Juan Manuel Ruiz Fernandez

Juan Manuel Ruiz Fernandez
Instituto Español de Oceanografia | IEO · Centro Oceanográfico de Murcia

PhD

About

46
Publications
17,177
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1,837
Citations
Additional affiliations
March 2004 - present
Instituto Español de Oceanografia
Position
  • Senior Researcher
Description
  • Seagrass ecology: basic and applied research. Topics are: - ecophysiology/stress responses - seagrass mapping - environmental impacts and ecological status assessment

Publications

Publications (46)
Article
• The critically endangered fan mussel Pinna nobilis, endemic to the Mediterranean Sea, faces a drastic population decline all over the Mediterranean Sea owing to an infectious disease. • Coastal lagoons represent one of this species’ last reservoirs; thus, knowledge of the population conservation status in these ecosystems is essential. • An exten...
Article
The potential negative influence of the seaweed Caulerpa prolifera on the seagrass Cymodocea nodosa was explored in a Mediterranean coastal lagoon (Mar Menor, Spain) where the alga suddenly and rapidly spread four decades ago. An extensive field sampling was carried out across the lagoon to characterise the distribution and abundance of both macrop...
Chapter
Full-text available
El presente artículo sintetiza la situación de la laguna costera del Mar Menor en relación con los nutrientes, centrándose especialmente en el periodo anterior a la DANA de septiembre de 2019 y en la evolución de dicha situación tras la DANA, con particular atención al episodio de mortandad masiva ocurrido a mediados de octubre de 2019. Se presenta...
Technical Report
Full-text available
A severe degradation of Mar Menor has been caused by the eutrophication process due to the excess of nutrients, degradation that the lagoon has been suffering since the 2016 eutrophic event and that has been aggravated by the nutrient and sediments contained in the runoff caused by the subtropical jet stream of September 2019
Article
The invasive seaweed Caulerpa cylindracea has shown a reduced ability to invade healthy Posidonia oceanica meadows by penetrating only meadow margins in early invasion stages in the western Mediterranean Sea. However, the long-term interaction with invasive seaweed could deteriorate the structure of meadows by diminishing their initial resistance t...
Conference Paper
In shallow coastal ecosystems, as for example coastal lagoons, macrophytes account for high biomasses and productivity (Sand-Jensen 1975, Viaroli et al. 1996) being able to play a major role in the biogeochemical cycles of nutrients (Romero et al. 2006, Touchette and Burkholder 2000). When strong inputs of nutrients occur, due to natural and/or ant...
Presentation
The effects of global warming are a matter of concern and are increasing study. All organisms are affected, especially habitat forming species among them marine plants. Besides temperature is among the most widely studied environmental factors, the predictions usually do not take into account that temperature increase rarely acts isolated from othe...
Article
Abstract Increased plant mortality in temperate seagrass populations has been recently observed after summer heatwaves, although the underlying causes of plant death are yet unknown. The potential energetic constrains resulting from anomalous thermal events could be the reason that triggered seagrass mortality, as demonstrated for benthic invertebr...
Article
Full-text available
Global warming is emerging as one of the most critical threats to terrestrial and marine species worldwide. This study assessed the effects of simulated warming events in culture on two seagrass species, Posidonia oceanica and Cymodocea nodosa, which play a key role in coastal ecosystems of the Mediterranean Sea. Changes in fatty acids as key metab...
Article
The Mediterranean endemic seagrass Posidonia oceanica is generally regarded as a stenohaline species, highly sensitive to salinity increments; however, in a few particular cases, natural populations can grow under salinity levels above its normal threshold of tolerance. One such case is a population of P. oceanica in the southeastern coastal region...
Technical Report
Full-text available
Caracterización y valoración ecológica de las praderas de Cymodocea nodosa del Mar Menor en relación a las presiones antrópicas existentes. La valoración del estado de las praderas se realiza base a un conjunto de descriptores, estructurales y funcionales, que abarcan desde el nivel bioquímico/fisiológico hasta el nivel poblacional/comunidad. Tamb...
Article
Posidonia oceanica seagrass meadows are one of most resistant Mediterranean habitats to invasion by the green alga Caulerpa cylindracea. We evaluated the hypothesis that light reduction caused by the seagrass canopy can limit algal photosynthesis and growth and hence potentially explain this resistance. To this end, we analysed light regimes and C....
Conference Paper
Full-text available
The Mar Menor (135 km2) is one of the most important hypersaline coastal lagoons in the Western Mediterranean Sea, its bottoms were originally colonized by monospecific meadows of the seagrass C. nodosa. However, since the 1970’s, drastic hydrographic changes caused by various human activities has seen the expansion of a number of species common in...
Article
Reduction in light availability caused by the canopy of the Mediterranean seagrass Posidonia oceanica has been suggested as a critical mechanism to resist the invasion of the exotic macroalga Caulerpa cylindracea. We experimentally evaluated the role of light as a limiting factor on the capacity of colonization and spread of this invasive seaweed i...
Article
Full-text available
Changes in plant water relations and ionic homoeostasis can determine plant osmoacclimation and tolerance to hypersaline stress. In this study, we examined the role of ion accumulation in short-term osmotic acclimation capacities of two Mediterranean seagrass species (Posidonia oceanica and Cymodocea nodosa) with differentiated ranges of salinity t...
Article
Brine discharged directly into the sea from desalination processes, forms a very dense plume that spreads out over the sea floor following the steepest slope due to its greater density than ambient sea water. Because the large difference in density slows down brine dilution processes in ambient sea water, hypersaline plumes spread out over broad ar...
Article
In the present study, we investigated the capacity for non-radiative energy dissipation operated by thexanthophyll cycle pigments of the Mediterranean seagrasses Posidonia oceanica and Cymodocea nodosa,under normal and increased salinity conditions. After being chronically stressed by hypersalinity duringseveral months in a mesocosm system, the eff...
Article
There are major concerns in the Mediterranean Sea over the effects of hypersaline effluents from seawater desalination plants on seagrass communities. However, knowledge concerning the specific physiological capacities of seagrasses to tolerate or resist salinity increases is still limited. In this study, changes in the photosynthetic characteristi...
Article
The present study examines for the first time the effects of increased salinity on water relations and osmolyte (carbohydrates and amino acids) concentrations in two Mediterranean seagrass species, Posidonia oceanica and Cymodocea nodosa, which are adapted to growth in environments with contrasting salinity and have a known differential sensitivity...
Article
This work concerns the monitoring of a Mediterranean maërl bed influenced by an experimental fish cage culture for eighteen months. The maërl bed showed an a priori stratified distribution with depth, which led to the selection of a stratified random sampling design that also took into account the gradient of influence by the fish cages. Maërl cove...
Article
Full-text available
The photosynthetic plasticity of the invasive green alga Caulerpa racemosa v. cylindracea (hereafter C. racemosa) has been proposed as a relevant mechanism determining its successful performance on Mediterranean benthic assemblages over broad depth gradients. In the present study, the photosynthetic performance of C. racemosa was evaluated through...
Article
Full-text available
Spread of the invasive alga Caulerpa racemosa var. cylindracea (Caulerpales, Chlorophyta) along the Mediterranean Coast of the Murcia region (SE Spain).— The aim of this paper was to document the appearance and spread of the green alga Caulerpa racemosa along the coast of Murcia in south–eastern Spain. It was found for the first time in the area in...
Article
In this study we develop and evaluate a macroalgal bioassay tool for monitoring the spatial extent of dissolved wastes loaded from offshore fish farms into the marine coastal ecosystem. This tool is based on the analysis of the nitrogen stable isotope ratio (delta(15)N) in tissues of several benthic primary producers (macroalgae and Posidonia ocean...
Article
Full-text available
A 6-month macrograzer exclusion field experiment was conducted in an altered Posidonia oceanica meadow affected by organic effluents from a fish farm. This experiment was carried out in order to ascertain whether or not overgrazing had contributed to the meadow degradation observed, because higher densities of macrograzers (mainly the sea urchin Pa...
Article
Full-text available
Special Issue Mediterranean Seagrasses. Guest Introduction
Article
The aim of this study was estimating the remote influence of waste dispersed from a large off-shore fish farm complex (6197 ton year(-1)) on the near-shore Posidonia oceanica meadow (26-27 m deep) located at a distance of 3 km. Measurements of isotopic nitrogen content in epiphytes and seagrass leaf tissues, epiphyte biomass, shoot size, herbivory...
Article
Full-text available
The dominant Mediterranean seagrass Posidonia ocea-nica inhabits sublittoral environments with very stable salinity regimes; the species is considered highly sensi-tive to even moderate increases in salinity caused by hypersaline effluents (brine) from desalination plants. We analysed the effect of salinity increase on seagrass vitality and surviva...
Article
The development of aquaculture along the Mediterranean coastline degrades the marine environment, in particular Posidonia oceanica meadows, which, in extreme cases, show high mortality. Here we studied the effects of organic matter and nutrient input from the effluents of three fish farms, located along the Mediterranean coast, on P. oceanica physi...
Article
The effect of increased sediment sulfide concentrations on the sulfur isotopic composition (δ34S), total sulfur (TS) and elemental sulfur (S0) concentrations in plant tissues was studied for the two seagrasses Zostera marina (3 weeks in laboratory) and Posidonia oceanica (4 months in situ). Porewater sulfide concentrations were experimentally regul...
Article
Here we studied the effects of adding organic carbon and nutrients to sediment on the physiology and survival of the seagrass Posidonia oceanica in a field experiment in the Medes Islands (NE Spain). Nine randomly selected plots were established at a depth of 10 m; three were enriched with organic carbon (OM treatment), three with organic carbon an...
Article
The intensive reconstructive sampling (1957–2004, 39 localities), a systematic direct observation (1992–2004, 1 locality) and particular direct observations (66 localities) of Posidonia oceanica meadows were analysed together with temporal series of flowering available in the literature (19 localities). This allowed the examination of temporal and...
Article
The light-limitation hypothesis was tested to assess whether water turbidity had caused the decline of a Mediterranean Posidonia oceanica (L.) Delile meadow in an area affected by a harbor. The annual growth, photosynthesis and rhizome starch concentrations of seagrass were measured and related to changes in light availability and dissolved nutrien...
Article
The spatial extent and timing of the impact of fish farms on the distribution and performance of a Posidonia oceanica meadow were examined in an embayment of the south-eastern coast of Spain (Hornillo Bay, Murcia). Changes in seagrass distribution were determined using available seagrass mapping (from 1988, i.e., before the onset of aquaculture act...
Article
Full-text available
The response of the Mediterranean seagrass Posidonia oceanica (L.) Delile to in situ Light reduction was examined over a 4 mo period (May to August) in 1993 and 1995. Shoot density, leaf growth rate, shoot size, photosynthetic activity, carbohydrate reserves, epiphyte load and tissue nutrient concentrations were measured in replicated plots under t...
Article
The influence of eutrophication associated with the presence of coastal constructions (dykes, quays and seaports) and several natural phenomena over the benthic biological communities in a bay of southeastern Iberia (Aguilas, Murcia) is studied in this work. This bay has an area of 6.3 km2, where a small floodway, belonging to a drainage system of...

Projects

Projects (3)
Project
Although Phyllospadix sps (P. torreyi, P, scouleri) conform the most productive seagrass beds along the Pacific coast from Alaska to Baja California, the knowledge about their biology and ecology is still scarce. Our main objective is to elucidate how these seagrass species could respond in a future scenario of climate change, focusing on thermal stress (heat waves, fluctuating temperature) and its interaction with other environmental factors, such as light or nutrient availability. We will also propose Phyllospadix sps as key Biological Quality Indicators of environmental impact, and we 'will establish the first monitoring network for these species along the coastline of Baja. This ambitious project will be developed with a strong multidisciplinary approach, including researchers with expertise in physical oceanography, marine biochemistry, marine macrophytes ecophysiology and plant molecular ecology.
Project
The HEATGRASS project aims to find out how the increase in the frequency and intensity of heat waves will affect the valuable P. oceanica meadows, and to assess how they will respond under the effects of climate change. The project is based on mesocosm experimentation and will combine transcriptomic and ecophysiological approaches. In this frame, the use of plants from extremes of main spatial thermal gradients of the species (i.e. bathymetric and latitudinal gradients) will be greatly useful to reveal the physiological and genetic basis of thermal adaptation and tolerance in terms of divergent responses, and to forecast future climate change scenarios. These will be integrated in order to formulate and prioritize conservation and management strategies. The project adopts an interdisciplinary and multidisciplinary approach by using ecophysiological, genetic and transcriptomic techniques and encompassing the fields of ecophysiology, molecular ecology, population genetics and bioinformatics, integrating findings within the context of seagrass ecology and conservation.