Bottom Communities Research Articles

ROVvstrawling approaches in the study of benthic communities: the case ofPennatula rubra(Cnidaria: Pennatulacea)

Megabenthic soft bottom communities of trawlable grounds have been studied since the first few decades of the last century, thanks to trawl fishing technologies. Despite providing an extensive amount of presence data, trawling cannot be considered reliable from a quantitative point of view, frequently giving only weak information about sessile species density, large and small-scale distribution and main habitat features. The recent development of visual technologies on remotely operated vehicles (ROVs) can give a more accurate approach for the study of mega-epibenthic communities. The present study reports the application of both ROV imaging and trawling approaches for the study of a large aggregation (i.e. field) of the red sea penPennatula rubrain the Ionian Sea. Density, biomass and population structure were studied in the same population ofP. rubra. The density assessed by ROV was significantly higher than that estimated with a three-year series of trawling surveys. Trawling gear efficiency in the removal ofP. rubrawas low overall. Incidental mortality can be very high due to damage to those specimens that encounter the trawl net but are not directly captured. However, sampling of several colonies by trawling was necessary to establish biometric correlations to estimates of size and biomass from ROV imaging. Trawling catch abundance/biomass data could be useful to identify areas of higher concentration of sea pens, while ROV imaging can be used to monitor these fields in a non-destructive manner that would be consistent with protection measures.

Mechanistic model identifies increasing light availability due to sea ice reductions as cause for increasing macroalgae cover in the Arctic

AbstractIn the Arctic, rising seawater temperatures and increasing underwater light caused by reductions in sea ice cover are expected to change the structure of arctic marine communities. Substantial, sometimes sudden, increases in macroalgal productivity and biomass have already been observed in arctic rocky bottom communities. These macroalgal responses have been attributed to increasing temperature and light, but the relative importance of the suggested drivers of change has not yet been assessed. In this study, we used a mechanistic competition model to unravel the effects of temperature and light on benthic community structure and algae dominance, focusing on key algae species: red calcareous algae and macroalgal fronds. We find that light is the primary driver of increases in macroalgal coverage, whereas increased seawater temperature plays a secondary role. Shifts leading to macroalgae dominated communities may be mediated by competitive interactions, and are likely due to three light‐related processes: earlier sea ice break‐out at high latitudes can result in an exponential increase in the cumulative amount of light that enters the water column during a year; threshold effect in light requirements for algal growth; and light requirements of calcareous algae being substantially lower than those of macroalgae. With continued warming, our modeling results suggest that reduced sea ice coverage and increased light availability will favor dominance of macroalgae, which due to their key ecological role are expected to alter the structure and functioning of arctic rocky bottom ecosystems.

Similarity and difference of bioenergy characteristics of polychaetes in bottom communities in the shallow gulfs of the Arctic and Antarctic

Comparison of energetic fl ow through bottom communities (on the example of polychaete populations) in the shallow bights the Chaun Bay (East Arctic) and the Fjord Nella (East Antarctic) located in high latitudes of opposite hemispheres of the planet is carried out for the fi rst time. Polychaete worms abundantly and diversely represented in the bottom biocenosis and playing an important role in their life are one of the most suitable for this kind of analysis of the group. The material is collected and processed by common methods. It turned out that the average values of biomass and assimilation are comparable, although their indices are somewhat higher in Chaun Bay than in Nella Fjord, so the mean values of the current energy are 56 ± 25 and 40 ± 13 kcal / m2 per year, respectively. In this case, such similarity is mainly due to the duration of the light time due to the location of the bays on similar geographical latitudes. In both cases, it was noted that at lower depths, lower values of the energy fl ux are inherent in different sections of the gulf, due to freshening and abrasion of the ice, and higher — at great depths, where the conditions are more stable. It has been established that in the Chaun Bay the share of the biomass of suspension feeders is higher on hard bottom in the macrophyte belt, and on the muds occupying the largest areas of the bottom, deposit feeders predominate. In the Nella Fjord, on the contrary, large areas of the bottom are represented by hard substratum and are occupied, respectively, prevalence of suspension feeders, whereas non-large areas with a slight glossiness are used for life in small forms of infauna and which, according to the type of food, refer to deposit feeders. One of the distinguishing features of the assimilation in the considered bays is the tendency of its growth with depth in the Chaun Bay and its relative constancy in the Nella Fjord; the other is the achievement of relatively high values of the energy fl ux in some parts of the shallow Arctic compared with Antarctica. The differences are apparently explained by the complexity and variability of the water regime in the Chaun Bay and by the greater silting of the bottom, compared to the relatively constant natural conditions of the Nella Fjord, which together determine the features of the functioning of populations of polychaetes, as well as other groups of inhabitants.The bioenergetic characteristics of bottom communities in the shallow bays of the Arctic and Antarctic have both differences and similarities, and, on the whole, depend on the physico-chemical originality of the areas.

Impact of mining on macroinvertebrate species richness in mountain streams

Mining is a major source of environmental degradation in mountains. To assess the negative impact of mining on aquatic ecosystems, the bottom communities of a small mountain Breksа river (South-Western Altai), which receives drainage water from the mining enterprises, were investigated. Macroinvertebrate samples were taken monthly from April to October 2005-2010 at the background site and the impact zone of Breksa river. A significant decrease in macroinvertebrate species richness was found in the impact zone as compared to the background site. Each sample upstream from the impact zone contained 18±1.5 macroinvertebrate species, while downstream – only 6.5±0.6 species. The species richness correlated negatively with the content of suspended substances in water (r=-0.32) and the concentration of heavy metals (r=-0.69). Changes in the composition of the most frequent species caused by pollution are revealed. The most sensitive and resistant to pollution macroinvertebrates are presented. The most sensitive to pollution are mayflies Epeorus pellucidus, Neoleptophlebia chocolatа, caddisflies Hydropsyche newae, Brachycentrus americanus, Dicosmoecus palatus, Glossosoma altaicum, and crustaceans Gammarus korbuensis. The most resistant are chironomids larvae. The data obtained prove the necessity of regional modifications of widespread European methods of water quality bioindication.

Seasonal diversity and composition of epibenthic organisms on a North Carolina, USA continental shelf hard bottom

Subtidal marine hard bottoms are valuable habitats that support diverse epibenthic and fish communities. The degree to which hard bottom community structure varies spatially and temporally is not fully understood. Identifications of macroalgae and sessile invertebrates in scraped quadrats were done at three separate times (May, July, and September 2016) at three sites along the 5-mile ledge hard bottom in Onslow Bay, North Carolina. Spatial and temporal epibenthic community diversity and composition were measured. Diversity did not vary over time (p=0.065) or between sampling sites (p=0.130). There was, however, a change in community composition over time (p <0.003) and between two of the studied sites (p=0.012). Bottom water temperature might partially explain the observed temporal variation in composition, and site wide patchiness might explain the spatial variation in composition. These findings indicate that seasonal sampling of multiple sites is required to establish community baselines for these valuable habitats.

MACROZOOBENTHIC COMMUNITIES IN THE EASTERN PART OF THE EASTERN BOSPHORUS STRAIT (PETER THE GREAT BAY, JAPAN SEA)

In total, 146 species of macrozoobenthos belonged to 11 taxonomic groups are found in the surveyed area in the eastern part of the Eastern Bosphorus Strait. Polychaetes have the highest species number, followed by bivalves and amphipods with five times less number of species. Polychaetes and bivalves have the highest occurrence, too, gastropods and amphipods occur frequently, as well. Bivalves dominate by biomass, but polychaetes — by their abundance. Benthos of the Patrokl Bight at the northern coast is poor relatively to the southern part of the strait at Russky Island because of low species diversity of amphipods, gastropods and decapods. Four macrozoobenthic communities are defined with the following titular species: Acila insignis + Scalibregma inflatum, Ophiura sarsi + Scoloplos armiger, Ennucula tenuis + Nicolea sp., and Dipolydora cardalia + (Melinna elisabethae or Maldane sarsi). Besides, Echinocardium cordatum dominates at the single station in the internal Patrokl Bight and Protocallithaca adamsi dominates at the single station in the Zhitkov Inlet. Majority of these communities are quite diverse and abundant. All of them, except the last case, are undisturbed or slightly disturbed and possess in good or moderate ecological state. In the case of the Zhitkov Inlet, the impoverished community of P. adamsi is considerably disturbed due to anthropogenic impact. Differentiation between the majority of communities is noted along gradients of natural environmental factors, as depth and fractional composition of bottom sediments. All conclusions are statistically significant and based on the results of consequential use of the factor and cluster analysis, non-metric multidimensional scaling and constrained correspondence analysis with bootstrap and randomization procedures. There is noted that the bottom communities in this area are subjected to rather significant contamination that supposedly causes decreasing of their stability and they may change their species composition and abundance under additional negative impact.

Plankton and Bottom Communities in the Saline Rivers of Lake Elton Basin: Statistical Analysis of Dependences

Hydrological, hydrochemical, and hydrobiological data for five saline rivers of the arid Lake Elton region were analyzed. We found that interactions between plankton and benthic communities, in particular, between macrozoobenthos, meiobenthos and zooplankton, created mixed ecological groups of species. Abundances of plankton and bottom communities significantly correlated, which indicated that there is a close relationship between them due to biotic interactions and their similar responses to the effects of environmental factors. Multidimensional scaling and cluster analyses, the construction of hierarchical trees and species diversity models, the spatial correlation Mantel test, etc., were used to study the structure of communities in strongly disbalanced ecosystems of highly mineralized rivers. Indicator species were established by the TWINSPAN procedure. Our results demonstrated that plankton and bottom communities of the saline rivers can be represented as specific consortia or structural units of the river ecosystems.

Nematodes in Meiobenthos and Periphyton of the Rybinsk Reservoir (Review)

This paper presents data on changes in the taxonomic composition and abundance of nematodes in meiobenthos and periphyton of the Rybinsk Reservoir in the long term. The species composition of roundworms in bottom communities is significantly richer and their number is manyfold higher than among fouling organisms. These differences are determined by the different habitat conditions at the bottom and hard substrate surfaces in the water column. In modern anthropogenically disturbed zones of various waterbodies, the biocenotic and functional roles of nematodes depend to a larger extent on food availability than on some other environmental factors limiting the development of worms. Roundworms, living under a wide range of ecological conditions, are one of the key groups of invertebrates critical for preserving aquatic life under anthropogenic stresses.

Heteromysis cocoensis n. sp. (Crustacea: Mysida: Mysidae) from coastal waters of Isla del Coco, Costa Rica

ABSTRACT A survey of the invertebrate fauna of coral reef hard bottom communities in the shallow waters of Isla del Coco yielded a new species of mysid belonging to the genus Heteromysis S. I. Smith, 1873. Heteromysis (Olivemysis) cocoensis, n. sp. was collected from coral rubble at depths of 8 to 34 m. It differs from its congeners by having male pleopods 1, 3, and 4 with modified setae. Within the subgenus Olivemysis Bacescu, 1968, the new species is morphologically most similar to Heteromysis. ekamako Wittmann and Chevaldonne, 2017 from the Pacific, Heteromysis. gomezi Bacescu, 1970, H. mayana Brattegard, 1970, and H. rubrocinta, Bacescu, 1968 from the Western Atlantic, and Heteromysis. dardani Wittmann, 2008, Heteromysis. wirtzi Wittmann, 2008, and Heteromysis. sabelliphila Wittmann and Wirtz, 2017 from the Eastern Atlantic. However, H. cocoensis n. sp. is distinguished from these six apparently closely related species by the following combination of characters: flagellate, modified setae on articles 1 and 3 of the antennular peduncle, and setation of thoracic endopod 3, male pleopods 1, 3 and 4, uropodal endopods, and the apical and lateral margins of the telson. A diagnostic table separating these eight species is given.

The implementation of Marine Stewardship Council (MSC) certification in Russia: Achievements and considerations

The Marine Stewardship Council (MSC) certification program in Russia is now well established and, in addition to fishery clients and stakeholders, involves environmental NGOs and experts familiar with the local management system. The present study aims to analyze the current status of the program and constitutes the first study covering all Russian MSC certifications. Based on certification reports and twenty semi-structured interviews with stakeholders, it was shown that problems with certification vary among fisheries. The most advanced in terms of management are the Barents Sea codfish fisheries, which are co-managed by Russia and Norway. The main concern of these fisheries is the use of bottom trawls, which may seriously affect bottom communities. The Alaska pollock fishery in the Sea of Okhotsk experienced serious pressure from rival fisheries during the certification process. In the Far East, interviewees dealing with the salmon fisheries note a high level of illegal, unreported and unregulated (IUU) fishing and insufficient scientific data for comprehensive stock assessment. For small-scale inland perch fisheries from the central part of the country, recreational and illegal fishing are important problems that are difficult to quantify. Many interviewees repeatedly mentioned communication issues, difficulties with access to scientific and management information, and the overall complexity of the MSC certification process. The study shows that important preconditions to expanding certification are making the process manageable for export-oriented companies and developing a national market for sustainable seafood.

Microalgal community structure and primary production in Arctic and Antarctic sea ice: A synthesis

Sea ice is one the largest biomes on earth, yet it is poorly described by biogeochemical and climate models. In this paper, published and unpublished data on sympagic (ice-associated) algal biodiversity and productivity have been compiled from more than 300 sea-ice cores and organized into a systematic framework. Significant patterns in microalgal community structure emerged from this framework. Autotrophic flagellates characterize surface communities, interior communities consist of mixed microalgal populations and pennate diatoms dominate bottom communities. There is overlap between landfast and pack-ice communities, which supports the hypothesis that sympagic microalgae originate from the pelagic environment. Distribution in the Arctic is sometimes quite different compared to the Antarctic. This difference may be related to the time of sampling or lack of dedicated studies. Seasonality has a significant impact on species distribution, with a potentially greater role for flagellates and centric diatoms in early spring. The role of sea-ice algae in seeding pelagic blooms remains uncertain. Photosynthesis in sea ice is mainly controlled by environmental factors on a small scale and therefore cannot be linked to specific ice types. Overall, sea-ice communities show a high capacity for photoacclimation but low maximum productivity compared to pelagic phytoplankton. Low carbon assimilation rates probably result from adaptation to extreme conditions of reduced light and temperature in winter. We hypothesize that in the near future, bottom communities will develop earlier in the season and develop more biomass over a shorter period of time as light penetration increases due to the thinning of sea ice. The Arctic is already witnessing changes. The shift forward in time of the algal bloom can result in a mismatch in trophic relations, but the biogeochemical consequences are still hard to predict. With this paper we provide a number of parameters required to improve the reliability of sea-ice biogeochemical models.

Variations in the Carbon and Nitrogen Isotope Composition of the Crabs Chionoecetes opilio (Fabricius, 1788) and Hyas coarctatus Leach, 1816 (Crustacea: Decapoda) from the Chukchi Sea

Some regions of the Chukchi Sea shelf are characterized by an unusually high abundance of the benthos. The carbon and nitrogen isotope composition (δ13C and δ15N) of two crab species, Chionoecetes opilio and Hyas coarctatus, which occupy the upper trophic levels in bottom communities in the southern regions influenced by the Anadyr Water (AW) and in the regions exposed to the influence of the Siberian Coastal Current (SCC), was analyzed in order to compare between the trophic characteristics of their benthic communities. It has been found that these two species have similar spatial trends of stable isotope signature variations. As the effect of the productive AW on bottom communities decreases, a substantial depletion of δ13C with a simultaneous growth of δ15N values are observed in crab tissues. The trophic niches of C. opilio and H. coarctatus, which are represented by “isotope” niches as standard ellipse areas in the δ13C/δ15N biplot, significantly overlap in communities of the southern part of the shelf and become completely separated in those of the regions influenced by the SCC. The separation of the isotope niches of C. opilio and H. coarctatus and the simultaneous increase in δ15N values in both species by more than 3‰ indicate partitioning of the trophic resources between them and elongation of the food chains of both these carnivorous generalists by almost one trophic level in the communities that exist under the influence of less productive waters.

Soft Bottom Communities in Marine Lakes Sisjajarvi and Linjalampi (Barents Sea).

Based on the data of benthic surveys of 2010-2012, three benthic communities: a shallow-water community with the dominance of Scoloplos spp., Nucula tennuis, and Scalibregma inflatum; a deep-water community with the dominance of Chaetosone sp.; and a community of mixed sediments, have been distinguished in soft sediments in marine lakes Sisjajarvi and Linjalampi. These communities are typically marine and similar to other communities in shallow areas of the Barents Sea. They mostly differ in a high abundance of the polychaete Scalibregma inflatum and a small number of echinoderms from the communities in other bays of the Barents Sea. The abundance of the polychaete S. inflatum indicates indirectly possible cases of anoxia in Lake Sisjajarvi.

Особенности количественного распределения рыб и десятиногих ракообразных в дельте реки Меконг в меженный период 2018 г.

Впервые изучены особенности количественного распределения рыб и десятиногих ракообразных донно-придонного сообщества гидробионтов в нижней части дельты р. Меконг — в шести основных протоках р. Тиен и в прилегающей к их устьям прибрежной морской зоне. Сбор материала осуществлялся в меженный период с апреля по июнь 2018 г. стандартным промысловым бимтралом от предустьевой морской зоны вверх по течению проток на расстояние до 110 км. Средняя масса улова — около 30 кг, максимальная — 100 и более кг, однако средний уровень вылова рыб и ракообразных составлял 1,5 кг, наибольший — 4 кг, а остальная часть приходилась на мусор и остатки растительности. Для сравнительного анализа пространственной изменчивости обилия рыб и десятиногих ракообразных на 36 станциях вычислены средние удельные показатели численности и биомассы по результатам 102 тралений. Установлены весьма широкие пределы вариаций количественных показателей. Так, удельная численность рыб колебалась от 23,4 до 1978,2 (в среднем — 333,3) экз.·га-1, десятиногих ракообразных — от 10,6 до 5091,5 (358,1) экз.·га-1, биомасса этих групп гидробионтов составляла 219,1–22773,5 (1969,9) г·га-1 и 31,4–9337,1 (740,6) г·га-1 соответственно. Выявлены основные закономерности пространственного распределения плотности гидробионтов. Отмечено увеличение средней удельной численности рыб в верхней части исследованных водотоков до 656,2 экз.·га-1, что вдвое превышает показатель в целом по дельте, при относительно равномерном распределении средней удельной биомассы, связанном с присутствием молоди массовых промысловых видов и мелкоразмерных рыб. Тренды пространственного распределения численности и биомассы десятиногих ракообразных весьма близки; наибольшие их показатели зарегистрированы в устьях рек и в приустьевой морской зоне дельты за счёт появления в составе сообществ креветок подотряда Dendrobrachiata (пенеидные креветки) и представителей подотряда Pleocyemata (крабы). Среди рыб в меженный период доминировали представители морских по происхождению семейств: пальцепёрые (Polynemidae), ариевые сомы (Ariidae) и анчоусовые (Engraulidae), доля которых в общем вылове по относительной численности составляла 39,4, 20,4 и 13,4 % соответственно, по биомассе — 28,5, 34,9 и 9,2 %, преимущественно за счёт эвригалинных эстуарных и прибрежных (шельфовых) видов. Среди десятиногих ракообразных преобладали морские креветки (семейства Penaeidae и Aristeidae) и пресноводные (семейство Palaemonidae). Представители семейства карповых (Cyprinidae) (одного из наиболее богатых по разнообразию, численности и биомассе в дельте р. Меконг), равно как и представители ряда других семейств пресноводных рыб, за исключением акизовых сомов (Akysidae), не характеризовались обилием, что связано с их миграциями в сухой сезон вверх по течению реки. Проанализировано влияние некоторых антропогенных факторов на количественные показатели донно-придонных сообществ. Одной из причин довольно низких средних значений плотности рыб и десятиногих ракообразных могут быть высокие концентрации твёрдых бытовых и промышленных отходов, особенно в районах населённых пунктов: это может оказывать негативное влияние на питание и нагул, а также на жизненные циклы данных гидробионтов в целом. Отмечены аномалии связей между показателями распределения солёности воды, удельной плотности рыб и ракообразных в районе плотины на р. Балай. Выше по течению от плотины вода пресная, ниже — солёная (соответствующий показатель придонного слоя достигает 17 ‰), при этом более высокие значения средней удельной численности рыб отмечены у нижнего бьефа плотины, а средней удельной биомассы — у верхнего. Здесь отмечены низкие средние удельные значения численности и биомассы десятиногих ракообразных, что связано, возможно, с прекращением нерестовых миграций представителей семейств как морских, так и пресноводных креветок. Полученные результаты могут быть использованы как базовые для последующего мониторинга изменения структурных характеристик придонных сообществ рыб и десятиногих ракообразных дельты р. Меконг.

Taxonomic diversity of benthic invertebrates of the Moskva River in the Moscow area: diversity and distribution

&lt;p&gt;Biological diversity and distribution of benthic invertebrates in the Moskva River within the frames of Moscow are studied. Totally, 72 invertebrate taxa were found including 8 invasive species with amphipod &lt;em&gt;Gmelinoides fasciatus &lt;/em&gt;(Stebbing, 1899), an invader from the Lake Baikal. A number of observed species are characterized with high abundance and biomass while most of observed taxa are represented by a small number of individuals. The greatest species diversity was revealed for insect larvae, mainly due to Chironomidae. The main species on the investigated section of the river are various crustaceans, mainly amphipods and decapods (when present in samples) showing more than 70-90% of all biomass of zoobenthos at all stations (sites). Multivariate cluster analysis allowed concluding that bottom communities in Moskva River, the degree of their quantitative development, species richness and diversity are mainly influenced by the structure of bottom substrates rather than other factors. The most diverse benthic communities are presented on silty bottom with mixture of shells of mollusks and plant remains. The lowest diversity of benthic communities is characteristic for sites with relatively strong water and well washed sand as the main bottom substrate. Obtained data starts annual monitoring of the river at indicated stations using biological indicators, namely native amphipod &lt;em&gt;Gammarus lacustris&lt;/em&gt; and invasive &lt;em&gt;G. fasciatus&lt;/em&gt;.&lt;/p&gt;

Особенности пространственного распределения донных сообществ равнинной реки бассейна Средней Волги

Особенности пространственного распределения донных сообществ равнинной реки бассейна Средней Волги

Reviews and syntheses: Ice acidification, the effects of ocean acidification on sea ice microbial communities

Abstract. Sea ice algae, like some coastal and estuarine phytoplankton, are naturally exposed to a wider range of pH and CO2 concentrations than those in open marine seas. While climate change and ocean acidification (OA) will impact pelagic communities, their effects on sea ice microbial communities remain unclear. Sea ice contains several distinct microbial communities, which are exposed to differing environmental conditions depending on their depth within the ice. Bottom communities mostly experience relatively benign bulk ocean properties, while interior brine and surface (infiltration) communities experience much greater extremes. Most OA studies have examined the impacts on single sea ice algae species in culture. Although some studies examined the effects of OA alone, most examined the effects of OA and either light, nutrients or temperature. With few exceptions, increased CO2 concentration caused either no change or an increase in growth and/or photosynthesis. In situ studies on brine and surface algae also demonstrated a wide tolerance to increased and decreased pH and showed increased growth at higher CO2 concentrations. The short time period of most experiments (&lt; 10 days), together with limited genetic diversity (i.e. use of only a single strain), however, has been identified as a limitation to a broader interpretation of the results. While there have been few studies on the effects of OA on the growth of marine bacterial communities in general, impacts appear to be minimal. In sea ice also, the few reports available suggest no negative impacts on bacterial growth or community richness. Sea ice ecosystems are ephemeral, melting and re-forming each year. Thus, for some part of each year organisms inhabiting the ice must also survive outside of the ice, either as part of the phytoplankton or as resting spores on the bottom. During these times, they will be exposed to the full range of co-stressors that pelagic organisms experience. Their ability to continue to make a major contribution to sea ice productivity will depend not only on their ability to survive in the ice but also on their ability to survive the increasing seawater temperatures, changing distribution of nutrients and declining pH forecast for the water column over the next centuries.

Alien species of amphipods (Amphipoda, Gammaridea) in the bottom communities of the Kuybyshev and Saratov reservoirs: Features of distribution and life cycle strategies

Analysis of the composition and distribution of alien species of amphipods and quantitative evaluation of macrozoobenthos communities based on the results of studies of 2009–2012 in the Saratov and Kuybyshev reservoirs is given. It is shown that amphopods Pontogammarus robustoides (Sars, 1894) and Dikerogammarus haemobaphes have the highest invasiveness in comparison with other species in the reservoirs as well as in its tributaries. The features of the life cycle of common amphipod species that contribute to their distribution in the reservoirs of the Middle and Lower Volga are revealed.

Deep-sea benthic habitats modeling and mapping in a NE Atlantic seamount (Galicia Bank)

This study presents the results of seafloor habitat identification and mapping of a NE Atlantic deep seamount. An “assemble first, predict later” approach has been followed to identify and map the benthic habitats of the Galicia Bank (NW Iberian). Biotic patterns inferred from the survey data have been used to drive the definition of benthic assemblages using multivariate tools. Eight assemblages, four hard substrates and four sedimentary ones, have been described from a matrix of structural species. Distribution of these assemblages was correlated with environmental factors (multibeam and backscatter data) using binomial GAMs. Finally, the distribution model of each assemblage was applied to produce continuous maps and pooled in a final map with the distribution of the main benthic habitats. Depth and substrate type are key factors when determining soft bottom communities, whereas rocky habitat distribution is mainly explained by rock slope and orientation. Enrichment by northern water masses (LSW) arriving to GB and possible zooplankton biomass increase at vertical-steep walls by “bottom trapping” can explain the higher diversity of habitat providing filter-feeders at slope rocky breaks. These results concerning vulnerable species and habitats, such as Lophelia and Madrepora communities and black and bamboo coral aggregations were the basis of the Spanish proposal of inclusion within the Natura 2000 network. The aim of the present study was to establish the scientific criteria needed for managing and protecting those environmental values.

Potential Impacts of Everglades Restoration on Lobster and Hard Bottom Communities in the Florida Keys, FL (USA)

The Comprehensive Everglades Restoration Plan (CERP) is intended to restore the Everglades ecosystem (FL, USA) by altering its hydrology, with likely consequences for “downstream” estuarine and marine communities in Florida Bay and the Florida Keys. Spiny lobsters (Panulirus argus) are among several species of special concern with respect to CERP because they are of economic and ecological importance and because their nursery habitat may be impacted. We used agent-based, spatially explicit modeling to evaluate the possible impacts of changing water quality (temperature, salinity, harmful algal blooms (HABs)) on spiny lobsters and sponges, the latter of which provide shelter for juvenile lobsters. In our simulations, lobster abundance declined 6–24% in scenarios where salinity either decreased alone or in combination with HABs that kill sponges and are associated with changing water quality. The most severe decline in lobsters occurred when salinity was lowest and HABs occurred annually. One third of this decline was attributable to decreased salinity that increased lobster mortality and movement. However, the greatest impacts on lobsters were indirect. CERP-associated changes in salinity along with HABs caused a die-off of large sponges, resulting in higher predatory mortality on lobsters that depend on sponges for shelter in hard bottom nursery habitats. Sponges declined by ∼50% in simulations with HABs, whereas decreased salinity alone led to sponge mortality of 9–18%. In contrast, higher temperatures increased juvenile lobster growth and eventual recruitment by approximately 7%. Our results suggest that returning Florida Bay to more estuarine, pre-development conditions is likely to result in an ecosystem reversal that is detrimental to stenohaline marine taxa, a scenario with significant socioeconomic implications.