This chapter introduces the historical development of aquaculture, insight into the variety of techniques used to rear a range of different organisms, the technology employed to increase productivity, and the environmental and biological consequences of aquaculture in marine ecosystems. As in any food production system, aquaculture creates its own environmental problems. It has led to disease outbreaks, over-harvesting of forage fishes to generate fish-meal, and genetic dilution of wild stocks from farm escapees, and it has caused ecological problems in areas where local carrying capacity has been exceeded. In addition, aquaculture has its own emerging issues that have extended beyond simply a consideration of biological or environmental science. As aquaculture involves the rearing of organisms in an artificial environment, there are potential welfare issues that are of concern to wider society, and concerns about labour conditions (modern slavery) are now much higher on the societal agenda.
This chapter describes behavioural ecology, which is the study of the ecological and evolutionary basis of animal behaviour. It highlights three aspects of behaviour particularly important in ecology: foraging behaviour, mating behaviour, and living in groups. An individual's ability to survive and reproduce depends in part on its behaviour. This observation suggests that natural selection will favour individuals whose behaviours make them efficient at activities such as foraging, obtaining mates, and avoiding predators. Indeed, animals make behavioural choices that enhance their energy gain and reduce their risk of becoming prey. The chapter then considers the optimal foraging theory, before looking at how mating behaviours reflect the costs and benefits of parental investment and mate defence. It also identifies the advantages and disadvantages of living in groups.
This chapter addresses the effects of large-scale geographic processes on one of the most recognizable ecological patterns known: the distribution and diversity of species on Earth. The study of the variation in species composition and diversity among geographic locations is known as biogeography. The chapter then considers how patterns of species diversity and distribution vary at global, regional, and local spatial scales. Global-scale biogeography is the result of variations in speciation, extinction, and dispersal at latitudinal and continental spatial scales and evolutionary time scales. Regional-scale biogeography (gamma diversity) encompasses a smaller geographic area in which the climate is roughly uniform and the species contained therein are bound by dispersal limitation to that region. Local-scale biogeography (alpha diversity) is equivalent to a community and is determined by dispersal, physical conditions, and species interactions.
This chapter evaluates the biosphere, using the biome concept to introduce the amazing diversity of terrestrial life. Biomes are large-scale biological communities shaped by the physical environment in which they are found. They are categorized by the most common growth forms of plants distributed across large geographic areas. Terrestrial communities vary considerably—from those in the warm, wet tropics to those in the cold, dry polar regions. The chapter then introduces a system of nine biomes: tropical rainforest, tropical seasonal forest and savanna, desert, temperate grassland, temperate shrubland and woodland, temperate deciduous forest, temperate evergreen forest, boreal forest, and tundra. It also looks at freshwater biological zones and marine biological zones. Biological zones in freshwater ecosystems are associated with the velocity, depth, temperature, clarity, and chemistry of the water. Meanwhile, marine biological zones are determined by ocean depth, light availability, and the stability of the bottom substrate.
Change in Communities
This chapter assesses the agents of change in communities, and their effects on community structure over time. Agents of change include both abiotic and biotic factors. Abiotic agents of change can act as disturbances (injuring or killing organisms) or as stresses (reducing the growth, reproduction, or survival of organisms). Biotic agents of change include negative species interactions such as competition, predation, and trampling. The chapter then considers the basics and mechanisms of succession, which is the process of change in species composition over time as a result of abiotic and biotic agents of change. Communities can follow different successional paths and display alternative states. Alternative stable states occur when different communities develop in the same area under similar environmental conditions.
This chapter reviews the mechanisms that have resulted in climate change and looks at the evidence for this change, with a focus on the oceans. This is then followed by examples of how the marine environment has responded to these changes. In particular, the chapter focuses on the impacts of temperature change, ocean acidification, and sea-level rise. It also looks at how natural climatic cycles can both show much about the likely future impact of increasing temperatures and exacerbate the impacts of longer-term warming. However, the main purpose of the chapter is to provide the evidence of what is known about climate change and its impact on the marine environment rather than predicting what may happen in the future.
This chapter examines competition, a non-trophic interaction between individuals of two or more species in which all species are negatively affected by their shared use of a resource that limits their ability to grow, reproduce, or survive. It specifically focuses on interspecific competition (between individuals of different species) as opposed to intraspecific competition (between individuals of a single species). Because resources are the mitigating factor in the interaction, and each species requires and obtains resources in different ways, the mechanisms used to compete and the intensity and ultimate outcome of competition can vary widely among species. The chapter then looks at the concepts of competitive coexistence and resource partitioning (or niche partitioning). Competing species are more likely to coexist when they use resources in different ways. The chapter also considers the Lotka–Volterra competition model.
This chapter highlights the development and drivers of marine conservation; the ways in which conservation issues are identified and prioritized; and some of the ways in which marine conservation has sought to find a way to accommodate the short-term needs, aspirations, and expectations of humans. It also describes how conservation policy is developed and implemented, and gives some examples of successes and failures of conservation initiatives. In dealing with issues of conservation and sustainable development, the marine ecologist enters a wide arena, where practice and policy are swayed by ethical, cultural, political, social, and economic values. But this is also a challenging and rewarding arena, where science can play a role in making a difference to the future state of the seas and oceans as well as to the people depending on them. As the chapter shows, practicing marine scientists can contribute to conservation and management in various ways.
This chapter highlights conservation biology, which is the scientific study of the amount of biodiversity (including genetic diversity, species richness, and landscape diversity), how human activities are impacting it, and how best to maintain it and prevent its loss. It explains why biodiversity is declining and looks at the strategies conservation biologists use to address conservation problems. Primary threats to diversity include habitat loss, invasive species, overexploitation, pollution, disease, and climate change. Conservation biologists use many tools and work at multiple scales to manage declining populations. These include genetic analyses, population viability analysis (PVA), and ex situ conservation. Prioritizing species helps maximize the biodiversity that can be protected with limited resources.
This chapter explores different conservation strategies and the important debate on the best way to conserve ecosystems. Nature protectionists insist that people-free Protected Areas are the only proven method while social conservationists insist that the sustainable use of wildlife with social justice for local people is the only long-term solution. Evidence shows that five elements need to be present for marine Protected Areas to be effective, including the engagement of local people. Global international conservation has the right priorities, but enacting them is hard; for example, the plan for UK conservation calls for a wildlife-friendly landscape, with a large expansion in reserve area and connectedness, together with more effective management. There is not necessarily any conflict between biodiversity conservation, agricultural production, and human wellbeing. The trick is to find the win-win-win solution.
Conservation, Ecology, and Science
This chapter discusses the relationship between conservation, ecology, and science. The big problem facing human beings, and all other organisms on the planet, is that the ecological footprint of humans—the area of biologically productive land needed per person per year to sustain their lifestyles—exceeds the ability of the Earth to support it. This environmental crisis will drive many species to extinction. The extent to which these extinctions matter depends on what the species actually do in ecosystems. The chapter then looks at the importance of biodiversity. Apart from dealing with living evolving organisms that are individually different, there are other important aspects of ecology (and hence conservation) as a science. Some of these are: that it involves the hierarchical structure of nature; that it involves huge changes of scale; and that there are many different kinds of explanations for the same thing.
Francis Gilbert and Hilary Gilbert
Conservation starts off by looking at conservation, ecology, and science and describing how they relate to each other. It then examines populations and how they may change in relationship to movement and the size of suitable habitat available, covering also processes that lead to extinction. Other topics include interactions among different species and the processes through which ecological communities are created. Ecosystems are treated next with a look at their relationship to human wellbeing. Finally, the text examines different human attitudes towards nature, including those of indigenous people, and different conservation strategies.
Continental Shelf Seabed
This chapter examines systems pertaining to the continental shelf seabed. Continental shelves are the most heavily exploited and utilized areas of the world's oceans and support the greatest level of biological production. The ecology of the shallow shelf areas is strongly influenced by physical processes such as waves, tides, currents, erosion, and inputs of material from the adjacent land mass. These processes generate a great diversity of ecosystems and habitats at regional and local levels. The composition of the seabed and its associated biota are a direct reflection of past geological events and current physical processes that act upon it. The continental shelf seabed varies greatly. Furthermore, the benthic community is a critical link in the transfer of organic material and nutrients from the water column above to the seabed.
Coping with Environmental Variation: Energy
This chapter reviews the different ways in which organisms acquire energy to meet the demands of cellular maintenance, growth, reproduction, and survival. It focuses on the major mechanisms that allow organisms to obtain energy from their environment, including the capture of sunlight and chemical energy and the acquisition and use of organic compounds synthesized by other organisms. The chapter then differentiates between autotrophy and heterotrophy. Autotrophs convert energy from sunlight (by photosynthesis) or inorganic chemicals (by chemosynthesis) into energy stored in the carbon–carbon bonds of carbohydrates. Photosynthetic responses to variation in light levels, water availability, and nutrient availability include both short-term acclimatization and long-term adaptation. Meanwhile, heterotrophs acquire energy by consuming organic compounds from other organisms, living or dead.
Coping with Environmental Variation: Temperature and Water
This chapter details the interactions between organisms and the physical environment that influence their survival and persistence, and therefore their geographic ranges. The study of these interactions is known as physiological ecology. The physical environment affects an organism's ability to obtain energy and resources, thereby determining its growth and reproduction and, more immediately, its ability to survive the extremes of that environment. The physical environment is therefore the ultimate constraint on the geographic distribution of a species. The chapter then differentiates between adaptation and acclimatization. It considers responses to environmental variation. The temperature of an organism is determined by exchanges of energy with the external environment. Meanwhile, the water balance of an organism is determined by exchanges of water and solutes with the external environment.
This chapter explores coral reefs. Coral reefs support some of the most diverse and productive communities in the marine environment. Living corals are animals that create limestone formations that may be thousands of kilometres long and hundreds of metres deep. Species' diversity on reefs can equal that in rainforests, but reefs are generally more accessible and easier to observe. The dynamics of reef organisms are complex, supporting high diversity and carbonate growth potential. For millions of people in the tropics, reefs are the main source of food, building materials, and income. However, as the chapter shows, coral reefs around the world are increasingly under threat from changes in climate, sedimentation, fishing, and pollution. Current reef research is thus focused on how to best manage reefs for their long-term survival.
The Deep Sea
This chapter explores the deep sea, which represents the largest, yet least-known, biome on earth. The environment is remarkably constant across the ocean floor: cold, dark water overlying soft, deep mud. While the high hydrostatic pressure is the most obvious physical feature of the deep, it is food supply from the surface that is the limiting factor for life on the abyssal plain. In temperate areas, the food input can be seasonal, providing cues for reproductive cycles. Due to the lack of food, the community of animals in the deep sea is at much lower densities than in shallow waters. Potentially there are millions of species inhabiting the deep-sea benthos; the main groups of large, mobile organisms are echinoderms, decapod crustaceans, and fish. Recent exploration using submersibles has revealed exciting 'island' habitats in the deep sea with a level of production and diversity higher than their surrounding environments.
William D. Bowman and Sally D. Hacker
Ecology starts off with an introduction to the ‘web of life’. The rest of the text is composed of seven units. Unit 1 looks at organisms and their environment. Unit 2 is about evolutionary ecology and includes behavioural ecology. The next unit looks at populations: population distribution, dynamics, and growth. Then the text turns to species interactions which includes predation, parasitism, competition, mutualism, and commensalism. Communities are considered next. What are communities? How do they change? What does species diversity mean? The sixth unit examines ecosystems. The final unit looks at conservation biology, landscape ecology, and global ecology.
Ecosystem Services and Human Wellbeing
This chapter highlights the importance of conservation for human wellbeing. Nature provides us with ecosystem services vital to our health and wellbeing. However, these services have been taken for granted until now. There is a relationship between biodiversity and ecosystem service delivery; loss of biodiversity leads to losses in the ecosystem service, both in its level and its reliability. Traditionally, nature has been valued at zero, hence decision-makers rarely opt for nature conservation rather than using land for other purposes. It is vital that we value ecosystem services correctly and fully so that the real cost of their loss is realized. Often when the full costs and benefits are assessed, nature conservation turns out to be the most cost-effective and valuable option.
Energy Flow and Food Webs
This chapter studies the flow of energy through ecosystems and the factors that control its movement through different trophic levels. It looks at the feeding relationships in an ecosystem as an intricate web of interactions among species, a view that has important implications for energy flow and ecosystem function as well as for species interactions and community dynamics. Each feeding category, or trophic level, is based on the number of feeding steps by which it is separated from autotrophs. The first trophic level consists of the autotrophs, the primary producers that generate chemical energy from sunlight or inorganic chemical compounds. The second trophic level consisted of the herbivores that consume autotroph biomass as well as organisms that consume dead organic matter, called detritivores. The remaining trophic levels (third and up) contain the carnivores that consume animals at the trophic level below them. Most ecosystems have four or fewer trophic levels.