title: Effects of warm acclimation on physiology and gonad development in the sea urchin Evechinus chloroticus.
abstract: The physiology of the New Zealand sea urchin Evechinus chloroticus was evaluated through feeding, respiration, growth and gonad growth in adult animals acclimated for 90days at 18°C (annual mean temperature) and 24°C (ambient summer temperature (21°C) +3°C). Measured parameters with representative rates of assimilation efficiency were used to calculate scope for growth (SfG) for each treatment. All physiological parameters were negatively affected at 24°C, showing a decrease in feeding rate which coincided with negative growth and gonad development at the end of the acclimation period, and a decrease in respiration rate suggesting metabolic depression. Histology of gonad samples after the acclimation period also showed no gametic material in animals acclimated at 24°C. All animals acclimated at 24°C had negative growth, differing from the calculated SfG which indicated that the animals had sufficient energy for production. The results suggest that calculated SfG in echinoderms should be used together with actual measurements of growth in individuals as, by itself, SfG may underestimate the actual effect of ocean warming when animals are exposed to stressful conditions. Overall, considering the total loss of reproductive output observed in E. chloroticus at higher temperatures, an increase in seawater temperature could dramatically influence the persistence of northern populations of this species, leading to flow-on effects in the subtidal ecosystem.
authors.affiliation: School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; Institute of Marine Science, Leigh Marine Laboratory, University of Auckland, P.O. Box 349, Warkworth 0941, New Zealand. Electronic address: dnat029@aucklanduni.ac.nz.
authors.forename: Natalí J
authors.initials: NJ
authors.lastname: Delorme
authors.affiliation: School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
authors.forename: Mary A
authors.initials: MA
authors.lastname: Sewell
mesh_terms: D000064:Acclimatization / Q000502:physiology; D000818:Animals; D001835:Body Weight; D004435:Eating; D005260:Female; D008297:Male; D010053:Ovary / Q000254:growth & development*; D012119:Respiration; D012617:Sea Urchins / Q000254:growth & development / Q000502:physiology*; D013696:Temperature; D013737:Testis / Q000254:growth & development*
keywords: Climate change; Ecophysiology; Feeding; Growth; Reproduction; Respiration; Scope for growth; Sea urchin