World Congress of Malacology Antwerp ... - Unitas Malacologica

Complementarity within a functional group of filter-feeding freshwater mussels influences
stream foodwebs
Vaughn, Caryn C.; Spooner, Daniel E.; Galbraith, Heather S.
Oklahoma Biological Survey and Department of Zoology, University of Oklahoma,
Norman, OK 73019, USA,
Email: cvaughn@ou.edu
This study examined the influence of biodiversity on ecosystem function within a trait-based
functional group, freshwater mussels, and asked if biodiversity effects varied with environmental
context and species composition. We conducted a manipulative field experiment examining the
effects of freshwater mussel assemblages varying from one to four species on periphyton biomass
and invertebrate grazer abundance on mussel shells across two sets of seasonal environmental
conditions, moderate flow and water temperature (fall) and severely reduced flow combined with
high water temperature (summer), in a small river in the southcentral U.S. Biodiversity effects varied
with species composition, environmental context, and across trophic levels. Algal biomass was
influenced most strongly by trait-independent complementarity. This effect was evident in both
seasons, but was strongest in summer, and is likely due to differences between species in N:P
excretion rates in summer when nutrients are limiting. Invertebrate grazer densities were also
influenced most strongly by trait-independent complementarity, but biodiversity effects were more
complex than for algal biomass. Grazer densities were likely influenced by a combination of varying
algal abundance and shell morphology between mussel species. In this study, biodiversity effects
extended across trophic levels, but in general were non-additive and not predictable across trophic
levels. This study shows that the strength of biodiversity effects, and underlying mechanisms, can
vary with environmental context.
Molluscs of the infra- and circalittoral of the Azores:
The story of a field-trip of an undergraduate Malacology class
Velosa, Ana 1 ; Lopes, Tiago 1 ; Fiedler, Maria 1 ; Arruda, Rafael 1 ; Souza, Maria 1 ; Furtado,
Cláudia 1 ; Ponte, Alexandra 1 ; Moura, João 1 ; Martins, António M. de Frias 2
1. Departamento de Biologia, Universidade dos Açores, 9501-855 Ponta Delgada, Açores, Portugal,
Email: jimileca@gmail.com; tiago_lopes@linus.uac.pt; nanda_fiedler@yahoo.com.br;
rafael_arruda@linus.uac.pt; nana.ssouza@hotmail.com; claudia_furtado@linus.uac.pt;
aponte@linus.uac.pt; joaomoura14@hotmail.com
2. CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos – Pólo Açores, e
Departamento de Biologia, Universidade dos Açores, 9501-855 Ponta Delgada, Açores, Portugal,
Email: frias@notes.uac.pt
The Mollusca are very diversified in their external appearance and ways of life; octopuses and clams,
limpets and snails, however, share a common structural plan. Such high diversity and tight
phylogenetic relationship makes them privileged models for the study of evolution. Concurrently,
knowledge of the local fauna is needed to understand patterns resulting from evolution and the
processes leading to it; these themes are discussed in Malacology, an undergraduate level discipline
offered at the University of the Azores. The Azorean circalittoral is underrepresented in studies
dealing with the marine fauna of the archipelago, the stress having been put historically on the nearshore
and deep-sea faunas. During the school year 2006/2007 and on the wake of the 3 rd International
Workshop of Malacology and Marine Biology conducted at Vila Franca do Campo (2006), part of the
course’s field-work dealt with aspects of the circalittoral malacofauna. Taking advantage of acquired
expertise and stored facilities during the workshop, collecting with dredge and grab off Vila Franca
do Campo was done at depths 30 to 50 meters; the material was kept alive in the laboratory until
sorted and the animals photographed. Seventy-four species were recorded. Many empty shells were
dredged, some of species from neighbouring hard-bottoms, most apparently from mixed substrate,
thus making it difficult to assess the real biology of the explored area. The sandy bottom was
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