Patricia A. Ramey

Cellular Identity of a Novel Small Subunit rDNA Sequence Clade of Apicomplexans: Description of the Marine Parasite Rhytidocystis polygordiae n. sp. (Host: Polygordius sp., Polychaeta)

ABSTRACT. A new species of Rhytidocystis (Apicomplexa) is characterized from North American waters of the Atlantic Ocean using electron microscopy and phylogenetic analyses of small subunit (SSU) rDNA sequences. Rhytidocystis polygordiae n. sp. is a parasite of the polychaete Polygordius sp. and becomes the fourth described species within this genus. The trophozoites of R. polygordiae were relatively small oblong cells (L=35–55 μm; W=20–25 μm) and distinctive in possessing subterminal indentations at both ends of the cell. The surface of the trophozoites had six to eight longitudinal series of small transverse folds and several micropores arranged in short linear rows. The trophozoites of R. polygordiae were positioned beneath the brush border of the intestinal epithelium but appeared to reside between the epithelial cells within the extracellular matrix rather than within the cells. The trophozoites possessed a uniform distribution of paraglycogen granules, putative apicoplasts, mitochondria with tubular cristae, and a centrally positioned nucleus. The trophozoites were non‐motile and lacked a mucron and an apical complex. Intracellular sporozoites of R. polygordiae had a conoid, a few rhoptries, micronemes, dense granules, and a posteriorly positioned nucleus. Phylogenies inferred from SSU rDNA sequences demonstrated a close relationship between R. polygordiae and the poorly known parasite reported from the hemolymph of the giant clam Tridacna crocea. The rhytidocystid clade diverged early in the apicomplexan radiation and showed a weak affinity to a clade consisting of cryptosporidian parasites, monocystids, and neogregarines.

A new species of Polygordius (Polychaeta: Polygordiidae): from the inner continental shelf and in bays and harbours of the north-eastern United States

A new species of Polygordiidae, Polygordius jouinae sp. nov., along with its distribution, habitat, and reproduction is described. Polygordius jouinae sp. nov., the ¢rst North American Polygordius, is a dominant member of macrofaunal communities on the inner continental shelf, and in bays and harbours from Massachusetts to southern New Jersey. It is distinguished from most other Polygordius species by its non-in£ated, heavily ciliated pygidium, absence of pygidial glands, and a conical (rather than rounded) prostomium. The 18S SSU rDNA from P. jouinae sp. nov. was sequenced and represents the ¢rst named Polygordius species with a DNA reference in GenBank. Spearman rank correlation of sediment grain size with density of P. jouinae sp. nov. at a New Jersey site showed that density was signi¢cantly (P50.05; N ¼92) positively correlated with the proportion of medium to very coarse sand and negatively correlated with the ¢ne sand fractions. Ecologically, P. jouinae sp. nov. is an important macrofaunal species given its widespread distribution and its ¢delity for coarse sand habitats. Thus, its relative abundance may be useful as an indicator of changing sedimentary conditions.

Spontaneous alternation in marine crabs: invasive versus native species.

Organisms ranging from paramecia to humans tend to explore places that have been least recently explored, which is referred to as spontaneous alternation. Although organisms rely on different sources of information in alternating between places, the emergent behavioral pattern is likely advantageous during exploration and foraging. Under this rationale, continuous spontaneous alternation performance of the invasive green crab, Carcinus maenas was assessed and compared with the native blue crab, Callinectes sapidus in a plus-maze submerged in seawater. For the first time spontaneous alternation behavior was demonstrated in Crustacea (i.e., C. maenas) and significant interspecific differences in alternation performance were observed between the invasive versus the native species. Carcinus maneas exhibited a pronouncedly higher spontaneous alternation performance than C. sapidus. Carcinus maneas on average alternated at levels higher than chance, which was not the case for C. sapidus. These observations point to an additional behavioral mechanism that might result in the competitive success of green crabs over blue crabs in areas where they co-occur. Most of the subjects exhibited asymptotic alternation performance from the onset; there was no improvement in their performance over the course of the experimental session. This finding implies the innate nature of this behavioral policy.

Benthic Invertebrate Community Composition and Sediment Properties in Barnegat Bay, New Jersey, 1965−2014

ABSTRACT Taghon, G.L.; Ramey, P.A.; Fuller, C.M.; Petrecca, R.F.; Grassle, J.P., and Belton, T.J., 2017. Benthic invertebrate community composition and sediment properties in Barnegat Bay, New Jersey, 1965−2014. In: Buchanan, G.A.; Belton, T.J., and Paudel, B. (eds.), A Comprehensive Assessment of Barnegat Bay–Little Egg Harbor, New Jersey. Extended time series of estuarine benthic community composition and the chemical and physical properties of sediment are necessary for distinguishing natural variation from possible anthropogenic influences, such as eutrophication. In July 2012, 2013, and 2014, 97 stations, randomly located throughout the Barnegat Bay–Little Egg Harbor estuary, were sampled. Benthic invertebrates were abundant, and the community was, in general, highly diverse. Although there was considerable spatial variability in sediment-particle sizes throughout the estuary, overall the total organic carbon content of the sediments was low (<1%). Comparable historical data from 1965–2010 are spotty in spatial and temporal coverage, limiting comparisons to these recent data. Where comparisons can be made, the abundance and species composition of the benthos and the sediment properties, show few changes in 45 years. Despite high nutrient loading to this coastal bay, its shallow depth and general lack of stratification lead to relatively high dissolved oxygen levels, and it seems likely that heterotrophs in the sediments, both eukaryotes and prokaryotes, are rapidly metabolizing organic matter as it is produced.