Strong Depth-Related Zonation of Megabenthos on a Rocky Continental Margin (∼700–4000 m) off Southern Tasmania, Australia

Assemblages of megabenthos are structured in seven depth-related zones between ~700 and 4000 m on the rocky and topographically complex continental margin south of Tasmania, southeastern Australia. These patterns emerge from analysis of imagery and specimen collections taken from a suite of surveys using photographic and in situ sampling by epibenthic sleds, towed video cameras, an autonomous underwater vehicle and a remotely operated vehicle (ROV). Seamount peaks in shallow zones had relatively low biomass and low diversity assemblages, which may be in part natural and in part due to effects of bottom trawl fishing. Species richness was highest at intermediate depths (1000–1300 m) as a result of an extensive coral reef community based on the bioherm-forming scleractinian Solenosmilia variabilis. However, megabenthos abundance peaked in a deeper, low diversity assemblage at 2000–2500 m. The S. variabilis reef and the deep biomass zone were separated by an extensive dead, sub-fossil S. variabilis reef and a relatively low biomass stratum on volcanic rock roughly coincident with the oxygen minimum layer. Below 2400 m, megabenthos was increasingly sparse, though punctuated by occasional small pockets of relatively high diversity and biomass. Nonetheless, megabenthic organisms were observed in the vast majority of photographs on all seabed habitats and to the maximum depths observed - a sandy plain below 3950 m. Taxonomic studies in progress suggest that the observed depth zonation is based in part on changing species mixes with depth, but also an underlying commonality to much of the seamount and rocky substrate biota across all depths. Although the mechanisms supporting the extraordinarily high biomass in 2000–2500 m depths remains obscure, plausible explanations include equatorwards lateral transport of polar production and/or a response to depth-stratified oxygen availability

A redescription of Anthomastus agius Tixier-Durivault with a generic placement in Sinularia (Coelenterata: Octocorallia), and some remarks on Sinularia ramosa Tixier-Durivault

Volume: 11Start Page: 133End Page: 13

Molecular Systematics of the Speciose Indo-Pacific Soft Coral Genus, Sinularia (Anthozoa: Octocorallia).

The speciose tropical soft coral genus Sinularia traditionally has been divided into five intrageneric taxonomic groups based on variation in a single morphological character: the shape of the club sclerites (calcite skeletal elements) embedded in the surface tissues of the colony. To test the phylogenetic utility of this system of classification, we used a 735-bp fragment of the octocoral-specific mitochondrial msh1 gene to construct a molecular phylogeny that included 80 of the ∼150 recognized morphospecies of Sinularia. The msh1 phylogeny recovered five well-supported clades, but they were not congruent with the traditional intrageneric taxonomic groups. Mapping of characters onto the tree suggested that the five major clades plus several additional sub-clades of Sinularia can be distinguished based on a suite of four morphological characters; these include the presence of sclerites in the tentacle, collaret, and point regions of the polyps, in addition to the shape of the club sclerites in the surface tissues. The overall growth form of the colony also distinguishes some clades. Polyp sclerites have for the most part been overlooked taxonomically in Sinularia, and as a result information on these characters is lacking or is incorrect in many species descriptions. As has been the case in other recent studies of lower metazoan groups, construction of a molecular phylogeny has led us to recognize the phylogenetic and taxonomic importance of previously overlooked morphological characters. A revised taxonomic key that includes these characters is already improving our ability to discriminate species boundaries, and facilitating description of new Sinularia species

Early development and coloniality in Oligophylloides from the Devonian of Morocco—Are Heterocorallia Palaeozoic octocorals?

Heterocorals represent an enigmatic group of Palaeozoic corals, known from relatively short time intervals in the Devonian and Carboniferous periods. The major differences between Heterocorallia and other Palaeozoic corals are the lack of an external theca (epitheca), lack of calices and the presence of dichotomously dividing septa-like structures. Heterocoral skeleton was presumably externally covered by the soft tissue and each branch of their skeleton has, until now, been regarded as a corallite–a skeleton of a single polyp. We investigated upper Famennian Oligophylloides from Morocco, focussing on branching processes, wall structure, previously poorly known initial growth stages and the growing tip, described here for the first time. We demonstrate that Oligophylloides shows a unique colony development not known in any group of anthozoans possessing a septate-like architecture and suggest that the previously postulated homology between true septa in hexa- and rugose corals on one hand, and Oligophylloides on the other, must be rejected. Based on the skeleton structure and branching patterns, we postulate, contrary to former ideas, that the stem and branches of heterocorals represent the skeleton of a multi-polyp colonial coral, similar to many extant octocorals. We found numerous potential homologies with octocoral skeletons (notably the Keratoisidinae within the Isididae) and, as a result, we propose the inclusion of the order Heterocorallia within the subclass Octocorallia. This suggestion requires, however, further research on the other taxa of heterocorals. We also propose some changes to the morphological terminology for the Heterocorallia

Early development and coloniality in Oligophylloides from the Devonian of Morocco—Are Heterocorallia Palaeozoic octocorals?

Heterocorals represent an enigmatic group of Palaeozoic corals, known from relatively short time intervals in the Devonian and Carboniferous periods. The major differences between Heterocorallia and other Palaeozoic corals are the lack of an external theca (epitheca), lack of calices and the presence of dichotomously dividing septa-like structures. Heterocoral skeleton was presumably externally covered by the soft tissue and each branch of their skeleton has, until now, been regarded as a corallite–a skeleton of a single polyp. We investigated upper Famennian Oligophylloides from Morocco, focussing on branching processes, wall structure, previously poorly known initial growth stages and the growing tip, described here for the first time. We demonstrate that Oligophylloides shows a unique colony development not known in any group of anthozoans possessing a septate-like architecture and suggest that the previously postulated homology between true septa in hexa- and rugose corals on one hand, and Oligophylloides on the other, must be rejected. Based on the skeleton structure and branching patterns, we postulate, contrary to former ideas, that the stem and branches of heterocorals represent the skeleton of a multi-polyp colonial coral, similar to many extant octocorals. We found numerous potential homologies with octocoral skeletons (notably the Keratoisidinae within the Isididae) and, as a result, we propose the inclusion of the order Heterocorallia within the subclass Octocorallia. This suggestion requires, however, further research on the other taxa of heterocorals. We also propose some changes to the morphological terminology for the Heterocorallia

Physiologizing (In)fertility in the Roman World: Lucretius on Sacrifice, Nature, and Generation

The present paper reassesses the intellectual background of Lucretius\u2019 treatment of infertility in 4.1233-1241, pointing out the author\u2019s ability to combine genuine Epicurean doctrine and Roman cultural patterns. Lucretius\u2019 denigration of religious mentality and his efforts to offer an entirely rational explanation of (in)fertility are interpreted in light of both internal evidence in the De Rerum Natura (e.g. 1.1-20; 248-264; 2.581- 660) and differents kinds of external evidence - including the so-called Laudatio Turiae, Rome\u2019s fertility cults, and underused Epicurean sources such as PHerc 908/1390. Indeed, while systematically delegitimizing the traditional connection between supernatural powers and generation, the poet endeavors to convert his readers to a comprehensive Epicurean worldview in which death and birth, fecundity and sterility, reflect the existence of a material \u2018great chain of being\u2019

Number of individuals and number of identifiable taxa per image (minimum, maximum and mean values for both), total number of species recorded and diversity (H′) for images binned into 100 m depth strata.

<p>Number of individuals and number of identifiable taxa per image (minimum, maximum and mean values for both), total number of species recorded and diversity (H′) for images binned into 100 m depth strata.</p

Representative images of the biotic zones on the Tasmanian seamounts.

<p>a. Hormathiid-dominated volcanic rock, at 2400 m. The rubble surrounding the rock is predominantly shell plates of deep-sea barnacles. Live barnacles are visible as white objects amongst the greenish-brown anemones, and to the left, a branching Isidid colony. For scale, the anemones are about 5 cm in diameter. b. Reef-scape at 2600 m, showing the dominance of live and recently dead (white skeletons) gorgonians, most apparently in the genus <i>Isidella</i>. Hormathiids (greenish brown) and barnacles (white) are visible on the rock, along with a glass sponge (Hexactinellid) to the left. Note the hormathiids attached to the up-right dead coral skeletons. c. Deep barren volcanic rock at 2820 m. The laser points are 10 cm apart. d. Interface between deep rock and sand plain at 3990 m. All photos were taken on <i>Jason</i> dive 392.</p