Santi Alvarez

Global climate change ecology

Assessing long-term changes in marine communities spanning from arctic to temperate ecosystems with a variety of statistical techniques combining GIS, ordination methods, generalized linear modelling, additive modelling, and time-series analysis.

Plankton ecology

Exploring the connections among geohemical cycles, plankton communities, and fish from a global change perspective. These articles analyse both data obtained with both monitoring and experimental approaches, and use complex modelling techniques both linear and non-linear.

Social-ecological systems and local perceptions of climate change

Analysing the effects of global change in social-ecological systems. These include data obtained with interview and survey approaches, and use regression modelling and network analyses to disentangle the perception and effect of climate on different communities.

Editorial work

Apart from the typical editorial work involved in academic collaborations, I have contributed as editor in the following work

Global Climate Change Ecology

Temporal changes in plankton of the North Sea: community shifts and environmental drivers

Santiago Alvarez-Fernandez, Han Lindeboom, Erik Meesters

This paper analyses long-term and seasonal changes in the North Sea plankton community during the period 1970 to 2008. Based on Continuous Plankton Recorder (CPR) data covering 38 yr, major changes in both phytoplankton and zooplankton abundance and community structure were identified. Regime changes were detected around 1978, 1989 and 1998. The first 2 changes have been discussed in the literature and are defined as a cold episodic event (1978) and a regime shift towards a warm dynamic regime (1989). The effect of these 2 regime changes on plankton indicators was assessed and checked against previous studies. The 1998 change represents a shift in the abundance and seasonal patterns of dinoflagellates and the dominant zooplankton group, the neritic copepods. Furthermore, environmental factors such as air temperature, wind speed and the North Atlantic water inflow were identified as potential drivers of change in seasonal patterns, and the most-likely environmental causes for detected changes were assessed. We suggest that a change in the balance of dissolved nutrients driven by these environmental factors was the cause of the latest change in plankton community structure, which in turn could have affected the North Sea fish community.

Global Climate Change Ecology

Effect of zooplankton on fish larval abundance and distribution: a long-term study on North Sea herring (Clupea harengus)

S. Alvarez-Fernandez, P. Licandro, C. J. G. van Damme, and M. Hufnagl

During the last decade, North Sea autumn spawning herring (Clupea harengus) has gone through consecutive years of low recruitment despite high spawning-stock biomass. Although several mechanisms, such as reduced larval growth and high early larvae mortality, have been identified as co-occurring during these years, the causes behind them have not been identified. In this study, we analyse a long-term dataset of larval distribution, obtained during the International Bottom Trawl Survey, in relation to environmental conditions during winter and zooplankton abundances, obtained from the continuous plankton recorder. These analyses assessed the potential influence of these factors on the reduced survival of larval stages. Generalized additive mixed models on 30 years of data showed the abundance of Pseudocalanus sp. during winter to have a strong relationship with larval distribution and abundance, suggesting that predator–prey processes are behind the low recruitment in recent years. According to our models, the direct effect of temperature on larval abundances was less than the effect of zooplankton abundances.

Global Climate Change Ecology

Plankton responses to ocean acidification: The role of nutrient limitation

S. Alvarez-Fernandez, L.T. Bach, J. Taucher, U. Riebesell, U. Sommer, N. Aberle, C.P.D. Brussaard, M. Boersma

In situ mesocosm experiments on the effect of ocean acidification (OA) are an important tool for investigating potential OA-induced changes in natural plankton communities. In this study we combined results from various in-situ mesocosm studies in two different ocean regions (Arctic and temperate waters) to reveal general patterns of plankton community shifts in response to OA and how these changes are modulated by inorganic nutrient availability. Overall, simulated OA caused an increase in phytoplankton standing stock, which was more pronounced in smaller-sized taxa. This effect on primary producers was channelled differently into heterotroph primary consumers depending on the inorganic nutrient availability. Under limiting conditions, bacteria and micro-heterotrophs benefited with inconsistent responses of larger heterotrophs. During nutrient replete periods, heterotrophs were in general negatively affected, although there was an increase of some mesozooplankton developmental stages (i.e. copepodites). We hypothesize that changes in phytoplankton size distribution and community composition could be responsible for these food web responses.

Global Climate Change Ecology

Antarctic phytoplankton community composition and size structure: importance of ice type and temperature as regulatory factors

T. E. G. Biggs, S. Alvarez‑Fernandez, C. Evans, K. D. A. Mojica, P. D. Rozema, H. J. Venables, D. W. Pond, C. P. D. Brussaard

Climate change at the Western Antarctic Peninsula (WAP) is predicted to cause major changes in phytoplankton community composition, however, detailed seasonal field data remain limited and it is largely unknown how (changes in) environmental factors influence cell size and ecosystem function. Physicochemical drivers of phytoplankton community abundance, taxonomic composition and size class were studied over two productive austral seasons in the coastal waters of the climatically sensitive WAP. Ice type (fast, grease, pack or brash ice) was important in structuring the pre-bloom phytoplankton community as well as cell size of the summer phytoplankton bloom. Maximum biomass accumulation was regulated by light and nutrient availability, which in turn were regulated by wind-driven mixing events. The proportion of larger-sized (> 20 µm) diatoms increased under prolonged summer stratification in combination with frequent and moderate-strength wind-induced mixing. Canonical correspondence analysis showed that relatively high temperature was correlated with nano-sized cryptophytes, whereas prymnesiophytes (Phaeocystis antarctica) increased in association with high irradiance and low salinities. During autumn of Season 1, a large bloom of 4.5-µm-sized diatoms occurred under conditions of seawater temperature > 0 °C and relatively high light and phosphate concentrations. This bloom was followed by a succession of larger nano-sized diatoms (11.4 µm) related to reductions in phosphate and light availability. Our results demonstrate that flow cytometry in combination with chemotaxonomy and size fractionation provides a powerful approach to monitor phytoplankton community dynamics in the rapidly warming Antarctic coastal waters.

Global Climate Change Ecology

Simulated ocean acidification reveals winners and losers in coastal phytoplankton

Lennart T. Bach, Santiago Alvarez-Fernandez, Thomas Hornick, Annegret Stuhr, Ulf Riebesell

The oceans absorb ~25% of the annual anthropogenic CO2 emissions. This causes a shift in the marine carbonate chemistry termed ocean acidification (OA). OA is expected to influence metabolic processes in phytoplankton species but it is unclear how the combination of individual physiological changes alters the structure of entire phytoplankton communities. To investigate this, we deployed ten pelagic mesocosms (volume ~50 m3) for 113 days at the west coast of Sweden and simulated OA (pCO2 = 760 μatm) in five of them while the other five served as controls (380 μatm). We found: (1) Bulk chlorophyll a concentration and 10 out of 16 investigated phytoplankton groups were significantly and mostly positively affected by elevated CO2 concentrations. However, CO2 effects on abundance or biomass were generally subtle and present only during certain succession stages. (2) Some of the CO2-affected phytoplankton groups seemed to respond directly to altered carbonate chemistry (e.g. diatoms) while others (e.g. Synechococcus) were more likely to be indirectly affected through CO2 sensitive competitors or grazers. (3) Picoeukaryotic phytoplankton (0.2–2 μm) showed the clearest and relatively strong positive CO2 responses during several succession stages. We attribute this not only to a CO2 fertilization of their photosynthetic apparatus but also to an increased nutrient competitiveness under acidified (i.e. low pH) conditions. The stimulating influence of high CO2/low pH on picoeukaryote abundance observed in this experiment is strikingly consistent with results from previous studies, suggesting that picoeukaryotes are among the winners in a future ocean.

Plankton Ecology

Toxic algal bloom induced by ocean acidification disrupts the pelagic food web

Ulf Riebesell, Nicole Aberle-Malzahn, Eric P. Achterberg, María Algueró-Muñiz, Santiago Alvarez-Fernandez, et al.

Ocean acidification, the change in seawater carbonate chemistry due to the uptake of anthropogenic CO2, affects the physiology of marine organisms in multiple ways. Diverse competitive and trophic interactions transform the metabolic responses to changes in community composition, seasonal succession and potentially geographical distribution of species. The health of ocean ecosystems depends on whether basic biotic functions are maintained, ecosystem engineers and keystone species are retained, and the spread of nuisance species is avoided. Here, we show in a field experiment that the toxic microalga Vicicitus globosus has a selective advantage under ocean acidification, increasing its abundance in natural plankton communities at CO2 levels higher than 600 µatm and developing blooms above 800 µatm CO2. The mass development of V. globosus has had a dramatic impact on the plankton community, preventing the development of the micro- and mesozooplankton communities, thereby disrupting trophic transfer of primary produced organic matter. This has prolonged the residence of particulate matter in the water column and caused a strong decline in export flux. Considering its wide geographical distribution and confirmed role in fish kills, the proliferation of V. globosus under the IPCC CO2 emission representative concentration pathway (RCP4.5 to RCP8.5) scenarios may pose an emergent threat to coastal communities, aquaculture and fisheries.

Plankton Ecology

Chlorophyll in North Sea coastal and offshore waters does not reflect long term trends of phytoplankton biomass

Santiago Alvarez-Fernandez, Roel Riegman

This study analyses long-term and seasonal changes of phytoplankton community Carbon: Chlorophyll a ratio (θ) during the period 1991 to 2010 in North Sea waters and its relationship to environmental drivers. Based on the data from the Dutch water monitoring programme covering 20 years, major trends in phytoplankton abundance, community structure and chlorophyll were identified. Overall C:Chla increased during the study period, particularly in coastal areas. This increase was related to an increase in average underwater photosynthetically active radiation (PAR) and a decrease in nutrient concentrations. A mismatch was detected between chlorophyll a and biomass carbon trends caused by both a decrease in chlorophyll a values and an increase in biomass. In coastal waters, physiological adaptation to higher light and lower nutrient levels may have enhanced the θ, increasing from yearly averages of 12 g C ∗ g Chl a− 1 in 1990 to 69 g C ∗ g Chl a− 1 in 2010. Offshore, the increased stratification coincided with a shift towards dinoflagellate dominance. This dominance of dinoflagellates co-occurred with an increased θ yearly averages from 62 g C ∗ g Chl a− 1 in 1991 to 119 g C ∗ g Chl a− 1 in 2010. Because of these changes detected in C:Chl a ratio of multispecies phytoplankton communities, we question the validity of chlorophyll a as a proxy for phytoplankton biomass and argue its possible misrepresentation of phytoplankton dynamics.

Plankton Ecology

The craving for phosphorus in heterotrophic dinoflagellates and its potential implications for biogeochemical cycles

Cédric L. Meunier, Santiago Alvarez-Fernandez, Alessandra Ö. Cunha-Dupont, Carla Geisen, Arne M. Malzahn, Maarten Boersma, Karen H. Wiltshire

By altering the nutritional quality of primary producers, nutrient availability indirectly influences herbivores’ population dynamics. In turn, the resulting relationship between diet, growth, and wastes has consequences for nutrient cycling at the ecosystem level. We studied the link between dinoflagellates nutritional requirements and feeding behavior, and its influence on nutrient cycling. We show that long-term shifts in dissolved PO4 concentration in the North Sea are closely linked to biomass trends of heterotrophic dinoflagellates and support this observation with experimental data indicating particularly high phosphorus requirements in dinoflagellates. At the seasonal scale, we observe a negative correlation between natural dinoflagellate abundances and the concentration of dissolved P, and we estimate that, in spring, up to 30% of dissolved P can end up in microzooplankton biomass. Our study highlights that accounting for organismal metabolic requirement provides significant insight in interpreting and predicting nutrient cycles at the ecosystem level.

Plankton Ecology

Effects of warming rate, acclimation temperature and ontogeny on the critical thermal maximum of temperate marine fish larvae

Marta Moyano, Caroline Candebat, Yannick Ruhbaum, Santiago Álvarez-Fernández, Guy Claireaux, José-Luis Zambonino-Infante, Myron A. Peck

Most of the thermal tolerance studies on fish have been performed on juveniles and adults, whereas limited information is available for larvae, a stage which may have a particularly narrow range in tolerable temperatures. Moreover, previous studies on thermal limits for marine and freshwater fish larvae (53 studies reviewed here) applied a wide range of methodologies (e.g. the static or dynamic method, different exposure times), making it challenging to compare across taxa. We measured the Critical Thermal Maximum (CTmax) of Atlantic herring (Clupea harengus) and European seabass (Dicentrarchus labrax) larvae using the dynamic method (ramping assay) and assessed the effect of warming rate (0.5 to 9°C h-1) and acclimation temperature. The larvae of herring had a lower CTmax (lowest and highest values among 222 individual larvae, 13.1–27.0°C) than seabass (lowest and highest values among 90 individual larvae, 24.2–34.3°C). At faster rates of warming, larval CTmax significantly increased in herring, whereas no effect was observed in seabass. Higher acclimation temperatures led to higher CTmax in herring larvae (2.7 ± 0.9°C increase) with increases more pronounced at lower warming rates. Pre-trials testing the effects of warming rate are recommended. Our results for these two temperate marine fishes suggest using a warming rate of 3–6°C h-1: CTmax is highest in trials of relatively short duration, as has been suggested for larger fish. Additionally, time-dependent thermal tolerance was observed in herring larvae, where a difference of up to 8°C was observed in the upper thermal limit between a 0.5- or 24-h exposure to temperatures >18°C. The present study constitutes a first step towards a standard protocol for measuring thermal tolerance in larval fish.

Plankton Ecology

Exploring the microzooplankton–ichthyoplankton link: a combined field and modeling study of Atlantic herring (Clupea harengus) in the Irish Sea

Franziska Bils,  Marta Moyano,  Nicole Aberle,  Marc Hufnagl,  Santiago Alvarez-Fernandez,  Myron A. Peck

The microzooplankton–ichthyoplankton link remains poorly resolved in field studies due to a lack of simultaneous sampling of these predators and potential prey. This study compared the abundance, distribution and growth of larval Atlantic herring (Clupea harengus) and the abundance, biomass and composition of micro- and small mesozooplankton throughout the Irish Sea in November 2012 and 2013. In contrast to warmer months, microzooplankton biomass was highest in eastern areas, in the vicinity of the main spawning grounds of herring. Although the protozoan composition differed somewhat between years, dinoflagellates (e.g. Gymnodinium spp., Protoperidinium spp., Ceratium furca) dominated in abundance and/or biomass, similar to other temperate shelf seas in autumn/winter. Spatial differences in the protozoan community were strongly related to hydrographic characteristics (temperature, salinity). Significant relationships between the abundance of larval herring and dinoflagellates (positive) and copepodites (negative) suggested that complex grazing dynamics existed among lower trophic levels. When different, in situ size fractions of zooplankton were used as prey in a larval herring individual-based model, simulations that omitted protozooplankton under-predicted observed (biochemically-based) growth of 8–18 mm larvae. This study suggests that small planktonic organisms (20–300 µm) should be routinely surveyed to better understand factors affecting larval fish feeding, growth and survival.

Plankton Ecology

Rhyme and Reason: Plankton Changes in the North Sea Ecosystem

Santiago Alvarez Fernandez

As a result of natural and human induced pressures, marine ecosystems exhibit continuous changes in production, biomass and species composition. A major challenge is to distinguish between natural or non-manageable drivers and anthropogenic or manageable drivers like fisheries or sand extraction. The first step towards this distinction involves understanding natural changes of marine ecosystems, the spatial scale at which they take place and their potential recurrent patterns in time. Large scale engineering initiatives like Building with Nature need to understand the current state of marine ecosystems which they will become part of in order to make the best use of their resources without deteriorating their resilience and responses to natural environmental changes. This deep understanding of the ecosystem is a prerequisite to balance the sustainable functioning of ecosystems with the demand for development and use.

Social-ecological systems and local perceptions of climate change

Local indicators of climate change impacts described by indigenous peoples and local communities: Study protocol

Victoria Reyes-García, Santiago Álvarez-Fernández, Petra Benyei, David García-del-Amo, André B. Junqueira, Vanesse Labeyrie, Xiaoyue Li, Vincent Porcher, Anna Porcuna-Ferrer, Anna Schlingmann, Ramin Soleymani

In the quest to improve the understanding of climate change impacts on elements of the atmospheric, physical, and life systems, scientists are challenged by the scarcity and uneven distribution of grounded data. Through their long history of interaction with the environment, Indigenous Peoples and local communities have developed complex knowledge systems that allow them to detect impacts of climate change in the local environment. The study protocol presented here is designed 1) to inventory climate change impacts on the atmospheric, physical, and life systems based on local knowledge and 2) to test hypotheses on the global spatial, socioeconomic, and demographic distribution of reported impacts. The protocol has been developed within the framework of a project aiming to bring insights from Indigenous and local knowledge systems to climate research

Social-ecological systems and local perceptions of climate change

“So many things have changed”: Situated understandings of climate change impacts among the Bassari, south-eastern Senegal

Anna Porcuna-Ferrer, Laura Calvet-Mir, Théo Guillerminet, Santiago Alvarez-Fernandez, Vanesse Labeyrie, Eva Porcuna-Ferrer, Victoria Reyes-García

Mainstream discourses frame anthropogenic climate change as a biophysical apolitical problem, thus privileging Western science and silencing other worldviews. Through a case study among the Bassari, an ethnic group in South-Eastern Senegal, we assess the local, embodied, and situated understandings of climate change and the tensions that arise when the apolitical global climate change discourse interacts with situated understandings. Drawing on data from 47 semi-structured interviews and 176 surveys, we find that while the global climate change discourse has not permeated into the Bassari, they experience climate change through its many impacts on the biophysical and socio-economic systems. Results also highlight that climate is not considered the main or only driver of change, but that changes in elements of the climate system are inextricably linked with political and economic dynamics and environmental degradation. Finally, our results point toward the importance of values and supernatural forces in defining situated ways of conceptualizing, interpreting, and responding to change. By including situated worldviews in theoretical understandings of climate and environmental change, we contribute to the claims about the need to reframe how climate change is conceptualized. Our research emphasizes the importance of a relational view of climate change, which requires moving beyond understanding isolated climate change impacts towards defining climate change as a systemic problem. Building on feminist and decolonial literature, we argue for the need for more plural and democratic ways of thinking about climate change, crossing epistemological and ontological boundaries and including local communities and their knowledge and understandings.

Social-ecological systems and local perceptions of climate change

Crop biocultural traits shape seed networks: Implications for social-ecological resilience in south eastern Senegal

Anna Porcuna-Ferrer, Vanesse Labeyrie, Santiago Alvarez-Fernandez, Laura Calvet-Mir, Ndèye Fatou Faye, Sarah Ouadah, Victoria Reyes-García

Agroecosystems’ social-ecological resilience largely depends on the crop diversity generated and maintained by farmers, which provides insurance against changing environmental and socio-economic conditions. In turn, crop diversity generation, maintenance, and distribution is influenced by seed circulation networks. Thus, patterns of seed circulation can support or constrain households’ access to crop diversity, affecting on-farm crop diversity.

Social-ecological systems and local perceptions of climate change

A synthesis of women’s participation in small-scale fisheries management: why women’s voices matter

Mouna Chambon, Sara Miñarro, Santiago Alvarez Fernandez, Vincent Porcher, Victoria Reyes‑Garcia, Huran Tonalli Drouet, Patrizia Ziveri

While women globally make up nearly half of the fisheries workforce, their contribution to the sector has long been overlooked with implications for fisheries management. To assess women’s participation in small-scale fisheries (SSF) management and related socio-cultural, environmental, and economic impacts, we conducted a systematic review of peer-reviewed literature (n = 124 case studies). Women had no or limited participation in more than 80% of the examined case studies reporting their participation level in SSF management. Women’s exclusion from SSF management resulted in negative outcomes, whereas their active participation was associated with various positive impacts at multiple scales. Most of the documented impacts were socio-cultural, suggesting a gap in documenting environmental impacts stemmed from women’s participation in SSF management. Importantly, most impacts reported affected the social-ecological system scale, suggesting that gender inclusion may contribute to improving the management of SSF social-ecological systems. We conclude by highlighting the need to foster gender perspectives in data collection methods used in fisheries research, in SSF management, and in ecological research on SSF social-ecological systems.

Social-ecological systems and local perceptions of climate change

Understanding climate change impacts on Indigenous Peoples and local communities: A global perspective from local studies

Victoria Reyes-García, Santiago Álvarez-Fernández, Petra Benyei, Laura Calvet-Mir, Mouna Chambon, David García-del-Amo, André B. Junqueira, Xiaoyue Li, Vincent Porcher, Anna Porcuna-Ferrer, Anna Schlingmann, Ramin Soleymani, Adrien Tofighi-Niaki

Indigenous Peoples and local communities directly experience climate change impacts, but each group experiences impacts in a different way. The LICCI network includes about 50 Indigenous and non-Indigenous researchers working with and affiliated with the institutions around the world. The common ground of the network is a shared interest in exploring the diverse ways in which the climate change affects Indigenous Peoples and the local communities and how they respond to it. All members of the network also gratefully acknowledge and deeply respect the invaluable contributions of the Indigenous Peoples and local communities, whose traditional knowledge and practices have formed the foundation of this research. Overall, Indigenous Peoples and local communities’ understandings of change provide a holistic, multi-causal, and multi-scalar complex picture of the relations between the humans and the environment, entangling ecological observations with socio-economic, cultural and political critiques.

Social-ecological systems and local perceptions of climate change

Indigenous Peoples and local communities report ongoing and widespread climate change impacts on local social-ecological systems

Victoria Reyes-García, David García-del-Amo, Santiago Álvarez-Fernández, et al.

The effects of climate change depend on specific local circumstances, posing a challenge for worldwide research to comprehensively encompass the diverse impacts on various local social-ecological systems. Here we use a place-specific but cross-culturally comparable protocol to document climate change indicators and impacts as locally experienced and analyze their distribution. We collected first-hand data in 48 sites inhabited by Indigenous Peoples and local communities and covering all climate zones and nature-dependent liveli-hoods. We documented 1,661 site-agreed reports of change corresponding to 369 indicators.

Reports of change vary according to climate zone and livelihood activity. We provide compelling evidence that climate change impacts on Indigenous Peoples and local communities are ongoing, tangible, widespread, and affect multiple elements of their social-ecological systems. Beyond potentially informing contextualized adaptation plans, our results show that local reports could help identify economic and non-economic loss and damage related to climate change impacts suffered by Indigenous Peoples and local communities.

Editorial work

Routledge Handbook of Climate Change Impacts on Indigenous Peoples and Local Communities

Victoria Reyes-García

This Handbook examines the diverse ways in which climate change impacts Indigenous Peoples and local communities and considers their response to these changes.

While there is well-established evidence that the climate of the Earth is changing, the scarcity of instrumental data oftentimes challenges scientists’ ability to detect such impacts in remote and marginalized areas of the world or in areas with scarce data. Bridging this gap, this Handbook draws on field research among Indigenous Peoples and local communities distributed across different climatic zones and relying on different livelihood activities, to analyse their reports of and responses to climate change impacts. It includes contributions from a range of authors from different nationalities, disciplinary backgrounds, and positionalities, thus reflecting the diversity of approaches in the field. The Handbook is organised in two parts: Part I examines the diverse ways in which climate change – alone or in interaction with other drivers of environmental change – affects Indigenous Peoples and local communities; Part II examines how Indigenous Peoples and local communities are locally adapting their responses to these impacts. Overall, this book highlights Indigenous and local knowledge systems as an untapped resource which will be vital in deepening our understanding of the effects of climate change.

Photography credits:

Home: Osman Arabacı

Projects: Ahadi Muyal, Ganta Srinivas

Publications: Pixabay, Egor Kamelev, Andrea Schettino, Felix Rottmann

Contact: Jan Van der Wolf