Coastal Habitat Conservation: New Perspectives and Sustainable Development of Biodiversity in the Anthropocene

Coastal Habitat Conservation: New Perspectives and Sustainable Development of Biodiversity in the Anthropocene offers the latest research and approaches to biodiversity conservation in coastal areas. The book synthesizes the background of foundational conservation views and provides new perspectives and recent strategies within a sustainable development context for coastal species and organic life. Written by a team of international authors with expertise in wide-ranging issues of biodiversity conservation, this book analyzes the challenges of conserving marine habitats and species that humanity faces in the Anthropocene era.

Sections explore emerging and unforeseen impacts within a changing world, specifically, the marine-based conservation in the context of global change, coastal urbanization and mitigation of its environmental impacts, marine bioinvasions, conservation strategies for of out-of-sight communities like caves, habitat restoration, and the citizen science and its challenging role in monitoring conservation.

• Discusses different strategies to deal with various biological and ecological impacts on coastal marine species and habitats
• Offers new insights into the practices of marine conservation in the Anthropocene
• Led by editors whose expertise includes marine biodiversity, marine ecology and marine habitat conservation

• Language: English
• Publisher: Academic Press
• Release date: Jan 18, 2023
• ISBN: 9780323856140

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Chapter 1: Impacts, evolution, and changes of pressure on marine ecosystems in recent times. Toward new emerging and unforeseen impacts within a changing world

Free Espinosaa; Hocein Bazairib,c    a Laboratorio de Biología Marina, Departamento de Zoología, Facultad de Biología, Universidad de Sevilla, Sevilla, Spain

b Mohammed V University in Rabat, Faculty of Sciences, Department of Biology, Rabat, Morocco

c Natural Sciences and Environment Research Hub, University of Gibraltar, Europa Point Campus, Gibraltar

Abstract

Marine ecosystems have been threatened in multiple ways through the time such as overexploitation, pollution, or coastal destruction, but they face new challenges such as the astonishing increase in nonindigenous species or the effects of the global change in the Anthropocene. In this sense, the impacts of increasing sea level, sea surface temperature, and acidification for the marine environment and, specifically, their interactions and modulation under different environmental and biological issues are of future concern. This chapter summarizes the traditional impacts and the emerging ones on marine biodiversity discussing about what is known and what we need to know under the paradigm of sustainable development.

Keywords

Marine conservation; Marine pollution; Overexploitation; Coastal destruction; Nonindigenous species; Global change

1: Introduction

Marine realm has been traditionally a source of mystery, fear, knowledge, and associated with myths and supernatural events. Even currently, many people feel themselves in such a way when facing the vast ocean in spite of the information that we already have about the marine system. It is well understandable because the comprehension about this domain is by far very lower than we have on terrestrial one. This fact has led that our knowledge and consciousness about the environmental impacts that threaten the marine biodiversity and ocean ecosystems had not been in the same level than for terrestrial zones. Moreover, marine biodiversity has been usually hidden from human view by physical constraints, and it has limited our capacity to be aware about the real damage that human interventions have been affecting since coastal areas to open oceans. Unfortunately, humankind has perceived the sea as a mere provisioner for food and a gigantic dump. In this context, it is urgent to develop a sea ethic that values the oceans more than a simple provider (Dallmeyer, 2005).

The main factor underneath the environmental crisis that our planet is facing relies on the exponential population growth in which our species became since the middle of the 20th century (Fig. 1.1). Unfortunately, this kind of growth is expected to continue at least until the middle of the present century, and it will mean that a huge demand on natural resources, predictable habitats destruction, and greenhouse gases intake will continue to increase with the concomitant negative effects.

Fig. 1.1

Fig. 1.1 World population growth during the period 1700–2019 and its projection for the end of 21st century.

Nature dynamics are the result of multiple natural and man-made processes. However, humans are now recognized as the main drivers of environmental change on Earth, and they are having a greater impact on the global environment than ever before (Folke et al., 2021), with an outsized influence on global planetary processes (Zalasiewicz et al., 2017).

Human forces are unevenly distributed around the world. However, the rate at which human impacts are increasing is of particular concern for the oceans (Halpern et al., 2019), especially in coastal areas where human activity and population are concentrated (Bennett et al., 2019). Indeed, 87%–90% of the global ocean surface are affected by humans (Jones et al., 2018). These impacts have resulted in many global environmental changes, thereby leading to a loss of a global biodiversity.

The term Holocene has been used to design the postglacial epoch of the past 10–12,000 years since it was adopted by the International Geological Congress in 1885 after Charles Lyell proposed for the first time in 1833 (Dalby, 2016). During Holocene, humankind emerged as a main force at global scale, driving ecological, morphological, and geological changes, but the invention of the steam engine at the end of the 18th century led the industrial revolution and then the effects of human influence were clearly noticeable in multiple ways (Crutzen & Stoermer, 2000). Therefore, to emphasize the central role of humans in geology and ecology the term Anthropocene for the current geological epoch was proposed by Crutzen and Stoermer in 2000. This term links directly the burning of fossil fuels and greenhouse gases emissions with the concomitant global climate change and the further eco-geological changes (Dalby, 2016).

This chapter gives an updated overview of the traditional forces of change in marine ecosystems as well as the new emerging ones in the Anthropocene era. It also reviews the state of knowledge of their effects and the ways toward marine conservation.

2: Traditional impacts on marine ecosystems: Past, present, and future

The most important human impacts on marine ecosystems have been identified consistently as overexploitation, pollution, coastal destruction, biological invasions by NIS (nonindigenous species), and climate change (Jackson et al., 2001; Probert, 2017 and references therein). Historical sequence of human disturbances was pointed out by Jackson et al. (2001) indicating that fishing was the older human impact over the oceans (Fig. 1.2). Furthermore, this impact could be reliably tracked down since more than 1000 years comparing archeological records with present data on the mean body size of target species by fisheries. In fact, a reduction of more than 80% was detected in some species such as Atlantic cod. Pollution would be the second impact in the timeline that appeared mostly after the industrial revolution during the 19th century and became so intense through the 20th century indeed. The global awareness about the damage inflicted by industrial and urban pollution in the marine ecosystems led to adopt several international agreements in order to reduce pollution such as MARPOL, The United Nations Convention on the Law of the Sea, International Convention on Oil Pollution Preparedness, Response and Co-operation, or London Convention, which entered into force in 1983, 1994, 1995, and 1996, respectively. Technology and engineering development plus human population growth are in the root of coastal destruction by land reclamation from the sea, building infrastructures for preventing coastal erosion, protection against wave action or setting up new harbors or marinas among others, which has been very severe during the past decades (see Chapter 3 for further information in this topic). The most recent threats in getting into the game of disturbing marine ecosystems have been biological invasions and climate change, even though their effects are noticed more recently, they started for a long time. Regarding the impact of NIS, the increasing maritime traffic due to the boosted commercial relationships caused by the globalization phenomenon has brought to the forefront their negative impacts on marine biodiversity and ecosystem functioning in spite of the introduction of marine species by maritime vessels had not been exclusive from the present time. Similarly, the climate change was rooted in the industrial revolution when the emissions of carbon dioxide (CO2) started to increase, but the impressive rate of emissions during the past decades together with the accumulation of such quantities due to the great residence time has provoked an environmental crisis of unprecedented consequences (Benner et al., 2021).

Fig. 1.2

Fig. 1.2 Historical sequence of human impacts affecting coastal ecosystems. Adapted from Jackson, J. B., Kirby, M. X., Berger, W. H., Bjorndal, K. A., Botsford, L. W., et al. (2001). Historical overfishing and the recent collapse of coastal ecosystems. Science, 293(5530), 629–637.

An indirect way to see the relevance of each of the abovementioned impacts and their evolution through time is the number of published scientific articles. In this sense, pollution was a main threat of concern considered by the academia in the 1970s and 1980s, but it was overcome by climate change in the 21st century, being the most relevant impact under study (Fig. 1.3). It is also noteworthy the exponential increase in publications about NIS since the 1980s, being currently the third impact on marine ecosystems that most publications concentrate. Finally, it is worth to notice the few publications about coastal destruction in comparison with the other impacts, although this impact has greatly increased and its role on coastal marine ecosystems is jeopardizing marine biodiversity as it is fully explained in Chapter 3. It might be possible that the articles already published on this topic were more difficult to sum up under a single or few specific keywords as the rest of impacts and this issue was really deeper studied.

Fig. 1.3

Fig. 1.3 Number of publications in logarithmic scale about the main threats for marine biodiversity through time. The publications were obtained using Web of Science searcher with the following combinations: NIS (nonindigenous species AND marine), marine pollution (marine pollution), climate change (climate change AND marine), coastal destruction (coast* destruction OR coast* modification OR coast*alteration OR coast*degradation), marine overexploitation (marine AND overexploitation).

2.1: Overexploitation

Such temporal sequence of threats over the marine realm can change according with geographical areas, type of habitats affected, and other factors involved but overexploitation has been consistently detected as the primary human-induced alteration of the oceans (Jackson et al., 2001). The exploitation of the sea in the modern age has been remarkable. Indeed, cod and whale fisheries strongly contributed to the European economic activity since 16th to 19th centuries (Hilborn et al., 2003). However, in the late 19th century, it was still argued that the main fisheries were inexhaustible (Huxley, 1883), whereas on the contrary others indicated the impoverishing of the sea as the rate of turnover was being overcome by the rate of capture (Garstang, 1900). In fact, targeted marine species, such as bowhead whale (Balaena mysticetus), was going into extinction as far as 1828 off the east coast of Greenland (Allen & Keay, 2001). Moreover, the 20th century has shown the truth of such contention because of reducing and eventually the extirpation of many cetaceans (humpback, blue, fin, sperm, sei, or minke whales), manatees, seals, sea lions, or turtles and depletion of fishing stocks such as salmon, which was widespread in Europe and it is currently absent from many rivers, or cod which was sustainably harvested over 500 years but severely declines since the 1960s (Hilborn et al., 2003; Jackson et al., 2001; Parrish, Behnke, Gephard, McCormick, & Reeves, 1998; Van Blaricon, Gerber, & Brownell, 2013). Furthermore, exploitation of demersal fishes has shown a shift over the past 50 years toward deeper species, which are more vulnerable to overexploitation due to their life-history strategies (Morato, Watson, Pitcher, & Pauly, 2006).

Fishing stocks depletion through the twentieth century has also been promoted due to the so called shifting baseline syndrome (Pauly, 1995) for which fishery scientists in subsequent generations took the baseline of many fisheries as the level reported in such time instead of the potential level that these stocks could achieved because the lack of information about their real natural status. Being like this, degraded systems by decades or even centuries of overexploitation were accepted as the target to achieve.

The future of world fisheries faces a dichotomy: we are able to continue exploiting resources prioritizing economic profit in the short term at the edge of the maximum yield as we have already done with disastrous consequences or, alternatively, we could choose a sustainable and profitable exploitation of fishing stocks allowing the recovering of such depleted stocks and reducing fishing pressure on them using appropriated, well-designed and networked marine protected areas (MPAs), enforcing marine laws, improving maritime spatial planning, and establishing fishing bans according with consistent scientific information (see Chapter 2 for further information on MPAs).

In addition to the reduction of tonnes obtained by extractive fishing caused by the depletion of many stocks, aquaculture has emerged in the last decades as an alternative source for obtaining fish protein. In this sense, the total amount commercialized has recently equal the score with extractive fishing and the trend is that aquaculture almost will double it in 2060 (Fig. 1.4). Even though aquaculture is the most sustainable way to provide fish protein to the humankind, similarly to the shift from hunting wild terrestrial animals to cattle raising, it is not absent from environmental impacts such as eutrophication by means of fish waste or excess in feeding, release of antibiotics into the sea or spreading parasites and diseases to the wild specimens. All these impacts should be carefully considered and find sustainable solutions. In this regard, integrated multitrophic aquaculture (IMTA) is a promising field of research (see Chapter 5 for further details).

Fig. 1.4

Fig. 1.4 Millions of tons extracted by fisheries and aquaculture during the period 1950–2016 and their projections to 2050. Source: Historical data, 1950–2016: FAO (2017b) and FAO (2018). Projections to 2050: Calculated at WRI; assumes 10 percent reduction in wild fish catch from 2010 levels by 2050, linear growth of aquaculture production of 2 Mt per year between 2010 and 2050. See https://research.wri.org/wrr-food/course/increase-fish-supply-synthesis for full paper.

2.2: Marine pollution

There are many different definitions of marine pollution but one of the most widely accepted is the proposed by the Group of Experts on the Scientific Aspects of Marine Pollution (GESAMP), an international group of experts advising United Nations, who defined marine pollution as introduction by man, directly or indirectly, of substances or energy into the marine environment (including estuaries) resulting in such deleterious effects as harm to living resources, hazards to human health, hindrance to marine activities including fishing, impairment of quality for use of seawater and reduction of amenities. There are many different forms of marine pollution, but, summarizing, it is widely reported three main types: chemical, organic, and thermal/radioactive pollution.

Dealing with chemical pollution, several pollutants are affecting the oceans, mainly hydrocarbons, persistent organic pollutants (POPs), and metals (heavy metals and organometals).

Hydrocarbons have been traditionally the focus of an extensive research because of the lethal and sublethal effects on marine biota and the acute and long-term effects. Crude oil is a complex mixture of hydrocarbon (usually >   75%, composed exclusively by carbon and hydrogen) and nonhydrocarbon compounds (composed also by sulfur, nitrogen, or metals) (Kennish, 1997). The most popular classification recognizes aliphatic and aromatic hydrocarbons, being more dangerous for marine life the latter. Nevertheless, aromatic compounds are usually lighter and evaporate early, whereas the aliphatic are able physically to cover animals and plants causing suffocation in the short term. Unfortunately, many oil spills through the time have spread thousands of tons of oil causing severe damages over hundreds of kms such as the crashes of Tampico Maru in 1957 (Baja California), Torrey Canyon in 1967 (Scily Islands), Amoco Cadiz in 1978 (Britain), Exxon Valdez in 1989 (Alaska), Prestige in 2002 (Spain), or Deepwater Horizon in 2010 (Gulf of Mexico). However, after the Torrey Canyon accident, an international agreement for compensating such damages started to be discussed. Finally, the International Convention on the Establishment of an International Fund for Compensation for Oil Pollution Damage (called FUND92) was redacted in 1992 and entered into force in 2006, once signed by 115 countries, to compensate the economic loss due to oil spills, but the liability for high-seas oil pollution is still restricted (Probert, 2017). In this context, the number of spills has shown a significative reduction since the 1970s to the present (ITOPF, 2016) and the emergency protocols, legislation about the oil ships (enforcing for a double hull), and tools to clean the crude have been incorporated and refined. The required transition to alternative sources of energy, to avoid CO2 emissions and reduce the impact of climate change (if it is done), suggests that this type of pollution will be less relevant in the oceans in the coming decades.

Persistent organic pollutants (POPs) have been exponentially used during the latter part of the 20th century (Pintado-Herrera et al., 2017). These are of major concern in marine chemical pollution because they persist in the marine environment, are resilient to degradation by microorganisms (being their resident time quite long), are able to spread over extensive areas and bioaccumulated/biomagnified through the food chain (Olisah, Adams, & Rubidge, 2021). These chemicals are hydrophobic and tend to accumulate in lipid tissues of marine species. POPs include mainly organochloride pesticides (OCPs), polychlorinated biphenyls (PCBs) and polybrominated diphenyls (PBDEs) as principal compounds. Major uses have been pest control in agriculture as pesticides and fungicides for OCPs whereas PCBs and PBDEs have been used in the industry mostly as hydraulic or dielectric fluids, flame retardants and plastic production because of being chemically stables, nonflammables and cheap of producing (Rossberg et al., 2006). Their negative effects such as endocrine disruptors, carcinogenic effects, neurotoxicity, and immune depressors led to their ban in the USA in 1978 and by Stockholm Convention on Persistent Organic Pollutants in 2001. New emerging POPs contaminants are those called plasticizers that are low-molecular weight organic compounds used in the production of plastics, detergents, or soaps (Rosenfeld & Feng, 2011). The most relevant are bisphenol and phthalates that causes endocrine disruptions, development toxicity, altered prostate, and uterus development or deduced sperm count (Smital, 2008). Although intensive research has been done on POPs and some of them have been consequently forbidden based on the evidences, further research is obliged considering the pleiad of chemicals with potential harmful effects within POPs.

Metals (heavy metals and organometals) are also a pollutant of major concern in marine ecosystems. Regarding heavy metals, they can be introduced into the oceans mainly from land-based sources through river runoff, urban sewage, industrial outfalls, or antifouling paints plus aerial deposition (Davies, 1993; Deheyn & Latz, 2006). In fact, antifouling paints are a major source of heavy metals in marine systems, especially in enclosed areas where they are often used such as marinas and harbors (Almeida, Diamantino, & de Sousa, 2007). There are two types of heavy metals, those with biological functions such as Zn, Cu, Fe, Ni, and As and those with no biological relevance such as Cd, Hg, and Pb (Mbandzi, Nakin, Saibu, & Oyedeji, 2021). Nevertheless, all can have pernicious effects on marine organisms when certain levels are exceeded (Rainbow, 2002). The relevance of heavy metals on marine pollution research has obtained stable focus since the early 1990s (Sun, Wang, & Ho, 2012). Moreover, organometals such as tributyltin (TBT) was originally used in antifouling paints but early in 1981 was discovered its environmental risk causing endocrine disruptions in marine invertebrates and the so-called imposex in many marine mollusc species (Smith, 1981). Imposex is a kind of pseudohermaphroditism in which the females develop male features in the reproductive system such a penis and vas deferent that provokes sterility (Smith, 1971). TBTs were banned in the European Union in 2003 (Regulation 782/2003) and at international level in 2008 by the International Maritime Organization which has gradually put TBTs under control. The most modern antifouling paints contain a biocidal based on Cu instead of Sn (Canning-Clode, Fofonoff, Riedel, Torchin, & Ruiz, 2011), but it also represents an intake of heavy metals into the marine ecosystems. This type of chemical pollution, in spite of the increasing law enforcement to reduce its negative effects especially in coastal areas, still represents a main threat to be aware.

Regarding with organic pollution, there are different ways from which organic matter can enter the marine ecosystems causing eutrophication mainly from land-based sources such as sewage outfalls as the most important but also pulp mills, food-processing plants, and fertilizers introduced by runoff from agriculture fields (Probert, 2017). Therefore, eutrophication is driven by nutrient supply that leads a bottom-up control directly affecting the energy that enter to the food web. This energy regulates plant biomass in shallow benthic habitats, structuring marine coastal ecosystems.

Even though improvements and law enforcements about sewage have allowed to control such organic pollution source in several coastal areas, mainly in developed countries since several decades ago, there has been an amazing increase in coastal eutrophication, causing hypoxia/anoxia, habitat degradation, biodiversity loss, and algal blooms (Boesch, 2002; Howarth et al., 2000). Benthic communities are within the most affected assemblages in coastal areas due to eutrophication (Pascal et al., 2022) originating a substantial loss of ecosystem services. Most of this eutrophication is due to nitrogen but also phosphorous is contributing (Howarth & Marino, 2006). Moreover, organic pollution caused by using synthetic fertilizers has increased dramatically in recent decades in parallel to the increase in meat per capita consumption, due to the increase in the surface used as pasture for cattle within the Food in the Anthropocene context (see Willett et al., 2019). Furthermore, the meat and dairy supply chains emit 80% of some greenhouse gases (CH4 and N2O) in the European Union by enteric fermentation and fertilizer application (aan den Toorn, Worrell, & van den Broek, 2021). In this sense, Howarth (2008) reported that more than a half of the fertilizers used were produced since 1985 and nitrogen fluxes have increased until 15-fold or more in some regions. It is urgently required to avoid such a wasteful use of fertilizers improving farming practices without affecting food production (Gabric & Bell, 1993).

Finally, thermal/radioactive pollution is usually a type of pollution that affect at local or regional level even though some radionuclides can be transported aerial or by marine currents to a distant area from the source origin. Thermal pollution is caused by power stations (nuclear or thermal) that use water for cooling and pour the hot plume on coastal areas (>   10–15°C warmer than the surrounding water). Temperature is one of the most important abiotic factors for the distribution and physiology of organisms (Williams & Morritt, 1995), and exposure to high temperatures can have significant physiological consequences to these organisms (Snyder, Girvetz, & Mulder, 2001). Therefore, temperature is a major ecological and biological driver deeply affecting metabolism (food intake or respiration rate), species’ activity and behavior, dissolved oxygen or competition, which have great consequences at ecosystem level indeed.

Regarding with radioactive pollution, it is important to discriminate between natural radionuclides such as K⁴⁰, Th²³⁰, ²³², or U²³⁴, ²³⁸ (Szufa, Mietelski, & Olech, 2021) and artificial ones such as Cs¹³⁷, Sr⁹⁰, or Pu²³⁹, ²⁴⁰, which derived from nuclear weapon tests, nuclear power plants activity, or nuclear facility accidents (Kim, Lee, Lee, & Kim, 2019). In this sense, nuclear weapon tests were carried out mainly in the 1950s and 1960s and there is evidence of their impact on marine species such as turtles with dose rates high enough for lethality and genomic alterations (Johansen et al., 2020). Besides, accidents in nuclear power stations such as Chernobyl in Ukrania and Fukushima Dai-ichi in Japan in 1986 and 2011, respectively, released significant amounts of radioactive material to the marine environment directly or by atmospheric deposition either in the Baltic Sea, Eastern Mediterranean, and Pacific Ocean (Bezhenar, Takata, de With, & Maderich, 2021; Florou, Nicolaou, & Evangeliou, 2010; Kotilainen, Kotilainen, Vartti, Hutri, & Virtasalo, 2021). Overall, Chernobyl catastrophe was worse in terms of radiation released and environmental impacts in several orders of magnitude (Steinhauser, Brandl, & Johnson, 2014). Considering that many radionuclides can remain elevated for hundred or even thousands of years (Johansen et al., 2020), this source of pollution must be carefully taken into consideration. Nevertheless, there are studies indicating that radioactive pollution decays rapidly after some months or even a few years, it is spread and dissolve in the ocean, and it is usually localized in the vicinity of the pollution source, with no deleterious effects on marine species such as blue sharks or dolphin fishes, or remaining below food safety limits in the long term (Bezhenar et al., 2021; Johansen et al., 2020; Men et al., 2020, 2021).

2.3: Coastal destruction

Human population growth and its concentration within the coastal fringe is the ultimate cause beneath of shorelines’ modification worldwide (Hanlon, Firth, & Knights, 2018). However, such modification is also boosted by climate change causing the accelerated sea level rise and repeatedly great storm events for which new structures are built to deal with (Airoldi & Bulleri, 2011). Therefore, coastal and marine infrastructures (CMI) are exponentially being set up elsewhere. This phenomenon has been named urban sprawl, coastal hardening, or coastal armoring (Dugan, Airoldi, Chapman, Walker, & Schlacher, 2011; Firth et al., 2016). CMI support in general lower biodiversity, simpler biological assemblages, higher number of NIS, and provide less ecosystem services than natural shorelines (Airoldi, Turon, Perkol‐Finkel, & Rius, 2015; Hanlon et al., 2018). Some habitats such as mangroves or estuaries are being intensively urbanized and considering the high productivity and diversity that these habitats host, the negative effects are even worse (Ramos, Boto, Blanco-Libreros, & Riascos, 2021). It is important to note that on artificial substrates, there is a lack of microhabitats such as crevices, pits, tidepools, or overhang, which represent a refuge for many species against harsh conditions (strong wave action, desiccation, predation, etc.) (Firth et al., 2016). In this sense, many specialists are not able to colonize CMI and other generalists capitalize on the new conditions leading to a biological homogenization and frequently also to a functional one because functional redundancy is sometimes low depending on the habitat (Ramos et al., 2021). Therefore, the substitution of natural rocky or sandy beaches by human-made substrata is altering the ecosystem functioning as reducing marine biodiversity. To deal with, an intense effort has been done in the recent years to mimic such features on CMI to enhance marine biodiversity by mean of the so called ecological engineering (Evans et al., 2021). Further information on this topic can be found in Chapter 3.

2.4: Nonindigenous species

Human-mediated introduction of marine species far away from their native range has probably taken place since thousands of years associated to sea trips by vessels, which could have carried marine species either in ballast in their holds or as biofouling in their hulls, even though these introductions has been unnoticed (Bellwood, 2007; Boivin & Fuller, 2009). Moreover, the first recorded marine introduction was of the bivalve Mya arenaria from the North West Atlantic to Denmark taking place in 1245 (Petersen, Heinemeier, & Rud, 1992). However, biological introductions grew substantially over the past two centuries in parallel to the exponential increase in world trade, showing most current marine communities some nonnative components (Molnar, Gamboa, Revenga, & Spalding, 2008; Ruiz, Fofonoff, Carlton, Wonham, & Hines, 2000).

Species that settle successfully far away from their native range (nonindigenous species: NIS) usually show shared traits such as fast growth rate, high reproductive output, tolerant to environmental changes (in temperature, salinity, oxygen values, pH, etc.), or abilities to outcompete other species. When these species have negative effects on native species, economic values, or human health the term invasive is used (Davis & Thompson, 2001; Ruiz et al., 2000). Côté (2017) also pointed out the difference between two types of species out of place in the Anthropocene: nonnative and range-shifting for species translocated by humans across geographical barriers and over long distances to the former, and for species that have experienced a range expansion due to environmental changes (i.e., global change) to the latter.

Globally, the increase in marine NIS is astonishing in the recent years, being seven times greater in 2016 comparing with 2008 (Molnar et al., 2008; Pagad, Hayes, Katsanevakis, & Costello, 2016). Furthermore, recent data about the establishment of NIS in the Mediterranean Sea, a hot spot of world marine biodiversity (Coll et al., 2010), indicate an increase in the established species greater than 40% in the period 2010–21, showing an acceleration during the past 2 years of the period (2020 and 2021) (Zenetos et al., 2022). Therefore, the future of marine bioinvasions is worrying enough to deserve attention by scientists, environmental managers, and policymakers to design strategies to prevent invasions (regulations about ballast waters, biofouling, and aquaculture trade), establish monitoring surveys to make possible early detection of invasive species and develop protocols of eradication to implement after such detections. Further information on this topic can be also found in Chapter 4.

2.5: Climate change

During the Pleistocene, the climate fluctuates periodically between glacial and interglacial periods where the levels of CO2 ranged from 172 ppm (glacial) to 300 ppm (interglacial) during the last 800,000 years (Lüthi et al., 2008, Fig. 1.5). In the past 10,000 years the Earth came into a warm interglacial period with values of CO2 around 260–280 ppm (Bereiter et al., 2015). However, since the industrial revolution such concentration increased dramatically from 280 ppm in 1813 to 410 ppm in 2019, originated by fossil fuel burning with smaller contributions of land use change and cement manufacture (Karnauskas, Miller, & Schapiro, 2020; Rubino et al., 2013). This unprecedent levels of CO2 levels in the past 55 million years of geological record (Gingerich, 2019) have a clear human origin and has had a deep influence at planetary scale and constitutes a driver of global change in Earth trajectory. Nevertheless, the increase in CO2 levels, even rooted in the industrial revolution, has experienced great increase in a very short period since the 1980s (Doney, Busch, Cooley, & Kroeker, 2020). Moreover, the mean lifetime in the atmosphere for some of the greenhouse gases is long (>   100 years for CO2, decades for CH4; see Eyring et al., 2010), being the climate affected in centennial timescales according to the emissions of such gases right now.

Fig. 1.5

Fig. 1.5 CO 2 concentration during the Pleistocene/Holocene. Data accessible in Bereiter, B., Eggleston, S., Schmitt, J., Nehrbass‐Ahles, C., Stocker, T. F., Fischer, H., …, Chappellaz, J. (2015). Revision of the EPICA dome C CO2 record from 800 to 600 kyr before present. Geophysical Research Letters, 42(2), 542–549.

Climate change is evident by global warming, which in the ocean is increasing the sea surface temperature (SST) in many areas with greater occurrence of extreme ocean warming events and causing mass mortality on marine benthic assemblages (Garrabou et al., 2019). Besides, isotherms are moving across the globe (200 km/decade) inducing climate velocity of many species that are moving polewards after temperature increases at a speed reported for fishes around 45–49 km/decade (Cheung et al., 2009; Pinsky & Selden, 2017). In addition to SST increase, ocean acidification and carbonates reduction are also consequences of the climate change in the marine realm, affecting key habitats such as coral reefs, kelp forests, or seagrasses (Doney et al., 2020). Therefore, the magnitude of this impact and the residence time of greenhouse gases turns this threat as the most formidable challenge that humankind faces not only in the 21st but also in the whole history of our species. It is urgent to adopt radical measures (CO2 emissions must be reduced nearly zero, see Matthews & Caldeira, 2008) to stabilize global temperatures and avoid the crash of our planet, guaranteeing a real sustainable development of human societies.

3: New emerging impacts within the Anthropocene: Is really a sustainable development being achieved?

Generalized biodiversity and habitat loss due to the increased anthropogenic impacts during the past decades have arisen global awareness about the necessity of preserve ecosystems’ integrity and the services they provide to humankind. On the other side, economic constraints have pulled on the opposite way leading to exert more pressure on these ecosystems already threatened. In this context, the term sustainable development was conceptualized in 1987 when the Brundtland Report was presented to the United Nations and incorporated in the third principle of the Rio Declaration in 1992 after the United Nations Conference on Environment and Development that took place in Rio de Janeiro (Brazil). It implies the use of natural resources to satisfy present human requirements without compromising the requirements of the future generations. Since then, it has been the totem word not only in environmental policy but also in general policy worldwide. Despite the increasing awareness in conservation from this inflection point that has been translated into law enforcements for nature protection, the conservation goals defined in 1992 are far from being achieved. Moreover, new emerging impacts are adding up and pushing many ecosystems to the edge of severe breakdown. Although other impacts could be considered or even some would not be strictly new, we discuss about some impacts that represent new challenges in marine conservation from our point of view.

3.1: Global warming and marine heat waves

One of the most important emerging impacts in the Anthropocene is the global warming of the seawater due to the abovementioned climate change, and all the derivatives that we are starting to unravel. How affects the global warming at individual physiology, population demography, species distribution, or species interaction within community level is far of being fully understood even though an impressive scientific effort has been made in this sense during the past two decades (see Pinsky & Selden, 2017). At individual level, warming of the water column could be beneficial in some ways, improving physiological performance and increasing physiological rates up to 20% in ectotherms (Seebacher, White, & Franklin, 2015), which could be advantageous for escaping from predators or to capture a greater food intake. However, continued warming leads to physiological stress when thermal tolerance ranges are overcome. At population level, demographic rates can be affected, unbalancing births and deaths which limit the resilience of many populations to harvesting (Pershing et al., 2015). At species level, it has been found several examples of shifts in geographical distribution, especially of cold-water species migrating toward the pole such as small pelagic fish that are affecting fisheries worldwide (Lima et al., 2022). Finally, at community level, it has been reported community changes mediated by global warming such as those from macroalgal to coral shifts by increased competition of corals from warmer areas into the contracting temperate algae in addition to the increased herbivorous grazing of expanded tropical fishes (Kumagai et al., 2018). Furthermore, marine heat waves (MHWs) are also events that punctuate the global warming causing major episodic mortalities in several marine benthic taxa. The Mediterranean, a hot spot of biodiversity and severely threatened by global warming, is experiencing an acceleration of the ecological impacts of MHWs affecting their ecosystems’ health and functioning (Garrabou et al., 2022).

3.2: Acidification

Acidification is another emerging impact also derived from climate change and the high CO2 levels, like MHWs, and during the past two decades, it has moved from being a frontier science into a well-defined and established subdiscipline (Doney et al., 2020). How marine organisms will respond to both threats (climate warming and acidification) rely on phenotypic plasticity for dealing with new environmental conditions (Chevin, Collins, & Lefèvre, 2013). In this sense, they could evolve much faster than we thought via transgenerational impacts on the epigenome (chemical modifications of the DNA that alter its function and can be heritable) as it has been reported in sea urchins (Strader, Wong, Kozal, Leach, & Hofmann, 2019). Even though the marine acid-base chemistry is complex, briefly the atmospheric CO2 (increased mainly by burning of fossil fuel) dissolves into the water and reacts with it liberating ion bicarbonate and hydrogen ions. Such hydrogen ions lower the pH (acidify the water) and react as well with carbonate ions producing more bicarbonate ions and, ultimately, affecting the solubility of carbonate minerals (Fig. 1.6; see Zeebe & Wolf-Gladrow, 2001 for further details). Moreover, the main findings indicate that ocean acidification enhances primary producer biomass and reduces taxonomic diversity (Fabricius et al., 2011). Regarding with the former effect, it can lead to increase toxic algal blooms or enhance turf algal communities (Fu, Tatters, & Hutchins, 2012; Ober, Diaz-Pulido, & Thornber, 2016), whereas the latter could affect functional diversity and, thereby, loss of ecosystem services considering the low functional redundancy in marine ecosystems (see Doney et al., 2020).

Fig. 1.6

Fig. 1.6 Ocean acidification process. From Hoegh-Guldberg, O., Mumby, P.J., Hooten, A.J., et al. (2007). Coral reefs under rapid climate change and ocean acidification. Science, 318,