This dataset represents microscopy cell counts from multivariate mesocosm experiments conducted with a natural phytoplankton community from Narragansett Bay, RI. These data were assessed in Anderson et al. The Interactive Effects of Temperature and Nutrients on a Spring Phytoplankton Community (in prep). For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/848977 Copyright: https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0

Despite increasing interest in winter limnology, few studies have examined under-ice zooplankton communities and the factors shaping them in different types of temperate lakes. To better understand drivers of zooplankton community structure in winter and summer, we sampled 13 lakes across a large trophic status gradient for crustacean zooplankton abundance, taxonomic and functional community composition and C/N stable isotopes. Average winter zooplankton densities were one-third of summer densities across the study lakes. Proportionally, cladocerans were more abundant in summer than winter, with the opposite pattern for calanoids and cyclopoids. In green (eutrophic) lakes, zooplankton densities were higher under the ice than in brown (dystrophic) and blue (oligotrophic) lakes, suggesting better conditions for zooplankton in productive lakes during winter. Overall, zooplankton communities were more similar across lakes under the ice than during the open water season. Feeding group classification showed a decrease in herbivore abundance and an increase in predators from summer to winter. C/N stable isotope results suggested higher lipid content in overwintering zooplankton and potentially increased reliance on the microbial loop by winter zooplankton. Our results show substantial variation in the seasonality of zooplankton communities in different lake types and identify some of the factors responsible for this variation.

As groundwater depletion becomes a global phenomenon, inland lake ecosystems are being impacted by decreasing groundwater supply. While the current trend of rapid surface warming of inland lakes continues, the deep waters can resist changes, depending on the nature of surface water - groundwater interactions. However, the effects of these interactions on lake processes are not fully understood. Here we investigate the role of groundwater on coupled biophysical processes in a deep, dimictic, groundwater-fed lake using mechanistic models combined with data from field observations. Although excess nutrient inputs are the most commonly cited reason for algal blooms, here we show that algal blooms in inland lakes can also appear due to a decreasing groundwater supply while all other factors remain the same. Results indicate that decreasing groundwater supply to lakes leads to elevated hypolimnetic temperatures, enhanced algal growth rates and algal blooms, and oxygen depletion, thus exacerbating the negative effects of surface warming. Our work suggests that globally declining groundwater supplies may have a significant negative effect on water quality of inland lakes by accelerating water column warming and stimulating algal growth, especially when the groundwater contribution to the lake system is significant compared to riverine discharge. The work provides insights for management efforts to improve the resilience of groundwater-dependent ecosystems in the face of external stressors.

Phytoplankton are key players in global biogeochemical cycles, and the effects of ocean warming on their carbon-nitrogen-phosphorus (CNP) stoichiometry, photosynthesis, size, morphology, growth rates, and other traits are of great ecological consequence. The physiological mechanisms of adaptation to temperature in phytoplankton are poorly understood, as are the consequences of the evolution of these processes (e.g., nutrient uptake, photosynthesis) for global biogeochemistry. In general, high temperatures favor smaller cells with higher surface area-to-volume ratios, but repeatable patterns in cellular CNP stoichiometry across temperature remain elusive. Here, we compared thermal reaction norms for cellular C, N, P, and chlorophyll a (Chl a) content and for carbon assimilation rate in replicate populations of the marine diatom Thalassiosira pseudonana evolved for 500 generations at 16 degrees C and 31 degrees C. We also examined the thermal reaction norms for cell volume and morphological traits. T. pseudonana has a cylindrical frustule and likely primarily exchanges materials with the environment through the round valve faces. We found that the 31 degrees C-selected T. pseudonana populations had smaller cells and higher per-biovolume densities of nutrients and Chl a than the 16 degrees C-selected populations across assay temperatures but there were no detectable patterns in CNP stoichiometry. The 31 degrees C-selected populations also had higher valve surface area-to-cell volume ratio that increased more with temperature, suggesting better nutrient uptake capabilities than in the 16 degrees C-selected populations. Our study demonstrates that temperature-dependent physiological plasticity may evolve differently at different temperatures and suggests that future phytoplankton communities will consist of smaller, more nutrient-dense cells.

There is a growing consensus that traits offer a powerful way to examine the relationship between the environment, organismal strategies, species interactions, and ecological success. To date, trait-based research has largely been focusing on individual trophic levels and not on cross-level interactions. Looking at traits not only within but across trophic levels and identifying traits that together define trophic interactions holds a great potential for understanding the mechanisms of interactions. Here, we outline the conceptual foundation for cross-trophic trait-based frameworks, using planktonic food webs as an example. First, we compile a list of traits important within different individual trophic levels and show that there are traits that are common across trophic levels ("universal" traits), as well as trophic level-specific traits. Next, we focus on traits that characterize interactions across trophic levels, focusing on two types of interaction-grazer-primary producer and host-parasite, identifying the similarities and differences between these interactions. We outline the trait hierarchies that define possible and realized intertrophic interactions and their strengths. We then highlight the importance of trade-offs among those traits in shaping interactions and explaining general patterns in the structure and function of food webs. Finally, we discuss the environmental influences on traits, their eco-evolutionary responses to changing conditions and how those responses may alter trophic interactions. The extension of trait-based approaches from individual trophic levels to food webs and different trophic interactions should stimulate further conceptual development, enrich the field of aquatic sciences, and provide a framework to better predict global change effects on ecosystems.

A complex interplay of environmental variables impacts phytoplankton community composition and physiology. Temperature and nutrient availability are two principal factors driving phytoplankton growth and composition, but are often investigated independently and on individual species in the laboratory. To assess the individual and interactive effects of temperature and nutrient concentration on phytoplankton community composition and physiology, we altered both the thermal and nutrient conditions of a cold-adapted spring phytoplankton community in Narragansett Bay, Rhode Island, when surface temperature was 2.6 degrees C and chlorophyll > 9 mu g L-1. Water was incubated in triplicate at -0.5 degrees C, 2.6 degrees C, and 6 degrees C for 10 d. At each temperature, treatments included both nutrient amendments (N, P, Si addition) and controls (no macronutrients added). The interactive effects of temperature and resource availability altered phytoplankton growth and community structure. Nutrient amendments resulted in species sorting and communities dominated by larger species. Under replete nutrients, warming tripled phytoplankton growth rates, but under in situ nutrient conditions, increased temperature acted antagonistically, reducing growth rates by as much as 33%, suggesting communities became nutrient limited. The temperature-nutrient interplay shifted the relative proportions of each species within the phytoplankton community, resulting in more silica rich cells at decreasing temperatures, irrespective of nutrients, and C : N that varied based on resource availability, with nutrient limitation inducing a 47% increase in C : N at increasing temperatures. Our results illustrate how the temperature-nutrient interplay can alter phytoplankton community dynamics, with changes in temperature amplifying or exacerbating the nutrient effect with implications for higher trophic levels and carbon flux.

Mathematica code for "A general framework for species-abundance distributions: linking traits and dispersal to explain commonness and rarity", Ecology Letters. Requires: Wolfram Mathematica (tested on v13.1) EcoEvo package (tested on v1.6.4) This research was supported by the Simons Foundation grant 343149, NSF grant DEB 17-54250 and NASA grant 80NSSC18K1084. Copyright: Creative Commons Attribution 4.0 International Open Access

The chromatin associated with the nuclear lamina (NL) is referred to as lamina-associated domains (LADs). Here, we present an adaptation of the tyramide-signal amplification sequencing (TSA-seq) protocol, which we call chromatin pull down-based TSA-seq (cTSA-seq), that can be used to map chromatin regions at or near the NL from as little as 50 000 cells. The cTSA-seq mapped regions are composed of previously defined LADs and smaller chromatin regions that fall within the Hi-C defined B-compartment containing nuclear peripheral heterochromatin. We used cTSA-seq to map chromatin at or near the assembling NL in cultured cells progressing through early G1. cTSA-seq revealed that the distal ends of chromosomes are near or at the reassembling NL during early G1, a feature similar to those found in senescent cells. We expand the use of cTSA-seq to the mapping of chromatin at or near the NL from fixed-frozen mouse cerebellar tissue sections. This mapping reveals a general conservation of NL-associated chromatin and identifies global and local changes during cerebellar development. The cTSA-seq method reported here is useful for analyzing chromatin at or near the NL from small numbers of cells derived from both in vitro and in vivo sources.

Our past GAPplanetS survey over the last 5 years with the MagAO visible AO system discovered the first examples of accreting protoplanets (by direct observation of H-alpha emission). Examples include LkCa15 b (Sallum et al. 2015) and PDS70 b (Wagner et al. 2018). In this paper we review the science performance of the newly (Dec. 2019) commissioned MagAO-X extreme AO system. In particular, we use the vAPP coronagraphic contrasts measured during MagAO-X first light. We use the Massive Accreting Gap (MAG) protoplanet model of Close 2020 to predict the H-alpha contrasts of 19 of the best transitional disk systems (ages 1-5 Myr) for the direct detection of H-alpha from accretion of hydrogen onto these protoplanets. The MAG protoplanet model applied to the observed first light MagAO-X contrasts predict a maximum yield of 46 +/- 7 planets from 19 stars (42 of these planets would be new discoveries). This suggests that there is a large, yet, unexplored reservoir of protoplanets that can be discovered with an extreme AO coronagraphic survey of 19 of the best transitional disk systems. Based on our first light contrasts we predict a healthy yield of protoplanets from our MaxProtoPlanetS survey of 19 transitional disks with MagAO-X.