Andrew Sweetman

Scottish Association for Marine Science (SAMS)

Holothurians are the dominant megabenthic deposit feeders in the Peru Basin (SE Pacific) and feed to various degrees of selectivity on a heterogenous pool of sedimentary detritus, but drivers of feeding selectivity and diet preferences for most holothurian species are unknown. This study reconstructs the diets of 13 holothurian species of the order...

The deep pelagic ocean is increasingly subjected to human-induced environmental change. While pelagic animals provide important ecosystem functions including climate regulation, species-specific responses to stressors remain poorly documented. Here, we investigate the effects of simulated ocean warming and sediment plumes on the cosmopolitan deep-s...

Ocean ecosystems are at the forefront of the climate and biodiversity crises, yet we lack a unified approach to assess their state and inform sustainable policies. This blueprint is designed around research capabilities and cross-sectoral partnerships. We highlight priorities including integrating basin-scale observation, modelling and genomic appr...

Abyssal plain communities rely on the overlying water column for a settling flux of organic matter. The origin and rate of this flux as well as the controls on its fine-scale spatial distribution following seafloor settlement are largely unquantified. This is particularly true across regions where anthropogenically-induced seafloor disturbance has...

Large, well-developed and flourishing reefs dominated by the cold-water coral Desmophyllum pertusum have recently been discovered along the Angola margin in the southeastern Atlantic Ocean living under very low oxygen concentrations (0.6–1.5 mL L− 1). This study assessed the respiration rates of this coral in a short-term (10 days) aquarium experim...

Ocean ecosystems are at the forefront of the climate and biodiversity crises, yet we lack a unified approach to assess their state and inform sustainable policies. This blueprint is designed around research capabilities and cross-sectoral partnerships. We highlight priorities including integrating basin-scale observation, modelling and genomic appr...

The abyssal seafloor (3500–6000m) remains largely unexplored but with deep-sea mining imminent, anthropogenic impacts may soon reach abyssal communities. Thus, there is a growing need for baseline studies of biodiversity, ecosystem functioning, and connectivity in both potential mining and no-mining areas across the Clarion-Clipperton Zone (CCZ), a...

Mangrove forests possess multiple functions for the environment and society through their valuable ecosystem services. Along with this, the mangrove forests have large and diverse social values, in combination contributing to the health and wellbeing of the surrounding communities. This study aims (i) to assess the benefits of mangrove forests and...

Deep-sea benthic communities depend on food that reaches the seafloor from the overlying water column as well as from in-situ autotrophic production. Sinking carcasses (food falls) from jellyfish and squid contribute to this nutrient flux, but natural medium-sized food falls are rarely observed. Consequently, little is known about scavenging commun...

Calcifying plankton in the upper ocean produce calcium carbonate (CaCO3) shells that sink to the seafloor after death resulting in the vertical transport of inorganic carbon in shells and organic carbon in carcasses. In situ observations of pelagic detritus on the abyssal plain are very scarce. Carcasses are rapidly scavenged and shells may dissolv...

Cold-water coral (CWC) habitats dwell on continental shelves, slopes, seamounts, and ridge systems around the world’s oceans from 50 to 4000 m depth, providing heterogeneous habitats which support a myriad of associated fauna. These highly diverse ecosystems are threatened by human stressors such as fishing activities, gas and oil exploitation, and...

As biodiversity loss accelerates globally, understanding environmental influence over biodiversity-ecosystem functioning (BEF) relationships becomes crucial for ecosystem management. Theory suggests that resource supply affects the shape of BEF relationships, but this awaits detailed investigation in marine ecosystems. Here, we use deep-sea chemosy...

Jellyfish carrion is an important carbon source to the benthic ecosystem that is expected to increase in some regions in the future, but its potential impact on sediment biochemical processes is not fully understood. Benthic foraminifera play important carbon processing roles in marine ecosystems, but little is known about how they process carbon w...

The Clarion Clipperton Zone (CCZ) is a vast area of the central Pacific Ocean where the abyssal seabed is a focus for future polymetallic nodule mining. Broad-scale environmental gradients occur east-to-west across the CCZ seabed, including organic matter supply and nodule abundance, factors that influence benthic faunal community structure and fun...

Benthic megafauna (organisms large enough to be visible on seabed photographs) are regarded as important for carbon cycling in benthic habitats. They are a food source for many predators like fish and marine mammals and may stimulate carbon mineralization in sediment by bioturbation. However, few studies address these basic characteristics of megab...

Sediment profiling imaging (SPI) is a versatile and widely used method to visually assess the quality of seafloor habitats (e.g., around fish farms and oil and gas rigs) and has been developed and used by both academics and consultancy companies over the last 50 years. Previous research has shown that inserting the flat viewport of an SPI camera in...

Food availability in fjords is unusual among deep-sea environments (defined here as systems below 200 m) due to the increased availability of nutritional sources that are comparatively rare in the open sea, such as influxes of macrophytodetritus and terrestrial organic matter. In open waters, these deep-sea ‘organic falls’ have been shown to increa...

The sea floor represents the largest solid ecosystem on our Planet. This heterogeneous realm consists of many different features shaped by millions of years of geological and chemical events, and biological and environmental evolution. “Extreme” benthic environments, defined as having abiotic conditions that demand organisms and resident communitie...

Fjordic systems in temperate and Arctic regions often feature extensive kelp forests at their shallow coastal margins as well as extensive terrestrial forests. Detrital export from these shallow-water and terrestrial ecosystems is an important source of carbon for deep-sea communities in the form of kelp and wood falls. Benthic landers with experim...

In high latitude coastal regions, benthic scavenger communities are largely composed of invertebrates that play a key role in the cycling of organic matter. Factors including temperature and depth can structure Arctic and Subarctic fjord benthic communities, but the response of scavenging communities to these factors is poorly known. To address thi...

In the deep sea, benthic communities largely depend on organic material from the overlying water column for food. The remains of organisms on the seafloor (food falls) create areas of organic enrichment that attract scavengers. The scavenging rates and communities of food falls of medium-sized squid, fish and jellyfish (1-100 cm) are poorly known....

The sea floor represents the largest ecosystem on our Planet. This heterogeneous realm consists of many different features shaped by millions of years of geological and chemical events, and biological and environmental evolution. "Extreme" benthic environments cover more than 50% of the Earth's surface and offer many opportunities for investigating...

The calving of A‐68, the 5,800‐km², 1‐trillion‐ton iceberg shed from the Larsen C Ice Shelf in July 2017, is one of over 10 significant ice‐shelf loss events in the past few decades resulting from rapid warming around the Antarctic Peninsula. The rapid thinning, retreat, and collapse of ice shelves along the Antarctic Peninsula are harbingers of wa...

Due to the predicted future demand for critical metals, abyssal plains covered with polymetallic nodules are currently being prospected for deep-seabed mining. Deep-seabed mining will lead to significant sediment disturbance over large spatial scales and for extended periods of time. The environmental impact of a small-scale sediment disturbance wa...

Sustainable development of the salmon farming industry requires knowledge of the biogeochemical impacts of fish farm emissions. To investigate the spatial and temporal scales of farm impacts on the water column and benthic biogeochemistry, we coupled the C-N-P-Si-O-S-Mn-Fe transformation model BROM with a 2-dimensional benthic-pelagic transport mod...

Fine-grain, waste rock (or tailings) produced during mining processes are the main waste product following the extraction of valuable minerals and metals from ores. The proximity of mineral resources to coastal regions in some countries has meant that the organically inert mine tailings are often deposited into the marine environment as a submarine...

Scientific misconceptions are likely leading to miscalculations of the environmental impacts of deep-seabed mining. These result from underestimating mining footprints relative to habitats targeted and poor understanding of the sensitivity, biodiversity, and dynamics of deep-sea ecosystems. Addressing these misconceptions and knowledge gaps is need...

Climate change manifestation in the ocean, through warming, oxygen loss, increasing acidification and changing particulate organic carbon flux (one metric of altered food supplies), is projected to affect most deep‐ocean ecosystems concomitantly with increasing direct human disturbance. Climate drivers will alter deep‐sea biodiversity and associate...

In the Clarion-Clipperton Zone (CCZ) in the north-eastern Pacific Ocean ca. 30 billion tonnes of polymetallic nodules, rich in metals critical for frontier technologies, lay on the sediment surface over an area of 4–5 million square kilometres. For this reason, there is accelerating interest in deep-sea mineral mining in the CCZ. Few data exist con...

The deep sea plays a critical role in global climate regulation through uptake and storage of heat and carbon dioxide. However, this regulating service causes warming, acidification and deoxygenation of deep waters, leading to decreased food availability at the seafloor. These changes and their projections are likely to affect productivity, biodive...

The sediment profile imaging (SPI) camera system is widely used to evaluate the health of benthic communities particularly those impacted of anthropogenic stressors. Although it is a commercially and scientifically used tool, the influence of the SPI camera penetrating the sediment and the reliability of the data have not been studied yet. While p...

Mining impacts will affect local populations to different degrees. Impacts range from removal of habitats and possible energy sources to pollution and smaller-scale alterations in local habitats that, depending on the degree of disturbance, can lead to extinction of local communities. While there is a shortage or even lack of studies investigating...

The cycling of carbon (C) by benthic organisms is a key ecosystem function in the deep sea. Pulse‐chase experiments are designed to quantify this process, yet few studies have been carried out using abyssal (3500–6000 m) sediments and only a handful of studies have been undertaken in situ. We undertook eight in situ pulse‐chase experiments in three...

Mining polymetallic nodules on abyssal plains will have adverse impacts on deep-sea ecosystems, but it is largely unknown whether the impacted ecosystem will recover, and if so at what rate. In 1989 the "DISturbance and reCOLonization" (DISCOL) experiment was conducted in the Peru Basin where the seafloor was disturbed with a plough harrow construc...

Future deep-sea mining for polymetallic nodules in abyssal plains will negatively impact the benthic ecosystem, but it is largely unclear whether this ecosystem will be able to recover from mining disturbance and if so, to what extent and at what timescale. During the DISturbance and reCOLonization (DISCOL) experiment, a total of 22 % of the seaflo...

Recent analyses of metabolic rates in fishes, echinoderms, crustaceans and cephalopods have concluded that bathymetric declines in temperature- and mass-normalized metabolic rate do not result from resource-limitation (e.g. oxygen or food/chemical energy), decreasing temperature or increasing hydrostatic pressure. Instead, based on contrasting bath...

This discussion paper is a preprint. It is a manuscript under review for the journal Biogeosciences (BG) Stratmann, T., Lins, L., Purser, A., Marcon, Y., Rodrigues, C. F., Ravara, A., Cunha, M. R., Simon-Lledó, E., Jones, D. O. B., Sweetman, A. K., Köser, K., and van Oevelen, D.: Faunal carbon flows in the abyssal plain food web of the Peru Basin h...

The potential harvest of polymetallic nodules will heavily impact the abyssal, soft sediment ecosystem by removing sediment, hard substrate, and associated fauna inside mined areas. It is therefore important to know whether the ecosystem can recover from this disturbance and if so at which rate. The first objective of this study was to measure reco...

Gelatinous zooplankton populations have increased in some regions, specifically Norwegian fjords, which has likely increased the occurrence of dead jellyfish aggregations on the seafloor (jelly-falls). The importance of scavengers in the redistribution of organic material from jelly-falls and their biogeochemical influence on the benthic environmen...

Here we provide empirical evidence of the presence of an energetic pathway between jellyfish and a commercially important invertebrate species. Evidence of scavenging on jellyfish carcasses by the Norway lobster (Nephrops norvegicus) was captured during two deployments of an underwater camera system to 250-287 m depth in Sognefjorden, western Norwa...

The extraction of minerals from land-based mines necessitates the disposal of large amounts of mine tailings. Dumping and storage of tailings into the marine environment, such as fjords, is currently being performed without knowing the potential ecological consequences. This study investigated the effect of short-term exposure to different depositi...

Shipwrecks can be considered island-like habitats on the seafloor. We investigated the fauna of 8 historical shipwrecks off the US east coast to assess whether species distribution patterns on the shipwrecks fit models from classical island theory. Invertebrates on the shipwrecks included both sessile (sponges, anemones, hydroids) and motile (crust...

The deep sea encompasses the largest ecosystems on Earth. Although poorly known, deep seafloor ecosystems provide services that are vitally important to the entire ocean and biosphere. Rising atmospheric greenhouse gases are bringing about significant changes in the environmental properties of the ocean realm in terms of water column oxygenation, t...

Commercial-scale mining for polymetallic nodules could have a major impact on the deep-sea environment, but the effects of these mining activities on deep-sea ecosystems are very poorly known. The first commercial test mining for polymetallic nodules was carried out in 1970. Since then a number of small-scale commercial test mining or scientific di...

Table of cruises related to simulated mining on the deep seafloor. (XLSX)

Data used in meta-analysis. See headings tab for more details. (XLSX)

PRISMA checklist. (DOC)

The industrialization of the deep sea is expanding worldwide. Expanding oil and gas exploration activities in the absence of sufficient baseline data in these ecosystems has made environmental management challenging. Here, we review the types of activities that are associated with global offshore oil and gas development in water depths over 200 m,...

Ch. 20: Coastal, Riverine, and Atmospheric Inputs from Land, 93 p. Allan Simcock et.al. 2016 (Maruf Hossain -co-author )

Jellyfish blooms have increased in magnitude in several locations around the world, including in fjords. While the factors that promote jellyfish blooms and the impacts of live blooms on marine ecosystems are often investigated, the post-bloom effects from the sinking and accumulation of dead jellyfish at the seafloor remain poorly known. Here, we...

Stones released by melting icebergs are called dropstones, and these stones constitute island-like hard-bottom habitats at high latitudes. In 2012, dropstone megafauna in the HAUSGARTEN observatory in the Fram Strait was sampled photographically. We tested the hypothesis that dropstones would have the same species distribution patterns as terrestri...