Luis Giménez - Academia.edu (original) (raw)

Papers by Luis Giménez

Developmental Biology and Larval Ecology, 2020

The vast majority of crustaceans are aquatic, living in either marine or freshwater environments.... more The vast majority of crustaceans are aquatic, living in either marine or freshwater environments. Marine crustaceans—such as copepods, in particular—are ubiquitous in the oceans and perhaps the most numerous metazoans on Earth. Because crustaceans occur in all marine habitats, their larvae are exposed to highly diverse and sometimes variable environmental conditions, including extreme situations in which various environmental factors exert significant effects on larval growth and development. This chapter first describes the effects of food availability on crustacean larvae. Food paucity is a commonly occurring scenario in the wild, which can directly affect larval growth and development and, in severe cases, results in mortality. In the subsequent sections, we cover the effects of temperature and salinity—the two most prominent physical parameters in the aquatic environments—on growth and development of crustacean larvae. We then discuss the influence of other important physicochem...

Pelagic Sargassum and floating marine debris were collected during cruise MSM41 of the German res... more Pelagic Sargassum and floating marine debris were collected during cruise MSM41 of the German research vessel Maria S. Merian in April 2015 in the Sargasso Sea, western subtropical North Atlantic. In total 39 debris samples and 42 Sargassum samples were taken and characterized. The associated biota was analyzed. Mobile species were counted, sessile organisms were recorded as present/absent. A visual ship-based survey was conducted to quantify pelagic Sargassum and floating marine debris in the Sargasso Sea. Biomass and surface area of Sargassum was measured from thalli beached at Sisal Beach, Yucatan peninsula, Mexico to establish the biomass:surface area ratio for the two species Sargassum fluitans and Sargassum natans.

World Aquaculture Adelaide, Create, Nurture, Grow, 7-11 June 2014, Adelaide, South Australia.-- 1... more World Aquaculture Adelaide, Create, Nurture, Grow, 7-11 June 2014, Adelaide, South Australia.-- 1 page, 1 figure

Intertidal serrated wrack Fucus serratus is common throughout the temperate N-Atlantic and plays ... more Intertidal serrated wrack Fucus serratus is common throughout the temperate N-Atlantic and plays an important role as a bioengineering species structuring lower intertidal communities. Several studies have addressed the impact of Fucus cover and its disturbance on species richness, diversity and succession of associated species in manipulative experiments. However, natural catastrophic events have scarcely been followed on a spatial mesoscale. We analyzed a 10-yrs time series on 140 permanent geo-referenced plots in the intertidal zone at the island of Helgoland (North Sea) covering an area of approx. 100 x 100 m. Samples were taken biannually in winter and summer. We describe the general intra- and interannual dynamics of F. serratus coverage and associated seaweed and mollusk species. The spatio-temporal extent and percentage coverage of F. serratus displayed a regular intra-annual pattern with lower coverage in winter than in summer whereas the spatial extent of the zone remained...

Environmental Pollution, 2021

Offshore human activities lead to increasing amounts of underwater noise in coastal and shelf env... more Offshore human activities lead to increasing amounts of underwater noise in coastal and shelf environments, which may affect commercially-important benthic invertebrate groups like the restocked Helgoland European lobster (Homarus gammarus) in the German Bight (North Sea). It is crucial to understand the impact tonal lowfrequency noises, like maritime transport and offshore energy operations, may have on substrate choice and lobsters' behavior to assess potential benefits or bottlenecks of new hard-substrate artificial offshore environments that become available. In this study, we investigated the full factorial effect of a tonal low-frequency noise and predator presence on young-of-year (YOY) European lobsters' in a diurnal and nocturnal experiment. Rocks and European oyster shells (Ostrea edulis) were offered as substrate to YOY lobsters for 3 h. Video recordings (n = 134) allowed the identification of lobsters' initial substrate choice, diel activity and key behaviors (peeking, shelter construction, exploration and hiding). To ensure independence, YOY lobsters in the intermolt stage were randomly selected and assigned to the experimental tanks and used only once. We provide the first evidence that stressors alone, and in combination, constrain YOY lobsters' initial substrate choice towards rocks. During nighttime, the joint effect of exposure to a constant low-frequency noise and predator presence decreased antipredator behavior (i.e., hiding) and increased exploration behavior. Noise may thus interfere with YOY lobsters' attention and decision-making processes. This outcome pinpoints that added tonal low-frequency noise in the environment have the potential to influence the behavior of early-life stages of European lobsters under predator pressure and highlights the importance of including key benthic invertebrates' community relationships in anthropogenic noise risk assessments. Among others, effects of noise must be taken into consideration in plans involving the multi-use of any offshore area for decapods' stock enhancement, aquaculture, and temporary notake zones.

Marine and Freshwater Research, 2017

The benthic trophic status of Uruguayan coastal estuarine habitats (permanently open estuaries an... more The benthic trophic status of Uruguayan coastal estuarine habitats (permanently open estuaries and open or closed coastal lagoons) was evaluated, twice in 1 year and at different spatial scales, using the amount and biochemical composition of the sedimentary organic matter. Nested hierarchical ANOVAs were applied to evaluate differences at the habitat level, among sites for each type of estuarine habitat (three estuaries and three lagoons) and between sectors located at different distances from the sea (inner v. outer sectors). Morphological and hydrodynamic differences between the two types of habitats explained site-to-site variations in eutrophic conditions in the open or closed coastal lagoons and meso-oligotrophic conditions in permanently open estuaries. These differences followed the patterns found for sediment grain size, with inner sectors (lower-energy areas) favouring the accumulation of finer sediments and higher amounts of degraded–detrital organic matter. In autumn, bi...

Marine Ecology Progress Series, 2016

One of the central issues in ecology is the identification of processes affecting the population ... more One of the central issues in ecology is the identification of processes affecting the population structure and dynamics of species with complex life cycles. In such species, variation in both the number of larvae that enter a population and their phenotype are important drivers of survival and growth after metamorphosis. Larval experience can have strong effects on key postmetamorphic traits, but the temporal scale of such 'trait-mediated effects' may be short, and their magnitude may depend on the environment experienced after metamorphosis. We used an intertidal barnacle to study the long-term consequences of trait-mediated effects under different postmetamorphic conditions by manipulating larval food concentration and monitoring patterns of survival and growth in juveniles at 2 intertidal levels over a 5 mo period. In 2 replicated experiments, higher food levels resulted in increased body size, mass and reserves (measured from elemental composition) in the settling larval stage and increased body size of newly metamorphosed juveniles. In Expt 1, high food concentration reduced juvenile mortality at low intertidal levels, while on the upper intertidal, mortality was high for all larval food concentrations. By contrast, in Expt 2, low larval food concentration decreased juvenile survival at both shore levels. When present, effects were established early (Weeks 1 or 2) and persisted for over 10 wk in Expt 1 and 22 wk in Expt 2. Interactive effects of the larval and juvenile environments can have important implications for population size: trait-mediated effects may persist for long periods, helping to explain patterns of adult abundance.

Journal of the Marine Biological Association of the United Kingdom, 2008

Rafting on floating macroalgae is a common dispersal mechanism of marine benthic invertebrates. M... more Rafting on floating macroalgae is a common dispersal mechanism of marine benthic invertebrates. Most benthic macroalgae are inhabited by diverse epifaunal communities but not all organisms may be adapted to live on floating algae. In particular, knowledge about the immediate effects of algal detachment on the associated biota is limited. Herein, we studied the composition of the communities of mobile invertebrates on benthic thalli of Ascophyllum nodosum and compared it with detached thalli that had floated for short periods. The community of the mobile invertebrates changed significantly within the first minute after detachment of the algae and showed decreased diversity and a tendency towards reduced abundances in most taxa. However, during the subsequent two hours of floating at the sea surface the species composition did not change further. A comparison of the size-spectra of the gastropod Littorina obtusata from attached and detached algae did not reveal differential migratory ...

Marine Ecology Progress Series, 2009

Settlement is the process by which pelagic larval stages colonize the sea bottom. Variations in s... more Settlement is the process by which pelagic larval stages colonize the sea bottom. Variations in settlement rates can affect population dynamics and community structure. Here I study the importance of spatial and temporal scales of mobility of larvae to define settlement rates of marine species with complex life cycles, and the uncertainty in their estimation. Larvae of mobile marine species (e.g. fish, crabs) arrive at the sea bottom but still swim or crawl for several days, covering considerable distances. This behaviour affects the operational definition of settlement because an observer cannot differentiate between new and old settlers. I model the process of estimation of settlement rate for these organisms incorporating the characteristics of settlers and the process of observation. Settlers are characterised by the temporal and spatial scales of movement within a homogeneous area. The process of observation is characterised by the grain and step (= spatial and temporal resolution) of the sampling design, i.e. the size of the observed site and the time between 2 consecutive observations. As the resolution increases, the uncertainty in the estimation of settlement also increases. There are critical spatial and temporal scales below which the uncertainty is high and evaluation of patterns of settlement is not possible. Uncertainty relationships should be considered in designing sampling schemes to study patterns of settlement without the confounding effect of the subsequent movements of individuals within the settlement habitat. Relationships of this kind may also appear in other fields of ecology.

Marine Biology, 2012

The brown shrimp Crangon crangon is a key species in the coastal areas of the North Sea. It const... more The brown shrimp Crangon crangon is a key species in the coastal areas of the North Sea. It constitutes a significant food source for fishes. Simultaneously, it is an important predator on a wide range of invertebrates. C. crangon shows a variety of digestive enzymes that allow to utilizing a wide range of food items. The initial step of alimentary protein digestion, that is the degradation into peptides, is facilitated by set of endopeptidases which are expressed by the midgut gland. In crustaceans, these endopeptidases are often dominated by serine proteinases. C. crangon, however, predominantly express cysteine proteinases, while only some specimens show a highly variable pattern of serine proteinases. The composition of these serine endopeptidases was investigated using liquid chromatography, substrate gel electrophoresis and inhibitor assays. Distinctly elevated activities were present only in about 10% of the samples. When activity was detected, two peaks, one with tryptic activity and the other one with chymotryptic activity, could be separated by anionic exchange chromatography. Moreover, specimens with elevated tryptic activities often showed highly polymorphic patterns of endopeptidases after electrophoretic separation. Overall, 30 different bands of endopeptidases were identified. There was no similarity between animals from the same sampling sites, neither between animals of similar size, weight or nutritive state. The polymorphism of proteinase from the midgut gland seems to reflect the high adaptive potential of this species to variable trophic conditions in a continuously changing environment.

Aquatic Biology, 2011

Marine invertebrate larvae suffer high mortality due to abiotic and biotic stress. In planktotrop... more Marine invertebrate larvae suffer high mortality due to abiotic and biotic stress. In planktotrophic larvae, mortality may be minimised if growth rates are maximised. In estuaries and coastal habitats however, larval growth may be limited by salinity stress, which is a key factor selecting for particular physiological adaptations such as osmoregulation. These mechanisms may be energetically costly, leading to reductions in growth. Alternatively, the metabolic costs of osmoregulation may be offset by the capacity maintaining high growth at low salinities. Here we attempted identify general response patterns in larval growth at reduced salinities by comparing 12 species of decapod crustaceans with differing levels of tolerance to low salinity and differing osmoregulatory capability, from osmoconformers to strong osmoregulators. Larvae possessing tolerance to a wider range in salinity were only weakly affected by low salinity levels. Larvae with a narrower tolerance range, by contrast, generally showed reductions in growth at low salinity. The negative effect of low salinity on growth decreased with increasing osmoregulatory capacity. Therefore, the ability to osmoregulate allows for stable growth. In euryhaline larval decapods, the capacity to maintain high growth rates in physically variable environments such as estuaries appears thus to be largely unaffected by the energetic costs of osmoregulation.

Ecology and Evolution, 2021

This is an open access article under the terms of the Creative Commons Attribution License, which... more This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Scientific Reports

Understanding biological responses to environmental fluctuations (e.g. heatwaves) is a critical g... more Understanding biological responses to environmental fluctuations (e.g. heatwaves) is a critical goal in ecology. Biological responses (e.g. survival) are usually measured with respect to different time reference frames, i.e. at specific chronological times (e.g. at specific dates) or biological times (e.g. at reproduction). Measuring responses on the biological frame is central to understand how environmental fluctuation modifies fitness and population persistence. We use a framework, based on partial differential equations (PDEs) to explore how responses to the time scale and magnitude of fluctuations in environmental variables (= drivers) depend on the choice of reference frame. The PDEs and simulations enabled us to identify different components, responsible for the phenological and eco-physiological effects of each driver on the response. The PDEs also highlight the conditions when the choice of reference frame affects the sensitivity of the response to a driver and the type of ...

Developmental Biology and Larval Ecology, 2020

This volume examines Developmental Biology and Larval Ecology, Chapters in this volume synthesize... more This volume examines Developmental Biology and Larval Ecology, Chapters in this volume synthesize our current understanding of early crustacean development from the egg through the embryonic and larval phase. The first part of this volume focuses on the fundamental aspects of crustacean embryonic development. The second part of the book provides an account of the larval phase of crustaceans and describes processes that influence the development from hatching to an adult-like juvenile. The third and final part of the book explores ecological interactions during the planktonic phase and how crustacean larvae manage to find food, navigate the dynamic water column, and avoid predators in a medium that offers few refuges. Collectively, these fifteen chapters provide a thorough overview of our present knowledge across the major themes in crustacean developmental biology and larval ecology. We expect this volume will be valuable to scholars and students who are interested in gaining deeper...

Ecography, 2020

Predicting range expansion of invasive species is one of the key challenges in ecology. We modell... more Predicting range expansion of invasive species is one of the key challenges in ecology. We modelled the phenological window for successful larval release and development (WLR) in order to predict poleward expansion of the invasive crab Hemigrapsus sanguineus along the Atlantic coast of North America and north Europe. WLR quantifies the number of opportunities (in days) when larval release leads to a successful completion of the larval phase; WLR depends on the effects of temperature on the duration of larval development and survival. Successful larval development is a necessary requirement for the establishment of self-persistent local populations. WLR was computed from a mechanistic model, based on in situ temperature time series and a laboratory-calibrated curve predicting duration of larval development from temperature. As a validation step, we checked that model predictions of the time of larval settlement matched observations from the field for our local population (Helgoland, North Sea). We then applied our model to the North American shores because larvae from our European population showed, in the laboratory, similar responses to temperature to those of a North American population. WLR correctly predicted the northern distribution limit in North American shores, where the poleward expansion of H. sanguineus appear to have stalled (as of 2015). For north Europe, where H. sanguineus is a recent invader, WLR predicted ample room for poleward expansion towards NE England and S Norway. We also explored the importance of year-to-year variation in temperature for WLR and potential expansion: variations in WLR highlighted the role of heat waves as likely promoters of recruitment subsidising sink populations located at the distribution limits. Overall, phenological windows may be used as a part of a warning system enabling more targeted programs for monitoring.

Helgoland Marine Research, 2003

Scientific reports, Jan 23, 2018

Marine crabs inhabit shallow coastal/estuarine habitats particularly sensitive to climate change,... more Marine crabs inhabit shallow coastal/estuarine habitats particularly sensitive to climate change, and yet we know very little about the diversity of their responses to environmental change. We report the effects of a rarely studied, but increasingly prevalent, combination of environmental factors, that of near-future pCO (~1000 µatm) and a physiologically relevant 20% reduction in salinity. We focused on two crab species with differing abilities to cope with natural salinity change, and revealed via physiological and molecular studies that salinity had an overriding effect on ion exchange in the osmoregulating shore crab, Carcinus maenas. This species was unaffected by elevated CO, and was able to hyper-osmoregulate and maintain haemolymph pH homeostasis for at least one year. By contrast, the commercially important edible crab, Cancer pagurus, an osmoconformer, had limited ion-transporting capacities, which were unresponsive to dilute seawater. Elevated CO disrupted haemolymph pH h...

Brazilian Journal of Oceanography, 2010

The seasonal dynamics of the fish community in the Pando estuary on the Uruguayan coast were stud... more The seasonal dynamics of the fish community in the Pando estuary on the Uruguayan coast were studied in relation to environmental sampled monthly between May 2002 and June 2003. Individuals collected were identified, and classified into stages (juveniles, adults) and functional groups. Relationships between community dynamics and environmental variables were evaluated using uni- and multivariate techniques. Twenty-one species, mostly freshwater stragglers, estuarine and marine migrants were collected. The most abundant species were Micropogonias furnieri, Mugil platanus, Paralichthys orbignyanus and Brevoortia aurea and were represented by juveniles. The community varied seasonally with rapid shifts in spring and autumn associated with changes in temperature and salinity. Significant correlations between abundance and temperature may be related to the timing of life cycle events. In this estuary, the salinity appears to play a key role in the functional structure and in the use of t...

Marine Ecology Progress Series, 2017

Journal of Plankton Research, 2014

We evaluate the potential for decapod larvae to develop under temporally limited daily access to ... more We evaluate the potential for decapod larvae to develop under temporally limited daily access to food across a broad thermal range. Larvae of the European lobster Homarus gammarus and velvet swimming crab Necora puber were successfully reared to juvenile and megalopa stages, respectively, at four temperatures (range 15-248C) under both permanent (24 h) and limited (4 h) daily access to prey. Survival was high in both species with no consistent effect of food limitation. Larvae developed faster with increasing temperature. Model selection indicated that limited access to food in N. puber slowed development from zoea III onwards by 10-25% depending on stage and temperature. Food limitation slowed development of H. gammarus in zoea III and stage IV by 6-30%, with significant interactions of food  temperature. Dry mass, carbon and nitrogen content of H. gammarus all decreased with temperature and were lower under limited access to food. Decapod larvae of the tested species show a high potential to survive and develop with a temporally patchy food resource, although a longer development and smaller body mass at the time of settlement may lead to fitness costs.

Developmental Biology and Larval Ecology, 2020

The vast majority of crustaceans are aquatic, living in either marine or freshwater environments.... more The vast majority of crustaceans are aquatic, living in either marine or freshwater environments. Marine crustaceans—such as copepods, in particular—are ubiquitous in the oceans and perhaps the most numerous metazoans on Earth. Because crustaceans occur in all marine habitats, their larvae are exposed to highly diverse and sometimes variable environmental conditions, including extreme situations in which various environmental factors exert significant effects on larval growth and development. This chapter first describes the effects of food availability on crustacean larvae. Food paucity is a commonly occurring scenario in the wild, which can directly affect larval growth and development and, in severe cases, results in mortality. In the subsequent sections, we cover the effects of temperature and salinity—the two most prominent physical parameters in the aquatic environments—on growth and development of crustacean larvae. We then discuss the influence of other important physicochem...

Pelagic Sargassum and floating marine debris were collected during cruise MSM41 of the German res... more Pelagic Sargassum and floating marine debris were collected during cruise MSM41 of the German research vessel Maria S. Merian in April 2015 in the Sargasso Sea, western subtropical North Atlantic. In total 39 debris samples and 42 Sargassum samples were taken and characterized. The associated biota was analyzed. Mobile species were counted, sessile organisms were recorded as present/absent. A visual ship-based survey was conducted to quantify pelagic Sargassum and floating marine debris in the Sargasso Sea. Biomass and surface area of Sargassum was measured from thalli beached at Sisal Beach, Yucatan peninsula, Mexico to establish the biomass:surface area ratio for the two species Sargassum fluitans and Sargassum natans.

World Aquaculture Adelaide, Create, Nurture, Grow, 7-11 June 2014, Adelaide, South Australia.-- 1... more World Aquaculture Adelaide, Create, Nurture, Grow, 7-11 June 2014, Adelaide, South Australia.-- 1 page, 1 figure

Intertidal serrated wrack Fucus serratus is common throughout the temperate N-Atlantic and plays ... more Intertidal serrated wrack Fucus serratus is common throughout the temperate N-Atlantic and plays an important role as a bioengineering species structuring lower intertidal communities. Several studies have addressed the impact of Fucus cover and its disturbance on species richness, diversity and succession of associated species in manipulative experiments. However, natural catastrophic events have scarcely been followed on a spatial mesoscale. We analyzed a 10-yrs time series on 140 permanent geo-referenced plots in the intertidal zone at the island of Helgoland (North Sea) covering an area of approx. 100 x 100 m. Samples were taken biannually in winter and summer. We describe the general intra- and interannual dynamics of F. serratus coverage and associated seaweed and mollusk species. The spatio-temporal extent and percentage coverage of F. serratus displayed a regular intra-annual pattern with lower coverage in winter than in summer whereas the spatial extent of the zone remained...

Environmental Pollution, 2021

Offshore human activities lead to increasing amounts of underwater noise in coastal and shelf env... more Offshore human activities lead to increasing amounts of underwater noise in coastal and shelf environments, which may affect commercially-important benthic invertebrate groups like the restocked Helgoland European lobster (Homarus gammarus) in the German Bight (North Sea). It is crucial to understand the impact tonal lowfrequency noises, like maritime transport and offshore energy operations, may have on substrate choice and lobsters' behavior to assess potential benefits or bottlenecks of new hard-substrate artificial offshore environments that become available. In this study, we investigated the full factorial effect of a tonal low-frequency noise and predator presence on young-of-year (YOY) European lobsters' in a diurnal and nocturnal experiment. Rocks and European oyster shells (Ostrea edulis) were offered as substrate to YOY lobsters for 3 h. Video recordings (n = 134) allowed the identification of lobsters' initial substrate choice, diel activity and key behaviors (peeking, shelter construction, exploration and hiding). To ensure independence, YOY lobsters in the intermolt stage were randomly selected and assigned to the experimental tanks and used only once. We provide the first evidence that stressors alone, and in combination, constrain YOY lobsters' initial substrate choice towards rocks. During nighttime, the joint effect of exposure to a constant low-frequency noise and predator presence decreased antipredator behavior (i.e., hiding) and increased exploration behavior. Noise may thus interfere with YOY lobsters' attention and decision-making processes. This outcome pinpoints that added tonal low-frequency noise in the environment have the potential to influence the behavior of early-life stages of European lobsters under predator pressure and highlights the importance of including key benthic invertebrates' community relationships in anthropogenic noise risk assessments. Among others, effects of noise must be taken into consideration in plans involving the multi-use of any offshore area for decapods' stock enhancement, aquaculture, and temporary notake zones.

Marine and Freshwater Research, 2017

The benthic trophic status of Uruguayan coastal estuarine habitats (permanently open estuaries an... more The benthic trophic status of Uruguayan coastal estuarine habitats (permanently open estuaries and open or closed coastal lagoons) was evaluated, twice in 1 year and at different spatial scales, using the amount and biochemical composition of the sedimentary organic matter. Nested hierarchical ANOVAs were applied to evaluate differences at the habitat level, among sites for each type of estuarine habitat (three estuaries and three lagoons) and between sectors located at different distances from the sea (inner v. outer sectors). Morphological and hydrodynamic differences between the two types of habitats explained site-to-site variations in eutrophic conditions in the open or closed coastal lagoons and meso-oligotrophic conditions in permanently open estuaries. These differences followed the patterns found for sediment grain size, with inner sectors (lower-energy areas) favouring the accumulation of finer sediments and higher amounts of degraded–detrital organic matter. In autumn, bi...

Marine Ecology Progress Series, 2016

One of the central issues in ecology is the identification of processes affecting the population ... more One of the central issues in ecology is the identification of processes affecting the population structure and dynamics of species with complex life cycles. In such species, variation in both the number of larvae that enter a population and their phenotype are important drivers of survival and growth after metamorphosis. Larval experience can have strong effects on key postmetamorphic traits, but the temporal scale of such 'trait-mediated effects' may be short, and their magnitude may depend on the environment experienced after metamorphosis. We used an intertidal barnacle to study the long-term consequences of trait-mediated effects under different postmetamorphic conditions by manipulating larval food concentration and monitoring patterns of survival and growth in juveniles at 2 intertidal levels over a 5 mo period. In 2 replicated experiments, higher food levels resulted in increased body size, mass and reserves (measured from elemental composition) in the settling larval stage and increased body size of newly metamorphosed juveniles. In Expt 1, high food concentration reduced juvenile mortality at low intertidal levels, while on the upper intertidal, mortality was high for all larval food concentrations. By contrast, in Expt 2, low larval food concentration decreased juvenile survival at both shore levels. When present, effects were established early (Weeks 1 or 2) and persisted for over 10 wk in Expt 1 and 22 wk in Expt 2. Interactive effects of the larval and juvenile environments can have important implications for population size: trait-mediated effects may persist for long periods, helping to explain patterns of adult abundance.

Journal of the Marine Biological Association of the United Kingdom, 2008

Rafting on floating macroalgae is a common dispersal mechanism of marine benthic invertebrates. M... more Rafting on floating macroalgae is a common dispersal mechanism of marine benthic invertebrates. Most benthic macroalgae are inhabited by diverse epifaunal communities but not all organisms may be adapted to live on floating algae. In particular, knowledge about the immediate effects of algal detachment on the associated biota is limited. Herein, we studied the composition of the communities of mobile invertebrates on benthic thalli of Ascophyllum nodosum and compared it with detached thalli that had floated for short periods. The community of the mobile invertebrates changed significantly within the first minute after detachment of the algae and showed decreased diversity and a tendency towards reduced abundances in most taxa. However, during the subsequent two hours of floating at the sea surface the species composition did not change further. A comparison of the size-spectra of the gastropod Littorina obtusata from attached and detached algae did not reveal differential migratory ...

Marine Ecology Progress Series, 2009

Settlement is the process by which pelagic larval stages colonize the sea bottom. Variations in s... more Settlement is the process by which pelagic larval stages colonize the sea bottom. Variations in settlement rates can affect population dynamics and community structure. Here I study the importance of spatial and temporal scales of mobility of larvae to define settlement rates of marine species with complex life cycles, and the uncertainty in their estimation. Larvae of mobile marine species (e.g. fish, crabs) arrive at the sea bottom but still swim or crawl for several days, covering considerable distances. This behaviour affects the operational definition of settlement because an observer cannot differentiate between new and old settlers. I model the process of estimation of settlement rate for these organisms incorporating the characteristics of settlers and the process of observation. Settlers are characterised by the temporal and spatial scales of movement within a homogeneous area. The process of observation is characterised by the grain and step (= spatial and temporal resolution) of the sampling design, i.e. the size of the observed site and the time between 2 consecutive observations. As the resolution increases, the uncertainty in the estimation of settlement also increases. There are critical spatial and temporal scales below which the uncertainty is high and evaluation of patterns of settlement is not possible. Uncertainty relationships should be considered in designing sampling schemes to study patterns of settlement without the confounding effect of the subsequent movements of individuals within the settlement habitat. Relationships of this kind may also appear in other fields of ecology.

Marine Biology, 2012

The brown shrimp Crangon crangon is a key species in the coastal areas of the North Sea. It const... more The brown shrimp Crangon crangon is a key species in the coastal areas of the North Sea. It constitutes a significant food source for fishes. Simultaneously, it is an important predator on a wide range of invertebrates. C. crangon shows a variety of digestive enzymes that allow to utilizing a wide range of food items. The initial step of alimentary protein digestion, that is the degradation into peptides, is facilitated by set of endopeptidases which are expressed by the midgut gland. In crustaceans, these endopeptidases are often dominated by serine proteinases. C. crangon, however, predominantly express cysteine proteinases, while only some specimens show a highly variable pattern of serine proteinases. The composition of these serine endopeptidases was investigated using liquid chromatography, substrate gel electrophoresis and inhibitor assays. Distinctly elevated activities were present only in about 10% of the samples. When activity was detected, two peaks, one with tryptic activity and the other one with chymotryptic activity, could be separated by anionic exchange chromatography. Moreover, specimens with elevated tryptic activities often showed highly polymorphic patterns of endopeptidases after electrophoretic separation. Overall, 30 different bands of endopeptidases were identified. There was no similarity between animals from the same sampling sites, neither between animals of similar size, weight or nutritive state. The polymorphism of proteinase from the midgut gland seems to reflect the high adaptive potential of this species to variable trophic conditions in a continuously changing environment.

Aquatic Biology, 2011

Marine invertebrate larvae suffer high mortality due to abiotic and biotic stress. In planktotrop... more Marine invertebrate larvae suffer high mortality due to abiotic and biotic stress. In planktotrophic larvae, mortality may be minimised if growth rates are maximised. In estuaries and coastal habitats however, larval growth may be limited by salinity stress, which is a key factor selecting for particular physiological adaptations such as osmoregulation. These mechanisms may be energetically costly, leading to reductions in growth. Alternatively, the metabolic costs of osmoregulation may be offset by the capacity maintaining high growth at low salinities. Here we attempted identify general response patterns in larval growth at reduced salinities by comparing 12 species of decapod crustaceans with differing levels of tolerance to low salinity and differing osmoregulatory capability, from osmoconformers to strong osmoregulators. Larvae possessing tolerance to a wider range in salinity were only weakly affected by low salinity levels. Larvae with a narrower tolerance range, by contrast, generally showed reductions in growth at low salinity. The negative effect of low salinity on growth decreased with increasing osmoregulatory capacity. Therefore, the ability to osmoregulate allows for stable growth. In euryhaline larval decapods, the capacity to maintain high growth rates in physically variable environments such as estuaries appears thus to be largely unaffected by the energetic costs of osmoregulation.

Ecology and Evolution, 2021

This is an open access article under the terms of the Creative Commons Attribution License, which... more This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Scientific Reports

Understanding biological responses to environmental fluctuations (e.g. heatwaves) is a critical g... more Understanding biological responses to environmental fluctuations (e.g. heatwaves) is a critical goal in ecology. Biological responses (e.g. survival) are usually measured with respect to different time reference frames, i.e. at specific chronological times (e.g. at specific dates) or biological times (e.g. at reproduction). Measuring responses on the biological frame is central to understand how environmental fluctuation modifies fitness and population persistence. We use a framework, based on partial differential equations (PDEs) to explore how responses to the time scale and magnitude of fluctuations in environmental variables (= drivers) depend on the choice of reference frame. The PDEs and simulations enabled us to identify different components, responsible for the phenological and eco-physiological effects of each driver on the response. The PDEs also highlight the conditions when the choice of reference frame affects the sensitivity of the response to a driver and the type of ...

Developmental Biology and Larval Ecology, 2020

This volume examines Developmental Biology and Larval Ecology, Chapters in this volume synthesize... more This volume examines Developmental Biology and Larval Ecology, Chapters in this volume synthesize our current understanding of early crustacean development from the egg through the embryonic and larval phase. The first part of this volume focuses on the fundamental aspects of crustacean embryonic development. The second part of the book provides an account of the larval phase of crustaceans and describes processes that influence the development from hatching to an adult-like juvenile. The third and final part of the book explores ecological interactions during the planktonic phase and how crustacean larvae manage to find food, navigate the dynamic water column, and avoid predators in a medium that offers few refuges. Collectively, these fifteen chapters provide a thorough overview of our present knowledge across the major themes in crustacean developmental biology and larval ecology. We expect this volume will be valuable to scholars and students who are interested in gaining deeper...

Ecography, 2020

Predicting range expansion of invasive species is one of the key challenges in ecology. We modell... more Predicting range expansion of invasive species is one of the key challenges in ecology. We modelled the phenological window for successful larval release and development (WLR) in order to predict poleward expansion of the invasive crab Hemigrapsus sanguineus along the Atlantic coast of North America and north Europe. WLR quantifies the number of opportunities (in days) when larval release leads to a successful completion of the larval phase; WLR depends on the effects of temperature on the duration of larval development and survival. Successful larval development is a necessary requirement for the establishment of self-persistent local populations. WLR was computed from a mechanistic model, based on in situ temperature time series and a laboratory-calibrated curve predicting duration of larval development from temperature. As a validation step, we checked that model predictions of the time of larval settlement matched observations from the field for our local population (Helgoland, North Sea). We then applied our model to the North American shores because larvae from our European population showed, in the laboratory, similar responses to temperature to those of a North American population. WLR correctly predicted the northern distribution limit in North American shores, where the poleward expansion of H. sanguineus appear to have stalled (as of 2015). For north Europe, where H. sanguineus is a recent invader, WLR predicted ample room for poleward expansion towards NE England and S Norway. We also explored the importance of year-to-year variation in temperature for WLR and potential expansion: variations in WLR highlighted the role of heat waves as likely promoters of recruitment subsidising sink populations located at the distribution limits. Overall, phenological windows may be used as a part of a warning system enabling more targeted programs for monitoring.

Helgoland Marine Research, 2003

Scientific reports, Jan 23, 2018

Marine crabs inhabit shallow coastal/estuarine habitats particularly sensitive to climate change,... more Marine crabs inhabit shallow coastal/estuarine habitats particularly sensitive to climate change, and yet we know very little about the diversity of their responses to environmental change. We report the effects of a rarely studied, but increasingly prevalent, combination of environmental factors, that of near-future pCO (~1000 µatm) and a physiologically relevant 20% reduction in salinity. We focused on two crab species with differing abilities to cope with natural salinity change, and revealed via physiological and molecular studies that salinity had an overriding effect on ion exchange in the osmoregulating shore crab, Carcinus maenas. This species was unaffected by elevated CO, and was able to hyper-osmoregulate and maintain haemolymph pH homeostasis for at least one year. By contrast, the commercially important edible crab, Cancer pagurus, an osmoconformer, had limited ion-transporting capacities, which were unresponsive to dilute seawater. Elevated CO disrupted haemolymph pH h...

Brazilian Journal of Oceanography, 2010

The seasonal dynamics of the fish community in the Pando estuary on the Uruguayan coast were stud... more The seasonal dynamics of the fish community in the Pando estuary on the Uruguayan coast were studied in relation to environmental sampled monthly between May 2002 and June 2003. Individuals collected were identified, and classified into stages (juveniles, adults) and functional groups. Relationships between community dynamics and environmental variables were evaluated using uni- and multivariate techniques. Twenty-one species, mostly freshwater stragglers, estuarine and marine migrants were collected. The most abundant species were Micropogonias furnieri, Mugil platanus, Paralichthys orbignyanus and Brevoortia aurea and were represented by juveniles. The community varied seasonally with rapid shifts in spring and autumn associated with changes in temperature and salinity. Significant correlations between abundance and temperature may be related to the timing of life cycle events. In this estuary, the salinity appears to play a key role in the functional structure and in the use of t...

Marine Ecology Progress Series, 2017

Journal of Plankton Research, 2014

We evaluate the potential for decapod larvae to develop under temporally limited daily access to ... more We evaluate the potential for decapod larvae to develop under temporally limited daily access to food across a broad thermal range. Larvae of the European lobster Homarus gammarus and velvet swimming crab Necora puber were successfully reared to juvenile and megalopa stages, respectively, at four temperatures (range 15-248C) under both permanent (24 h) and limited (4 h) daily access to prey. Survival was high in both species with no consistent effect of food limitation. Larvae developed faster with increasing temperature. Model selection indicated that limited access to food in N. puber slowed development from zoea III onwards by 10-25% depending on stage and temperature. Food limitation slowed development of H. gammarus in zoea III and stage IV by 6-30%, with significant interactions of food  temperature. Dry mass, carbon and nitrogen content of H. gammarus all decreased with temperature and were lower under limited access to food. Decapod larvae of the tested species show a high potential to survive and develop with a temporally patchy food resource, although a longer development and smaller body mass at the time of settlement may lead to fitness costs.