Sargassum events have been an increasingly influential phenomenon in the Caribbean region in recent years, with correspondingly growing attention from news and social media, the scientific community, and policy makers. To better understand the human effects of Sargassum events, an online survey of 633 community members, resource users, and government and NGO staff from across the Caribbean Basin was conducted in the summer and fall of 2021. Results indicated that Sargassum was widely regarded as a problem in all parts of the region, and that perceived event frequency, severity, and impacts varied by subregion. Impacts included economic harm from losses in tourism, recreation, and fisheries, as well as negative outcomes in public health, quality of life, and cultural practice. Management efforts are widespread, but there is a marked lack of confidence in government efforts to respond to Sargassum. These findings provide a regional baseline for social impacts of Sargassum, highlight vulnerable sectors, and identify sociocultural factors that managers should consider in the process of decision making with regard to this and other harmful macroalgal blooms.

Stakeholders' understanding of water quality influences how they approach water policy problems and their support for potential solutions. This study explores how resource policy in the United States accounts for different water quality meanings held by recreational users. In-person surveys were conducted along the shoreline in Rhode Island (USA) to examine how recreational users make sense of coastal water quality. Findings indicate that recreational users' understanding of water quality is constructed from an array of environmental conditions (e.g., chl a, phosphates) and attitudinal factors (e.g., perceived problems associated with sewage, algae, or trash), and the meanings ascribed to water quality extend beyond the biophysical indicators typically employed by water resource managers. Potential management strategies based on these findings include expanding current definitions of water quality and monitoring a broader suite of factors, conducting research that captures nuanced meanings of water quality held by different users, and developing outreach programs that clarify the potential impacts of water quality components on human health and well-being.

Invasive seaweeds have rapidly increased in global distribution and abundance in recent years, presenting significant threats to nearshore ecosystems. Developing characteristics diagnostic of potential macroalgal invasiveness is an important step in controlling their spread. Studies have identified photoacclimation, the ability of the photosynthetic apparatus to adjust to changes in light, as one important attribute in the success of several invasive terrestrial and marine plants; several studies indicate that the rate of photoacclimation plays a role in the differential success of invasive plants at the expense of natives. In this experiment, we compare two closely related species that occur in Hawaiian coastal waters with similar distribution, habitat, and morphology, the invasive Gracilaria salicornia, and the native G. coronopifolia. Samples were grown in outdoor culture, acclimated to one of two irradiance regimes, and reciprocally transplanted. Photoacclimation rates were assessed using in vivo spectrophotometry and PAM fluorometry. Results indicate that G. salicornia has remarkable tolerance to irradiance extremes and experiences rapid growth when transplanted from low to high photosynthetic photon flux density environments, and that differential rates of overall photoacclimation are insufficient to explain the relative success of these two plants. Photoacclimation is achieved via several complex processes that do not necessarily occur contemporaneously. Future researchers should be wary of assuming its completion based on single indicators.