Condor Seamount Research Articles

Tidal to decadal scale hydrodynamics at two contrasting cold-water coral sites in the Northeast Atlantic

Cold-water corals (CWCs) thrive in areas with complex and rough topography favoring the development of highly diverse benthic communities. Several biotic and abiotic factors including organic matter supply, temperature, bottom roughness and currents are important drivers of ecosystem structure and functioning in deep-sea environments at different spatial and temporal scales. Little is known, however, how basin-scale changes in the ocean climate affect these drivers at local scales. Here, we use high-resolution implementations of the hydrodynamic model ROMS-AGRIF for estimating characteristic spatial and temporal scales of local hydrodynamics in response to variations of basin-scale currents imposed by distinct changes of the Atlantic Meridional Overturning Circulation (AMOC) in the past century. We focus on two CWC communities on the SE Rockall Bank slope and at Condor Seamount. We considered two contrasting AMOC states that were identified from the 1958–2009 hindcast of the 1/20° resolution VIKING20 North Atlantic basin-scale ocean circulation model and used as boundary conditions for the high-resolution local area models. At SE Rockall Bank, variability of near-bottom currents in both regions was largely dominated by tidal dynamics, but strongly modified by AMOC induced basin-scale variations of water mass properties and bottom currents. During strong AMOC years, waters in the main CWC depth corridor (600–1200 m) were cooler and less saline but were dominated by stronger bottom currents when compared with conditions during weak AMOC years. At Condor Seamount, bottom currents were largely unaffected by AMOC related changes close to the summit at water depths < 400 m. Kinetic energy dissipation rates derived from the 3D near-bottom velocity field appeared to positively relate with the in-situ CWC distribution. Kinetic energy dissipation is therefore proposed as a mechanistic descriptor of CWC presence as it provides a more mechanistic view of hydrodynamics driving organic matter supply to filter and suspension-feeding communities.

Benthic O2 uptake by coral gardens at the Condor seamount (Azores)

Using the non-invasive aquatic eddy covariance technique, we provide the first oxygen (O2) uptake rates from within coral gardens at the Condor seamount (Azores). To explore some of the key drivers of the benthic O2 demand, we obtained benthic images, quantified local hydrodynamics, and estimated phototrophic biomass and deposition dynamics with a long-term moored sediment trap. The coral gardens were dominated by the octocorals Viminella flagellum and Dentomuricea aff. meteor. Daily rates of O2 uptake within 3 targeted coral garden sites (203 to 206 m depth) ranged from 10.0 ± 0.88 to 18.8 ± 2.0 mmol m-2 d-1 (mean ± SE) and were up to 10 times higher than 2 local sandy reference sites within the seamount summit area. The overall mean O2 uptake rate for the garden (13.4 mmol m-2 d-1) was twice the global mean for sedimentary habitats at comparable depths. Combined with parallel ex situ incubations, the results suggest that the octocorals might contribute just ~5% of the observed O2 uptake rates. Deposition of particulate organic matter (POM) assessed by the sediment trap accounted for less than 10% of the O2 demand of the coral garden, implying a substantial POM supply circumventing the deployed traps. Our results expand the database for carbon turnover rates in cold-water coral habitats by including the first estimates from these largely understudied coral gardens.

Temporal dynamics in diversity patterns of fish sound production in the Condor seamount (Azores, NE Atlantic)

Fish sounds are important components of Azorean soundscapes. Therefore, unraveling their patterns can contribute to a better assessment of local biodiversity dynamics.Passive Acoustic Monitoring (PAM) is a cost-effective, non-intrusive method providing long-term information regardless of weather or logistic conditions, which can be especially useful when monitoring remote areas. Using PAM, we assess temporal dynamics of fish vocal activity in a protected seamount and validate PAM as an important tool for biodiversity assessment in deep-sea fish communities. Thus, we evaluated the annual, seasonal and diel patterns of variation of putative fish sounds identified in an Azorean protected seamount, the Condor (ca.190 m depth). Here, 3 years (2008, 2010 and 2012) of acoustic data were collected and analysed for diversity and abundance of the most prevalent fish sounds. We compared abundance and diversity of fish sounds before and after the establishment of the marine protected area in 2010, to assess its initial protection effects. We also compared abundance and biodiversity measures (richness and Shannon diversity index) of acoustic data with fishing data from deep-water longline surveys, to verify if acoustic diversity and taxonomic diversity show a similar trend. Additionally, we estimated a likely distance range of fish sound sources from the acoustic data loggers for local background noise and typical fish sound levels. Estimated detection distance of different fish sounds, considering Condor background noise level and reported fish sound source levels, were typically larger than 10 m and could reach hundreds of meters in some species suggesting that this study potentially targeted sounds of the deep-sea fish fauna. Fish acoustic activity was prevalent at dusks and nights of all years, while no overall seasonal pattern was detected. However, one sound sequence (#1) was dominant in the autumns of all studied period. A decrease in abundance and richness of sounds was observed from 2008 to 2012 in line with the results of fishing surveys. Although unexpected, these consistent trends suggest that PAM provides a reliable representation of fish biodiversity dynamics. Taken together, this study shows that monitoring fish sounds with PAM is a valid and promising tool for fish biodiversity assessment in deep Azorean seamounts.

Underwater Ambient Noise in a Baleen Whale Migratory Habitat Off the Azores

Assessment of underwater noise is of particular interest given the increase in noise-generating human activities and the potential negative effects on marine mammals which depend on sound for many vital processes. The Azores archipelago is an important migratory and feeding habitat for blue (Balaenoptera musculus), fin (Balaenoptera physalus) and sei whales (Balaenoptera borealis) en route to summering grounds in northern Atlantic waters. High levels of low frequency noise in this area could displace whales or interfere with foraging behavior, impacting energy intake during a critical stage of their annual cycle. In this study, bottom-mounted Ecological Acoustic Recorders were deployed at three Azorean seamounts (Condor, Acores and Gigante) to measure temporal variations in background noise levels and ship noise in the 18-1,000 Hz frequency band, used by baleen whales to emit and receive sounds. Monthly average noise levels ranged from 90.3 dB re 1 μPa (Acores seamount) to 103.1 dB re 1 μPa (Condor seamount) and local ship noise was present up to 13% of the recording time in Condor. At this location, average contribution of local boat noise to background noise levels is almost 10 dB higher than wind contribution, which might temporally affect detection ranges for baleen whale calls and difficult communication at long ranges. Given the low time percentatge with noise levels above 120 dB re 1μPa found here (3.3 % at Condor), we woud expect limited behavioural responses to ships from baleen whales. Sound pressure levels measured in the Azores are lower than those reported for the Mediterranean basin and the Strait of Gibraltar. However, the currently unknown effects of baleen whale vocalization masking and the increasing presence of boats at the monitored sites underline the need for continuous monitoring to understand any long-term impacts on whales.

Persistent Enhancement of Micronekton Backscatter at the Summits of Seamounts in the Azores

Knowledge of the dynamics of micronekton at seamounts is critical to understanding the ecological role of these ecosystems. Active acoustic techniques are an effective tool to monitor the distribution and movements of pelagic organisms. We carried out several day- and nighttime active acoustic surveys over a 3-year period (2009-2011) to characterize the spatial and temporal distribution of micronekton backscatter on two seamounts (Condor and Gigante) in the Azores and in the surrounding open-waters. The highest mean volume backscattering strength (MVBS) was consistently found in the water column over the seamount summits, regardless of the season and diel period. MVBS over the summits was 14 to 26 times higher than over the slopes, and 10 times higher than in open-waters. Diel variations in backscatter intensity were more pronounced in open-waters and in Gigante seamount, with higher values during the day in open-waters, and at night over the summits and slopes of Gigante. Over Condor seamount, diel changes in backscatter intensity were small, but MVBS was generally higher at night than during the day, as in Gigante. Persistence of strong acoustic backscatter over the summits of Condor and Gigante seamounts is a key finding of this study and may be explained by the presence of a seamount-associated micronekton community and by the retention of vertically migrating micronekton. The latter hypothesis is consistent with observed day-night differences in backscatter, suggesting that nocturnal migrants may be passively transported or actively swim above seamount summits and slopes. Possible physical mechanisms leading to the observed patterns in micronekton distribution are discussed. This study contributes to a better understanding of how seamounts may influence the spatial and temporal dynamics of micronekton assemblages.

On the potential of an RST-based analysis of the MODIS-derived chl-a product over Condor seamount and surrounding areas (Azores, NE Atlantic)

Oceanographic cruises have been conducted on the Condor seamount (SW Faial Island, Azores archipelago, NE Atlantic) since 2009 to collect in situ data and understand potential seamount effects on local biodiversity. Satellite data have been concurrently collected to infer the space-time upper-ocean optical property variability and the associated physical processes. The main limitation of this analysis is the persistent and significant cloud coverage above the region that, especially in some seasons, can significantly hinder satellite data availability. This study was meant to test the robust satellite technique (RST) over the Condor seamount, assess its capability to estimate multiyear trends and identify space-time anomalies. To this aim, 11-year MODIS/AQUA level 2-derived chlorophyll-a (chl-a) data were used. Results achieved for October 2010 show, within a large-scale analysis, the presence of well-defined areas of near-surface chl-a anomalies, highlighting the occurrence of a trapping effect due to flow-topography interaction processes. Regarding the Condor area, the chl-a anomalies detected along the eastern side of the seamount were linked to a strong vertical mixing that provided sufficient inorganic nutrients requested for productivity. The achieved results, whose accuracy was also tested through a comparison with in situ data, are consistent with those independently obtained by other authors who described the phytoplankton variability around the Condor seamount. This study shows the high potential of the RST approach to assess the chl-a variability in the space-time domain in oligotrophic regions such as the Azores, allowing the identification of the most important areas to be preserved and/or managed.

A new species of Neostygarctus (Arthrotardigrada) from the Condor Seamount in the Azores, Northeast Atlantic

The tardigrade fauna of Condor Seamount, west of the Azores, is relatively rich, and species from at least seven genera are represented. A new species of the rare marine genus Neostygarctus (Arthrotardigrada) was found at 206 m depth at the summit of the seamount. This is the first record of the genus from the Atlantic Ocean, and also the deepest record of the genus. The new species Neostygarctus oceanopolis sp. nov. is easily distinguished from the Mediterranean type species N. acanthophorus by the number of middorsal spines. N. acanthophorus has five dorsal spines, whereas the adult of N. oceanopolis sp. nov. has seven. The cave tardigrade from Japan, Neostygarctus lovedeluxe also has dorsal spines on all five segments, but only the cephalic and the caudal segments have a middorsal spine, while the three other trunk segments have two spines on each of the dorsal segmental body plates. For the first time, ventral plates are recorded for a species of Neostygarctus. A membranous coating of the all spines of the cephalic segment, the lateral processes of the first three trunk segments, and the spines of the fourth leg pair are unique for Neostygarctus.

Changes in nematode communities in different physiographic sites of the condor seamount (north-East atlantic ocean) and adjacent sediments.

Several seamounts are known as ‘oases’ of high abundances and biomass and hotspots of biodiversity in contrast to the surrounding deep-sea environments. Recent studies have indicated that each single seamount can exhibit a high intricate habitat turnover. Information on alpha and beta diversity of single seamount is needed in order to fully understand seamounts contribution to regional and global biodiversity. However, while most of the seamount research has been focused on summits, studies considering the whole seamount structure are still rather poor. In the present study we analysed abundance, biomass and diversity of nematodes collected in distinct physiographic sites and surrounding sediments of the Condor Seamount (Azores, North-East Atlantic Ocean). Our study revealed higher nematode biomass in the seamount bases and values 10 times higher in the Condor sediments than in the far-field site. Although biodiversity indices did not showed significant differences comparing seamount sites and far-field sites, significant differences were observed in term of nematode composition. The Condor summit harboured a completely different nematode community when compared to the other seamount sites, with a high number of exclusive species and important differences in term of nematode trophic diversity. The oceanographic conditions observed around the Condor Seamount and the associated sediment mixing, together with the high quality of food resources available in seamount base could explain the observed patterns. Our results support the hypothesis that seamounts maintain high biodiversity through heightened beta diversity and showed that not only summits but also seamount bases can support rich benthic community in terms of standing stocks and diversity. Furthermore functional diversity of nematodes strongly depends on environmental conditions link to the local setting and seamount structure. This finding should be considered in future studies on seamounts, especially in view of the potential impacts due to current and future anthropogenic threats.

Interactions between fish species on seamount coral habitat

The behaviour of the scorpionfish Helicolenus dactylopterus and Pontinus kuhlii towards the zooplanktivores Anthias anthias and Callanthias ruber are described from rare in situ remote-operated vehicle (ROV) observations. The events were recorded by ROV SP on gorgonian habitats of Dentomuricea meteor and Viminella flagellum, at the summit of Condor seamount (212–223 m; Azores, Northeast Atlantic). Behaviour in both species included approaching the zooplanktivores from a sitting position, orientating the snout in front of the object and swimming in a straight line. After an initial slow displacement, it follows an adduction of dorsal, pectoral and anal fins and an increase in speed, occasionally accompanied of a burst swim. H. dactylopterus can reach up to 0.8 m above the seafloor, departing from more than 1.5m distance; P. kuhlii was observed only on one occasion, chasing A. anthias from 0.64-m distance, with average swimming velocities of 1–2 m/s. The possibility of predatory or agonistic behaviour is discussed, with more evidence being gathered towards the former, representing a possible linkage between the pelagic and the benthic realm.

Topographically induced circulation patterns and mixing over Condor seamount

Analysis of mean and oscillatory circulation patterns over Condor seamount, situated near the central group of the Azores islands, was performed. During 1.5 years of observations, at least half of the time an anticyclonic cap was established over the summit. The vortex was characterised by a strong asymmetry: it was shifted to the south of the summit and strongly stretched along the gentle eastern and western slopes of the seamount.Three mechanisms are suggested to generate the anticyclonic cap: impinging mean flow, tidal rectification, and vertical turbulent density fluxes. Our estimates suggest that tidal rectification alone can explain the formation of the observed anticyclonic cap, but the character of temporal variation of its intensity gives evidence that impinging flow also plays an important role in the cap dynamics. Conditions for stability of the anticyclonic cap are found to be principally different depending on the impinging flow being unidirectional or dominated by synoptic oscillations. For a unidirectional impinging flow, in close accordance with the theory, anticyclonic cap was readily formed over the top of the seamount. The cap was stable, except for the events of the cap shedding when the impinging flow accelerated above a critical level. When the impinging flow varied its direction, dominated by topographic Rossby waves, the anticyclonic cap was absent or its intensity got significantly reduced. Vertical turbulent density flux was of secondary importance for formation of the anticyclonic cap over the summit.

Distribution and habitat association of benthic fish on the Condor seamount (NE Atlantic, Azores) from in situ observations

Distribution of fish assemblages and habitat associations of demersal fishes on the Condor seamount were investigated by analyzing in situ video imagery acquired by the Remotely-Operated Vehicles ROV SP300 and Luso 6000. A total of 51 fish taxa from 32 families were inventoried. Zooplanktivores (10 species) were the most abundant group followed by carnivores (23 species) and benthivores (18 species). Non-metric multidimensional scaling (MDS) analyses were performed on dive segments to visualize the spatial relationships between species and habitat type, substrate type or depth, with depth being the most significant parameter influencing fish distribution. Four major fish groups were identified from their vertical distribution alone: summit species (generally to <300m depth); broad ranging species (ca. from 200 to 800m); intermediate ranging slope species (ca. from 400m to 800–850m); and deeper species (800–850–1100m). The fish fauna observed at the summit is more abundant (15.2fish/100m2) and habitat-specialized than the fish observed along the seamount slope. Down the seamount slope, the summit fish assemblage is gradually replaced as depth increases, with an overall reduction in abundance. On the summit, three species (Callanthias ruber, Anthias anthias and Lappanella fasciata) had higher affinity to coral habitats compared to non-coral habitats. A coherent specialized fish assemblage associated to coral habitats could not be identified, because most species were observed also in non-coral areas. On the seamount's slope (300–1100m), no relationship between fish and coral habitats could be identified, although these might occur at larger scales. This study shows that in situ video imagery complements traditional fishing surveys, by providing information on unknown or rarely seen species, being fundamental for the development of more comprehensive ecosystem-based management towards a sustainable use of the marine environment.

Condor seamount (Azores, NE Atlantic): A morpho-tectonic interpretation

High-resolution datasets collected by multibeam and acoustic backscatter surveys were used to produce fine-scale seafloor nature and morpho-tectonic interpretations of the Condor seamount. Condor constitutes an elongated volcanic ridge that extends for 39km and rises more than 1800m from the surrounding seafloor. Constructive morphologies include (i) linear eruptive centres, (ii) volcanic cones with or without summit depressions, (iii) lava flows and (iv) hummocky sectors. Eruptive type is interpreted to vary with depth. On the deeper seamount extremities, the predominance of highly acoustically backscattering volcanic cones and hummocky terrain is interpreted to result from effusive eruptions not yet covered by sediment deposits. In contrast, the smoother relief of the central seamount flanks is interpreted as draping and infilling of the underlying effusive relief by (i) primary volcaniclastic deposits produced by explosive eruptions on the shallowest parts of the ridge, together with (ii) secondary volcanigenic sediments resulting from truncation of the seamount top by swell erosion and (iii) sediments resulting from biogenic production.A set of WNW–ESE to NW–SE trending volcano-tectonic structures are shown to control most of the fissural volcanism that formed the ridge. A network of NNW–SSE trending faults is identified on the sea-floor around Condor but they show little relation with the distribution of volcanic edifices or with post-emplacement dismantling of the seamount. These fault sets are related to the transtensional regime acting on the Azorean segment of the Eurasia–Nubia plate boundary.Erosional features include (i) palaeo wave-cut platforms on the seamount summit, (ii) landslide scars produced by lateral collapses of the NE and SW-facing flanks, (iii) gullies and turbidity current channels and (iv) mass-wasting deposits. Iceberg drag and bump marks are also identified on the seamount upper flanks, representing the first reference to such features in the Azores and an additional low latitude record.Given the lack of major erosional and tectonic dismantling, Condor is suggested to be a relatively young seamount. A revised factoring of eustatic, erosional and isostatic processes does not exclude that the summit may have been eroded as late as the Last Glacial Maximum.

Spatial and temporal variability of demersal fishes at Condor seamount (Northeast Atlantic)

Temporal and spatial patterns of variation of benthic and benthopelagic fish assemblages on the Condor Seamount of the Azores, Northeast Atlantic, were studied based on longline samples from the depth interval 200–1300m depth. The seamount was used as a commercial fishing ground for decades but is currently closed to fishing as a temporary protected area for research. The protection regime offers an opportunity to monitor and analyze responses to harvesting and recovery from previous fishing impacts. Species number, catches per unit of effort, and zonation with depth corresponded in general with what was observed elsewhere for the Azorean demersal fish community. Total abundance, species richness and species composition significantly varied in time and space within the seamount, generally showing a North–South asymmetry. Abundance and species richness were higher in the Northern than in the Southern sector of the seamount, mainly due to higher abundances of the species Helicolenus dactylopterus, Pagellus bogaraveo, Beryx splendens and Trachurus picturatus. Analyses of abundance variation of the most frequent species showed an array of species-specific responses. The variability of fish assemblages is discussed in the light of oceanographic and anthropogenic factors, which may drive the observed patterns and trends.

Organic matter composition and macrofaunal diversity in sediments of the Condor Seamount (Azores, NE Atlantic)

In recent years increasing knowledge has been accumulated on seamounts ecology; however their sedimentary environments and associated biological communities remain largely understudied. In this study we investigated quantity and biochemical composition of organic matter and macrofaunal diversity in sediments of the Condor Seamount (NE Atlantic, Azores). In order to test the effect of the seamount on organic matter distribution, sediment samples were collected in 6 areas: the summit, the northern and southern flanks and bases, and in an external far field site. Macrofauna abundance and diversity were investigated on the summit, the southern flank and in the far field site. The organic matter distribution reflected the complex hydrodynamic conditions occurring on the Condor. Concentrations of organic matter compounds were generally lower on the whole seamount than in the far field site and on the seamount summit compared to flanks and bases. A clear difference was also evident between the northern and southern slopes of the Condor, suggesting a role of the seamount in conditioning sedimentation processes and distribution of food resources for benthic consumers. Macrofauna assemblages changed significantly among the three sampling sites. High abundance and dominance, accompanied by low biodiversity, characterized the macrofauna community on the Condor summit, while low dominance and high biodiversity were observed at the flank. Our results, although limited to five samples on the seamount and two off the seamount, do not necessarily support the paradigm that seamounts are more biodiverse than the surrounding seafloor. However, the abundance (and biomass), functional diversity and taxonomical distinctiveness of the macrofaunal assemblages from the Condor Seamount suggest that seamounts habitats may play a relevant role in adding to the regional biodiversity.

Cestodes from deep-water squaliform sharks in the Azores

The majority of our knowledge on marine tapeworms (cestodes) is limited to taxa that are relatively easy to obtain (i.e., those that parasitize shallower-water species). The invitation to participate in a deep-water research survey off the Condor seamount in the Azores offered the opportunity to gain information regarding parasites of the less often studied sharks of the mesopelagic and bathypelagic zone. All tapeworms (Platyhelminthes: Cestoda) found parasitizing the spiral intestine of squaliform shark species (Elasmobranchii: Squaliformes) encountered as part of this survey, as well as some additional Azorean sampling from previous years obtained from local fishermen are reported. In total, 112 shark specimens of 12 species of squaliform sharks representing 4 different families from depths ranging between 400 and 1290m were examined. Cestodes were found in the spiral intestines from 11 of the 12 squaliform species examined: Deania calcea, D. cf. profundorum, D. profundorum, Etmopterus princeps, E. pusillus, E. spinax, Centroscyllium fabricii, Centroscymnus coelolepis, C. cryptacanthus, C. crepidater, and Dalatias licha. No cestodes were found in the spiral intestines of Centrophorus squamosus. Light microscopy and scanning electron microscopy revealed several potentially novel trypanorhynch and biloculated tetraphyllidean species. Aporhynchid and gilquiniid trypanorhynchs dominated the adult cestode fauna of Etmopterus and Deania host species, respectively, while larval phyllobothriids were found across several host genera, including, Deania, Centroscyllium, and Centroscymnus. These results corroborate previous findings that deep-water cestode faunas are relatively depauperate and consist primarily of trypanorhynchs of the families Gilquiniidae and Aporhynchidae and larval tetraphyllideans. A subset of specimens of most cestode species was preserved in ethanol for future molecular analysis to allow more definitive determinations of the identification of the larval tetraphyllideans and trypanorhynchs lacking evaginated tentacles and other key diagnostic features.

Meiofauna assemblages of the Condor Seamount (North-East Atlantic Ocean) and adjacent deep-sea sediments

Seamounts are currently considered hotspots of biodiversity and biomass for macro- and megabenthic taxa, but knowledge of meiofauna is still limited. Studies have revealed the existence of highly diverse meiofauna assemblages; however most data are mainly qualitative or focused only on specific groups, thus preventing comparisons among seamounts and with other deep-sea areas. This study, conducted on Condor Seamount (Azores, North-East Atlantic Ocean), describes variation in abundance, biomass, community structure and biodiversity of benthic meiofauna from five sites located on the Condor Seamount: and one site away from the seamount. While the summit of the seamount hosted the highest alpha biodiversity, the flanks and the bases showed a rich meiofauna assemblage in terms of abundance and biomass. The observed marked differences in grain size composition of sediments reflected the oceanographic conditions impacting different sectors of the Condor seamount, and could play an important role in the spatial distribution of different meiofaunal taxa. Trophic conditions (biochemical composition of organic matter) explained 78% of the variability in the meiofauna biomass pattern while sediment grain influenced the vertical distribution of meiofauna and only partially explained meiofaunal taxa composition. This study provides a further advancement in the knowledge of meiofaunal communities of seamounts. Only a deeper understanding of the whole benthic communities (including meiofauna) will allow to elaborate effective management and conservation tools for seamount ecosystems.

Variability of zooplankton communities at Condor seamount and surrounding areas, Azores (NE Atlantic)

Seamounts are common topographic features around the Azores archipelago (NE Atlantic). Recently there has been increasing research effort devoted to the ecology of these ecosystems. In the Azores, the mesozooplankon is poorly studied, particularly in relation to these seafloor elevations. In this study, zooplankton communities in the Condor seamount area (Azores) were investigated during March, July and September 2010. Samples were taken during both day and night with a Bongo net of 200µm mesh that towed obliquely within the first 100m of the water column. Total abundance, biomass and chlorophyll a concentrations did not vary with sampling site or within the diel cycle but significant seasonal variation was observed. Moreover, zooplankton community composition showed the same strong seasonal pattern regardless of spatial or daily variability. Despite seasonal differences, the zooplankton community structure remained similar for the duration of this study. Seasonal variability better explained our results than mesoscale spatial variability. Spatial homogeneity is probably related with island proximity and local dynamics over Condor seamount. Zooplankton literature for the region is sparse, therefore a short review of the most important zooplankton studies from the Azores is also presented.

Quantifying the direct use value of Condor seamount

Seamounts often satisfy numerous uses and interests. Multiple uses can generate multiple benefits but also conflicts and impacts, calling, therefore, for integrated and sustainable management. To assist in developing comprehensive management strategies, policymakers recognise the need to include measures of socioeconomic analysis alongside ecological data so that practical compromises can be made. This study assessed the direct output impact (DOI) of the relevant marine activities operating at Condor seamount (Azores, central northeast Atlantic) as proxies of the direct use values provided by the resource system. Results demonstrated that Condor seamount supported a wide range of uses yielding distinct economic outputs. Demersal fisheries, scientific research and shark diving were the top-three activities generating the highest revenues, while tuna fisheries, whale watching and scuba-diving had marginal economic significance. Results also indicated that the economic importance of non-extractive uses of Condor is considerable, highlighting the importance of these uses as alternative income-generating opportunities for local communities. It is hoped that quantifying the direct use values provided by Condor seamount will contribute to the decision making process towards its long-term conservation and sustainable use.

Phytoplankton variability and oceanographic conditions at Condor seamount, Azores (NE Atlantic)

The variability of phytoplankton biomass (chlorophyll a as a proxy of biomass) and community structure was evaluated over and around the Condor seamount SW of Faial Island in the Azores Archipelago using data provided from five cruises (July and November 2009, and March, July and October 2010). Phytoplankton cell abundance, taxonomy and chlorophyll a concentration were related to both the physical–chemical conditions and to the main circulation patterns observed, bringing new insights into the temporal and spatial variability of phytoplankton. Only microphytoplankton and large nanophytoplankton were identified. Higher phytoplankton abundances were observed during 2010 with a maximum in October (1.3×105cells.L−1), and higher biomasses were reported at sub-surface in March (0.43mg Chl-a.m−3). Diatoms were the dominant group (e.g., Pseudo-nitzschia spp. and Chaetoceros spp.) except in November 2009 when coccolithophores dominated (e.g., Ophiaster spp.). Significant differences were found between seasons but not in space, and salinity appears to be an important factor contributing for this seasonal variation. The present study also provides, for the first time, a list of phytoplankton species for this seamount.

Reconstruction of demersal fisheries history on the Condor seamount, Azores archipelago (Northeast Atlantic)

Commercial fishing data were analyzed in order to reconstruct the history of the demersal fishery on Condor seamount, a temporarily protected area in the Northeast Atlantic (Azores). Considering the eight commercially most important demersal fish species, estimates for the period 1993–2009 revealed that on average landings from this area represented 2% of the annual landings by weight of these species in the Azores. Over this period the average estimated volume of the Condor landings was 71t/year, with the blackspot seabream (Pagellus bogaraveo) and the wreckfish (Polyprion americanus) representing about 54% of the landings, and the average value was €346 thousand per year. Annual trends of landings and of landings per unit effort suggest species-specific abundance responses to fishing, but most of the exploited species may have been significantly reduced at the Condor seamount. The proportion of large specimens may have declined in some of the studied species. Results suggest that artisanal fisheries are capable of causing important reductions in abundance levels of demersal species living on seamounts. Species life history characteristics, their degree of residency, and dependence on outside source areas may be important determinants for the status and the time scales required for recovery to previous abundances of the species. With the current Condor seamount fishing moratorium, exploitation rate has been reduced to zero and this is a unique opportunity to study the responses of the different previously exploited species to the reduced fishing mortality. New understanding may benefit seamount fisheries management in the region.