Deeper coral reefs experience reduced temperatures and light and are often shielded from localized anthropogenic stressors such as pollution and fishing. The deep reef refugia hypothesis posits that light-dependent stony coral species at deeper depths are buffered from thermal stress and will avoid bleaching-related mass mortalities caused by increasing sea surface temperatures under climate change. This hypothesis has not been tested because data collection on deeper coral reefs is difficult. Here we show that deeper (mesophotic) reefs, 30-75 m depth, in the Caribbean are not refugia because they have lower bleaching threshold temperatures than shallow reefs. Over two thermal stress events, mesophotic reef bleaching was driven by a bleaching threshold that declines 0.26 °C every +10 m depth. Thus, the main premise of the deep reef refugia hypothesis that cooler environments are protective is incorrect; any increase in temperatures above the local mean warmest conditions can lead to thermal stress and bleaching. Thus, relatively cooler temperatures can no longer be considered a de facto refugium for corals and it is likely that many deeper coral reefs are as vulnerable to climate change as shallow water reefs.

Space-use by aquatic ectotherms is closely linked to environmental factors such as temperature due to thermal-mediated metabolism and energy requirements. These factors are important, as they may alter an animal’s exposure to food/predators, hinder physiological function, increase competitive interactions, or even prompt population or biodiversity loss. Using general linear mixed-effects models, we investigated the influence of medium-term (months-years) environmental (diel period, water temperature, season, wind speed, air pressure, habitat type) and biological (turtle size) variation on space-use metrics for the Critically Endangered hawksbill sea turtle Eretmochelys imbricata, including dive duration, activity space, and rate of movement. We tracked 17 resident juveniles between August 2015 and May 2018 with a compact acoustic telemetry array (35-41 receivers in ~1 km2) in Brewers Bay, US Virgin Islands. Diel differences in space-use were significant and highlighted periods of relative inactivity (e.g. resting) during the night and activity (e.g. foraging) during the day. Water temperature was also an important covariate influencing behavior leading to shorter dive durations and higher rates of movement in warmer temperatures. High contribution of random effects (individual and year) to model variation was also apparent, suggesting that juvenile hawksbills can operate outside the relatively narrow environmental range experienced within the study area. Nevertheless, ongoing climate trends (e.g. warmer temperatures and more extreme weather events) pose a significant concern for hawksbill populations, as juveniles spend their developmental period in shallow nearshore areas where environmental impacts will likely be greatest.

Marine Spatial Planning (MSP) provides a process that uses spatial data and models to evaluate environmental, social, economic, cultural, and management trade-offs when siting (i.e., strategically locating) ocean industries. Aquaculture is the fastest-growing food sector in the world. The United States (U.S.) has substantial opportunity for offshore aquaculture development given the size of its exclusive economic zone, habitat diversity, and variety of candidate species for cultivation. However, promising aquaculture areas overlap many protected species habitats. Aquaculture siting surveys, construction, operations, and decommissioning can alter protected species habitat and behavior. Additionally, aquaculture-associated vessel activity, underwater noise, and physical interactions between protected species and farms can increase the risk of injury and mortality. In 2020, the U.S. Gulf of Mexico was identified as one of the first regions to be evaluated for offshore aquaculture opportunities as directed by a Presidential Executive Order. We developed a transparent and repeatable method to identify aquaculture opportunity areas (AOAs) with the least conflict with protected species. First, we developed a generalized scoring approach for protected species that captures their vulnerability to adverse effects from anthropogenic activities using conservation status and demographic information. Next, we applied this approach to data layers for eight species listed under the Endangered Species Act, including five species of sea turtles, Rice’s whale, smalltooth sawfish, and giant manta ray. Next, we evaluated four methods for mathematically combining scores (i.e., Arithmetic mean, Geometric mean, Product, Lowest Scoring layer) to generate a combined protected species data layer. The Product approach provided the most logical ordering of, and the greatest contrast in, site suitability scores. Finally, we integrated the combined protected species data layer into a multi-criteria decision-making modeling framework for MSP. This process identified AOAs with reduced potential for protected species conflict. These modeling methods are transferable to other regions, to other sensitive or protected species, and for spatial planning for other ocean-uses.

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Interest and growth in marine aquaculture are increasing around the world, and with it, advanced spatial planning approaches are needed to find suitable locations in an increasingly crowded ocean. Standard spatial planning approaches, such as a Multi-Criteria Decision Analysis (MCDA), may be challenging and time consuming to interpret in heavily utilized ocean spaces. Spatial autocorrelation, a statistical measure of spatial dependence, may be incorporated into the planning framework, which provides objectivity and assistance with the interpretation of spatial analysis results. Here, two case studies highlighting applications of spatial autocorrelation analyses in the northeast region of the United States of America are presented. The first case study demonstrates the use of a local indicator of spatial association analysis within a relative site suitability analysis-a variant of a MCDA-for siting a mussel longline farm. This case study statistically identified 17% of the area as highly suitable for a mussel longline farm, relative to other locations in the area of interest. The use of a clear, objective, and efficient analysis provides improved confidence for industry, coastal managers, and stakeholders planning marine aquaculture. The second case study presents an incremental spatial autocorrelation analysis with Moran's I that is performed on modeled and remotely sensed oceanographic data sets (e.g., chlorophyll a, sea surface temperature, and current speed). The results are used to establish a maximum area threshold for each oceanographic variable within the online decision support tool, OceanReports, which performs an automated spatial analysis for a user-selected area (i.e., drawn polygon) of ocean space. These thresholds provide users guidance and summary statistics of relevant oceanographic information for aquaculture planning. These two case studies highlight practical uses and the value of spatial autocorrelation analyses to improve the siting process for marine aquaculture.

Grenada is highly dependent on coral reefs as a source of food and to support tourism. Local and global environmental stressors threaten these reefs. Legislation was created for this MPA in 2001, permanent mooring buoys were deployed in 2009 and enforcement of fishing restrictions began in 2010. Initiatives to address point and nonpoint source pollution from the land have recently begun, aimed at reducing stress on reef area. This study documents benthic cover and fish populations associated with reefs in a Marine Protected Area (MPA) along Grenada's southwest coast from 2008 through 2012. Both Point Line Intercept and Photo Quadrat methods were used to assess benthic cover along permanent 30m transects (8 in and 12 outside the area) annually. Fish and Diadema antillarum urchin relative abundance were determined based on 2m wide belt surveys along the same transects. The predominant substrate cover was algae, ranging from 41% in 2009 to 74.2% in 2011. A general trend of increasing algal cover was noted. Combined annual survey results prior (2008)(2009)(2010) and after controls were implemented (2011-2012) showed a significant increase in algal cover. The predominant algal form was macroalgae comprising 65.4% -90.8% of total algae. Live hard coral percent cover ranged from 8.7% to 21.1%. Little annual variation was observed in percent live coral cover. Branching corals (34.1% -52.3% of total living hard coral) were the most common. Of the 19 living hard coral species identified, Porites porites (21%-23%) and Porites astreoides (20%) dominated percentage composition. Madracis mirabilis contributed 21% of total live hard coral outside the MPA but only 8.7% in the MPA. Of the 63 species of fish identified in the study areas Chromis spp. (71.5% -46%) was the dominant group. Wrasse had a significant increase from 6.9% in 2008 to 21.5% in 2010 inside the MPA with a similar increase peaking in 2011 outside the MPA. There was a noticeable (though not statistically significant) increase in piscivorous fishes in the MPA in 2012. This is a promising indication that fishing restrictions in the MPA may be having an effect. Diadema antillarum density was low, ranging from 4.58 to 0.21 urchins/100m 2 outside and 0.28 to 0.10 urchins/100m 2 inside despite a stocking attempt in the area in 2011. Rev. Biol. Trop. 62 (Suppl. 3): 273-286. Epub 2014 September 01.

<span>Un estudio sobre poblaciones bentónicas y de peces fue realizado en cinco localidades en la zona costera en el suroeste de Grenada entre 2008 y 2010. Dos sitios se ubicaron en una Área Marina Portegida (AMP) recientemente creada. Para determinar la cobertura se utilizaron foto-cuadrantes (FQ) y transectos de intersección de puntos (TIP). Las algas fueron el principal componente del bentos, aumentando significativamente de 45,9% en 2008 a 52,7% en 2010 (TIP). Las algas también fueron predominantes (61,9%-59,3) en los FQ, aunque las diferencias anuales no fueron significativas. La cobertura de corales pétreos tenía un ámbito de 16,5% a 15,4% (TIP) y de 11,4% a 12,0% (FQ), sin diferencias significativas entre años. Los corales ramificados e incrustantes fueron más frecuentes que los corales masivos. En los tres años no hubo diferencias significativas entre las AMPs y las áreas no protegidas. La abundancia relativa de peces a lo largo de un transecto de 30x2m no varió significativamente entre los años, sin embargo, la densidad de peces decreció significativamente a través de los años, para los grupos principales.<em> Chromis</em> spp. predominó con 65,2% en 2008 y 49,8% en 2012, seguido por damiselas territoriales, 11,1% y 15,5%, y los lábridos aumentaron de 7,3% a 15,5%. Tanto la coberura del sustrato como los datos de peces indican una comunidad estable pero degradada. Sondeos anuales están planeados para el futuro. Los datos existentes y futuros de este proyecto serán muy útiles para determinar la eficacia de la gestión de las AMPs y el estado de salud de los sistemas arrecifales de Grenada.</span>

Nassau grouper (Epinephelus striatus, Serranidae) were one of the most important fishery species in the Caribbean, but are now listed as critically endangered. Population collapse in most places occurred primarily by fishers targeting their spawning aggregation sites, where thousands of fish gathered during full moon periods from December to April. Identifying management options for protecting this vulnerable period is crucial for their survival. In the US Virgin Islands, we tagged 24 Nassau grouper with acoustic transmitters at a fish spawning aggregation (FSA) site called the Grammanik Bank, a 1.5 km2, marine protected area (MPA) closed each year from February to April. We tracked their movements over a seven-year period and found that the small MPA protected Nassau grouper only 65% of time during the spawning season. Nassau grouper arrived at the FSA from January to May, with a peak in March, and made daily roundtrip migrations (1-25 km) from the FSA site. Females swam twice as far as males, while males were more sedentary and remained longer (22 d) at the FSA than females (9 d); behavioural characteristics that may cause differential bycatch mortality among sexes. We also found nearly half of all fish were temporary residents within 5 km of the FSA site for 2 to 6 months after the spawning season. This mismatch of MPA size and timing of closed season provided the impetus for developing new guidelines for protection. The large acoustic array allowed us to calculate spatially relevant areas useful for conservation including courtship arena (1.2 km2), staging area (4.7 km2) and primary migration pathways (9.6 km2) used by Nassau grouper during spawning season. To improve conservation goals of this endangered species, increasing the Grammanik Bank seasonal closure to five months and its size to 6.4 km2 would increase protection to &gt;96%. These spatial and temporal changes to existing management regulations incorporate the best available data to improve conservation goals by reducing potential bycatch mortality, eliminating disturbance of spawning fish, and protecting critical spawning habitat for Nassau grouper. These guidelines may also be applied more broadly to other Nassau grouper FSA sites located on large insular or continental shelfs areas throughout the Caribbean.