Absorption of nutrient exudates from terrapin eggs by roots of Ammophila breviligulata (Gramineae)

Ammophila breviligulata Fem. is a dominant grass in the nutrient-poor soil of sand dunes along the east coast of North America. More than half its range overlaps that of Malaclemys terrapin Schoepff., a brackish water turtle nesting in sand dunes. Roots of A. breviligulata often proliferate around buried terrapin nests. Gamma spectrometry was used to determine whether nutrients are translocated from terrapin eggs into A. breviligulata. Eggs, collected in the field within 48 h of being laid, were injected with 75 Se, 137 Cs, 54 Mn, and 59 Fe. Labelled eggs were covered with dune soil in pots containing A. breviligulata. Plants were then monitored over 15 weeks for the appearance of isotopes. Within 45 days, all isotopes except 59 Fe were found in aerial shoots, more than 30 cm from buried eggs. Iron was absorbed but remained in the roots. The other three isotopes steadily accumulated in shoots for 90 days, after which they began to be translocated to underground tissues. Thus, A. breviligulata absorbs nutrients exuding from buried terrapin eggs, utilizing this novel nutrient supply in mineral-deficient soils of barrier dunes.