José Carlos Hernández

Universidad de La Laguna | ULL · Biología Animal, Edafología y Geología

Large populations of the sea urchin Diadema aff. antillarum occur in the east Atlantic archipelagos. The origin and stability of these large herbivorous populations are not well known. Variability in settlement, recruitment and adult urchin density were quantified and compared over a 7 yr period (2002 to 2008) within the Canary Islands. Variables t...

A pronounced, widespread and persistent regime shift among marine ecosystems is observable on temperate rocky reefs as a result of sea urchin overgrazing. Here, we empirically define regime-shift dynamics for this grazing system which transitions between productive macroalgal beds and impoverished urchin barrens. Catastrophic in nature, urchin over...

Recurrent sea urchin mass mortality has recently affected eastern Atlantic populations of the barren-forming sea urchin Diadema africanum. This new episode of die-off affords the opportunity to determine common meteorological and oceanographic conditions that may promote disease outbreaks. The population dynamics of this sea urchin species are well...

Relationships between sea urchins and non-crustose macroalgae are typically non-linear, and an abrupt phase shift from a barren to a macroalgae-dominated state and vice versa happens when the sea urchin abundance exceeds a critical threshold. Here we have used two mass mortality events as a natural experiment to study progressive changes and dynami...

Diadema aff. antillarum performs a key role in organizing and structuring rocky macroalgae assemblages in the Canary Islands. Densities of D. aff. antillarum higher than 2 individuals m(-2) are found to drastically reduce non-crustose macroalgal cover to below 30% and wave exposure appears as a major factor determining sea urchin density, which dec...

Full-text view-only version of this paper: https://rdcu.be/c3phg. The green phyllodocids Eulalia clavigera and E. viridis are a known European pseudo-cryptic complex, but questions about its distribution and evidence of additional lineages in previous studies call for an investigation of the real diversity within the complex. We analyze DNA sequenc...

Morphologically similar species are often overlooked but molecular techniques have been effective in signalling potential hidden diversity, boosting the documentation of unique evolutionary lineages and ecological diversity. Platynereis dumerilii and Platynereis massiliensis are part of a recognised species complex, where differences in the reprodu...

This paper examines various fishery management scenarios based on the recovery of small-scale fisheries (SSF) following a submarine volcanic eruption in 2011 in El Hierro Island (Canary Islands, Spain). After this catastrophic event, the SSF composition of La Restinga fishing community was affected by socio-economic and demographic changes. The unc...

Early developmental stages of echinoids have been thoroughly studied but continue to offer remarkable insights for the current understanding of biological sciences. The sea urchin Sphaerechinus granularis has been commonly tested by exposing its developmental stages to a variety of stressors, but current descriptions about developmental time and mo...

In recent years, recurrent sea urchin mass mortalities in the Canary Islands have been registered. These mortality-related events have decimated 93% of the eastern Atlantic populations of the barren-forming sea urchin Diadema africanum. Two severe episodes of rough southeastern seas led to winter storms in February 2010 (Xynthia) and February 2018...

We have used the common black sea urchin A. lixula, as a model species to study genomic diversity, divergence, and signs of local adaption across a natural pH gradient existing along short geographical distances.

Global warming and ultraviolet radiation (UVR) affect marine organisms worldwide. However, we still lack knowledge about the consequences of these environmental changes to range-restricted macroalgae species, such as Gelidium canariense , a habitat-forming endemic of the Canary Islands. The aim of this study is to provide useful data for analyzing...

Understanding and forecasting the effects of climate changes on vulnerable species are leading concerns for ecologists and conservation biologists. Herbaria are invaluable for use in long-term data series, and one of the few available methods for quantifying biodiversity changes over large periods of time. Gelidium canariense is an endemic and habi...

We present a new natural carbon dioxide (CO2) system located off the southern coast of the island of La Palma (Canary Islands, Spain). Like CO2 seeps, these CO2 submarine groundwater discharges (SGDs) can be used as an analogue to study the effects of ocean acidification (OA) on the marine realm. With this aim, we present the chemical characterizat...

Recent studies reporting complexes of cryptic or pseudo-cryptic species with narrow geographic distributions have been challenging the cosmopolitan status of a fair number of marine benthic invertebrates. Morphologically similar species are often overlooked but molecular techniques have been extremely effective in signalling potential hidden divers...

Estudio observacional sobre la llegada y el estado actual de las poblaciones del cangrejo decápodo pantropical Cronius ruber (Lamarck, 1818) en la isla de Tenerife. Se trata de una especie de la familia Portunidae, cuyos primeros registros publicados en Canarias se producen en el año 2017, siendo citada por primera vez en el litoral de Tenerife en...

Dos eventos de mortalidad masiva en 2009-2010 y 2018 han diezmado las poblaciones del erizo de mar Diadema africanum en los archipiélagos de Ca- narias y Madeira (Atlántico subtropical oriental). En estas islas, este erizo es un herbívoro clave que controla el crecimiento de las macroalgas en los ecosistemas rocosos. Como resultado de la sobrepesca...

We present a new natural carbon dioxide (CO2) system located off the southern coast of La Palma Island (Canary Islands, Spain). Like others CO2 seeps, these seeps can be used as an analogue to study the effects of ocean acidification (OA) on the marine realm. With this aim, we present an accurate chemical characterization of the seeps system carbon...

Diadema africanum is a recently described sea urchin from the Eastern Atlantic archipelagos, and adults play a major ecological role mediating the transition between two alternative ecosystem states: macroalgal beds and urchin barrens. The aim of this study was to describe for the first time the egg characteristics, fertilization and larval develop...

Modeling is a useful approach to learn about the capacity of the systems to recover after disturbances. In October 2011, a submarine volcanic eruption in The Punta Restinga-Mar de Las Calmas Marine Protected Area (RMC-MPA) caused catastrophic mass mortality. We modeled the recovery dynamics of the fully protected (no-take zone), partially protected...

Estimating survival rate is a basic part of population studies. Generally it is assumed that populations being studied are both stable and stationary. This probably is seldom the case although as a long-term average populations may persist at a mean density. Estimating survival in short-term studies may fail to capture average rates. A long-term st...

Human activity is generating an excess of atmospheric CO2, creating what we know as ocean acidification, which it is predicted to causes important changes in marine ecosystems. Until recently, most of the research on this phenomenon has been carried out under laboratory conditions, with small-scales, using few representative species and live cycle...

Human activity is generating an excess of atmospheric CO2, resulting in what we know as ocean acidification, which produces changes in marine ecosystems. Until recently, most of the research in this area had been done under small-scale, laboratory conditions, using few variables, few species and few life cycle stages. These limitations raise questi...

The recent decrease in seawater pH has stimulated a great deal of research on the effects of ocean acidificationon various organisms. Most of these studies have mainly focused on the direct effects of acidification on or-ganisms. However, the effects on ecological interactions have been poorly studied. In this paper we have focusedon determining the effe...

In the present paper a growth model for the sea urchin Arbacia lixula is proposed for the first time. A total of 1900 individuals were tagged with calcein, in four localities of Tenerife. After one year, a total of 1638 specimens were recaptured, of which 32 were tagged. Later, the increase in the demi-pyramid of Aristotle's lantern was measured un...

The Cocos Island National Park is a pristine and unique place on earth. The sea urchin Diadema mexicanum is a common inhabitant of the coral reef communities around the island. Its grazing activity is critical to control macroalgae growth, because it increases the survival of coral recruits. However, the outbreaks of sea urchin populations lead to...

The present study aims to examine the effect of the marine protected reserve of the islands of Ventotene and Santo Stefano, by studying the biomass of the fish community in the different protected zones. For that they sampled and sized the fish in two periods of time and in different locations, within the reserve. The fish species that were found w...

Arbacia lixula (Linnaeus, 1758) is a sea urchin belonging to Arbaciidae family, it is commonly known as black sea urchin. It is one of three sea urchin more abundant in the coasts of Tenerife but it is also present in great part of the Atlantic Ocean and Mediterranean sea. In this study, we aim to determine the relationship between the test size an...

Many sea urchins can detect light on their body surface and some species are reported to possess image-resolving vision. Here we measure the spatial resolution of vision in the long-spined sea urchin Diadema africanum, using two different visual responses: a taxis towards dark objects and an alarm response of spine-pointing towards looming stimuli....

One of the most important environmental factors controlling the distribution, physiology, morphology and behaviour of marine invertebrates is ocean pH. In the last decade, the effects of decreasing ocean pH as a result of climate change processes (i.e. ocean acidification) on marine organisms have been target of much research. However, the effects...

Ocean warming and acidification are the two most significant side effects of carbone dioxide emissions in the world's oceans. By changing water, temperature and pH are the main environmental factors controlling the distribution, physiology, morphology and behaviour of marine invertebrates. This study evaluated the combined effects of predicted high...

Size, growth, and density have been studied for North American Pacific coast sea urchins Strongylocentrotus purpuratus, S. droebachiensis, S. polyacanthus, Mesocentrotus (Strongylocentrotus) franciscanus, Lytechinus pictus, Centrostephanus coronatus, and Arbacia stellata by various workers at diverse sites and for varying lengths of time from 1956...

Gelidium canariense and G. arbusculum, coexist in the upper sublittoral in the Canary Islands, and are the only Gelidiales registered as vulnerable species. Spore germination and formation of rhizoids are vital steps for the successful growth of new plants. We investigated the initial germination stages of tetraspores and the growth of the primary...

Shallow subtidal macroalgal communities in the North-eastern Atlantic archipelagos (Azores, Madeira, Canaries and Cape Verde) were studied in order to identify their spatial organization patterns and the main drivers of change. Fifteen islands 20 and 145 sites across 15º of latitude and 2 850 km were sampled. We found high spatial variability acros...

Primary production and respiration rates were studied for six seaweed species (Cystoseira abies-marina, Lobophora variegata, Pterocladiella capillacea, Canistrocarpus cervicornis, Padina pavonica and Corallina caespitosa) from Subtropical North-East Atlantic, to estimate the combined effects of different pH and temperature levels. Macroalgal sample...

Echinoids play an important role in marine ecosystems structuring. Often, their population density experience markedly fluctuations that promote a state shift in the ecosystems they inhabit. Population increments of some sea urchins may cause catastrophic changes in temperate areas of the planet by decimating the erect macroalgae cover. These popul...

En el año 2016 descubrimos una zona de surgencias submarinas de CO2 en la costa de Fuencaliente, al SE de la isla de La Palma (Islas Canarias, Atlántico Oriental). Este descubrimiento ofrece una oportunidad única para abordar el estudio de los efectos, a largo plazo, de la acidificación en el océano Atlántico, mediante experimentación in situ. Adem...

Stranding’s of sea turtles in the Canary Islands occur with a high frequency. In the main islands, a digitized record of the occurrences of stranding’s has been carried out since 1998. Although this has been done independently on each island. In this work, a compilation of the digitized stranding’s data is made throughout the Canaries, from 1998 to...

In the Canaries, some coastal species of molluscs, crustaceans and annelids have been shellfish resources from prehispanic times to the present, both for their nutritive value and bait for fishing. This has led to the gradual decrease of the populations of these species, being necessary for the administration to regulate the coastal extraction and...

The ocean are important sinks of atmospheric CO2 emitted by human activities. In last decades and due to the increase concentration of this gas in the atmosphere, the chemistry of the sea water has been severely altered producing a phenomenon known as ocean acidification. This study focuses on the effects of the pH decrease, due to a natural CO2 co...

In the Canaries, some species of “burgados” (littoral gastropod molluscs) have been consumed as seafood, which are relatively abundant in its coasts. The intensive local fishing and the non-regularization of their catch has led to the loss of a large part of the population, being reduced to small groups distributed in specific points of the islands...

The huge quantities of carbon dioxide (CO2) released into the atmosphere by human activities have caused changes on ocean’s chemistry. The pH has already decreased 0,1 units and seawater acidity is expected to increase if CO2 emissions continue at the current rate. This ocean acidification process (OA) has profound implications on calcifying specie...

A study of the populations of the mollusc gastropod Micromelo undatus, which inhabits the intertidal pools of the northwest coast of Tenerife, is carried out. The interest of its study is due to the fact that it is a species of more southern latitudes and, in the last decades, has colonized the coast of the western islands of the Canaries. Global w...

Herbivory is a widespread biotic interaction with important ecological and evolutionary implications. Benthic marine systems show greater producer consumption than any other aquatic or terrestrial environment. Marine algae and plants have a variety of defensive mechanisms such as structural, chemical, and nutritional traits with the capacity to red...

Echinoids play an important role in marine ecosystems structuring. Often, their population density experience markedly fluctuations that promote a state shift in the ecosystems they inhabit. Population increments of some sea urchins may cause catastrophic changes in temperate areas of the planet by decimating the erect macroalgae cover. These popul...

This study aims to determine how it affected the underwater eruption of El Hierro, which occurred in 2012, mesoinvertebrate populations of rocky substrates. The parameters studied were the abundance and diversity of species sampled shallow and deep depths and in 14 locations with varying degrees of involvement of the volcano. The underwater eruptio...

Changes in the structure of seaweed communities were examined following a massive CO2 input. This CO2 input was caused by a submarine eruption near the coast of El Hierro island (Canary Islands, Spain). The event lasted almost five months (October 2011 - March 2012) and created a significant pH gradient. Specifically, we compared three different zo...

The present study aims to explore the structure and biomass of fish communities in different habitats of the Canary Islands, as well as todetermine the influence of nutrients and primary production (plancktonic-benthic). To conduct this study, abundance and length of fishes were collected in three periods at the four most common phytocenosis of the...

Though phenotypically plastic responses in echinoids are well studied, the majority of the literature examines the effect of altered diet. Some species, however, such as the purple sea urchin, Strongylocentrotus purpuratus, occur over a large geographic range and thus experience a variety of substrate types and wave forces. To determine whether the...

This study aims to compare the efficiency of two underwater visual census methods on tropical fish communities of Murdeira bay, off the southwestern coast of Sal Island, Cabo Verde. Two methods were tested: strip belt transect and stationary point count. Parameters compared were: species richness, abundance and diversity (d’). The results show that...

We evaluated the effectiveness of chemical tagging with the fluorescent marker calcein for two key species of herbivorous sea urchins, Diadema africanum and Paracentrotus lividus, to facilitate medium- and long-term ecological experiments. In total, 98 juveniles of D. africanum and 98 P. lividus were tagged with this fluorescent marker, with 12 com...

Oscillations of ocean pH are largely unknown in coastal environments and ocean acidification studies often do not account for natural variability yet most of what is known about marine species and populations is found out via studies conducted in near shore environments. Most experiments designed to make predictions about future climate change scen...

The rocky intertidal shore of the north coast of Tenerife is subjected to a great anthropic pressure due to fishing-shellfishing and recreational activities. In the present study, it has been analysed the effect of the geographical locality, the human activity and vertical distribution on the population of the gastropod mollusc Phorcus sauciatus (K...

We tested the suitability of three different kinds of artificial collectors designed for quantitative assessment of settlement rates of echinoids. The three kinds of collectors tested were: (1) nylon nets containing plastic biofilter balls, (2) vertical scrub brushes with vegetal bristles and (3) horizontal triangular mats of coconut fibre. We meas...

Many species have experienced recent range expansions due to human-mediated processes, such as the unintentional transport on ships or plastic waste and ocean warming, which facilitates many tropical species to tolerate living beyond their normal limit of distribution, with a potential impact on autochthonous assemblages. In September 2008, three c...

The present study is focus on the analysis of absorption and sequestration of CO2 by four benthic communities of rocky reefs in the litoral of Tenerife (Lobophora variegata, Cystoseira abies – marina, gelidiales and barren).Using a experimental design in the laboratory we determined the metabolic activity of the communities (photosynthesis and resp...

Ocean acidification is causing changes to the chemistry and biology of the marine environment, in ways that we are only just beginning to understand. Growing evidences demonstrate that ocean acidification can influence the survival, growth, development, and physiology of marine invertebrates. Here, we assessed the impact of ocean acidification on t...