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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. [ABSTRACT FROM AUTHOR]

ABSTRACT The Pacific oyster Crassostrea gigas (Thunberg, 1793) is an important part of the aquaculture industry in Europe; however, since 2008, oyster mortality events (>20%) have become a regular summer [...]

Coastal ecosystems are particularly vulnerable to alien invasions. Regular, standardized, targeted monitoring of coastal areas helps to detect the arrival of non-native species early, identify sites most vulnerable to invasion, and assess potential for further spread. This study quantified the spread and changes in distribution of non-native oyster, Crassostrea gigas , populations around the coast of Ireland. In total 37 sites were surveyed, in areas which either currently or previously harboured cultivated C. gigas , for the presence and abundance of 'wild' C. gigas. Wild populations were identified at 20 sites and at four additional sites C. gigas was observed as recently discarded from aquaculture activity. Five of the invaded sites were identified as being highly suitable for a population expansion based on their current population status. Importantly, we also identified individuals of C. gigas and native European oysters, Ostrea edulis , co-occurring within the same shore at five sites. This is the first record to our knowledge of such co-occurrence within Europe. This evidence of co-existing oyster species raises concerns regarding the potential impact of C. gigas on recovering O. edulis populations. In Ireland, however, C. gigas does not typically spread extensively from introduction points, and although self-containing populations exist, they are currently sustained at a much lower density than those observed in other regions such as the Wadden Sea or French Atlantic coasts. We suggest, therefore, that to protect native oyster populations, C. gigas should be eradicated where co-occurring with O. edulis and recommend continuous monitoring of invaded sites. [ABSTRACT FROM AUTHOR]

Abstract: The European native oyster, Ostrea edulis, has been in severe decline since the early 1900s across Europe with many fisheries now declared commercially extinct. In light of this broad scale population decline, the UK has listed O. edulis as a threatened species, requiring conservation action under the Biodiversity Action Plan (BAP). In addition to this designation, in Scotland O. edulis beds is a search feature (SF) and a priority marine feature (PMF) for MPA site selection. These sites are also listed as a feature of conservation importance and included on the OSPAR list of threatened/declining species and habitats. Recent studies have identified O. edulis populations with heavily male‐skewed sex ratios, which may have contributed to fisheries decline due to reduced levels of fertilization. This species is a protandrous alternating hermaphrodite and individuals may change sex in response to local conditions. This study aimed to assess how sex ratios vary temporally and if this is correlated with temperature, by studying two exploited populations in Loch Ryan, Scotland and Chichester Harbour, England. This study suggests that the proportion of male phase oysters is positively correlated with water temperature and that the study population in cooler waters had a more balanced sex ratio overall (the Loch Ryan population was significantly similar to 1:1 for 10 of 13 months, whereas in Chichester only 1 of the 7 months was significantly similar). This study provides evidence to suggest that a critical temperature threshold for sex determination exists in O. edulis and for the Loch Ryan population we suggest that this is 16.5°C. However, further work is required to assess how this threshold may change between sites and how future climate change scenarios might affect the sex ratio of native oyster populations. [ABSTRACT FROM AUTHOR]