Fire ecology in marine systems.

Wildfire byproducts enter into the oceans via terrestrial and atmospheric routes. They pose a challenge to the sustainability of marine ecosystems, especially under the current increase in fire activity. Research is needed to unravel the dynamics between wildfires and marine life, and the oceans' potential to mitigate wildfire emissions.

Temporal and inter-individual changes in the integrated biochemical condition of the gonads of female swordfish (Xiphias gladius) from the Southeastern Pacific Ocean.

The integrated biochemical condition (IBC) of gonads is closely related to the reproductive success of highly migratory marine species. The IBC of gonads can be influenced not only by size and/or age, but also by environmental conditions. Here, female swordfish, Xiphias gladius, that migrate to temperate regions with a marked seasonality (e.g., the Southeastern Pacific Ocean, SEPO) were compared in relation to the IBCs (lipids, proteins, glucose and, fatty acid profiles) of their gonads; individuals with two body size ranges and distinct degrees of sexual maturity were evaluated, and considered as: small and/or virginal (SV: <170 cm lower jaw fork-length (LJFL), oocyte size (OS) <0.08 mm) vs large and/or maturing females (LM: >190 cm LJFL, OS >0.133 mm). This comparison was conducted in two environmentally contrasting seasons (winter vs spring). Our results showed that the gonadosomatic index (GSI) was significantly higher in LM than SV. Lipid contents varied significantly between seasons and body sizes. The highest lipid concentrations were recorded in the spring in large females. No significant differences were found when comparing the protein and glucose contents of the two evaluated seasons or body size ranges of the studied females. In turn, the fatty acid (FA) profiles of female gonads significantly varied for both seasons and body size ranges. A high content of saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs) and poly-unsaturated fatty acids (PUFAs) were recorded in female gonads in the spring. The SFAs C16:0 and C18:0, the MUFA C18:1n9, and the essential PUFA C22:6n3 were the main contributors to the observed differences between spring and winter. These results could be used as indicators of the nutritional condition and health status of swordfish individuals. Hence, the IBC of female swordfish gonads have great potential to aid in estimating survival rates and stock abundances of this species. The integration of this information constitutes an asset in fishery management models with an ecosystem approach.

Pleistocene expansion, anthropogenic pressure and ocean currents: Disentangling the past and ongoing evolutionary history of Patella aspera Röding, 1798 in the archipelago of Madeira.

AIMS: Rising sea-level following the Last Glacial Maximum lead to fragmentation of coastal limpet populations between islands of the Archipelago of Madeira. This fragmentation is reinforced by recent heavy exploitation reducing effective population size on Madeira Island. We use the limpet P. aspera to understand how the role of processes at different time scales (i.e. changes in the sea level and overexploitation) can influence the genetic composition of an extant species, relating these processes to reproductive phenology and seasonal shifts in ocean currents. LOCATION: Madeira Island, Porto Santo and Desertas (Archipelago of Madeira, NE Atlantic Ocean). TAXON: The limpet Patella aspera. METHODS: Twelve microsatellite genetic markers were used. A power analysis was used to evaluate the power of the microsatellite markers to detect a signal of population differentiation. Long-term past migrations were assessed using a Bayesian Markov Montecarlo approach in the software MIGRATE-n to estimate mutation-scaled migration rates (M = m/µ; m, probability of a lineage immigrating per generation; µ, mutation rate). Two scenarios were evaluated using an Approximate Bayesian Computation (ABC) in the software DIYABC 2.1 (i) Scenario 1: considered a population scenario from a reduced Ne at time t3 to a higher Ne at time t2; and (ii) Scenario 2 considering a reduction of Ne from a time t3 to a time t2. RESULTS: Colonization of the archipelago by Portuguese settlers six centuries ago probably led to an important decrease in the genetic diversity of the species (Ne). Contemporary gene flow strongly support a pattern of high asymmetric connectivity explained by the reproductive phenology of the species and spatio-temporal seasonal changes in the ocean currents. Spatio-temporal reconstructions using Bayesian methods, including coalescent and Approximate Bayesian Computation (ABC) approaches, suggest changes in the migration patterns from highly symmetric to highly asymmetric connectivity with subtle population differentiation as consequence of post-glacial maximum sea level rise during the Holocene. MAIN CONCLUSIONS: Our results suggest that anthropogenic activity could have had serious effects on the genetic diversity of heavily exploited littoral species since the end of the Pleistocene, probably accelerating in recent years.

Epibenthic communities from offshore platforms in the Arabian Gulf are structured by platform age and depth.

Oil and gas platforms act as artificial habitats for a myriad of marine organisms. In this study, we used opportunistic remotely operated vehicle (ROV) data to describe fouling assemblages through the characterization of functional groups in the Al Shaheen oil field, situated in Qatari waters. The surveys showed a strong vertical stratification, with the number of functional groups increasing from the surface to the bottom. In addition, the majority of functional groups had their highest frequency of occurrence in the 35-60 m interval. In turn, multivariate analyses showed a slight structure among platforms with different ages. The lowest number of functional groups occurred in the early ages (2-3 years old), and some groups either increased or decreased their frequency and abundance along the years. A step further is now required to determine whether these platform foundations should be converted to reefs after their decommissioning (i.e., Rigs to Reefs approach).

Major ocean currents may shape the microbiome of the topshell Phorcus sauciatus in the NE Atlantic Ocean.

Studies on microbial communities are pivotal to understand the role and the evolutionary paths of the host and their associated microorganisms in the ecosystems. Meta-genomics techniques have proven to be one of the most effective tools in the identification of endosymbiotic communities of host species. The microbiome of the highly exploited topshell Phorcus sauciatus was characterized in the Northeastern Atlantic (Portugal, Madeira, Selvagens, Canaries and Azores). Alpha diversity analysis based on observed OTUs showed significant differences among regions. The Principal Coordinates Analysis of beta-diversity based on presence/absence showed three well differentiated groups, one from Azores, a second from Madeira and the third one for mainland Portugal, Selvagens and the Canaries. The microbiome results may be mainly explained by large-scale oceanographic processes of the study region, i.e., the North Atlantic Subtropical Gyre, and specifically by the Canary Current. Our results suggest the feasibility of microbiome as a model study to unravel biogeographic and evolutionary processes in marine species with high dispersive potential.

Severe shifts of Zostera marina epifauna: Comparative study between 1997 and 2018 on the Swedish Skagerrak coast.

The interaction between bottom-up and top-down processes in coastal ecosystems has been scarcely studied so far. Temporal changes in trophic interactions of Zostera marina along the Swedish west coast are relatively well studied, with the exception of epifaunal communities. Epifauna was used as a model study to explore resource (bottom-up) or predator (top-down) regulated in a vegetated ecosystem. We conducted a 21-year comparative study (1997 and 2018) using epifauna of 19 Zostera marina meadows along the Swedish Skagerrak coast. Large changes were observed in the composition of small (0.2-1 mm) and large (>1 mm) epifauna. In the small-sized epifauna, the nematode Southernia zosterae and harpacticoids showed an increase of 90% and a decrease of 50% of their abundances, respectively. In the large-sized epifauna, the polychaete Platynereis dumerilii and chironomid larvae were absent in 1997 but thrived in 2018 (>2000 ind. m-2). Mesoherbivores (Idoteids and gammarids) were locally very abundant in 1997 but disappeared in 2018. An 83% decline of mytilids settling in Zostera marina leaves was observed. Our results showed that epifauna is predominantly top-down regulated. An integrative framework of the study area is outlined to shed light on the causes and consequences of the environmental shifts reported in Zostera meadows from the northern Skagerrak area throughout the last three decades.

Marine protected areas are more effective but less reliable in protecting fish biomass than fish diversity.

Marine protected areas (MPAs) provide multiple conservation benefits, thus raising the question of how good and consistent they are at their roles. Here, we quantified three components, namely, diversity, biomass, and other relevant variables, in numerous protected and unprotected areas across four marine ecoregions in south-western Europe. We created a "global conservation status index" (CSIglobal) as the sum of CSIdiversity, CSIbiomass, and CSIrelevant. We then tested whether CSI and its three components varied as a function of protection and marine ecoregion. MPA efficiency, defined as the effect size of protection on CSIglobal, was unreliable and varied with geography. CSIbiomass and CSIrelevant contributed to the unreliability of MPA efficiency, while CSIdiversity was reliable. CSIbiomass showed the major efficiency in protected areas (60%). Biomass of threatened species was the single largest variable that contributed to MPA efficiency. Our easy-to-use approach can identify high- and low-efficient MPAs and help to clarify their actual roles.

Consequences of marine barriers for genetic diversity of the coral-specialist yellowbar angelfish from the Northwestern Indian Ocean.

Ocean circulation, geological history, geographic distance, and seascape heterogeneity play an important role in phylogeography of coral-dependent fishes. Here, we investigate potential genetic population structure within the yellowbar angelfish (Pomacanthus maculosus) across the Northwestern Indian Ocean (NIO). We then discuss our results with respect to the above abiotic features in order to understand the contemporary distribution of genetic diversity of the species. To do so, restriction site-associated DNA sequencing (RAD-seq) was utilized to carry out population genetic analyses on P. maculosus sampled throughout the species' distributional range. First, genetic data were correlated to geographic and environmental distances, and tested for isolation-by-distance and isolation-by-environment, respectively, by applying the Mantel test. Secondly, we used distance-based and model-based methods for clustering genetic data. Our results suggest the presence of two putative barriers to dispersal; one off the southern coast of the Arabian Peninsula and the other off northern Somalia, which together create three genetic subdivisions of P. maculosus within the NIO. Around the Arabian Peninsula, one genetic cluster was associated with the Red Sea and the adjacent Gulf of Aden in the west, and another cluster was associated with the Arabian Gulf and the Sea of Oman in the east. Individuals sampled in Kenya represented a third genetic cluster. The geographic locations of genetic discontinuities observed between genetic subdivisions coincide with the presence of substantial upwelling systems, as well as habitat discontinuity. Our findings shed light on the origin and maintenance of genetic patterns in a common coral reef fish inhabiting the NIO, and reinforce the hypothesis that the evolution of marine fish species in this region has likely been shaped by multiple vicariance events.

Interspecific variation in the physiological and reproductive parameters of porcelain crabs from the Southeastern Pacific coast: potential adaptation in contrasting marine environments.

Porcelain crabs inhabit from upper intertidal to subtidal habitats. These environments are characterized by highly variable environmental conditions, which subject species found in these habitats to stress. In this study, we compared reproductive traits of mothers [i.e. fecundity, reproductive output (RO), dry weight, organic matter] and physiological parameters of their offspring (i.e. wet weight, water content, dry weight, organic matter, lactate content of embryos) of three species of porcelain crabs that inhabit the Southeastern Pacific: Petrolisthes laevigatus (upper intertidal); P. violaceus (low intertidal); Allopetrolisthes punctatus (subtidal). Overall, female P. laevigatus had lower fecundity (802 ± 115 vs. 4181 ± 1097 embryos) and amount of organic matter in their embryo masses (0.053 ± 0.006 vs. 0.27 ± 0.025 g) but higher RO values (1.34 ± 0.34 vs. 0.20 ± 0.07) than Allopetrolisthes punctatus. In addition, P. laevigatus embryos had higher organic matter content (81.09 ± 28.8 vs. 64.54 ± 6.1 µg), higher water content (188.6 ± 91.9 vs. 152.4 ± 30.8 µL) and higher lactate content (0.26 ± 0.04% vs. 0.07 ± 0.01% dry weight) than that found in A. punctatus embryos. Furthermore, females and embryos of P. violaceus showed low values and similar to those observed in P. laevigatus. As a potential strategy to increase survival of the offspring, P. laevigatus seems to invest a large portion of its energy in production of high quality embryos, despite costs to fecundity. This study reveals that porcelain crabs have physiological adaptations during their ontogeny that allow them to survive in fluctuating environments.

Building up marine biodiversity loss: Artificial substrates hold lower number and abundance of low occupancy benthic and sessile species.

Ocean sprawl is replacing natural substrates with artificial alternatives. We hypothesized that, after submersion, high occupancy, high mobility species colonize artificial substrates faster than low occupancy, low mobility species, a biodiversity divergence that will slowly fade out with time. Using quantitative visual census of species in 10 artificial and their adjacent natural substrates, we tested for the existence and temporal evolution of this divergence. Assigning species to one of three occupancy and one of three mobility categories, we found that artificial substrates increased the performance of high mobility, high occupancy species while decreased the performance of low occupancy species with medium and low mobility. This biodiversity divergence remained unchanged over the 50-year underwater timespan of the artificial substrates investigated. Our results suggest that proliferation of artificial substrates is building up a biodiversity loss driven by the least conspicuous and uncommon benthic and sessile species that is undermining coastal marine biodiversity.

New Data on the Systematics of Comb-fin Squids Chtenopteryx spp. (Cephalopoda: Chtenopterygidae) from the Canary Islands.

Alejandro Escánez, Álvaro Roura, Rodrigo Riera, Ángel Francisco González, and Ángel Guerra (2018) The systematics of the comb-fin squid species is problematic and poorly resolved. In total, 53 specimens of comb-fin squids (Chtenopteryx spp.) were caught at depths ranging from 30 to 800 m off the Canary Islands (NE Atlantic Ocean). Mantle lengths of the individuals ranged from 18 to 43 mm and the sample included immature, mature male and mature female specimens. Two species of comb-fin squids, Chtenopteryx canariensis and C. sicula, were identified by combining traditional morphological characters with a molecular analysis of a fragment of the cytochrome c oxidase subunit I (COI) gene. Intra- and interspecific genetic distances and maximum likelihood tree analyses based on COI sequences available from GenBank suggest the existence of at least four species, two from the Pacific and two from the Atlantic Ocean. Our data expand the current geographic range of C. canariensis from the NE to NW Atlantic. In the GenBank database, several sequences of comb-fin squid in different species-specific clades have been attributed only to C. sicula, indicating the possible existence of cryptic species and the need to re-analyse these data.

Ecology: Science or philately? An interdisciplinary analysis of sustainability by exploring if it is possible to get more and more information by reducing collateral environmental damages.

We herein explore the connections between the current condition of ecology concerning to sustainable development and the statement of Rutherford regarding the importance of physics to understand sustainability and biological conservation. The recent emergence of organic biophysics of ecosystems (OBEC) may constitute a feasible alternative to fill the gap between conventional ecological thinking and physics, especially thermodynamics. However, our comprehension of sustainability and biological conservation is influenced by the interactions between information and entropy, because we tend to exclude parts of the biosphere as well as their relationships among them. We explore the use of a holistic analysis of sustainability and biological conservation using physics, and also establish a parallelism between Maxwell's demons and human beings. Lastly, the ecological meaning of the hypothetical feasibility of Maxwell's demon at the anthroposphere scale is analyzed starting from the objections of von Smoluchowski, Szilard and Bennet.

New data on the Tanaidacea (Crustacea: Peracarida) from the Canary Islands, with a description of a new species of Apseudopsis.

Benthic samples from two harbours at El Hierro and Tenerife (Canary Islands) yielded three species of Tanaidacea. Tanais dulongii and Leptochelia savignyi are recorded for the first time in Tenerife and El Hierro, respectively. A new species of Apseudomorpha, Apseudopsis rogi, was collected in both harbours and can be differentiated from other species of the genus by the male having a cheliped merus with a distinctive, cylindrical dorso-proximal spur. This is the first species of Apseudopsis described for the Macaronesian region. A key to the Atlantic and Mediterranean species of Apseudopsis is provided.

Clear regression of harvested intertidal mollusks. A 20-year (1994-2014) comparative study.

Intertidal mollusks are subjected to an intense environmental pressure, from human-induced stressors, mainly harvesting, to competition for food and space with other species. Here we used mollusk shell size as a measure of size distribution and reproductive potential of intertidal limpets. Two species of exploited limpets (Patella candei crenata and Patella aspera) were monitored throughout the littoral of Tenerife (Canary Islands, NE Atlantic Ocean), an overpopulated island with a high coastal pressure. The exploitation of these two limpet species is controlled by regional legislation, with seasonal closures and limits of harvest for professional (10 kg) and recreational harvesters (3-5 kg). A long-term comparison (1994-2014) of limpet size has been conducted as a surrogate of the state of conservation of these two limpets. Both species showed populations dominated largely by small-sized individuals (<30 mm) and a lack of large adults (>60 mm). The proximity to coastal settlements was not a factor to explain limpet assemblage structure. The temporal (1994-2014) comparative study showed a sharp decrease in the mean size of both limpet species (7 mm in P. aspera and 5 mm in P. candei crenata). These results might be indicative of overharvesting of both species in Tenerife. The conservation of the two studied species needs to be accomplished by the strict fulfillment of current protective strategies, as well as the creation of marine protected areas where intertidal harvesting is totally banned all over the year.

Out of sight, out of mind: threats to the marine biodiversity of the Canary Islands (NE Atlantic Ocean).

Lack of knowledge of the marine realm may bias our perception of the current status and threats to marine biodiversity. Less than 10% of all ecological literature is related to the ocean, and the information we have on marine species that are threatened or on the verge of extinction is scarce. This lack of information is particularly critical for isolated areas such as oceanic archipelagos. Here we review published and grey literature on the current status of marine organisms in the Canary Islands as a case description of the consequences that current out-of-sight out-of-mind attitudes may have on this unique environment. Global change, as represented by coastal development, pollution, exotic species and climate change, are currently affecting the distribution and abundance of Canarian marine organisms, and pose multiple threats to local species and communities. Environmental risks are significant at community and species levels, particularly for threatened species. Failure to address these trends will result in shifts in local biodiversity with important ecological, social, and economic consequences. Scientists, policy makers, educators, and relevant societal groups need to collaborate to reverse deleterious coastal biodiversity trends.

Ecological structure and function differs between habitats dominated by seagrasses and green seaweeds.

Marine vegetated habitats, e.g. seagrass meadows, deliver essential functions and services to coastal ecosystems and human welfare. Impacts induced by humans, however, have facilitated the replacement of seagrasses by alternative vegetation, e.g. green rhizophytic seaweeds. The implications of habitat shifts for ecosystem attributes and processes and the services they deliver remain poorly known. In this study, we compared ecosystem structure and function between Cymodocea nodosa seagrass meadows and bottoms dominated by Caulerpa prolifera, a green, native, rhizophytic seaweed, through 5 ecological proxies: (i) primary production (via community metabolism), (ii) composition and abundance of epifauna (a proxy for provision of habitat for epifauna), composition and abundance of (iii) small-sized (juvenile) and (iv) large-sized (adult) fishes (proxies for provision of habitat for fishes), and (v) sediment retention (a proxy for sediment stabilization). Four of these proxies were greater in C. nodosa seagrass meadows than in C. prolifera beds: gross primary productivity (∼1.4 times), the total abundance, species density and biomass of small-sized fishes (∼2.1, 1.3 and 1.3 times, respectively), the total abundance and species density of large-sized fishes (∼3.6 and 1.5 times, respectively), and sediment stabilization (∼1.4 times). In contrast, the total abundance and species density of epifauna was larger (∼3.1 and 1.7 times, respectively) in C. prolifera than in C. nodosa seagrass beds. These results suggest that ecosystem structure and function may differ if seagrasses are replaced by green rhizophytic seaweeds. Importantly, ecosystem functions may not be appropriate surrogates for one another. As a result, assessments of ecosystem services associated with ecosystem functions cannot be based on exclusively one service that is expected to benefit other services.

Long-term monitoring of fish farms: application of Nematode/Copepod index to oligotrophic conditions.

Interannual variability (2003-2008) of meiofaunal assemblages were analyzed in sediments beneath fish cages (Impact group) and in areas not affected by aquaculture activities (Control group). Organisms responded with spatial and seasonal variation in meiofauna assemblages, with an abrupt increase of abundances in locations beneath fish cages throughout the study period. This increase was greater during the last sampling year (2008) and mainly due to high abundances of nematodes. Univariate analyses showed differences between control and impacted sites at both sites, however, only significant variations were found in Los Gigantes, which are consistent with seasonal meiofauna variations throughout the study period. These results are partially explained by differences in current velocity between both sampling areas. The Ne/Co index showed the same trend and it seems to be a reliable index in sediment slightly affected by aquaculture wastes. This index is especially recommended in oligotrophic areas (e.g. Canary Islands) where meiofaunal assemblages are poorly represented in terms of abundances.