TheUlvaspp. Conundrum: What Does the Ecophysiology of Southern Atlantic Specimens Tell Us?

Vinícius Peruzzi Oliveira,Nuno Tavares Martins,Barbara Lage Ignacio,Leticia Dobler,Alex Enrich-Prast

doi:10.1155/2019/5653464

Abstract

Species of the genusUlvaare common in anthropogenically disturbed areas and have been reported as the cause of green tides in many areas of the world. In addition, they rank among the main marine groups used in a wide range of commercial applications. By displaying few distinctive morphological characters, some taxonomical identifications are difficult and the genus is under a conundrum. Our aims were to provide ecophysiological information about threeUlvaspecies in response to abiotic factors and to evaluate the proposal of ecophysiological information and the chlorophyll-afluorescence technique as auxiliary tool to resolve the long-standing taxonomic confusion. We hypothesize that three cooccurring specimens (U. fasciataDelile,U. lactucaLinnaeus, andU. rigidaC. Agardh) have different ecophysiological responses (as measured by the effective quantum yield of photosystem II by pulse amplitude modulated fluorometers) under manipulated conditions of temperature and nutrient concentration.Ulva lactucaandU. rigidashowed different photosynthetic efficiencies related to temperature, whereas no difference was recorded forU. fasciataindividuals. These results provide a reasonable explanation for the variability in spatial and temporal abundance of these species ofUlvaon rocky shores. We proposed the use of ecophysiological information by chlorophyll-afluorescence as an auxiliary tool to corroborate the taxonomic distinction ofUlvaspecies. We reinforce the statement ofU. fasciataandU. lactucaas distinct valid species.

Highlights

The genus Ulva (Chlorophyta) comprises cosmopolitan macroalgae that inhabit a gradient from freshwater to fully saline shallow environments [1]
Ulva is one of the genera involved in a taxonomic conundrum that entangles morphological or molecular data for species identification, mainly involving distinction around U. lactuca and U. fasciata
In spite of the undeniable contribution of molecular methods to taxonomy, there is no easy way to determine the accurate match between the GenBank sequences and the Journal of Marine Biology morphological characterization of most studies, which has led to uncertainty and sometimes to misinterpretation

Summary

Introduction

The genus Ulva (Chlorophyta) comprises cosmopolitan macroalgae that inhabit a gradient from freshwater to fully saline shallow environments [1]. Species of this genus rank among the first species to be established in disturbed environments because of their morpho-physiological features, that allow tolerance to wide range of environmental conditions [2,3,4]. Ongoing advances in molecular biology have driven taxonomic revisions, and morphological features have lost credibility as the primary species delimitation criterion for many groups (see [9] for algae). In spite of the undeniable contribution of molecular methods to taxonomy (see [14,15,16,17]), there is no easy way to determine the accurate match between the GenBank sequences and the Journal of Marine Biology morphological characterization of most studies, which has led to uncertainty and sometimes to misinterpretation (see [1, 11])

Objectives

Methods

Conclusion