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INTRODUCTION TO THE GREATER CARIBBEAN

  1. THE GREATER CARIBBEAN
    1.1 Terrestrial and marine topography


  2. CLIMATE

    2.1 Rainfall and Rivers

    2.2 Sea Surface Temperatures

    2.3 The wind regime and hurricanes


  3. OCEANOGRAPHY

    3.1 Tides

    3.2 Surface ocean currents

    3.3 Salinity

    3.4 Ocean productivity

    3.5 Ocean acidity


  4. MARINE HABITATS

    4.1 Sand and mud shoreline habitats

    4.2 Mangroves

    4.3 Rocky shores and reefs

    4.4 Coral reefs

    4.5 Seagrasses


  5. THE SHOREFISH FAUNA OF THE GREATER CARIBBEAN

    5.1 Identification guides

    5.2 Global online resources about shorefishes

    5.3 Systematic order in which fishes are arranged here

    5.4 Names of fishes (scientific and common names)


  6. BIOLOGY AND ECOLOGY OF GREATER CARIBBEAN SHOREFISHES

    6.1 Use of environments and habitats

    6.2 Reef associated fishes

    6.3 Soft-bottom fishes

    6.4 Pelagic fishes

    6.5 Fishes of environments with different salinities

    6.6 Depth distribution patterns

    6.7 Fishes dietary groups

    6.8 Modes of reproduction

    6.9 Longevity and size


  7. MARINE BIOGEOGRAPHY

1. THE GREATER CARIBBEAN

We cover the shorefish fauna of the marine biogeographic region known as the Greater Caribbean (GC), which traditionally has been thought to encompass the continental shelf from the mid-east coast of Florida in the north (~ 29°N), through all or part of the Gulf of Mexico, south then east along the coast of Central America and northern South America to about Trinidad. The GC also includes all the offshore islands in that area: Bermuda, the Bahamas, the Greater and Lesser Antilles and the oceanic islands of the western Caribbean.



Fig 1. Terrestrial Topography of the Greater Caribbean


1.1 Terrestrial and Marine TopographyGeographically the GC is very complex due to the winding nature of the continental coastline and the large number of islands of greatly varying sizes (Fig 1). Habitat available to shorefishes in different parts of the GC is determined by variation in the extent of shallow (<200m deep) continental and insular shelves. There are large expanses of such shelf between Nicaragua and Jamaica, on the broad shelf north of the Yucatan Peninsula and in the northern and eastern Gulf of Mexico, and the large insular shelf system of the Bahamas archipelago (Fig 2).



Fig 2. Submarine topography of the Greater Caribbean (NASA).






2. CLIMATIC VARIATION IN THE GREATER CARIBBEAN

2.1 Rainfall and Rivers of the Greater Caribbean: The highest rainfall areas in the Greater Caribbean are in the southwest Caribbean (southwest Colombia, western Panama, Costa Rica, Nicaragua) and in Guatemala (Figs 3&4). Inland areas of high rainfall in western Colombia and the Orinoco drainage also affect southern coastal areas. The coastal areas of the rest of the region have moderate to low rainfall.




Fig 3. Regional Rainfall .


Fig 4. Regional Rainfall on land.


There are large rivers that drain into the GC at the eastern and western ends of the northern coast of South America and along the coast of most of the Gulf of Mexico (Fig 5). Those South American rivers have catchments in high rainfall areas and have large outflows. Due to its narrowness the Central American Isthmus has only small rivers draining into the western Caribbean.



Fig 5. River catchments of the Greater Caribbean.


2.2 Sea Surface Temperature (SST) variation throughout the Greater Caribbean: In summer the entire Greater Caribbean experiences tropical SST conditions. Almost all of the Caribbean is tropical year round, except for inshore areas with small winter upwellings along the northern coast of South America. In winter the Gulf of Mexico becomes distinctly subtropical, and inshore along the northern half of that Gulf temperatures drop as low as 100C. The flow of warm water northwards from the Caribbean via the Loop and Florida currents keeps northern Cuba and the Florida keys quite warm during winter. The northern Bahamas and Bermuda are the coldest areas outside the Gulf of Mexico during winter.




Fig 6. Seasonal variation in SST in the GREATER CARIBBEAN (RSMAS)








Fig 7. Seasonal change in average surface wind speed in the Neotropics (NASA)














2.3 Winds of the Greater Caribbean: As can be seen from Fig 7, average wind speeds are moderate in most of the region, and noticeably higher than speeds in most of the Tropical Eastern Pacific, on the western side of the Central American Isthmus. There is one area of consistently high wind activity in the GC, off the coast of Colombia where a high mountain range (the Sierra Nevada) extends very close to the coast (see Fig 1). Wind levels change seasonally in the GC, with more activity during the winter, when prevailing north-east trade winds blow most strongly and consistently over the entire region.




















Fig 8. Neotropical hurricane tracks since the 1850s (NASA)




Fig 9. A hurricane in the Gulf of Mexico (NASA)














Hurricanes: Hurricanes regularly pass through the northern 90% of the Greater Caribbean (Fig 8). Only the northern coast of South America and the southwest corner of the Caribbean are largely and entirely, respectively, exempt from Hurricane passage. The general track is semicircular, westwards through the southern Caribbean, then northwest towards the Gulf of Mexico then northeast into the North Atlantic. Hurricanes can be generated as far east as the Cape Verde islands in the east Atlantic or as far west as the Gulf of Mexico, and anywhere in between.













Fig 10. Tidal regimes of the Greater Caribbean




Fig 11. Global variation in the strength of the major tidal component (NASA)











3 OCEANOGRAPHY



















3.1 Tidal regime: Tidal regimes vary around the globe, from those with two tidal cycles per 24hr period (semidiurnal tidal regime), to those with 1 per day (diurnal tidal regime), to sites with various types of mixtures of both. The nature of the tidal regime varies in different parts of the GC, with most of the region experiencing mixed tides, and the smallest areas with semidiurnal tides (Fig. 10). The continental shorelines to the north and south also have semidiurnal tides. Seasonal variation in GC tidal regimes includes variation in the amplitude of spring and neap tides, in the timing of the occurrence of high and low diurnal tides, and in the relative sizes of the 2 semidiurnal high tides of the same day. Tidal ranges are small throughout the Caribbean and Gulf of Mexico, typically much less than 1m (Fig 10).





















3.2 Surface Ocean Currents of the Greater Caribbean: The northern and southern continental limits of this region are not well defined because warm ocean currents enter it from the south and exit up the southeast US coast, carrying tropical fish northwards as well as connecting the fauna of the GC to that of Brazil. Warm water from the hump of Brazil flows northwest along the coast of South America, first as the North Brazil Current then as the Guiana Current. The flow of the latter splits, with some of it feeding into the southeast corner of the Caribbean and flowing northwest through that sea as the Caribbean Current (Fig 12). The remainder flows north the northwest along the eastern edge of the Antilles as the Antilles Current. There is a large permanent gyre in the southwest Caribbean, the Colombia-Panama Gyre. When the Caribbean Current reaches the northeast corner of the Caribbean it exits to the Gulf of Mexico as the Yucatan Current. This in turn feeds the Mexican Current along the western edge of the Gulf of Mexico, while the main part of its flow curves around to the north then southeast as the Loop Current. This turns eastward between Florida and Cuba as the Florida Current then up the southeast coast of the US as the Gulf Stream. The Gulf Stream, which is fed by both the Florida Current and Antilles Current turns northeast towards Europe halfway up the east coast of the US at about 350N latitude.



Fig 12. Surface Ocean Currents of the Greater Caribbean (RSMAS)

GC = Guyana Current; CC = Caribbean Current; AC = Antilles Current; CPG = Colombia-Panama Gyre; YC = Yucatan Current; MC = Mexican Current; LC = Loop Current; FC = Florida Current; GS = Gulf Stream








Fig 13. Global variation in average salinity




Fig 14. Short-term variation in salinity in the Greater Caribbean area (Aquarius: NASA)
Animation at: http://www.youtube.com/watch?v=zUZHMbZuWVQ



3.3 Ocean salinity throughout the Greater Caribbean: Much of the Greater Caribbean has consistently high salinity (Fig 13.) Outflows from the large rivers that drain the northern gulf of Mexico (Mississippi) and northeastern South America (the Orinoco) produce large areas of reduced salinity, particularly in the southeastern corner of the Caribbean. This situation contrasts strongly with the reduced salinity that strongly affects the entire southern two thirds of the Tropical Eastern Pacific, on the western side of the Central American Isthmus. See NASA animation at http://www.youtube.com/watch?v=zUZHMbZuWVQ











































































Fig 15. Upwelling systems in the Greater Caribbean: A Sea Surface Temperature; B Productivity










3.4 Upwelling systems in the Greater Caribbean:Upwelling systems bring colder subsurface water rich in nutrients to the surface, where they produce increases in ocean productivity. Hence they are visible to satellites as relatively cold areas that have high concentrations of chlorophyll (Fig 15). Upwelling systems in the Greater Caribbean are relatively small in comparison to the three large seasonal upwelling areas off the Pacific coast of Central America. There are a series of half a dozen systems of varying sizes along the northern coast of South America between eastern Venzuela and central Colombia. There is a substantial system off the northern tip of the Yucatan Peninsula, some small scale activity in the western and northwest Gulf of Mexico, and along the edge of the continental shelf off the south east US. Most are produced by wind-driven currents, while that on the SE US shelf is produced by the flow of the Gulf Stream.






















3.5 Natural ocean acidity levels in the Greater Caribbean:Seawater is alkaline, with a natural range of variation in pH from 8.0-8.3. Ocean pH varies considerably at large spatial scales around the globe. Naturally reduced pH (acidification) within this range is associated with coastal upwelling systems. Large scale natural pH reductions are evident in the Tropical Eastern Pacific, where there are large upwelling systems, but not in the Greater Caribbean in part because the upwelling systems are weaker and affect much smaller areas (Fig 16).




Fig 16. Global variation in surface pH of the ocean (WHOI)




4 MARINE HABITATS OF THE GREATER CARIBBEAN




4.1 Sand and mud shorelines: Soft shorelines consisting of sandy and muddy substrata are a major habitat type in much of the continental shore and some of the larger offshore islands, particularly Cuba and the Bahamas. Virtually the entire continental shoreline north of Costa Rica is comprised principally of soft bottoms (Fig 17).




Fig 17. Areas of predominantly sand and mud shorelines in the Greater Caribbean.


4.2 Mangroves: Mangroves represent another important habitat element in the more tropical parts of the Greater Caribbean, one that is developed in association with soft-bottom shorelines. Mangroves are extensively developed in southern Florida, the southern Gulf of Mexico, most of Central America, Cuba and the Bahamas, as well as northeastern South America (Fig 18).




Fig 18. Coastlines of with large mangrove formations in the Greater Caribbean.


4.3 Rocky shores and reefs: Reefs comprise not only emergent coral reefs but also rocky shores and submerged coral reef and hard-bottom areas. Rocky shorelines are virtually absent from the northern two thirds of the continental shore, and only become common along the northern coast of South America. Reefal shorelines and surface reefs are common in the islands. Submerged reef areas and hard-bottoms that support reef-fish populations are particularly important habitat in the Gulf of Mexico and southeastern USA, representing almost 40% of the substrate on the west Florida shelf. It is not known how extensive deeper reef areas are on the large continental shelf east of Nicaragua and the island shelf areas in the central Caribbean (Fig 19).




Fig 19. Areas of rocky and coral shorelines and reefs in the Greater Caribbean


4.4 Coral Reefs: Coral reefs constitute a major habitat type in the central part of the Greater Caribbean, with about 20,000 km2 present. This contrasts to the situation on the western side of the central American isthmus, where coral reefs are very poorly developed. Reduced aragonite carbonate levels due to relatively high pH produced by large upwellings likely are a major factor contributing to this paucity of structural reefs there. In the Greater Caribbean most of the eastern two thirds of the northern coast of South America is affected by small upwellings, and coral reefs are poorly developed along that coast. The central part of the region, which lacks upwellings, contains an abundance of coral reefs, particularly on the central and outer parts of the continental shelves and around the islands. Except in the Florida Keys, coral reef development is very limited in most of the Gulf of Mexico, particularly in the north, where there are only a few small submerged reefs and coral pinnacles along the outer edge of the shelf.



Fig 20. Coral reef distribution in the Greater Caribbean (UNEP_WCMC).


4.5 Seagrasses: Seagrasses represent another major habitat component for shorefishes in the Greater Caribbean and are found throughout the region. There are large areas in Florida, the Yucatan peninsula and Central America, and in Cuba (Fig 21).



Fig 21. Seagrass areas in the Greater Caribbean


5 THE SHOREFISH FAUNA OF THE GREATER CARIBBEAN

This information system covers 1694 species (in 612 genera and 171 families). Of those 1,577 are native to and resident in the Greater Caribbean and are found in shallow (above 100 m depth) areas of the continental and island platforms, or in near-shore pelagic environments. The native shallow-water residents include 703 species endemic to the Greater Caribbean.

5.1 Major modern identification guides to Greater Caribbean shorefishes:Most of the general identification guides to GC shorefishes are aimed at a particular part of that area. Those include Bohlke & Chaplin’s (1968) Fishes of the Bahamas and adjacent waters; Hoese & Moore’s (1977) Fishes of the Gulf of Mexico: Texas, Louisiana & adjacent waters; Robins et al’s 1986 A Field Guide to the Atlantic Coast Fishes of North America; Smith-Vaniz et al’s 1999 Fishes of Bermuda, McEachran & Fechelm’s two volume (1998 & 2005) Fishes of the Gulf of Mexico; and Cervigon’s 6 volume ( 1991-1999) Los Peces Marinos de Venezuela. There have been few truly regional guides that effectively cover the entire GC. Among them are Randall’s (1968) Caribbean Reef Fishes (with subsequent revisions); Smith’s (1997) Aubdubon Field Guide to Tropical Marine Fishes of the Caribbean, Gulf of Mexico, Florida, the Bahamas and Bermuda. In 2002 FAO produced an updated, three volume guide to The Living Marine Resources of the Western Central Atlantic that covers fishes, invertebrates and marine reptiles of the entire GC. Humann & Deloach published a popular photographic guide to reef fishes of the GC, Reef fish identification: Florida, Caribbean, Bahamas, in 1989, with several updated editions since then. Other comprehensive popular guides with more limited geographic coverage include Kells and Carpenter’s (2011) A Field Guide to Coastal Fishes from Maine to Texas, which includes many excellent paintings of fishes in lieu of photographs.

5.2 Global online resources about shorefishes: Major online resources that effectively cover different aspects of the region's fishes via information on individual species, include William Eschmeyer's Catalog of Fishes, at www.calacademy.org/research/icthyology/catalog, which provides comprehensive up to date information on the systematics of fishes and FishBase [ www.fishbase.org ], which summarizes information from other sources on a variety of aspects of the biology of fishes; the International Taxonomic Information System, ITIS (http://www.itis.gov ), which covers the scientific names of fishes. Both OBIS, the International Biogeographic Information System (http://www.iobis.org ) and GBIF, the Global Biodiversity Information Facility ( www.gbif.org ) aggregate and make available information on georeferenced databases of collection records of fishes from individual museums and research organizations.

5.3 Systematic order in which fishes are arranged:The fishes are presented in phylogenetic or systematic order by family (the scientific names of which end in -idae); with the most primitive fishes presented first followed by more recently evolved forms. We follow the classification and sequence of families presented in J.S Nelson's 4th edition (2006) of Fishes of the World. The different genus pages within each family appear alphabetically by scientific name. as do the different species pages within each genus. The Systematic Tree in The Fishes section indicates each species position in a simplified systematic hierarchy that includes only 4 levels: Order, Family, Genus and Species.

5.4 Names of Fishes:

5.4.1 Scientific names:Many of the fishes found in the Greater Caribbean were given their names by ichthyologists in the latter half of the 19th century or the first half of the twentieth century. In some cases the same fish was given a different scientific name by different researchers. By the Law of Priority, the oldest name is the accepted one, provided it is binomial, was accompanied by a description, and was published at the scientific work that started our current system of biological nomenclature (on or after 1758 with the 10th edition of Carl Linnaeus' Systema Naturae). Subsequent, invalid names for previously described organisms are called synonyms. Most of the problems involving synonyms have been sorted out, but some older names are still being discovered, which means they must replace names in current usage. Because The Catalog of Fishes by William Eschmeyer of the California Academy of Sciences provides excellent coverage of this aspect for our fishes, we only occasionally mention synonyms. Here we follow names as presented in ITIS, The International Taxonomic Information System which provides information that supplements that in the Catalog of Fishes, and makes decisions about valid names. The scientific name is the name in two parts, the first being the genus name and the second the species name. Rarely three names are used, in the case of subspecies. This is immediately followed by the name of the author(s) who gave the fish its scientific name and the year in which the description was published. If the author's name is in parentheses, it indicates that the fish was originally placed in a genus that is different from the one that is currently accepted. A few species treated here still lack scientific names, because they have not been formally described; these are indicated by "species A, B etc", following the genus name.

5.4.2 Common names: The common names of fishes used here have been taken from a variety of sources. In many cases they are names that have been previously published in other books (e.g the FAO volumes). ITIS and the American Fisheries Society’s (2012; 6th edition): Common and scientific names of Fishes from the United States and Mexico. Fishes’ common names vary greatly from one country to the next, and even within different parts of the same country. No attempt has been made to fully cover this variation.

6 BIOLOGY AND ECOLOGY OF GC SHOREFISHES

6.1 Use of environments and habitats:The fishes included here are mainly (95.5%) restricted to inshore environments, including not only rocky and coral reefs and there immediate surroundings, but also soft (sand and mud) habitats in estuaries and beaches as well as in water extending well down the continental shelf. Species found on either reefs or soft bottoms exhibit precise habitat preferences that are dictated by a combination of factors including the availability of food and shelter, and various physical parameters such as salinity, depth, water clarity, currents, and wave action, as well as the precise nature of the bottom.

6.2 Reef-associated fishes: The majority of inshore fishes in the region likely to be encountered by divers and anglers are associated with what can be broadly defined as reef habitats. These include rocky shores and submerged rock reefs as well as coral reefs and hard bottoms (low relief rocky bottoms). Rock outcrops and ledges provide necessary shelter and a source of benthic invertebrates and algal growth, important dietary components for many reef fishes. Rocky reefs often have a dense covering of various types of seaweed, which provides additional shelter for a variety of small fishes. About 49.4 % of the regional fauna comprises bottom living fishes found in association with reefs. Some of the more prominent families found on rocky reefs include moray eels, groupers, snappers, grunts, damselfishes, wrasses, parrotfishes, blennies (three families), gobies, and surgeonfishes.

6.3 Soft-bottom fishes:Another large and important segment of the TEP fish fauna is associated with soft bottom habitats, which range from clean white sand in clear waters to soft thick mud, characteristic of turbid bays and estuaries, to mangroves and seagrass beds. Although this habitat is often considered to be low in fish diversity, about 60.9% of the species treated here live in such habitats. The soft bottom community includes such fishes as rays, snake eels, catfishes, lizardfishes, croakers, sand stargazers, and flatfishes.

6.4 Water-column fishes:The third most important group of fishes live in the water column above the substratum, over shallow reefs and soft-bottoms as well as the open ocean. These species constitute about 26.6% of the species included here. These include jacks, anchovies, herrings, and silversides, flyingfishes, tunas and billfishes, as well as a smattering of members from many other families.

6.5 Use of environments of differing salinities:Almost 69.6% of the shorefish fauna comprise species that are found only in marine (i.e.full salinity) environments, while another 29.4% occur in estuarine (reduced salinity) as well as marine situations. Only 7.5% are non-marine species (which do not enter full salinity environments), and only 12.5% enter freshwater. A few of the fishes included here (6.4%) are basically freshwater fishes that occasionally enter brackish water, or whose juveniles are encountered in brackish water.

6.6 Depth distribution patterns:Most of the regional fauna considered here lives in fairly shallow water – 42.3% of species reach the surface, the depth ranges of 71.2% extend to within 5 m of the surface, and only 12.1% do not come above about 50 m. The lower limit of the depth ranges of 38.6% of the species terminate at about 30 m, with only 48.5% occurring down to 50 m and 38.7% below 100 m.

6.7 Fishes dietary groupings:The great majority of Greater Caribbean shorefishes are carnivores of one type or another: 79.1% of the species have such a diet, which includes items ranging from tiny benthic mollusks, worms and crustaceans to sharks, whales and marine birds. The next most abundant group comprises species that consume plankton (either exclusively or with a mix of non-planktonic animals): 28% of the fauna. Bottom feeding omnivores and herbivore/detritivores are relatively uncommon, constituting only about 8.7% and 6.7% of the fauna, respectively.

6.8 Modes of reproduction:The diversity of shore fishes found in the GC is reflected in a wide variety of reproductive habits. The great majority of shorefishes treated here are egg layers that employ external fertilisation. Relatively few species (12.5% of those included here) bear live young that are prepared to fend for themselves at birth. These include most of the sharks and rays, but very few bony fishes: the brotulas and two genera of weed blennies.

Most shorefishes use one of two patterns of egg-laying reproduction. Females of many fishes, including the highly visible wrasses and parrotfishes, scatter relatively large numbers of small, positively buoyant eggs into open water where they are summarily fertilized by the male. Of the species included here 53.6% reproduce in this manner.

The spawning event is typically preceded by nuptial chasing, temporary color changes, and courtship displays in which fins are erected. This behavior is generally concentrated into a short period of the day, often at sundown or shortly afterwards, or is related to the stage of the tidal cycle. This pattern is seen in diverse groups such as lizardfishes, angelfishes, wrasses, parrotfishes, and boxfishes. Typically either pair or group spawning (the latter involving a single female and multiple males) occurs in which the participants make a rapid dash towards the surface, releasing their gonadal products at the apex of the ascent. The fertilised eggs float near the surface and are dispersed by waves, winds, and currents. Hatching occurs within a few days and the young larvae are similarly at the mercy of the elements. Older larvae, however, are good swimmers and have considerable control over their movements. Recent studies of the daily growth rings found on the ear bones (otoliths) of reef fishes indicate that the larval stage generally varies from about 1-8 weeks depending on the species involved. The extended pelagic larval period accounts for the wide dispersal of many reef species.

The second major reproductive pattern (exhibited by 29.5% of shorefish species in the TEP fauna) involves fishes that lay their eggs on the bottom, frequently in rocky crevices, empty shells, sandy depressions, or on the surface of invertebrates such as sponges, corals, or gorgonians. These include the skates and a few of the sharks, which produce large benthic eggs in horny egg cases. Among the best known fishes in this category are the damselfishes, blennies, gobies, and triggerfishes. These fishes often prepare the surface prior to egg deposition by cleaning away detritus and algal growth. Bottom spawners also exhibit elaborate courtship rituals which involve much aggressive chasing and displaying. This behavior has probably been best studied amongst the damselfishes. In addition, one or both parents may exhibit a certain degree of nest-guarding behavior in which the eggs are kept free of debris and guarded from potential egg feeders such as wrasses and butterflyfishes.

A more specialized mode of parental care is seen in cardinalfishes and sea-catfishes, in which the male broods the egg mass in its mouth. Similarly, male pipefishes and seahorses brood their eggs on a highly vascularised region of the belly or underside of the tail. Only 4.3% of our region's fishes reproduce using brooded eggs. As a rule the eggs of benthic nesting and oral-brooding fishes are less numerous, larger, have a longer incubation period, and are at a more advanced developmental stage when hatched, compared to the eggs and larvae of pelagic spawning fishes.

6.9 Longevity and size:There is little information on the longevity of most eastern Pacific reef fishes. Perhaps one of the longest life spans is that of the Lemon Shark, Negaprion brevirostris, which may reach 50 years or more. Most of the larger reef sharks probably live at least to an age of 20-30 years. In general the larger reef fishes such as groupers and snappers tend to live longer than smaller species in the same family or genus. However, small snappers can live as long as much larger groupers. The largest grouper in the western Atlantic is the Goliath grouper (Epinephelus itajara), which reaches 2.5m, 363 kg and lives up to 37 years.Whatever information is available on the maximum size of each species, from the literature as well as our personal experience, is distilled to maximum known total length in both the text and database. A few data is also presented (in the species pages) on maximum total weights when that is known. Most of the species in the shorefish fauna are small: 30.3% are 10 cm or less and 56.5% 25 cm or less. Large species of fishes are uncommon: only 12% are 1 m or longer, and only 4.7% 2 m or longer.

7 MARINE BIOGEOGRAPHY OF THE GREATER CARIBBEAN

The Tropical West Atlantic (TWA), which spans about 600 of latitude, from the southeast US to Brazil, includes two regional centers of species richness and endemism for reef fishes and other reef organisms: the Greater Caribbean and Brazil. The Caribbean and Brazilian reef areas are separated by a ~1200km wide expanse of coastline and inner shelf that is almost entirely free of habitat suitable for reef organisms. The mud, sand and mangrove habitats inshore in that zone are produced by the outflows of large rivers, the largest being the Orinoco in the north and the Amazon in the south. While those two reefal regions each have a substantial proportion of endemic species most of the species found in the TWA are shared between them. The Greater Caribbean is the high diversity heart of the TWA as it has about twice as many species and twice the level of endemism as Brazil. Among the Greater Caribbean shorefish fauna, 46% live on mud and sand bottoms, 39% are reef fishes, and 18% are pelagic species.

Here we cover 1,694 species, 1,577 of them shallow water (found shallower than 100 m depth) shore fishes. With 703 species of shallow-water endemic shorefishes the Greater Caribbean has a substantially lower rate of endemism (45%) than the Tropical Eastern Pacific, where the rate is 78%. Reef fishes of the GC have the highest rate of endemism (60%) and the pelagics the lowest (18%), while the soft-bottom fishes are in between (46%).




Fig 22. Eight schemes for the biogeography of the Greater Caribbean


We recently tested those eight schemes. To do so we divided the Caribbean and surrounding areas into 45 small parts and compared patterns of similarity in faunal composition (species presence) in each of those parts. This analysis was based on information on the geographic ranges of species that is included in the databases used by this website. That faunal-similarity analysis produced a new arrangement for the Greater Caribbean. First (Fig. 23) it showed that the GC is bigger than usually thought by most modern authors, extending as far north as Cape Hatteras (350N) and as far south as Guyana (70N) and perhaps further. This large area of the Greater Caribbean reflects the fact that that all of it is heavily dominated by tropical species. Second it showed that the GC is divided into three major “provinces” each with a distinctively different fauna: (1) a northern province comprising all of the continental Gulf of Mexico and Florida; (2) a central province that includes Central America (Mexico to Panama) and all the offshore islands (Bermuda, the Bahamas, the Antilles and the western Caribbean atolls); and (3) a southern province that comprises all the continental coastline of northern South America. Although each province has a distinctive fauna, the wide distributions of most species binds those areas together to form the Greater Caribbean: at least 85% of the species in each province are found in one or both the other two provinces.




Fig 23. Biogeography of the shorefishes of the Greater Caribbean


These differences in provincial faunas relate to marked differences in the environments of each: The Southern Province is eutrophic. Its coastal waters are productive and relatively rich in nutrients produced by a series of upwellings scattered along most of the northern coastline, and from outflows of large rivers in western Colombia and eastern Venezuela, as well as from the Gulf of Venezuela in the center. As a result of this low salinity, upwelling and high-nutrient state, coral reefs are relatively uncommon in the southern Province, where reef-fish habitat largely comes from rocky shores. The marine environment of this province has been eutrophic for many millions of years. This has shaped the composition of its shorefish fauna , which is similar to that of eutrophic, upwelling-dominate areas in the Tropical Eastern Pacific. The Central Province is relatively oligotrophic, i.e. with waters poor in nutrients. This reflects the absence of significant upwelling systems, and of large rivers. Due to the narrowness of the central American isthmus, and the relatively small sizes of the islands, river catchments and river outflows are small. Low aquatic nutrients and high temperatures facilitate the development of numerous coral reefs throughout that province, which in turn has affected the nature of its fish fauna. The Northern Province has distinctly subtropical water temperatures, with average temperatures lower than anywhere in the central province except the northern Bahamas and Bermuda. Most of this region is eutrophic, due to upwellings in the southern and northwest Gulf of Mexico, and the southeast US, and large river inputs around most of the Gulf of Mexico. Coral reefs are well developed only in the Florida Keys, which are bathed by the warm, salty, oligotrophic flow of the Florida Current from the Caribbean. Elsewhere in that province coral reef development is poor, due to low winter temperatures, upwellings and river outflows. Environmental differences between the three provinces are well summarized by an analysis of global marine shelf environments that compared similarity of grid-squares in temperature, salinity and productivity (due to eutrophication). As can be seen in Fig 24 the northern province has the most heterogeneous environment and one that is most different from environments in most of the rest of the Greater Caribbean. The central province has the most uniform environment except for the northern Bahamas and Bermuda, due to the low winter temperatures in both. The southern province is also somewhat heterogeneous, but that is less evident due to its small size and restriction to a coastal zone with a narrow continental shelf.




Fig 24. Similarity in the marine environments of different parts of the Greater Caribbean.