Pea Clams Research Articles

Responses of Freshwater Calcifiers to Carbon-Dioxide-Induced Acidification

Increased anthropogenic carbon dioxide (CO2) in the atmosphere can enter surface waters and depress pH. In marine systems, this phenomenon, termed ocean acidification (OA), can modify a variety of physiological, ecological, and chemical processes. Shell-forming organisms are particularly sensitive to this chemical shift, though responses vary amongst taxa. Although analogous chemical changes occur in freshwater systems via absorption of CO2 into lakes, rivers, and streams, effects on freshwater calcifiers have received far less attention, despite the ecological importance of these organisms to freshwater systems. We exposed four common and widespread species of freshwater calcifiers to a range of pCO2 conditions to determine how CO2-induced reductions in freshwater pH impact calcium carbonate shell formation. We incubated the signal crayfish, Pacifastacus leniusculus, the Asian clam, Corbicula fluminea, the montane pea clam, Pisidium sp., and the eastern pearlshell mussel, Margaritifera margaritifera, under low pCO2 conditions (pCO2 = 616 ± 151 µatm; pH = 7.91 ± 0.11), under moderately elevated pCO2 conditions (pCO2 = 1026 ± 239 uatm; pH = 7.67 ± 0.10), and under extremely elevated pCO2 conditions (pCO2 = 2380 ± 693 uatm; pH = 7.32 ± 0.12). Three of these species exhibited a negative linear response to increasing pCO2 (decreasing pH), while the fourth, the pea clam, exhibited a parabolic response. Additional experiments revealed that feeding rates of the crayfish decreased under the highest pCO2 treatment, potentially contributing to or driving the negative calcification response of the crayfish to elevated pCO2 by depriving them of energy needed for biocalcification. These results highlight the potential for freshwater taxa to be deleteriously impacted by increased atmospheric pCO2, the variable nature of these responses, and the need for further study of this process in freshwater systems.

Biological Early Warning Systems: The Experience in the Gran Sasso-Sirente Aquifer

Biological early warning systems (BEWS) are installed worldwide for the continuous control of water intended for multiple uses. Sentinel aquatic organisms can alert us to contaminant presence through their physiological or behavioural alterations. The present study is aimed at sharing the experience acquired with water biomonitoring of the Gran Sasso-Sirente (GS-S) aquifer. It represents the major source of the Abruzzi region surface water, also intended as drinkable and for irrigation use. Besides the biomonitoring of drinkable water of the Teramo Province made by Daphnia Toximeter and irrigation water of the L’Aquila Province by Algae Toximeter, a novel sensor named “SmartShell” has been developed to register the behaviour of the “pea clam” P. casertanum, an autochthonous small bivalve living in the Nature 2000 site “Tirino River spring”. The valve movements have been recorded directly on the field. Its behavioural rhythms have been analysed through spectral analyses, providing the basis for further investigations on their alterations as early warnings and allowing us to propose this autochthonous bivalve species as a novel sentinel organism for spring water.

Intraspecific Variation in the Common Pea Clam, Pisidium casertanum (Poli, 1791) (Bivalvia: Sphaeriidae): A Geometric Morphometric Analysis

The morphological plasticity of bivalve species may impair their correct identification. Pisidium species (Sphaeriidae) are difficult to distinguish, notably the common pea clam, Pisidium casertanum (Poli, 1791), which is a polymorphic species, often misidentified and confused with other Pisidium species. This is especially true since this species is the most euryecious of the genus, being able to colonize very different habitats. In this study, elliptic Fourier Analysis, a geometric morphometric method, was used to assess intraspecific variation in P. casertanum. Sampling of specimens was done in three habitat types – springs, lakes and streams – in the Mediterranean biodiversity hotspot region, using the Sebou basin in Morocco as a study area. In addition to the geometric morphometric method, linear measurements of the shell were used to assess growth patterns. Results revealed differences in the hinge plate, which is broader in shells collected from lakes, whereas it is higher in shells of springs. The geometric morphometric method clearly showed shape differences between individuals of the three habitats. Specimens of lakes were the most distinguishable, presenting more elongated shells than those from springs and streams, which are shorter but higher. Individuals from the three habitat types presented a negative allometric growth pattern whereby the shell of animals grows more slowly in height than in length. The use of linear and geometric morphometric methods led to conclude that the morphology of P. casertanum is, in fact, highly influenced by its environment, in particular, its habitat type.

Reproductive features of Pisidium casertanum (Poli, 1791) (Bivalvia: Sphaeriidae) in relict lakes of Bolshezemelskaya Tundra

The reproductive features of the pea clam Pisidium casertanum in relict lakes of Bolshezemelskaya Tundra were studied. The P. casertanum population in the Vashutkiny Lakes of Bolshezemelskaya Tundra has a single period of summer reproduction. We suppose that the release of embryos mainly occurs between July and August and the breeding season could probably begin in May-June. The positive relationship between brood size and parent shell length was detected. We did not find a specific brooding mechanism, accompanied by asynchronous development and release of embryos by the parent in the population of P. casertanum in the Vashutkiny Lakes. The reason for this is probably related with the environmentally more stable freshwater habitats of the relict Vashutkiny Lakes in comparison with the lakes of the High Arctic.

Elucidating the Behavior of Cyclic Volatile Methylsiloxanes in a Subarctic Freshwater Food Web: A Modeled and Measured Approach

Cyclic volatile methylsiloxanes (cVMS) are used in personal care products and emitted to aquatic environments through wastewater effluents, and their bioaccumulation potential is debated. Here, a new bentho-pelagic version of the ACC-HUMAN model was evaluated for polychlorinated biphenyls (PCBs) and applied to cVMS in combination with measurements to explore their bioaccumulation behavior in a subarctic lake. Predictions agreed better with measured PCB concentrations in Arctic char (Salvelinus alpinus) and brown trout (Salmo trutta) when the benthic link was included than in the pelagic-only model. Measured concentrations of decamethylcyclopentasiloxane (D5) were 60 ± 1.2 (Chironomidae larvae), 107 ± 4.5 (pea clams Pisidium sp.), 131 ± 105 (three-spined sticklebacks: Gasterosteus aculeatus), 41 ± 38 (char), and 9.9 ± 5.9 (trout) ng g-1 wet weight. Concentrations were lower for octamethylcyclotetrasiloxane (D4) and dodecamethylcyclohexasiloxane (D6), and none of the cVMS displayed trophic magnification. Predicted cVMS concentrations were lower than measured in benthos, but agreed well with measurements in fish. cVMS removal through ventilation was an important predicted loss mechanism for the benthic-feeding fish. Predictions were highly sensitive to the partition coefficient between organic carbon and water (KOC) and its temperature dependence, as this controlled bioavailability for benthos (the main source of cVMS for fish).

Zoology: Molluscs All Beneath the Sun, One Shell, Two Shells, More, or None

One great remaining problem in evolutionary biology is to understand which common ancestor could have given rise to descendants as different as giant squid and microscopic pea clams. Two new papers provide important insights into molluscan body plan disparity.

Taxonomic status of <i>Pisidium amnicum </i>(Müller, 1774) and <i>P. inflatum</i> Megerle von Mühlfeld in Porro, 1838 (Mollusca: Bivalvia: Sphaeriidae)

In accordance with the taxonomic system adopted in Russia and used also in Estonia, the largest local forms of pea clams (Sphaeriidae) have been treated as two species, P. amnicum and P. inflatum . The aim of the study was to clarify if P. amnicum and P. inflatum are separate species. Populations of both forms from Estonia were analysed genetically and morphologically. Analysis of the COI and ITS-1 gene fragments revealed that these two forms were genetically indistinguishable. Although there were statistically significant differences in the relative proportions of the shell between their typical individuals, there occurred also intermediate values. Consequently, P. inflatum cannot be considered as a separate species and should be treated as an ecological variety of P. amnicum that inhabits mainly a characteristic sandy substrate.

Variability in the functional role of Arctic charr Salvelinus alpinus as it relates to lake ecosystem characteristics

This study investigated how dietary habits vary with lake characteristics in a fish species that exhibits extensive morphological and ecological variability, the Arctic charr Salvelinus alpinus. Iceland is a hotspot of geological activity, so its freshwater ecosystems vary greatly in physical and chemical attributes. Associations of dietary items within guts of charr were used to form prey categories that reflect habitat-specific feeding behavior. Six prey categories were defined and dominated by snails (Radix peregra), fish (Gasterosteus aculeatus), tadpole shrimp (Lepidurus arcticus), chironomid pupae, pea clam (Pisidium spp.), and the cladoceran Bosmina sp.. These reflected different combinations of feeding in littoral stone, offshore benthic, and limnetic habitats. Certain habitat-specific feeding strategies consistently occurred alongside each other within lakes. For example, zooplanktivory occurred in the same lakes as consumption from offshore habitats; piscivory occurred in the same lakes as consumption from littoral benthic habitats. Redundancy analyses (RDA) were used to investigate how lake environment was related to consumption of different prey categories. The RDA indicated that piscivory exhibited by Arctic charr was reduced where brown trout were abundant and lakes were shallow, greater zooplanktivory occurred at lower latitudes and under decreased nutrient but higher silicon dioxide concentrations, and benthic resource consumption was associated with shallower lakes and higher altitudes. This study showed that trends previously observed across fish species were supported at the intraspecific level, indicating that a single species with flexible dietary habits can fill functional roles expected of multiple species in more diverse food webs.

The rheophilic fauna and invertebrate communities of the tundra zone: A case study of the Southern Yamal

The invertebrate fauna of rivers and streams of the Southern Yamal has been studied using original specimens (122 bottom and vegetation samples). A total of 158 taxa have been recorded, many of which are new for this region. Among them, 18 types of rheophilic macrobenthic communities have been distinguished which mainly correspond to certain types of habitats and watercourses. A depletion in the set of rheophilic communities (including the loss of almost all crenal and many phytal ones), the taxonomic structure of communities (the loss of large bivalves and most gastropods, hemipterans, and dragonflies), and the total species composition of the fauna, as well as changes in the balance of life forms towards filter feeders (larvae of the family Simuliidae midges and pea clams) and leveling of the differences between the communities of large and small watercourses when compared with the communities of the Russian forest zone, have been recorded. Widespread Eurosiberian species are the most abundant in the rheophilic fauna of the examined region, Arctic species account for ∼20% of all species, and six East Siberian species have been found. No endemic species have been discovered.

The occurrence of Pisidium species (Bivalvia: Sphaeriidae) in oligotrophic springs of the Blanice River catchment (Czech Republic) in relation to ecological conditions

This paper presents a part of the results obtained from extensive studies conducted on springs — remarkable freshwater habitats with many unique characteristics and a high degree of biological diversity. The abiotic conditions and fauna composition of 68 submontane permanent oligotrophic springs in the Blanice River catchment (eastern part of The Bohemian Forest, Czech Republic) were investigated with a focus on their relationship to the Pisidium species occurrence. We attempted to determine the habitat requirements of individual pea clam species. Species of genus Pisidium generally preferred unshaded springs with fine substrate, the most favourable environment were helocrene springs. Although they were the second most numerous taxonomical group in the springs, only two species were present there: Pisidium casertanum and P. personatum. The occurrence of both species strongly positively correlated with each other. Substrate type and a few chemical parameters were the main parameters, which differentiated the distribution of both species. While P. casertanum was found to be most abundant in vegetation, P. personatum preferred humolite substrate. The occurrence of P. casertanum was further influenced by nutrients compared to P. personatum, whose occurrence positively correlated with the common minerals. In general, biotope characteristics of springs were found to be more important for Pisidium species inhabiting oligotrophic mountain springs than water chemistry.

Freshwater Mollusks Survive Fish Gut Passage

Freshwater mollusks figure prominently in the diets of humpback whitefish (Coregonus pidschian) and broad whitefish (C. nasus), two benthic-feeding coregonid species. A recent examination of pea clams (Sphaeriidae), valve snails (Valvatidae), and pond snails (Lymnaeidae) from the lower digestive tracts of these fish found that many of the mollusks were alive. Survival completely through gut passage would indicate a dispersal mechanism for freshwater mollusks that has not been previously recognized. A field investigation was conducted with wild-caught humpback and broad whitefish to test the hypothesis that clams and snails are capable of surviving complete gut passage. Wild fish were captured alive and held in collection totes to obtain feces samples. Pea clams and valve snails were abundant in fish feces, and pond snails were present but not abundant. An average of 483 pea clams and 833 valve snails per fish were observed to have survived complete gut passage, while only a single surviving pond snail was found. These findings suggest that fish may play an important role in the dispersal of freshwater mollusks within freshwater systems.

The neglected side of speciation in ancient lakes: phylogeography of an inconspicuous mollusc taxon in lakes Ohrid and Prespa

The morphologically remarkable endemic fauna within ancient lakes has received much attention in the literature. More inconspicuous taxa, however, often lack detailed molecular and morphometrical examination, although their proportion of the endemic fauna of an ancient lake must not be underestimated. Consequently, a better understanding of evolutionary patterns and processes within these lakes requires more knowledge about the often-neglected inconspicuous taxa. In the present study, we focus on the notoriously cryptic pea clam genus Pisidium (Bivalvia: Sphaeriidae). Though the genus is widely distributed, most endemic species are reported only from ancient lakes, including the European ancient sister lake system of Ohrid and Prespa on the Balkan Peninsula. Here we test for the first time hypotheses on the evolution of the endemic pea clams in this European biodiversity hotspot by molecular means. Combining a broad 16S phylogeny (comprising most European pea clam species), network analyses and morphometrical analyses, we found interesting biogeographical patterns and provide evidence for cryptic species in both lakes. Furthermore, we confirmed the proposed sister-species relationship of the endemics P. edlaueri in Lake Ohrid and P. maasseni in Lake Prespa, and we suggest scenarios of the endemic pea clam evolution within both lakes. The patterns of speciation found in the genus Pisidium are compared to patterns in morphologically distinct molluscan groups in lakes Ohrid und Prespa.

Spatio-temporal pattern of mussels (Corbiculidae, Dreissenidae, Sphaeriidae) in the water-system of the Hungarian Danube

In 1998 and 2001 collections were carried out at 83 sampling sites in different water bodies of the Hungarian Danube section. In the period of 1996-2003 during the hydrobiological monitoring of the Szigetkoz area 15 sites, which are affected especially by the hydrological changes due to the diversion of the Danube, were studied. Regarding the sampling sites altogether, 16 small-sized mussel species of 3 families were found, which presents 73 % of the nation-wide fauna. Among them two species (Corhicula fluminea, Dreissena polymorpha polymorpha) are invasive mussels and four (Pisidium amnicum, Pisidium milium, Sphaerium rivicola, Sphaerium solidum) are rare species in Hungary. The radical alteration in the hydro-morphology of the Szigetkoz area caused by the diversion of the Danube to the operation channel of Bos/Gabcikovo hydroelectric power plant was followed by the impoverishment of the mussel fauna. The composition of mussel fauna had been considerably changed between 1996 and 2003. In the period before 2000 the small-sized mussel fauna contained 11 species, but in the period after 2000 the fauna increased with 2 fingernail clams (Sphaerium rivicola, Sphaerium solidum) and one pea clam (Pisidium casertanum var. ponderosum). Beside the increase in the number of species a process to uniformity could be detected, since the ratio of species occurring only in one water body gradually decreased. The number of species occurring in more than one water body increased until the beginning of 2000. The previous flood prevention classification of the Szigetkoz area could be found less and less typical in the spatial pattern of the mussel fauna. In the last years of the investigated period the water regime of the active alluvial floodplain followed the natural water fluctuation of the Danube. The water dynamics of the active alluvial floodplain differs both from the abandoned main channel and the protected area due to the changed mode of water supply. The decrease of similarity between the water bodies could represent a tendency towards the situation before altering the hydrological exchange conditions in the wetland.

Annotated catalogue of type specimens of Sphaeriidae (Bivalvia, Heterodonta, Veneroida) in the Mollusc collection of the Museum für Naturkunde Berlin, with a review of their current taxonomic status

The Sphaeriidae, i.e. fingernail, pea or pill clams, comprise the smallest freshwater bivalves as adequately indicated by their naming. The systematics and phylogeny of the family is currently under revision. In connection with this ongoing work published elsewhere we here present an alphabetical catalogue comprising the types of 46 sphaeriid species, subspecies and varieties in the Malacological collection of the Natural History Museum Berlin, each listed by its original and most used current binomina. Several types not known to previous reviewers, e.g. syntypes of Cyclas capense Krauss, 1848 and of two Baikalian species, were found and included. Lectotypes of 9 species are designated herein (including 3 lectotypes selected earlier by Kuiper but not published). Modern views on taxonomy of all species and forms are briefly commented on. The status of the following taxa is changed: Sphaerium asiaticum (v. Martens 1864) is treated as a valid species. Pisidium obtusale var. magnificum Clessin in Westerlund, 1873 is synonymised with P. globulare auct. which is also treated as a distinct species. We suggest that S. naivashaense Preston, 1912 and S. mutandaensis Preston in Dautzenberg & Germain, 1914 are synonyms of S. capense (Krauss 1848) and confirm the synonymy of P. maculatum (Dybowski, 1902) with Lacustrina dilatata (Westerlund. 1897).

Anatomy and reproduction of viviparous Pisidium ( Parapisidium) reticulatum Kuiper, 1966: Implications for the phylogeny of Sphaeriidae (Mollusca: Bivalvia: Heterodonta)

The pea clams Sphaeriidae represent a major molluscan freshwater radiation with cosmopolitan distribution in all kinds of lotic and lentic habitats. Their phylogenetic relationships are still controversial, with comprehensive taxonomic sampling and examination of morphological characters still challenging. Here, based on rare and rediscovered original material, we study in detail the anatomy and aspects of brood protection of the African Pisidium reticulatum Kuiper, 1966. Representing the monotypic subgenus Parapisidium Kuiper, 1966, this species is characterized by its peculiar combination of shell and anatomical features of potentially high phylogenetic relevance. While similar to other congeners in several anatomical characters (e.g. reduction of inhalant siphon and descending lamella of outer demibranch, simplified structure of intestine coil and nephridium), P. reticulatum differs from other Pisidium species in retaining both pairs of retractor muscles of the inhalant siphon, and particularly in its peculiar mode of brooding. The yolky eggs are relatively large (160–170 μm in diameter) and are incubated in the gill, albeit in the absence of the formation of brood pouches. During later stages of incubation the larvae are surrounded by large cells similar to nourishing cells in other sphaeriids and probably with similar function. This unique combination of reproductive features is hypothesized to represent an intermediate stage between the typical ovoviviparity of Euperidae and euviviparity (i.e. nourishment by the parent animal) as found exclusively in Sphaeriidae, the latter being characterized by the possession of closed brood pouches. Phylogenetic analyses based on a comprehensive set of morphological characters reveal Parapisidium as the most basal lineage within a clade Pisidium. Evaluating the phylogenetic reconstructions based also on available molecular data for Sphaeriidae, we discuss alternative scenaria of (parallel) evolution of brood pouches and viviparity in this group.

LIFE-HISTORY PATTERNS IN THE BROODING FRESHWATER BIVALVE PISIDIUM (SPHAERIIDAE)

Of all freshwater molluscs, the life history of sphaeriid bivalves has been one of the best studied, partly because they brood their young. In Pisidium, one of five genera in the Sphaeriidae, offspring develop and are released synchronously and therefore the reproductive state is easily determined from collections of adults. This study examines life-history trade-offs, morphological constraints on reproductive effort, intraclutch variation and brood production differences in different habitats in the pea clam, Pisidium. My results challenge previous ideas about life-history trade-offs in the pea clams and are as follows: (1) there is a trade-off between offspring number and size, larger embryos being found in smaller clutches when controlling for adult body size; (2) total embryo area is highly correlated with total gill area, but the measured maximum total area of embryos relative to gill area is rarely achieved; (3) intraclutch variance itself varies non-normally across Pisidium and does not appear to relate strongly to other measured variables; (4) creeks, ponds, springs and marshes appear to have higher relative per-clutch brood production than lakes in the best-sampled taxon, P. casertanum. Relative brood production is lower in high alpine lakes (above 3350 m), perhaps due to low dissolved organic material and ions.

Moitessier's pea clam Pisidium moitessierianum (Bivalvia, Sphaeriidae): a cryptogenic mollusc in the Great Lakes

Pisidium moitessierianum Paladilhe, 1866, a small pea clam native to Europe, was identified for the first time from the lower Great Lakes basin based on an examination of historical collections of Pisidium performed by V. Sterki in 1894 and 1903 and new material collected during 1997 and 1998. During recent surveys, P. moitessierianum individuals were found in the St. Clair River delta, Lake St. Clair and western Lake Erie, but were not detected in the Detroit River or western Lake Ontario. Pisidium moitessierianum was collected on sand, silty sand and mud substrata from water depths ranging between 0.6 and 5.4 m. Populations occurred at an average density of 51 ind. m−2 and included juveniles and adults. All individuals were less than 2.0 mm in length. We examined the structure of the umbos and hinge, surface sculpture and shape of the shell, and the anatomy of gills, mantle and nephridia in populations from the lower Great Lakes and Ukrainian inland basins (Dnieper River and Lake Beloye). The results indicated that the Great Lakes' pea clams match European specimens of P. moitessierianum in these conchological and anatomical characteristics. As with other nonindigenous sphaeriids in the Great Lakes, P. moitessierianum was likely introduced through shipping activities into the Great Lakes, possibly as early as the 1890s.

An observation of the transportation of Pea Clams, Pisidium adamsi, by Blue-spotted Salamanders, Ambystoma laterale

An observation of the transportation of Pea Clams, Pisidium adamsi, by Blue-spotted Salamanders, Ambystoma laterale

Seasonal respiratory variation and acclimation in the pea clam, Pisidium walkeri sterki

1. 1. Seasonal respiratory variation at field temperatures and at 10° and 20°C are presented for field acclimated clams. Values are presented as Q O 2s based on “shell-free” tissue dry weight and “shell-free” tissue N 2. 2. 2. Q 10 values are presented for all seasons with winter and summer values of about one and three respectively. 3. 3. No size rate differences were found for measurements of oxygen consumption. 4. 4. The seasonal acclimation pattern is complex with the data of early spring indicating Precht's Type I pattern of over-compensation for the over-wintering generation and some of the summer-fall data suggesting Precht's Type V “reverse” acclimation for the summer generation. Seasonal acclimation is discussed in an ecological-environmental context.

Illustrated checklist of pea clams (Mollusca: Bivalvia: Sphaeriidae) from Nepal

The pea clams (Sphaeriidae) of Nepal are represented by 11 taxa. The highest diversity is found in the mid-altitudinal range between 795 and 1570 masl. Pea clams are poorly represented in the high Himalaya and the Terai. Faunal associations are with the Palaearctic and Oriental regions and with Central Asia. Most pea clams are useful indicator species and, owing to their high abundance and long life span, they are useful in monitoring the water quality of streams. 
 
 Key words: Pisidium, Musculium, pea clam, indicator species, Sphaeriidae, Nepal
 
 Himalayan Journal of Sciences 3(5) 2005 p. 57-65