Energy Metabolism and Amino Acid Transport During Early Development of Antarctic and Temperate Echinoderms

Abstract

The rates of oxygen consumption by embryos of antarctic echinoderms (Acodontaster hodgsoni, Odontaster validus, Psilaster charcoti, and Sterechinus neumayeri) were compared to the biomas (ash-free dry organic weight) of the egg of each species. These species could survive for months to years (range: 10 months to 5 years) by relying solely on the reserves present in the egg. However, certain species did not use any of the egg's reserves during early development. Embryonic stages of O. validus (a species with planktotrophic larvae) did not decrease in lipid, protein, or total biomass during the first 35 days of development. During the first 42 days of development, embryos of A. hodgsoni (a species with lecithotrophic development) used protein as an energy source. For both species lipid composed 40 to 50% of egg biomass, but was not used as an energy reserve. Larvae of O. validus have a high-affinity transport system for amino acids dissolved in seawater (K1 = 1.3 {mu}M for alanine). The rate of alanine transport from a low concentration (50 nM) could supply 32% of the larva's metabolic needs. This is a 10-fold higher input to metabolism than was determined (3% at 50 nM) for larvae of a temperate asteroid, Asterina miniata. Larvae of antarctic echinoderms live in an environment where the food supply is low for most of the year. Relative to their metabolic rates, antarctic larvae have larger energy stores and planktotrophic larvae have higher nutrient transport capacities when compared to larvae from temperate regions. These physiological differences allow antarctic larvae to survive for long periods without particulate food.

DNA photorepair in echinoid embryos: effects of temperature on repair rate in Antarctic and non-Antarctic species

“…Despite these limitations however, researchers often make useful comparisons of the physiology of distantly related Antarctic and non-Antarctic species (i.e. HoeghGuldberg et al, 1991;Viarengo et al, 1994;Shilling and Manahan, 1994;Marsh et al, 2001), with the comparisons yielding significant insights into the biology of coldadapted organisms. With these limitations in mind, we compared rates of photoreactivation as a function of ambient and experimental temperature in all three species, and rates of photoreactivation as a function of developmental stage in Sterechinus.…”

Availability of dissolved organic matter offsets metabolic costs of a protracted larval period for Bugula neritina (Bryozoa)

“…The majority of studies examin ing the nutritional role of DOM have focused primarily on indirect estimations of beneWt attained by calcula tions based on metabolic activity and uptake rate (e.g., Jaeckle and Manahan 1989;Shilling and Manahan 1994;Jaeckle 1994;Ben-David-Zaslow and Benayahu 2000). Direct comparisons determining the actual beneWt of DOM transport to growth, survivability and reproduc tion of organisms are almost wholly lacking from the lit erature and have yielded contradictory results (e.g., Shick 1975;Ferguson 1980a).…”

“…Rather, potential ben eWts have been estimated by comparing metabolic expenditure and the amount of energy gained through rates of DOM uptake (e.g., Jaeckle and Manahan 1989;Shilling and Manahan 1994;Jaeckle 1994;Ben-DavidZaslow and Benayahu 2000). A more direct assessment of the energetic and ecological beneWts of DOM trans port could be achieved through performance compari sons of individuals in the presence and absence of DOM.…”

Experimental ocean acidification alters the allocation of metabolic energy

“…The difference in metabolic response between fed and unfed larvae suggests that nutritional and physiological states impact the response to many environmental stressors, including ocean acidification (47). Such increases in metabolic demand have important implications for long-term resistance to starvation of larval forms with minimal energy reserves (48,49). Metabolic responses of fed larvae.…”