The resources available for research are always limited. When setting priorities for research funding, governments, industry, and funding agencies must balance the demands of human health, food supply, and standards of living, against the less-tangible benefits of discovering more about the planet's biodiversity. Scientists have discovered almost 2 million species indicating that we have made great gains in our knowledge of biodiversity. However, this knowledge may distract attention from the estimated four-fifths of species on Earth that remain unknown to science, many of them inhabiting our oceans [1], [2]. The world's media still find it newsworthy when new species are discovered [1]. However, the extent of this taxonomic challenge no longer appears to be a priority in many funding agencies, perhaps because society and many scientists believe we have discovered most species, or that doing so is out of fashion except when new technologies are employed. Another symptom of this trend may be that the increased attention to novel methods available in molecular sciences is resulting in a loss of expertise and know-how in the traditional descriptive taxonomy of species [3]. The use of molecular techniques complements traditional methods of describing species but has not significantly increased the rate of discovery of new species (at least of fish), although it may help classify them [4]. At least in Europe, there was a mismatch between the number of species in a taxon and the number of people with expertise in it [5]. Unfortunately, because most species remain to be discovered in the most species-rich taxa [2], [5], [6], [7], there are then few experts to appreciate that this work needs to be done. Evidently, a global review of gaps in marine biodiversity knowledge and resources is overdue.

History of discovering marine biodiversity
Although the economic exploitation of marine resources dates back to prehistoric times, and historical documentation has existed since the third century B.C. with Aristotle's contributions in the Mediterranean Sea (e.g. [8]), the establishment of systematic collections of marine organisms began only during the seventeenth and eighteenth centuries. Global marine biodiversity investigations at these times depended not only on the availability of expertise, but also on foreign policies of the colonial powers of the time. For those reasons, the specimens collected from several regions (e.g., Caribbean, Japan, South America, Africa) were mostly brought to Europe, where they were described, deposited in museum collections, and used for the production of marine biological monographs. These early publications contained descriptions and checklists of many marine species, such as molluscs, crustaceans, fishes, turtles, birds, and mammals (e.g. [9], [10], [11]).

The history of research on marine biodiversity can generally be divided into three periods: early exploratory studies, local coastal “descriptive” studies, and large-scale multidisciplinary investigations and syntheses. These periods vary in timing by different seas and countries. The first exploratory studies in several regions (e.g., South America, Caribbean, South Africa, Pacific Ocean) took place from the mid-1700s until the late-1800s, in association with mainly European, North American, and Russian exploration expeditions, such as the Kamchatka Expedition in the 1740s, James Cook's voyages in the 1770s, the cruise of HMS Beagle in the 1830s, the voyage of HMS Challenger in the 1870s, and the first deep-sea investigations in the Mediterranean Sea [8], [9], [12], [13]. Pioneer investigations on deep-sea organisms were conducted in the Aegean Sea, where Forbes [14] noticed that sediments became progressively more impoverished in terms of biodiversity with increasing sampling depth. The azoic hypothesis proposed by Forbes suggested that life would be extinguished beyond 500 m depth, although a work published 68 years earlier provided indisputable evidence of the presence of life in the Gulf of Genoa at depths down to 1,000 m [15].

The taxonomists who described marine species at these times seldom collected specimens themselves in the field and, therefore, had only second-hand information about the distribution and ecology of the samples they received [4], [8]. Some of the early descriptions of tropical species thus do not even have the locality where the holotype or voucher material was collected (some examples in Chenu 1842–1853). The second period of regional studies was initiated by enhanced availability of research resources (experts, institutes, and vessels) in developing countries around the mid-1900s. The earliest institutions and research stations, many of which continue to operate, were founded in some areas as early as the late 1800s and early 1900s (e.g. [11], [16], [17]). Wide-scale establishment of laboratories in several continents (Europe, New Zealand, North and South America) have only been operational since the 1950s–1960s. The third stage, large-scale multidisciplinary investigations, has evolved since the 1990s, and is related to development and application of modern technologies and implementation of large, multinational research projects. Perhaps the largest of such investigations was the Census of Marine Life (Census).

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A census of marine biodiversity knowledge, resources, and future challenges.

https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.1961.6.1.0099

Marine Algae of the Eastern Tropical and Subtropical Coasts of the Americas

With only about one-sixth of the original coral cover left, most Caribbean coral reefs may disappear in the next 20 years, primarily due to the loss of grazers in the region, according to this latest report, Status and Trends of Caribbean Coral Reefs: 1970-2012. This is the most detailed and comprehensive study of its kind published to date – the result of the work of 90 experts over the course of three years. It contains the analysis of more than 35,000 surveys conducted at 90 Caribbean locations since 1970, including studies of corals, seaweeds, grazing sea urchins and fish.

Status and trends of Caribbean coral reefs : 1970-2012

The South American region
The marine areas of the South American continent extend for almost 30,000 km of coastline and encompass three different oceanic domains—the Caribbean, the Pacific, and the Atlantic. The latitudinal and longitudinal ranges within this region are similarly wide, from 12°N to 55°S, and from 34° to 81°W. Ten countries border on these coasts, each with different research capabilities and taxonomic traditions; therefore, taxonomic knowledge differs among countries. Coastal biodiversity is strongly influenced by the physical and geological history of these coasts. The eastern tropical Pacific region, which encompasses the continental coasts of southern Central America (Costa Rica and Panama) and of northwestern South America (Colombia and Ecuador) is characterized by cliffs alternating with pocket beaches, alluvial and deltaic plains with extensive sandy beaches, well-developed mangrove forests, estuaries, lagoons, and, reefs. It also includes important offshore island systems such as the Pearl and Galapagos islands [1], [2]. The Peruvian coast also is diverse with bays, cliffs, kelp and macroalgal beds, rocky shores and sandy beaches, islands, and peninsulas, as well as wetlands, which include the southernmost limit to the tropical Pacific mangrove ecosystem [3], [4]. The Chilean coast is 4,500 km of mainly rocky shores, but does include some sandy-beach bays with channels and archipelagos toward the south (Patagonian region) [5], [6]. Some of the most diverse ecosystems in Chile are the beds of kelp (Lessonia and Macrosystis) and macroalgae (Gracillaria and Ulva). The combination of the unique oceanographic conditions and coastal heterogeneity in the Chilean coast has resulted in high levels of endemism (near 40%) in many invertebrate groups [5], and several marine invertebrate taxa show latitudinal biodiversity patterns, some of them explained by the presence of Antarctic fauna [7]–[9]. Ecuador, Peru, and Chile are under the influence of the Humboldt upwelling system and subject to high environmental variability caused by the ENSO (El Nino Southern Oscillation) and LNSO (La Nina Southern Oscillation), which cause important changes in community composition and abundance, particularly of the plankton [1], [10].

The Atlantic coast of the South American continent is distinctly different from the Pacific coast. It includes three major rivers (Orinoco, Amazon, and La Plata), which discharge enormous amounts of freshwater and sediment to the ocean, and the coast has an extensive continental platform. Argentina's coast has mostly sandy beaches [6], [11] and some rocky formations located mainly at Mar del Plata and at Peninsula Valdes. At Mar del Plata, these rocky shores are dominated by two mussel species and by a diverse macroalgal community with a clear tidal zonation [12], [13]. The Uruguayan coast is dominated by sandy beaches with a narrow portion of rocky habitats known to sustain a rich biological diversity [14]. Observed variations in community composition and distribution may be related to the salinity gradient caused by La Plata River discharge [15].

The coast of Brazil, extending almost 7,500 km, is under the influence of the warm Brazil Current, the cold Malvinas/Falklands Current, and many rivers and upwelling regions [16]. The warm northern coast, where the Amazon discharges into the ocean, is characterized by a combination of freshwater, estuarine, and marine ecosystems, with diverse but poorly known habitats [17]. The colder southern coast is characterized by a variety of ecosystems, including mangrove forests, seagrass beds, coral reefs, sandy beaches, rocky shores, lagoons, and estuaries. Because of its vastness, extensive areas of Brazil's coast remain unexplored. North of Brazil are Suriname, French Guiana, Guyana, and the Venezuelan Atlantic Front. This area, including about 1,900 km of coastline, is under the strong influence of the Amazon River. Therefore, the typical ecosystems are estuaries, mudflats, sandy beaches, and mangrove forests, which extend along most of the coastline [18]. The Venezuelan Atlantic coast is also under the influence of the Orinoco River, with coastal mudflats and extensive mangrove forests [19].

In this paper, we analyze the status of knowledge of marine biodiversity in five subregions along the Atlantic and Pacific coasts of South America. As most of the information is based in national reports, these subregions were based in the Large Marine Ecosystem boundaries as defined for South America, with a few practical adaptations, based in country political borders. The paper also provides an updated review of ecosystem threats, such as invasive species, and the marine conservation strategies employed by South American countries with access to the coast, excluding the Caribbean coasts of Venezuela and Colombia, as these are included in another paper of this collection [20].

/pdf/marine-biodiversity-in-the-atlantic-and-pacific-coasts-of-1q8pu58qrb.pdf

Marine biodiversity in the Atlantic and Pacific coasts of South America: knowledge and gaps.

Marine biogeographic realms have been inferred from small groups of species in particular environments (e.g., coastal, pelagic), without a global map of realms based on statistical analysis of species across all higher taxa. Here we analyze the distribution of 65,000 species of marine animals and plants, and distinguish 30 distinct marine realms, a similar proportion per area as found for land. On average, 42% of species are unique to the realms. We reveal 18 continental-shelf and 12 offshore deep-sea realms, reflecting the wider ranges of species in the pelagic and deep-sea compared to coastal areas. The most widespread species are pelagic microscopic plankton and megafauna. Analysis of pelagic species recognizes five realms within which other realms are nested. These maps integrate the biogeography of coastal and deep-sea, pelagic and benthic environments, and show how land-barriers, salinity, depth, and environmental heterogeneity relate to the evolution of biota. The realms have applications for marine reserves, biodiversity assessments, and as an evolution relevant context for climate change studies.

/pdf/marine-biogeographic-realms-and-species-endemicity-mmoc2hicgj.pdf

Marine biogeographic realms and species endemicity.

This paper provides an analysis of the distribution patterns of marine biodiversity and summarizes the major activities of the Census of Marine Life program in the Caribbean region. The coastal Caribbean region is a large marine ecosystem (LME) characterized by coral reefs, mangroves, and seagrasses, but including other environments, such as sandy beaches and rocky shores. These tropical ecosystems incorporate a high diversity of associated flora and fauna, and the nations that border the Caribbean collectively encompass a major global marine biodiversity hot spot. We analyze the state of knowledge of marine biodiversity based on the geographic distribution of georeferenced species records and regional taxonomic lists. A total of 12,046 marine species are reported in this paper for the Caribbean region. These include representatives from 31 animal phyla, two plant phyla, one group of Chromista, and three groups of Protoctista. Sampling effort has been greatest in shallow, nearshore waters, where there is relatively good coverage of species records; offshore and deep environments have been less studied. Additionally, we found that the currently accepted classification of marine ecoregions of the Caribbean did not apply for the benthic distributions of five relatively well known taxonomic groups. Coastal species richness tends to concentrate along the Antillean arc (Cuba to the southernmost Antilles) and the northern coast of South America (Venezuela – Colombia), while no pattern can be observed in the deep sea with the available data. Several factors make it impossible to determine the extent to which these distribution patterns accurately reflect the true situation for marine biodiversity in general: (1) highly localized concentrations of collecting effort and a lack of collecting in many areas and ecosystems, (2) high variability among collecting methods, (3) limited taxonomic expertise for many groups, and (4) differing levels of activity in the study of different taxa.

/pdf/marine-biodiversity-in-the-caribbean-regional-estimates-and-3uevi7d6l0.pdf

Aniuska Kazandjian

Papers

Marine Biodiversity in the Caribbean: Regional Estimates and Distribution Patterns