Effect of stream microhabitat characteristics on rate of net energy gain by juvenile smallmouth bass, Micropterus dolomieu

1996 ◽  
Vol 46 (4) ◽  
pp. 393-403 ◽  
Author(s):  
Matthew J. Sabo ◽  
Donald J. Orth ◽  
Edmund J. Pert
Keyword(s):  
Smallmouth Bass ◽  
Energy Gain ◽  
Net Energy ◽  
Micropterus Dolomieu ◽  
Net Energy Gain

scholarly journals Incompletely Informed Shorebirds That Face a Digestive Constraint Maximize Net Energy Gain When Exploiting Patches

2003 ◽  
Vol 161 (5) ◽  
pp. 777-793 ◽  
Author(s):  
Jan A. van Gils ◽  
Ingrid W. Schenk ◽  
Oscar Bos ◽  
Theunis Piersma
Keyword(s):  
Energy Gain ◽  
Net Energy ◽  
Net Energy Gain ◽  
Digestive Constraint

Environmental cues of estrus in the North American red squirrel (Tamiasciurus hudsonicus Bangs)

1993 ◽  
Vol 71 (7) ◽  
pp. 1326-1333 ◽  
Author(s):  
C. Dustin Becker
Keyword(s):  
Annual Cycle ◽  
Energy Gain ◽  
Day Length ◽  
Tamiasciurus Hudsonicus ◽  
Positive Energy ◽  
Net Energy ◽  
Circannual Rhythm ◽  
Red Squirrels ◽  
Short Day ◽  
Net Energy Gain

During three breeding seasons, variation in the timing of estrus was monitored in wild red squirrels (Tamiasciurus hudsonicus) in a jack pine forest in central Alberta. The proximate environmental factors that affect the timing of the onset of the breeding season in female squirrels, and variation in dates of estrus, were studied in parallel laboratory and field manipulations. Wild squirrels given ad libitum sunflower seed experienced a positive energy balance (weight gains) earlier in the season than did females on a normal diet. Seed addition advanced dates of estrus by an average of 3 weeks. Three potential cuing mechanisms for the seasonal onset of estrus were proposed and tested: onset of estrus is cued by (i) a simple response to net energy gain, (ii) an interaction between an endogenous circannual rhythm and net energy gain, or (iii) an interaction between annual changes in photoperiod and net energy gain in the absence of a circannual rhythm. Our results refute the first and third mechanisms, and support the idea that red squirrels have a circannual reproductive cycle entrained by photoperiod. Net energy gain interacts with this annual cycle to fine tune the time of ovulation. In laboratory experiments, female squirrels exposed to increasing day length experienced estrus within the normal season. Squirrels kept in constant short-day conditions (< 12 h), had delayed estrus cycles. Short-day conditions did not prevent the annual cycle of reproduction, indicating that an endogenous rhythm exists and is entrained by increasing day length. Comparisons with hibernating squirrels are discussed.

Microalgae biofuels: can we achieve net energy gain and water savings?

Biofuels ◽  
2012 ◽  
Vol 3 (1) ◽  
pp. 5-8 ◽  
Author(s):  
Raymond KW Tham ◽  
Wei Zhang
Keyword(s):  
Energy Gain ◽  
Net Energy ◽  
Water Savings ◽  
Net Energy Gain

Modeling and simulation of net energy gain by dark fermentation

2012 ◽  
Vol 37 (3) ◽  
pp. 2267-2272 ◽  
Author(s):  
Karnayakage Rasika J. Perera ◽  
Yalini Arudchelvam ◽  
Venkataramana Gadhamshetty ◽  
Nagamany Nirmalakhandan
Keyword(s):  
Modeling And Simulation ◽  
Dark Fermentation ◽  
Energy Gain ◽  
Net Energy ◽  
Net Energy Gain

scholarly journals Behavioural and energetic consequences of competition among three overwintering swan (Cygnus spp.) species

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kevin A. Wood ◽  
Julia L. Newth ◽  
Geoff M. Hilton ◽  
Eileen C. Rees
Keyword(s):  
European Population ◽  
Energy Gain ◽  
Net Energy ◽  
Opposite Pattern ◽  
Time Activity ◽  
Stopover Sites ◽  
Cygnus Olor ◽  
Feeding Habitat ◽  
Bewick’S Swan ◽  
Net Energy Gain

Abstract Background Winter numbers of the northwest European population of Bewick’s Swans (Cygnus columbianus bewickii) declined recently by c. 40%. During the same period, numbers of two sympatric and ecologically-similar congeners, the Mute Swan (Cygnus olor) and Whooper Swan (Cygnus cygnus) showed increases or stability. It has been suggested that these opposing population trends could have a causal relationship, as Mute and Whooper Swans are larger and competitively dominant to Bewick’s Swans in foraging situations. If so, effects of competition of Mute and Whooper Swans on Bewick’s Swans should be detectable as measurable impacts on behaviour and energetics. Methods Here, we studied the diurnal behaviour and energetics of 1083 focal adults and first-winter juveniles (“cygnets”) of the three swan species on their winter grounds in eastern England. We analysed video recordings to derive time-activity budgets and these, together with estimates of energy gain and expenditure, were analysed to determine whether individual Bewick’s Swans altered the time spent on key behaviours when sharing feeding habitat with other swan species, and any consequences for their energy expenditure and net energy gain. Results All three swan species spent a small proportion of their total time (0.011) on aggressive interactions, and these were predominantly intraspecific (≥ 0.714). Mixed-effects models indicated that sharing feeding habitat with higher densities of Mute and Whooper Swans increased the likelihood of engaging in aggression for cygnet Bewick’s Swans, but not for adults. Higher levels of interspecific competition decreased the time spent by Bewick’s Swan cygnets on foraging, whilst adults showed the opposite pattern. When among low densities of conspecifics (< c. 200 individuals/km2), individual Bewick’s Swans spent more time on vigilance in the presence of higher densities of Mute and Whooper Swans, whilst individuals within higher density Bewick’s Swan flocks showed the opposite pattern. Crucially, we found no evidence that greater numbers of interspecific competitors affected the net energy gain of either adult or cygnet Bewick’s Swans. Conclusions We found no evidence that Bewick’s Swan net energy gain was affected by sharing agricultural feeding habitat with larger congeners during winter. This was despite some impacts on the aggression, foraging and vigilance behaviours of Bewick’s Swans, especially among cygnets. It is unlikely therefore that competition between Bewick’s Swans and either Mute or Whooper Swans at arable sites in winter has contributed to the observed decline in Bewick’s Swan numbers. Further research is needed, however, to test for competition in other parts of the flyway, including migratory stopover sites and breeding areas.

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