Wave Exposure

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Assemblages of roving herbivores were consistently different between eastern, warmer, sheltered sites and western, colder, more wave‐exposed sites. At eastern sites, detritivorous‐herbivorous species dominated while omnivores had the highest biomass and were dominant at western sites. Macroalgivores did not show any trends related to location. These distributional patterns, at relatively small spatial scales of a few kilometres, mirror large‐scale latitudinal patterns observed for the studied species along the entire Brazilian coast, where cold water associated species are abundant on south‐eastern rocky reefs (analogous to the western sites of this study), and tropical species are dominant on north‐eastern coral reefs (analogous to the eastern sites). Species‐level analyses demonstrated that depth was an important factor correlated with biomasses of Diplodus argenteus, Sparisoma axillare and Sparisoma tuiupiranga, probably due to resource availability and interspecific competition....

Multiple anthropogenic stressors are causing a global decline in foundation species, including macrophytes, often resulting in the expansion of functionally different, more stressor‐tolerant macrophytes. Previously subdominant species may experience further positive demographic feedback if they are exposed to weaker plant–herbivore interactions, possibly via decreased palatability or being structurally different from the species they are replacing. However, the consequences of the spread of opportunistic macrophytes for the local distribution and life history of herbivores are unknown. The green alga, Caulerpa filiformis, previously a subdominant macrophyte on low intertidal‐shallow subtidal rock shores, is becoming locally more abundant and has spread into warmer waters across the coast of New South Wales, Australia. In this study, we measured (a) the distribution and abundance of a key consumer, the sea urchin Heliocidaris erythrogramma, across a seascape at sites where C. filifor...

Limpets are pivotal for structuring and regulating the ecological balance of littoral communities and are widely collected for human consumption and as fishing bait. Limpets of the species Patella caerulea were collected between April 2016 and April 2017 from two sites, and two samplings per each site with varying degree of exposure to wave action and anthropogenic pressure, in Eastern Mediterranean (Pagasitikos Gulf, Central Greece). This study addresses a knowledge gap on population characteristics of P. caerulea populations in Eastern Mediterranean, assesses population structure, allometric relationships, and reproductive status. Morphometric characteristics exhibited spatio-temporal variation. Population density was significantly higher at the exposed site. Spatial relationship between members of the population exhibited clumped pattern of dispersion during spring. Broadcast spawning of the population occurred during summer. Seven dominant age groups were identified, with the do...

Se dan a conocer nuevos registros de Avicennia bicolor Standl., para México (Pijijiápan, Chiapas). Actualmente, el registro de A. bicolor recolectado por el botánico Eizi Matuda en 1946 en el sistema lagunar Mar Muerto (Paredón, Chiapas) representa el más septentrional en toda su área de distribución. Los resultados presentados en este trabajo, indican que A. bicolor se distri u e e u área li itada pero i porta te e la osta sur del Pa íi o e i a o e rodales relaiva e te de sos o u alto desarrollo estru tural. A te la falta de prote ió a ie tal de la espe ie, se o sidera e esaria su i lusió en la NOM-059 así como el diseño de estrategias de conservación a nivel nacional, regional y local.

Monthly changes of the estuarine fish fauna composition and abundance were investigated in two different habitats in the Ionian Sea. For each month, species richness was measured by the total number of species caught in each station, and the Shannon–Wiener diversity index was calculated. An ordination method (CA) was applied in order to examine the temporal presence of fishes in the studied ecosystems. Eutrophic conditions and type of vegetation influence the settlement and retention of fish in both stations.

The fish diversity of intertidal rock pools in the Glorieuses Islands was investigated using clove-oil anaesthetic. That method, is easy to use and safety is well adapted for this type of census. A total of thirty two species belonging to 14 families were sampled. Of these, 19 were observed as adults in most stations and represented the typical population of these intertidal pools, in particular the Blenniidae that presented the highest species richness and the Gobiidae, which were the most abundant. The 13 remaining species were only observed during their juvenile state and appeared to be only temporary residents. More than half of the species collected (17/32 spp) were not recorded during the previous ichthyofauna study at the Glorieuses islands using UVC, results that show the importance of the anaesthetic method that allows the collection of smaller-sized species that live inside the reef framework and are consequently more difficult to record.

Hydrodynamic forces from breaking waves are among the most important sources of mortality in the rocky intertidal zone. Information about the forces imposed by breaking waves is therefore critical if we are to interpret the mechanical design and physiological performance of wave-swept organisms in an ecologically and evolutionarily relevant context. Wave theory and engineering experiments predict that the process of wave breaking sets a limit on the maximum force to which organisms can be subjected. Unfortunately, the magnitude of this limit has not been determined on rocky shores. To this end, at a moderately exposed shore in central California, we measured the maximum hydrodynamic forces imposed on organism-sized benthic objects and related these forces to nearshore significant wave heights. At 146 of 221 microsites, there was a significant and substantial positive correlation between force and wave height, and at 130 of these microsites, force increased nonlinearly toward a statistically defined limit. The magnitude of this limit varied among sites, from 19 to 730 newtons (N). At 37 other sites, there was no significant correlation between surf zone force and wave height, indicating that increased wave height did not translate into increased force at these sites either. At only 16 sites did force increase in proportion to wave height without an apparent upper bound. These results suggest that for most microsites there is indeed a limiting wave height beyond which force is independent of wave height. The magnitude of the limit varies substantially among microsites, and an index of local topography was found to predict little of this variation. Thus, caution must be exercised in any attempt to relate observed variations in ocean ''waviness'' to the corresponding rates of microsite disturbance in intertidal communities.

Se presentan los resultados obtenidos del estudio de las algas bentónicas de Isla Verde, Veracruz, en aguas del Golfo de México. La lista florística se acompaña de datos sobre la estacionalidad de las especies y su estadio reproductivo, el nivel de marea, el sustrato, la exposición al oleaje y el epifitismo asociado a ellas. Se determinaron 5 especies de Cyanophyceae, 37 de Rhodophyceae, 6 de Phaeophyceae, 8 de Bacillariophyceae y 24 de Chlorophyceae. La flora encontrada en Isla Verde es tropical y típica de los arrecifes coralinos. Se discute la diversidad de las algas con respecto a sustrato, luz y temperatura.

This report describes the working of National Centers for Coastal Ocean Service (NCCOS) Wave Exposure Model (WEMo) capable of predicting the exposure of a site in estuarine and closed water to local wind generated waves. WEMo works in two different modes: the Representative Wave Energy (RWE) mode calculates the exposure using physical parameters like wave energy and wave height, while the Relative Exposure Index (REI) empirically calculates exposure as a unitless index. Detailed working of the model in both modes and their procedures are described along with a few sample runs. WEMo model output in RWE mode (wave height and wave energy) is compared against data collected from wave sensors near Harkers Island, North Carolina for validation purposes. Computed results agreed well with the wave sensors data indicating that WEMo can be an effective tool in predicting local wave energy in closed estuarine environments.

Resumen. El propósito del presente trabajo fue contribuir al conocimiento biológico y pesquero de Chiton articulatus, especie que se captura artesanalmente en las costas de Mazatlán, Sinaloa. Se realizaron recolectas bimestrales en la zona intermareal de las islas Pájaros y Venados, de febrero a diciembre de 2000, durante las mareas más bajas. Las recolectas se realizaron en 4 sitios distintos, 2 en la zona protegida frente a la bahía Mazatlán y 2 en la zona expuesta de ambas islas; los ejemplares se trasladaron al laboratorio para su identifi cación y registro de dimensiones corporales con un vernier (±0.1 mm) y una balanza (± 0.001g). Se analizaron 1 236 organismos, su longitud total (Lt) osciló entre 11.2 y 86.8 mm, su altura (Al) fue de 2.0 a 48.1 mm, su anchura (An) varió de 7.1 mm a 48.1 mm y su peso total (Pt) entre 0.1 y 53.8 g. La mayor parte de la población se distribuyó entre los 31 y 64 mm, con una moda de 41.1 mm y media de 45.6±8.5 mm de Lt. En la zona expuesta de isla Pájaros se presentaron mayores tallas, mientras que las menores se encontraron en la zona protegida de isla Venados; esta diferencia puede explicarse tanto por el grado de exposición al oleaje como por la presión de pesca, que se relaciona con la difi cultad de acceso en cada zona. Las relaciones biométricas entre las tallas fueron de tipo lineal {An=0.5423(Lt)+2.7594, Al=0.2316(Lt)-0.4576 y Al=0.3807(An)-0.3832} y entre talla y peso fueron de tipo potencial {Pt=0.0001(Lt) 2.8404 , Pt=0.0005(An) 2.8807 y Pt=0.0329(Al) 2.3236 }; los valores de la pendiente (b) de las relaciones entre la talla y el peso fueron cercanos a 3, por lo cual se considera que su crecimiento es de tipo isométrico. La relación entre el Pt y el peso del pie (Pp) fue {Pt=4.8778(Pp)+1.0933}. La proporción que se aprovecha de cada individuo es casi del 17 % de su Pt. La captura de C. articulatus es una actividad de subsistencia que diversos grupos realizan de manera temporal o complementaria de otras actividades. No existe ningún tipo de normatividad y/o vigilancia sobre su captura y comercialización. Palabras clave: moluscos, Chiton articulatus, Pacífi co este tropical, islas, distribución de tallas, pesca.

Chondrus crispus Stackhouse alternates between two isomorphic life history phases that differ in cell‐wall phycocolloid composition. It has been long hypothesized that the gametophyte, with strong‐gelling kappa‐type carrageenans, is mechanically superior to the tetrasporophyte, with nongelling lambda‐type carrageenans, which could contribute to the observed gametophytic dominance in many wave‐swept environments. Standard mechanical tests were performed on distal tissues of C. crispus sampled from a range of environments in Narragansett Bay, Rhode Island, using a tensometer equipped with a video extensometer. Life history phase was by far the most important determinant of mechanical properties, whereas environmental factors had only modest influence (vertical distribution) or no effect (exposure); gametophytic distal tissues were 43% stronger, 21% more extensible, and 21% stiffer than tetrasporophytic distal tissues. However, the superior strength of gametophytic tissues was not evid...

Mussels often act as ecosystem engineers in rocky intertidal habitats, favoring the occurrence of many small invertebrates by increasing habitat complexity and improving local environmental conditions. This study tests the hypothesis that invertebrate assemblages from intertidal mussel beds differ between wave-sheltered and wave-exposed habitats. To this aim, we surveyed exposed and sheltered sites spanning 350 km of coastline in Nova Scotia, Canada. We identified all invertebrates and measured their abundance in replicate quadrats that were fully covered by mussels. In total, we found 50 invertebrate taxa living in these mussel beds. Multivariate analyses revealed that the composition of invertebrate assemblages differed significantly between both habitat types. Exposed habitats supported a greater species richness, and the species that mainly explained the compositional difference between both environments were more abundant in exposed ones. Assemblages were taxonomically dominated by arthropods, annelids, and molluscs and numerically dominated by tubificid oligochaetes regardless of exposure. Our results suggest that exposed habitats may favor the occurrence of filterfeeders, such as barnacles, and sheltered habitats the occurrence of predators, such as small crabs and sea stars, in intertidal mussel beds from the NW Atlantic coast.

This study evaluates the biological activity and possible deterrance played by organic crude extracts from six Phaeophyta and two Rhodophyta algae from Southern Caribbean. Bioessays were carried out using concentrations equivalent to those present in algae tissue. Species in general did not show high citotoxic activity. However Dictyota pulchella, showed a delay in the mitotic process for cells stage XVI. Extracts from Dictyota bartayresiana, D. pulchella, Sargassum cymosum and Cladophyllum schnetteri, inhibited S. partitus feeding under laboratory conditions. Nontheless, only extracts from D. bartayresiana and C. schnetteri showed this activity in the field.

Interactions between water motion, primary productivity, and herbivory are complex. Rates of grazing by fish on tropical coral reefs and by sea urchins on temperate rocky reefs are usually high, but can be low in areas of extreme water motion. Some herbivores can switch between mobile (grazing) and sedentary (drift-feeding) behaviours, and this can be influenced by water motion. We compared the relative consumption of the kelp Ecklonia radiata at rocky reefs in western Australia with different wave exposures (inshore versus offshore). No herbivory was recorded offshore, suggesting that wave exposure might inhibit herbivory. We also compared grazing by fish and sea urchins, and grazing versus drift-feeding pathways. Grazing by fish and sea urchins was low, except at one inshore reef where grazing by fish was intense. In contrast, drift-feeding by sea urchins was recorded at all inshore reefs, suggesting that this is a ubiquitous behaviour in the region. We measured productivity of E. radiata to determine if spatial patterns in rates of herbivory matched those of productivity. Productivity of E. radiata was higher on offshore reefs at one location. The observed difference in consumption between inshore and offshore reefs at both locations suggests that consumption is not limited by productivity, but by exposure. Further, the high productivity offshore combined with low rates of herbivory suggest that offshore reefs might be a source of kelp that subsidises other habitats.

Interactions between water motion, primary productivity, and herbivory are complex. Rates of grazing by fish on tropical coral reefs and by sea urchins on temperate rocky reefs are usually high, but can be low in areas of extreme water motion. Some herbivores can switch between mobile (grazing) and sedentary (drift-feeding) behaviours, and this can be influenced by water motion. We compared the relative consumption of the kelp Ecklonia radiata at rocky reefs in western Australia with different wave exposures (inshore versus offshore). No herbivory was recorded offshore, suggesting that wave exposure might inhibit herbivory. We also compared grazing by fish and sea urchins, and grazing versus drift-feeding pathways. Grazing by fish and sea urchins was low, except at one inshore reef where grazing by fish was intense. In contrast, drift-feeding by sea urchins was recorded at all inshore reefs, suggesting that this is a ubiquitous behaviour in the region. We measured productivity of E. radiata to determine if spatial patterns in rates of herbivory matched those of productivity. Productivity of E. radiata was higher on offshore reefs at one location. The observed difference in consumption between inshore and offshore reefs at both locations suggests that consumption is not limited by productivity, but by exposure. Further, the high productivity offshore combined with low rates of herbivory suggest that offshore reefs might be a source of kelp that subsidises other habitats.

Ocean warming poses significant threats to coastal ecosystems. This study investigates the impact of thermal effluents from power plants, as proxies for climate-driven temperatures increase, on Posidonia oceanica meadows and associated fish communities. Using a gradient-based approach, we analyzed environmental variables, seagrass indicators, fish assemblages, and functional group (FG) dynamics across a thermal gradient extending from the effluent outfall itself. Results indicate that temperature is the dominant factor influencing P. oceanica, with reduced leaf length, shoot density, and rhizome weight characterizing samples closest to the effluent. Despite compensatory mechanisms, the overall photosynthetic biomass and resilience declined under thermal stress. Fish assemblages exhibited reduced species richness and biodiversity close to the thermal effluent, with opportunistic and thermophilic species dominating. An FG analysis revealed disrupted seasonal patterns, shifts in trophic dynamics, and functional compensation among species, highlighting potential ecological imbalances. Notably, transient predators thrived near the effluent, while more sedentary and temperate species were displaced. These findings underscore the cascading effects of rising temperatures on coastal habitats such as P. oceanica meadows and their associated communities, emphasizing the urgency for conservation measures. By identifying critical thresholds and adaptive responses, this study contributes valuable insights into the consequences of localized impacts of thermal stress on coastal biodiversity and ecosystem services.

Diadema aff. antillarum performs a key role in organizing and structuring rocky macroalgae assemblages in the Canary Islands; increased sea urchin population density can result in the formation of rocky grounds covered with crustose algae. In the Canary Islands this type of system alternates with non-crustose macroalgal systems. However, understanding of the process controlling formation, persistence and alternation between states is still poor. Moreover, knowledge of spatial and temporal variations of this key herbivore populations are scarce. Here an extensive study of D. aff. antillarum populations throughout the Canarian Archipelago were presented, with particular emphasis on two main themes: firstly the influence of sea urchin population on non-crustose macroalgal assemblages. Secondly, the spatial variation of adult sea urchin populations at different scales: both on a large scale (between islands and sites with different wave exposure) and on a medium-small scale (between dep...

Coral reef lagoons and back reef areas are composed more of sand than hard reef habitat. They support a diverse mix of fishes, including species restricted to sandy habitats and those dependent on both hard and soft substrata. However the resident assemblages associated with sand and the factors affecting their distribution and abundance are poorly understood. Here we examine spatial co-variation in the abundance of burrowing goby assemblages and habitat characteristics in the lagoon at Lizard Island (Great Barrier Reef). The aim was to identify which key habitat-variables should be incorporated into models to predict the structure of sand-dwelling fish communities. We focused on 10 common sand goby species from 7 genera: Amblyeleotris, Cryptocentrus, Ctenogobiops and Vanderhorstia (associated with burrows constructed by alpheid shrimps), and Amblygobius, Oplopomus and Valenciennea (free-living, burrowing species). Spatial patterns were examined by stratifying the lagoon into 6 recognizable habitat zones, and conducting visual transects in replicate sites within each zone. The abundance of all goby species encountered and habitat variables (depth, distance from reef, topography, disturbance of different types, sediment composition) were recorded in each transect. Habitat characteristics and fish abundance, diversity and species composition differed markedly among habitat types and sites within habitats. There was a strong association between sites grouped according to habitat characteristics and goby assemblage. These changes reflected species-specific responses to different combinations of habitat variables and their interactions. All habitat variables measured were at least partially correlated, either positively or negatively, with the abundance of some of the species. Depth, distance from consolidated reef, sediment composition and the level of disturbance were particularly important. Our study indicates that sandy habitats, although superficially uniform, support highly structured fish communities influenced by a wide range of factors.

We describe the synanthropic behavior of Lontra felina along its geographic distribution. The marine otter used fishing ports infrastructure for shelter and food. It forages on the remains of fish discarded by fishermen. Identified threats to the conservation of this species in synanthropy include incidental mortality in fisheries and persecution by domestic animals. The opportunities are creating niche food and shelter, which favor the permanence and population growth. Finally, we identify the important variables to consider in future studies on synanthropy of this marine mammal in the socioecological systems.

The marine otter Lontra felina has been said to prefer wave-exposed habitats over more protected sites in response to a greater prey abundance in exposed habitat. We examined how the foraging activity of L. felina is affected by the regime of wave exposure and prey availability at Isla Choros, northern Chile. Through focal sampling we recorded time spent by otters in foraging, the duration of dives, and the hunting success on a wave-exposed and a wave-protected site on the island. In addition, we quantified the abundance of prey in both habitats. Marine otters spent more time foraging in the wave-protected site compared with the wave-exposed habitat. Successful dives reached 26.9% in the wave-exposed habitats, and 38.2% in the wave-protected habitat. Foraging dives were 18% shorter in wave-exposed as compared with wave-protected habitat. Numerically, available prey did not differ significantly with habitat. Our results are more consistent with the hypothesis that wave-exposed habitats represent a sub-optimal habitat to foraging marine otters. Marine otters' use of wave-exposed patches through northern and central Chile coastal areas probably reflects a low availability of suitable protected areas and greater human disturbance of more protected habitat.

RESUMEN: En este trabajo se resumen los resultados preliminares obtenidos del estudio de las comunidades del «fouling» algal, que se establecieron sobre placas sumergidas en el puerto de Vigo, durante un periodo de seis meses. Aparte de la composición florística, interesante en algunos casos, se ha seguido la fijación de organismos mes a mes, así como la evolución de las comunidades en las que se integran durante el periodo de estudio.

In Arctic macroalgal belt ecosystems, macrozoobenthic production is thought to be an important link between primary production and higher trophic levels. Macrozoobenthic biomass and secondary production were studied along transects (2.5-15 m depth) in the macroalgal belt at Hansneset in Kongsfjorden, Svalbard, from 2012 to 2013. At 2.5 m, the standing stock reached its maxima of 174.8 ± 54.4 g ash-free dry weight per 1 m 2 , while density (4341 ind. m-2 ± 1127 95 % CI) and production (7.0 g C m-2 y-1 ± 2.8 95 % CI) were highest at 5 m water depth in 2012/13. Compared to a study from 1996/98, this re-sampling indicated a drastic change in the depth distribution of macrozoobenthic biomass and secondary production at Hansneset. While both biomass and secondary production increased with water depth in 1996/98, this pattern was inversed in 2012/13 owing to a tenfold increase in biomass and secondary production in the upper most sublittoral (2.5-5 m). Variability of macrozoobenthic biomass and secondary production corresponded to differences in the physical environment and macroalgal vegetation along the depth gradient. In the last decade, the number of ice-free days per year increased probably due to Arctic warming. As a result, shallow rocky habitats (2.5-5 m) are less affected by ice scouring, thereby opening new space for colonisation by benthic fauna. However, faunal secondary production was low compared to macroalgal primary production, indicating a considerable export of most of the algal production from the shallow habitats to the adjacent areas. Keywords Arctic Á Macrozoobenthic Á Kelp-associated fauna Á Benthic biomass Á Somatic production Á P/B ratio Á Kongsfjorden This article belongs to the special issue on the ''Kongsfjorden ecosystem-new views after more than a decade of research'', coordinated by Christian Wiencke and Haakon Hop.

In the Site of Community Interest (Natura, 2000) of Monte-da-Guia (Faial, Azores), two sites were delimited in order to investigate particularly the links between habitat characteristics, population structure, distribution and dynamics of the green alga Codium elisabethae. The first site is a large protected rocky seafloor of an ancient volcano crater (20m deep) and classified as no-go reserve. It shows very high density stands of Codium elisabethae (up to 105 ind.m -2 ), representing the main vegetal biomass. At similar depth but distant of about two kilometers, the second site is in a more exposed area, where a sparse population (about 13 ind.m -2 ) occupies rocky tables and boulders emerging from shallow sandy deposits. These contrasting densities reflect different population dynamic equilibrium resulting from the particular environmental pressures of each site. A two year population survey started in August 2003, aiming principally at building submarine image mosaics of each site on a seasonal basis. Further, a computer assisted detection is run on the images to derive valuable information about the studied macroalgae. This technique allows to study a comparatively large zone regarding to the diving time invested so as to integrate spatial patchiness and to focus on the temporal evolution of well identified individuals. The imagery methodology was validated with in situ measurements, confirming the adequacy of the 1cm precision size histograms produced, when considering individuals larger than 5cm diameter. Seasonal fluctuations of growth rate (from 0.5 to 3cm.month -1 ) and primary production (from 1 to 15kg.m-².month -1 ) could be described. For both sites studied, density, biomass and cover rate seemed affected by a seasonal variation with reduction starting in end summer early autumn. In both sites, the reduction was sharp in the fall 2003 and population density didn't recover completely in spring and summer 2004. During the following year, population of the protected site could maintain density and biomass, while population of the exposed site dropped continuously all year. Last processing step will search to relate statistically these different population evolutions to the benthic environmental constraints measured in both sites during the year 2004-2005 (temperature, currents, turbidity, photosynthetic active radiation, nutrients). Differences in hydrodynamic exposure of both sites could be part of the answer, but observed differences in the reproduction intensity of these two populations is an important factor, and remains unexplained.

Aside from the most notorious threats, the Mediterranean Sea faces novel and poorly
explored impacts from artificial light at night (ALAN), which influences natural light–dark cycles
and affects marine ecosystems. This study investigates the impact of ALAN on coastal infralittoral
assemblages in Malta, where such effects remain unexplored. Using Baited Remote Underwater
Videos (BRUVs), we examined the influence of different light intensities on species assemblages
and behaviour at two sites: a light-polluted harbour and a darker reef area. Our findings reveal
significant differences in fish community composition between light treatments and habitats. Among
the 23,955 individuals recorded across multiple taxa, Boops boops accounted for 80% of observations.
From our results, light intensity had a more substantial impact on community structure than habitat
type, with species-specific responses to light. Predatory species such as Trachurus trachurus displayed
increased activity under high-intensity white light, while Apogon imberbis and Serranus scriba were
more abundant under red light, irrespective of habitat. These results underscore the role of ALAN in
altering marine community dynamics and emphasise the need for sustainable management strategies
to mitigate its impact on the biodiversity of the Mediterranean. This study provides initial empirical
evidence of ALAN’s effects in Maltese waters, contributing to broader efforts to understand and
manage light pollution in marine ecosystems.

In the Site of Community Interest (Natura, 2000) of Monte-da-Guia (Faial, Azores), two sites were delimited in order to investigate particularly the links between habitat characteristics, population structure, distribution and dynamics of the green alga Codium elisabethae. The first site is a large protected rocky seafloor of an ancient volcano crater (20m deep) and classified as no-go reserve. It shows very high density stands of Codium elisabethae (up to 105 ind.m -2 ), representing the main vegetal biomass. At similar depth but distant of about two kilometers, the second site is in a more exposed area, where a sparse population (about 13 ind.m -2 ) occupies rocky tables and boulders emerging from shallow sandy deposits. These contrasting densities reflect different population dynamic equilibrium resulting from the particular environmental pressures of each site. A two year population survey started in August 2003, aiming principally at building submarine image mosaics of each site on a seasonal basis. Further, a computer assisted detection is run on the images to derive valuable information about the studied macroalgae. This technique allows to study a comparatively large zone regarding to the diving time invested so as to integrate spatial patchiness and to focus on the temporal evolution of well identified individuals. The imagery methodology was validated with in situ measurements, confirming the adequacy of the 1cm precision size histograms produced, when considering individuals larger than 5cm diameter. Seasonal fluctuations of growth rate (from 0.5 to 3cm.month -1 ) and primary production (from 1 to 15kg.m-².month -1 ) could be described. For both sites studied, density, biomass and cover rate seemed affected by a seasonal variation with reduction starting in end summer early autumn. In both sites, the reduction was sharp in the fall 2003 and population density didn't recover completely in spring and summer 2004. During the following year, population of the protected site could maintain density and biomass, while population of the exposed site dropped continuously all year. Last processing step will search to relate statistically these different population evolutions to the benthic environmental constraints measured in both sites during the year 2004-2005 (temperature, currents, turbidity, photosynthetic active radiation, nutrients). Differences in hydrodynamic exposure of both sites could be part of the answer, but observed differences in the reproduction intensity of these two populations is an important factor, and remains unexplained.

El genero Hypnea J.V. Lamouroux se caracteriza principalmente por presentar talos teretes ocomprimidos, ramas determinadas generalmente espiniformes, estructura interna compacta yuniaxial, tetrasporangios zonados, formando soros en las ramas determinadas y por laproduccion de κ-carragenina en su mayor proporcion. A nivel mundial existen 54 especies.Estudios floristicos previos realizados en Venezuela informaban de la presencia de cuatroespecies: Hypnea cornuta (Kutzing) J. Agardh, H. musciformis (Wulfen) J.V. Lamouroux, H.spinella (C. Agardh) Kutzing y H. valentiae (Turner) Montagne. El objetivo de este estudio es dar un primer aporte al conocimiento taxonomico del genero Hypnea para la costa de Venezuela,sobre la base de caracteres morfoanatomicos y reproductivos. Las colecciones de muestras botanicas fueron realizadas en localidades representativas de seis entidades federales: Aragua,Carabobo, Falcon, Miranda, Territorio Insular Francisco de Miranda (Parque NacionalArchipielago Lo...

To compare the general features of Thalassia testudinum seagrass at Mochima Bay with sea urchin (Lytechinus variegatus) abundance and distribution, three T. testudinum seagrass beds were selected, from the mouth (strong wave exposure) to the inner bay (calm waters). Each site was surveyed by using 5 line transects (20 m long) parallel to the coast and 1 m 2 quadrats. In situ measurements of T. testudinum cover, shoot and leaf density were taken. Estimation of dry biomass for each seagrass fraction (leaves, rhizomes and roots) and leaf length were obtained from 25 vegetation samples extracted per site using cores (15 cm diameter). A multivariate analysis of variance (Manova) and a less significative difference test (LSD) were performed to examine differences between sites and within sites at different depths. A stepwise multiple regression analysis was done, dependent variable was sea urchin density; independent variables: vegetation values at each site. The only seagrass species found in the three sites was T. testudinum, and cover was 56-100%, leaf density 100-1000 leaf/m 2 , lengths 6-18.8 cm and shoot density 20-475 shoots/m 2. The highest sea urchin densities were found at Isla Redonda and Ensenada Toporo (1-3.6 ind/m 2), the lowest at Playa Colorada (0.6-0.8 ind/m 2). Significant differences in seagrass features between sites were obtained (Manova p < 0.001), but not between depths (Manova p < 0.320). The regression coefficient between sea urchin density and seagrass parameters was statistically significant (r 2 = 0.154, p < 0.007), however, total biomass was the only variable with a significant effect on sea urchin distribution (ß = 0.308, p < 0.032). The other variables did not explain satisfactorily L. variegatus abundance and distribution.

The results of 93 phytosociological descriptions of five types of kelp forest from a number of phyto geographically distinct regions are presented. Methods are described for the measurement of a complex of meaningful ecosystem parameters which fall into three groups; individual performance, ecosystem performance and ecosystem potential. The results of such measurements in the phytosociologically defined units are presented.&quot; The validity of these results and the phytometer approach is discussed and tentative conclusions are drawn from the results regarding the biotic and abiotic components of the ecosystems.

Seaweed ingress into the cooling water intakes of nuclear power stations has caused several disruptions to electricity supply. Seaweed is transported by tidal and wave-induced currents after dislodgement from the sea bed following stormy conditions but ingress will be shown to be not only determined by wave conditions. An integrated model system has been developed to predict such ingress and applied at the Torness power station in Scotland where the mass of seaweed recovered was measured for some ingress cases. Prior to each case, seaweed is assumed initially to be distributed in areas surveyed within the surrounding coastal domain with a mass per unit area based on local measurements. Criteria for dislodgement are based on near-bed velocity. Six cases where the mass of ingress was measured and two cases with no ingress have been modelled and predicted by adjusting a dislodgement factor (a multiplier on the threshold velocity) within a relatively narrow range.

The marine otter Lontra felina has been said to prefer wave-exposed habitats over more protected sites in response to a greater prey abundance in exposed habitat. We examined how the foraging activity of L. felina is affected by the regime of wave exposure and prey availability at Isla Choros, northern Chile. Through focal sampling we recorded time spent by otters in foraging, the duration of dives, and the hunting success on a wave-exposed and a wave-protected site on the island. In addition, we quantified the abundance of prey in both habitats. Marine otters spent more time foraging in the wave-protected site compared with the wave-exposed habitat. Successful dives reached 26.9% in the wave-exposed habitats, and 38.2% in the wave-protected habitat. Foraging dives were 18% shorter in wave-exposed as compared with wave-protected habitat. Numerically, available prey did not differ significantly with habitat. Our results are more consistent with the hypothesis that wave-exposed habitats represent a sub-optimal habitat to foraging marine otters. Marine otters' use of wave-exposed patches through northern and central Chile coastal areas probably reflects a low availability of suitable protected areas and greater human disturbance of more protected habitat.

There are few comprehensive studies on the condition of reefs that are remote from direct anthropogenic pressures and, therefore, ecological baseline data are scarce. To help address this deficiency, the community condition of the little-studied remote reefs along a 200-kmlong tract bordering the Gulf of Batabano (southwest Cuba) was assessed. The reef-front coral communities (38 sites), where Montastraea spp. is the most common coral, were homogeneous along the entire reef tract. The reef-crest coral communities (30 sites), however, could be differentiated into three geographically distinct areas by their abundances of Acropora palmata and Diploria clivosa; the former predominated at 26 of the 30 reef-crest sites, but most colonies were “standing dead”. This observation is similar to the massive declines of acroporid coral populations that have been documented throughout the Caribbean region. Mean coral cover (19–26%) was similar to the regional average (19–23%), but was surprising...

Experimental tests of the hypothesis that ecological communities can exist in "multiple stable states" are rare, and some argue, impossible, because of the unlikelihood that any system will meet the necessary criteria. These are that alternative states (1) are in the same location, (2) experience the same environment, (3) persist for multiple generations, (4) resist repeated perturbations, and (5) result from a pulse manipulation. In 1974, we initiated an experiment testing the ability of Ascophyllum nodosum-dominated rocky intertidal communities to recover from complete canopy removal. Manipulations were monitored frequently for 5 yr after clearance and resurveyed again after a 35-yr hiatus. After clearance, Ascophyllum was replaced immediately by another fucoid alga, Fucus spp, which continued to dominate the space through 1979 despite regular annual recruitment by Ascophyllum. Observations in 2009 revealed that Fucus spp. still dominated the cleared plots. Surveys in 2011 and 2013 demonstrated that Fucus persisted in experimental plots and Ascophyllum persisted in adjacent, unmanipulated plots. All criteria for testing an alternative state were met. Fucus persisted through multiple generations of both fucoids, a steady annual rain of recruits of both species, a high frequency of storm-driven perturbations, and it resulted from a pulse manipulation. Likely mechanisms include poor Ascophyllum recruitment directly under the Fucus spp. canopy despite abundant recruitment in adjacent areas, self-maintenance by Fucus spp. through high recruitment and fast growth, and recruitment facilitation of Fucus by the barnacle Semibalanus balanoides. Several lines of evidence indicate that other possible mechanisms including indirect facilitation of fucoids through predation on competitors (mussels), and positive or negative effects of littorine grazing, are unlikely. Although prior results in Maine suggested that the mussel Mytilus edulis was an alternative stable state, the new results suggest that Fucus spp. was the alternative state to Ascophyllum. During the nearly four decades of this experiment, a number of important species including fucoids, littorine grazers, and mussels all declined in abundance, most likely due to climate change. The presumed impact of climate change makes prediction of the long-term response of this system difficult, but it already differs dramatically from its structure in the 1970s.

RESUMEN Antecedentes. La flora de algas marinas bénticas del Pacífico colombiano pertenece a las áreas menos conocidas del Pacífico Tropical Oriental, reportándose en total 133 especies. Esta diversidad algal es relativamente baja, comparada con la registrada en el Caribe Colombiano, que suma 549 especies. Objetivos. El presente trabajo evaluó la diversidad

Experimental tests of the hypothesis that ecological communities can exist in "multiple stable states" are rare, and some argue, impossible, because of the unlikelihood that any system will meet the necessary criteria. These are that alternative states (1) are in the same location, (2) experience the same environment, (3) persist for multiple generations, (4) resist repeated perturbations, and (5) result from a pulse manipulation. In 1974, we initiated an experiment testing the ability of Ascophyllum nodosum-dominated rocky intertidal communities to recover from complete canopy removal. Manipulations were monitored frequently for 5 yr after clearance and resurveyed again after a 35-yr hiatus. After clearance, Ascophyllum was replaced immediately by another fucoid alga, Fucus spp, which continued to dominate the space through 1979 despite regular annual recruitment by Ascophyllum. Observations in 2009 revealed that Fucus spp. still dominated the cleared plots. Surveys in 2011 and 2013 demonstrated that Fucus persisted in experimental plots and Ascophyllum persisted in adjacent, unmanipulated plots. All criteria for testing an alternative state were met. Fucus persisted through multiple generations of both fucoids, a steady annual rain of recruits of both species, a high frequency of storm-driven perturbations, and it resulted from a pulse manipulation. Likely mechanisms include poor Ascophyllum recruitment directly under the Fucus spp. canopy despite abundant recruitment in adjacent areas, self-maintenance by Fucus spp. through high recruitment and fast growth, and recruitment facilitation of Fucus by the barnacle Semibalanus balanoides. Several lines of evidence indicate that other possible mechanisms including indirect facilitation of fucoids through predation on competitors (mussels), and positive or negative effects of littorine grazing, are unlikely. Although prior results in Maine suggested that the mussel Mytilus edulis was an alternative stable state, the new results suggest that Fucus spp. was the alternative state to Ascophyllum. During the nearly four decades of this experiment, a number of important species including fucoids, littorine grazers, and mussels all declined in abundance, most likely due to climate change. The presumed impact of climate change makes prediction of the long-term response of this system difficult, but it already differs dramatically from its structure in the 1970s.

Experimental tests of the hypothesis that ecological communities can exist in "multiple stable states" are rare, and some argue, impossible, because of the unlikelihood that any system will meet the necessary criteria. These are that alternative states (1) are in the same location, (2) experience the same environment, (3) persist for multiple generations, (4) resist repeated perturbations, and (5) result from a pulse manipulation. In 1974, we initiated an experiment testing the ability of Ascophyllum nodosum-dominated rocky intertidal communities to recover from complete canopy removal. Manipulations were monitored frequently for 5 yr after clearance and resurveyed again after a 35-yr hiatus. After clearance, Ascophyllum was replaced immediately by another fucoid alga, Fucus spp, which continued to dominate the space through 1979 despite regular annual recruitment by Ascophyllum. Observations in 2009 revealed that Fucus spp. still dominated the cleared plots. Surveys in 2011 and 2013 demonstrated that Fucus persisted in experimental plots and Ascophyllum persisted in adjacent, unmanipulated plots. All criteria for testing an alternative state were met. Fucus persisted through multiple generations of both fucoids, a steady annual rain of recruits of both species, a high frequency of storm-driven perturbations, and it resulted from a pulse manipulation. Likely mechanisms include poor Ascophyllum recruitment directly under the Fucus spp. canopy despite abundant recruitment in adjacent areas, self-maintenance by Fucus spp. through high recruitment and fast growth, and recruitment facilitation of Fucus by the barnacle Semibalanus balanoides. Several lines of evidence indicate that other possible mechanisms including indirect facilitation of fucoids through predation on competitors (mussels), and positive or negative effects of littorine grazing, are unlikely. Although prior results in Maine suggested that the mussel Mytilus edulis was an alternative stable state, the new results suggest that Fucus spp. was the alternative state to Ascophyllum. During the nearly four decades of this experiment, a number of important species including fucoids, littorine grazers, and mussels all declined in abundance, most likely due to climate change. The presumed impact of climate change makes prediction of the long-term response of this system difficult, but it already differs dramatically from its structure in the 1970s.

Morphological development of Laminaria hyperborea was examined at localities with different degrees of wave exposure. Biomass data were converted to estimates of annual growth of lamina, stipe and hapteron. Allocation of annual growth to the hapteron constituted a small amount of the total production, but increased with increasing wave exposure. At the most sheltered locality, lamina growth amounted to between 80 and 95% of total growth in all age groups, and lamina to stipe ratios (fresh weight) were about 10. A higher portion of the annual growth was allocated to the stipe at the more wave-exposed localities. This resulted in lamina to stipe ratios of between 1 and 2 in old plants, but within these localities no gradual decrease in lamina to stipe ratio with increasing wave exposure was observed. At some localities a maximum of growth allocation to the stipe was found in the intermediate age groups. This was most pronounced at the locality with the highest density of canopy plants and intermediate wave exposure. Also, at this locallty the stipes were longer in relation to their weight than at the other localities. These results indicate that light environment, in additlon to wave exposure, Inay influence the stipe morphology and the relationship between stipe and lamina growth. At one station stipe growth was also calculated in individual tagged plants using the lengthweight relationship. The results agreed with those obtained by the biomass method. The highest allocation of growth to the stipes was found in 3 and 4 yr old plants. Maximum annual stipe growth (weight increase) occurred in 4 and 5 yr old plants and decreased in older plants, while maximum lamina growth was found in the oldest plants.

The Torrey Canyon was wrecked in 1967 with 117,000 tons of crude oil on board. The Plymouth Laboratory of the Marine Biological Association (MBA) of the UK was mobilized to deal with this environmental catastrophe. Many of the rocky shores affected by the spill and unaffected control sites had been studied by staff from the MBA, with A.J. and E.C. Southward charting fluctuations of rocky shore fauna and flora from the early 1950s – particularly barnacles – in relation to climate. Thus a baseline existed to help judge recovery of rocky shores from the beached oil and application of toxic first generation dispersants. A reminder is given of the initial acute impacts of the oil and its treatment by dispersants, and the first ten years of observations on recovery of shore communities. Subsequent follow-up work in the 1980s and 1990s suggested recovery took up to 15 years on the shore (Porthleven) subject to the most severe dispersant application. In contrast, recovery occurred in 2–3 ye...

Summary Small‐scale distributions of rocky intertidal organisms may be determined in part by temperature and desiccation stress during low tide and the ability of organisms to resist such stresses. Biophysical modelling techniques, coupled with data on the physiological tolerance of organisms can be used to predict the frequency and severity of abiotic stress events. The limpet Lottia gigantea is a major competitor for primary space on rocky shores along the west coast of North America. The goal of this study was to quantify the thermal and desiccation tolerance of this species and to predict the frequency of stressful events at Hopkins Marine Station (HMS) in Pacific Grove, CA, USA. Lottia gigantea were exposed to thermal stress regimes in the laboratory using protocols designed to mimic prolonged exposures in the field. The production of heat shock protein 70 (Hsp70) was measured as an indicator of sub‐lethal stress, and mortality rates were measured. Peak expression of Hsp70 occu...

Aspartate aminotransferase and alanine aminotransferase activity levels were determined in crude homogenates of Littorina arcana, Littorina littorea, Littorina compressa, Littorina neglecta, Littorina obtusata, Littorina fabalis, Melarhaphe neritoides and three forms of Littorina saxatilis; high shore thin-shelled H, midshore thick-shelled M and barnacle dwelling B. In all the groups investigated, aspartate aminotransferase activity was higher than alanine aminotransferase, and high shore species appeared to have higher activity levels of aspartate aminotransferase relative to alanine aminotransferase than did low shore species. Aspartate aminotransferase was more heat stable than alanine aminotransferase at 458C, and it was more heat stable in high shore than in low shore groups. Heat stability also varied within a species; the enzymes of L. saxatilis H were more heat stable than those of L. saxatilis M from the same site. The enzymes of a small-barnacle dwelling form of L. saxatilis showed greater heat stability than sympatric samples of L. neglecta. The possible factors involved in these differences are discussed.