Klaus Ruetzler. A tribute


One need not be born at the edge of the sea to become an eminent marine scientist. Like Louis Agassiz, Jacques Picard, Albert Defant, Pierre Tardent or his mentor Rupert Riedl, Klaus Ruetzler was born in a landlocked country, specifically in the alpine Tyrol province of Austria in 1936. When his family moved to Vienna, he studied biology, anthropology, psychology and philosophy at the University of Vienna. His PhD thesis dealt with the systematics and ecology of sponges in Mediterranean submarine caves. With his teacher Rupert Riedl, he shared the adventurous spirit which led them to venture into the sea with diving gear to explore otherwise inaccessible habitats, and to travel to exotic places. Both these endeavours were not trivial in post-war Europe, and the equipment used and the conditions of travelling were very primitive compared to the luxury available to the millions of diving tourists (and the scores of diving scientists) today. Even before obtaining his PhD in 1963, Klaus – together with Ernst Kirsteuer (later curator at the American Museum of Natural History, New York) – undertook an expedition to Madagascar, where they spent 10 months in a makeshift research lab in 1959.

I, Joerg, met Klaus, who is a few years my senior, just as he was preparing to leave for the United States to become a curator at the National Museum of Natural History in Washington, DC (Fig. 1). In fact, I was honoured to be his successor in the use of a rickety writing desk and a few aquaria in the Zoological Institute of the University of Vienna. Klaus was sort of a legend, having been to so many exotic places (e.g. he had participated in the International Indian Ocean Expedition in 1963). He often came to Croatia, where we younger PhD students were doing field work for our theses, and introduced us to Mediterranean marine life and the potent grappa of fishermen pubs in Rovinj.

Figure 1.

 Klaus Ruetzler in his laboratory at the Smithsonian Institution’s National Museum of Natural History, Washington, DC, with Sponge Bob (October 2006) (photo Robert W. Thacker).

After Klaus had moved to the US, where he became a citizen in 1973, we stayed in contact and infrequently met, for example during my post doc years in North Carolina, when Klaus would come to Morehead City to work with us and enjoy the then still cheap and abundant Blue Crabs. Later when I was teaching at the Bermuda Biological Station, Wolfgang Sterrer would be our amiable host, Arnfried Antonius would be there to study coral diseases, and Klaus collected sponges, making these weeks great reunions of Austrian marine scientists scattered in the four corners of the globe.

One of the topics we always discussed was the idea of a marine biology field station where one just needed to step out of the laboratory to find a diversity of habitats right at the front door. Our teacher Rupert Riedl had already pursued this dream, alas unsuccessfully. Wolfgang had become director of the BBS, but operating big ships (and a scientific hotel on the side) was not what we had in mind. When, after a coral reef workshop at Glover’s reef, Belize, Arnfried by chance discovered Carrie Bow Cay in 1972, Klaus tenaciously pursued the idea of establishing a research station there (Fig. 2). This laboratory had all the properties we had dreamed of; it was surrounded by coral reefs, mangrove forests and sea grass meadows, with a deep ocean at the front and secluded lagoons at the back, away from noisy tourism. It became a busy paradise for innumerable field researchers in marine biology, geology and palaeontology. This multidisciplinary environment soon made it one of the classical sites for marine research, where many disciplines work together to create a synthetic knowledge base of a region. Since then, researchers from more than 20 countries have visited Carrie Bow Cay and worked there with the support of the Smithsonian Institution’s Caribbean Coral Reef Ecosystem Program, which Klaus has led as director since 1985 (Rützler & Macintyre 1982; Rützler 2006). I was lucky to be one of them, and during my more than 20 visits I have experienced the lab as an excellent place for research and Klaus as a most generous host.

Figure 2.

 Klaus Ruetzler in front of the Belize barrier reef at Carrie Bow Cay (May 2007) (photo: Molly K. Ryan).

There are only few places where such a diverse selection of marine scientists has brought their expertise together. One such classic example is the Stazione Zoologica di Napoli. In 1980 Rupert Riedl together with Alberto Monroy, then President of the Stazione Zoologica, founded P.S.Z.N.: Marine Ecology as a modern version of the classic journal Pubblicazioni della Stazione Zoologica di Napoli. Klaus was among the first members of the Editorial Board. He continues to serve in that capacity, soliciting numerous publications, many of which originate from work done at the Carrie Bow Cay research station. Now, the journal in its new format, Marine Ecology – An Evolutionary Perspective, honors his continued involvement with a special volume dedicated to him and his beloved sponges.

The first time I, Maurizio, met Klaus was in the seventies when, on his way to Vienna to see his mother, he used to come to Italy to visit Professor Michele Sarà at the Zoology Institute of the University of Genova. This is where, as a fellowship student, I was learning about sponges from him and Gustavo Pulitzer-Finali.

The first investigations I, and my colleague Roberto Pronzato, performed during that period were related to sponges of the marine caves of the Gulf of Naples. Klaus’ papers on the ‘Sorrentiner Höhlen’, albeit written in German (Russ & Rützler 1959; Rützler 1966), were an extraordinary source of information. Klaus was also a member of the selected group of scientific divers, a fact that increased my admiration toward him and desire to follow in his footsteps.

In the following years we had the opportunities to meet more frequently, at the sponge symposium that he organized in Woods Hole, at his lab in Washington, DC, and in a series of workshops of sponge taxonomists, all designed for the purpose of producing an expert system for sponge classification.

I, Renata, have initiated an interest in sponges systematics and ecology more recently than Maurizio, but I also had the opportunity to participate in some of these meetings. Unfortunately we were not able to accomplish the expert system, notwithstanding our considerable faith in computer possibilities. However, we put together a new thesaurus of sponge terminology and began the design and construction of the Systema Porifera. But, more importantly, by organizing these meetings in our labs, we acquired among ourselves a growing familiarity, transforming our working relationships into a true and long lasting friendship.

In July 2001 both of us enjoyed a beautiful stay at Carrie Bow Cay, where we had the great opportunity to appreciate Klaus’ sensitivity in having chosen this unique location and the goals he and his team were able to accomplish through tenacious and long-lasting efforts.

When in 2006 our colleague and friend Maria Cristina Gambi proposed that we become guest editors for a special issue of Marine Ecology destined to honour Klaus, in conjunction with his retirement, we enthusiastically accepted. We sought to honour Klaus both for his many scientific achievements and his long service as Assistant Editor of this journal.

We wish to thank in primis all the authors for their contribution, and also the reviewers for their precious feedback. The editing work has been more complex than expected, but thanks to Lisa Levin’s and Maria Cristina’s experience as editors, and their relevant feedback on each contribution, difficulties were smoothly overcome.

This volume’s content covers a wide range of ecosystems and refers to some of the main research topics and key sponge models that Klaus investigated during his pioneering, exciting and fruitful research. Both veteran and young sponge researchers focused on basic research topics, from ecology and traditional natural history to new experimental approaches, to investigating neglected fields such as sponge physiology and behaviour.

An historical analysis by Pronzato and Manconi, based on a conservation biology perspective, stresses the need for new approaches to the management of sponges as natural resources. These authors also report on the various uses of commercial sponges by man and their non-rational fishery in the Mediterranean Sea, with special attention to their taxonomical status, distribution and possibilities of sustainable exploitation.

As to symbiosis, a comprehensive review deals with recent and past research on sponge-cyanobacteria associations, focusing on the necessity of a better understanding of their functional role in sponge survival and evolutionary success (Usher). Schönberg et al., on the other hand, highlight the sponge survival potential during climatic changes by comparing the photochemical efficiency of the symbiotic association of boring sponges with cyanobacteria versus reef building corals.

The relevance of sponge research to the whole scientific community, with special attention to the contribution of sponge ecology to the broader science of ecology, is evaluated by Becerro using productivity indicators. This paper highlights sponges as one of the main diversified and abundant components of benthic ecosystems.

Other papers evaluate diversity in shallow-water tropical assemblages at a synecological level. Carballo et al. present a long-term investigation taking into account both local and global climatic change trends in the environment. A short-term study by Wulff shows, in a study based at Carrie Bow Cay, how the collaborative behaviour of sponges as a defensive mechanism against predators can increase abundance and species diversity within a community. Voogd and Cleary report on the highly adverse effect that human alterations can have on proximate marine assemblages and sponge diversity.

As to autoecology, Kloppel et al. improve the knowledge of the behaviour of a photophilous, shallow water Mediterranean sponge in the controlled environmental conditions of a closed system, through the temporary screening of its morphology, metabolite production and microbial association. Some contributions provide new data on the morphology, taxonomy, geographic distribution and ecology of boring sponges, one of the many interests of Klaus (Rützler 1973, 1974, 2002; Rützler & Rieger 1973). They focus on a Mediterranean zooxanthellate clionaid strictly allied to tropical lineages (Vacelet et al.), and on a new Alectona species boring into red coral from the Pacific Ocean, with notes on the historical biogeography of the genus and the key role of widespread bio erosion (Calcinai et al.).

In the field of reproductive biology, Maldonado et al. and Uriz et al. show that morphological and cytological investigations are very important approaches to understanding the ecology of larvae and the role of their behaviour in determining both dispersal capacity and sponge distribution at topographic and geographic scales.

We hope the readers will enjoy the overview of sponge biology and ecology provided by these contributions, and that this volume offers a fitting tribute to Klaus for what he has done and continues to do for marine science and the sponge community.