Effect of depth gradient and temperature on Zostera marina vegetative and reproductive phenology in the first year of the 1997–1998 El Niño

Alf E Meling-López ,Adriana Leticia Navarro-Verdugo,Horacio De La Cueva,Pedro Ortega-Romero,Silvia E Ibarra-Obando

doi:10.7773/cm.v47i1.3101

Abstract

Does Zostera marina exhibit phenotypic plasticity, maximizing fitness in traits responding to environmental factors, i.e., depth and temperature? We compared the vegetative and sexual phenology and reproductive effort of Z. marina by analyzing vegetative and reproductive shoot density, biomass, and reproductive stages to determine structural features of vegetative and reproductive shoots from subtidal and intertidal environments in San Quintín Bay, Baja California, a year before and after the 1997–1998 El Niño/Southern Oscillation (ENSO). We found significant differences in vegetative and reproductive biomass between intertidal and subtidal environments driven by temperature differences between ENSO and non-ENSO years. Subtidal plants had lower density of long reproductive shoots and a shorter reproductive cycle. Seed release occurred from May to October in the subtidal environment, and from May to November in the intertidal environment. Maximal recorded values were 219.5 (±45.8) seeds per reproductive shoot in the subtidal environment and 151.3 (±21.5) in the intertidal environment. We observed higher sexual activity and lower vegetative biomass in the intertidal environment, the most stressful environment. Both vegetative and reproductive biomass were affected by the increase in temperature during ENSO, but vegetative and reproductive shoot densities were not affected.

Highlights

Characterized by high growth dynamics and plasticity, Zostera marina is the most widely distributed and abundant marine plant in the Northern Hemisphere (Lee et al 2006)
San Quintín Bay (SQB) was impacted by the 1997–1998 El Niño/Southern Oscillation (ENSO) event, the most drastic ENSO event recorded in modern history (Kumar et al 2001)
We recorded a 1.5 oC increase in sea surface temperature in 1997 in SQB with respect to 1996. This increase is higher than the 0.25 oC increase measured during other ENSO events (Trenberth et al 2002)

Summary

Introduction

Characterized by high growth dynamics and plasticity, Zostera marina is the most widely distributed and abundant marine plant in the Northern Hemisphere (Lee et al 2006). It is found along the Pacific coast of North America, from the temperate Alaska coastal waters to the hot waters Introducción. Zostera marina grows in shallow bays, coastal lagoons, and estuaries, in subtidal and intertidal environments (Riosmena-Rodríguez et al 2013). The subtidal environment is more stable (Lee et al 2006); here stress is caused by light penetration as a function of depth, illumination, and water turbidity (Nielsen et al 2002)

Methods

Results

Conclusion