Cnidaria, Anthozoa), with Emphasis on Deep-Water Species
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ResearchOnline@JCU This file is part of the following reference: Kitahara, Visentini Marcelo (2011) Morphological and molecular systematics of scleractinian corals (Cnidaria, Anthozoa), with emphasis on deep-water species. PhD thesis, James Cook University. Access to this file is available from: http://researchonline.jcu.edu.au/39370/ The author has certified to JCU that they have made a reasonable effort to gain permission and acknowledge the owner of any third party copyright material included in this document. If you believe that this is not the case, please contact [email protected] and quote http://researchonline.jcu.edu.au/39370/ CHAPTER 3 Diversity of deep-sea corals from New Caledonia: a central Pacific “hot spot” for azooxanthellate scleractinians Following extant zooxanthellate scleractinian diversity, the western Pacific is by far the most diverse region for azooxanthellate scleractinians in the world. Within this region, recent studies on species richness suggested that the Philippines azooxanthellate scleractinian fauna is the most diverse, totalling 157 species. However, literature review and examination of over 3000 specimens from New Caledonia (from 80-1200 m depth) revealed the occurrence of 170 species to this small southwestern Pacific Archipelago. Species rarefaction analysis for New Caledonian samples shows that the species diversity for this region still underestimated implying that this region has a much more diverse azooxanthellate scleractinian coral fauna than previously examined regions. Based on published taxonomic revisions, each of the 438 azooxanthellate scleractinians known to occur in the Western Pacific was scored for 8 geographical macroregions, resulting in a data matrix of 3440 cells. Zoogeographical affinities of these localities were determined by performing cluster analysis using unweighted pair-group average method (UPGMA), followed by a non-metric multi-dimensional ordination (MDS). Three major clusters were distinguished: (i) Australian; (ii) Philippines / Indonesia / Japan; and (iii) New Zealand / Australian eastern seamounts / New Caledonia / Vanuatu / Wallis and Futuna. The results presented herein corroborate with the idea that the submerged ridges and seamounts between New Zealand and New Caledonia function as conduits for deep-water coral migration, and advocate for the necessity for additional azooxanthellate scleractinian taxonomic revisions for other southern Pacific archipelagos. Chapter 3 Diversity of deep-sea corals from New Caledonia: a central Pacific “hot spot” for azooxanthellate scleractinians 3.1 INTRODUCTION Due to their capacity to deposit calcium carbonate, the corals of the order Scleractinia form some of the most three-dimensionally complex habitats in the ocean (Roberts et al., 2006). Known as shallow or deep-water reefs (see Roberts et al., 2009), these habitats sustain some of the most diverse ecosystems on the planet (Rogers, 1999; Dower & Perry, 2001; Reed, 2002). Comprising nearly 47% of the extant scleractinian species (Cairns, 2007; 2009), azooxanthellate corals do not live in association with photosynthetic dinoflagellates, being considered heterotrophic and usually referred as deep- or cold-water corals (Cairns, 2007). In contrast to their zooxanthellate shallow-water counterparts, azooxanthellate corals are ubiquitous in all oceans and are reported from off continental Antarctica (Cairns, 1982) to the Arctic Circle (Roberts et al., 2009). Amongst their representatives, many colonial and solitary species are considered cosmopolitan in distribution (e.g. Enallopsammia rostrata, Stenocyathus vermiformis, etc). Furthermore, the lack of symbiosis enabled azooxanthellate corals to thrive in aphotic regions, in waters deeper than 6300 m (Keller, 1976), with temperatures as low as -1ºC (Vaughan & Wells, 1943). Nonetheless, most azooxanthellate species live between 200 and 1000 m (Cairns, 2007), and the small number of azooxanthellate species inhabiting tropical shallow-water reef ecosystems is probably the result of their lack of competitiveness in relation to zooxanthellate species and the nutrient poor characteristic of these habitats. Interestingly, the comparison between species diversity from different ocean basins have shown that the most diverse region for both, zooxanthellate and azooxanthellate scleractinians, are located in the tropical western Pacific (Veron, 1995; Cairns, 2007). To date, there are about 438 azooxanthellate scleractinian species reported from the western Pacific, which represent nearly 61% of all known species of this “ecological” coral group. Within this region, the Philippines azooxanthellate coral fauna was purported to be the most diverse totalling 157 species (Cairns, 2007). Literature review and examination of nearly 3000 specimens from New Caledonia Exclusive Economic Zone (EEZ) (representing about 30% of the specimens collected to this region as explained in Chapter 2) resulted in the identification of 170 azooxanthellate scleractinians. Therefore, it is likely that New Caledonia represents the richest locality for this fauna worldwide. 336 Chapter 3 Diversity of deep-sea corals from New Caledonia: a central Pacific “hot spot” for azooxanthellate scleractinians In contrast to shallow-water zooxanthellate corals, to date only few studies have explored biogeographic patterns of azooxanthellate corals. Most of these studies had focused on Atlantic fauna (e.g. Cairns & Chapman, 2002; Dawson, 2002). Based on all previous records of azooxanthellate corals from western Pacific, a cluster analysis using unweighted pair-group average method (UPGMA) followed by a non-metric multi-dimensional ordination (MDS) presented herein, represents the first attempt to understand the zoogeographical affinities of the western Pacific azooxanthellate corals. In addition, even acknowledging that non-systematically sampling across different depths potentially included some bias into part of the analysis, a brief discussion of New Caledonian azooxanthellate corals distribution in correlation with potential abiotic factors such bathymetry, and other oceanographic aspects is also provided. 3.2 MATERIAL AND METHODS The present study is primarily based on the New Caledonian azooxanthellate scleractinian taxonomic review (Chapter 2), which comprised the examination of approximately 3000 previously unstudied specimens collected by French expeditions between 1985 and 2003 (Bathus 3, Bathus 4, Biocal, Gemini, Halical I, Halipro I, Musorstom 5, Musorstom 7, Musorstom 8, Musorstom 9, Norfolk 1, Norfolk 2, and SMIB 10). Collection of these specimens was carried out using waren-dredge and beam-trawl, between 80 and 1434 m (Fig. 3.1) across 178 stations (Chapter 2 – Tab. 2.2). The examined collection is a subset of the specimens sampled during those cruises, with thousands specimens still unstudied at French/New Caledonian Institutions (MNHN, Paris – Cairns and Bouchet, personnal communication; IRD, Nouméa – Pichon, personal communication). Based on previously published large taxonomic revisions (see section 3.3.2), the following 8 western Pacific macroregions were defined: (i) Japan; (ii) Philippines and Indonesia; (iii) New Caledonia; (iv) Vanuatu, and Wallis and Futuna Islands; (v) New Zealand; (vi) Northeastern Australia; (vii) Southeastern Australia; and (viii) Australia eastern seamounts (Fig. 3.2). The Australian eastern coast was divided in two regions (vi and vii - with boundary located between Queensland and New South Wales states) because it expands for 337 Chapter 3 Diversity of deep-sea corals from New Caledonia: a central Pacific “hot spot” for azooxanthellate scleractinians more than 30º of latitude and is influenced by different oceanographic conditions. A complete database (species presence/absence) of all azooxanthellate scleractinians reported from each one of the above 8 regions was assembled (data not shown) and used in the species richness estimators and zoogeographical analysis. Figure 3.1 –Map of the study area showing the stations with occurrence of azooxanthellate corals examined in the present study. Stations number are colour-coded based on the number of species identified: Black indicates 1 species; Gray indicates 2 to 5 species; Blue indicates 6 to 10 species; Green indicates 11 to 15 species; and Red indicates 16 or more species identified. For each one of the 8 defined regions species accumulation curves and species richness estimators were produced by randomly adding samples to the accumulation curve and then plotting the mean of the 999 permutations random drawings using the Primer ver.6 (Clarke & Gorley, 2006). Western Pacific azooxanthellate scleractinian zoogeographical affinities were analysed employing the same approach used by Cairns & Chapman (2002), by first 338 Chapter 3 Diversity of deep-sea corals from New Caledonia: a central Pacific “hot spot” for azooxanthellate scleractinians constructing a cluster analysis of the regions using a UPGMA, followed by a MDS, here using the software PAST ver. 1.89 (Hammer et al., 2001) and Raup-Crick and Simpson indices. According to Hurbalek (1982) and Hammer & Harper (2006) the similarity indices Dice, Jaccard, Simpson, Ochiai, Kulcynski, and Raup-Crick can be used for presence/absence data, although the Raup-Crick index is less affected by sampling bias (Gast et al., 2005), and the Simpson’s coefficient of similarity “is suitable when the sampling is considered to be incomplete” (Hammer & Harper, 2006: 212). Nonetheless, to test the groups retrieved from Raup-Crick