The capability of animals to emit light, called bioluminescence, is considered to be a major factor in ecological interactions. Because it occurs across diverse taxa, measurements of bioluminescence can be powerful to detect and quantify organisms in the ocean. In this study, 17 years of video observations were recorded by remotely operated vehicles during surveys off the California Coast, from the surface down to 3,900 m depth. More than 350,000 observations are classified for their bioluminescence capability based on literature descriptions. The organisms represented 553 phylogenetic concepts (species, genera or families, at the most precise taxonomic level defined from the images), distributed within 13 broader taxonomic categories. The importance of bioluminescent marine taxa is highlighted in the water column, as we showed that 76% of the observed individuals have bioluminescence capability. More than 97% of Cnidarians were bioluminescent, and 9 of the 13 taxonomic categories were found to be bioluminescent dominant. The percentage of bioluminescent animals is remarkably uniform over depth. Moreover, the proportion of bioluminescent and non-bioluminescent animals within taxonomic groups changes with depth for Ctenophora, Scyphozoa, Chaetognatha, and Crustacea. Given these results, bioluminescence has to be considered an important ecological trait from the surface to the deep-sea.
Over the last 30 years, a range of different livelihoods have been provided and implemented in fishing and coastal communities in the Philippine with mixed success and sustainability by the fisher and household. This paper reports on an analysis of livelihood projects for fishing communities and households implemented in the Philippines and the identification of lessons learned and factors which can lead to an improved success and sustainability rate for livelihood projects and programs. The analysis identified primary factors that are critical to improving the success and sustainability rate of livelihood interventions.
One way that illegal, unreported, and unregulated (IUU) fish catch is laundered into the seafood market is through transshipments at-sea. This practice, which often occurs on the high seas (the areas of ocean beyond national jurisdiction), allows vessels fishing illegally to evade most monitoring and enforcement measures, offload their cargo, and resume fishing without returning to port. At the same time, transshipment at-sea can facilitate trafficking and exploitation of workers who are trapped and abused on fishing vessels. This study gives an overview of high seas transshipment as well as evaluates transshipment at-sea regulations across 17 Regional Fisheries Management Organizations (RFMOs), which are responsible for regulating fisheries on the high seas. Transshipment at-sea regulations have become increasingly strict in most RFMOs since the late 1990s. However, only five RFMOs have mandated a partial ban, and only a single RFMO, the South East Atlantic Fisheries Organization (SEAFO), has mandated a total ban on transshipment at-sea. A total ban on transshipment at-sea across all RFMOs would support the ability of oversight and enforcement agencies to detect and prevent IUU fishing and also likely reduce human trafficking and forced labor on the high seas.
The distribution, abundance, and species assemblage of top predators - seabirds and cetaceans - can be correlated to water masses as defined by hydrological parameters. Compared to other oceans, information about the structuring effects of water masses on top predators in the Atlantic Ocean is limited. The present study aims 1) to provide baseline distributional data of top predators for future comparisons, for instance in the course of climate change, and 2) to test how water masses and seasons affect distributional patterns of seabirds and cetaceans in the temperate and tropical Atlantic. During four trans-equatorial expeditions of the RV Polarstern between 2011 and 2014, at-sea observation data of seabirds, cetaceans and other megafauna were collected. Counts of top predators were generally low in the surveyed regions. Statistical analyses for the eight most abundant seabird species and the pooled number of cetaceans revealed water masses and seasons to account for differences in counts and thus also distribution. In most cases, borders between water masses were not very distinct due to gradual changes in surface water properties. Thus, top predator counts were correlated to water masses but, in contrast to polar waters, not strongly linked to borders between water masses. Additional factors, e.g. distance to locally productive areas (upwelling), competition effects, and seabird associations to prey-accumulating subsurface predators may be similarly important in shaping distributional patterns of top predators in the tropical and temperate Atlantic, but could not be specifically tested for here.
Coastal nursery habitats are essential for the renewal of adult fish populations. We quantified the availability of a coastal nursery habitat (shallow heterogeneous rocky bottoms) and the spatial variability of its juvenile fish populations along 250 km of the Catalan coastline (France and Spain). Nurseries were present in 27% of the coastline, but only 2% of them benefited from strict protection status. For nine taxa characteristic of this habitat, total juvenile densities varied significantly between nursery sites along the coastline, with the highest densities being found on the northern sites. Recruitment level (i.e. a proxy of nursery value) was not explained by protection level, but it was moderately and positively correlated with an anthropization index. Patterns of spatial variations were taxa-specific. Exceptional observations of four juveniles of the protected grouper Epinephelus marginatus were recorded. Our data on habitat availability and recruitment levels provides important informations which help to focus MPA management efforts.
Changes imposed to nature by human activities and related impacts on all environmental matrices have become a critical issue. Gradually, humans began to perceive and face the magnitude of the impact of human economy on natural ecosystems and the implications for human well-being. From this perception, the concepts of natural capital and ecosystem services arose, highlighting the relationships between natural and human economy while boosting environmental conservation and management. In this framework, the definition and application of metrics and models capable of accounting for natural capital value are much needed. This is even more important when a protection regime is established (such as in the case of marine protected areas) to evaluate the efficacy of undertaken conservation measures. In this study, a biophysical and trophodynamic environmental accounting model was developed to assess the value of natural capital in marine protected areas. The model of natural capital assessment is articulated in three main steps: 1) trophodynamic analysis, providing an estimate of the primary productivity used to support the benthic trophic web within the study area, 2) biophysical accounting, providing an estimate of the biophysical value of natural capital by means of emergy accounting, and 3) monetary conversion, expressing the biophysical value of natural capital into monetary units. This conversion does not change the biophysical feature of the assessment, but instead it has the merit of allowing an easier understanding and effective communication of the ecological value of natural capital in socio-economic contexts.
This paper presents GIS time-series land-use analysis of satellite images to quantify the recovery of rice cultivation and aquaculture following the 2004 Indian Ocean tsunami in coastal communities in Aceh, Indonesia. We supplement this with qualitative data to illustrate the post-disaster challenges faced by residents, and the extent to which coastal communities have adapted to post-tsunami realities. Our analysis shows that the rehabilitation of rice cultivation and aquaculture in areas inundated by the tsunami has been limited by extensive degradation of land, diversion of labor by tsunami mortality and transition to alternative livelihoods, and re-purposing of rice fields for residential use during the reconstruction phase. This is especially prominent in areas where subsistence activities are not the primary source of livelihood. The Aceh case study shows that social, economic, and environmental factors can be stronger determinants of how coastal livelihoods rebound and change following destructive inundation events than livelihood rehabilitation aid. Additionally, our case study suggests the human impact of coastal hazards can be felt outside the physical extent of inundation.
Research and monitoring activities over the 28 years since the T/V Exxon Valdez ran aground and spilled oil into Prince William Sound, Alaska have led to an improved understanding of how wildlife populations were damaged, as well as the mechanisms and timelines of recovery. A key finding was that for some species, such as harlequin ducks and sea otters, chronic oil spill effects persisted for at least two decades and were a larger influence on population dynamics over the long term than acute effects of the spill. These data also offer insights into population variation resulting from factors other than the oil spill. For example, while many seabirds experienced direct and indirect effects of the spill, population trajectories of some piscivorous birds, including pigeon guillemots and marbled murrelets, were linked to long-term environmental changes independent of spill effects. Another species, killer whales, suffered population declines due to acute spill effects that have not been resolved despite lack of chronic direct effects, representing a novel pathway of long-term injury. The observed variation in mechanisms and timelines of recovery is linked to species specific life history and natural history traits, and thus may be useful for predicting population recovery for other species following other spills.
Species distribution modelling can be applied to identify potentially suitable habitat for species with largely unknown distributions, such as many deep-water corals. Important variables influencing species occurrence in the deep sea, e.g. substrate composition, are often not included in these modelling approaches because high-resolution data are unavailable. We investigated the relationship between substrate composition and the occurrence of the two deep-water octocoral species Primnoa resedaeformis and Paragorgia arborea, which require hard substrate for attachment. On a scale of 10 s of metres, we analysed images of the seafloor taken at two locations inside the Northeast Channel Coral Conservation Area in the Northwest Atlantic. We interpolated substrate composition over the sampling areas and determined the contribution of substrate classes, depth and slope to describe habitat suitability using maximum entropy modelling (Maxent). Substrate composition was similar at both sites - dominated by pebbles in a matrix of sand (>80%) with low percentages of suitable substrate for coral occurrence. Coral abundance was low at site 1 (0.9 colonies of P. resedaeformis per 100 m2) and high at site 2 (63 colonies of P. resedaeformis per 100 m2) indicating that substrate alone is not sufficient to explain varying patterns in coral occurrence. Spatial interpolations of substrate classes revealed the difficulty to accurately resolve sparsely distributed boulders (3 – 5% of substrate). Boulders were by far the most important variable in the habitat suitability model (HSM) for P. resedaeformis at site 1, indicating the fundamental influence of a substrate class that is the least abundant. At site 2, HSMs identified cobbles and sand/pebble as the most important variables for habitat suitability. However, substrate classes were correlated making it difficult to determine the influence of individual variables. To provide accurate information on habitat suitability for the two coral species, substrate composition needs to be quantified so that small fractions (<20% contribution of certain substrate class) of suitable substrate are resolved. While the collection and analysis of high-resolution data is costly and spatially limited, the required resolution is unlikely to be achieved in coarse-scale interpolations of substrate data.
With increasing demand for mineral resources, extraction of polymetallic sulphides at hydrothermal vents, cobalt-rich ferromanganese crusts at seamounts, and polymetallic nodules on abyssal plains may be imminent. Here, we shortly introduce ecosystem characteristics of mining areas, report on recent mining developments, and identify potential stress and disturbances created by mining. We analyze species’ potential resistance to future mining and perform meta-analyses on population density and diversity recovery after disturbances most similar to mining: volcanic eruptions at vents, fisheries on seamounts, and experiments that mimic nodule mining on abyssal plains. We report wide variation in recovery rates among taxa, size, and mobility of fauna. While densities and diversities of some taxa can recover to or even exceed pre-disturbance levels, community composition remains affected after decades. The loss of hard substrata or alteration of substrata composition may cause substantial community shifts that persist over geological timescales at mined sites.