106 research outputs found
Control mechanisms of primary productivity revealed by Calcareous Nannoplankton from marine isotope stages 12 to 9 at the Shackleton Site (IODP Site U1385)
Nowadays, primary productivity variations at the SW Iberian Margin (IbM) are primarily controlled by wind-driven upwelling. Thus, major changes in atmospheric circulation and wind regimes between the Marine Isotope Stages (MIS) 12 and 9 could have driven substantial changes in phytoplankton productivity which remains poorly understood. We present a high-resolution calcareous nannofossil record from the Shackleton Site Integrated Ocean Discovery Program Site U1385 that allow the assessment of primary productivity and changing surface conditions on orbital and suborbital timescales over the SW IbM. These records are directly compared and integrated with terrestrial – Mediterranean forest pollen – and marine – benthic and planktic oxygen stable isotopes (δ18O), alkenone concentration [C37], Uk´37-Sea Surface Temperature and % C37:4 – proxy records from Site U1385. Our results indicate intra-interglacial increase in primary productivity together with intensification of the Azores anticyclonic high-pressure cell beyond the summer that suggests a two-phase upwelling behavior during the full interglacial MIS 11c (420–397ka), potentially drived by atmospheric NAO-like variability. Primary productivity is largely enhanced during the inception of glacial MIS 10 and the early MIS 10 (392–356ka), linked to intensified upwelling and associated processes during a period of strengthened atmospheric circulation. In agreement with the conditions observed during Heinrich events of the last glacial cycle, primary productivity reductions during abrupt cold episodes, including the Heinrich-type (Ht) events 4 to 1 (436, 392, 384 and 339ka) and the Terminations V and IV, seems to be the result of halocline formation induced by meltwater arrival, reducing the regional upward nutrient transferenceFPU17/03349, PTDC/CTA-GEO/29897/2017, UIDB/04326/2020, UIDB/04326/2020, CEECIND/02208/2017info:eu-repo/semantics/publishedVersio
Review of the effects of protection in marine protected areas: current knowledge and gaps
The effectiveness of marine protected areas (MPAs) and the conservation of marine environments must be based on reliable information on the quality of the marine environment that can be obtained in a reasonable timeframe. We reviewed studies that evaluated all aspects related to the effectiveness of MPAs in order to describe how the studies were conducted and to detect fields in which research is lacking. Existing parameters used to evaluate the effectiveness of MPAs are summarised. Two-hundred and twenty-two publications were reviewed. We identified the most commonly used study subjects and methodological approaches. Most of the studies concentrated on biological parameters. Peer reviewed studies were based on control vs. impact design. BACI and mBACI designs were used in very few studies. Through this review, we have identified gaps in the objectives assigned to MPAs and the way in which they have been evaluated. We suggest some guidelines aimedat improving the assessment of the effects of protection in MPAs
Monitoring the complex benthic habitat on semi-dark underwater marine caves using photogrammetry-based 3D reconstructions
Marine caves are dark environments considered a priority habitat for conservation included
in the EU Habitats Directive (H8330). They harbor fragile benthic communities and
represent a major reservoir of marine biodiversity. However, there is a lack of knowledge of
these habitats due to the difficulties of creating detailed benthic maps and characterizing
the biodiversity, structure, and dynamics of their communities. The uniqueness of marine
caves fosters their popularity among recreational divers, who can cause disturbances
through abrasion of the biota, resuspension of sediment, and accumulation of exhaled air
bubbles in the caves' ceilings. This study aims to build a monitoring framework to
characterize the structure and temporal dynamics of this complex habitat using Structurefrom-
Motion (SfM) photogrammetry. SfM is a novel, non-invasive technique that allows a
major advancement in the monitoring of changes in the cave’s community assemblages. This
method relies on images acquired by 4K video footage to build fine-scaled 3D digital models
of the substrate using overlapping imagery. For this study, we combined SfM
photogrammetry and photo quadrats extracted from the video recordings. We evaluate the
effectiveness of this methodology in a marine cave highly frequented by divers, located in
Illa de l’Aire (Balearic Islands, Spain), and carried out two surveys before and after the
diving season (2019-2021). As a result, we found a loss of 25 colonies of bryozoans with
fragile skeletons, like Schizoretepora sp., and 8 individual sponges with globose
morphotypes. Our results indicate that this methodology enables accurate and efficient
monitoring of benthic communities in underwater caves that allow us to better understand
their dynamics and, therefore, to develop the need management measures
Review of the effects of protection in marine protected areas: current knowledge and gaps
The effectiveness
of marine protected areas (MPAs) and the conservation of marine environments must be based on reliable
information on the quality of the marine environment that can be obtained in a reasonable timeframe. We
reviewed studies that evaluated all aspects related to the effectiveness of MPAs in order to describe how the
studies were conducted and to detect fields in which research is lacking. Existing parameters used to evaluate
the effectiveness of MPAs are summarised. Two–hundred and twenty–two publications were reviewed.
We identified the most commonly used study subjects and methodological approaches. Most of the studies
concentrated on biological parameters. Peer reviewed studies were based on control vs. impact design. BACI
and mBACI designs were used in very few studies. Through this review, we have identified gaps in the objectives
assigned to MPAs and the way in which they have been evaluated. We suggest some guidelines aimed
at improving the assessment of the effects of protection in MPAsRevisión de los efectos de la protección en las áreas marinas protegidas: conocimiento y deficiencias actuales.—
La efectividad de las áreas marinas protegidas (AMPs) y la conservación del medio ambiente marino debe
basarse en información fiable sobre la calidad del medio marino que pueda obtenerse en un plazo de tiempo
razonable. Se revisaron estudios que evalúan aspectos relacionados con la efectividad de las AMPs con el
fin de describir cómo se realizaron los estudios y detectar donde existen vacíos en la investigación. En este
estudio se enumeran los parámetros existentes para evaluar la efectividad de las AMPs. Se revisaron 224 publicaciones.
Identificamos los objetos de estudio más utilizados y los enfoques metodológicos. La mayoría de
los estudios se centran en el estudio de parámetros biológicos. Los estudios publicados se basaron en el
diseño control frente a impacto. En muy pocos estudios se utilizaron diseños de muestreo BACI y mBACI. A
través de esta revisión, se han identificado deficiencias en los objetivos de las AMPs y en la manera como
han sido evaluados. Como conclusión sugerimos algunas pautas para mejorar la evaluación de los efectos
de la protección en estas zonasPublicado
Presumed Symbolic Use of Diurnal Raptors by Neanderthals
In Africa and western Eurasia, occurrences of burials and utilized ocher fragments during the late Middle and early Late Pleistocene are often considered evidence for the emergence of symbolically-mediated behavior. Perhaps less controversial for the study of human cognitive evolution are finds of marine shell beads and complex designs on organic and mineral artifacts in early modern human (EMH) assemblages conservatively dated to ≈100–60 kilo-years (ka) ago. Here we show that, in France, Neanderthals used skeletal parts of large diurnal raptors presumably for symbolic purposes at Combe-Grenal in a layer dated to marine isotope stage (MIS) 5b (≈90 ka) and at Les Fieux in stratigraphic units dated to the early/middle phase of MIS 3 (60–40 ka). The presence of similar objects in other Middle Paleolithic contexts in France and Italy suggest that raptors were used as means of symbolic expression by Neanderthals in these regions
The ACER pollen and charcoal database: a global resource to document vegetation and fire response to abrupt climate changes during the last glacial period
Quaternary records provide an opportunity to examine the nature of the vegetation and fire responses to rapid past climate changes comparable in velocity and magnitude to those expected in the 21st-century. The best documented examples of rapid climate change in the past are the warming events associated with the Dansgaard–Oeschger (D–O) cycles during the last glacial period, which were sufficiently large to have had a potential feedback through changes in albedo and greenhouse gas emissions on climate. Previous reconstructions of vegetation and fire changes during the D–O cycles used independently constructed age models, making it difficult to compare the changes between different sites and regions. Here, we present the ACER (Abrupt Climate Changes and Environmental Responses) global database, which includes 93 pollen records from the last glacial period (73–15 ka) with a temporal resolution better than 1000 years, 32 of which also provide charcoal records. A harmonized and consistent chronology based on radiometric dating (14C, 234U∕230Th, optically stimulated luminescence (OSL), 40Ar∕39Ar-dated tephra layers) has been constructed for 86 of these records, although in some cases additional information was derived using common control points based on event stratigraphy. The ACER database compiles metadata including geospatial and dating information, pollen and charcoal counts, and pollen percentages of the characteristic biomes and is archived in Microsoft AccessTM at https://doi.org/10.1594/PANGAEA.870867
Effects of external nutrient sources and extreme weather events on the nutrient budget of a Southern European coastal lagoon
The seasonal and annual nitrogen (N), phosphorus (P), and carbon (C) budgets of the mesotidal Ria Formosa lagoon, southern Portugal, were estimated to reveal the main inputs and outputs, the seasonal patterns, and how they may influence the ecological functioning of the system. The effects of extreme weather events such as long-lasting strong winds causing upwelling and strong rainfall were assessed. External nutrient inputs were quantified; ocean exchange was assessed in 24-h sampling campaigns, and final calculations were made using a hydrodynamic model of the lagoon. Rain and stream inputs were the main freshwater sources to the lagoon. However, wastewater treatment plant and groundwater discharges dominated nutrient input, together accounting for 98, 96, and 88 % of total C, N, and P input, respectively. Organic matter and nutrients were continuously exported to the ocean. This pattern was reversed following extreme events, such as strong winds in early summer that caused upwelling and after a period of heavy rainfall in late autumn. A principal component analysis (PCA) revealed that ammonium and organic N and C exchange were positively associated with temperature as opposed to pH and nitrate. These variables reflected mostly the benthic lagoon metabolism, whereas particulate P exchange was correlated to Chl a, indicating that this was more related to phytoplankton dynamics. The increase of stochastic events, as expected in climate change scenarios, may have strong effects on the ecological functioning of coastal lagoons, altering the C and nutrient budgets.Portuguese Science and Technology Foundation (FCT) [POCI/MAR/58427/2004, PPCDT/MAR/58427/2004]; Portuguese Science and Technology Foundation (FCT
MAPPING COMMUNITY INTEREST HABITATS IN THE COLUMBRETES ARCHIPELAGO, AN EXTRAORDINARY HOT SPOT OF BIODIVERSITY
The Columbretes Archipelago and their submerged surroundings are part of an unusual,
Pleistocene volcanic field located in the Western Mediterranean designated as a Site of
Community Importance (SCI) of the Natura 2000 Network. In the present study, 4 benthic
habitats of community interest (1110, 1170, 1180 and 8330) have been identified by analyzing
several sources of information. Generalized additive models (GAMs) have been used to model
the potential distribution of reefs (1170) and maërl beds (1110). Our results highlight the
diversity and extent of these habitats and allow comparisons to other marine SCIs of Spain. This
can be attributed to the variability of the environment of this site. The Columbretes Islands
combine a relatively shallow environment with volcanic structures, hydrothermalism with active
degassing, current-driven sedimentary lobes and the influence of inland flows. Understanding
high biodiversity spots is crucial as they offer natural laboratories to describe how ecosystems
respond to the effects of global change. The knowledge obtained will be of paramount
importance for the conservation of species and habitats. Furthermore, it will establish a
baseline for future monitoring and assist in the development of effective management plans
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