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A new species of Aulacoseira Thwaites is described from sediment deposits of Surprise Lake, an isolated lake located in the New Jersey Highlands. The species is characterized by (1) a low mantle, (2) unevenly distributed mantle areolae of variable size and shape, and (3) a valve face covered by rounded areolae. The new species is most similar to Aulacoseira biseriata (Grunow in Van Heurk) Houk, R. Klee & H. Tanaka. Both taxa possess frustules with mantles that are low, with irregular pervalvar rows or scattered areolae. However, the two species differ in the shape and pattern of the areolae, the shape and structure of the mantle wall, the shape and depth of the ringleist, and other morphological features. In this study, we present light and scanning electron microscopic images of the new species and compare it to the most similar taxa. [ABSTRACT FROM AUTHOR]

We used sediment diatoms to infer historical changes in total phosphorus (TP) concentration in 26 New York and New Jersey (USA) lakes using a top–bottom approach (i.e., the top of the core represents present conditions and the bottom represents past conditions). Detailed stratigraphic analyses were performed on cores from Greenwood (New Jersey and New York) and Cossayuna lakes (New York). TP reconstructions were performed using 2 weighted-averaging partial-least-squares (WA-PLS) transfer functions: (1) an interregional 278-lake calibration set from northeastern United States (NE-US model: r2boot= 0.69, root mean square error of prediction RMSEP) = 1.8 μg/L); and (2) a regional 33-lake (callibration set from New Jersey and New York (NJ-NY model: r2boot= 0.54, RMSEP = 1.5 μg/L). The NJ-NY model provided better estimates for modern TP but failed to provide reliable estimates for low TP values and reliable modern analogs for half of the bottom samples. Low TP concentrations were better inferred by the NE-US model, which included a higher number of oligotrophic lakes. Average change for all lakes was an increase of 2 to 7 μg/L TP. Greenwood and Cossayuna lakes inferred TP concentrations have increased up to 21 μg/L, presumably as a result of post-settlement anthropogenic activities. The inferred TP temporal changes provide important insight on the magnitude of cultural eutrophication. The use of 2 different inference models demonstrates the advantage of using a regional versus a larger-scale inference model in estimating the degree of change in historical lake TP. Careful interpretation of TP reconstructions can be used to provide reliable estimates of cost-effective targets for lake restoration programs. [ABSTRACT FROM PUBLISHER]

• DNA metabarcoding is an emergent tool for biodiversity assessments. • Benthic eukaryotic assemblages were characterized using18S-V9 rDNA. • Diatoms, water molds, holozoans, green algae, fungi responded to stream impairment. • This approach may be recommended for biomonitoring of stream eukaryotic biota. DNA metabarcoding is rapidly expanding as a new approach to biodiversity assessments and biomonitoring and is especially valuable for characterizing microbial communities in aquatic habitats. When applied to eukaryotic organisms, metabarcoding is usually targeting specific taxonomic groups, such as macroinvertebrates, fungi, diatoms, or other protists. The goal of this study was to explore the potential use of metabarcoding of entire biofilm eukaryotic assemblages for the purpose of stream biomonitoring. We sampled 14 stream sites in New Jersey, USA along an impairment gradient and characterized rock biofilm assemblages using Illumina Mi-Seq sequencing of the V9 hypervariable region of 18S rDNA following the Earth Microbiome Project (EMP) protocol. We also enumerated diatoms from the same samples to compare DNA metabarcoding results with morphological assessments. Among the 5866 unique rDNA sequence variants, the fungal and holozoan sequences were the most diverse, while diatom sequences were the most abundant in most sites. Among-site variability of assemblage composition was significantly higher than within-site variability of field and lab replicates, which indicates an acceptable level of reproducibility of the method. Different taxonomic groups of eukaryotes exhibited similar, but not identical patterns of assemblage variation in response to underlying environmental gradients. Both morphological and metabarcoding approaches recovered strong relationships between diatom assemblage composition and water quality impairment. Several other groups of eukaryotes, such as fungi, peronosporomycetes, green algae, and holozoans had only slightly weaker response to water quality impairment than diatoms. These findings suggest that molecular characterization of biofilm eukaryotic assemblages can be an effective tool for monitoring stream biota and its responses to disturbance even if the taxonomic assignments of sequences are only partially resolved. [ABSTRACT FROM AUTHOR]