The social and economic benefits of the coastal zone make it one of the most treasured environments on our planet. Yet it is vulnerable to increasing anthropogenic pressure and climate change. Coastal management aims to mitigate these pressures while augmenting the socio-economic benefits the coastal region has to offer. However, coastal management is challenged by inadequate sampling of key environmental indicators, partly due to issues relating to cost of data collection. Here, we investigate the use of recreational surfers as platforms to improve sampling coverage of environmental indicators in the coastal zone. We equipped a recreational surfer, based in the south west United Kingdom (UK), with a temperature sensor and Global Positioning System (GPS) device that they used when surfing for a period of one year (85 surfing sessions). The temperature sensor was used to derive estimates of sea-surface temperature (SST), an important environmental indicator, and the GPS device used to provide sample location and to extract information on surfer performance. SST data acquired by the surfer were compared with data from an oceanographic station in the south west UK and with satellite observations. Our results demonstrate: (i) high-quality SST data can be acquired by surfers using low cost sensors; and (ii) GPS data can provide information on surfing performance that may help motivate data collection by surfers. Using recent estimates of the UK surfing population, and frequency of surfer participation, we speculate around 40 million measurements on environmental indicators per year could be acquired at the UK coastline by surfers. This quantity of data is likely to enhance coastal monitoring and aid UK coastal management. Considering surfing is a world-wide sport, our results have global implications and the approach could be expanded to other popular marine recreational activities for coastal monitoring of environmental indicators.
Seaweeds that lack carbon-concentrating mechanisms are potentially inorganic carbon-limited under current air equilibrium conditions. To estimate effects of increased atmospheric carbon dioxide concentration and ocean acidification on photosynthetic rates, we modeled rates of photosynthesis in response to pCO2, temperature, and their interaction under limiting and saturating photon flux densities. We synthesized the available data for photosynthetic responses of red seaweeds lacking carbon-concentrating mechanisms to light and temperature. The model was parameterized with published data and known carbonate system dynamics. The model predicts that direction and magnitude of response to pCO2 and temperature, depend on photon flux density. At sub-saturating light intensities, photosynthetic rates are predicted to be low and respond positively to increasing pCO2, and negatively to increasing temperature. Consequently, pCO2 and temperature are predicted to interact antagonistically to influence photosynthetic rates at low PFD. The model predicts that pCO2 will have a much larger effect than temperature at sub-saturating light intensities. However, photosynthetic rates under low light will not increase proportionately as pCO2 in seawater continues to rise. In the range of light saturation (Ik), both CO2 and temperature have positive effects on photosynthetic rate and correspondingly strong predicted synergistic effects. At saturating light intensities, the response of photosynthetic rates to increasing pCO2 approaches linearity, but the model also predicts increased importance of thermal over pCO2 effects, with effects acting additively. Increasing boundary layer thickness decreased the effect of added pCO2 and, for very thick boundary layers, overwhelmed the effect of temperature on photosynthetic rates. The maximum photosynthetic rates of strictly CO2-using algae are low, so even large percentage increases in rates with climate change will not contribute much to changing primary production in the habitats where they commonly live.
With a rapidly changing climate, there is an increasing need to predict how species will respond to changes in the physical environment. One approach is to use historic data to estimate the past influence of environmental variation on important demographic parameters and then use these relationships to project the abundance of a population or species under future climate scenarios. However, as novel climate conditions emerge, novel species responses may also appear. In some systems, environmental conditions beyond the range of those observed during the course of most long-term ecological studies are already evident. Yet little attention has been given to how these novel conditions may be influencing previously established environment–species relationships. Here, we model the relationships between ocean conditions and the demography of a long-lived seabird, Brandt’s cormorant (Phalacrocorax penicillatusI), in central California and show that these relationships have changed in recent years. Beginning in 2007/2008, the response of Brandt’s cormorant, an upper trophic level predator, to ocean conditions shifted, resulting in lower than predicted survival and breeding probability. Survival was generally less variable than breeding probability and was initially best predicted by the basin-scale forcing of the El Niño Southern Oscillation rather than local ocean conditions. The shifting response of Brandt’s cormorant to ocean conditions may be just a proximate indication of altered dynamics in the food web and that important forage fish are not responding to the physical ocean environment as expected. These changing relationships have important implications for our ability to project the effects of future climate change for species and communities.
Ecosystem degradation has become common throughout the world. On coral reefs, macroalgal outbreaks are one of the most widely documented signs of degradation. This study simulated local-scale degradation on a healthy coral reef to determine how resident taxa, with the potential to reverse algal outbreaks, respond. We utilized a combination of acoustic and video monitoring to quantify changes in the movements and densities, respectively, of coral reef herbivores following a simulated algal outbreak. We found an unprecedented accumulation of functionally important herbivorous taxa in response to algal increases. Herbivore densities increased by 267% where algae were present. The increase in herbivore densities was driven primarily by an accumulation of the browsing taxa Naso unicornis and Kyphosus vaigiensis, two species which are known to be important in removing macroalgae and which may be capable of reversing algal outbreaks. However, resident individuals at the site of algal increase exhibited no change in their movements. Instead, analysis of the size classes of the responding individuals indicates that large functionally-important non-resident individuals changed their movement patterns to move in and feed on the algae. This suggests that local-scale reef processes may not be sufficient to mitigate the effects of local degradation and highlights the importance of mobile links and cross-scale interactions.
Globally the majority of commercial fisheries have experienced dramatic declines in stock and catch. Likewise, projections for many subsistence fisheries in the tropics indicate a dramatic decline is looming in the coming decades. In the Pacific Islands coastal fisheries provide basic subsistence needs for millions of people. A decline in fish catch would therefore have profound impacts on the health and livelihoods of these coastal communities. Given the decrease in local catch rates reported for many coastal communities in the Pacific, it is important to understand if fishers have responded to ecological change (either by expanding their fishing range and/or increasing their fishing effort), and if so, to evaluate the costs or benefits of these responses. We compare data from fish catches in 1995 and 2011 from a rural coastal community in Solomon Islands to examine the potentially changing coastal reef fishery at these time points. In particular we found changes in preferred fishing locations, fishing methodology and catch composition between these data sets. The results indicate that despite changes in catch rates (catch per unit effort) between data collected in 2011 and 16 years previously, the study community was able to increase gross catches through visiting fishing sites further away, diversifying fishing methods and targeting pelagic species through trolling. Such insight into local-scale responses to changing resources and/or fisheries development will help scientists and policy makers throughout the Pacific region in managing the region’s fisheries in the future.
lobal climate change and other anthropogenic stressors have heightened the need to rapidly characterize ecological changes in marine benthic communities across large scales. Digital photography enables rapid collection of survey images to meet this need, but the subsequent image annotation is typically a time consuming, manual task. We investigated the feasibility of using automated point-annotation to expedite cover estimation of the 17 dominant benthic categories from survey-images captured at four Pacific coral reefs. Inter- and intra- annotator variability among six human experts was quantified and compared to semi- and fully- automated annotation methods, which are made available at coralnet.ucsd.edu. Our results indicate high expert agreement for identification of coral genera, but lower agreement for algal functional groups, in particular between turf algae and crustose coralline algae. This indicates the need for unequivocal definitions of algal groups, careful training of multiple annotators, and enhanced imaging technology. Semi-automated annotation, where 50% of the annotation decisions were performed automatically, yielded cover estimate errors comparable to those of the human experts. Furthermore, fully-automated annotation yielded rapid, unbiased cover estimates but with increased variance. These results show that automated annotation can increase spatial coverage and decrease time and financial outlay for image-based reef surveys.
Mesophotic hard corals (MHC) are increasingly threatened by a growing number of anthropogenic stressors, including impacts from fishing, land-based sources of pollution, and ocean acidification. However, little is known about their geographic distributions (particularly around the Pacific islands) because it is logistically challenging and expensive to gather data in the 30 to 150 meter depth range where these organisms typically live. The goal of this study was to begin to fill this knowledge gap by modelling and predicting the spatial distribution of three genera of mesophotic hard corals offshore of Maui in the Main Hawaiian Islands. Maximum Entropy modeling software was used to create separate maps of predicted probability of occurrence and uncertainty for: (1) Leptoseris, (2) Montipora, and (3) Porites. Genera prevalence was derived from the in situ presence/absence data, and used to convert relative habitat suitability to probability of occurrence values. Approximately 1,300 georeferenced records of the occurrence of MHC, and 34 environmental predictors were used to train the model ensembles. Receiver Operating Characteristic (ROC) Area Under the Curve (AUC) values were between 0.89 and 0.97, indicating excellent overall model performance. Mean uncertainty and mean absolute error for the spatial predictions ranged from 0.006% to 0.05% and 3.73% to 17.6%, respectively. Depth, distance from shore, euphotic depth (mean and standard deviation) and sea surface temperature (mean and standard deviation) were identified as the six most influential predictor variables for partitioning habitats among the three genera. MHC were concentrated between Hanaka‘ō‘ō and Papawai Points offshore of western Maui most likely because this area hosts warmer, clearer and calmer water conditions almost year round. While these predictions helped to fill some knowledge gaps offshore of Maui, many information gaps remain in the Hawaiian Archipelago and Pacific Islands. This approach may be used to identify other potentially suitable areas for MHCs, helping scientists and resource managers prioritize sites, and focus their limited resources on areas that may be of higher scientific or conservation value.