Roberto Pronzato

Sponge-fishing, disease and farming in the Mediterranean Sea

1. Some Mediterranean sponge species belonging to the genera Spongia and Hippospongia, have been harvested for commercial purposes since ancient times. Recently, a widespread epidemic has greatly reduced the density of sponge populations which has had serious repercussions in the commercial field. 2. The synergetic action of harvesting and disease has taken a number of populations to the brink of extinction. Sponge-population densities are steadily decreasing and their recovery after the disease event is incomplete and has taken a long time. 3. There is a simple solution to the problem: sponge-farming. Trials have been underway since the beginning of the century and recently, Cuba, the Philippines and Micronesia Islands have started commercial sponge-farming. 4. Sponges are naturally able to remove dissolved organic matter, organic particles and bacteria from the water-column and this ability could be exploited in an integrated mariculture system. Floating cages for fish production result in the release of a lot of organic wastes that can be used as a source of food for surrounding intensive commercial sponge communities. Such an integrated system could result in effective eutrophication control, commercial sponge production and a consequent reduction of fishing effort on already heavily-stressed natural sponge populations. Copyright

Suborder Spongillina subord. nov.: Freshwater Sponges

Spongillina subord. nov. (Demospongiae, Haplosclerida) consists of seven families of exclusively freshwater sponges together containing 45 genera: Spongillidae (21 valid genera), Lubomirskiidae (three genera), Malawispongiidae fam. nov. (five genera), Metaniidae (five genera), Metschnikowiidae (monogeneric), Palaeospongillidae (monogeneric), Potamolepidae (six genera), some geographically widespread and others highly endemic. A central body cavity is peculiar to Malawispongiidae. Skeletal network is typically multispicular alveolate-reticulate with scanty spongin in Metaniidae, Potamolepidae and Malawispongiidae, paucispicular irregularly reticulate in Palaeospongillidae, Spongillidae, Metschnikowiidae with a variable amount of spongin, multi- to paucispicular irregularly reticulate with an abundant amount of spongin in Lubomirskiidae. Smooth or variably ornamented megascleres range from oxeas to strongyles in Spongillidae, Lubomirskiidae and Metaniidae, but are exclusively oxeas in Malawispongiidae, Metschnikowiidae, Palaeospongillidae, and exclusively strongyles in Potamolepidae. Microscleres usually present in Spongillidae, Palaeospongillidae and Metaniidae, are rare in Potamolepidae, and absent in Lubomirskiidae, Malawispongiidae and Metschnikowiidae. Microscleres if present are oxeas, strongyles, aster-like, pseudobirotules. Larvae are always parenchymella. Gemmules are typical of Spongillidae, Metaniidae, Palaeospongillidae, rare and strictly adhering to the substratum in Potamolepidae, and absent in Lubomirskiidae, Malawispongiidae and Metschnikowiidae. Gemmular theca is monolayered in Potamolepidae, mono-, bi- or tri-layered in Spongillidae, generally tri-layered in Metaniidae. Gemmules usually armed by gemmuloscleres in Metaniidae, Potamolepidae and Spongillidae, are rarely naked in the latter. Gemmuloscleres are boletiform (tubelliform), parmuliform, pseudobirotules in Metaniidae, and oxeas, strongyles, birotules, pseudobirotules, club-like, botryoidal in Spongillidae. Three more genera incertae sedis are included. This work is a relatively critical synthesis of the literature, however, a critical phylogenetic revision of established taxa is still in progress.

The marine sponge Chondrilla nucula Schmidt, 1862 as an elective candidate for bioremediation in integrated aquaculture.

The use of sponges for marine bioremediation in a farming scenario has been investigated focusing on Chondrilla nucula. We report experiments examining clearance and retention rates of the bacterium Escherichia coli. Despite low values expressed for clearance tests, C. nucula exhibited a marked ability to retain high quantities of bacteria. One square meter patch of this sponge can filter up to 14 l/h of sea water retaining up to 7 x 10(10) bacterial cells/h. This suggests that C. nucula is a suitable species for marine environmental bioremediation.

Life cycle of Spongilla lacustris (Porifera, Spongillidae): a cue for environment-dependent phenotype

We studied the life cycle and growth of Spongilla lacustris in a stream with three distinct habitats. Sponge populations in the habitats exhibited different adaptive strategies. Growth forms of S. lacustris ranged from encrusting to digitate and branched. Environmental factors controlled the appearance of each growth form. In the most hospitable habitat, a variety of colonization strategies and different growth forms were present. In the less hospitable habitat growth was restricted to small and encrusting specimens. In the optimal habitat, the largest and most luxuriant specimens developed. Gemmulation and hatching were dephased among specimens in the three habitats; hence gemmules were present for long periods of time. S. lacustris was found capable of displaying two life strategies: r in the short run, K in the long run.

BIORHYTHM AND ENVIRONMENTAL CONTROL IN THE LIFE HISTORY OF EPHYDATIA FLUVIATILIS (DEMOSPONGIAE, SPONGILLIDAE)

Abstract The life cycle of Ephydatia fluviatilis involves obligatory gemmule formation, a process strongly related to environmental conditions. A comparative investigation carried out on three populations of this species distributed along a climatic gradient, besides confirming a link between occurrence of gemmules and the severity of the habitat, evidences that gemmulation may be triggered even by endogenous stimuli. Indeed, in the northern area (Torrente Scrivia, Liguria), subjected to ice‐up and notable thermic and water‐flow fluctuations, the sponges hibernate for a long period and show shorter summer activity. In the southern area (Canale Tagliavla, Sicily), with a summer dry‐up, the active sponges are present during the winter, while the quiescence coincides with an aestivation. The persistence of this rhythm over the years is discussed, also in consideration of a speciation trend which points to a physiological reproductive barrier between these metapopulations. By contrast, in the intermediate are...

Rediscovery of the type material of Spongilla lacustris (L., 1759) in the Linnean herbarium

Abstract The type material of Spongilla lacustris, recently found in the Linnean herbarium, is described. Type locality and present distribution are shown. Morphological diagnostic traits are described by SEM microphotography. This is the single species of Porifera out of 12 described by Linnaeus in 1759, with type specimen known. A lectotype is selected from two syntypes.

Adaptive strategies of sponges in inland waters

Abstract The notable plasticity of Porifera allowed the colonization of inland waters during the Mesozoic Era as a consequence of the gradual morpho‐functional adaptations of dormant bodies, i.e., the appearance of the pneumatic coat and of spiny spicules, which could be responsible for the realization of an overland dispersal. The gem‐mule, with its high potentialities as an adaptive device, is the key structure in understanding the life history and the evolution of Spongillidae. The other two families of freshwater sponges, Potamolepidae and Lubomirskidae, do not have a widespread diffusion, probably because of the absence of specialized resistent bodies, such as gemmules, able to act as propagules. In spite of the ability to produce gemmules, few species of spongillids are cosmopolitan; Ephydatia fluviatilis shows the highest plasticity, adapting its life cycle to different climatic conditions: hibernant and aestivant populations live, respectively, in cold‐humid and warm‐arid climates. The persistent ...

The other side of rarity: recent habitat expansion and increased abundance of the horny sponge Ircinia retidermata (Demospongiae: Dictyoceratida) in the southeast Aegean

Abstract Environmental change is commonly considered as a driver for the extinction of rare species. This belief, long established on land, may not apply to marine species. Dramatic environmental change in the shallow marine ecosystems of Kos, an island in the Aegean (east Mediterranean Sea) caused algal reefs to shift to sponge reefs. Among the sponge species that gained supremacy on Kos reefs, the Mediterranean endemic Ircinia retidermata was previously a rare species. Comparing surveys carried out in 1981 and 2013 by the same method (time-based visual census along random paths by scuba diving), in the same sites, by the same people, showed that I. retidermata increased its overall abundance by one order of magnitude, and expanded its occurrence to all the habitats examined. This outcome contradicts the current common belief that rare species in semi-enclosed seas are prone to extinction. Besides being the state preceding final extinction, rarity could represent the source of variation that marine ecosystems need in order to face environmental change. However, for many marine invertebrates, and especially sponges, inferred rarity may simply be the result of insufficient investigation. This study represents an attempt to assess change with time in a rare sponge species’ abundance using visual census by scuba diving.

An overview of the Mediterranean cave-dwelling horny sponges (Porifera, Demospongiae)

Abstract The present synthesis focuses on the so called ‘horny sponges’ recorded from marine caves of the Mediterranean Sea. The main aim is to provide a list of all recorded species, diagnostic keys to their identification up to family and genus level, and exhaustive, formally uniform descriptions at the species level contributing to sharing of information on the faunistics and taxonomy of Mediterranean cave-dwelling species, including habitat preferences. The majority of species was recorded in 105 Mediterranean marine caves hosting four orders of horny sponges belonging to 9 families, 19 genera and 40 species. Species endemic to the Mediterranean Sea harboured in marine caves are 14 with an endemicity value of 35%. For each species morphological descriptions are supported by illustrations both original and from the literature, including the diagnostic traits of the skeleton by light and scanning electron microscopy giving further characterization at the specific level. A detailed map together with a list of all caves harbouring horny sponges is also provided with geographic coordinates.

Long-term turnover of the sponge fauna in Faro Lake (North-East Sicily, Mediterranean Sea)

Abstract The paper focuses on the long-term taxonomic composition and distribution of the shallow-water sponge fauna from the meromictic–anchialine coastal basin Faro Lake (Southern Italy), comparing recent qualitative field data with literature data over a 50-year period. The Faro Lake shallow water currently hosts 24 conspicuous species of Porifera belonging to 21 genera, 18 families, eight orders, three subclasses and two classes, i.e. Demospongiae (23) and Calcarea (one). The comparison between the present and past status of the sponge fauna showed a high turnover, with 15 new colonizers and only nine persistent species. Thirteen species reported in the literature are missing, suggesting the occurrence of remarkable changes in the faunal composition during the last 50 years. The analysis of the geographic distribution of each species allowed us to outline the prevalent North Atlantic affinity of the sponge community. Worthy of note is the new record of the alien calcareous sponge Paraleucilla magna of cryptogenic origin.