It is fundamentally important for many animal ecologists to quantify the costs of animal activities, although it is not straightforward to do so. The recording of triaxial acceleration by animal‐attached devices has been proposed as a way forward for this, with the specific suggestion that dynamic body acceleration (DBA) be used as a proxy for movement‐based power. Dynamic body acceleration has now been validated frequently, both in the laboratory and in the field, although the literature still shows that some aspects of DBA theory and practice are misunderstood. Here, we examine the theory behind DBA and employ modelling approaches to assess factors that affect the link between DBA and energy expenditure, from the deployment of the tag, through to the calibration of DBA with energy use in laboratory and field settings. Using data from a range of species and movement modes, we illustrate that vectorial and additive DBA metrics are proportional to each other. Either can be used as a proxy for energy and summed to estimate total energy expended over a given period, or divided by time to give a proxy for movement‐related metabolic power. Nonetheless, we highlight how the ability of DBA to predict metabolic rate declines as the contribution of non‐movement‐related factors, such as heat production, increases. Overall, DBA seems to be a substantive proxy for movement‐based power but consideration of other movement‐related metrics, such as the static body acceleration and the rate of change of body pitch and roll, may enable researchers to refine movement‐based metabolic costs, particularly in animals where movement is not characterized by marked changes in body acceleration.

Exotic species are a growing global ecological threat; however, their overall effects are insufficiently understood. While some exotic species are implicated in many species extinctions, others can provide benefits to the recipient communities. Here, we performed a meta-analysis to quantify and synthesize the ecological effects of 76 exotic marine species (about 6% of the listed exotics) on ten variables in marine communities. These species caused an overall significant, but modest in magnitude (as indicated by a mean effect size of g < 0.2), decrease in ecological variables. Marine primary producers and predators were the most disruptive trophic groups of the exotic species. Approximately 10% (that is, 2 out of 19) of the exotic species assessed in at least three independent studies had significant impacts on native species. Separating the innocuous from the disruptive exotic species provides a basis for triage efforts to control the marine exotic species that have the most impact, thereby helping to meet Aichi Biodiversity Target 9 of the Convention on Biological Diversity.

15The role of macroalgae in Blue Carbon assessments has been controversial, partially due to 16 uncertainties on the fate of exported macroalgae. Available evidence suggests that macroalgae is 17 exported to reach the open ocean and the deep-sea. Nevertheless, this evidence lack of systematic 18 assessment. Here, we provide robust evidence of macroalgal export beyond coastal habitats. We 19 used metagenomes and metabarcodes from the global expeditions Tara Oceans and Malaspina 20 2010 Circumnavigation. We discovered macroalgae worldwide at up to 5,000 km from coastal 21 areas. We found 24 orders, most of them belong to Rhodophyta. Diversity of macroalgae was 22 similar across oceanic regions, although the assemblage composition differed. The South 45 macroalgae are few 10 . This evidence imbalance could be related to lineage-specific features of 46 the macroalgae cell wall composition and differences in cell-degradation rates 11 . Furthermore, 47 most calculations of macroalgal primary production suggest that macroalgal carbon is exported 48 as dissolved and particulate organic carbon (DOC and POC) 12,13 , which are not visually 49detectable. An inclusive method, such as the identification of macroalgal environmental DNA 50 (eDNA), could provide evidence of macroalgal carbon export in the ocean, and may allow the 51 required systematic and consistent assessments. eDNA is the DNA left behind by organisms in 52 the surrounding environment including degraded cell tissues, gametes, animal feces, etc. As 53 DNA comprises approximately 3% of cellular organic carbon 14 , the presence of macroalgal DNA 54 in waters beyond macroalgal habitats is both an indicator of the presence of the species and 55 evidence (not necessarily quantitative) of the export of macroalgal carbon. 56Here, we examined the presence and relative abundance of Rhodophyta, Phaeophyta, and 57Chlorophyta macroalgal eDNA sequences in the ocean. The sequences were derived from 58 hundreds of metagenomes generated by two global expeditions: Tara Oceans 15 and Malaspina 59 2010 Circumnavigation 16 . These expeditions surveyed the global ocean from surface to 4,000 m 60 depth, and sequenced the particulate material present in environmental water samples 17,18 (see 61 Methods). Although the expeditions primarily assessed the microbial and planktonic diversity, 62 they also generated a global DNA resource that allows identification of multicellular eukaryotes. 63We exploited the potential of this eukaryotic eDNA resource to explore the presence of 64 macroalgae in the global ocean. This holistic approach has not been attempted before, but is 65 semi-quantitative and consistent for evaluating the hypothesis that macroalgal material is broadly 66 exported across the global ocean. 67We identified macroalgae using two global ocean datasets. The first one included 163 68 metabarcodes of amplicon 18S rDNA from Tara Oceans 19 . The second one included 417 69 metagenomes pooled from the Tara Oceans 20 and Malaspina 21 expeditions (see Methods). We 70 used two differe...

The global lockdown to mitigate COVID-19 pandemic health risks has altered human interactions with nature. Here, we report immediate impacts of changes in human activities on wildlife and environmental threats during the early lockdown months of 2020, based on 877 qualitative reports and 332 quantitative assessments from different studies. Hundreds of reports of unusual species observations from around the world suggest that animals quickly responded to the reductions in human presence. However, negative effects of lockdown on conservation also emerged, as confinement resulted in some park officials being unable to perform conservation, restoration and enforcement tasks, resulting in local increases in illegal activities such as hunting. Overall, there is a complex mixture of positive and negative effects of the pandemic lockdown on nature, all of which have the potential to lead to cascading responses which in turn impact wildlife and nature conservation. While the net effect of the lockdown will need to be assessed over years as data becomes available and persistent effects emerge, immediate responses were detected across the world. Thus, initial qualitative and quantitative data arising from this serendipitous global quasi-experimental perturbation highlights the dual role that humans play in threatening and protecting species and ecosystems. Pathways to favorably tilt this delicate balance include reducing impacts and increasing conservation effectiveness.

Calcium carbonates (CaCO 3 ) often accumulate in mangrove and seagrass sediments. As CaCO 3 production emits CO 2 , there is concern that this may partially offset the role of Blue Carbon ecosystems as CO 2 sinks through the burial of organic carbon (C org ). A global collection of data on inorganic carbon burial rates (C inorg , 12% of CaCO 3 mass) revealed global rates of 0.8 TgC inorg yr −1 and 15–62 TgC inorg yr −1 in mangrove and seagrass ecosystems, respectively. In seagrass, CaCO 3 burial may correspond to an offset of 30% of the net CO 2 sequestration. However, a mass balance assessment highlights that the C inorg burial is mainly supported by inputs from adjacent ecosystems rather than by local calcification, and that Blue Carbon ecosystems are sites of net CaCO 3 dissolution. Hence, CaCO 3 burial in Blue Carbon ecosystems contribute to seabed elevation and therefore buffers sea-level rise, without undermining their role as CO 2 sinks.