The project is located at Carpinteria Salt Marsh, part of the University of California Reserve System. The marsh is located at 34.40°N, 119.53°W, which is near the city of Carpinteria, CA. The "exp_recruitment" data set includes information on site name (site), latitude (lat) and longitude (long) of each site, cage number (cage), the number of egg-transmitted (egginf) and miracidium-transmitted (mirainf) trematode infections per cage, the biomass of snails within a cage (cagebmdens), and the influence (g^3/4) of final hosts that carry egg-transmitted (eggfhi) and miracidium-transmitted (mirafhi) trematodes. The "exp_risk" data set includes information on site name (site), latitude (lat) and longitude (long) of each site, cage number (cage), the length of each snail (length), the mass of each snail (mass), whether the snail was infected with an egg-transmitted trematode (egginf) or miracidium-transmitted trematode (mirainf), the biomass of snails within a cage (cagebmdens), the biomass of snails in the surrounding area (surrbmdens), and the influence (g^3/4) of final hosts that carry egg-transmitted (eggfhi) and miracidium-transmitted (mirafhi) trematodes. These data support the following publication entitled “Host density increases parasite recruitment but decreases host risk in a snail-trematode system” by J.C. Buck, R.F. Hechinger, A.C. Wood, T.E. Stewart, A.M. Kuris, and K.D. Lafferty http://dx.doi.org/10.1002/ecy.1905.

Each month (except March 2012), we collected detailed data on the infection status of intertidal snails from ten fixed sites as part of a broader effort to understand food webs in California Estuaries. The study site was Carpinteria Salt Marsh Reserve, California USA, (University of California Natural Reserve System), which comprises 9 Ha tidal channels, 2 Ha salt flats, 17 Ha upland habitat, 6 Ha tidal pans, 52 Ha vegetated marsh, 2 Ha tidal flats. Each site was a fixed location in channel or flat habitat, with a diameter approximately 50 m in size, centered at the site location marker used in Kuris et al. (2008). At each site/month, we collected, measured, sexed, and dissected ~58 snails (11,643 dissections total, 5,886 of which were infected with at least one trematode species), describing trematode infections to one of 20 species. To collect snails for dissections, transects were placed randomly at flats sites. For channel sites, transects were placed randomly on the channel bank with the highest snail density. Each transect started 20 cm within the vegetated margin, and extended downslope to the deepest part of the channel or interior of the pan or to a maximum length of 10 m. For every 20 cm decrease in elevation, we established a new transect segment, or quadrat. Specifically, we systematically placed transects at intervals stratified within targeted habitat types: channels, pans, or marsh (or planar habitat that was mixed marsh and pan). For lattitude and longitude coordinates of sites please refer to: Buck, J.C., Wood, A.C., Cook, I.M., and Lafferty, K.D., (in press), Parasite Recruitment and Host Risk in a Snail-Trematode System at Carpinteria Salt Marsh: U.S. Geological Survey data release, http://dx.doi.org/10.5066/F7GX48P2. References: Kuris, A. M., R. F. Hechinger, J. C. Shaw, K. L. Whitney, L. Aguirre-Macedo, C. A. Boch, A. P. Dobson, E. J. Dunham, B. L. Fredensborg, T. C. Huspeni, J. Lorda, L. Mababa, F. Mancini, A. B. Mora, M. Pickering, N. L. Talhouk, M. E. Torchin, and K. D. Lafferty. 2008. Ecosystem energetic implications of parasite and free-living biomass in three estuaries. Nature 454:515-518.

We collected detailed spatial data on the density and size distribution of intertidal snails as part of a broader effort to understand food webs in California estuaries. The survey area was Carpinteria Salt Marsh, California USA, which comprises 9 Ha tidal channels, 2 Ha salt flats, 17 Ha upland habitat, 6 Ha tidal pans, 52 Ha vegetated marsh, 2 Ha tidal flats. Using nearly 4,000 transects in potential snail habitat, we mapped snails throughout the estuary. Specifically, we systematically placed transects at intervals stratified within targeted habitat types: channels, pans, or marsh (or planar habitat that was mixed marsh and pan). At a quarter of the quadrats, we also estimated snail size-frequency distributions. Because we recorded the location of each quadrat, these data can be used to map the distribution of snails throughout this estuary.

Each month (except March 2012), we collected detailed data on the density, size distribution, and infection status of intertidal snails from ten fixed sites as part of a broader effort to understand food webs in California Estuaries. The study site was Carpinteria Salt Marsh Reserve, California USA, (University of California Natural Reserve System), which comprises 9 Ha tidal channels, 2 Ha salt flats, 17 Ha upland habitat, 6 Ha tidal pans, 52 Ha vegetated marsh, 2 Ha tidal flats. Each site was a fixed location in channel or flat habitat, with a diameter approximately 50m in size, centered at the site location marker used in Kuris et al. (2008). At each site/month, we collected, measured, sexed, and dissected ~58 snails. We collected and measured an additional ~42 snails for size-frequency distributions (7,793 snails total). Transects were placed randomly at flats sites. For channel sites, transects were placed randomly on the channel bank with the highest snail density. Each transect started 20 cm within the vegetated margin, and extended downslope to the deepest part of the channel or interior of the pan or to a maximum length of 10 m. For every 20 cm decrease in elevation, we established a new transect segment, or quadrat. Specifically, we systematically placed transects at intervals stratified within targeted habitat types: channels, pans, or marsh (or planar habitat that was mixed marsh and pan). At a quarter of the quadrats, we also estimated snail size-frequency distributions. Because we recorded the location of each quadrat, these data can be used to map the distribution of snails throughout this estuary.

Each month (except March 2012), we collected detailed data on the density, size distribution, and infection status of intertidal snails from ten fixed sites as part of a broader effort to understand food webs in California Estuaries. The study site was Carpinteria Salt Marsh Reserve, California USA, (University of California Natural Reserve System), which comprises 9 Ha tidal channels, 2 Ha salt flats, 17 Ha upland habitat, 6 Ha tidal pans, 52 Ha vegetated marsh, 2 Ha tidal flats. Each site was a fixed location in channel or flat habitat, with a diameter approximately 50m in size, centered at the site location marker used in Kuris et al. (2008). At each site/month, we collected, measured, sexed, and dissected ~58 snails. We collected and measured an additional ~42 snails for size-frequency distributions (7,793 snails total). Transects were placed randomly at flats sites. For channel sites, transects were placed randomly on the channel bank with the highest snail density. Each transect started 20 cm within the vegetated margin, and extended downslope to the deepest part of the channel or interior of the pan or to a maximum length of 10 m. For every 20 cm decrease in elevation, we established a new transect segment, or quadrat. Specifically, we systematically placed transects at intervals stratified within targeted habitat types: channels, pans, or marsh (or planar habitat that was mixed marsh and pan). At a quarter of the quadrats, we also estimated snail size-frequency distributions. Because we recorded the location of each quadrat, these data can be used to map the distribution of snails throughout this estuary.

,Pulmonate snails are the first intermediate host in the life cycle of Bolbophorus damnificus, an important digenetic trematode in Mississippi catfish aquaculture. Two species, the marsh ramshorn snail Planorbella trivolvis and the ghost ramshorn snail Biomphalaria havanensis, commonly inhabit commercial catfish ponds in northwest Mississippi, USA. Low-level, repeated applications of copper sulfate have negative effects on snail reproduction and are effective in reducing snail populations in commercial catfish ponds, although they must be applied judiciously to minimize the phytotoxic and ichthyotoxic effects of copper. At present, little is known regarding population dynamics of these snails and underlying mechanisms driving their proliferation in catfish aquaculture ponds. This study investigated effects of mate availability on egg production in both snail species. Twelve individuals of each species were assigned to one of three treatments based on access to potential mates: continuously (“control”), weekly (“cyclic”), or at a single timepoint (“solitary”). Eggs were collected weekly, and the number of clutches, eggs, and non-viable eggs counted. The study ended at 21 weeks, one week after the final B. havanensis had died. More than 93,000 eggs were counted during the study, with over 60% from P. trivolvis.,

Freshwater mussels of the order Unionida are among the most endangered animal groups globally, but the causes of population declines are often enigmatic with little known about the role of disease. In 2018, we collected wild adult pheasantshell (Actinonaias pectorosa) and mucket (Actinonaias ligamentina) during an epidemiologic survey investigating an ongoing mussel mass mortality event in the Clinch River, USA. Histopathology and transmission electron microscopy showed a novel microsporidian parasite primarily infecting the ovary of pheasantshell. Sequencing of the small subunit rRNA gene produced a 1333 bp sequence with greatest similarity to Pseudonosema cristatellae (AF484694.1; 86.36%; e-value = 0), a microsporidium infecting the freshwater bryozoan (Cristatella mucedo). Microsporidia were observed in 65% (17/26) of the examined female pheasantshell (A. pectorosa) and in no (0/2) female mucket (A. ligamentina), and occurred at mortality and non-mortality sites. Our findings indicate that a novel parasite, Microsporidium clinchi n. sp., is present in pheasantshell in the Clinch River, USA, and while likely not a cause of mass mortality, could reduce fecundity and recruitment in this declining population and threaten the success of reintroductions. Surveillance for M. clinchi n. sp. and evaluation of brood stock and their progeny for microsporidia would therefore be prudent.

Freshwater mussels of the order Unionida are among the most endangered animal groups globally, but the causes of population declines are often enigmatic with little known about the role of disease. In 2018, we collected wild adult pheasantshell (Actinonaias pectorosa) and mucket (Actinonaias ligamentina) during an epidemiologic survey investigating an ongoing mussel mass mortality event in the Clinch River, USA. Histopathology and transmission electron microscopy showed a novel microsporidian parasite primarily infecting the ovary of pheasantshell. Sequencing of the small subunit rRNA gene produced a 1333 bp sequence with greatest similarity to Pseudonosema cristatellae (AF484694.1; 86.36%; e-value = 0), a microsporidium infecting the freshwater bryozoan (Cristatella mucedo). Microsporidia were observed in 65% (17/26) of the examined female pheasantshell (A. pectorosa) and in no (0/2) female mucket (A. ligamentina), and occurred at mortality and non-mortality sites. Our findings indicate that a novel parasite, Microsporidium clinchi n. sp., is present in pheasantshell in the Clinch River, USA, and while likely not a cause of mass mortality, could reduce fecundity and recruitment in this declining population and threaten the success of reintroductions. Surveillance for M. clinchi n. sp. and evaluation of brood stock and their progeny for microsporidia would therefore be prudent.