Taxonomy & Systematics: Understanding Seamount Biodiversity

Daniel M. Lauretta, PhD

Coastal ecosystems, platform, and deep-sea lab (Pablo E. Penchaszadeh, Director)

Museo Argentino de Ciencias Naturales Bernardino Rivadavia

Buenos Aires, Argentina

Our group of scientists, PhD students and undergraduates at the Argentinean Museum of Natural Sciences (Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” - CONICET) in Buenos Aires, Argentina work to investigate the taxonomy, systematics, biogeography and reproductive strategy for a wide range of deep-sea invertebrates. ¹ ² ³ We have particular expertise in cnidarians (sea anemones and cold-water corals), mollusks (snails, bivalves), echinoderms (crinoids, sea stars, brittle stars, sea urchins and sea cucumbers), and polychaetes. 

Our museum facilities support both morphological and molecular methods for taxonomic analysis, and the museum maintains an extensive repository of reference marine specimens. The museum team also works closely with other specialists and museum collections around the world.

The Global Seamounts Project (GSP) in development by Global Oceans plans to collect and analyze a wide range of biological samples from an intensive global field observation and sampling campaign on deep-sea seamounts; to conduct detailed taxonomic and phylogenetic analysis on collected and photographed samples, when possible; and to correlate these observations with estimates of species richness, abundance, diversity, biomass and other parameters that will populate a GSP portfolio of biophysical, ecosystem and niche models. Although the goal of the project is to identify specimens to the species level, the taxonomic resolution desired for the models will be defined by program modelers in a “data framework” document to be developed at an upcoming GSP Biophysical/Ecosystem Modeling Workshop.

Based on the scope and resolution of proposed datasets recommended from the modeling workshop, our group, together with other taxonomy and genomics experts, will develop a plan for the project that will include recommended taxonomic and classification strategies for specific types of ecosystem modeling inputs. For example, the initial GSP science plan proposes to characterize organisms at either the species, family-genus, or order-family level depending on the parameter being estimated (e.g. biomass), available methods, and the practical feasibility of analyzing collected or photographed specimens.

Based on the comprehensive range of environmental habitats and fauna represented by the GSP Working Groups, an important consideration will be how to approach the need for taxonomic expertise within each group. Our initial assumption is that some of this expertise will be readily embodied within some but possibly not all Working Groups. Highly diverse categories such as plankton, fish, and benthic invertebrates for example may require more extensive analysis that would benefit from specialized expertise.

Many species remain undescribed (Figure 1)⁶, so efforts to collect and describe new species need to be prioritized⁴. We have proposed that the GSP incorporate a Taxonomy & Systematics Working Group (Figure 2) that would conduct taxonomic analysis on behalf of all GSP Working Groups, as needed. 

Our group at the Argentinean Museum of Natural Sciences will work directly to support analysis of the benthic organisms within our range of expertise and we can coordinate with collaborating experts and institutions globally to access additional expertise as recommended by each Working Group.

Many organismic groups reveal, with careful analysis and usually with molecular data, cryptic species, sibling species, species complexes (which may be common in benthic invertebrates) and other complex characteristics ⁴ ⁵. The value of this level of species analysis for the ecosystem modeling work is yet to be determined, however the GSP presents a rare and valuable opportunity to conduct detailed taxonomic and systematics analysis using both molecular and morphological data over a geographically wide range of deep-sea seamounts and surrounding habitats, and to conserve specimens for future study. 

This Working Group will also be an excellent opportunity for students and early career scientists interested in deep-sea fauna.

A parallel GSP project for conducting detailed taxonomic work that will contribute to and extend the global deep-sea biodiversity database and literature is therefore proposed. We will explore these considerations and opportunities further at the upcoming GSP Workshops.

References:

1. Teso, Valeria, Diego Urteaga, and Guido Pastorino. "Assemblages of certain benthic molluscs along the southwestern Atlantic: from subtidal to deep sea." BMC ecology 19.1 (2019): 49.

2. Lauretta, D., and Martinez, M. "Corallimorpharians (Anthozoa: Corallimorpharia) from the Argentinean Sea." Zootaxa 4688.2 (2019): zootaxa-4688.

3. Penchaszadeh, Pablo E., Valeria Teso, and Guido Pastorino. "Spawn in two deep-sea volute gastropods (Neogastropoda: Volutidae) from southwestern Atlantic waters." Deep Sea Research Part I: Oceanographic Research Papers 130 (2017): 55-62.

4. Bickford, David, et al. "Cryptic species as a window on diversity and conservation." Trends in ecology & evolution 22.3 (2007): 148-155.

5. Brasier, Madeleine J., et al. "DNA barcoding uncovers cryptic diversity in 50% of deep-sea Antarctic polychaetes." Royal Society open science 3.11 (2016): 160432.

6. Martinez MI, Brogger MI (2012). Thandarum hernandezi, a new genus and new species of sea cucumber family Sclerodactylidae (Echinodermata: Holothuroidea: Dendrochirotida) from the Southwestern Atlantic Ocean. Zootaxa, 3304, 63-68.