Linking the scientific knowledge on marine frontal systems with ecosystem services

A cumulative impact assessment on the marine capacity to supply ecosystem services

Ecosystem services link the status of biodiversity and its functioning to societal goods and benefits contributing to human wellbeing. As such, they can play a key role in preserving the environment and managing natural resources and ecosystems to conserve nature's contributions to people. Identification of the main threats acting on the natural environment, and how these may impact its capacity to supply ecosystem services, is fundamental to the maintenance of these services. To that end, we present a novel approach based on a cumulative impacts assessment that 1) covers all relevant human activities and their pressures, 2) links impacts to the biotic groups that make up biodiversity and 3) provides an estimation of the Service Supply Potential based on the functioning of these biotic groups. Key proxy metrics to estimate this Service Supply Potential were identified from a literature review and quantified using a food web model (Ecopath with Ecosim). In addition to this quantitative information, the assessment of the capacity to supply ecosystem services was supplemented with expert judgement-based information to reflect the societal preferences that drive the allocation of human capital and turn these services into societal goods and benefits. As a proof of concept, the method was applied to the North Sea ecosystem. Results showed that, overall, the capacity of the North Sea to supply Cultural ecosystem services was most threatened, with an average potential decline of 50 % compared to an undisturbed situation. This was followed by the Provisioning ecosystem services with 46 % and the Regulation & Maintenance with 38 %. The main anthropogenic threats (excluding climate change) to the North Sea capacity to supply ecosystem services come primarily from fishing contributing to 51 % of the overall threat. Of the remaining 18 sectoral activities another 23 % was contributed by mining, non-renewable energy, tourism, and agriculture.

Frontal processes as drivers of floating marine debris in coastal areas

The influence of floating marine debris (FMD) on coastal and marine communities and ecosystems is undeniable, and attention is increasingly focused on ecologically and biologically important coastal areas. To protect marine life and valuable resources from FMD pollution, identifying FMD accumulation zones is recognized as a priority. One of the coastal ocean processes found governing the distribution of FMD is water convergence (frontal zones). These fronts are driven by various oceanographical factors. To date, the transport and accumulation of FMD in relation to fronts in coastal areas is poorly understood. To address this knowledge gap, we reviewed various types of ocean fronts as well as FMD accumulation along frontal zones in coastal areas defined as the region between the coastline and the shelf break. Frontogenesis (physical processes related to frontal formation) were reviewed alongside studies on FMD accumulation in frontal zones to identify physical factors that drive the pathways and accumulation in these areas. This review will contribute to our understanding of accumulation hotspots of FMD within ocean fronts and identify gaps for further research on developing a proxy for FMD hotspot identification in ecologically important coastal areas.

Global mapping and evolution of persistent fronts in Large Marine Ecosystems over the past 40 years

Ocean fronts, characterized by narrow zones with sharp changes in water properties, are vital hotspots for ecosystem services and key regulators of regional and global climates. Global change is reshaping the distribution of material and energy in the ocean; however, it remains unclear how fronts have varied in the last few decades. Here, we present a global, fine-scale digital atlas of persistent fronts around Large Marine Ecosystems and demonstrate significant global increases in both their occurrence and intensity. In subtropical regions (around boundary currents and upwelling systems) and polar regions, persistent frontal occurrence and intensity are rapidly increasing, while in tropical regions, they remain stable or slightly decrease. These enhancements may be respectively related to changes in boundary currents, upwelling, and sea ice retreat. This spatially heterogeneous trend holds important implications for the redistribution of front-related ecosystem services and air-sea interactions but has not been captured by representative high-resolution climate projections models or observation-assimilated ocean models.

Distribution, bioavailability, and ecological risk assessment of potentially toxic heavy metals in El-Burullus Lake sediments, Egypt

El-Burullus Lake is the second largest coastal lagoon in Egypt in addition to its connection to the Mediterranean Sea. In this study, geochemical fractionations of heavy metals (Fe, Pb, Cd, Cu, Cr and Zn) were investigated after the great efforts made to rehabilitate and restore the lake by the Egyptian Government. The results indicated that F4 (residual fraction) was the dominant fraction for all studied metals followed by F3 (oxidizable fraction). That means the majority of studied metals source in the lake is lithogenic. Contamination by each individual heavy metal or multi elements was low according to individual contamination factor (ICF) and global contamination factor (GCF). Risk assessment code (RAC) classification showed that Cd and Cu exhibited low risk, Zn was of moderate risk, whereas, other metals are safe. The toxicity calculated by toxic risk index (TRI) indicating that no toxic risk was expected in the Lake.

Risk assessment and spatio-temporal distribution of dissolved trace metals in Swarna, Sharavati and Kali estuaries, South-West Coast of India

Trace metals act as a limiting nutrient and prerequisite for primary productivity in marine environments. The distribution of metals in dissolved phase along the salinity gradients of Swarna, Sharavati and Kali estuaries in southwestern India, during post and pre-monsoon seasons, were studied. We have investigated the behaviour of trace metals in the estuarine environment and their extent of impact on human health and ecosystem. The study revealed, non-conservative behaviour of dissolved Mn, Fe, Ni, Cd and Co in the estuaries. Whereas Cu behaved non-conservatively in post-monsoon and conservatively in pre-monsoon seasons. Risk assessment studies revealed that higher chronic daily intake (CDI) in humans, through dermal pathway, in Swarna and Sharavati estuaries during post-monsoon, whereas it was during pre-monsoon season in the Kali estuary. Hazard Index values for the studied metals in adults and children are below risk thresholds, though children are more prone to health risk through the dermal pathway.

Comprehensive Ecological Risk Assessment of Heavy Metals Based on Species Sensitivity Distribution in Aquatic of Coastal Areas in Hong Kong

In recent decades, the ecological environment of some coastal areas in China has been seriously affected by terrestrial pollutants, and there is an urgent need for ecological risk assessment of China's coastal environment. The assessment of heavy metal pollution in Hong Kong waters was carried out using different environmental and ecological indicators. The heavy metal contents (Cu, Pb, Zn, Cd, As, Cr, and Hg) in the near coast of Hong Kong were analyzed for two different seasons of the year 2018 (April-spring and September-autumn). We assessed the distribution and enrichment of heavy metals in the near coast of Hong Kong, and the potential biohazardous effects were assessed using the species sensitivity distribution method. The results showed that only Pb, Zn, and Hg in seawater exceeded the Class I standard. Pb, Zn, Cd, and As in organisms exceeded the standard, and no heavy metals exceeded the standard in sediments. The species sensitivity distribution method indicated that the biohazardous factor of heavy metals of the Hong Kong coast is higher in spring than in autumn, and the potential hazard ratio has the characteristics of high northwest and low southeast, which leads to its msPAF also having these characteristics. From the correlational analyses among heavy metals, we found that the pH change in seawater was related to the concentration of heavy metals, the concentration of heavy metals in seawater was proportional to the salinity of seawater, Pb and Cu were likely to have the same source, and Zn and Cd may not have the same emission sources as the other heavy metals. Overall, heavy metal contamination of seawater, sediments, and organisms near the Hong Kong coast was within acceptable limits, but the problem of heavy metal dispersion should be prevented.

Increase in records of toxic phytoplankton and associated toxins in water samples in the Patagonian Shelf (Argentina) over 40 years of field surveys

Historical records (1980-2018) of potentially toxic phytoplankton and phycotoxins on the Argentine Continental Shelf (35°S-56.5°S) and adjacent ocean waters were systematically reviewed from scientific literature to assess their abundance and diversity over spatial and temporal scales. Records increased from 124 in the period 1980-1992 to 638 in 2006-2018, and the scanned area expanded from coastal to offshore waters including the shelf-break front. Alexandrium was the most reported genus (54%) during 1980-1992 and Pseudo-nitzschia (52%) during 1993-2005. By 2006-2018, a higher diversity was documented: Alexandrium (20%), Dinophysis (32%), Pseudo-nitzschia (31%), and the most recently described potentially toxic dinoflagellates of the family Amphidomataceae (8%). Likewise, a wider spectrum of phycotoxins was documented in the last decade, with lipophilic (LSTs) and paralytic shellfish toxins (PSTs) as the most recorded. Increased records are related to intensified monitoring, more detailed taxonomic analyses and more sensitive chemical techniques for marine biotoxin detection. This quantitative assessment brings light to the widespread occurrence of HABs along contrasting areas of the Patagonian Shelf and sets the basis for ecosystem risk evaluation. Moreover, comparison of toxic phytoplankton reported in the SW Atlantic with those in similar temperate seas in the North Atlantic and the Pacific Ocean, disclose ocean basin differences in strain toxicity of A. ostenfeldii, D. tripos and Azadinium species.

Anthropogenic microfibers are highly abundant at the Burdwood Bank seamount, a protected sub-Antarctic environment in the Southwestern Atlantic Ocean

Microplastics debris in the marine environment have been widely studied across the globe. Within these particles, the most abundant and prevalent type in the oceans are anthropogenic microfibers (MFs), although they have been historically overlooked mostly due to methodological constraints. MFs are currently considered omnipresent in natural environments, however, contrary to the Northern Hemisphere, data on their abundance and distribution in Southern Oceans ecosystems are still scarce, in particular for sub-Antarctic regions. Using Niskin bottles we've explored microfibers abundance and distribution in the water column (3-2450 m depth) at the Burdwood Bank (BB), a seamount located at the southern extreme of the Patagonian shelf, in the Southwestern Atlantic Ocean. The MFs detected from filtered water samples were photographed and measured using ImageJ software, to estimate length, width, and the projected surface area of each particle. Our results indicate that small pieces of fibers are widespread in the water column at the BB (mean of 17.4 ± 12.6 MFs.L^-1), from which, 10.6 ± 5.3 MFs.L^-1 were at the surface (3-10 m depth), 20 ± 9 MFs.L^-1 in intermediate waters (41-97 m), 24.6 ± 17.3 MFs.L^-1 in deeper waters (102-164 m), and 9.2 ± 5.3 MFs.L^-1 within the slope break of the seamount. Approximately 76.1% of the MFs were composed of Polyethylene terephthalate, and the abundance was dominated by the size fraction from 0.1 to 0.3 mm of length. Given the high relative abundance of small and aged MFs, and the oceanographic complexity of the study area, we postulate that MFs are most likely transported to the BB via the Antarctic Circumpolar Current. Our findings imply that this sub-Antarctic protected ecosystem is highly exposed to microplastic pollution, and this threat could be spreading towards the highly productive waters, north of the study area.

Alternative Conservation Paradigms and Ecological Knowledge of Small-Scale Artisanal Fishers in a Changing Marine Scenario in Argentina

We studied conservation paradigms of small-scale artisanal fishers and other actors involved in the conservation of the Bahía Blanca Estuary (BBE)-a Southwestern Atlantic estuary under anthropogenic pressures (conservationists, NGOs, individuals in the private sector and the port consortium). We focused on the relationship between fishers and non-human entities (e.g., animals, tides, lunar cycles, etc.) from alternative conservation paradigms according to Pálsson's schema (orientalism, paternalism, communalism). We also explored the ecological knowledge of fisher communities to identify possible conservation strategies. Using an ethnographic approach, we identified communalism as the dominant paradigm within the fisher communities as opposed to the paternalistic and orientalist approaches of conservationists and industry employees in the BBE. Fishers demonstrated a broad knowledge on the effects of climate change on fish stocks and pollution on ocean environments and biota, which gillnets avoid catching juveniles and threatened species, and landscape changes over the long-term period, among others areas that could be useful for conservation of these changing coastal ecosystems. We conclude that understanding local perspectives and practices is essential for a democratic exchange among different bodies of knowledge to conserve marine ecosystems.

Remote Sensing of Ocean Fronts in Marine Ecology and Fisheries

This paper provides a concise review of the remote sensing of ocean fronts in marine ecology and fisheries, with a particular focus on the most popular front detection algorithms and techniques, including those proposed by Canny, Cayula and Cornillon, Miller, Shimada et al., Belkin and O’Reilly, and Nieto et al.. A case is made for a feature-based approach that emphasizes fronts as major structural and circulation features of the ocean realm that play key roles in various aspects of marine ecology.