A comparison of intertidal species richness and composition between Central California and Oahu, Hawaii

Abstract

The intertidal zone of tropical islands is particularly poorly known. In contrast, temperate locations such as California's Monterey Bay are fairly well studied. However, even in these locations, studies have tended to focus on a few species or locations. Here we present the results of the first broadscale surveys of invertebrate, fish and algal species richness from a tropical island, Oahu, Hawaii, and a temperate mainland coast, Central California. Data were gathered through surveys of 10 sites in the early 1970s and again in the mid‐1990s in San Mateo and Santa Cruz counties, California, and of nine sites in 2001–2005 on Oahu. Surveys were conducted in a similar manner allowing for a comparison between Oahu and Central California and, for California, a comparison between time periods 24 years apart. We report a previously undocumented richness of intertidal species in both locations: 516 for Oahu and 801 for Central California. Surprisingly, when differences in search efforts are controlled, overall (alpha) diversity appears to be similar between locations, although site level (beta) diversity is much higher in California. Species richness in California generally increased along a wave exposure gradient and distance from an urban area. Much higher numbers of both invasive and endemic species were found on Oahu. In California, more invertebrate species were found in the 1990s, likely due to an improvement in taxonomic resources since the 1970s, and species composition was different in the two surveys due to the high incidence of rare species. Although some southern species increased in number between the two time periods and some northern species decreased, we detected little evidence of change favoring southern or northern species. These results are in line with recent findings that water temperatures in the Monterey Bay have been in a cooling trend since the 1980s, in contrast to many locations elsewhere in the world.

Spatial and temporal variation of diverse inter‐tidal algal assemblages in Southwest O‘ahu

“…The influence of the shore physical features on the benthic community has been noted in previous studies of the Hawaiian rocky inter‐tidal by Zabin et al. (), Bird et al. (), Cox and Foster () and Cox, Smith, Popp, Foster, & Abbott ().…”

“…Zabin et al. () found differences in species diversity in contrasting habitats (bench and cobble rocky habitats). Bird et al.…”

“…Benthic assemblages among Hawaiian shores are quite variable. Smith (1992) found differences in macroalgal diversity among sites within a single island's inter-tidal habitat, and Zabin et al (2013) found that Hawaiian inter-tidal assemblages showed differences in species diversity with habitat type, such as bench or cobble rocky shoreline. A citizen scientist monitoring program has found remarkable broad-scale variability in benthic organism abundance and composition among 13 inter-tidal sites across the islands of O'ahu, Maui, Hawai'i and Moloka'i (Cox, Philippoff, Baumgartner, Zabin, & Smith, 2013).…”

First occurrence of the non-native bryozoan Schizoporella japonica Ortmann (1890) in Western Europe

“…the Monterey Bay area), S. errata, S. japonica, and S. pseudoerrata, the first two, at least, being introductions. Sorte et al (2010) listed an unidentified Schizoporella from Bodega Harbor, most likely S. japonica (see #21) but possibly S. errata, and Zabin et al (2012) recorded unidentified Schizoporella from two sites at Santa Cruz. Schizoporella pseudoerrata at present has a very localized confirmed distribution (Soule et al 1995) although it has been listed as present at two sites in the northern part of San Francisco Bay-Richmond Marina (Blum et al 2007) and Tiburon (Crooks et al 2011).…”

Local scale processes drive long‐term change in biodiversity of sandy beach ecosystems

“…Despite a growing number of local scale long‐term biodiversity studies (see Dornelas et al., ; Vellend et al., ), major gaps in the understanding of biodiversity change outside of developed nations and for underrepresented biomes seriously impede our ability to accurately quantify biodiversity change across the planet (Gonzalez et al., ). For example, only a few studies have assessed long‐term change in biodiversity for coastal ecosystems on a regional scale (e.g., Elahi et al., ; Novoa, Talley, Talley, Crooks, & Reyns, ; Smith, Fong, & Ambrose, ; Zabin et al., ) and none of these studies have addressed diversity change for sandy beach ecosystems, which dominate shorelines globally making up ~70% of open coasts (Schoeman et al., ).…”