Eckerd College is a private liberal arts college in St. Petersburg, Florida. Founded in 1958, part of the campus is waterfront and beach on Boca Ciega Bay. Because of its location, Eckerd is considered a "beach school" and has its own student volunteer maritime search and rescue team. Accredited by the Southern Association of Colleges and Schools, Eckerd is a member of the Annapolis and Oberlin groups of national liberal arts colleges.
Sedimentary phytopigments are indicators of organic matter quality and provide critical food for abyssal benthic communities, influencing their abundance, distribution, and diversity. As deep-sea mining emerges as a potential industry, studies addressing baseline conditions and effects of mining activities are crucial for understanding the resulting ecological risks and uncertainties. Here we examined the spatiotemporal variability of sedimentary phytopigments chlorophyll-a and pheophytin over a 3-year time series in the NORI-D contract area in the Clarion-Clipperton Zone of the central Pacific Ocean. Also investigated were the effects of a mining test on these parameters across a spectrum of disturbance zones including direct impact and varying degrees of sedimentation from the mining-generated plume. Baseline samples were collected in October-December 2020 and April-June 2021 from a collector test area (CTA) and preservation reference zone (PRZ), and from CTA in August-September 2022 immediately before a mining test in October 2022. Natural variations in sedimentary phytopigments were observed, with relative stability from 2020 to 2021, followed by a significant decrease in chlorophyll-a in the 2022 baseline samples, reflecting a temporal shift in organic matter quality. Chlorophyll-a concentrations were generally higher in the PRZ compared to the CTA, likely due to environmental heterogeneity. Baseline observations provided a reference for assessing changes in November-December 2022 following the mining test. Chlorophylla was diminished in the test-mining track, indicating sediment removal, while concentrations were enriched at a site 200 m away. These findings demonstrate the impact of deep-sea mining on sedimentary organic matter, with removal confined to the mining tracks and organic matter enrichment extending up to 200 m away. Although the abyssal seafloor is typically considered a stable environment, these results reflect fluctuations in organic matter input and quality, underscoring the importance of baseline time-series studies for distinguishing mining-induced changes from background fluctuations.
Coastal acidification is being exacerbated by terrestrial organic inputs, especially after high precipitation events. Florida’s rainy season coincides with stone crab (Menippe mercenaria) reproduction, and pH extremes could limit future harvests by reducing reproductive output. Populations that experience pH variability can serve as “natural laboratories” for estimating the tolerance of a species to coastal acidification. Here, we conducted a series of experiments to determine if ovigerous stone crabs conditioned in more variable pH habitats (seagrass) would result in faster embryonic development, greater hatching success, and higher larval survival relative to crabs conditioned in habitats with lower pH variability (sandy habitats). After field conditioning, crabs were transported to the laboratory and randomly acclimated to either a control pH (pH = 7.90) or a reduced pH condition (pH = 7.60) until larval release. The rate of embryo development was slower in the laboratory reduced pH treatment, however, there were no observable field condition effects on embryo development rate. Crabs conditioned in the more pH variable seagrass habitat did have greater hatching success and higher larval survival than crabs in less pH variable sandy habitats; however, larval survival was low across all treatments. These results suggest that the pH variability experienced in seagrass habitats during brooding may serve as a mechanism for stone crabs to acclimatize to extremes in seawater pH.
The deep sea contains a wealth of potential mineral resources, many of which are being investigated for commercial exploitation. Exploration and technical tests started in the late 1970s with an initial focus on polymetallic nodules from an abyssal region in the eastern Pacific Ocean called the Clarion-Clipperton Zone (CCZ). More recently, exploration has commenced at seafloor massive sulphides (formed by hydrothermal vents) and seamounts (for cobalt-rich crusts). Here we review the many decades of environmental research in these areas with a focus on the biodiversity baseline and the results from experimental mining or disturbance tests. Data from the CCZ have revealed that the seafloor is biodiverse, albeit at low biomass. For nodule mining, geophysical and biological impacts are persistent over at least multiple decades, although some dominant animal groups show successional recolonisation. By contrast, exploration for minerals at sulphide deposits and seamounts has been quite limited, empirical data on recovery timescales are lacking and these systems are likely to respond differently to disturbance. Deep-sea mining in any habitat could potentially generate plumes from ore dewatering which may affect pelagic ecosystems depending on the technology used. For all types of deep-sea mining, we distinguish ecological resilience and recovery from the risk of biodiversity loss (species extinction). Taxonomic data based on collections are critical to this debate; for abyssal fauna we can only currently hypothesise species ranges based on habitat availability. For vents, and to some degree seamounts, there is clear evidence that biodiversity loss from deep-sea mining is likely. If these sites were to be classified as areas of ‘high biodiversity importance' under the Convention on Biological Diversity, deep-sea mining at them would not be scientifically compatible with existing policy.
Understanding the geographic distribution of genetic diversity of imperiled species across all life history stages, and identifying the factors that shape those distributions, are key to maintaining long-term genetic diversity and the health of populations. This knowledge is particularly important for highly mobile marine organisms, whose extensive movements can obscure patterns of population structure. We substantially expand the genetic dataset for the critically endangered hawksbill turtle, Eretmochelys imbricata, in the West Atlantic, focusing on the southwest Caribbean. Our dataset comprises nearly 3,000 mtDNA control region sequences (740 bp) assigned to 60 haplotypes: 41 found in rookeries and 47 in foraging grounds, including 17 orphan haplotypes. The Panama metapopulation represents a major center of genetic diversity for hawksbills, with one of the highest recorded diversity values for the species (h = 0.749, π = 0.00782), nine endemic haplotypes, and four additional haplotypes that are endemic to the Southwest Caribbean. Rarefaction analyses indicate that a sample size of at least 100 is necessary to reveal true haplotype richness at most rookeries. Many-to-many mixed stock analyses, which incorporated rookery size and distance priors for 19 rookeries and 15 developmental foraging grounds, suggest that hatchlings from rookeries in the southwest Caribbean are distributed among multiple, widely-spaced foraging grounds across the West Atlantic. These results support a groups-to-soups analogy, in which genetic variability across foraging grounds represents a continuum of genetic diversity that can best be explained by a “current conveyor” model. The dataset shows that philopatry in hawksbills is not absolute, resulting in true biological dispersal and geneflow on local, regional, and ocean-basin scales, likely facilitated by dispersion during the epipelagic stage. The important contribution of oceanographic features to genetic variation at rookeries and foraging grounds is corroborated, as is the concept of oceanographic “dispersal shadows” that limit geneflow between rookeries. This study reinforces the assertion that all range states share responsibility for the recovery of the hawksbill, because foraging grounds, that are often at distant locations, are the source of future generations of reproductive adults. We also document significant movement by hawksbills between regional management units (RMUs) 29 and 30 in the West Atlantic. The Spanish version of the Abstract is available in Supplementary File 1.
