larval Growth and Survival in a Marine Fish, \u3ci\u3eSebastes Melanops\u3c/i\u3e
Relative body size has long been recognized as a factor influencing reproductive success in fishes, but maternal age has only recently been considered. We monitored growth and starvation resistance in larvae from 20 female black rockfish (Sebastes melanops), ranging in age from five to 17 years. Larvae from the oldest females in our experiments had growth rates more than three times as fast and survived starvation more than twice as long as larvae from the youngest females. Female age was a far better predictor of larval performance than female size. The apparent underlying mechanism is a greater provisioning of larvae with energy-rich triacylglycerol (TAG) lipids as female age increases. The volume of the oil globule (composed primarily of TAG) present in larvae at parturition increases with maternal age and is correlated with subsequent growth and survival. These results suggest that progeny from older females can survive under a broader range of environmental conditions compared to progeny from younger females. Age truncation commonly induced by fisheries may, therefore, have severe consequences for long-term sustainability of fish populations
Recommended from our members
Food deprivation affects vertical distribution and activity of a marine fish in a thermal gradient: potential energy-conserving mechanisms
The effects of reduced food availability on the behavior of juvenile walleye pollock Theragra chalcogramma were examined in laboratory experiments designed to test for potential energy-conserving responses. Groups of juvenile fish were held on 1 of 6 ration treatments ranging from ad libitum to near starvation, and then vertical distribution and activity levels were quantified in a 2.5 m deep water column under isothermal and thermally stratified conditions. Stratification resulted in a general shift to the upper, warmer layer in the 2 experiments employing a sharp thermocline at mid-depth, but the occurrence of fish in the colder bottom layer varied with different ration treatments. Movement into cold water increased in intermediate ration groups compared to high ration groups. Since reduced temperatures should reduce metabolic costs, this behavior is consistent with our hypothesis that food deprivation should invoke energy-saving behaviors. However, activity levels increased for fish held on intermediate rations, suggesting that the greater movement into cold water was a corollary result of increased searching for food. Fish in the lowest ration treatments had decreased activity levels, but also decreased their movement into cold water when a sharp thermocline was present, negating potential bioenergetic benefits. In the third experiment, there was a gradual thermal gradient from surface to bottom rather than a sharp thermocline. Temperatures associated with vertical positions of the fish were determined. In this experiment, clear energy-conserving responses to temperature were displayed by food-deprived fish; the average temperatures occupied by fish on starvation rations were 3 to 4 degree C colder than those of the higher ration groups. Based on the high Q sub(10) for metabolic rates of juvenile pollock, these reduced temperatures potentially conferred energy savings of up to 34%, relative to the metabolic expenditures of fish on high rations. The contrast in behavior for the lowest ration groups between sharply stratified and gradually stratified conditions suggested that the severity of the temperature gradient influenced the fishes' ability to take advantage of cold water as an energetic refuge. The behavior of fish in the laboratory was consistent with prior observations in the Bering Sea, where juvenile walleye pollock remained in surface waters if food availability was high, but initiated vertical migration into deeper, colder water with reduced prey densities. Results of this study demonstrated a broad flexibility in the behavioral mechanisms used by walleye pollock to deal with declining food levels. The initial response to food limitation was increased activity, indicative of greater searching behavior. With extended food deprivation, a switch to energy-conserving behavior was evident. The temperature responses of fish experiencing severe food limitation provided support for a bioenergetic hypothesis of diel vertical migration.Keywords: Starvation, Bioenergetics, Walleye pollock, Temperature, BehaviorKeywords: Starvation, Bioenergetics, Walleye pollock, Temperature, Behavio
Species-Specific Responses of Juvenile Rockfish to Elevated pCO2: From Behavior to Genomics
In the California Current ecosystem, global climate change is predicted to trigger large-scale changes in ocean chemistry within this century. Ocean acidificationâwhich occurs when increased levels of atmospheric CO2 dissolve into the oceanâis one of the biggest potential threats to marine life. In a coastal upwelling system, we compared the effects of chronic exposure to low pH (elevated pCO2) at four treatment levels (i.e., pCO2 = ambient [500], moderate [750], high [1900], and extreme [2800 ÎŒatm]) on behavior, physiology, and patterns of gene expression in white muscle tissue of juvenile rockfish (genus Sebastes), integrating responses from the transcriptome to the whole organism level. Experiments were conducted simultaneously on two closely related species that both inhabit kelp forests, yet differ in early life history traits, to compare high-CO2 tolerance among species. Our findings indicate that these congeners express different sensitivities to elevated CO2 levels. Copper rockfish (S. caurinus) exhibited changes in behavioral lateralization, reduced critical swimming speed, depressed aerobic scope, changes in metabolic enzyme activity, and increases in the expression of transcription factors and regulatory genes at high pCO2 exposure. Blue rockfish (S. mystinus), in contrast, showed no significant changes in behavior, swimming physiology, or aerobic capacity, but did exhibit significant changes in the expression of muscle structural genes as a function of pCO2, indicating acclimatization potential. The capacity of long-lived, late to mature, commercially important fish to acclimatize and adapt to changing ocean chemistry over the next 50â100 years is likely dependent on species-specific physiological tolerances
Does fish larval dispersal differ between high and low latitudes?
Author Posting. © The Author(s), 2013. This is the author's version of the work. It is posted here by permission of The Royal Society for personal use, not for redistribution. The definitive version was published in Proceedings of the Royal Society B Biological Sciences 280 (2013): 20130327, doi:10.1098/rspb.2013.0327.Several factors lead to expectations that the scale of larval dispersal and population
connectivity of marine animals differs with latitude. We examine this expectation for
demersal shorefishes, including relevant mechanisms, assumptions, and evidence.
We explore latitudinal differences in: 1) biological (e.g., species composition,
spawning mode, pelagic larval duration (PLD)), 2) physical (e.g., water movement,
habitat fragmentation), and 3) biophysical factors (primarily temperature, which could
strongly affect development, swimming ability, or feeding). Latitudinal differences
exist in taxonomic composition, habitat fragmentation, temperature, and larval
swimming, and each could influence larval dispersal. Nevertheless, clear evidence
for latitudinal differences in larval dispersal at the level of broad faunas is lacking.
For example, PLD is strongly influenced by taxon, habitat, and geographic region,
but no independent latitudinal trend is present in published PLD values. Any trends
in larval dispersal may be obscured by a lack of appropriate information, or use of
âoff the shelfâ information that is biased with regard to the species assemblages in
areas of concern. Biases may also be introduced from latitudinal differences in taxa
or spawning modes, as well as limited latitudinal sampling. We suggest research to
make progress on the question of latitudinal trends in larval dispersal.TK was supported by the Norwegian Research Council through project
MENUII #190286. JML was supported by ARC Discovery Grant DP110100695.
JEC and RRW were supported by the Partnership for the Interdisciplinary Study of
Coastal Oceans, funded by The David and Lucille Packard Foundation and the
Gordon and Betty Moore Foundation.2014-03-2
Appendix A. The results of all stepwise multiple regression analyses.
The results of all stepwise multiple regression analyses
Steelhead Ration Schedule
This file shows the sequence of high and low ration treatments for each tank and the date at which changes in ration occurred
Recommended from our members
Multipleâbrooding rockfishes (Sebastes spp.) can utilize stored sperm from individual sires to fertilize consecutive broods
Viviparous rockfishes (Sebastes spp., family Scorpaenidae) mate and store sperm in the ovaries for several months prior to fertilization, as oocytes develop for the parturition season. Although multiple paternity has been documented in single-brooding rockfishes, paternity in consecutive broods of multiple-brooding species has not been studied. Analyses of multilocus microsatellite genotypes in both residual larvae left in the ovary from a previous parturition and upcoming fertilized broods in the same ovary demonstrated evidence of the same sires in consecutive broods in chilipepper (Sebastes goodei) and speckled (Sebastes ovalis) rockfishes. One S. goodei mother showed evidence of multiple paternity from the same two sires in both consecutive broods. The ability to retain sperm, even after a parturition event, for use in subsequent broods, confers an advantage to ensure fertilization and allows for extension of the parturition season. This life-history strategy provides a bet-hedging advantage in the California Current system, an environmentally dynamic ecosystem where larval survivorship and subsequent recruitment to adult populations can vary temporally by orders of magnitude
Data from: Separating intrinsic and environmental contributions to growth and their population consequences
Among-individual heterogeneity in growth is a commonly observed phenomenon that has clear consequences for population and community dynamics yet has proved difficult to quantify in practice. In particular, observed among-individual variation in growth can be difficult to link to any given mechanism. Here, we develop a Bayesian state-space framework for modeling growth that bridges the complexity of bioenergetic models and the statistical simplicity of phenomenological growth models. The model allows for intrinsic individual variation in traits, a shared environment, process stochasticity, and measurement error. We apply the model to two populations of steelhead trout (Oncorhynchus mykiss) grown under common but temporally varying food conditions. Models allowing for individual variation match available data better than models that assume a single shared trait for all individuals. Estimated individual variation translated into a roughly twofold range in realized growth rates within populations. Comparisons between populations showed strong differences in trait means, trait variability, and responses to a shared environment. Together, individual- and population-level variation have substantial implications for variation in size and growth rates among and within populations. State-dependent life-history models predict that this variation can lead to differences in individual life-history expression, lifetime reproductive output, and population life-history diversity