Zostera marina

Taxonomy: Eukaryota; Viridiplantae; Streptophyta; Streptophytina; Embryophyta; Tracheophyta; Euphyllophyta; Spermatophyta; Magnoliophyta; Liliopsida; Alismatales; Zosteraceae; Zostera

Introduction

Zostera is a small genus of widely distributed seagrass, commonly called marine eelgrass or simply eelgrass. The genus contains twelve species. Eelgrass is found on sandy substrates or in estuaries submerged or partially floating. Most Zostera species are perennial. They have long, bright green, ribbon-like leaves, about 1 cm wide. Short stems grow up from extensive, white branching rhizomes. The flowers are enclosed in the sheaths of the leaf bases, the fruits are bladdery and can float. Zostera beds are important for sediment deposition, substrate stabilization, as substrate for epiphytic algae and micro-invertebrates, and as nursery grounds for many species of economically important fish and shellfish. Zostera often forms these beds in bay mud in the estuarine setting. Zostera is able to maintain its turgor at a constant pressure in response to fluctuations in environmental osmolarity. It achieves this by losing solutes as the tide goes out and gaining solutes as the tide comes in.