Juan José Alvarado

Marine Biodiversity in the Caribbean: Regional Estimates and Distribution Patterns

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.

Echinoderm Research and Diversity in Latin America

Latin America (LA) includes all countries in the Americas that speak Spanish or Portuguese; in total it includes 22 countries including Mexico, Central America, the islands of the Caribbean and South America and Haiti (Hispaniola Island, shared with Dominican Republic). This book is divided in 16 chapters and two taxonomic lists with information about presence/absence, bathymetric range and the habitat or substrate where the species have been found. Fourteen chapters deal with studies done in countries, regions or islands. The final chapter has a biogeographical and diversity analysis of the two taxonomic lists. Each country chapter contains six sections. 1. An introduction. 2. A historic account of the investigations on echinoderms. 3. Distributional patterns and diversity. 4. Fishery or aquaculture activities. 5. Threats to echinoderms, and 6. A final section with general conclusions from the review and recommendations for future research to meet the needs of each country. Latin American echinoderm studies started a long time ago, as far back as the 13th century. The most common threats to echinoderms are bad coastal planning, coastal pollution, illegal fisheries, inefficient fisheries management, lack of protection, and lack of baseline studies. A total of 1,539 species (21.8 % of the worldwide species) are included in the taxonomic lists (appendix), with 717 species in the Pacific and 926 in the Caribbean and Atlantic. The richest class is Ophiuroidea followed by Asteroidea. All classes have more species in the Caribbean and Atlantic than the Pacific.

Echinoderm (Echinodermata) diversity in the Pacific coast of Central America

We present a systematic list of the echinoderms of Central America Pacific coast and offshore island, based on specimens of the National Museum of Natural History, Smithsonian Institution, Washington D.C., the Invertebrate Zoology and Geology collections of the California Academy of Sciences, San Francisco, the Museo de Zoología, Universidad de Costa Rica, San José and published accounts. A total of 287 echinoderm species are recorded, distributed in 162 genera, 73 families and 28 orders. Ophiuroidea (85) and Holothuroidea (68) are the most diverse classes, while Panama (253 species) and Costa Rica (107 species) have the highest species richness. Honduras and Guatemala show the highest species similarity, also being less rich. Guatemala, Honduras, El Salvador y Nicaragua are represented by the most common nearshore species. Due to their coastal heterogeneity, Costa Rica and Panama are the richest places, with Panama also being the place where more research has been done. The current composition of echinoderms is the result of the sampling effort made in each country, recent political history and the coastal heterogeneity.

Echinoderm diversity in the Caribbean Sea

The Caribbean is considered a unique biogeographic province, being one of the top five hotspots in the world for marine and terrestrial biodiversity. The echinoderm research on the Caribbean began in the middle of the nineteenth century, and during the first half of the twentieth century most of the species were described. The number of ecological studies increased in the 1970s that continues until today, mostly focused on Diadema antillarum. Based on an extensive review of published records, the Caribbean echinoderm fauna is composed of 433 species, 237 genera, 80 families, 29 orders in five classes, with four endemic species. The richest class is Ophiuroidea with 148 species followed by the class Asteroidea with 116 species. Mexico and Colombia are the richest countries with 182 and 180 species respectively, while Costa Rica and Guatemala are the less diverse with fewer than 50 species. In general terms, the Caribbean is very homogeneous in species composition; however, Colombia and Mexico are the countries more dissimilar in composition with respect to the rest of countries. This semi-enclosed sea represents 6.5% of the total diversity of the phylum worldwide, and is the second most diverse area in tropical America, after Gulf of Mexico. Six species of echinoderms are extracted for commercial use, mostly in Panama, Nicaragua, Colombia, Venezuela and Cuba. However, extraction for the souvenir trade, without any regulation and control, is one of the major threats for some animals—especially the sea star Oreaster reticulatus. Research priorities for this group in the Caribbean include exploration of the deep sea, the Central American region and the Lesser Antilles. Moreover, because of its rich biodiversity, research and conservation efforts have to be directed towards its preservation, avoiding illegal extraction, enforcing controls, and improving coastal zone management.

Eastern Pacific Coral Reef Provinces, Coral Community Structure and Composition: An Overview

Advances in our knowledge of eastern tropical Pacific (ETP) coral reef biogeography and ecology during the past two decades are briefly reviewed. Fifteen ETP subregions are recognized, including mainland and island localities from the Gulf of California (Mexico) to Rapa Nui (Easter Island, Chile). Updated species lists reveal a mean increase of 4.2 new species records per locality or an overall increase of 19.2 % in species richness during the past decade. The largest increases occurred in tropical mainland Mexico, and in equatorial Costa Rica and Colombia, due mainly to continuing surveys of these under-studied areas. Newly discovered coral communities are also now known from the southern Nicaraguan coastline. To date 47 zooxanthellate scleractinian species have been recorded in the ETP, of which 33 also occur in the central/south Pacific, and 8 are presumed to be ETP endemics. Usually no more than 20–25 zooxanthellate coral species are present at any given locality, with the principal reef-building genera being Pocillopora, Porites, Pavona, and Gardineroseris. This compares with 62–163 species at four of the nearest central/south Pacific localities. Hydrocorals in the genus Millepora also occur in the ETP and are reviewed in the context of their global distributions. Coral community associates engaged in corallivory, bioerosion, and competition for space are noted for several localities. Reef framework construction in the ETP typically occurs at shallow depths (2–8 m) in sheltered habitats or at greater depths (10–30 m) in more exposed areas such as oceanic island settings with high water column light penetration. Generally, eastern Pacific reefs do not reach sea level with the development of drying reef flats, and instead experience brief periods of exposure during extreme low tides or drops in sea level during La Nina events. High rates of mortality during El Nino disturbances have occurred in many ETP equatorial areas, especially in Panama and the Galapagos Islands during the 1980s and 1990s. Remarkably, however, no loss of resident, zooxanthellate scleractinian species has occurred at these sites, and many ETP coral reefs have demonstrated significant recovery from these disturbances during the past two decades.

Latin America Echinoderm Biodiversity and Biogeography: Patterns and Affinities

We investigated the current patterns of diversity by country and by class of echinoderms, and analyzed their biogeographical, depth, and habitat or substratum affinities, using the database of the appendix of this book. Traditionally, the area has been divided into five biogeographical Regions and nine Provinces that cover a wide climate range. Currently, the echinoderm fauna of Latin America and Canary islands is constituted by 1,539 species, with 82 species of Crinoidea, 392 species of Asteroidea, 521 species of Ophiuroidea, 242 species of Echinoidea and 302 species of Holothuroidea. Species richness is highly variable among the different countries. The number of species for the countries is highly dependent on its coast length. The echinoderm fauna of the Panamic, Galapagos and the Chilean regions are biogeographically related. Other regions that are closely related are the Caribbean, West Indian, Lusitania and Brazilian. Cosmopolitan species are an important component in all the regions. Affinities between faunas are a consequence of the combination of climatic and trophic factors, connectivity as a function of distance, currents patterns and historical processes. Moreover, different environmental factors would be responsible for the faunal composition and species distribution at different spatial scales. The bathymetrical distribution of the echinoderm classes and the species richness varies according to the depth range and the ocean. Most species occurred at depths between 20 and 200 m. The Caribbean-Atlantic regions are richest in shallow depths, while the Pacific coast has higher values in deeper waters. The domination of each class in each substrate and habitat categories also varies differentially along each coast.

Distribution and diversity of echinoderms (Asteroidea, Echinoidea, Holothuroidea) in the islands of the Gulf of Chiriqui, Panama

Los estudios de equinodermos en el Pacifico Panameno han sido enfocados principalmente en analisis moleculares y evolutivos, y los pocos trabajos ecologicos se han enfatizado en dos especies: Diadema mexicanum y Acanthaster planci. En este trabajo, se describe por primera vez la diversidad (basado en los indices de Margalef, Shannon y Pielou), distribucion y densidad de equinodermos de algunas islas del Golfo de Chiriqui, utilizando una metodologia regional estandarizada para el Corredor Marino de Conservacion del Pacifico Tropical Oriental. Se estudiaron 53 sitios, encontrandose 17 especies de equinodermos: 6 asteroideos, 6 equinoideos y 5 holoturoideos. Los valores promedio de los indices de riqueza de especies, diversidad de Shannon y equidad de Pielou fueron 0,43 ± 0,04, 0,187 ± 0,020, y 0,421 ± 0,035 respectivamente. En promedio se encontro 3 especies y 176 individuos por sitio. Tres especies de equinoideos fueron las mas abundantes: D. mexicanum, Eucidaris thoaursii and Echinometra vanbrunti, con 7909, 771 y 569 individuos respectivamente. A pesar de dichas abundancias, su impacto, al igual que otros organismos coralivoros (e.g., A. planci), es bajo y por el momento no son consideradas como amenazas para los arrecifes de la zona. Los sitios con mayor riqueza y diversidad de especies estan asociados a sitios de mayor diversidad de corales y con una cobertura de coral vivo de moderada a alta. Se sugiere la evaluacion continua de las poblaciones que podrian ser perjudiciales, asi como de las especies que pueden estar bajo extraccion ilegal.

Marine Biodiversity of Eastern Tropical Pacific Coral Reefs

The eastern tropical Pacific (ETP) is an isolated oceanic region exposed to extreme oceanographic conditions, including low salinity, low pH, high temperatures during El Nino, and low temperatures during La Nina and seasonal upwelling. The coral reefs in this region have a relatively limited suite of species compared to other coral reef areas of the world, but much like more diverse reefs the species present interact in complex ways. Here we synthezise the knowledge of taxonomic groups of reef organisms from prokaryotes to vertebrates, including algae, sponges, cnidarians, annelids and other worms, molluscs, crustaceans, echinoderms and fishes. We also present summaries on the biodiversity of associated functional groups and habitats, including (a) reef zooplankton and cryptic fauna, and (b) soft benthic environments, rhodolith beds and mesophotic environments. Several factors that structure the biodiversity of ETP coral reefs are explored, including biological, physical and chemical controls. ETP coral reefs are relatively simple systems that can be used as models for studying biodiversity and interactions among species. We conclude this review by highlighting pressing research needs, from very basic inventories to more sophisticated studies of cryptic assemblages, and to investigations on the impacts of natural and anthropogenic effects on ETP coral reef biodiversity.

Central America Echinoderms: Diversity, Ecology and Future Perspectives

Central America is a region with a high biological diversity, not only in its terrestrial part, but also in its marine component. This is the result of a rich geological history that has caused the exchange and isolation of fauna and flora. The richness of ecosystems and coastal morphologies allow the presence of various groups of organisms, and among them are the echinoderms. Investigation of echinoderms in the region goes back to 1867 when the first publication appeared. Research on echinoderms in Central America can be divided into two periods. The first period consists mainly of expeditions from Europe and the United States (1860–1960). The second period involved the formation of local scientists and the establishment of research centers in the region (1960–present). Two hundred and twenty-nine publications have been published on Central America echinoderms. The majority focused on ecology, taxonomy and evolution. Panama, Belize and Costa Rica are the countries where most of the research has been done. In this chapter we reviewe and describe the most important results of those investigations, with the exception of Panama, which is considered by Coppard and Alvarado (Chapter 4). Four hundred and sixteen species of echinoderms are reported, 214 species in the Caribbean and 207 species in the Pacific. Ophiuroidea is the most diverse class with 123 species, followed by Echinoidea (94 species), Asteroidea (80 species), Holothuroidea (80 species), and Crinoidea (18 species). The number of species is approximately 6 % of the total known echinoderms worldwide. Most of the investigations have been focused on echinoids and ophiuroids, with very little work on the other groups. The main threats to this phylum are environmentaal deteriorations by natural processes, and above all, by rapid coastal development. In addition, illegal fishing, by-catch and the lack of protection and coordination from the authorities are affecting the sea cucumbers and sea stars populations. An increase in research is recommended for Guatemala, Honduras, El Salvador and Nicaragua, through programs of regional exchange and by the development of specialists in each one of these countries. Moreover, emphasis must be given to developing new lines of research to fill the gaps in knowledge of various groups and ecosystems.

Coral Reef Bioerosion in the Eastern Tropical Pacific

Bioerosion, the weakening and erosion of hard substrates by boring, etching, and grazing organisms, is a major structuring force on coral reefs of the Eastern Tropical Pacific (ETP). Bioerosional processes are the main source of reef erosion, and facilitate recycling of reefal carbonate. In healthy reefs, a dynamic balance exists between destructive (i.e. bioerosion) and constructive (i.e. bioaccretion) processes, allowing for maintenance and growth of reef frameworks. In changing environments, however, bioerosion rates can exceed those of coral calcification, leading to reduced reef development and the destruction of reef frameworks. In the ETP, high rates of bioerosion are promoted by nutrient-rich upwelling and high primary productivity conditions, recurrent coral bleaching and mortality events, and a chemical environment characterized by high-pCO2 and low aragonite saturation state. Here we examine bioerosion in ETP coral habitats and the variable roles of reef-dwelling bioeroder taxa: microbial euendoliths (microendoliths), sponges, polychaetes, sipunculans, crustaceans, molluscs, echinoids, and reef fishes. Among these agents of bioerosion, sponges, sipunculans, bivalves, and echinoderms have been relatively well studied in this region, while information is currently lacking or limited for microendolith assemblages, polychaetes and reef fishes. The frequency of coral invasion by clionaid sponges (e.g., Cliona vermifera and Thoosa mismalolli) is variable between ETP coral habitats. Dense boring sponge assemblages can lead to high rates of carbonate losses exceeding those of bioaccretion. Boring bivalves (i.e., species of Lithophaga and Gastrochaena) are very abundant on many actively accreting reefs and are generally more prominent contributors to reef erosion in the ETP than in other regions. Sea urchins are by far the most destructive grazers of coral substrates in habitats where abundant. Following ENSO-associated coral mortality events, intense bioerosion by sea urchins has impeded coral recovery and compromised reef health at many eastern Pacific sites. This chapter reviews factors important in ETP bioerosion, and current knowledge of bioeroder populations in the region.