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St. Martin’s Island is a small sedimentary island situated at the southernmost part of Bangladesh (20°37.6′ N and 92°19.3′ E). The island is surrounded by rocky reefs composed of Neogene bedrock consisting of moderately hard and soft sandstones and conglomerates belonging to the Tipam Sandstone (Islam in Bangladesh J Univ Sheffield Geol Soc 7:269–275, 1980). The rocky reefs are covered by fields of conglomerate boulders and calcareous concretions that provide a suitable substrate for coral settlement and the establishment of coral communities. Before 1997 it was reported that St. Martin’s Island was a coral island surrounded by coral reefs (Ahmed in Bangladesh J Environ Sci 1:67–73, 1995; Anwar in National workshop on coastal area resource development and management, Part II. CARDMA, BRAC Printers Bangladesh, Dhaka, pp 36–66, 1988; UNEP/IUCN in Indian Ocean, Red Sea and Gulf. UNEP regional seas and bibliographies. IUCN, Gland, 1988). However, the first underwater survey conducted in 1997 did not find any evidence of coral reefs (Tomascik in Management plan for coral resources of Narikel Jinjira (St. Martin's Island). National Conservation Strategy Implementation Project-1, Ministry of Environment and Forest, Government of the People’s Republic of Bangladesh, p 125, 1997). The island has become an important tourism destination and concerns have been raised about the impact of local development on its coral resources (Tomascik 1997). Recently a paper was published on the degradation of coral reefs on St. Martin’s Island (Gazi et al. in Ocean Sci J 55(3):419–431, 2020) that makes many factually incorrect assertions. The rocky reefs that surround the island have been misclassified by Gazi et al. (2020) as “coral reefs”. Here, we discuss Gazi et al. (2020) and examine if the results and conclusions provide factual evidence of spatiotemporal coral reef degradation.

Giant kelp and bull kelp forests are increasingly at risk from marine heatwave events, herbivore outbreaks, and the loss or alterations in the behavior of key herbivore predators. The dynamic floating canopy of these kelps is well-suited to study via satellite imagery, which provides high temporal and spatial resolution data of floating kelp canopy across the western United States and Mexico. However, the size and complexity of the satellite image dataset has made ecological analysis difficult for scientists and managers. To increase accessibility of this rich dataset, we created Kelpwatch, a web-based visualization and analysis tool. This tool allows researchers and managers to quantify kelp forest change in response to disturbances, assess historical trends, and allow for effective and actionable kelp forest management. Here, we demonstrate how Kelpwatch can be used to analyze long-term trends in kelp canopy across regions, quantify spatial variability in the response to and recovery from the 2014 to 2016 marine heatwave events, and provide a local analysis of kelp canopy status around the Monterey Peninsula, California. We found that 18.6% of regional sites displayed a significant trend in kelp canopy area over the past 38 years and that there was a latitudinal response to heatwave events for each kelp species. The recovery from heatwave events was more variable across space, with some local areas like Bahía Tortugas in Baja California Sur showing high recovery while kelp canopies around the Monterey Peninsula continued a slow decline and patchy recovery compared to the rest of the Central California region. Kelpwatch provides near real time spatial data and analysis support and makes complex earth observation data actionable for scientists and managers, which can help identify areas for research, monitoring, and management efforts.

Spatial synchrony is a ubiquitous and important feature of population dynamics, but many aspects of this phenomenon are not well understood. In particular, it is largely unknown how multiple environmental drivers interact to determine synchrony via Moran effects, and how these impacts vary across spatial and temporal scales. Using new wavelet statistical techniques, we characterised synchrony in populations of giant kelp Macrocystis pyrifera, a widely distributed marine foundation species, and related synchrony to variation in oceanographic conditions across 33 years (1987-2019) and 900 km of coastline in California, USA. We discovered that disturbance (storm-driven waves) and resources (seawater nutrients)-underpinned by climatic variability-act individually and interactively to produce synchrony in giant kelp across geography and timescales. Our findings demonstrate that understanding and predicting synchrony, and thus the regional stability of populations, relies on resolving the synergistic and antagonistic Moran effects of multiple environmental drivers acting on different timescales.

Spatial synchrony may be tail-dependent, that is, stronger when populations are abundant than scarce, or vice-versa. Here, 'tail-dependent' follows from distributions having a lower tail consisting of relatively low values and an upper tail of relatively high values. We present a general theory of how the distribution and correlation structure of an environmental driver translates into tail-dependent spatial synchrony through a non-linear response, and examine empirical evidence for theoretical predictions in giant kelp along the California coastline. In sheltered areas, kelp declines synchronously (lower-tail dependence) when waves are relatively intense, because waves below a certain height do little damage to kelp. Conversely, in exposed areas, kelp is synchronised primarily by periods of calmness that cause shared recovery (upper-tail dependence). We find evidence for geographies of tail dependence in synchrony, which helps structure regional population resilience: areas where population declines are asynchronous may be more resilient to disturbance because remnant populations facilitate reestablishment.

Kelp forests are globally important and highly productive ecosystems, yet their persistence and protection in the face of climate change and human activity are poorly known. Here, we present a 35-year time series of high-resolution satellite imagery that maps the distribution and persistence of giant kelp (Macrocystis pyrifera) forests along ten degrees of latitude in the Northeast Pacific Ocean. We find that although 7.7% of giant kelp is protected by marine reserves, when accounting for persistence only 4% of kelp is present and protected. Protection of giant kelp decreases southerly from 20.9% in Central California, USA, to less than 1% in Baja California, Mexico, which likely exacerbates kelp vulnerability to marine heatwaves in Baja California. We suggest that a two-fold increase in the area of kelp protected by marine reserves is needed to fully protect persistent kelp forests and that conservation of climate-refugia in Baja California should be a priority. Giant kelp forests in the Northeast Pacific Ocean are inadequately represented in marine protected areas, which increases their vulnerability to marine heatwaves, according to a 35-year satellite image time series.

Coastal ecosystems are rapidly changing due to human-caused global warming, rising sea level, changing circulation patterns, sea ice loss, and acidification that in turn alter the productivity and composition of marine biological communities. In addition, regional pressures associated with growing human populations and economies result in changes in infrastructure, land use, and other development; greater extraction of fisheries and other natural resources; alteration of benthic seascapes; increased pollution; and eutrophication. Understanding biodiversity is fundamental to assessing and managing human activities that sustain ecosystem health and services and mitigate humankind’s indiscretions. Remote-sensing observations provide rapid and synoptic data for assessing biophysical interactions at multiple spatial and temporal scales and thus are useful for monitoring biodiversity in critical coastal zones. However, many challenges remain because of complex bio-optical signals, poor signal retrieval, and suboptimal algorithms. Here, we highlight four approaches in remote sensing that complement the Marine Biodiversity Observation Network (MBON). MBON observations help quantify plankton functional types, foundation species, and unique species habitat relationships, as well as inform species distribution models. In concert with in situ observations across multiple platforms, these efforts contribute to monitoring biodiversity changes in complex coastal regions by providing oceanographic context, contributing to algorithm and indicator development, and creating linkages between long-term ecological studies, the next generations of satellite sensors, and marine ecosystem management.

Climate change is responsible for increased frequency, intensity, and duration of extreme events, such as marine heatwaves (MHWs). Within eastern boundary current systems, MHWs have profound impacts on temperature-nutrient dynamics that drive primary productivity. Bull kelp (Nereocystis luetkeana) forests, a vital nearshore habitat, experienced unprecedented losses along 350 km of coastline in northern California beginning in 2014 and continuing through 2019. These losses have had devastating consequences to northern California communities, economies, and fisheries. Using a suite of in situ and satellite-derived data, we demonstrate that the abrupt ecosystem shift initiated by a multi-year MHW was preceded by declines in keystone predator population densities. We show strong evidence that northern California kelp forests, while temporally dynamic, were historically resilient to fluctuating environmental conditions, even in the absence of key top predators, but that a series of coupled environmental and biological shifts between 2014 and 2016 resulted in the formation of a persistent, altered ecosystem state with low primary productivity. Based on our findings, we recommend the implementation of ecosystem-based and adaptive management strategies, such as (1) monitoring the status of key ecosystem attributes: kelp distribution and abundance, and densities of sea urchins and their predators, (2) developing management responses to threshold levels of these attributes, and (3) creating quantitative restoration suitability indices for informing kelp restoration efforts., Meredith McPherson et al. use a 34-year time series of satellite and in situ derived data to study bull kelp forests of northern California and demonstrate the ecosystem shifts following a marine heatwave event between 2014 and 2016. The results show that increased herbivory by sea urchins due to the loss of a predator reduced bull kelp forest resistance to fluctuating environmental conditions and point to the importance of ecosystem-based and adaptive management strategies.

Satellite and aerial imagery have been used extensively for mapping the abundance and distribution of giant kelp (Macrocystis pyrifera) in southern California. There is now great potential for using unoccupied aerial vehicles (UAVs) to map kelp canopy at very high resolutions. However, tides and currents have been shown to affect the amount of floating kelp canopy on the water surface, and the impacts of these processes on remotely sensed kelp estimates in this region have not been fully quantified. UAVs were used to map fine-scale changes in canopy area due to tidal height and current speed at kelp forests off the coast of Palos Verdes, CA and Santa Barbara, CA. An automated method for detecting kelp canopy was developed that was 67% accurate using red-green-blue (RGB) UAV imagery and 93% accurate using multispectral UAV imagery across a range of weather, ocean, and illumination conditions. Increases in tidal height of 1 m reduced the amount of floating kelp canopy by 15% in Santa Barbara and by over 30% in Palos Verdes. The effect of current speed on visible kelp canopy was inconclusive, but there was a trend towards lower canopy area with increased current speed. Therefore, while tidal height and current speed can introduce significant variability to estimates of kelp abundance, the magnitude of this variability is site specific. Still, UAVs are a valuable tool for mapping of kelp canopy and can provide greater spatial resolution and temporal coverage than is possible from many satellite sensors. This data can provide insight into the patterns and drivers of high frequency fluctuations in kelp abundance.

In most regions, the distribution of marine forests and the efficacy of their protection is unknown. We mapped the persistence of giant kelp forests across ten degrees of latitude in the Northeast Pacific Ocean and found that 7.7% of giant kelp is fully protected, with decreasing percentages from north to south. Sustainability goals should prioritize kelp mapping and monitoring, while protection and climate adaption targets should account for habitat dynamics.

Giant kelp populations that support productive and diverse coastal ecosystems at temperate and subpolar latitudes of both hemispheres are vulnerable to changing climate conditions as well as direct human impacts. Observations of giant kelp forests are spatially and temporally uneven, with disproportionate coverage in the northern hemisphere, despite the size and comparable density of southern hemisphere kelp forests. Satellite imagery enables the mapping of existing and historical giant kelp populations in understudied regions, but automating the detection of giant kelp using satellite imagery requires approaches that are robust to the optical complexity of the shallow, nearshore environment. We present and compare two approaches for automating the detection of giant kelp in satellite datasets: one based on crowd sourcing of satellite imagery classifications and another based on a decision tree paired with a spectral unmixing algorithm (automated using Google Earth Engine). Both approaches are applied to satellite imagery (Landsat) of the Falkland Islands or Islas Malvinas (FLK), an archipelago in the southern Atlantic Ocean that supports expansive giant kelp ecosystems. The performance of each method is evaluated by comparing the automated classifications with a subset of expert-annotated imagery (8 images spanning the majority of our continuous timeseries, cumulatively covering over 2,700 km of coastline, and including all relevant sensors). Using the remote sensing approaches evaluated herein, we present the first continuous timeseries of giant kelp observations in the FLK region using Landsat imagery spanning over three decades. We do not detect evidence of long-term change in the FLK region, although we observe a recent decline in total canopy area from 2017–2021. Using a nitrate model based on nearby ocean state measurements obtained from ships and incorporating satellite sea surface temperature products, we find that the area of giant kelp forests in the FLK region is positively correlated with the nitrate content observed during the prior year. Our results indicate that giant kelp classifications using citizen science are approximately consistent with classifications based on a state-of-the-art automated spectral approach. Despite differences in accuracy and sensitivity, both approaches find high interannual variability that impedes the detection of potential long-term changes in giant kelp canopy area, although recent canopy area declines are notable and should continue to be monitored carefully.

Photoautotrophs vary the concentration of photosynthetic pigments in response to changing environmental conditions. In the ocean, the chlorophyll a to carbon ratio (Chl:C) has been used as a proxy for the physiological condition of phytoplankton, and there is laboratory evidence that the growth rate of juvenile giant kelp (Macrocystis pyrifera), a coastal foundation species, is positively related to Chl:C under nutrient-limited conditions. We examined the relative roles of nutrients and light in determining Chl:C dynamics and if fluctuations in Chl:C were related to changes in canopy biomass and net primary production (NPP) from sites spanning 750 km of the California coast. Seventy percent of the variability in canopy Chl:C was explained by a combination of photosynthetically active radiation and seawater nitrate concentration. In the periodically nutrient-limited waters of the Southern California Bight, changes in Chl:C positively resembled changes in available nitrate, whereas Chl:C negatively tracked changes in light for the more nutrient-replete central California coastline. Values of Chl:C were positively related to residuals from an autoregressive model of kelp biomass at the southern California sites indicating that Chl:C is a proxy for physiological state of the kelp canopy. NPP estimated through correlations with kelp biomass and lagged Chl:C compared well to established field-based estimates. These results open the possibility of assessing giant kelp physiological condition from estimates of Chl:C modeled from sea surface irradiance and nitrate concentration, which in turn can be used to estimate giant kelp primary production over large spatial and temporal scales using future remote sensing technologies.

Species targeted by fishing often recover in abundance and size within marine protected areas (MPAs) resulting in increased reproductive potential. However, in some situations, concomitant changes in the abundance of predators, competitors, or prey within MPAs, or strong gradients in the surrounding environmental seascape may counteract the purported benefits making it more difficult to predict how species will respond to protection. We used a network of MPAs in California, spanning a large temperature gradient, to investigate the drivers of demographic variability in the commercially important red sea urchin Mesocentrotus franciscanus. We investigated how demographic metrics varied geographically in response to protection, temperature, and the main sea urchin resource, the giant kelp Macrocystis pyrifera. We found significant conservation benefits to this fished sea urchin within MPAs designated six years prior to the beginning of this study. Within MPAs, red sea urchins were generally larger resulting in greater adult biomass density and reproductive biomass density. In addition, kelp density was an important explanatory variable of all red sea urchin demographic traits examined (adult size, gonadosomatic index [GSI], density, adult biomass density, and reproductive biomass density). Kelp density was positively correlated with red sea urchin GSI and adult size, but the relationships with density, adult biomass density, and reproductive biomass density were complex and the directionality changed depending on the region (or environmental setting) examined. Our results demonstrate that kelp, red sea urchin reproduction, and the effects of spatial management on demographic processes are tightly coupled with the oceanographic regime.

Global-scale studies suggest that dryland ecosystems dominate an increasing trend in the magnitude and interannual variability of the land CO2 sink. However, such analyses are poorly constrained by measured CO2 exchange in drylands. Here we address this observation gap with eddy covariance data from 25 sites in the water-limited Southwest region of North America with observed ranges in annual precipitation of 100-1000 mm, annual temperatures of 2-25°C, and records of 3-10 years (150 site-years in total). Annual fluxes were integrated using site-specific ecohydrologic years to group precipitation with resulting ecosystem exchanges. We found a wide range of carbon sink/source function, with mean annual net ecosystem production (NEP) varying from -350 to +330 gCm-2 across sites with diverse vegetation types, contrasting with the more constant sink typically measured in mesic ecosystems. In this region, only forest-dominated sites were consistent carbon sinks. Interannual variability of NEP, gross ecosystem production (GEP), and ecosystem respiration (Reco ) was larger than for mesic regions, and half the sites switched between functioning as C sinks/C sources in wet/dry years. The sites demonstrated coherent responses of GEP and NEP to anomalies in annual evapotranspiration (ET), used here as a proxy for annually available water after hydrologic losses. Notably, GEP and Reco were negatively related to temperature, both interannually within site and spatially across sites, in contrast to positive temperature effects commonly reported for mesic ecosystems. Models based on MODIS satellite observations matched the cross-site spatial pattern in mean annual GEP but consistently underestimated mean annual ET by ~50%. Importantly, the MODIS-based models captured only 20-30% of interannual variation magnitude. These results suggest the contribution of this dryland region to variability of regional to global CO2 exchange may be up to 3-5 times larger than current estimates.

Kelp forests are among the world's most productive marine ecosystems, yet little is known about their biogeochemistry. This study presents a 14-month time series (July 2013–August 2014) of surface and benthic dissolved inorganic carbon and total alkalinity measurements, along with accompanying hydrographic measurements, from six locations within a central California kelp forest. We present ranges and patterns of variability in carbonate chemistry, including pH (7.70–8.33), pCO2 (172–952 µatm), and the aragonite saturation state, ΩAr (0.94–3.91). Surface-to-bottom gradients in CO2 system chemistry were as large as the spatial gradients throughout the bottom of the kelp forest. Dissolved inorganic carbon variability was the main driver of the observed CO2 system variability. The majority of spatial variability in the kelp forest can be explained by advection of cold, dense high-CO2 waters into the bottom of the kelp forest, with deeper sites experiencing high-CO2 conditions more frequently. Despite the strong imprint of advection on the biogeochemical variability of the kelp forest, surface waters were undersaturated with CO2 in the spring through fall, indicative of the strong role of photosynthesis on biogeochemical variability. We emphasize the importance of spatially distributed measurements for developing a process-based understanding of kelp forest ecosystem function in a changing climate.

Recruitment of marine fishes is largely determined by biological and environmental factors acting on early-life stages. Subtle changes in larval condition in response to their environment can result in order-of-magnitude differences in year-class-strength. Overlap of larval production and favorable feeding conditions drives recruitment for many temperate marine fishes, but challenges associated with studying marine larvae have made it difficult to assess how environmental processes act on individual larvae to affect their growth and survival. We conducted a 2-yr study in an upwelling system to assess the influence of regional productivity, temperature, and larval condition in explaining growth in rockfishes (Sebastes spp.). We employed otolith microstructure and satellite imagery to measure initial larval growth and estimate the productivity and temperature experienced by individuals to determine their relative importance in subsequent growth at metamorphosis. We compared model performance using indexed environmental conditions scaled over three different regions. In both years, net primary productivity explained the most variation in pre-metamorphic growth relative to temperature and initial growth. This relationship was consistent across spatial regions, although model fit was highest using indices scaled to the south continental shelf region. Recent settlement, juvenile recruitment, and individual growth were significantly higher in a year when productivity bloomed earlier and individual larvae experienced higher levels of productivity. Thus, this link between regional scale productivity, growth, and subsequent year-class strength supports the hypothesis that large-scale oceanographic processes stimulating upwelling and secondary production are primary drivers of larval growth and recruitment in rockfishes.

Atmospheric methanethiol (MeSHa), dimethyl sulfide (DMSa) and acetone (acetonea) were measured over biologically productive frontal waters in the remote South West Pacific Ocean in summertime 2012 during the Surface Ocean Aerosol Production (SOAP) voyage. MeSHa mixing ratios varied from below detection limit (a mixing ratios. MeSHa and DMSa were correlated over the voyage (R2 = 0.3, slope = 0.07) with a stronger correlation over a coccolithophore-dominated phytoplankton bloom (R2 = 0.5, slope 0.13). The diurnal cycle for MeSHa shows similar behaviour to DMSa with mixing ratios varying by a factor of ~ 2 according to time of day with the minimum levels of both MeSHa and DMSa occurring at around 16:00 hrs. A positive flux of MeSH was calculated for 3 different nights and ranged from 3.5–5.8 µmol m−2 day−1 corresponding to 14–24 % of the DMS flux (MeSH / (MeSH + DMS). Spearman rank correlations with ocean biogeochemical parameters showed a moderate to strong positive and highly significant relationship between both MeSHa and DMSa with seawater DMS (DMSsw), and a moderate correlation with total dimethylsulfoniopropionate (total DMSP). A positive correlation of acetonea with water temperature and negative correlation with nutrient concentrations is consistent with reports of acetone production in warmer subtropical waters. Positive correlations of acetonea with cryptophyte and eukaryotic phytoplankton numbers, and high molecular weight sugars and Chromophoric Dissolved Organic Matter (CDOM), suggest an organic source. This work points to a significant ocean source of MeSH, highlighting the need for further studies into the distribution and fate of MeSH, and suggests links between atmospheric acetone levels and biogeochemistry over the mid-latitude ocean. In addition, an intercalibration of DMSa at ambient levels using three independently calibrated instruments showed ~ 15–25 % higher mixing ratios from an Atmospheric Pressure Ionisation-Chemical Ionisation Mass Spectrometer (mesoCIMS) compared to a Gas Chromatograph with Sulfur Chemiluminescence Detector (GC-SCD) and proton transfer reaction mass spectrometer (PTR-MS). PTR-MS and mesoCIMS showed similar temporal behaviour with differences in ambient mixing ratios likely influenced by the DMSa gradient above the sea surface.

A critical tool in assessing ecosystem change is the analysis of long-term data sets, yet such information is generally sparse and often unavailable for many habitats. Kelp forests are an example of rapidly changing ecosystems that are in most cases data poor. Because kelp forests are highly dynamic and have high intrinsic interannual variability, understanding how regional-scale drivers are driving kelp populations-and particularly how kelp populations are responding to climate change-requires long-term data sets. However, much of the work on kelp responses to climate change has focused on just a few, relatively long-lived, perennial, canopy-forming species. To understand how kelp populations with different life history traits are responding to climate-related variability, we leverage 35 yr of Landsat satellite imagery to track the population size of an annual, ruderal kelp, Nereocystis luetkeana, across Oregon. We found high levels of interannual variability in Nereocystis canopy area and varying population trajectories over the last 35 yr. Surprisingly, Oregon Nereocystis population sizes were unresponsive to a 2014 marine heat wave accompanied by increases in urchin densities that decimated northern California Nereocystis populations. Some Oregon Nereocystis populations have even increased in area relative to pre-2014 levels. Analysis of environmental drivers found that Nereocystis population size was negatively correlated with estimated nitrate levels and positively correlated with winter wave height. This pattern is the inverse of the predicted relationship based on extensive prior work on the perennial kelp Macrocystis pyrifera and may be related to the annual life cycle of Nereocystis. This article demonstrates (1) the value of novel remote sensing tools to create long-term data sets that may challenge our understanding of nearshore marine species and (2) the need to incorporate life history traits into our theory of how climate change will shape the ocean of the future.

The use of small Unmanned Aircraft Systems (sUAS ) as platforms for data capture has rapidly increased in recent years. However, while there has been significant investment in improving the aircraft, sensors, operations, and legislation infrastructure for such, little attention has been paid to supporting the management of the complex data capture pipeline sUAS involve. This paper reports on the outcomes of a four-year-long community-engagement-based investigation into what tools, practices, and challenges currently exist for particularly researchers using sUAS as data capture platforms. The key results of this effort are: (1) sUAS captured data – as a set that is rapidly growing to include data in a wide range of Physical and Environmental Sciences, Engineering Disciplines, and many civil and commercial use cases – is characterised as both sharing many traits with traditional remote sensing data and also as exhibiting – as common across the spectrum of disciplines and use cases – novel characteristics that require novel data support infrastructure. And (2), given this characterization of sUAS data and its potential value in the identified wide variety of use case, we outline eight challenges that need to be addressed in order for the full value of sUAS captured data to be realized. We then conclude that there would be significant value gained and costs saved across both commercial and academic sectors if the global sUAS user and data management communities were to address these challenges in the immediate to near future, so as to extract the maximal value of sUAS captured data for the lowest long-term effort and monetary cost.

The growth of marine aquaculture over the 21st century is a promising venture for food security because of its potential to fulfill the seafood deficit in the future. However, to maximize the use of marine space and its resources, the spatial planning of marine aquaculture needs to consider the regimes of climate variability in the oceanic environment, which are characterized by large-amplitude interannual to decadal fluctuations. It is common to see aquaculture spatial planning schemes that do not take variability into consideration. This assumption may be critical for management and for the expansion of marine aquaculture, because projects require investments of capital and need to be profitable to establish and thrive. We analyze the effect of climate variability on the profitability of hypothetical mussel aquaculture systems in the Southern California Bight. Using historical environmental data from 1981 to 2008, we combine mussel production and economics models at different sites along the coast to estimate the Net Present Value as an economic indicator of profitability. We find that productivity of the farms exhibits a strong coherent behavior with marketed decadal fluctuations that are connected to climate of the North Pacific Basin, in particular linked to the phases of the North Pacific Gyre Oscillation (NPGO). This decadal variability has a strong impact on profitability both temporally and spatially, and emerges because of the mussels’ dependence on multiple oceanic environmental variables. Depending on the trend of the decadal regimes in mussel productivity and the location of the farms, these climate fluctuations will affect cost recovery horizon and profitability for a given farm. These results suggest that climate variability should be taken into consideration by managers and investors on decision making to maximize profitability.

Ecological theory predicts that demographic connectivity structures the dynamics of local populations within metapopulation systems, but empirical support has been constrained by major limitations in data and methodology. We tested this prediction for giant kelp Macrocystis pyrifera, a key habitat-forming species in temperate coastal ecosystems worldwide, in southern California, USA. We combined a long-term (22 years), large-scale (~500 km coastline), high-resolution census of abundance with novel patch delineation methods and an innovative connectivity measure incorporating oceanographic transport and source fecundity. Connectivity strongly predicted local dynamics (well-connected patches had lower probabilities of extinction and higher probabilities of colonization, leading to greater likelihoods of occupancy) but this relationship was mediated by patch size. Moreover, the relationship between connectivity and local population dynamics varied over time, possibly due to temporal variation in oceanographic transport processes. Surprisingly, connectivity had a smaller influence on colonization relative to extinction, possibly because local ecological factors differ greatly between extinct and extant patches. Our results provide the first comprehensive evidence that southern California giant kelp populations function as a metapopulation system, challenging the view that populations of this important foundation species are governed exclusively by self-replenishment.

Este artículo contiene 23 páginas, 6 figuras, 6 tablas., The kelp forests of southern South America are some of the least disturbed on the planet. The remoteness of this region has, until recently, spared it from many of the direct anthropogenic stressors that have negatively affected these ecosystems elsewhere. Re-surveys of 11 locations at the easternmost extent of Tierra del Fuego originally conducted in 1973 showed no significant differences in the densities of adult and juvenile Macrocystis pyrifera kelp or kelp holdfast diameter between the two survey periods. Additionally, sea urchin assemblage structure at the same sites were not significantly different between the two time periods, with the dominant species Loxechinus albus accounting for 66.3% of total sea urchin abundance in 2018 and 61.1% in 1973. Time series of Landsat imagery of the region from 1998 to 2018 showed no long-term trends in kelp canopy over the past 20 years. However, ~ 4-year oscillations in canopy fraction were observed and were strongly and negatively correlated with the NOAA Multivariate ENSO index and sea surface temperature. More extensive surveying in 2018 showed significant differences in benthic community structure between exposed and sheltered locations. Fish species endemic to the Magellanic Province accounted for 73% of all nearshore species observed and from 98–100% of the numerical abundance enumerated at sites. Fish assemblage structure varied significantly among locations and wave exposures. The recent creation of the Yaganes Marine Park is an important step in protecting this unique and biologically rich region; however, the nearshore waters of the region are currently not included in this protection. There is a general lack of information on changes in kelp forests over long time periods, making a global assessment difficult. A complete picture of how these ecosystems are responding to human pressures must also include remote locations and locations with little to no impact., We received fundingfrom The Brooks Foundation,The Keith CampbellFoundationfor the Environment, The Case Foundation,Leonardo DiCaprio Foundation,Davidoff, The Don Quixote Foundation,Roger and Rosemary Enrico Foundation,HelmsleyCharitable Trust, Lindblad Expeditions-National Geographic Fund,Philip Stephenson Foundation,Vicki and Roger Sant, The Waitt Foundation,and The National Geographic Society.

Global, repeat satellite imagery serves as an essential tool to understand ecological patterns and processes over diverse temporal and spatial scales. Recently, the use of spaceborne imagery has become indispensable for monitoring giant kelp, a globally distributed foundation species that displays variable seasonal and interannual dynamics. In order to develop and maintain a continuous and spatially expansive time series, we describe a fully automated protocol to classify giant kelp canopy biomass across three Landsat sensors. This required correcting kelp canopy estimates to account for changes in the spectral response functions between the three sensors by simulating data using hyperspectral imagery. Combining multiple sensors also necessitated the use of an extended (15 year) time series of diver estimated kelp biomass to validate each sensor. We also describe a novel gap filling technique using known spatial scales of kelp biomass synchrony to correct for missing data due to the Enhanced Thematic Mapper Plus scan line corrector failure. These developments have led to a publicly available 34-year, seasonal time series of kelp canopy biomass across ~1500 km of California coastline. We then use this time series to examine the role of temporal and spatial scale on the detection of long-term biomass trends. We found that kelp canopy biomass trends are associated with trends in low frequency marine climate oscillations, like the North Pacific Gyre Oscillation. Long-term (~20 year) increases in the state of the North Pacific Gyre Oscillation have led to a cooler, nutrient-rich environment that benefits the growth of giant kelp across a large portion of the kelp biomass time series, however recent warming events have led to weak, or nonexistent trends over the length of the time series. The cyclical nature of these low frequency marine climate oscillations complicates the detection of trends that may be associated with anthropogenic climate change. A longer and continuous time series is needed to analyze long-term canopy biomass trends outside of natural low frequency climate variability for giant kelp ecosystems along the coast of California, if we are to make accurate assessments of the impacts of climate change.

Author(s): Kelly, Patrick T; Bell, Tom; Reisinger, Alexander J; Spanbauer, Trisha L; Bortolotti, Lauren E; Brentrup, Jennifer A; Briseno-Avena, Christian; Dong, Xiaoli; Flanagan, Alison M; Follett, Elizabeth M; Grosse, Julia; Guy-Haim, Tamar; Holgerson, Meredith A; Hovel, Rachel A; Luo, Jessica Y; Millette, Nicole C; Mine, Aric; Muscarella, Mario E; Oliver, Samantha K; Smith, Heidi J

© 2017 The Author(s). Background: Mesocosm experiments have become increasingly popular in climate change research as they bridge the gap between small-scale, less realistic, microcosm experiments, and large-scale, more complex, natural systems. Characteristics of aquatic mesocosm designs (e.g., mesocosm volume, study duration, and replication) vary widely, potentially affecting the magnitude and direction of effect sizes measured in experiments. In this global systematic review we aim to identify the type, direction and strength of climate warming effects on aquatic species, communities and ecosystems in mesocosm experiments. Furthermore, we will investigate the context-dependency of the observed effects on several a priori determined effect moderators (ecological and methodological). Our conclusions will provide recommendations for aquatic scientists designing mesocosm experiments, as well as guidelines for interpretation of experimental results by scientists, policy-makers and the general public. Methods: We will conduct a systematic search using multiple online databases to gather evidence from the scientific literature on the effects of warming experimentally tested in aquatic mesocosms. Data from relevant studies will be extracted and used in a random effects meta-analysis to estimate the overall effect sizes of warming experiments on species performance, biodiversity and ecosystem functions. Experimental characteristics (e.g., mesocosm size and shape, replication-level, experimental duration and design, biogeographic region, community type, crossed manipulation) will be further analysed using subgroup analyses.

Marine spatial planning (MSP) seeks to reduce conflicts and environmental impacts, and promote sustainable use of marine ecosystems. Existing MSP approaches have successfully determined how to achieve target levels of ocean area for particular uses while minimizing costs and impacts, but they do not provide a framework that derives analytical solutions in order to co-ordinate siting of multiple uses while balancing the effects of planning on each sector in the system. We develop such a framework for guiding offshore aquaculture (bivalve, finfish, and kelp farming) development in relation to existing sectors and environmental concerns (wild-capture fisheries, viewshed quality, benthic pollution, and disease spread) in California, USA. We identify > 250,000 MSP solutions that generate significant seafood supply and billions of dollars in revenue with minimal impacts (often, Marine spatial planning is used to co-ordinate multiple ocean uses, and is frequently informed by tradeoffs and composite metrics. Here, Lester et al. introduce an approach that plans for multiple uses simultaneously whilst balancing individual objectives, using a case study of aquaculture development in California.

The desire to use sentinel species as early warning indicators of impending climate change effects on entire ecosystems is attractive, but we need to verify that such approaches have sound biological foundations. A recent large-scale warming event in the North Pacific Ocean of unprecedented magnitude and duration allowed us to evaluate the sentinel status of giant kelp, a coastal foundation species that thrives in cold, nutrient-rich waters and is considered sensitive to warming. Here, we show that giant kelp and the majority of species that associate with it did not presage ecosystem effects of extreme warming off southern California despite giant kelp's expected vulnerability. Our results challenge the general perception that kelp-dominated systems are highly vulnerable to extreme warming events and expose the more general risk of relying on supposed sentinel species that are assumed to be very sensitive to climate change., Giant kelp is sometimes considered the ‘canary in the coal mine' of coastal ecosystems. However, Reed et al. demonstrate that kelp did not decline during recent ocean warming in California, questioning whether this species is an appropriate indicator for ecosystem responses to future climate change.

Demographic connectivity is vital to sustaining metapopulations yet often changes dramatically through time due to variation in the production and dispersal of offspring. However, the relative importance of variation in fecundity and dispersal in determining the connectivity and dynamics of metapopulations is poorly understood due to the paucity of comprehensive spatio-temporal data on these processes for most species. We quantified connectivity in metapopulations of a marine foundation species (giant kelpMacrocystis pyrifera) across 11 years and approximately 900 km of coastline by estimating population fecundity with satellite imagery and propagule dispersal using a high-resolution ocean circulation model. By varying the temporal complexity of different connectivity measures and comparing their ability to explain observed extinction–colonization dynamics, we discovered that fluctuations in population fecundity, rather than fluctuations in dispersal, are the dominant driver of variation in connectivity and contribute substantially to metapopulation recovery and persistence. Thus, for species with high variability in reproductive output and modest variability in dispersal (most plants, many animals), connectivity measures ignoring fluctuations in fecundity may overestimate connectivity and likelihoods of persistence, limiting their value for understanding and conserving metapopulations. However, we demonstrate how connectivity measures can be simplified while retaining utility, validating a practical solution for data-limited systems.

Kelp forests are among the world's most productive marine ecosystems, yet little is known about their biogeochemistry. This study presents a fourteen-month time series (July 2013–August 2014) of surface and benthic dissolved inorganic carbon and total alkalinity measurements, along with accompanying hydrographic measurements, from six locations within a central California kelp forest. We present ranges and patterns of variability in carbonate chemistry, including pH (7.70–8.33), pCO2 (172–952 µatm), and the aragonite saturation state, ΩAr (0.94–3.91). Surface-to-bottom gradients in CO2 system chemistry were as large as the spatial gradients throughout the bottom of the kelp forest. Dissolved inorganic carbon variability was the main driver of the observed CO2 system variability. The majority of spatial variability in the kelp forest can be explained by advection of cold, dense high CO2 waters into the bottom of the kelp forest, with deeper sites experiencing high CO2 conditions more frequently. Despite the strong imprint of advection on the biogeochemical variability of the kelp forest, surface waters were undersaturated with CO2 in the spring through fall, indicative of the strong role of photosynthesis on biogeochemical variability. We emphasize the importance of spatially distributed measurements for developing a process-based understanding of kelp forest ecosystem function in a changing climate.

Marine aquaculture is expanding into deeper offshore environments in response to growing consumer demand for seafood, improved technology, and limited potential to increase wild fisheries catches. Sustainable development of aquaculture will require quantification and minimization of its impacts on other ocean‐based activities and the environment through scientifically informed spatial planning. However, the scientific literature currently provides limited direct guidance for such planning. Here, we employ an ecological lens and synthesize a broad multidisciplinary literature to provide insight into the interactions between offshore aquaculture and the surrounding environment across a spectrum of spatial scales. While important information gaps remain, we find that there is sufficient research for informed decisions about the effects of aquaculture siting to achieve a sustainable offshore aquaculture industry that complements other uses of the marine environment.

Special economic zones (SEZs) have a long and complicated relationship with the United States. The lineage of the country runs back to proto-SEZs, created when Old World governments sold entrepreneurs charters to build for-profit colonies in the New World, such as Jamestown and New Amsterdam. In more recent times, though, the United States has lagged behind the rest of the globe in tapping the potential of SEZs, which have exploded in number, types, territory, and population. True, the US hosts a large and growing number of Foreign-Trade Zones (FTZs), but these do little more than exempt select companies from federal customs obligations. Elsewhere, SEZs have done much more to increase jurisdictional competition and improve citizens' lives. Consider the SEZs that spread from Hong Kong throughout China, lifting tens of millions of people out of poverty in the process, or the huge private developments now taking root in Africa, the Middle East, and India. This paper proposes that the United States combine the best of foreign and domestic policies to create a new generation of SEZs. These United States Special Economic Zones (USSEZs) would arise on federally owned property, such as lands managed by the Bureau of Land Management, and generate sorely needed public funds by selling territorial exemptions from select state and federal taxes, laws, and regulations. Through USSEZs, special jurisdictions might bring economic growth, human welfare, and individual freedom back to America.

Marine spatial planning (MSP) is increasingly utilized to sustainably manage ocean uses. Marine protected areas (MPAs), a form of spatial management in which parts of the ocean are regulated to fishing, are now a common tool in MSP for conserving marine biodiversity and managing fisheries. However, the use of MPAs in MSP often neglects – or simplifies – the redistribution of fishing and non-fishing activities inside and outside of MPAs following their implementation. This redistribution of effort can have important implications for effective MSP. Using long term (14 years) aerial surveys of boats at the California Channel Islands, we examined the spatial redistribution of fishing and non-fishing activities and their drivers following MPA establishment. Our data represent 6 years of information before the implementation of an MPA network and 8 years after implementation. Different types of boats responded in different ways to the closures, ranging from behaviors by commercial dive boats that support the hypothesis of fishing-the-line, to behaviors by urchin, sport fishing, and recreational boats that support the theory of ideal free distribution. Additionally, we found that boats engaged in recreational activities targeted areas that are sheltered from large waves and located near their home ports, while boats engaged in fishing activities also avoided high wave areas but were not constrained by the distance to their home ports. We did not observe the expected pattern of effort concentration near MPA borders for some boat types; this can be explained by the habitat preference of certain activities (for some activities, the desired habitat attributes are not inside the MPAs), species’ biology (species such as urchins where the MPA benefit would likely come from larval export rather than adult spillover), or policy-infraction avoidance. The diversity of boat responses reveals variance from the usual simplified assumption that all extractive boats respond similarly to MPA establishment. Our work is the first empirical study to analyze the response of both commercial and recreational boats to closure. Our results will inform MSP in better accounting for effort redistribution by ocean users in response to the implementation of MPAs and other closures. This article is protected by copyright. All rights reserved.

Libertarians do not fit into the left-right spectrum very comfortably; by their own account, they transcend it. This brief paper, written for a Chapman Law Review symposium on libertarian legal theory, argues that libertarians should likewise transcend the dichotomy currently dividing constitutional theory. The Left tends to regard the Constitution as adaptable to current needs and defined by judicial authority; the Right tends to search the historical record for the Constitution’s original meaning. Each of those conventional approaches has its own virtues and vices. Combining the best of both — the responsiveness of living constitutionalism and the textual fidelity of originalism — generates a distinctly libertarian theory. This theory maximizes the consent of the governed and, thus, the justifiability of constitutional authority.