Fernando A. Zapata

Global human footprint on the linkage between biodiversity and ecosystem functioning in reef fishes.

A global survey of reef fishes shows that the consequences of biodiversity loss are greater than previously anticipated as ecosystem functioning remained unsaturated with the addition of new species. Additionally, reefs worldwide, particularly those most diverse, are highly vulnerable to human impacts that are widespread and likely to worsen due to ongoing coastal overpopulation.

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.

The Mid‐Domain Effect Revisited

We revisit the proposition that boundary constraints on species’ ranges cause species richness gradients (the mid‐domain effect [MDE] hypothesis). In the absence of environmental gradients, species should not retain their observed range sizes as assumed by MDE models. Debate remains regarding the definition of domain limits, valid predictions for testing the models, and their statistical assessment. Empirical support for the MDE is varied but often weak, suggesting that geometric constraints on species’ ranges do not provide a general explanation for richness gradients. Criticism of MDE model assumptions does not, however, imply opposition to the use of null models in ecology.

Condiciones oceanográficas en isla Gorgona, Pacífico oriental tropical de Colombia

RESUMEN. La zona de influencia costera de isla Gorgona es un area marina protegida localizada en el Pacifico Oriental Tropical (POT) de Colombia. Aunque alberga uno de los arrecifes coralinos mas desarrollados del POT, la caracterizacion de las condiciones oceanograficas superficiales locales y su variabilidad temporal y espacial han sido escasamente abordadas. Para incrementar el conocimiento sobre la variabilidad de la temperatura y la salinidad en esta localidad se realizaron registros sistematicos de estas variables durante cuatro periodos (septiembre 2005, diciembre 2005, marzo 2006 y junio 2006), se instalaron sensores de registro continuo de temperatura a 15 m de profundidad en la zona oriental y occidental de la isla, y se realizo un monitoreo del patron local de circulacion superficial utili-zando un perfilador de corrientes (AWAK-ADCP) durante junio 2006 y febrero 2007. Se identificaron dos periodos contrastantes para las condiciones oceanograficas en la capa superficial (0-50 m) de la columna de agua: un periodo calido y de baja salinidad superficial entre mayo y diciembre (profundidad termoclina 47 m) y un periodo frio y salino entre enero y abril (profundidad termoclina 7,5 m). Se descarto la presencia de proceso local de surgencia y los resultados indicaron una fuerte influencia de procesos de mesoescala (surgencia en el Panama Bight) sobre la variabilidad temporal de las condiciones oceanograficas en la zona de estudio. En este mismo sentido se sugiere que la variabilidad espacial estaria mas asociada a procesos climaticos regionales (patron de precipitacion) y la cercania de la zona de estudio al complejo deltaico rio Patia - rio Sanquianga. Palabras clave: temperatura, salinidad, oceanografia, isla Gorgona, Colombia, Pacifico Oriental Tropical.

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.

The Balance of Nature and Human Impact: Anthropogenic footprints on biodiversity

One of the most concerning issues to modern ecology and society is the ongoing loss of biodiversity. Ecosystems are now losing species at rates only seen in previous mass extinction events (Hails, 2008; Barnosky et al., 2011) with rates of extinction between 100 and 1000 times higher than pre-human levels (Pimm et al., 1995). This loss, in turn, is impairing the functioning of ecosystems (Worm et al., 2006; Mora et al., 2011a) and their capacity to deliver goods and services to mankind (Díaz et al., 2006). The sharp contrast between the declining “supply” of the Earth’s services and the rising “demand” from a growing human population indicates that such services will increasingly fall short, leading to the exacerbation of hunger, poverty, and human suffering (Campbell et al., 2007; Mora & Sale, 2011). There is relatively good consensus that biodiversity loss is being driven directly or indirectly by human stressors such as overexploitation, habitat loss, invasive species, and climate change (Myers, 1995; Sala et al., 2000; Novacek & Cleland, 2001; Gaston et al., 2003; Jackson, 2008; Weidenhamer & Callaway, 2010). The relative role of such stressors, however, has been a focus of controversy as all threats do provide rational mechanisms to explain biodiversity loss and unfortunately most threats co-occur in natural conditions, making it difficult to isolate their individual effects (Myers, 1995; Sala et al., 2000; Novacek & Cleland, 2001; Mora et al., 2007). Since the cost of mitigating specific stressors could be considerable but disproportionate among different sectors of the economy (e.g., industries vs. fishers, fishermen vs. tourism developers, etc.), this uncertainty over the relative effect of anthropogenic stressors is often used as an argument to prevent the implementation of mitigation policies (e.g., Schiermeier, 2004; Worm &Myers, 2004; Grigg & Dollar, 2005). A counter-argument, however, is that any stressor at play, if proven to have a considerable effect on biodiversity, should be mitigated regardless of its effect relative to other stressors. This would, of course, require demonstrating the significance of the stressor(s) at play. In this review, we provide an overview of the current biodiversity crisis and the role of anthropogenic stressors. The evidence is considerable and although some uncertainties remain and will probably never be answered, there is considerable knowledge to suggest that a lack of policy action

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.

Age and Growth of the Round Stingray Urotrygon rogersi, a Particularly Fast-Growing and Short-Lived Elasmobranch

We examined the age and growth of Urotrygon rogersi on the Colombian coast of the Eastern Tropical Pacific Ocean by directly estimating age using vertebral centra. We verified annual deposition of growth increments with marginal increment analysis. Eight growth curves were fitted to four data sets defined on the basis of the reproductive cycle (unadjusted or adjusted for age at first band) and size variables (disc width or total length). Model performance was evaluated using Akaikes Information Criterion (AIC), AIC weights and multi-model inference criteria. A two-phase growth function with adjusted age provided the best description of growth for females (based on five parameters, DW∞  =  20.1 cm, k  =  0.22 yr–1) and males (based on four and five parameters, DW∞  =  15.5 cm, k  =  0.65 yr–1). Median maturity of female and male U. rogersi is reached very fast (mean ± SE  =  1.0 ± 0.1 year). This is the first age and growth study for a species of the genus Urotrygon and results indicate that U. rogersi attains a smaller maximum size and has a shorter lifespan and lower median age at maturity than species of closely related genera. These life history traits are in contrast with those typically reported for other elasmobranchs.

Ichthyoplankton in the Nacional Natural Park Isla Gorgona (Pacific Ocean of Colombia) during September 2005

The taxonomy, spatial distribution, and abundance patterns of ichthyoplankton collected in September 2005 from the coastal zone of Gorgona Island National Natural Park in the Colombian Pacific Ocean were analyzed. The ichthyoplankton in the study area was collected with oblique tows using a minibongo net (30 cm; 250 μm mesh). The tows were made from variable depths depending on the stations but never exceeding 50 m. A sampling grid with 24 stations was used. Fish larvae abundance was between 69 and 16,837 larvae·1000 m -3 . Larval stages of 35 species belonging to 14 families were identified. Gobiidae (35%) and Sciaenidae (15%) were the most abundant and frequent families. Lythrypnus sp. (8,519 larvae·1000 m -3 ) and Sciaenidae spp. (6,553 larvae·1000 m -3 ) were the most abundant and frequent species. The analysis of larval spatial distribution suggested a tendency to aggregate towards the south of the study zone, approximately 5 km offshore. Significant differences were detected in the ichthyoplankton abundances between the eastern and the western zones of the study area (Mann-Whitney, p = 0.000062). However, no significant relationship was observed between ichthyoplankton abundance and average temperature (Spearman, R = -0.346), salinity (Spearman, R = 0.227), and water transparency (Spearman, R = 0.10).

Reproductive patterns of the coral Pocillopora damicornis at Gorgona Island, Colombian Pacific Ocean

Abstract Knowing the gametic development of the coral Pocillopora damicornis and its relationship to environmental variation at La Azufrada reef (2°58′10″N and 78°11′05″W, Gorgona Island, Colombian Pacific Ocean) is essential to understanding the capacity for sexual replenishment of this population. Due to the lack of information about its sexual reproductive process, we collected tissue samples of healthy and unhealthy colonies (with bleaching, or algal or cyanobacterial overgrowth), along with salinity and sea-surface temperature data, between October 2010 and October 2011. During histological analysis we observed four oocyte and three spermary developmental stages in healthy colonies. Colonies were hermaphrodites with synchronous gonadal maturation in May 2011. However, polyps within colonies were either gonochoric, with a 7.8 ± 11.8:1 (mean ± SD) female to male polyp sex ratio, or hermaphroditic, with a 2.8 ± 1.5:1 (mean ± SD) oocyte to spermary ratio. The low number of spermaries observed may reduce the chance of effective fertilization and could explain the low sexual recruitment observed in the study area. There was a positive correlation between salinity and the mean number of gametes (oocytes and spermaries) produced per polyp, although both oocytes and spermaries increased during the warm water, high-salinity season (March to July 2011). Colonies with bleaching or overgrowth by cyanobacteria or algae had no gametes, suggesting that population recovery after disturbances might not be effective if it depends solely on sexual reproduction.