Macroalgae exhibit diverse responses to human disturbances on coral reefs

Scientists and managers rely on indicator taxa such as coral and macroalgal cover to evaluate the effects of human disturbance on coral reefs, often assuming a universally positive relationship between local human disturbance and macroalgae. Despite evidence that macroalgae respond to local stressors in diverse ways, there have been few efforts to evaluate relationships between specific macroalgae taxa and local human-driven disturbance. Using genus-level monitoring data from 1205 sites in the Indian and Pacific Oceans, we assess whether macroalgae percent cover correlates with local human disturbance while accounting for factors that could obscure or confound relationships. Assessing macroalgae at genus level revealed that no genera were positively correlated with all human disturbance metrics. Instead, we found relationships between the division or genera of algae and specific human disturbances that were not detectable when pooling taxa into a single functional category, which is common to many analyses. The convention to use percent cover of macroalgae as an indication of local human disturbance therefore likely obscures signatures of local anthropogenic threats to reefs. Our limited understanding of relationships between human disturbance, macroalgae taxa, and their responses to human disturbances impedes the ability to diagnose and respond appropriately to these threats.

Coral reefs in the Gilbert Islands of Kiribati: Resistance, resilience, and recovery after more than a decade of multiple stressors

Coral reefs are increasingly affected by a combination of acute and chronic disturbances from climate change and local stressors. The coral reefs of the Republic of Kiribati’s Gilbert Islands are exposed to frequent heat stress caused by central-Pacific type El Niño events, and may provide a glimpse into the future of coral reefs in other parts of the world, where the frequency of heat stress events will likely increase due to climate change. Reefs in the Gilbert Islands experienced a series of acute disturbances over the past fifteen years, including mass coral bleaching in 2004–2005 and 2009–2010, and an outbreak of the corallivorous sea star Acanthaster cf solaris, or Crown-of-Thorns (CoTs), in 2014. The local chronic pressures including nutrient loading, sedimentation and fishing vary within the island chain, with highest pressures on the reefs in urbanized South Tarawa Atoll. In this study, we examine how recovery from acute disturbances differs across a gradient of human influence in neighboring Tarawa and Abaiang Atolls from 2012 through 2018. Benthic cover and size frequency data suggests that local coral communities have adjusted to the heat stress via shifts in the community composition to more temperature-tolerant taxa and individuals. In densely populated South Tarawa, we document a phase shift to the weedy and less bleaching-sensitive coral Porites rus, which accounted for 81% of all coral cover by 2018. By contrast, in less populated Abaiang, coral communities remained comparatively more diverse (with higher percentages of Pocillopora and the octocoral Heliopora) after the disturbances, but reefs had lower overall hard coral cover (18%) and were dominated by turf algae (41%). The CoTs outbreak caused a decline in the cover and mean size of massive Porites, the only taxa that was a ‘winner’ of the coral bleaching events in Abaiang. Although there are signs of recovery, the long-term trajectory of the benthic communities in Abaiang is not yet clear. We suggest three scenarios: they may remain in their current state (dominated by turf algae), undergo a phase shift to dominance by the macroalgae Halimeda, or recover to dominance by thermally tolerant hard coral genera. These findings provide a rare glimpse at the future of coral reefs around the world and the ways they may be affected by climate change, which may allow scientists to better predict how other reefs will respond to increasing heat stress events across gradients of local human disturbance.

The relationship between macroalgae taxa and human disturbance on central Pacific coral reefs

Climate change and human disturbance threatens coral reefs across the Pacific, yet there is little consensus on what characterizes a "healthy" reef. Benthic cover, particularly low coral cover and high macroalgae cover, are often used as an indicator of reef degradation, despite uncertainty about the typical algal community compositions associated with either near-pristine or damaged reefs. In this study, we examine differences in coral and algal community compositions and their response to human disturbance and past heat stress, by analysing 25 sites along a gradient of human disturbance in Majuro and Arno Atolls of the Republic of the Marshall Islands. Our results show that total macroalgae cover indicators of reef degradation may mask the influence of local human disturbance, with different taxa responding to disturbance differently. Identifying macroalgae to a lower taxonomic level (e.g. the genus level) is critical for a more accurate measure of Pacific coral reef health.

Treatment of negative symptoms in schizophrenia and schizoaffective disorder by selegiline augmentation of antipsychotic medication. A pilot study examining the role of dopamine

It has been suggested that schizophrenic negative symptoms may be manifestations of regionally deficient CNS dopaminergic activity. We sought to test this hypothesis by openly treating patients on chronic antipsychotic medication who showed prominent negative symptoms with low-dose selegiline (5 mg b.i.d.), a monoamine oxidase-B inhibitor that selectively enhances dopaminergic activity. Twenty-one patients meeting DSM-III-R criteria for chronic schizophrenia (N = 14) or schizoaffective disorder (N = 7) with prominent negative symptoms were studied. Subjects had been kept at their current antipsychotic and antiparkinsonian medication dose levels for at least a month before the study, which was continued unchanged throughout the trial. Over 6 weeks of selegiline treatment, a 34.7% reduction in negative symptoms was demonstrated on the Scale for the Assessment of Negative Symptoms. There were also reductions in depressive symptoms (21-item Hamilton Depression Scale dropped 36.8%) and extrapyramidal symptoms (Simpson-Angus Extrapyramidal Symptom Scale scores dropped 27.7%), but no change was observed in the severity of positive symptoms as measured by the Brief Psychiatric Rating Scale. Global clinical improvement was demonstrated, with mean Clinical Global Impressions Scale score rising 17.6%. These findings support the hypothesis that negative symptoms, as well as extrapyramidal symptoms and certain depressive symptoms, may be manifestations of regionally deficient dopaminergic activity.

Reassessment of blood donor selection criteria for United States travelers to malarious areas

In the United States (US), travelers who have had malaria or who have taken antimalarial chemoprophylaxis are deferred as blood donors for 3 years to prevent transfusion-transmitted malaria. To assess the impact of shortening this 3-year exclusion period, national malaria surveillance data from 1972 to 1988 were reviewed. The average annual rate of transfusion-transmitted malaria is 0.25 cases per million units of blood collected. Of 45 reported cases, 38 percent were caused by Plasmodium malariae, 29 percent by P. falciparum, 24 percent by P. vivax, and 9 percent by P. ovale. Thirty-two donors were implicated in 34 cases of transfusion-transmitted malaria. Of 30 implicated donors whose native country was identified, 23 (77%) were foreign nationals and 7 (23%) were from the US. In a review of all imported malaria cases by species and by interval between date of entry and onset of illness, 98 percent of P. falciparum, 86 percent of P. malariae, 76 percent of P. vivax, and 74 percent of P. ovale infections became symptomatic within 6 months of the patient's arrival in the US, regardless of the use of prophylaxis. Shortening to 6 months the donor exclusion period for US travelers to malarious areas would result in a minimum of 70,000 additional blood donors' being made available, with a maximum annual increase of 0.03 additional cases of transfusion-transmitted malaria. The potential benefit of bringing healthy travelers back into the donor pool after a shorter period of exclusion merits consideration by the blood banking industry.

Head-erect behavior among three preschool-aged children with cerebral palsy

This article presents the results of a multiple baseline design, across subjects, to assess the effect of vibratory stimulation on head-erect behavior in subjects who were prone. The subjects were three children with severe multiple handicaps whose mean age was 2 years 4 months and whose conditions included seizures and muscle tone disorders. Frequency of head lifts and cumulative duration of head-erect behavior were recorded during three-minute sessions with the subjects positioned prone on their forearms over a wedge. After baseline observations were recorded, vibration was applied to the paraspinal muscles of the neck and upper back for the first two minutes of each intervention session. In addition, electromyographic activity was recorded for a three-minute session at least once during both the baseline and intervention conditions. Results of the study demonstrated an increase in the cumulative duration of head-erect behavior for the three subjects and an accompanying increase in EMG activity during muscle vibration. The diversity of handicapping conditions (ie, seizures, hypertonia, and hypotonia) appeared to have no effect on the benefits received from muscle vibration for these subjects. Limitations of the study and implications for future research are discussed.