Academic literature on the topic 'Marine photosynthetic organisms'

The phytoplanktons are organisms that have limited locomotion about the current being drift in aquatic environment. Another characteristic of phytoplankton their growth and energy are result about photosynthetic process. It is important to emphasize that the phytoplankton is the main primary producer of aquatic environment, it means that, it is the base the aquatic food chain . The organic material produced by phytoplankton is responsible in provide the material and energy which sustains the growth of fish, crustaceans and mollusks, in marine ecosystems. Because of this, it is important to know the factors that interfere with their accumulation in environments mainly in fishing regions. In this way, this study tries to demonstrate the importance of retention time, often caused by hydrological issues, in the variation of phytoplankton biomass in the estuary of the Patos Lagoon (ELP), in Rio Grande/RS. To do that, we created one model that simulates this environment, using techniques of multi-agent-based simulation and its implementation was done with the NetLogo tool.

The benthic environment refers to the region defined by the interface between a body of water and the bottom substrate, including the upper part of the sediments, regardless of the depth and geographical location. Hence, benthic environments, their organisms, and their ecosystems are highly variable as they encompass the full depth range of the oceans with associated changes in physical and chemical properties as well as differences linked to latitudinal and geographical variation. The effects of ocean acidification on the full range of different benthic organisms and ecosystems are poorly known and difficult to ascertain. Nevertheless, by integrating our current knowledge on the effects of ocean acidification on major benthic biogeochemical processes, individual benthic organisms, and observed characteristics of benthic environments as a function of seawater carbonate chemistry, it is possible to draw conclusions regarding the response of benthic organisms and ecosystems to a world of increasingly higher atmospheric CO2 levels. The fact that there are large-scale geographical and spatial differences in seawater carbonate system chemistry (see Chapter 3), owing to both natural and anthropogenic processes, provides a powerful means to evaluate the effect of ocean acidification on marine benthic systems. In addition, there are local and regional environments that experience high-CO2 and low-pH conditions owing to special circumstances such as, for example, volcanic vents (Hall- Spencer et al . 2008 ; Martin et al . 2008 ; Rodolfo-Metalpa et al . 2010), seasonal stratification (Andersson et al . 2007), and upwelling (Feely et al . 2008 ; Manzello et al . 2008 ) that may provide important clues to the impacts of ocean acidification on benthic processes, organisms, and ecosystems. The objective of this chapter is to provide an overview of the potential consequences of ocean acidification on marine benthic organisms, communities, and ecosystems, and the major biogeochemical processes governing the cycling of carbon in the marine benthic environment, including primary production, respiration, calcification, and CaCO3 dissolution. The depth of the euphotic zone, i.e. the depth of water exposed to sufficient sunlight to support photosynthesis, varies depending on a range of factors affecting the clarity of seawater, including river input and run-off to the coastal ocean, upwelling, mixing, and planktonic production.

Now that we have discussed how assemblages of marine soft sediments are structured, we need to consider functional aspects. There are a few main interrelationships that need to be discussed here— inter- and intraspecific competition, feeding and predator–prey interactions, the production of biomass, and the production and delivery of recruiting stages. Other functional aspects, such as the effects of pathogens and parasites and the benefits of association (mutualism, parasitism, symbiosis, etc.) are of less importance in the present discussion. By function we mean the rate processes (i.e. those involving time) that either affect (extrinsic processes) or are inside (intrinsic processes and responses) the organisms that live in sediments. Hence these include primary and secondary production and processes that are mitigated by the organisms that live in sediments, such as nutrient and contaminant fluxes into and out of the sediment. We begin with the historical development of the field since such aspects are often overlooked in these days of electronic searches for references. Functional studies of ecosystems really began with Lindeman´s classic paper (1942) on trophic dynamics. Rather than regarding food merely as particulate matter, Lindeman expressed it in terms of the energy it contained, thereby enabling comparisons to be made between different systems. For example, 1 g of the bivalve Ensis is not equivalent in food value to 1 g of the planktonic copepod Calanus, so the two animals cannot be compared in terms of weight, but they can be compared in terms of the energy units that each gram dry weight contains. The energy unit originally used was the calorie, but this has now been superseded by the joule (J), 1 calorie being equivalent to 4.2 joules. Ensis contains 14 654 J g-1 dry wt and Calanus 30 982 J g-1 dry wt. The basic trophic system is well understood and can be summarized as we showed earlier in Fig. I.8 which gives the links between various trophic levels and the role of competition, organic matter transport, and resource partitioning. In systems fuelled by photosynthesis (so excluding the chemosynthetic deep-sea vent systems), the primary source of energy for any community is sunlight, which is fixed and stored in plant material, which thus constitutes the first trophic level in the ecosystem.

The nature of the relationships between physical and biological processes in the ocean is subtle and complex. Not only do the physical phenomena create a structure, such as a shallow, mixed layer or a front, within which biological processes may proceed, but they also influence the rates of biological processes in many indirect ways. In the ocean, physical phenomena control the distribution of nutrients necessary for phytoplankton photosynthesis. Places with higher kinetic energy have higher concentrations of planktonic organisms, and that makes the whole food web richer (Mann and Lazier 1996). For example, in the midriff region of the Sea of Cortés (Tiburón and Ángel de la Guarda; fig. 1.2), tidal currents are strong, and intense mixing occurs, creating a situation similar to constant upwelling. Thus, primary productivity is high, and this area supports large numbers of sea birds and marine mammals (Maluf 1983). The Gulf of California is a dynamic marginal sea of the Pacific Ocean and has been described as an area of great fertility since the time of early explorers. Gilbert and Allen (1943) described it as fabulously rich in marine life, with waters fairly teeming with multitudes of fish, and to maintain these large numbers, there must be correspondingly huge crops of their ultimate food, the phytoplankton. Topographically the gulf is divided into a series of basins and trenches, deepening to the south and separated from each other by transverse ridges (Shepard 1950; fig. 3.1). Input of nutrients into the gulf from rivers is low and has only local coastal effects. The Baja peninsula has only one, very small river, near 27°N; rivers in mainland Mexico and the Colorado River have dams that divert most of the water for agricultural and urban use. The gulf has three main natural fertilization mechanisms: wind-induced upwelling, tidal mixing, and thermohaline circulation. Upwelling occurs off the eastern coast with northwesterly winds (winter conditions from December through May) and off the Baja California coast with southeasterly winds (summer conditions from July through October), with June and November as transition periods (Álvarez-Borrego and Lara- Lara 1991).

Blue Carbon, which is carbon captured by marine organisms, has recently come into focus as an important factor for climate change initiatives. This carbon is stored in vegetated coastal ecosystems, specifically mangrove forests, seagrass beds and salt marshes. The recognition of the C sequestration value of vegetated coastal ecosystems provides a strong argument for their protection and restoration. Therefore, it is necessary to improve scientific understanding of the mechanisms that stock control C in these ecosystems. However, the contribution of Blue Carbon sequestration to atmospheric CO2

Blue Carbon, which is carbon captured by marine organisms, has recently come into focus as an important factor for climate change initiatives. This carbon is stored in vegetated coastal ecosystems, specifically mangrove forests, seagrass beds and salt marshes. The recognition of the C sequestration value of vegetated coastal ecosystems provides a strong argument for their protection and restoration. Therefore, it is necessary to improve scientific understanding of the mechanisms that stock control C in these ecosystems. However, the contribution of Blue Carbon sequestration to atmospheric CO2