Story Grammar Analyses Capture Discourse Improvement in the First 2 Years Following a Severe Traumatic Brain Injury.

PURPOSE: Narration within a story grammar framework requires speakers to organize characters and events logically. Despite abundant research characterizing narrative deficits following a traumatic brain injury (TBI), the evolution of narrative story grammar over the first 2 years post-TBI has rarely been explored. This study analyzed story grammar in complex narratives of adults with and without severe TBI to (a) examine between-group differences and (b) investigate longitudinal changes over the first 2 years post-TBI. METHOD: Story grammar analyses of Cinderella narratives from 57 participants with TBI and 57 participants with no brain injury yielded measures of productivity (total number of episodes, total number of story grammar elements), elaboration (total number of elaborated-complete episodes, mean number of episodic elements per episode), and completeness (total number of incomplete episodes). Mann-Whitney U tests compared measures across groups; generalized estimating equation (GEE) models identified predictors of change, including recovery time (3, 6, 9, 12, and 24 months post-TBI) and demographic/injury-related characteristics. RESULTS: Between-group differences were statistically significant for all productivity and elaboration measures at 3, 6, and 9 months post-TBI; one productivity measure and one elaboration measure at 12 months; and none of the measures at 24 months. GEE models showed significant improvements in all productivity and elaboration measures over the first 24 months post-TBI, with educational attainment and duration of posttraumatic amnesia affecting recovery. Incomplete episodes only showed between-group differences at 12 months and did not capture recovery. CONCLUSION: Productivity and elaboration are key story grammar variables that (a) differentiate complex narration in individuals with and without severe TBI and (b) capture narrative improvements over the first 2 years post-TBI. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.25148999.

Seasonal Variability in Calorimetric Energy Content of Two Caribbean Mesophotic Corals.

Energetic responses of zooxanthellate reef corals along depth gradients have relevance to the refugia potential of mesophotic coral ecosystems (MCEs). Previous observations suggested that MCEs in the Caribbean are thermally buffered during the warmest parts of the year and occur within or just below the chlorophyll maximum, suggesting abundant trophic resources. However, it is not known if mesophotic corals can maintain constant energy needs throughout the year with changing environmental and biological conditions. The energetic content of tissues from the stony coral species Orbicella faveolata and Agaricia lamarcki was measured on the southern insular shelf of St. Thomas, US Virgin Islands (USVI), using micro-bomb calorimetry. Three sites for each species, at depths of 6m, 25m, 38m and 63m, were selected to capture energetic differences across the major vertical range extent of both species in the USVI-and sampled over five periods from April 2013 to April 2014. Mesophotic colonies of O. faveolata exhibited a significant reduction in energetic content during the month of September 2013 compared to mid-depth and shallow colonies (p = 0.032), whereas A. lamarcki experienced similar energetic variability, but with a significant reduction in energy content that occurred in July 2013 for colonies at sites deeper than 25m (p = 0.014). The results of calorimetric analyses indicate that O. faveolata may be at risk during late summer stress events, possibly due to the timing of reproductive activities. The low-point of A. lamarcki energy content, which may also coincide with reproduction, occurs prior to seasonal stress events, indicating contrasting, species-specific responses to environmental variability on MCEs.

Caribbean mesophotic coral ecosystems are unlikely climate change refugia.

Deeper coral reefs experience reduced temperatures and light and are often shielded from localized anthropogenic stressors such as pollution and fishing. The deep reef refugia hypothesis posits that light-dependent stony coral species at deeper depths are buffered from thermal stress and will avoid bleaching-related mass mortalities caused by increasing sea surface temperatures under climate change. This hypothesis has not been tested because data collection on deeper coral reefs is difficult. Here we show that deeper (mesophotic) reefs, 30-75 m depth, in the Caribbean are not refugia because they have lower bleaching threshold temperatures than shallow reefs. Over two thermal stress events, mesophotic reef bleaching was driven by a bleaching threshold that declines 0.26 °C every +10 m depth. Thus, the main premise of the deep reef refugia hypothesis that cooler environments are protective is incorrect; any increase in temperatures above the local mean warmest conditions can lead to thermal stress and bleaching. Thus, relatively cooler temperatures can no longer be considered a de facto refugium for corals and it is likely that many deeper coral reefs are as vulnerable to climate change as shallow water reefs.

Fertile fathoms: Deep reproductive refugia for threatened shallow corals.

The persistence of natural metapopulations may depend on subpopulations that exist at the edges of species ranges, removed from anthropogenic stress. Mesophotic coral ecosystems (30-150 m) are buffered from disturbance by depth and distance, and are potentially massive reservoirs of coral diversity and fecundity; yet we know little about the reproductive capabilities of their constituent species and the potential for these marginal environments to influence patterns of coral reef persistence. We investigated the reproductive performance of the threatened depth-generalist coral Orbicella faveolata over the extent of its vertical range to assess mesophotic contributions to regional larval pools. Over equal habitat area, mesophotic coral populations were found to produce over an order of magnitude more eggs than nearby shallow populations. Positive changes with depth in both population abundance and polyp fecundity contributed to this discrepancy. Relative larval pool contributions of deeper living corals will likely increase as shallow habitats further degrade due to climate change and local habitat degradation. This is a compelling example of the potential for marginal habitat to be critical to metapopulation persistence as reproductive refugia.

A depth refugium from catastrophic coral bleaching prevents regional extinction.

Species intolerant of changing climate might avoid extinction within refugia buffered from extreme conditions. Refugia have been observed in the fossil record but are not well documented or understood on ecological time scales. Using a 37-year record from the eastern Pacific across the two most severe El Niño events on record (1982-1983 and 1997 1998) we show how an exceptionally thermally sensitive reef-building hydrocoral, Millepora intricata, twice survived catastrophic bleaching in a deeper-water refuge (> 11 m depth). During both events, M. intricata was extirpated across its range in shallow water, but showed recovery within several years, while two other hydrocorals without deep-water populations were driven to regional extinction. Evidence from the subfossil record in the same area showed shallow-water persistence of abundant M. intricata populations from 5000 years ago, through severe El Niño-Southern Oscillation cycles, suggesting a potential depth refugium on a millennial timescale. Our data confirm the deep refuge hypothesis for corals under thermal stress.