Uncovering mollusk diversity in mangrove forests

Tricia C. Goulding

Onchidiidae slug

Pennsylvania State University
Department of Biology

2nd place winner of the best student presentation award at the 

American Malacological Society

This past week I joined other mollusk researchers to exchange ideas, discuss challenges in the field, and learn from each other’s research at the annual meeting of the American Malacological Society. I was able to attend to present my dissertation research on mangrove gastropods in the Indo-West Pacific. I enjoyed meeting many eminent malacologists, as well as the other students, during our week of activities.

The snails and slugs I study live in tropical mangrove forests, a threatened estuarine habitat. Mangrove forests are cut down across the Indo-West Pacific to produce shrimp ponds, or for firewood and building materials. The loss of mangroves leaves coastlines vulnerable to storms, and results in declining habitats for fish and shellfish which support wild fisheries. Gastropods are an important component of mangrove ecosystems, but the species diversity across the Indo-West Pacific is still poorly known. In order to better understand the species diversity in mangroves, I have explored hundreds of mangroves with collaborators from 10 countries and collected samples of snails and slugs. I extracted DNA from these samples and sequenced a fragment of DNA known as a “DNA barcode,” which is useful in many groups of animals to differentiate species. I used this data to get a better understanding of species richness across the Indo-Pacific. Specifically, I have estimated that the area with the highest number of mangrove gastropod species is found in a region commonly called the Coral Triangle (a region encompassing Indonesia and the Philippines). Interestingly, this data also shows that the South China Sea (between Singapore, Sumatra, Borneo and Vietnam) is also a significant hotspot for diversity in mangrove gastropods, and that many of the species in this region are unique from the fauna of the Coral Triangle.

After estimating species richness, the next step to understanding mangrove ecosystems is to identify the species and to describe the new species. I have been working on re-describing the onchidiid slugs and classifying the species into genera using modern microscopy and DNA sequences. Most of the diversity within the family Onchidiidae is in the tropical Indo-West Pacific (from eastern Africa to the Pacific Islands). However, original species descriptions, mostly from the 1800s to 1930s, often did not include information on the habitat of these slugs or their appearance when alive, which are important characteristics used for identification. In addition, museum collections contain very few of these slugs because mangroves have rarely been explored (possibly because of the other fauna in mangroves: mosquitos, snakes and crocodiles!).

 
By collecting new samples from across the Indo-West Pacific, our lab has been able to record important natural history information, photograph live animals in the field, and preserve tissue samples for DNA analysis. These new collections have been invaluable in studying the diversity of this group, and have resulted in the identification of 40 new species of slugs! Onchidiid slugs are very abundant in intertidal ecosystems, and it is only after we have identified the species present and their distribution that other researchers will be able to study their role in mangrove ecosystems.

American Malacological Society 83rd Annual Meeting Summary

Charles Lydeard, Elizabeth K. Shea, and Amanda Lawless

The American Malacological Society recently held its 83^rd annual meeting this past July at Clayton Hall of the University of Delaware, Newark, Delaware.  The meeting was hosted by AMS President Liz Shea of the Delaware Museum of Natural History.  The formal meeting was preceded with a workshop organized by Petra Sierwald, Rüdiger Bieler, Gary Rosenberg and Liz Shea and sponsored by an iDigBIo Conference Award entitled Digitizing the 2^nd largest Invertebrate Phylum: Mollusks.  The meeting kicked off with the President’s Symposium, which continued along with the workshop theme Mollusk research in a digital world: creating, integrating and mining large datasets and had presentations by Bieler et al., Rosenberg and Khoo, Vendetti et al, Zigler, and Vecchione.  José Leal organized a symposium entitled Mollusks in Peril and Heather Judkins organized one entitled Cephalopod Biodiversity.  The meeting had nearly 100 registered participants and the talks were all well attended including sessions on biodiversity with several presentations including one on malacology underground by Gladstone et al.; Phylogeny & Systematics with several presentations including one by Graf; Mollusk Collections with one by Callomon; Dispersal, Feeding Strategies, and Historical Ecology.  The evenings were also terrific opportunities to continue interacting with friends and colleagues including the reception at Stone Balloon on Main Street, an Auction, and an excellent cookout, which was held at the Delaware Museum of Natural History.  Field excursion opportunities also were provided for those who were able to stay the day after the meetings.  All in all, it was a terrific meeting and a great time for all. 

If you couldn’t make this meeting, perhaps you can go next year when, the meeting will be hosted by AMS President 2017-2018, Norine Yeung of the Bernice Pauahi Bishop Museum in Hawaii.  See you there!