Topical Collections

Read the Topical Collection Biodiversity of Icelandic Waters

Read the Topical Collection Interstitial and Cave Diversity in Atlantic Oceanic Islands

Coming soon:
Systematics and Biodiversity of Indian Ocean Sharks, Rays, and Chimaeras (Chondrichthyes)
The Indian Ocean, especially the Western Indian Ocean, is a biodiversity “hotspot” holding one of the most diverse Chondrichthyan fauna’s globally with >400 species, of which 22 new species have been described since 2016; this represents ~34% of all new species named during this period. The region also has a high degree of endemism, with 60+ species, many of which have very restricted geographic ranges. The number of new Indian Ocean species being discovered does not appear to show any signs of slowing, with additional new species currently under investigation, especially deep-sea species. This topical collection issue focuses on the rich biodiversity of Indian Ocean sharks, rays, and chimaeras, with the aim of clarifying the taxonomic status and descriptions of new shark, ray, and chimaera species. 

Editors:
David A. Ebert, debert@mlml.calstate.edu, Pacific Shark Research Center, Moss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, 95039, California, USA
David A. Ebert, Research Associate, South African Institute for Aquatic Biodiversity, Grahamstown, South Africa
David A. Ebert, Research Associate, Department of Ichthyology, California Academy of Sciences, San Francisco, USA 
Simon Weigmann, simon.weigmann@elasmo-lab.de, Elasmo-Lab, Elasmobranch Research Laboratory, Georg-Bonne-Str. 83, 22609 Hamburg, Germany
Simon Weigmann, Associated Scientist, Center of Natural History, University of Hamburg, Martin-Luther-King-Platz 3, 20146 Hamburg, Germany. 
William T. White, william.white@csiro.au, CSIRO Oceans & Atmosphere, National Research Collections Australia-Australian National Fish Collection, GPO Box 1538, Hobart, Tasmania, 7001, Australia

Coming soon:
Interstitial and cave diversity in Atlantic Oceanic Islands
Editor: Alejandro Martínez

The Atlantic is the second largest ocean on Earth, forming an elongated basin limited by the Arctic Ocean in the north and Antarctica in the south. It was originated after the break-up of Pangaea, and today continues to spread along the Mid-Atlantic Ridge, a submarine mountain chain that divides the Atlantic into an eastern and a western basin. The Atlantic harbors several oceanic islands, mostly of volcanic origin, scattered from polar to tropical latitudes. Some of these islands are grouped in archipelagos, such as Faroe Islands, Azores, Madeira, Selvagens Canary Islands, Cabo Verde, Gulf of Guinea Islands, Saint Peter and Paul Rocks, Fernando de Noronha, and, Trinidade & Martin Vaz; while others stand alone, Bermuda, Ascension, St. Helena, Tristan da Cunha, and Gough (Gillespie and Clague 2009). Atlantic Oceanic islands present varying levels of isolation, as well as very different ecological conditions and geological histories depending on their location and age, which ranges between 29.5 ma in Selvagens to 3.7 in Trinidade & Martin Vez. This variation makes them interesting systems to understand ecological and evolutionary processes (Ávila et al. 2018). Many Atlantic Oceanic islands have been highlighted as biological hotspots, hosting relevant species both from biogeographical and evolutionary perspectives, as well as unique ecological assemblages characterizes by comparatively high endemism compared to their nearest mainland. Early studies focused on terrestrial ecosystems, but an increasing number of publications have concentrated on the open marine habitats. However, studies on marine interstitial and cave ecosystems (including crevicular habitats), are rarer and focused only in some of the islands.
Cave and crevicular ecosystems include extensive anchialine systems, such as Canarian lava tubes (Martínez and Gonzalez 2018), Bermudian extensive karstic caves (Iliffe et al. 1983), and lava pools and crevices in Ascension and Iceland; as well as marine caves, studied so far in Fernando de Noronha, Cabo Verde, Madeira, Selvagens, and Azores (Calado et al. 2004; Micael et al. 2006; Domingos 2013). Endemic species of annelids, copepods, shrimps, thermosbaenaceans, and even, remipedes, are known from some of these habitats (Gerovasileiou et al. 2016). Interstitial ecosystems, in contrast, are widely distributed along these archipelagos, represented by the spaces amongst the sand grains. Whereas they are expected to be poor in species diversity due to their distance from the continent and lack of dispersal forms of many interstitial species (Sterrer 1973), preliminary studies have instead highlighted a surprisingly high diversity of species (Martínez et al. in review).
The goal of this topical collection is to mainly promote research on marine biodiversity in cave and interstitial ecosystems in Atlantic oceanic at three levels: (1) description of new species; (2) ecological studies that might help to infer local and regional distribution patterns and its correlates; (3) inference of processes producing the observed patterns, using phylogenetic tools. The overall goal is to fill our gap on knowledge in these habitats, but also to improve our understanding of colonization processes of partially isolated habitats, including the role of Atlantic Oceanic islands in trans-Atlantic dispersal of marine species. Contributions focusing on Atlantic Oceanic islands along with other archipelagos or continental zones, are also accepted within this topical collection.

Ávila SP, Cordeiro R, Madeira P, et al (2018) Global change impacts on large-scale biogeographic patterns of marine organisms on Atlantic oceanic islands. Marine Pollution Bulletin 126:101–112. doi: 10.1016/j.marpolbul.2017.10.087

Calado R, Chevaldonne P, Dos Santos A (2004) A new species of the deep-sea genus Bresilia (Crustacea: Decapoda: Bresiliidae) discovered from a shallow-water cave in Madeira. Journal of the Marine Biological Association of the UK 84:191–199

Domingos C FernandoMuricy, Guilherme (2013) Four new species of Plakinidae (Porifera: Homoscleromorpha) from Brazil. Zootaxa 3718:530. doi: 10.11646/zootaxa.3718.6.2

Gerovasileiou V, Martínez A, Álvarez F, et al (2016) World Register of marine Cave Species (WoRCS): a new Thematic Species. Database for marine and anchialine cave biodiversity. Research Ideas and Outcomes 2:e10451

Gillespie RG, Clague DA (eds) (2009) Encyclopedia of islands. University of California Press, Berkeley

Iliffe TM, Hart CWJ, Manning RB (1983) Biogeography and the caves of Bermuda. Nature 302:141–142

Martínez A, Di Domenico M, Leasi F, et al (in review) Patterns of diversity and endemism of soft-bodied meiofauna in an oceanic island, Lanzarote, Canary Islands. Marine Biodiversity

Martínez A, Gonzalez BC (2018) Volcanic Anchialine Habitats of Lanzarote. In: Moldovan OT, Kováč Ľ, Halse S (eds) Cave Ecology. Springer International Publishing, Cham, pp 399–414

Micael J, Azevedo JM, Costa A (2006) Biological characterisation of a subtidal tunnel in São Miguel island (Azores). Biodiversity & Conservation 15:3675–3684

Sterrer W (1973) Plate tectonics as a mechanism for dispersal and speciation in interstitial sand fauna. Netherlands Journal of Sea Research 7:200–222