Document Type

Article

Publication Title

Florida Scientist

Abstract

The Indian River Lagoon System (IRL) is regarded as having a high level of biodiversity. The level of biodiversity is often attributed in part to the 2-degree latitudinal span (251 km) of the IRL and to its position in a transitional zone between tropical and temperate biotic provinces. This hypothesis was tested for submerged aquatic vegetation (SAV) based on a recent treatise (Littler, Littler, and Hanisak, 2008). Five of seven species of seagrass are tropical, and two have either a broad or very narrow latitudinal distribution; the transition-zone hypothesis does not hold for seagrasses. Most macroalgae (131 spp.) are tropical/subtropical; 73 species are widely distributed from temperate/boreal to tropical/subtropical latitudes and do not contribute to a Transition-Zone Hypothesis; and 8 species from higher latitudes range southward to the IRL region. Two-thirds of the 221 SAV species form a zone of overlap in the IRL, of which 61.5% are of tropical/subtropical origin. Several groups of IRL plants and animals reported in the literature are also primarily tropical/subtropical with smaller contributions from temperate regions, providing further support for the Transition Zone Hypothesis. But the possible retraction of temperate species with climate change might eliminate the IRL as a zone of transition.

First Page

125

Last Page

135

DOI

10.70931/8804/MUFC8959

Publication Date

12-2025

Comments

This published article is made available in accordance with publisher’s policy. It may be subject to U.S. copyright law.

Supplemental Data can be found in the repository, "Indian River Lagoon Transition Zone Hypothesis Database" by Richard L. Turner

Download

Share

COinS