Climate change (CC) represents an increasing threat to mangroves worldwide and can amplify impacts caused by local anthropogenic activities. The direct effects of CC on mangrove forests have been extensively discussed, but indirect impacts such as the alteration of ecological processes driven by specific functional groups of the biota are poorly investigated. Ecological roles of key functional groups (FGs) in mangroves from the Atlantic–Caribbean–East Pacific (ACEP) and Indo-West Pacific (IWP) regions are reviewed, and impacts from CC mediated by these FGs are explored. Disruption by CC of ecological processes, driven by key FGs, can reinforce direct effects and amplify the loss of ecological functionality and further degradation of mangrove forests. Biogeochemistry mediator microbiotas of the soil, bioturbators, especially semiterrestrial crabs (Ocypodoids and Grapsoids) and herbivores (crustaceans and Insects), would be the most affected FG in both regions. Effects of climate change can vary regionally in the function of the combination of direct and indirect drivers, further eroding biodiversity and mangrove resilience, and impairing the predictability of ecosystem behaviour. This means that public policies to manage and conserve mangroves, as well as rehabilitation/restoration programs, should take into consideration the pressures of CC in specific regions and the response of key FGs to these pressures.

Substantial amounts of dead wood in the intertidal zone of mature mangrove forests are tunnelled by teredinid bivalves. When the tunnels are exposed, animals are able to use tunnels as refuges. In this study, the effect of teredinid tunnelling upon mangrove forest faunal diversity was investigated. Mangrove forests exposed to long emersion times had fewer teredinid tunnels in wood and wood not containing teredinid tunnels had very few species and abundance of animals. However, with a greater cross-sectional percentage surface area of teredinid tunnels, the numbers of species and abundance of animals was significantly higher. Temperatures within teredinid-attacked wood were significantly cooler compared with air temperatures, and animal abundance was greater in wood with cooler temperatures. Animals inside the tunnels within the wood may avoid desiccation by escaping the higher temperatures. Animals co-existing in teredinid tunnelled wood ranged from animals found in terrestrial ecosystems including centipedes, crickets and spiders, and animals found in subtidal marine ecosystems such as fish, octopods and polychaetes. There was also evidence of breeding within teredinid-attacked wood, as many juvenile individuals were found, and they may also benefit from the cooler wood temperatures. Teredinid tunnelled wood is a key low-tide refuge for cryptic animals, which would otherwise be exposed to fishes and birds, and higher external temperatures. This study provides evidence that teredinids are ecosystem engineers and also provides an example of a mechanism whereby mangrove forests support intertidal biodiversity and nurseries through the wood-boring activity of teredinids.

There has been limited research on the breakdown, recycling, and flux of carbon from large woody detritus (LWD) in mangrove forests. The breakdown of LWD is caused by guilds of terrestrial and marine biodegrading organisms that degrade wood at a range of rates and efficiencies. Spatial variations in environmental factors within mangroves affect the distribution and community of biodegrading organisms, which, in turn, impacts carbon flow and sequestration. We reveal the role of biodegrading organisms in LWD breakdown and the environmental factors that influence the distribution of biodegrading guilds within a mangrove forest in South East Sulawesi that supports a diversity of mangrove species typical of Indonesian mangrove forests, which constitute 20% of Global mangrove cover. Within the high intertidal regions, terrestrial biodegradation processes dominated upon LWD. After 12 months exposure on the forest floor, experimental wooden panels in these areas remained unchanged in mass and condition. In the low intertidal region, marine wood-boring animals belonging to the family Teredinidae were the dominant biodegraders of LWD, and their activity reduces LWD volume and speeds up the loss of LWD volume. More than 50% of the experimental wooden panels’ weight in these areas was lost after 12 months exposure on the forest floor. Although different biodegrading guilds occupy the same LWD niche, their distribution throughout the mangrove forest is influenced by inundation time. The change of biodegrading guilds within LWD between the terrestrial and the marine organisms was distinct, creating a biodegradation boundary in a distance as narrow as 1 m on the mangrove forest floor. These results are important, as rising sea levels have crucial implications for biodegrading guilds. A full understanding of factors affecting the biodegradation processes of LWD in mangrove forests is critical to accurately assess mangrove carbon stores and the fate of mangrove derived carbon.

Hurricane incidents have become increasingly frequent along the coastal United States and have had a negative impact on the mangrove forests and their ecosystem services across the southeastern region. Mangroves play a key role in providing coastal protection during hurricanes by attenuating storm surges and reducing erosion. However, their resilience is being increasingly compromised due to climate change through sea level rises and the greater intensity of storms. This article examines the role of remote sensing tools in studying the impacts of hurricanes on mangrove forests in the coastal United States. Our results show that various remote sensing tools including satellite imagery, Light detection and ranging (LiDAR) and unmanned aerial vehicles (UAVs) have been used to detect mangrove damage, monitor their recovery and analyze their 3D structural changes. Landsat 8 OLI (14%) has been particularly useful in long-term assessments, followed by Landsat 5 TM (9%) and NASA G-LiHT LiDAR (8%). Random forest (24%) and linear regression (24%) models were the most common modeling techniques, with the former being the most frequently used method for classifying satellite images. Some studies have shown significant mangrove canopy loss after major hurricanes, and damage was seen to vary spatially based on factors such as proximity to oceans, elevation and canopy structure, with taller mangroves typically experiencing greater damage. Recovery rates after hurricane-induced damage also vary, as some areas were seen to show rapid regrowth within months while others remained impacted after many years. The current challenges include capturing fine-scale changes owing to the dearth of remote sensing data with high temporal and spatial resolution. This review provides insights into the current remote sensing applications used in hurricane-prone mangrove habitats and is intended to guide future research directions, inform coastal management strategies and support conservation efforts.

Populations of the European flat oysterOstrea edulishave experienced catastrophic declines across Europe and subsequent spread of the non-native speciesCrepidula fornicatahas led to its occurrence in exceptionally high densities in some areas previously dominated byO. edulis. Spatial and temporal concurrence ofC. fornicatalarvae within the zooplankton community occurs throughout theO. edulisspawning season. AC. fornicatalarval peak density of 374.7 +/- 96.5 larvae/ml (mean +/- SD) was observed in Langston Harbour sympatrically withO. edulisdensity of 45.7 +/- 20.1 larvae/ml in early August. Overall oyster larvae contribution to the zooplankton community was higher in Portsmouth Harbour (12%) thanC. fornicatacontribution (9.6%), whilst the opposite occurred in Langstone (oysters, 11.7%;C. fornicata, 12%). Larval abundance is not reflected in recruitment on the seabed, owing to the conspecific substrate preference ofO. edulis. Settlement ofO. edulisspat was significantly greater on settlement discs covered with recently deceased oyster shells; 6.7 +/- 1.2 (mean +/- SE) spat/disc vs old smooth oyster shells, 2.7 +/- 1.3,C. fornicatashell 1.7 +/- 0.3, cemented discs 2 +/- 1 or the plastic control disc 0.7 +/- 0.7. Settlement substrate type matters in the presence of high benthic and larval densities ofC. fornicata. The Solent has become a substrate-limited system forO. edulis; substrate management or reef deployment is required to restore a self-recruiting population. Finally, althoughC. fornicatamay provide functional equivalence in terms of filtering services, it supports a significantly different and less biodiverse faunal community from that ofO. edulis. ThereforeC. fornicatadoes not provide equivalence as an ecosystem engineer and mechanisms of ecological phase shift are occurring within areas dominated by this invasive species.