Objective Remote underwater video (RUV) is a noninvasive survey technique that has long been used in marine ecosystems and is now gaining interest among freshwater fisheries scientists. Our objective was to test the efficacy of RUV for assessing fish species richness and abundance in the littoral zone of two water bodies in central Ontario, Canada.Methods With 133 deployments, we used RUV, minnow traps, snorkel surveys, and beach seine netting (the latter in river sites only) to survey fish assemblages and compared their estimates of species richness using species accumulation curves and generalized linear models. We compared maxN (a conservative estimate of abundance from RUV) to estimates of fish density from seine netting.Results We found that RUV estimated similar or higher species richness when compared with minnow traps and snorkeling but underestimated species richness relative to seine netting, which captured several uncommon small-bodied fishes that RUV failed to detect. The maxN was correlated with density estimates from seine netting for only 4 out of 11 species and life stages, suggesting that maxN is only a useful index of abundance for some species. Remote underwater video was sufficiently sensitive to detect a major interannual change in abundance of the invasive Round Goby Neogobius melanostomus, but the magnitude of change was much lower than the increase in density estimated by seine netting.Conclusions Collectively, the data reported here suggest that RUV is a useful tool, especially when used in conjunction with other methods or where other fisheries survey methods (e.g., electrofishing and netting) are not possible, such as for community groups interested in developing their own monitoring programs. Remote underwater video (RUV) could be an alternative to capture-based techniques. Here, we compared RUV to conventional methods in freshwater. Despite lower detection of small-bodied fishes, we found that RUV was an excellent sampling tool, especially when combined with other methods, or where other methods are impractical.

Ocean warming is the greatest threat to coral reefs, prompting a need to accurately monitor in situ temperatures. Advancements in sensing technologies have led to a proliferation of temperature loggers being deployed globally. However, appropriate deployment of loggers–essential for measurement accuracy in an ecosystem where changes of 1ºC can cause widespread mortality–is often overlooked. For example, loggers deployed in direct sunlight are known to overestimate temperature, but the prevalence of shading loggers is unknown. Here, we survey recent literature to assess the current state of temperature logger use on coral reefs. We then performed lab and field trials on 10 models that span a range of prices and accuracies to evaluate logger performance and assess efficacies of shading techniques. Of the 329 studies we reviewed, >40% of studies deployed loggers shallower than 5 m, yet <5% reported shading loggers, revealing the potential for bias in existing datasets. In field tests, solar bias varied significantly across loggers; the most popular model suffered the largest bias of >2.5ºC, while other models were less affected by irradiance. Wrapping loggers in tape reduced temperature bias, but under high irradiance measurement error still exceeded 0.8ºC. Shading loggers under an opaque object completely eliminated solar bias. We demonstrated a strong linear relationship between in situ irradiance and temperature error and quantified irradiance thresholds for which error >0.5°C can be expected. We then modeled the temperature bias expected for the most popular logger model using in situ irradiance data, showing that errors >2ºC can exist across multiple depths. Our findings reveal pervasive underreporting of logger deployment methods in coral reef studies, highlighting the need to consider the possibility of bias when comparing studies or integrating different in situ temperature records. Future studies should strive to transparently describe deployment methods and appropriately shade loggers.

Long-term monitoring of individual coral colonies is important for understanding variability between and within species over time in the context of thermal stress. Here, we analyze an 11-year time series of permanent benthic photoquadrats taken on Palmyra Atoll, central Pacific, from 2009 to 2019 to track the growth (i.e., increase in live planar area), pigmentation or lack thereof (“discoloration”), partial or whole-colony mortality, survival, and regrowth of 314 individual coral colonies of nine focal species from two reef habitat types. During this period, thermal anomalies occurred on Palmyra in conjunction with El Niño-Southern Oscillation events in both 2009 and 2015, of which the latter heatwave was longer-lasting and more thermally-severe. We found that coral responses varied by habitat, within and among species, and/or according to the degree of accumulated thermal stress. Nearly all species, particularly Stylophora pistillata and Pocillopora damicornis, responded more negatively to the 2015 heatwave in terms of colony-specific discoloration and reduction in live planar area. While discoloration was more prominent at the shallower reef terrace compared to the fore reef for this subset of colonies, the reef terrace exhibited greater stability of community-wide coral cover. Colony fate was associated with severity of discoloration at the time of warming: one year following the 2009 heatwave, more severely discolored colonies were more likely to grow, yet following the second heatwave in 2015, colonies were more likely to experience shrinkage or mortality. However, colonies that were more severely discolored in 2009 were not necessarily more discolored in 2015, suggesting that colony-specific factors may be more influential in governing responses to thermal stress.

Marine heatwaves are triggering coral bleaching events and devastating coral populations globally, highlighting the need to identify processes promoting coral survival. Here, we show that acceleration of a major ocean current and shallowing of the surface mixed layer enhanced localized upwelling on a central Pacific coral reef during the three strongest El Niño–associated marine heatwaves of the past half century. These conditions mitigated regional declines in primary production and bolstered local supply of nutritional resources to corals during a bleaching event. The reefs subsequently suffered limited post-bleaching coral mortality. Our results reveal how large-scale ocean-climate interactions affect reef ecosystems thousands of kilometers away and provide a valuable framework for identifying reefs that may benefit from such biophysical linkages during future bleaching events.

Urban streams are impacted by multiple anthropogenic environmental stressors that exert considerable pressure on resident fish populations. Species such as brook trout (Salvelinus fontinalis) are particularly vulnerable because urban environments typically limit the cold oxygenated water required by all life stages. To understand factors associated with native brook trout movement in urban streams, we monitored 20 radio-tagged individuals from late summer through the spawning season in autumn, and modelled how movement was influenced by body size and habitat. Tracking occurred in two adjacent streams that differed in forest cover and channelization. In both streams, brook trout mainly travelled upstream, particularly at the onset of the autumn spawning season. Larger individuals exhibited greater movements, and habitat complexity imposed stronger effects in larger individuals. Greater movements were made into locations of shallower depth and lower conductivity, although these factors were conflated with movement into upstream locations. This study addresses a fundamental knowledge gap in urban stream ecology by providing detailed information on the movement of a key indicator species of aquatic ecosystem health.

AbstractThe ventral lateral geniculate nucleus (vLGN) is a retinorecipient region of thalamus that contributes to a number of complex visual behaviors. Retinal axons that target vLGN terminate exclusively in the external subdivision (vLGNe), which is also transcriptionally and cytoarchitectonically distinct from the internal subdivision (vLGNi). While recent studies shed light on the cell types and efferent projections of vLGNe and vLGNi, we have a crude understanding of the source and nature of the excitatory inputs driving postsynaptic activity in these regions. Here, we address this by conductingin vitrowhole-cell recordings in acutely prepared thalamic slices and using electrical and optical stimulation techniques to examine the postsynaptic excitatory activity evoked by the activation of retinal or cortical layer V input onto neurons in vLGNe and vLGNi. Activation of retinal afferents by electrical stimulation of optic tract or optical stimulation of retinal terminals resulted in robust driver-like excitatory activity in vLGNe. Optical activation of corticothalamic terminals from layer V resulted in similar driver-like activity in both vLGNe and vLGNi. Using a dual-color optogenetic approach, we found that many vLGNe neurons received convergent input from these two sources. Both individual pathways displayed similar driver-like properties, with corticothalamic stimulation leading to a stronger form of synaptic depression than retinogeniculate stimulation. We found no evidence of convergence in vLGNi, with neurons only responding to corticothalamic stimulation. These data provide insight into the influence of excitatory inputs to vLGN and reveal that only neurons in vLGNe receive convergent input from both sources.

Objective: Localize visuospatial dysfunction in Alzheimer's disease (AD) using atrophy and network mapping techniques, and identify whether clock-draw or clock-copy is a better test of parietal lobe dysfunction. Background: Visuospatial dysfunction in AD is common and a direct contributor to falls, car accidents and loss of independence. Better understanding of visuospatial network dysfunction in AD allows for earlier intervention and improved safety. Atrophy mapping studies have localized visuospatial dysfunction to multiple brain regions suggesting it maps to a network. Here, cortical thickness and atrophy network maps were created and compared to clock-copy and clock-draw scores to identify the network underlying visuospatial dysfunction in AD using the Alzheimer's Disease Neuroimaging Initiative (ADNI). Design/Methods: Initial analyses were run using ADNI1 then validated using independent subjects in ADNI2. Cortical thickness was directly compared to clock-draw and clock-copy scores identifying brain regions directly associated with performance. A general-linear-model was generated from each cohort's healthy controls and used to estimate expected cortical thickness for AD subjects. Atrophy maps were generated using multiple Z-score cutoffs at a voxel-wise level. Atrophy network maps were generated using the normative connectome and compared to clock-copy and clock-draw scores. Results: Single-subject cortical thickness maps compared directly to clock-copy or clock-draw scores did not identify any voxels that correlated with scores meeting FWE p<0.05. Atrophy network maps compared to clock-draw scores identified a network but not voxels meeting FWE p<0.05. However, atrophy network mapping identified a map centered on the bilateral angular gyri significantly correlating with clock-copy scores. Clock-copy atrophy network maps showed higher reproducibility than clock-draw. Conclusions: Our results show that clock-draw and clock-copy scores map to networks rather than single brain regions. Clock-draw maps to a distributed brain network while clock-copy maps to the angular gyrus and is more reproducible. Clock-copy is a more specific measure of parietal lobe function in AD than clock-draw. Disclosure: Dr. Baratono has stock in moderna. Dr. Fox has received personal compensation in the range of $500-$4,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Wiley. Mr. Drew has nothing to disclose.

The prevalence of coral bleaching due to thermal stress has been increasing on coral reefs worldwide. While many studies have documented how corals respond to warming, fewer have focused on benthic community responses over longer time periods or on the response of non-coral taxa (e.g., crustose coralline algae, macroalgae, or turf). Here, we quantify spatial and temporal changes in benthic community composition over a decade using image analysis of permanent photoquadrats on Palmyra Atoll in the central Pacific Ocean. Eighty permanent plots were photographed annually between 2009 and 2018 on both the wave-exposed fore reef (FR, 10 m depth, n = 4 sites) and the wave-sheltered reef terrace (RT, 5 m depth, n = 4 sites) habitats. The El Niño events of 2009–2010 and 2015–2016 resulted in acute thermal stress and coral bleaching was observed at both reef habitats during these events. Across 10 yr and two bleaching events, the benthic community structure on Palmyra shows evidence of long-term stability. Communities on the RT exhibited minimal change in percent cover of the dominant functional groups, while the FR had greater variability and minor declines in hard coral cover. There was also spatial variation in the trajectory of each site through time. Coral cover decreased at some sites 1 yr following both bleaching events and was replaced by different algal groups depending on the site, yet returned to pre-bleaching levels within 2 yr. Overall, our data reveal the resilience of calcifier-dominated coral reef communities on Palmyra Atoll that have persisted over the last decade despite two bleaching events, demonstrating the capacity for these reefs to recover from and/or withstand disturbances in the absence of local stressors.

Invasive species have the potential to damage ecosystems outside their native range. At an invasion front, individuals are faced with the unfamiliar conditions of a novel environment. Therefore, certain behavioural traits such as boldness and movement likely play a role in invasion ecology. If behavioural traits of this kind are influenced by differing selection pressures between demographic groups of the same species, this could have broad implications for the management of expanding invasion fronts. To determine whether the invasive round goby (Neogobius melanostomus, Pallas, 1814) exhibits sex- and habitat-based differences in boldness and movement across the invasion front, the authors assessed individual movement and exploration tendency under controlled lab settings using video analysis in a behavioural assay. N. melanostomus from lakes tended to be bolder than those from streams, and females tended to be bolder than males. This study provides evidence for sex- and habitat-based differences in behaviour in this globally invasive species that the authors hope will assist in forming the foundation for contextually appropriate management strategies.

Corals in the northern Red Sea exhibit high thermal tolerance despite the increasing heat stress. It is assumed that corals throughout the Red Sea have similar bleaching thresholds (32°C or higher), and hence greater bleaching tolerance of corals in the northern Red Sea region is likely due to lower ambient water temperatures (25–28°C) that remain well below the corals’ physiological maxima. Whether bleaching patterns across the Red Sea are independent of the local maximum monthly mean of seawater temperature and aligned with an assumed 32°C threshold has yet to be determined. Here, we used remotely sensed surface sea temperature data spanning 1982–2020 to model spatial distributions of Degree Heat Weeks across the Red Sea in relation to assumed coral thermal threshold values of 30, 31, and 32°C. We also used the Coupled Model Intercomparison Project Phase 5 model outputs to predict warming trends in the Red Sea under different greenhouse gas representative concentration pathways (RCPs). We show that applying 32°C thresholds dramatically reduces effective Degree Heat Weeks in the north, but not in central or southern Red Sea regions, a finding that is consistent with historical bleaching observations (1998–2020) throughout the Red Sea. Further, model predictions under the most extreme RCP8.5 scenario exhibited ~3°C warming by the end of the 21 st century throughout the Red Sea with less pronounced warming for the northern Red Sea (2–2.5°C) compared to the central and southern regions (2.7–3.1°C).This warming rate will remain below the assumed thermal threshold for the northern Red Sea which should help this region to serve as refugia (i.e., maintaining favorable temperatures) for corals to persist for decades ahead. Together, our results support the notion that corals have similar thresholds throughout the Red Sea; hence, coral bleaching thresholds are independent of the local maximum monthly mean. Consequently, where regional warming projections suggest the northern Red Sea will not reach assumed bleaching thresholds (32°C) before the end of the 21 st century, coral reefs in the northern region may be among the last standing against climate change.

1. Carbon isotope fingerprinting, or multivariate analysis using δ 13 C values of indi vidual compounds, is a powerful tool in ecological studies, particularly measure ments of essential amino acids (EAA δ 13 C). Despite the widespread application of this technique, there has been little methodological validation to determine (a) whether multivariate EAA δ 13 C signatures (fingerprints) of primary producer groups vary across space and time and (b) what biochemical mechanisms drive these patterns. 2. Here, we evaluate the spatiotemporal consistency in EAA δ 13 C fingerprints among nearshore primary producers: Chlorophyta ( Ulva sp.), Ochrophyta (kelps), particulate organic matter (POM) and phytoplankton, and Rhodophyta. We ana lysed 135 samples from 14 genera collected in Alaska, California and Chile. Here we examine potential environmental and biochemical fac tors driving variation in amino acid δ 13 C values and associated mul tivariate isotopic fingerprints of nearshore marine autotrophs. We present δ 13 C data for 12 amino acids from 135 samples; this is the largest dataset of its kind to date. Our samples span four phyla/func tional groups of marine algae collected in Alaska, California and Chile, pure of In present data

The marine green alga Brilliantia kiribatiensis gen. et sp. nov. is described from samples collected from the coral reefs of the Southern Line Islands, Republic of Kiribati, Pacific Ocean. Phylogenetic analysis of sequences of the large- and small-subunit rDNA and the rDNA internal transcribed spacer region revealed that Brilliantia is a member of the Boodleaceae (Cladophorales), containing the genera Apjohnia, Boodlea, Cladophoropsis, Chamaedoris, Phyllodictyon, and Struvea. Within this clade it formed a distinct lineage, sister to Struvea elegans, but more distantly related to the bona fide Struvea species (including the type S. plumosa). Brilliantia differs from the other genera by having a very simple architecture forming upright, unbranched, single-celled filaments attached to the substratum by a rhizoidal mat. Cell division occurs by segregative cell division only at the onset of reproduction. Based on current sample collection, B. kiribatiensis seems to be largely restricted to the Southern Line Islands, although it was also observed on neighboring islands, including Orona Atoll in the Phoenix Islands of Kiribati, and the Rangiroa and Takapoto Atolls in the Tuamotus of French Polynesia. This discovery highlights the likeliness that there is still much biodiversity yet to be discovered from these remote and pristine reefs of the central Pacific.

Probabilistic maturation reaction norms (PMRNs) are commonly used to infer evolution of maturation age and size in wild fish stocks, but how well estimates from phenotypic data actually reflect underlying genotypes is debated. We used an eco-genetic model of a commercially harvested freshwater fish to simulate populations undergoing various levels of fisheries-induced evolution and density-dependent feedback and evaluated effects on the estimation of PMRNs. We estimated PMRNs from phenotypic data sampled from simulated populations (age, length, and maturation status of individuals), as is done for wild stocks, and compared estimates with the known maturation genotypes of individuals in the simulated population. PMRN estimates were robust to changes in the strength of density-dependent growth and high levels of fisheries-induced evolution. However, our ability to detect slower rates of evolution was limited, especially when individuals matured within a narrow range of ages. Furthermore, low numbers of immature or mature individuals within a given age class limited our ability to robustly estimate midpoints for more than one or two ages, despite our large sample sizes (n = 200 randomly sampled individuals of each age per year), highlighting a challenge with this approach. Nonetheless, this study suggests that the widely applied method of estimating PMRNs from readily available phenotypic data to detect underlying evolution of maturation schedule is robust to some key factors that vary in wild populations.

Emergent properties of ecosystems are community attributes, such as structure and function, that arise from connections and interactions (e.g., predator-prey, competition) among populations, species, or assemblages that, when viewed together, provide a holistic representation that is more than the sum of its individual parts. Climate change is altering emergent properties of aquatic ecosystems through component responses, a combination of shifts in species range, phenology, distribution, and productivity, which lead to novel ecosystems that have no historical analog. The reshuffling, restructuring, and rewiring of aquatic ecosystems due to climate impacts are of high concern for natural resource management and conservation as these changes can lead to species extinctions and reductions in ecosystem services. Overall, we found that substantial progress has been made to advance our understanding of how climate change is affecting emergent properties of aquatic ecosystems. However, responses are incredibly complex, and high uncertainty remains for how systems will reorganize and function over the coming decades. This cross-system perspective summarizes the state of knowledge of climate-driven emergent properties in aquatic habitats with case studies that highlight mechanisms of change, observed or anticipated outcomes, as well as insights into confounding non-climate effects, research tools, and management approaches to advance the field.

To better understand the ecology of coldwater fishes in urban-dominated landscapes, factors influencing seasonal brook trout (Salvelinus fontinalis) habitat use were assessed using backpack electrofishing surveys in three urban groundwater-fed streams in central Ontario. Generalised additive models revealed that yearling brook trout (<100 mm TL) were primarily influenced by water quality (stream temperature, conductivity), while older brook trout (>= 100 mm TL) were primarily influenced by stream morphology (water depth, undercut bank volume). Colder stream temperatures were preferred by yearlings in summer, whereas they occupied the warmest temperatures available in winter and spring. Yearlings were never found in sites with high stream conductivity (>= 900 mu s/cm), regardless of season, which may be attributed to poor water quality in stream sections with stormwater influence. Older brook trout were found mainly at intermediate pool depths in spring and summer, while there was a greater range of depths used during the spawning season. Undercut banks were important for older brook trout occupancy at all times of year. The protection of groundwater aquifers in urban watersheds is recommended to maintain optimal temperature regimes for the persistence and successful recruitment of native brook trout.

1. The effects of nutrient pollution on coral reef ecosystems are multifaceted. Numerous experiments have sought to identify the physiological effects of nutrient enrichment on reef-building corals, but the results have been variable and sensitive to choices of nutrient quantity, chemical composition and exposure duration. 2. To test the effects of chronic, ecologically relevant nutrient enrichment on coral growth and photophysiology, we conducted a 5-week continuous dosing experiment on two Hawaiian coral species, Porites compressa and Pocillopora acuta. We acclimated coral fragments to five nutrient concentrations (0.1-7 mu M NO3- and 0.06-2.24 mu M PO43-) with constant stoichiometry 2.5:1 nitrate to phosphate) bracketing in situ observations from reefs throughout the Pacific. 3. Nutrient enrichment linearly increased photophysiological performance of both species within 3 weeks. The effect of nutrients on P. acuta photochemical efficiency increased through time while a consistent response in P. compressa indicated acclimation to elevated nutrients within 5 weeks. Endosymbiont densities and total chlorophyll concentrations also increased proportionally with nutrient enrichment in P. acuta, but not in P. compressa, revealing contrasting patterns of host-symbiont acclimatization. 4. The two species also exhibited contrasting effects of nutrient enrichment on skeletal growth. Calcification was enhanced at low nutrient enrichment (1 mu M NO3-) in P. acuta, but comparable to the control at higher concentrations, whereas calcification was reduced in P. compressa (30%-35%) above 3 mu M NO3-. 5. Stable isotope analysis revealed species-specific nitrogen uptake dynamics in the coral-algal symbiosis. The endosymbionts of P. acuta exhibited increased nitrogen uptake (decreased delta N-15) and incorporation (19%-31% decrease in C:N ratios) across treatments. In contrast, P. compressa endosymbionts maintained constant delta N-15 values and low levels of nitrogen incorporation (9%-11% decrease in C:N ratios). The inability of P. acuta to regulate endosymbiont nutrient uptake may indicate an emerging destabilization in the coral-algal symbiosis under nutrient enrichment that could compromise resistance to additional environmental stressors. 6. Our results highlight species-specific differences in the coral-algal symbiosis, which influence responses to chronic nutrient enrichment. These findings showcase how symbioses can vary among closely related taxa and underscore the importance of considering how life-history traits modify species response to environmental change.

Inhibitory interneurons comprise a fraction of the total neurons in the visual thalamus but are essential for sharpening receptive field properties and improving contrast-gain of retinogeniculate transmission. During early development, these interneurons undergo long-range migration from germinal zones, a process regulated by the innervation of the visual thalamus by retinal ganglion cells. Here, using transcriptomic approaches, we identified a motogenic cue, fibroblast growth factor 15 (FGF15), whose expression in the visual thalamus is regulated by retinal input. Targeted deletion of functional FGF15 in mice led to a reduction in thalamic GABAergic interneurons similar to that observed in the absence of retinal input. This loss may be attributed, at least in part, to misrouting of interneurons into nonvisual thalamic nuclei. Unexpectedly, expression analysis revealed that FGF15 is generated by thalamic astrocytes and not retino-recipient neurons. Thus, these data show that retinal inputs signal through astrocytes to direct the long-range recruitment of interneurons into the visual thalamus.

In warmwater fishes, feeding during winter is often assumed to be negligible; however, there is growing evidence that juveniles will feed opportunistically even at cold temperatures. If fishes are able to effectively digest prey, then feeding during winter could supplement energy reserves and mitigate the risk of winter starvation. We use laboratory and pond experiments to determine whether feeding during winter can supplement energy reserves in a warmwater species. We compared juvenile Pumpkinseed (Lepomis gibbosus) from two cold-climate (native Canadian) and two warm-climate (non-native Spanish) populations raised in a common environment to determine whether winter feeding is more prevalent in populations that typically experience longer winters. Under simulated winter conditions, Pumpkinseed with access to prey readily fed and had greater lipid mass in spring than those without access to prey. Despite similar rates of consumption, winter feeding improved lipid mass to a greater extent in the Canadian populations, indicating that feeding benefitted the cold-climate populations more than the warm-climate populations. All populations of Pumpkinseed overwintering in outdoor ponds also fed regularly, with 88% of individuals collected mid-winter containing at least one prey item. The pattern of loss in energy reserves over time varied dramatically among populations suggesting that pond-specific environmental conditions were important in shaping how energy reserves were used. These results indicate that winter feeding may be more common in juvenile warmwater fishes than previously thought and that supplementation of energy reserves during winter should be taken into account when considering the factors influencing first year recruitment success.