Variability of the Sea Surface Temperature Around Cuba

Space and time variability of sea surface temperature in oceanic and shelf waters of Cuba were examined using the Advanced Very High Resolution Radiometer (AVHRR) sensors flown on satellites operated by the National Oceanic and Atmospheric Administration from February 1995 to August 2001. Statistics at 90 specific time series stations around Cuba were extracted from the AVHRR images to characterize shelf and oceanic waters using the long-term overall mean, minimum, and maximum sea surface temperature (SST) values. Shelf and oceanic waters reached SST maxima (29.5-30.5°C) in August. Waters off southern and western Cuba reached slightly higher temperatures than those off the northeast in the Old Bahamas Channel; waters along the northern coast of Cuba were about 1°C cooler on average than those along the southern coast. Oceanic waters around Cuba experienced minima (24.5-25.5°C) in February-March, about a month after shelf waters. Only minor regional differences in maximum temperatures were observed in shelf areas. Shelf regions around Cuba have lower annual average SSTs than adjacent oceanic waters, and the range of monthly average SST of shelf waters exceeded that of oceanic waters by 3°C, with the largest differences observed during winter. Shelf waters also cooled down at \u3e0.04°C/d, or twice as fast as oceanic waters (0.02°C/d) by action of sensible heat and evaporative losses. Shelf waters also warmed up at rates exceeding 0.06°C/d, which was two to three times faster than oceanic waters (0.02-0.03°C/d). SST anomalies were slightly positive between February 1995 and February 1999 and slightly negative from October 1999 to August 2001. In summer of 1995, 1997, and 1998, coral bleaching was observed in northern and southern reefs of Cuba. Summer anomalies \u3e1°C occurred in May 1995 and August 1997, which may have contributed to the coral bleaching

Strategic Actions to Value, Conserve, and Restore the Natural Capital of Megadiversity Countries: The Case of Mexico

Decisionmakers need updated, scientifically sound and relevant information to implement appropriate policy measures and make innovative commitments to halt biodiversity loss and improve human well-being. Here, we present a recent science-based synthesis on the biodiversity and ecosystem services of Mexico, intended to be a tool for policymakers. We describe the methodological approach used to undertake such an assessment and highlight the major findings. Organized into five volumes and originally written in Spanish (Capital Natural de México), it summarizes the available knowledge on the components, structure, and functioning of the biodiversity of Mexico; the threats and trajectories of anthropogenic impact, together with its conservation status; and the policies, institutions, and instruments available for its sustainable management. We stress the lessons learned that can be useful for similar exercises in other megadiverse developing countries and identify major gaps and strategic actions to conserve the natural capital in light of the challenges of the Anthropocene

Natural variability of surface oceanographic conditions in the offshore Gulf of Mexico

AbstractThis work characterizes patterns of temporal variability in surface waters of the central Gulf of Mexico. We examine remote-sensing based observations of sea surface temperature (SST), wind speed, sea surface height anomaly (SSHA), chlorophyll-a concentration (Chl-a) and Net Primary Production (NPP), along with model predictions of mixed layer depth (MLD), to determine seasonal changes and long-term trends in the central Gulf of Mexico between the early 1980s and 2012. Specifically, we examine variability in four quadrants of the Gulf of Mexico (water depth >1000m). All variables show strong seasonality. Chl-a and NPP show positive anomalies in response to short-term increases in wind speed and to cold temperature events. The depth of the mixed layer (MLD) directly and significantly affects primary productivity throughout the region. This relationship is sufficiently robust to enable real-time estimates of MLD based on satellite-based estimates of NPP. Over the past 15–20years, SST, wind speed, and SSHA show a statistically significant, gradual increase. However, Chl-a and NPP show no significant trends over this period. There has also been no trend in the MLD in the Gulf of Mexico interior. The positive long-term trend in wind speed and SST anomalies is consistent with the warming phase of the Atlantic Multidecadal Oscillation (AMO) that started in the mid-90s. This also coincides with a negative trend in the El Niño/Southern Oscillation Multivariate ENSO Index (MEI) related to an increase in the frequency of cooler ENSO events since 1999–2000. The results suggest that over decadal scales, increasing temperature, wind speed, and mesoscale ocean activity have offsetting effects on the MLD. The lack of a trend in MLD anomalies over the past 20years explains the lack of long-term changes in chlorophyll concentration and productivity over this period in the Gulf. Understanding the background of seasonal and long-term variability in these ocean characteristics is important to interpret changes in ocean health due to episodic natural and anthropogenic events and long term climate changes or development activities. With this analysis we provide a baseline against which such changes can be measured

Monitoring holopelagic Sargassum spp. along the Mexican Caribbean coast: understanding and addressing user requirements for satellite remote sensing

Massive influxes of holopelagic Sargassum spp. (Sargassum natans and S. fluitans) have been causing major economic, environmental and ecological problems along the Caribbean coast of Mexico. Predicting the arrival of the sargassum as an aid to addressing these problems is a priority for the government, coastal communities and the society; both mitigating the impacts and providing opportunities for its use. Lack of data concerning precise locations and times of sargassum beachings means that public and private funds are being spent inefficiently and most actions are reactive. The dynamic nature of sargassum beachings/influxes render conventional ground-based monitoring insufficient. Earth observation and cloud-based processing services offer tools to track, quantify and understand sargassum beaching remotely in a frequent, systematic and reliable manner with the temporal and spatial resolutions required for its management. In order to find the right solutions to address this problem, in this paper the needs and requirements of stakeholders are taken into consideration for the development of an Earth observation-based service to monitor sargassum along the Mexican Caribbean coast. Routine monitoring of sargassum over a large area will be cost effective and help mitigate the negative effects of sargassum influxes. The combination of imagery from Planet, specifically their SuperDove systems that provide daily data at 3 m spatial resolutions, with the freely available EU Copernicus data would be useful for many different stakeholders and potential users. A prototype of the service is presented, based on the main user requirements. The system would enable public and private organizations to allocate resources appropriately in affected areas quickly and efficiently, thereby minimizing economic, social and environmental impacts and enhancing the resilience of local communities. It would also assist the sargassum industry in the collection of fresh algae for onward processing. The system could easily be implemented for similar types of environmental monitoring in the Greater Caribbean and beyond

Caribbean Reef Drowning During Slow Mid-Holocene Sea-Level Rise

Predicting if reefs can keep pace with future sea-level (SL) rise is problematic because accretion occurs over geological timescales. For example, although meltwater pulses drowned reefs during postglacial SL rise, drowning has also been reported during the mid Holocene, when SL rise was slower and meltwater pulses unlikely. Here we report the discovery of a drowned incipient reef-crest on the widest part of northeast Yucatan shelf. Our data show the reef is an array of closely-spaced patches that crest at -14 m. These patches consist of 3 m-thick stands of Acropora palmata that grew over a Pleistocene dune ridge ~8 ka ago, but subsequently failed to keep pace with rising SL. We hypothesize that this failure is due to the suppression of coral recruitment by high sediment flux on wide shelves. Although recruitment does occur as the surf zone crosses topographic residuals during the transgression, suppression in sandy reef-fronts and back-reefs limits accretion of these incipient crests, causing their slow drowning during SL rise. We conclude that although reefs can slowly develop breakwaters in such settings, they may be incapable of vertical accretion and thus vulnerable to drowning. Identifying reefs with this vulnerability will be key to managing future SL rise

Caribbean Reef Drowning During Slow Mid-Holocene Sea-Level Rise

Predicting if reefs can keep pace with future sea-level (SL) rise is problematic because accretion occurs over geological timescales. For example, although meltwater pulses drowned reefs during postglacial SL rise, drowning has also been reported during the mid Holocene, when SL rise was slower and meltwater pulses unlikely. Here we report the discovery of a drowned incipient reef-crest on the widest part of northeast Yucatan shelf. Our data show the reef is an array of closely-spaced patches that crest at -14 m. These patches consist of 3 m-thick stands of Acropora palmata that grew over a Pleistocene dune ridge ~8 ka ago, but subsequently failed to keep pace with rising SL. We hypothesize that this failure is due to the suppression of coral recruitment by high sediment flux on wide shelves. Although recruitment does occur as the surf zone crosses topographic residuals during the transgression, suppression in sandy reef-fronts and back-reefs limits accretion of these incipient crests, causing their slow drowning during SL rise. We conclude that although reefs can slowly develop breakwaters in such settings, they may be incapable of vertical accretion and thus vulnerable to drowning. Identifying reefs with this vulnerability will be key to managing future SL rise

Using Simulated Pest Models and Biological Clustering Validation to Improve Zoning Methods in Site-Specific Pest Management

Site-specific pest management (SSPM) is a component of precision agriculture that relies on spatially enabled agronomic data to facilitate pest control practices within management zones rather than whole fields. Recent integration of high-resolution environmental data, multivariate clustering algorithms, and species distribution modeling has facilitated the development of a novel approach to SSPM that bases zone delineation on environmentally independent subfield units with individual potential to host pest populations (eSSPM). Although the potential benefits of eSSPM are clear, methods currently described for its implementation still demand further evaluation. To offer clear insight into this matter, we used field-level environmental data from a Tahiti lime orchard and realistic simulations of six citrus pests to: (1) generate a series of virtual (i.e., controlled) infestation scenarios suitable for methodological testing purposes, (2) evaluate the utility of nested (i.e., within-cluster) partitioning essays to improve the accuracy of current eSSPM methods, and (3) implement two biological clustering validators to evaluate the performance of 10 clustering algorithms and choose appropriate numbers of management zones during field partitioning essays. Our results demonstrate that: (1) nested partitioning essays outperform zoning methods previously described in eSSPM, (2) more than one clustering algorithm tend to be necessary to generate field partition models that optimize site-specific pest control practices within crop fields, and (3) biological clustering validation is an essential addition to eSSPM zoning methods. Finally, the generated evidence was integrated into an improved workflow for within-field zone delineation with pest control purposes

Retrograde Accretion of a Caribbean Fringing Reef Controlled by Hurricanes and Sea-level Rise

Predicting the impact of sea-level (SL) rise on coral reefs requires reliable models of reef accretion. Most assume that accretion results from vertical growth of coralgal framework, but recent studies show that reefs exposed to hurricanes consist of layers of coral gravel rather than in-place corals. New models are therefore needed to account for hurricane impact on reef accretion over geological timescales. To investigate this geological impact, we report the configuration and development of a 4-km-long fringing reef at Punta Maroma along the northeast Yucatan Peninsula. Satellite-derived bathymetry (SDB) shows the crest is set-back a uniform distance of 315 ±15 m from a mid-shelf slope break, and the reef-front decreases 50% in width and depth along its length. A 12-core drill transect constrained by multiple 230Th ages shows the reef is composed of an ~2-m thick layer of coral clasts that has retrograded 100 m over its back-reef during the last 5.5 ka. These findings are consistent with a hurricane-control model of reef development where large waves trip and break over the mid-shelf slope break, triggering rapid energy dissipation and thus limiting how far upslope individual waves can fragment corals and transport clasts. As SL rises and water depth increases, energy dissipation during wave-breaking is reduced, extending the clast-transport limit, thus leading to reef retrogradation. This hurricane model may be applicable to a large sub-set of fringing reefs in the tropical Western-Atlantic necessitating a reappraisal of their accretion rates and response to future SL rise

Characterization of Available Light for Seagrass and Patch Reef Productivity in Sugarloaf Key, Lower Florida Keys

Light availability is an important factor driving primary productivity in benthic ecosystems, but in situ and remote sensing measurements of light quality are limited for coral reefs and seagrass beds. We evaluated the productivity responses of a patch reef and a seagrass site in the Lower Florida Keys to ambient light availability and spectral quality. In situ optical properties were characterized utilizing moored and water column bio-optical and hydrographic measurements. Net ecosystem productivity (NEP) was also estimated for these study sites using benthic productivity chambers. Our results show higher spectral light attenuation and absorption, and lower irradiance during low tide in the patch reef, tracking the influx of materials from shallower coastal areas. In contrast, the intrusion of clearer surface Atlantic Ocean water caused lower values of spectral attenuation and absorption, and higher irradiance in the patch reef during high tide. Storms during the studied period, with winds \u3e10 m·s−1, caused higher spectral attenuation values. A spatial gradient of NEP was observed, from high productivity in the shallow seagrass area, to lower productivity in deeper patch reefs. The highest daytime NEP was observed in the seagrass, with values of almost 0.4 g·O2·m−2·h−1. Productivity at the patch reef area was lower in May than during October 2012 (mean = 0.137 and 0.177 g·O2·m−2·h−1, respectively). Higher photosynthetic active radiation (PAR) levels measured above water and lower light attenuation in the red region of the visible spectrum (~666 to ~699 nm) had a positive correlation with NEP. Our results indicate that changes in light availability and quality by suspended or resuspended particles limit benthic productivity in the Florida Keys