Although still very scarce, available knowledge on population studies on continental (land and freshwater)molluscs in the territory of Santa Catarina State is shortly analyzed and discussed. Based on the IUCN“Restricted Distribution” criterion, a total of 54 nominal species, including 31 terrestrial gastropods, 15freshwater gastropods and 8 limnic bivalves, were considered strong candidates as threatened taxa. Out of allthese endangered species, only 5 limnic forms (2 gastropods and 3 bivalves) were previously analysed, in someway, at population level

A. Ignacio Agudo-Padrón

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INTRODUCTIONAs already reported in Moraes (2006), allBrazilian autochthonous continental molluscspecies are seriously threatened with extinction.Moreover, there are presumably a high numberof taxa still awaiting discovery and numerousothers that, as a first step for their conservation,need to be investigated and inventoried withalacricity. Considering the rapid rate of currentanthropic environmental degradation, severalspecies will surely become extinct before thescientific community gets to know them all(Simone, 2006).Besides the environmental degradation(including deforestation for agricultural aims orforest exploitation, mining, pollution of the riverbasins with dejections and several pollutants,indiscriminate use of agricultural poisons andchemical fertilizers, proliferation of theconstruction of hydroelectric mills, invasions ofnatural spaces by town planning enterprises), theBrazilian species face considerable competitionwith invading forms that, among others, are alsoresponsible for serious sanitary and agronomicproblems (Agudo & Bleicker, 2006a; Agudo-Padrón, 2008; Agudo-Padrón & Lenhard, 2010).Introduced willfully or accidentally, allochthonousinvading species are novel to local ecosystemsand, for this reason, lack any natural predators,thus achieving an uncontrolled growth ofpopulations with, consequently, extinction ofnative species and an indiscriminate occupationof native (often under-exploited) niches.Taking into account that molluscs found inrivers and lakes show extinction rates rangingfrom four to six times higher than theircounterparts in marine or terrestrial habitats,these species are the most threatened globallydue to the widespread collapse of such fluvialecosystems. In particular, freshwater bivalves arevery sensitive to trampling, organic and chemicalpollution and other different types ofenvironment degradation. Moreover, they show arelatively slow growth rate and don’t usually re-settle in previously abandoned/discarded areas.There a few endemic species for each basin andmany of them inhabit restricted and seriouslyCurrent knowledge on population studies on five continental molluscs(Mollusca, Gastropoda et Bivalvia) of Santa Catarina State (SC, CentralSouthern Brazil region)A. Ignacio Agudo-PadrónProject “Avulsos Malacológicos - AM”, P.O. Box 010 - 88010-970, Florianópolis, Santa Catarina, SC, Brasil; ignacioagudo@gmail.com;http://noticias-malacologicas-am.webnode.pt Biodiversity Journal, 2011, 2 (1): 9-12ABSTRACT Although still very scarce, available knowledge on population studies on continental (land and freshwater)molluscs in the territory of Santa Catarina State is shortly analyzed and discussed. Based on the IUCN“Restricted Distribution” criterion, a total of 54 nominal species, including 31 terrestrial gastropods, 15freshwater gastropods and 8 limnic bivalves, were considered strong candidates as threatened taxa. Out of allthese endangered species, only 5 limnic forms (2 gastropods and 3 bivalves) were previously analysed, in someway, at population level.KEY WORDS Biodiversity, Conservation status, Continental mollusc populations, Santa Catarina State, Southern Brazil region.Received 08.01.2011; accepted 13.02.2011; printed 30.03.2011threatened areas suffering from countlessenvironment alterations recently elicited byhuman activities. This scenario worsened still bythe absence of these species from “red lists”provided by ecology centers or units. Nearlynobody wants to preserve a natural area justbecause of a snail; unfortunately, molluscs,although being fundamental for ecologicalbalance (Moraes, 2006), have a very smallerappeal when compared to any vertebrate speciesand are considered as non-charismatic species.In the present work, current knowledge onnative continental molluscs of Santa Catarina Stateis reported by publishing information availablefrom past population studies. As far as availabledata on autochthonous malacofauna in SantaCatarina State is concerned, reference should bemade to Agudo-Padron (2011). As alreadyunderlined in the above mentioned paper,continental forms are currently sub-appraised dueto a sensitive lack of population studies coupledwith a traditional and historical chronic lack, in theState, of specialists working on continental forms.In this paper, 54 continental native species - 46Gastropoda (31 land and 15 freshwater taxa) and 8limnic Bivalvia (Agudo-Padrón, 2010), along withtwo recent new registrations for the Extreme Westernarea of the State, Macrodontes thielei Pilsbry, 1930(Odontostomidae) and Streptaxis pfeifferi (Pilsbry,1930) (Streptaxidae) (Agudo-Padrón & Bleicker,2011), were considered for inclusion in IUCNcategories of specific status of threat andconservation, based on the specific RestrictedDistribution Criterion. Out of these taxa only thefollowing five species have been studied, somehow,at population level in Santa Catarina State:Class GASTROPODAProsobranchia/CaenogastropodaFamily AMPULLARIIDAE Gray, 1824Genus Pomacea Perry, 1811Pomacea lineata (Spix, 1827)Available preliminary population studieswere reported a few years ago (Santos et al.,2005; Quadros et al., 2007). This taxon wasincluded in the specific IUCN categoryENDANGERED (EN).Pomacea lineata (Spix, 1827), also known asapple snail, is a native taxon the rank of which isstill contentious. In fact, it was considered byseveral authors an essential element of thecanaliculata  complex, but, on the other hand,recognized as a valid species by local specialists(Thiengo, 1987; Cowie & Thiengo, 2003;Simone, 2006). In our opinion, this is a sterilediscussion, since, whatever its taxonomic rankmight be, we really need to evaluate theconservation status of this taxon in the State,since it inahibits a restricted area (Salto do RioCaveiras, Santa Catarina plateau) under strongregional thread from hydroelectric development(Santos et al., 2005; Agudo-Padrón, 2008, 2010).Family HYDROBIIDAE Stimpson, 1865Genus Potamolithus Pilsbry, 1896Potamolithus kusteri (Ihering, 1893)For preliminary population studies see Santoset al. (2005) and Quadros et al. (2007). Thistaxon was included in the specific IUCNcategory VULNERABLE (VU).It occurs in a restricted area (Salto do RioCaveiras, Santa Catarina plateau) under strongregional thread from hydroelectric development(Santos et al., 2005; Agudo-Padrón, 2008, 2010).Class BIVALVIAUNIONOIDA (freshwater mussels/naiads)Family HYRIIDAE Swainson, 1840Genus Diplodon, Spix, 1827Diplodon parallelipipedon (Lea, 1834) Preliminary population studies were previouslyreported (Santos et al., 2005; Quadros et al.,2007). This taxon was included in the specificIUCN category ENDANGERED (EN). It occursin a restricted area (Salto do Rio Caveiras, SantaCatarina plateau) under strong regional threadfrom hydroelectric development (Santos et al.,2005; Agudo-Padrón, 2008, 2010).VENEROIDA (freshwater clams)Family SPHAERIIDAE Deshayes, 1854Genus Pisidium Pfeiffer, 1821Pisidium pipoense (Ituarte, 2000)Preliminary population studies were carriedout by Perizzolo (2003) and Agudo-Padrón(2008, 2010). This taxon was included in the10 A. IGNACIO AGUDO-PADRÓNspecific IUCN category ENDANGERED (EN).It occurs in a restricted area (Lageado São José,Chapecó municipal district, Uruguay Rivervalley) under severe human influence (waterreservoir).Pisidium taraguyense (Ituarte, 2000)Preliminary population studies were carriedout by Perizzolo (2003) and Agudo-Padrón(2008, 2010). This taxon was included in thespecific IUCN category ENDANGERED (EN).It occurs in a restricted area (Lageado SãoJosé, Chapecó municipal district, Uruguay Rivervalley) under severe human influence (waterreservoir).DISCUSSION AND CONCLUSIONSOut of 54 continental species, only 5 limnicforms (2 gastropods and 3 bivalves) have beenpreliminarily studied at population level, withnone of these studies ever being formallypublished. Hence, at present, in spite ofburgeoning scientific and technological progress,we still have a lot of difficulty in evaluatingthreats menacing continental mollusc specieswithin the territory of Santa Catarina State, SC,the smallest portion of the Southern Brazilmosaic (Agudo & Bleicker, 2006b; Agudo,2007). The main reasons for this are, amongothers, the lack of concrete population data andthe extremely small amount of taxonomicspecialists on these species living and working inthe State.Personally, during 14 years of work in thefield, the author has witnessed the decrease andeven the extirpation of certain species fromseveral places and specific areas of the SC State.One example is the native giant snailMegalobulimus gummatus (Hidalgo, 1870), amagnificent representative of the familyMegalobulimidae in the valley of the Uruguayriver basin which was abundant  until a few yearsago; currently this species is difficult to locate insuch an area, probably due to the consequencesof the increase of regional agricultural activities(use of pesticides, mainly). Meanwhile, invadingexotic species proliferate and colonize largerareas.Endemic species, such as the small aquaticsnail  Potamolithus catharinae Pilsbry, 1911,representative of the family Hydrobiidae, and thetiny freshwater limpets Burnupia ingae Lanzer,1991 and Ferrissia gentilis Lanzer, 1991, familyAncylidae (Agudo-Padrón, 2008), are particularlyvulnerable since their fragile natural habitat iseasily altered by a multitude of human activities.In general, for Brazilian fluvial habitats thereis a regrettable lack of basic conservation andmanagement information, particularly dealingwith the spatio-temporal dynamics ofpopulations and communities, as well as with theimpact of several human activities. Hence, forthis reason, it is extremely important to pay greatattention to the conservation status of continentalmolluscs, including those occurring in SantaCatarina State.ACKNOWLEDGEMENTSVery thanks to Dra. Roberta Aguiar dosSantos, Official researcher of the CEPSUL –ICMBio (Itajaí, SC), for critical observations,suggestions and useful information.REFERENCESAgudo A.I., 2007. Continental land and freshwater molluscsin Santa Catarina State, Southern Brasil: a generalreview of current knowledge. Tentacle, 15: 11-14.Available online at: http://www.hawaii.edu/cowielab/tentacle/tentacle_15.pdf.Agudo-Padrón A.I., 2008. Listagem sistemática dosmoluscos continentais ocorrentes no Estado de SantaCatarina, Brasil. Comunicaciones de la SociedadMalacológica del Uruguay, 9: 147-179. Available onlineat: http://redalyc.uaemex.mx/redalyc/pdf/524/52412049003.pdf.Agudo-Padrón, A.I., 2010. The mollusc fauna of SantaCatarina State, Southern Brasil: knowledge gained from13 years of research. Tentacle, 18: 32-37. Availableonline at: http://www.hawaii.edu/cowielab/tentacle/Tentacle_18.pdf.Agudo-Padrón, A.I., 2011. Mollusca and environmentalconservation in Santa Catarina State (SC, SouthernBrazil) : current situation. Biodiversity Journal, 2 (1):3-8.Agudo A.I. & Bleicker M.S., 2006a. Moluscos exóticos noEstado de Santa Catarina. Informativo SBMa, Rio deJaneiro, 37: 6-8.11 Current knowledge on population studies on five continental molluscs of Santa Catarina State (SC, Central Southern Brazil region)Agudo A.I. & Bleicker M.S., 2006b. First generalinventory of the malacological fauna of Santa CatarinaState, Southern Brasil. Tentacle, 14: 8-10. Availableonline at: http://www.hawaii.edu/cowielab/tentacle/tentacle_14.pdf.Agudo-Padrón, A.I. & Bleicker, M.S. 2011. Additional newrecords on recent marine and continental molluscs ofSanta Catarina State, SC, Southern Brazil region:synthesis and check list. Ellipsaria. 13: 20-26.Agudo-Padrón A.I. & Lenhard P., 2010. Introduced andinvasive exotic molluscs in Brazil: an brief overview.Tentacle, 18: 37-41. Available online at: http://www.hawaii.edu/cowielab/tentacle/Tentacle_18.pdf.Cowie R.H. & Thiengo, S.C., 2003. The apple snails of theAmericas (Mollusca: Gastropoda: Ampullariidae:Asolene, Felipponea, Marisa, Pomacea, Pomella): anomenclatural and type catalog. Malacologia, 45: 41-100.Moraes M.S., 2006. O manual dos moluscos do Brasil. SãoPaulo, SP: Jornal da USP, 22: 7.Perizzolo R., 2003. Distribuição longitudinal de Mollusca(Bivalvia) no rio Lajeado São José, Chapecó - SC.Chapecó, SC: UNOCHAPECÓ, Dissertação Bacharelem Ciências Biológicas, 25 pp.Quadros R.M., Gambá G.A., Santos D.B., Peruzzolo G.,Lima L.C. & Marques S.M.T., 2007. A ecologia damalacofauna dulcícola do alagado do Salto do rioCaveiras na serra catarinense, Brasil. Rio de Janeiro, RJ:Resumos XX Encontro Brasileiro de Malacologia: 304.Santos D.B. Dos, Peruzzolo G. & Gambá G.A., 2005. Olevantamento e a ecologia da malacofauna dulcícola doAlagado do Salto do Rio Caveiras na Serra Catarinense.Lages, SC: UNIPLAC, Relatório de Estágio(Licenciatura Plena em Ciências Biológicas), 157 pp.Simone L.R.L., 2006. Land and freshwater molluscs ofBrazil. São Paulo, SP: FAPESP, 390 pp.Thiengo S. C., 1987. Observations on the morphology ofPomacea lineata (Spix, 1827) (Mollusca, Ampullariidae).Memórias do Instituto Oswaldo Cruz, 82: 563-570.12 A. IGNACIO AGUDO-PADRÓN

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Current knowledge on population studies on five continental molluscs (Mollusca, Gastropoda et Bivalvia) of Santa Catarina State (SC, Central Southern Brazil region)

Current knowledge on population studies on five continental molluscs (Mollusca, Gastropoda et Bivalvia) of Santa Catarina State (SC, Central Southern Brazil region)

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