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The urbanisation of coastal areas increases both Artificial Light At Night (ALAN) and man-made structures. ALAN poses significant challenges to coastal ecosystems by altering species physiology and behaviour. Its effects might differ considerably between man-made and natural habitats due to varying habitat complexity and biological assemblages. This systematic review assesses the current knowledge and gaps regarding the ecological effects of the interaction between ALAN and different coastal hard-bottom habitats on intertidal and shallow-subtidal reefs. Of the 57 retrieved studies, most are laboratory experiments (40) on the physiology and behaviour of rocky shore (24) or coral reef (16) species. Field studies were conducted in artificial (6) and natural habitats (9), with only 2 comparing the two habitat types. These studies illustrate ALAN impacts on various species, with potential cascading effects on entire communities through the alteration of competitive and consumer-resource interactions. Different habitat structures may interact with ALAN by generating highly heterogeneous lightscapes (e.g., natural rocky shores), regular light-shadow mosaics (e.g., breakwaters), vast homogeneously lit areas (e.g., seawalls), or constantly shaded areas (e.g., pontoons). This creates a variable mismatch in natural light conditions, which may be further influenced by the introduction of additional light sources (e.g., moored boats with underwater coloured lights). As coastal development and light pollution continue to grow, research should prioritise understanding their interactive effects in shaping species relationships and ecosystem dynamics. Although the available evidence suggests that ALAN effects may vary between natural and man-made habitats, further research is needed to draw any general conclusion.

Biogenic reefs are known worldwide to play a key role in benthic ecosystems, enhancing biodiversity and ecosystem functioning at every level, from shallow to deeper waters. Unfortunately, several stressors threaten these vulnerable systems. The widespread presence of marine litter represents one of these. The harmful effects of marine litter on several organisms are known so far. However, only in the last decade, there was increasingly scientific and public attention on the impacts on reef organisms and habitats caused by litter accumulating on the seafloor. This review aims to synthesize literature and discuss the state of current knowledge on the interactions between marine litter and reef organisms in a strongly polluted basin, the Mediterranean Sea. The multiple impacts (e.g., entanglement, ghost-fishing, coverage, etc.) of litter on reef systems, the list of species impacted, and the main litter categories were identified, and a map of the knowledge available so far on this topic was provided. Seventy-eight taxa resulted impacted by marine litter on Mediterranean reefs, and the majority belonged to the phylum Cnidaria (41%), including endangered species like the red coral (Corallium rubrum) and the madrepora coral (Madrepora oculata). Entanglement, caused mainly by abandoned, lost or otherwise discarded fishing gear (ALDFG), was the most frequent impact, playing a detrimental effect mainly on coralligenous arborescent species and cold-water corals (CWCs). The information was spatially heterogeneous, with some areas almost uncovered by scientific studies (e.g., the Aegean-Levantine Sea and the Southern Mediterranean Sea). Although many legal and policy frameworks have been established to tackle this issue (e.g., Marine Strategy Framework Directive and the Barcelona Convention), several gaps still exist concerning the assessment of the impact of marine litter on marine organisms, and in particular on reefs. There is a need for harmonized and standardized monitoring protocols for the collection of quantitative data to assess the impact of litter on reefs and animal forests. At the same time, urgent management measures limiting, for instance, the impact of ALDFG and other marine litter are needed to preserve these valuable and vulnerable marine ecosystems.

Anthropic structures have been deployed in aquatic environments for the most variable purposes. Here, we review the use of artificial aquatic habitats (AAHs) worldwide through a systematic and comprehensive search of peer-reviewed literature. We aimed to synthesize the knowledge on the subject, identify gaps, and propose new perspectives for future research. In total, 460 peer-reviewed papers from 1972 to mid-2016 were included in our systematic review. Field studies carried out in marine temperate environments were predominant, whereas fewer efforts have been made in marine tropical and freshwater ecosystems. Experimental habitats made of concrete were the most common artificial structures. Visual census was the most used sampling method, and there was a dominance of short-term (< 12 months) and shallow waters (< 5 m depth) studies. Fish was the most studied group (18%), whereas tunicates encompassed the large proportion of non-native species associated with AAHs (32.9%). Although idealized for the promotion of biodiversity, AAHs have been serving as stepping stones for non-native invasive species, facilitating biotic homogenization by increasing the connectivity of hard-bottom systems. The scarcity of studies in coastal tropical and freshwater ecosystems, as well as the efforts with reduced temporal scales and restricted depths, calls for future research to better understand the role of artificial habitats, especially in climate change scenarios. In this sense, we provide a conceptual framework exploring major issues regarding AAHs, including biodiversity status, ecosystem services, and climate change, in order to guide future research and assist conservation measures.

A carbon budget for the northwest European continental shelf seas (NWES) was synthesised using available estimates for coastal, pelagic and benthic carbon stocks and flows. Key uncertainties were identified and the effect of future impacts on the carbon budget were assessed. The water of the shelf seas contains between 210 and 230 Tmol of carbon and absorbs between 1.3 and 3.3 Tmol from the atmosphere annually. Off-shelf transport and burial in the sediments account for 60-100% and 0-40% of carbon outputs from the NWES, respectively. Both of these fluxes remain poorly constrained by observations and resolving their magnitudes and relative importance is a key research priority. Pelagic and benthic carbon stocks are dominated by inorganic carbon. Shelf sediments contain the largest stock of carbon, with between 520 and 1600 Tmol stored in the top 0.1 m of the sea bed. Coastal habitats such as salt marshes and mud flats contain large amounts of carbon per unit area but their total carbon stocks are small compared to pelagic and benthic stocks due to their smaller spatial extent. The large pelagic stock of carbon will continue to increase due to the rising concentration of atmospheric CO2, with associated pH decrease. Pelagic carbon stocks and flows are also likely to be significantly affected by increasing acidity and temperature, and circulation changes but the net impact is uncertain. Benthic carbon stocks will be affected by increasing temperature and acidity, and decreasing oxygen concentrations, although the net impact of these interrelated changes on carbon stocks is uncertain and a major knowledge gap. The impact of bottom trawling on benthic carbon stocks is unique amongst the impacts we consider in that it is widespread and also directly manageable, although its net effect on the carbon budget is uncertain. Coastal habitats are vulnerable to sea level rise and are strongly impacted by management decisions. Local, national and regional actions have the potential to protect or enhance carbon storage, but ultimately global governance, via controls on emissions, has the greatest potential to influence the long-term fate of carbon stocks in the northwestern European continental shelf.

Making up over 92% of life in our oceans, marine invertebrates inhabit every zone in the water column, with contributions ranging from ecosystem functioning to socioeconomic development. Compared to charismatic species, marine invertebrates are often underrepresented in IUCN reports and national conservation efforts. Because of this, as climate change intensifies in conjunction with increasing anthropogenic pressures such as habitat destruction, many marine invertebrates are at risk of silently heading toward extinction. However, public perception has shifted in recent years due to the growing awareness of the important roles these invertebrates play in marine and human life. This change may promote greater support for future research and conservation campaigns of key species. This review highlights the importance of marine invertebrates, the environmental and anthropogenic stressors they are currently facing, and the inherent challenges in their successful conservation. Potential solutions to fill the gaps in current knowledge will be also explored in the context of recent globalization and technological advancements. The loss of marine invertebrate biodiversity will have cascading ecological, economic, and sociological repercussions, so compiling key information into a holistic review will add to the conversation of the importance of global marine invertebrate conservation.

Coralline algae are foundation species in many ecosystems they inhabit, acting as a settlement substrate, and binding together and even creating reefs in some locations. Ocean acidification is known to be a major threat to coralline algae. However, the effects of ocean warming are less certain. Here we bring multiple lines of evidence together to discuss the potential impacts of ocean warming on these ecologically crucial taxa. We use a meta-analysis on across 40 responses within the 14 different studies available that have assessed the effects of increasing temperature on coralline algal calcification in laboratory experiments. We do find a net negative impact of increasing temperature on coralline algal calcification at 5.2° C above ambient conditions under the singular effects of warming. Conversely, similar effects are seen when temperature drops below 2.0° C from ambient conditions. We propose that some coralline algae will be more capable of both acclimating and locally adapting to increasing ocean temperatures over the coming decades. This is due to the fact that many species possess short generation times, the ability to opportunistically rapidly utilise open space, and relatively high phenotypic plasticity compared to other important benthic species (e.g. corals). However, long-lived species, those with long generation times, or with narrow thermal tolerances could be at particular risk from ocean warming. Additionally, ocean warming will occur simultaneously with ocean acidification, a potentially greater threat to coralline algae, which could also reduce this tolerance to ocean warming in many species. We give key recommendations that will maximise the potential for future research to accurately determine how coralline algae will respond to future ocean warming.

Hypoxia is an increasing problem in marine ecosystems around the world. While major advances have been made in our understanding of the drivers of hypoxia, challenges remain in describing oxygen dynamics in coastal regions. The complexity of many coastal areas and lack of detailed in situ data have hindered the development of models describing oxygen dynamics at a sufficient spatial resolution for efficient management actions to take place. It is well known that the enclosed nature of seafloors and reduced water mixing facilitates hypoxia formation, but the degree to which topography contributes to hypoxia formation and small-scale variability of coastal hypoxia has not been previously quantified. We developed simple proxies of seafloor heterogeneity and modeled oxygen deficiency in complex coastal areas in the northern Baltic Sea. According to our models, topographical parameters alone explained ∼80 % of hypoxia occurrences. The models also revealed that less than 25 % of the studied seascapes were prone to hypoxia during late summer (August–September). However, large variation existed in the spatial and temporal patterns of hypoxia, as certain areas were prone to occasional severe hypoxia (O2 < 2 mg L−1), while others were more susceptible to recurrent moderate hypoxia (O2 < 4.6 mg L−1). Areas identified as problematic in our study were characterized by low exposure to wave forcing, high topographic shelter from surrounding areas and isolation from the open sea, all contributing to longer water residence times in seabed depressions. Deviations from this topographical background are probably caused by strong currents or high nutrient loading, thus improving or worsening oxygen status, respectively. In some areas, connectivity with adjacent deeper basins may also influence coastal oxygen dynamics. Developed models could boost the performance of biogeochemical models, aid developing nutrient abatement measures and pinpoint areas where management actions are most urgently needed.

Digital photography is widely used by coral reef monitoring programs to assess benthic status and trends. In addition to creating a permanent archive, photographic surveys can be rapidly conducted, which is important in environments where bottom-time is frequently limiting. However, substantial effort is required to manually analyze benthic images; which is expensive and leads to lags before data are available. Using previously analyzed imagery from NOAA’s Pacific Reef Assessment and Monitoring Program, we assessed the capacity of a trained and widely used machine-learning image analysis tool – CoralNet (coralnet.ucsd.edu) - to generate fully-automated benthic cover estimates for the main Hawaiian Islands (MHI) and American Samoa. CoralNet was able to generate estimates of site-level coral cover for both regions that were highly comparable to those generated by human analysts (Pearson’s r > 0.97, and with bias of 1% or less). CoralNet was generally effective at estimating cover of common coral genera (Pearson’s r > 0.92 and with bias of 2% or less in 6 of 7 cases), but performance was mixed for other groups including algal categories, although generally better for American Samoa than MHI. CoralNet performance was improved by simplifying the classification scheme from genus to functional group and by training within habitat types, i.e., separately for coral-rich, pavement, boulder, or ‘other’ habitats. The close match between human-generated and CoralNet-generated estimates of coral cover pooled to the scale of island and year demonstrates that CoralNet is capable of generating data suitable for assessing spatial and temporal patterns. The imagery we used was gathered from sites randomly located in <30 m hard-bottom at multiple islands and habitat-types per region, suggesting our results are likely to be widely applicable. As image acquisition is relatively straightforward, the capacity of fully-automated image analysis tools to minimize the need for resource intensive human analysts opens possibilities for enormous increases in the quantity and consistency of coral reef benthic data that could become available to researchers and managers.

Coral reefs are exceptionally biodiverse, and human dependence on their ecosystem services is high. Reefs experience significant direct and indirect anthropogenic pressures, and provide a sensitive indicator of coastal ocean health, climate change and ocean acidification, with associated implications for society. Monitoring coral reef status and trends is essential to better inform science, management and policy, but the projected collapse of reef systems within a few decades makes the provision of accurate and actionable monitoring data urgent. The Global Coral Reef Monitoring Network has been the foundation for global reporting on coral reefs for two decades, and is entering into a new phase with improved operational and data standards incorporating the Essential Ocean Variables (EOVs) (www.goosocean.org/eov) and Framework for Ocean Observing developed by the Global Ocean Observing System. Three EOVs provide a robust description of reef health: hard coral cover and composition, macro-algal canopy cover, and fish diversity and abundance. A data quality model based on comprehensive metadata is designed to facilitate maximum global coverage of coral reef data, and tangible steps to track capacity building. Improved monitoring of events such as mass bleaching and disease outbreaks, citizen science and socio-economic monitoring have the potential to greatly improve the relevance of monitoring to managers and stakeholders, and to address the complex and multi- dimensional interactions between reefs and people. XX THERE IS SOMETHING WRONG IN THE ABSTRACT WORD LIMIT, ONE MORE PARAGRAPH WAS INCLUDED IN THE ORIGINAL TEXT!!

Flooding, a sudden disturbance, is considered to affect negatively the survival of fish by causing shock and growth, especially for species living in headwaters of a river. Neolissochilus benasi is a freshwater fish that prefers living in clean, flowing water and rocky bottoms with sands and gravels. Based on a segment in mtDNA obtained from eight specimens collected from northern Vietnam, the present study applied a hybrid novel, genetic algorithm (GA)–artificial neural network (ANN) to understand impacts of floods on N. benasi. The GA–ANN hybrid model was successful in mapping flood susceptibility, which correlates with river density, altitude, and rainfall, being typical in lowlands, along rivers and streams. Strong correlations were found between fish and urban density, agriculture, and land use/land cover, which contribute to the decrease of N. benasi. Habitat destruction, hydropower dams, pollution, overfishing, and using destructive gears are probably the main causes of the N. benasi decline. Importantly, based on GA–ANN model, flooding had a significant impact on N. benasi, which performs a low genetic diversity in the studied regions. Thus, this endangered freshwater fish species would have been easily affected by flooding since very high and high susceptibility of N. benasi was abundant in the province, particularly along the Red River and urban areas. This is the first study to examine the link between flooding and genetic diversity of an aquatic organism in Vietnam applying deep learning models. Accordingly, these results recommend significant suggestions to protect N. benasi in its habitats from northern Vietnam under flooding.