Marine ecosystem covers two-thirds of the earth’s surface, and is characterized by its rich biodiversity and endemism of marine life. However, like many other ecosystems, it has been subject to diverse anthropogenic pressures, such as climate change, pollution, and biodiversity losses. In the first part of the book, we discussed the pollution dynamics of the inorganic pollutants (heavy metals, metalloids) and organic pollutants including persistent organic pollutants (POPs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), microplastics, nutrients, and algal blooms in the marine environment. Marine pollutants can have a wide range of pollution sources that are able to cause deleterious effects on marine flora and fauna. The second section of the book specifically elucidates the toxicity assessment by using marine model organisms. It provides extensive new insight into screening biomarker genes combined with advanced gene editing applications. In the last section of the book, various remedial techniques, such as bioremediation and phytoremediation, were discussed whether it could be beneficial to deal with the challenges of marine pollution.

Marine life remains far less well documented than terrestrial biodiversity. The main reason resides in the vastness of the ocean. Ocean waters, with an average depth of ≈3,800 m, cover 71% of the world’s surface. The difficult access, the complexity of the logistics (any study below the top few meters of the ocean requires large means, specialized personnel, and equipment), and the high cost of research have determined the majority of studies being performed in the terrestrial environment. However, in recent times, this severe imbalance has started to reverse. This is mainly due to the implementation of supra-governmental cooperation programs. Due to human-driven ecosystems alteration, over-fishing, ocean acidification, and chemical pollution (together with other threats), multiple marine species are endangered, so this effort is more than ever relevant and eminently urgent. Recently, the Global Ocean Observing System (GOOS) has proposed, the development of an integrated framework for continued and systematic ocean observation. This framework is based on Essential Ocean Variables (EOVs) aiming to provide a credible response to scientific and societal issues, a high feasibility for sustained observation, and cost-effectiveness. Ecosystem EOVs have been developed. In this framework, biodiversity will be assessed based on the status of ecosystem components, nominate phytoplankton biomass and diversity, zooplankton biomass and diversity, fish abundance and distribution (as well as marine turtle, bird and mammal abundance and distribution). Recommendations for each EOV, including what measurements are to be made, but up to this point those recommendations do not exist. This chapter will try to identify common sampling procedures for the most diverse and abundant marine organisms considered as ecosystem components under the EOVs, i.e., phytoplankton, zooplankton, and fish.

In this chapter, aspects concerning the complexity of marine chemistry were discussed. In this scope, important reactions of metals and non-metals with inorganic and organic constituents of water and sediments were considered. In addition to these reactions, this chapter considers biokinetic aspects, which are responsible for very important regulations concerning the assimilation and biotransformation of many chemical elements. Finally, two major environmental problems (eutrophication due to the excessive supply of nitrogen and phosphorus, and release of organotin compounds and copper from antifouling paints used on ships’ hulls) were presented with the intention of discussing some forms in which uncontrolled introductions of metals and non-metals can change negatively the quality of marine ecosystems.

This chapter deals with aspects concerning the presence of sulfur, aluminum, arsenic, cadmium, lead, mercury, and nickel in marine environments. For each of these elements, information about their natural and anthropic sources, as well as their toxicity and accumulation in different organisms, was provided. It was shown that the total accumulation of aluminum, cadmium, lead, mercury, and nickel in physical marine compartments (water, particulate matter, and sediments) is not necessarily related to the bioaccumulation of these elements, since many aspects concerning the bioavailability (including chemical speciation) should be considered.

While the biomass of marine ecosystems is only about 1% of their terrestrial counterparts, their productivity rivals that of all land-based ecosystems taken together. The structure and performance of these ecosystems are strongly affected by environmental factors, such as temperature, nutrients, transparency, solar visible and UV radiation. Increasing pollution, not only of coastal habitats but also of open ocean waters, results in changes in productivity and species composition. Persistent organic pollutants (POPs) are organic chemicals that are not degraded for long periods and include brominated flame retardants, perfluoroalkyl compounds, fluorotelomer alcohols, perfluoroalkylsulfonic acids (FPSAs), perfluorocarboxylic acids (PFCAs), fluorotelomer carboxylic acids, fluorotelomer sulfonic acids, and fluorinated polymers. Pesticides enter the aquatic ecosystems with terrestrial run-off, but are distributed not only in coastal areas and estuaries. Microplastics are of growing concern since they are concentrated in oceanic gyres. They are ingested by plankton and accumulated in the food chain. Accidental oil spills and catastrophic events are the reason for the pollution by crude oil and its products. Mineral oil pollution has been found to affect all the biota from plankton, via invertebrates to vertebrates.

Marine ecosystem is rich and diverse, and plays a vital role in maintaining the natural balance of the planet. Though, the chemical revolution brought many benefits to human civilization but it also affected natural ecosystem due to chemical pollution. Unfortunately, oceans are one of environmental compartments that is at the most receiving end of the chemical pollution. There is a need to monitor chemical pollution in oceans for its normal functioning and providing a healthy habitat to marine biota. The chemical pollution of polychlorinated biphenyls (PCBs) is one of the most prominent types of organic contamination in the oceans. PCBs, comprising of 207 congeners, are considered legacy contaminants. PCBs are banned because of persistent, bioaccumulative and toxic attributes. Being hydrophobic in nature, they tend to bioaccumulate and bio-magnify, causing human health concerns that many of the sea organisms serve as food to human beings and other living organisms through food chain. Monitoring of PCBs in oceans can be done through various methods/techniques involving bio-indicators, biological monitoring, chemical monitoring, biomarkers and through isotopic analysis. The use of any single technique may not help in achieving the maximum control and monitoring of PCBs; so a use of combined approach is recommended to ensure proper monitoring of PCBs in the marine environment.

Pollution in coastal waters is quickly becoming a conspicuous problem throughout the world and the coastal areas of Pakistan are also included in severely affected and therefore no exception. Anthropogenic activities are generally accountable for the deprivation of the marine environment along with their resources across the ocean bodies. The oceans economy not only offers significant development opportunities but also raise some challenges. Not only marine sources, the land-based sources are the prominent contributor of pollution as add in the pollution through direct and indirect wastes discharge as well as effluents in the adjacent coastal waters from untreated domestic and industrial sources. In this chapter, the magnitude of pollution (organic and inorganic) in coastal environments of Pakistan was discussed including plastic pollution as in recent days, it’s a hot issue and a detailed topic itself. The weathering material, river runoff, industrial and domestic waste water enter through different channels and take part in coastal pollution. Most of the pollutants like pesticides, herbicides, heavy metals and macro-nutrients, presented intensification in a marine environment. Nutrient dynamics and their cycling influence the process of eutrophication in the adjacent coastal waters and an enrichment of macro-nutrients in coastal waters reveals an increment in the explosion frequency of harmful algal blooms were reported. The animal manure, sewage treatment, runoff of fertilizers, storm water runoff, plant discharges, and power plant emissions, and failing septic tanks are the primary sources of nutrient pollution. The algal blooms are responsible to produce algal toxins or red-tide toxins and these naturally-derived toxins harm the organisms, including humans. These bloom toxins initially contaminated the fish or seafood species, then responsible for significant loss of fish and shellfish species and ultimately economy damage.

Heavy metal pollution in the marine environment has been realized and developed to an important environmental problem since the 1950’s. In the polluted areas, marine organisms are exposed to high level of heavy metals via different routes, accumulate them in the body, and may have harmful effects from molecular level to population level. Heavy metals in marine fish have been taken much attention due to human consumption and health. Marine fish accumulate heavy metals depending on the concentration and species of metals in water and food, and trophic level, ionic physiology, feeding habits (carnivorous, herbivorous or omnivorous), habitats (demersal, pelagic, or bento-pelagic), growing of fish, and other factors. Consequently, the concentrations of heavy metals in marine fish vary considerably among species and different sites, which can be well explained by the biokinetic model. High levels of heavy metals in marine fish can induce various acute and chronic toxic effects, including behavioral changes, organ pathological changes, biochemical and physiological changes, hematological changes, and so on. Heavy metal-contaminated fish consumption will pose threats to organisms at higher trophic level and humans. Here, we review the occurrence and chemistry of heavy metals in the marine environment, bioaccumulation, and toxicity of heavy metals in marine fish, and the general risk assessment of heavy metal in fish to human health.

The increasing global production and widespread use of plastic have led to an accumulation of large amounts of plastic debris in the ocean. Microplastic exists in the marine environment on a global scale and can harm a great variety of marine organisms. Pollution caused by microplastic and associated pollutants, such as organic chemicals and heavy metals, threatens the survival of marine organisms. In this chapter, the following contents are summarized: (i) the distribution of microplastic in marine environment; (ii) the presence of microplastic in marine environment and organisms; (iii) the effects of microplastic on marine ecology, including the toxic effects on marine organisms, the effects on distribution of pollutants, and the combined pollution caused by microplastic and associated pollutants; and (iv) several aspects to work on the management and research of microplastic are proposed. Extensive research on microplastic pollution is going on.

Evaluating the toxicity in flora and fauna due to marine pollutants has attracted immense scientific, regulatory and public attention over the past years. In recent years, types and levels of contaminants in the marine environment have increased as a result of anthropogenic activities worldwide. These chemical substances are accumulated in the tissues of marine organisms and exerting harmful impacts on marine flora and fauna. Published literature on the biological effects of marine pollution revealed that the effects and distribution of marine pollutants have been increased significantly. This chapter focuses on better understanding of the toxicity evaluation of marine biota and has been divided into four main sections: (i) categories of marine pollutants affecting marine flora and fauna (ii) pollutant sources, routes of exposure and toxicological impacts on marine organisms (iii) impacts of pollutants specifically on marine flora (iv) bioassay studies at the organism level discussing marine toxicity.

Marine medaka (Oryzias melastigma) has been recognized as an ideal marine model fish widely used in the estuary and marine toxicological studies because of multiple favorable attributes, such as small size, short generation cycle, transparent embryos, sexual dimorphism, ease of maintenance, and wide range of salinity and temperature adaptations. Many studies have been conducted on both wild-type and transgenic fish O. melastigma model to evaluate the adverse effects by selecting specific biomarkers of the estuary and marine environmental pollutants. This review provides a recent research progress of the physiological effects and responsive biomarker of O. melastigma caused by various marine pollutants, including heavy metals, endocrine disruptors, and organic pollutants. Of note, this chapter summarizes the progress on whole-genome sequencing of O. melastigma, and promotes novel insights into the use of O. melastigma in future toxicity screening studies, targeting genetic biomarkers that highly activated by marine chemical pollutants using cuttingedge gene editing technique and bioinformatics system.

A fauna or flora that was not native to the particular environment and caused harm by its proliferation was considered an invasive species. This is one among the major concern for protecting the biodiversity as well as economic loss. However, in the marine environment, this problem is further complicated due to less barrier and other common factors, such as movement of the vessels, the release of ballast waters by the tankers, and water currents. The marine Island environment concern has gain significance due to the larger distribution of benthic faunal community and its biodiversity. A study was carried out to understand the status of this problem with reference to Andaman island environment and a probable mechanism to be implemented and their status was discussed in this article.

As indicated by the World Conservation Union, obtrusive invasive species are the second most critical danger to biodiversity, after natural disasters. In their new environments, invasive alien species move to become predators, contenders, parasites, hybridizers, and affect native plants and creatures. Higher rates of multiplication, less normal predators and capacity to flourish in various conditions are some basic qualities, which can make them hard to control. Marine environments are among the most important ecosystems both from a monetary and ecological point of view. The complexity of marine biological communities and their area postures challenges for administration, valuation, and the foundation of sound strategy to defend them for these invaders. Different procedures, for example, aquarium exchange, aquaculture, channel development, dispatching, and live fish exchange have achieved the dispersal of creatures. These dispersal systems result generally in the modification of biodiversity and achieve monetary misfortunes on fisheries. Starting with a short prologue to intrusive species, this section investigates a couple of vital life forms that represent a genuine risk to the earth and the mode by which they spread. This section additionally clarifies the different effects caused by these species and the courses by which they could be controlled.

The conservation of biological diversity and the sustainable use of its components are the major objectives of the Convention on Biological Diversity (CBD). To achieve these objectives, many marine protected areas (MPAs) were identified and developed. The success of these protected areas depends upon several factors of local concern. The failure of coastal and marine biodiversity protection was mainly caused by the environmental changes influenced by anthropogenic activities, overexploitation of resources, habitat loss because of developmental activities, and natural change in climate. This chapter highlights the status of these activities in the island environment and provides potential strategies for its protection by mainstreaming biodiversity with people’s participation.

Aim of this study focused on monitoring the environmental indicators and bacterial pathogens level based on the aquaculture practices that impacted on the Muthupettai mangrove ecosystem. Water samples were collected at five stations during the pre-monsoon season, and samples were analyzed by standard methods. The results of environmental parameters were shown as follows: temperature (31.4-33.2 °C), pH (7.9-8.6), EC (12-14 mS/cm), TSS (4650-5500 mg/l), TDS (36400-41650 mg/l), TS (41250-46450 mg/l) and DO (2.2-4.1 mg/l); total heterotrophic bacteria (72-294 102 cfu/mL), total coliform bacteria (9-150 101 cfu/mL), fecal coliform bacteria (4-135 101 cfu/mL), total Enterococcus bacteria (1-10 101 cfu/mL) and E.coli (2-46 101 cfu/mL); and the Pathogens: total Vibrio species (1-6 101 cfu/mL), total Salmonella species (1-3 101 cfu/mL), total Shigella species (1-2 101 cfu/mL), and total Klebsiella species (1-39 101 cfu/mL). These results were more vulnerable to the ecosystems and highly exceeded the standard permissible limits of the WHO, EU, and CPCB. Continuously discharges of untreated aquaculture effluents deteriorated the mangrove ecosystem qualities. Therefore, there is a need for a regular monitoring and systematic waste management from aquaculture, which can develop sustainable aquaculture and strictly follow the recommended management rules and regulations of aquaculture practices at national or regional level. Further research needs to improve the ecosystems qualities and maintain the rich biological diversity in the Muthupettai mangrove ecosystem.

Marine environment gets polluted due to a range of contaminants including heavy metals. Various physicochemical methods available conventionally for heavy metal remediation suffer from one or the other limitation. Bioremediation is an encouraging solution to heavy metal pollution. Microbes are endowed with diverse potentials to combat heavy metal stress. In this chapter, major sources and effects of heavy metals, factors influencing heavy metal bioremediation, the microbial mechanism for heavy metal detoxification and transformation and involvement of marine microorganisms in heavy metal bioremediation have been discussed.

Contamination by various hazardous compounds released due to sea-related activities has received great concern about the pollution of the marine ecosystem. Nowadays, polycyclic aromatic hydrocarbons (PAHs) are immerging as critical pollutant with context to the marine environment due to some distinctive properties, which makes them persistent organic pollutants (POPs) posing threat to the environment. PAHs make their way in marine environment through various natural and anthropogenic sources. Marine microorganisms have reported to be leading candidates for PAHs degradation. Recent advancements in genomics, proteomics, and metabolomics technologies have gathered significant increment in the knowledge of ecology, physiology and regulatory mechanisms of microbial communities involved in PAHs remediation. Morden technologies will be a vital approach to reveal the mechanisms involved in the bioremediation of pollutants and will offer more insights as yet more uncultivable microbial diversity attached with pollutant degradation.

This chapter encompasses the final words and summarized the current status of marine pollution globally in terms of the distribution, potential sources, associated hazardous impacts, and possible bio-remedial measures. This chapter is divided into two sections and highlighted the viewpoints about different topics discussed in this book and the concluding remarks.