Checklist of marine benthic green algae (Chlorophyta) on Hainan, a subtropical island off the coast of China: comparisons between the 1930s and 1990–2009 reveal environmental changes

Abstract

A complete checklist of intertidal to shallow subtidal marine green seaweeds (Chlorophyta) growing on the subtropical island of Hainan (China) is presented here for the first time. It covers data from extensive recent (1990–2009) and historical (1933–1935) collections, and additional published records from various time periods. Data were analyzed by time period. We postulate that environmental changes on Hainan Island documented since the 1980s (e.g., degradation of coral reefs, development of tourism and mariculture farms) are reflected in the green algal species complement and in the dominance or absence of specific algal groups during different time periods. In total, 105 green algal taxa were recorded, including 37 new to Hainan Island, and 18 new records for China. There was a clearly evident change in floristic composition between early and recent collections. In the 1930s, there was a dominance of Caulerpaceae, Codiaceae and Cladophoraceae. By 1990/1992, the numbers of Ulvaceae had increased 1.6-fold and numbers of Cladophoraceae 1.7-fold. Both families contain many opportunistic species that prefer nutrient-enriched or degraded environments. At the same time, species richness of Codiaceae, Caulerpaceae and Udotaceae, families with complex thallus structures, decreased considerably. The floristic differences between the 1990/1992 and 2008/2009 collections were minor.

Macroalgal assemblage changes on coral reefs along a natural gradient from fish farms in southern Hainan Island

“…Freshly collected material was identified using monographic publications, floristic studies and systematic articles (Titlyanov et al, 2011b(Titlyanov et al, , 2012(Titlyanov et al, , 2014a. The systematics and nomenclature followed Guiry and Guiry (AlgaeBase, searched 2015).…”

“…Significant differences in species richness and composition of marine macrophytes were found in the algal collections from the 1930-1970's and 1990/1992 and then 2008-2010, probably as a consequence of coral reef degradation and pollution of the sea by mariculture waste (Zhang et al, 2006;Huang et al, 2013;Hughes et al, 2013;Li et al, 2015). It is known that degradation processes on coral reefs are frequently associated with changes in macroalgal assemblages (Lapointe, 1997;Diaz-Pulido and McCook, 2002;Titlyanov and Titlyanova, 2008;Titlyanov et al, 2011b).…”

The Significance of New Records of Benthic Red Algae (Rhodophyta) for Hainan Island (and China) between 1990 and 2016

“…A third sampling was performed during 2008-2016 (LC) (Figure 1). Some of the results of this algal inventory have also been published [13][14][15]17,19,20], with 301 species being recorded including 163 (54%) Rhodophyta, 50 (17%) Phaeophyceae, and 88 (29%) Chlorophyta. This further paper presents an annotated list of new findings of red algae for Hainan Island made during the course of this study.…”

“…This collection has been deposited in the herbarium of the Institute of Oceanology of the Chinese Academy of Sciences [12]. All records based on these collections were considered in our previous papers [13][14][15][16][17][18]. In this early collection (EC), a total of 310 macroalgal taxa and their forms were found, of which 178 species (57%) were Rhodophyta (Rh), 64 (21%) Phaeophyceae (Ph), and 68 (22%) Chlorophyta (Ch).…”

“…The next major algal sampling on Hainan was conducted in 1990 and 1992 during the German-Chinese expeditions (IC) to Hainan Island ( Figure 1). The results of these expeditions were partially published [13,[16][17][18], with 203 taxa collected, including 105 red (52%), 32 brown (16%), and 66 green (32%) algal taxa. A third sampling was performed during 2008-2016 (LC) (Figure 1).…”