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Numerous per‐ and polyfluoroalkyl substances (PFAS) are of growing concern worldwide due to their ubiquitous presence, bioaccumulation and adverse effects. Surface waters in the United States have displayed elevated concentrations of PFAS, but so far discrete water sampling has been the commonly applied sampling approach. In the present study we field‐tested a novel integrative passive sampler, a microporous polyethylene tube, and derived sampling rates (Rs) for nine PFAS in surface waters. Three sampling campaigns were conducted, deploying polyethylene tube passive samplers in the effluent of two wastewater treatment plant (WWTP) effluents and across Narragansett Bay (Rhode Island, USA) for 1 month each in 2017 and 2018. Passive samplers exhibited linear uptake of PFAS in the WWTP effluents over 16–29 days, with in situ Rs for nine PFAS ranging from 10 ml day−1 (perfluoropentanoic acid) to 29 ml day−1 (perfluorooctanesulfonic acid). Similar sampling rates of 19 ± 4.8 ml day−1 were observed in estuarine field deployments. Applying these Rs values in a different WWTP effluent predicted dissolved PFAS concentrations mostly within 50% of their observations in daily composite water samples, except for perfluorobutanoic acid (where predictions from passive samplers were 3 times greater than measured values), perfluorononanoic acid (1.9 times), perfluorodecanoic acid (1.7 times), and perfluoropentanesulfonic acid (0.1 times). These results highlight the potential use of passive samplers as measurement and assessment tools of PFAS in dynamic aquatic environments. Environ Toxicol Chem 2022;41:2375–2385. © 2022 SETAC [ABSTRACT FROM AUTHOR]

Niche theory, the oldest, most established community assembly model, predicts that in sympatry, the realized niche will contract due to negative interspecific interactions, but fails to recognize the effects of positive interactions on community assembly. The stress gradient hypothesis predicts that positive interactions expand realized niches in stressful habitats. We tested the predictions of the stress gradient hypothesis in a cobble beach model system across both physical and biological stress gradients. We transplanted seven common littoral species within, adjacent to, and below Spartina alterniflora cordgrass stands in control, cage control, predator exclusion cage, shade, and shaded predator exclusion cage treatments to test the hypothesis that cordgrass expands intertidal organism habitats. On cobble beaches, cordgrass ameliorates physical and predation stresses, expanding the distribution and realized niches of species to habitats in which they cannot live without facilitation, suggesting that niche theory and species distribution models should be amended to accommodate the role of positive interactions in community assembly. [ABSTRACT FROM AUTHOR]

Macroalgal bloom-forming species occur in coastal systems worldwide. However, due to overlapping morphologies in some taxa, accurate taxonomic assessment and classification of these species can be quite challenging. We investigated the molecular and morphological characteristics of 153 specimens of bloom-forming Ulva located in and around Narragansett Bay, RI, USA. We analyzed sequences of the nuclear internal transcribed spacer 1 region ( ITS1) and the chloroplast-encoded rbcL; based on the ITS1 data, we grouped the specimens into nine operational taxonomic units ( OTUs). Eight of these OTUs have been previously reported to exist, while one is novel. Of the eight OTUs, all shared sequence identity with previously published sequences or differed by less than 1.5% sequence divergence for two molecular markers. Previously, 10 species names were reported for Ulva in Rhode Island (one blade and nine tube-forming species) based upon morphological classification alone. Of our nine OTUs, three contained blade-forming specimens ( U. lactuca, U. compressa, U. rigida), one OTU had a blade with a tubular stipe, and six contained unbranched and/or branched tubular morphologies (one of these six, U. compressa, had both a blade and a tube morphology). While the three blade-forming OTUs in Narragansett Bay can frequently be distinguished by careful observations of morphological characteristics, and spatial/temporal distribution, it is much more difficult to distinguish among the tube-forming specimens based upon morphology or distribution alone. Our data support the molecular species concept for Ulva, and indicate that molecular-based classifications of Ulva species are critical for proper species identification, and subsequent ecological assessment or mitigation of Ulva blooms. [ABSTRACT FROM AUTHOR]

Natural stress gradients can reduce predation intensity and increase prey abundances. Whether the harsh conditions of anthropogenic habitat degradation can similarly reduce predation intensity and structure community dynamics remains largely unexplored. Oxygen depletion in coastal, waters (hypoxia) is a form of degradation that has recently emerged as one of the greatest threats to coastal ecosystems worldwide due to increased rates of eutrophication and climate change. I conducted field experiments and surveys to test whether relaxed predation could explain the paradoxically high abundance of clams that have' sustained a fishery in a degraded estuary with chronic hypoxic conditions. Hypoxia reduced predation on all experimental species but enhanced the long-term survivorship of only sufficiently hypoxia-tolerant prey due to periodic extreme conditions. As a consequence, only the harvested quahog clam (Mercenaria inercenaria) thrived in hypoxic areas that were otherwise rendered dead zones with depauperate diversity and low abundances of other species. This suggests that enhanced populations of some key species may be part of a predictable nonlinear community response that sustains ecosystem services and masks overall downward trends of habitat degradation. [ABSTRACT FROM AUTHOR]

Although primary productivity in salt marshes is thought to be controlled by physical forces, recent evidence suggests that human disturbances can drive a switch to consumer control in these ecologically valuable ecosystems. We tested the hypothesis that nitrogen enrichment can trigger consumer control in salt marshes in Narragansett Bay, Rhode Island, with (1) a field experiment in which we manipulated nutrient availability (with nutrient additions) and insect herbivory (with insecticide application), (2) a survey of 20 salt marshes that examined the relationship between marsh nutrient status and herbivore pressure, and (3) insect herbivore removal at high and low nutrient input sites to directly test the hypothesis that nutrient enrichment is increasing insect herbivory in these marshes. Experimental nitrogen eutrophication initially increased plant productivity but eventually led to reduced plant biomass due to insect herbivory, and our surveys revealed that marsh nitrogen supply was a good predictor of herbivore damage to plants. Insects had minimal impacts on primary productivity in pristine marshes, but suppressed primary productivity in eutrophic salt marshes by 50–75%. Thus, eutrophication is currently triggering consumer suppression of primary productivity in New England salt marshes and may ultimately jeopardize the ecological and societal services these systems provide. [ABSTRACT FROM AUTHOR]

The article discusses Computer-Aided Tomography (CT) scanning technology was applied to intact sediment cores to study estuary benthic communities. It discusses use of attenuation of X-rays to differentiate between sediment and water contained in macrobenthic tubes and tunnels. It also mentions measurement of percentage of tube and tunnel area (PTTA) to assess and monitor the effects of organic carbon loading on benthic communities in Narragansett Bay, Rhode Island.

DCMU-enhanced fluorescence and extracted chlorophyll a were simultaneously measured in Narragansett Bay, Rhode Island and the MERL (Marine Ecosystems Research Laboratory) mesocosms during the 1985 brown tide bloom. Marked differences in the relationship between these variables were observed as the phytoplankton community shifted from dominance by picoalgae to diatoms. The fluorescence to chlorophyll a ratio was significantly (P < 0.05) higher in the mesocosms and the bay when the brown tide species (Aureoeoccus anophagefferens Hargraves et Sieburth) dominated the phytoplankton community compared with other taxa. Although several factors could have affected the relationship we believe the high ratios are related to the pigment composition and/or small size of the brown tide organism. [ABSTRACT FROM AUTHOR]

The brown tide picoalga Aurecoccus anophagefferens Hargraves et Sieburth was present in approximately equal numbers in 12 large sale (13,000 L) mesocosms at the start of a nutrient addition experiment in June 1985. Increases in abundance in untreated systems mimicked the pattern of bloom development in Narragansett Bay, Rhode Island, the seawater source for the experiment in June 1985. Increases in abundance in untreated systems mimicked the pattern of bloom development in Narragansett Bay, Rhode Island, the seawater source for the experiment. Aureococcus increased to maximal values of 2.6 × 10[sup9] cells · L[sup-1] and persisted at high numbers (> 10[sup8] cells·L[SUP-1]) for 7-8 weeks> In nutrient addition tanks, the picoalgae bloomed briefly (1-3 weeks) buts rapidly declined to the usual level (∼10[sup2] cells·L[SUP-1] for eukaryotic alage in Narragansett Bay. The decline in picoalgae in all nutrient treated followed by an increase in total diatoms in all nutrient treated tanks. Mean picoalgae abundance in the mesocosms and the bay was significantly (P < 0.05) and inversely correlated (r = -0.93) with mean concentration of dissolved inorganic nitrogen. The persistence of the brown tide species in control mesocosms nad Narragansett Bay appears related to its ability to grow at very low concentrations of dissolved inorganic nitrogen, Levels previously shown to limits diatom growth [ABSTRACT FROM AUTHOR]

Clones of Skeletonema costatum (Grev). Cl. isolated from Narragansett Bay. R. I., during different seasons were grouped according to their electrophoretic banding patterns. The growth rates, pg chlorophyll cell[sup-1], carbon uptake cell[sup-1]h[sup-1], and carbon uptake pg chl[sup-1] h[sup-1] were measured at 20°C. in a 14;10 h L:D cycle at 180 μE m[sup-2] s[sup-1]. Statistically significant sources of variation were found among groups of clones in growth rate, pg chl cell[sup-1], and carbon uptake pg chl[sup-1] h[sup-1]. It was concluded that there is a significant relationship between the physiological characteristics of clones isolated from populations in different seasons and patterns of genetic variation inferred from the electrophoretic studies. However, genetic diversity detected by bonding patterns trends in underestimate the total genetic diversity in natural populations. The groups of clones most common in summer bloom populations had significantly higher growth rates, lower values of pg chl cell[sup-1] and higher rates of carbon uptaks pg chl[sup-1] h[sup-1] at 20°C than did the group of clones most common in winter bloom populations. However, differences among groups in these parameters at 20°C alone cannot account for the seasonal cycling of genetically variable populations of Skeletonema in Narragnasell Bay. The range of growth rates among clones of this species is 0.1-5.0 diversions d[sup-1] under a single set of temperature and light conditions. Chlorophyll concentrations range from 0.2-1.7 pg chl. Cell[sup-1] and carbon uptake pg chl[sup-1] h[sup-1] varies by a factor of 7 among clones. The range of phystological variations in this species means that it is difficult to use laboratory studies of single clones to analyze the responses of natural populations of Skeletonema. [ABSTRACT FROM AUTHOR]