Shedd Aquarium (formally the John G. Shedd Aquarium) is an indoor public aquarium in Chicago, Illinois, in the United States. Opened on May 30, 1930, the 5 million US gal (19,000,000 l; 4,200,000 imp gal) aquarium was for some time the largest indoor facility in the world. Today it holds about 32,000 animals.Shedd Aquarium was the first inland aquarium with a permanent saltwater fish collection. It is located on Lake Michigan, on the Museum Campus Chicago, along with the Adler Planetarium and the Field Museum of Natural History.In 2015, the aquarium had 2.02 million visitors. It was the most visited aquarium in the U.S. in 2005, and in 2007, it surpassed the Field Museum as the most popular cultural attraction in Chicago. The aquarium contains 1,500 species, including fish, marine mammals, birds, snakes, amphibians, and insects. The aquarium received awards for "best exhibit" from the Association of Zoos and Aquariums (AZA) for Seahorse Symphony in 1999, Amazon Rising in 2001, and Wild Reef in 2004. It was designated a National Historic Landmark in 1987.
We examined 35 sites across 24 rivers, lakes, and lagoons in El Salvador and documented two native and one non-native freshwater mussel species in addition to the invasive Corbicula. Phylogenetic analyses supported the synonymy of Nephronaias lempensis Marshall, 1926, under Nephronaias goascoranensis (Lea, 1858). Mussel distributions were patchy; Mycetopoda subsinuata (Sowerby, 1868) occurred in soft, lentic habitats, whereas N. goascoranensis occupied a broader range. Sinanodonta pacifica (Heude, 1878), a non-native species, occurred in the upper Lempa basin, and Corbicula showed recent expansion. These results provide essential data for conservation planning.
Obligate endosymbioses between eukaryotes and their single-celled inhabitants form the basis of many ecosystems, yet little is known about the long-term impacts of climate change on them. On coral reefs, extensive studies have shown that climate change-driven heatwaves and other environmental stressors can disrupt the obligate symbiosis between reef-building corals and Symbiodiniaceae, with consequences for coral fitness and survival. However, despite coral symbioses playing a fundamental role in reef resilience to climate change, whether, and at what rate, they recover following heatwave disruption is largely unknown. We used ITS2 DNA metabarcoding to characterise symbiont assemblages in colonies (n = 237; 598 samples) of the brain coral Platygyra ryukyuensis over a decade (2014-2023), spanning from before to long after the 2015-2016 El Niño at its epicentre, Kiritimati, in the central equatorial Pacific. Although before the heatwave only P. ryukyuensis colonies exposed to high levels of chronic local disturbance were dominated by stress-tolerant Durusdinium symbionts, surviving colonies around the atoll transitioned during the heatwave from Cladocopium dominance to Durusdinium dominance. Here, we show that nearly eight years after this transition, these symbiotic partnerships had not recovered, but rather Durusdinium remained entrenched in virtually all (92%) Platygyra colonies. Recovery of symbionts in the genus Cladocopium was severely limited and restricted to taxa distinct from their 'C3' and 'C50a' pre-heatwave congenerics. Moreover, in the three immediate post-heatwave years, many tracked corals, and especially those at low local disturbance, high in-water visibility sites, hosted transient symbiont assemblages codominated by Durusdinium and the previously rare genus Symbiodinium. Our results demonstrate that heatwave-driven symbiont transitions can persist for longer than the average heatwave return time, potentially impairing coral resilience to future extreme weather events.
Urban rivers present unique challenges for basking turtles: shoreline hardening (bulkheads and riprap) often eliminates gradual slopes and natural structures, channelization increases water velocity and reduces complexity, and riparian vegetation removal eliminates thermal refugia and predation cover. Understanding which specific microhabitat features, such as basking structure availability, vegetative cover, and shoreline configuration, enable turtle populations to occupy modified urban waterways is essential for guiding restoration and management in increasingly urbanized landscapes. Using 34 mid-day visual encounter surveys conducted over 2 years (2024 and 2025) in a downtown section of the Chicago River we use occupancy modelling to address the question: Does the amount of shoreline armoring explain turtle habitat use better than natural habitat features like canopy cover? We find that shoreline armoring significantly reduces Emydidae turtle habitat use and explains occupancy better than the significant positive effect of canopy cover. We also found higher occupancy probabilities associated with some unnatural structures like flipped boats and iron beams compared to natural structures like logs and rocks. We conclude that shoreline softening would serve to greatly increase ecosystem services, and where impossible, manmade basking structures would be used by turtles if provided.
Microplastics are widespread in the environment, including in the bodies of freshwater fish, with their concentrations influenced by factors such as proximity to point sources, such as wastewater treatment plants (WWTPs), and trophic level. However, few studies have simultaneously assessed the combined effects of these factors on microplastic abundance in urban stream fish. To do so, we measured microplastics and assessed trophic level via N stable isotope (delta 15N) content in 6 species of small-bodied fishes (species = Lepomis macrochirus Rafinesque, 1819, Neogobius melanostomus [Pallas, 1814], Fundulus notatus [Rafinesque, 1820], Pimephales notatus [Rafinesque, 1820], Notemigonus crysoleucas [Mitchill, 1814], and Dorosoma cepedianum [Lesueur, 1818]) collected upstream, at, and downstream of a large WWTP in Chicago, Illinois, USA. Additionally, we analyzed stomach contents for 2 of these species (L. macrochirus and N. melanostomus). Four of the six species exhibited delta 15N enrichment at and downstream of the WWTP, indicating prolonged residence times at the study sites (i.e., several weeks). Stomach contents of the 2 species measured supported this pattern, showing high chironomid consumption at the WWTP and variable stomach contents elsewhere. For microplastics, 1 species had higher concentrations near the WWTP, but microplastic concentrations did not differ among locations in the other 5 species. We found no evidence of a relationship between delta 15N enrichment and microplastic concentration. Overall, the stable isotope and stomach content results suggest a strong relationship of WWTP effluent with fish diet but not with microplastic concentrations in fish. The results suggest that microplastic concentrations in fish are shaped by interacting, species-specific factors including behavior (i.e., movement and foraging) and physiology (i.e., egestion rates and feeding mechanisms), in addition to proximity to point sources. Our study highlights the complexity of microplastic infiltration into food webs and underscores the need for further research to disentangle the drivers of microplastic accumulation in aquatic organisms.
The regulation of gene expression by epigenetic markers is a growing area of focus for researchers who seek to explain rapid phenotypic acclimatization to environmental change. Yet even as empirical datasets accumulate exponentially, the mechanistic underpinnings of epigenetic changes and their role in connecting environmental variation with the regulation of gene function remain unclear. Here, we use a stochastic model of epigenetic change to generate three testable predictions: (1) that organisms require environmental feedback to track their environments through epigenetic responses, (2) that this tracking requires coordination between the addition and removal of epigenetic markers, and (3) that epigenetically driven tracking is only effective under specific subsets of environmental variability. Despite the intuitiveness of these postulates, few to no experimental studies directly test them. We review correlational evidence consistent with the model's predictions, describe hypothetical mechanisms by which epigenetic strategies could evolve, and clearly identify knowledge gaps and urgent experimental needs in the field. Overall, the field of environmental epigenetics is poised for major advances, which can be enhanced through the continued synthesis of mathematical frameworks and empirical data. ### Competing Interest Statement The authors have declared no competing interest. U.S. National Science Foundation, https://ror.org/021nxhr62, EF-1921356, EF-1921465, EF-1921425, EF-1921149, EF-1921402
