Cardiovascular performance of six species of field-acclimatized centrarchid sunfish during the parental care period

Abstract

SUMMARYParental care is an energetically costly period of the life history of many fish species characterized by extended high intensity activity. To date, there have been no studies that have investigated the cardiovascular correlates of extended parental care in fish. Using Doppler flow probes, the cardiovascular performance of six syntopic centrarchid fish species (N232) that provide sole, male parental care was examined across a range of water temperatures that encompass their reproductive periods (14-26°C). Experiments were restricted to males but included both nesting and non-nesting individuals to evaluate the cardiovascular performance of fish during parental care. Resting values for cardiac output (Q) and heart rate (f H ) tended to be higher for nesting fish when adjusted for variation in temperature. Both of these cardiac variables also increased with water temperature. Stroke volume (V S ) was similar among nesting and non-nesting fish and was generally thermally insensitive. When exposed to exhaustive exercise, nesting fish took longer to exhaust than non-nesting individuals. The high resting levels found in nesting fish accompanied by only minor increases in maximal values typically resulted in reductions in cardiac scope. Cardiovascular variables recovered more quickly in nesting fish, which could facilitate the high activity and bursting associated with parental care. Interspecifically, several cardiovascular variables were correlated with parental care activity. Parental care investment became more energetically expensive as the degree of cardiac frequency modulation decreased. Additionally, as the duration of parental care increased, so did the time required for fish to become exhausted, although this relationship was probably influenced by the fact that the larger species (e.g. smallmouth bass Micropterus dolomieu; largemouth bass Micropterus salmoides) provided the lengthiest care. Collectively, these data indicate that fish that provide parental care possess adaptations, including sufficient phenotypic plasticity, such that they can enhance their ability to provide high intensity protracted care, and emphasize the nexus between behavior and physiology.Supplementary material available online at

Neonatal body condition, immune responsiveness, and hematocrit predict longevity in a wild bird population

“…2). Interestingly, hematocrit often declines in breeding individuals providing energetically demanding parental care relative to non-breeding individuals across a wide range of vertebrate taxa (Williams et al 2004, Fair et al 2007, Hanson and Cooke 2009, Cooke et al 2010), although further work is needed to determine whether this is an adaptive reduction to facilitate increased energetic demands or a consequence of osmoregulatory adjustments to blood during reproduction (Williams et al 2004, Fair et al 2007, Wagner et al 2008, Williams 2012). Thus, hematocrit may play an important role in the life history of all vertebrates, and further experimental work may shed light on the functional significance of this trait in mediating long-term consequences for survival and reproduction.…”

Habitat selection by foraging macaroni penguins correlates with hematocrit, an index of aerobic condition

“…Hematocrit varies markedly in birds, with some of the highest values observed in migratory birds (Piersma et al 1996), but declining after breeding to lows during the postnuptial molt (Hõrak et al 1998, Davey et al 2000, Williams 2012). Declines during the breeding season have been documented in a number of birds (and in many other taxa as well), the ecological relevance of which has been previously underappreciated (Williams et al 2004, Fair et al 2007, Hanson & Cooke 2009, Cooke et al 2010, Williams 2012, Bowers et al 2014. As nearly all life-history functions are intimately linked to oxygen-carrying capacity, low capacity or low hematocrit can have deleterious effects on fitness in wild animals.…”

Exploring the Relationship Between Physiological Performance and Reproductive Investment in Wild Fish Using Heart Rate Biologgers

“…A marginally non-significant positive relationship between R%fH and parental male aggression level was detected (Figure 2.6), however this did not affect parental care behaviours, specifically nest defending, nest tending and nest guarding investment. Hence, our results partially support the hypothesis: although fH is related to an individual's aggression level, the lack of relationship between fH and parental care behaviours suggests that fH alone does not appear to be directly related to parental care investment in smallmouth bass.The recorded fH conforms with the rates reported in previous literature(Schreer et al 2001 (16°C = 34.5 beats min -1 ±2.7 beats min -1 and 20°C = 52.8 beats min -1 ± 2.5 beats min -1 for routine fH and scope for fH ranging between 1.8 and 2.6 fold); Cooke 2004 (21°C = ~49 beats min -1 for routine);Cooke et al 2010 (21°C= ~50 beats min -1 for routine);Cooke et al 2004b (in largemouth bass (Micropterus salmoides) 17°C = ~48 beats min -1 , 21°C = ~50 beats min -1 , and 25°C = ~ 60 beats min -1 for routine fH; 17°C = ~80 beats min -1 , 21°C = ~90 beats min -1 , and 25°C = ~ 120 beats min -1 for max fH), measured within the same temperature range (16-23°C).…”

“…The apparent relationships between cardiovascular performance and metabolism, and physiological capacity for exercise and parental care behaviour has motivated the hypothesis that fitness and fitness-related behaviours are strongly influenced by cardiovascular performance (Franklin and Davie 1992;Cooke 2004;Farrell et al 2008;Cooke et al 2010). Previous research has shown that smallmouth bass (and other centrarchid species) undergo behavioural and physiological adaptations, including modulating fH to enhance reproductive performance .…”