This review examines environmental factors affecting potentially toxic elements (PTEs) in coastal waters with the goal of proposing ways to enhance the use of benthic foraminifers as bioindicators of such pollution. Pollution of coastal systems by PTEs, often referred to as heavy metals, is a major concern for scientists, resource managers, and regulatory agencies. Bioavailability, uptake rates, speciation, clay mineralogy, pH, complexation, and other factors control the behavior of PTEs in marine systems, especially in estuaries. While breakthrough work has examined incorporation and assimilation of metals into marine macroinvertebrates, similar research on marine protists is still in the developmental stage. Many studies assume or conclude that foraminiferal assemblages and the frequency of deformed tests are first-line indicators of pollution, but others present confounding results. Understanding the complex geochemistries of PTEs, coastal waters, and sediments is critical to the design and interpretation of meaningful studies. Applications of foraminifers as bioindicators require strong scientific models based on both field and laboratory experiments and which specifically examine the influence of PTEs and other pollutants at community, assemblage, population, individual, and gene-expression levels. Genomic studies of key foraminiferal taxa with strong potential as bioindicators are critically needed as a basis for studies of gene expression indicating exposure to specific stressors. Though major challenges exist to fully realizing the potential for application of foraminifers as environmental indicators, their global importance in the past and present argues strongly for further development of these promising tools.

IODP Expedition 340 successfully drilled a series of sites offshore Montserrat, Martinique and Dominica in the Lesser Antilles from March to April 2012. These are among the few drill sites gathered around volcanic islands, and the first scientific drilling of large and likely tsunamigenic volcanic island‐arc landslide deposits. These cores provide evidence and tests of previous hypotheses for the composition and origin of those deposits. Sites U1394, U1399, and U1400 that penetrated landslide deposits recovered exclusively seafloor sediment, comprising mainly turbidites and hemipelagic deposits, and lacked debris avalanche deposits. This supports the concepts that i/ volcanic debris avalanches tend to stop at the slope break, and ii/ widespread and voluminous failures of preexisting low‐gradient seafloor sediment can be triggered by initial emplacement of material from the volcano. Offshore Martinique (U1399 and 1400), the landslide deposits comprised blocks of parallel strata that were tilted or microfaulted, sometimes separated by intervals of homogenized sediment (intense shearing), while Site U1394 offshore Montserrat penetrated a flat‐lying block of intact strata. The most likely mechanism for generating these large‐scale seafloor sediment failures appears to be propagation of a decollement from proximal areas loaded and incised by a volcanic debris avalanche. These results have implications for the magnitude of tsunami generation. Under some conditions, volcanic island landslide deposits composed of mainly seafloor sediment will tend to form smaller magnitude tsunamis than equivalent volumes of subaerial block‐rich mass flows rapidly entering water. Expedition 340 also successfully drilled sites to access the undisturbed record of eruption fallout layers intercalated with marine sediment which provide an outstanding high‐resolution data set to analyze eruption and landslides cycles, improve understanding of magmatic evolution as well as offshore sedimentation processes.

Pollution from untreated human sewage is one of several environmental concerns in the coastal waters of Belize. This study utilized distributions of fecal sterols and foraminiferal assemblages to determine if human sewage is affecting the coral reef system off the coast of Caye Caulker, Belize. A total of 125 sediment samples were collected from which fecal sterol concentrations (coprostanol, cholestanol and cholesterol) and diagnostic stanol ratios, sediment texture (% mud), and foraminiferal ecological indices, including species richness, density, and diversity, and the FORAM Index (FI), were assessed. Elevated concentrations of coprostanol were primarily found inshore, with 20 samples exceeding 100 ng/g. The two stanol ratios, evaluated together, confirmed presence of human sewage at 17 sites. Foraminiferal assemblages were dominated by Quinqueloculina, Trochulina, Archaias and Asterigerina. Predominance of sand-sized sediments and the prevalence of Trochulina rosea and Asterigerina carinata reflected the active hydrodynamic regime, particularly on the eastern side of the caye. While the FI values overall indicated that water quality is conducive to reef growth and recovery, data from 37 samples indicated that the area is experiencing environmental change, especially on the southwestern side. Significant positive correlations were found between coprostanol and both foraminiferal density and diversity, while coprostanol and FI were negatively correlated. These results indicate that human sewage is inducing nutrification, which may be promoting reported increases in macroalgal abundances throughout Belize, though the active wave and current regimes are limiting the impacts on the eastern, Caribbean-facing side of Caye Caulker.