Biology subjects

Lindmark, M.

Publications and source records attributed to Lindmark, M..

12 recordsLinked to original sources

bioRxiv2026

Thermal niche warming is more consistent than range shifts in marine species under climate change

Marine species are widely expected to shift poleward or into deeper waters in response to rising ocean temperatures. However, our knowledge is primarily based on studies examining range shifts along single dimensions at a time (e.g., latitude or depth). Failing to address how movements along multiple dimensions interact, including associated changes in thermal exposure, may result in misleading conclusions and predictions of species distribution and community composition under global warming. To address this knowledge gap, we here develop and apply a multidimensional framework that jointly evaluates climate-driven redistribution of marine fish across latitude, longitude, depth and realized thermal niches, based on long-term scientific bottom-trawl surveys throughout the North Atlantic and Northeast Pacific. Our results show that net redistributions are generally small and highly region-specific, while the realized thermal niches of species have warmed substantially over the past three decades. These findings demonstrate that spatial redistribution is generally failing to keep pace with rising temperatures and challenge the prevailing assumption that marine species will move to escape warming. This has direct implications for biodiversity indicators that rely on distributional shifts as evidence of climate impacts, as well as climate-informed management and conservation of marine ecosystems, fisheries, and biodiversity at large.

ecology↗

bioRxiv2025

Reduced size of larvae and small fish linked to warming and reduced prey density

Body size is a integrative trait that has declined across ecological assemblages in the last decades. Changes in body size of early life stages and small-bodied fish are driven by complex interactions between size-dependent mortality, and temperature- and food dependent growth, and can have consequences for recruitment to the adult stock and food availability to predators. While the mechanisms can be difficult to disentangle using observational data alone, simple indicators such as mean size can provide important information about ecosystem conditions as oceans rapidly change. Using 30 years of observations from the IBTS-MIK ichthyoplankton survey in Skagerrak and Kattegat in combination with sea surface temperature data, we investigated changes in the body size of early life stages and small-bodied fishes for 10 commercial and non-commercial species using geostatistical mixed models, and trends in prey density using generalized additive models. We found positive associations between chlorophyll-a concentration and length in 8 species (3 significant), and negative associations between temperature and length in 9 species (4 significant). Standardized indices of length revealed negative trends over time for all species since 2010, and all species were smaller in 2024 compared to 2000. The decline in size since 2010 varied between 30%-1%, with a mean of 14% and 9% for species predominantly found in Skagerrak and Kattegat, respectively. The trend of decreased body sizes since 2010 coincides with rapid declines in Calanus spp. -- a key prey predicted to decline in this area at the edge of their distribution area due to climate change. In Skagerrak it also coincides with a decline in the density of large copepods (> 0.25 mm). The synchronous declines in larval size across taxonomically diverse species experiencing different rates of exploitation suggest a common response to changing environmental conditions, which could have cascading effects throughout marine food webs.

ecology↗

bioRxiv2025

Weak effects of local prey density and spatial overlap on predation intensity in a temperate marine ecosystem

Quantifying the impact of lower trophic level species abundance on higher trophic level predators (and vice versa) is critical for understanding marine ecosystem dynamics and for implementing ecosystem-based management. Trophic ecosystem models generally predict a tight coupling between prey and fish predators, such that higher abundance of lower trophic species increases abundance of higher trophic level predators. This assumes that predator feeding rates are limited by prey availability to some degree. Despite being a key component of predator-prey interactions and multi-species fisheries management, relatively few studies have assessed the impacts of prey availability on predation patterns of mobile, generalist fish predators using spatiotemporal models and local-scale stomach content, predator, and prey data. In this study, we explore the association between local density of key prey and predator stomach contents, and predator-prey spatiotemporal overlap and predation indices, using the Baltic Sea as a case study. We use three decades of spatially resolved biomass and stomach content data on Atlantic cod (Gadus morhua), and biomass data on three of its key prey: herring (Clupea harengus), the isopod Saduria entomon, and sprat (Sprattus sprattus). Using geostatistical generalized linear mixed effects models fitted to relative biomass density and prey-weight-per-predator-weight, we estimate spatiotemporal trends and annual indices of biomass weighted and area-expanded per-capita and population-level predation, predator-prey overlap, and the correlation between these indices. Range shifts have resulted in reduced predator-prey overlap over time, which is now the lowest in three decades. For Saduria, we find an association between prey availability and stomach contents, but not for herring or sprat. Similarly, only in Saduria do we find a positive correlation between population-level predation indices and the spatiotemporal overlap. Although behavioral interactions with pelagic prey are challenging to infer from stomach content and acoustic data due to high mobility leading to fine-scale spatiotemporal mismatch, the weak connection with local-scale availability, and low correlation between population-level predation and spatial overlap, could imply weaker coupling between pelagic prey and cod than previously thought. These findings provide key information on the strength of species interactions, which is crucial for the continued development of multispecies models and ecosystem-based fisheries management.

ecology↗

bioRxiv2024

Estimating scale-dependent covariate responses using two-dimensional diffusion derived from the SPDE method

O_LISpecies distribution models (SDMs) are widely used to standardize spatially unbalanced data, project climate impacts, and identify habitat for conservation. SDMs typically estimate the impact of local environmental conditions by estimating a dome-shaped or non-parametric "environmental response function". However, ecological responses often integrate across local habitat conditions, such that species density depends on habitat at the location of sampling but also at nearby locations. C_LIO_LITo address this, we extend methods from the Stochastic Partial Differential Equation (SPDE) method that is widely used in INLA, which approximates spatial correlations based on local diffusion over a finite-element mesh (FEM). We specifically introduce the sparse inverse-diffusion operator on a FEM, and apply this operator to covariates to efficiently calculate a spatially weighted average of local habitat that is then passed through pointwise basis-expansion to predict species densities. We show that this operator has several useful properties, i.e., conservation of mass, linear computational time with spatial resolution, and invariance to linear (scale and offset) transformations of covariates. C_LIO_LIWe test this covariate-diffusion method using a simulation experiment, and show that it can correctly recover a non-local environmental response while collapsing to a local (pointwise) response when warranted. We apply it to monitoring data for 25 bottom-associated fishes in the eastern Bering Sea and 20 bird species in the western United States. This application confirms that non-local responses in the eastern Bering Sea case study are parsimonious for 26 species-maturity combinations, while 18 collapse to the pointwise method. Estimates suggest that some species-maturity combinations avoid proximity to the continental slope, beyond what is predicted by local bathymetry in isolation. By contrast, in four of the 20 bird species is the diffused human population density covariate more parsimonious than the original covariate. C_LIO_LIThe covariate-diffusion method introduced here constitutes a fast and efficient approach to modelling non-local covariate effects. This flexible method may be useful in cases when covariates influence nearby population densities, for instance due to movement of the sampled species or its important biological or physical drivers. C_LI

ecology↗

bioRxiv2024

Quantifying competition between two demersal fish species from spatiotemporal stomach content data

Inference on competition is often made on indirect patterns of potential competition, such as population trends and spatiotemporal overlap in diet and distribution. However, these indicators do not test if the contested resources are limited in supply, nor if they decline as competitor biomass increases. Using stomach content and biomass data, we evaluate food competition between Atlantic cod (Gadus morhua) and flounder (Platichthys spp.) in the Baltic Sea. We quantify diet overlap and fit geostatistical mixed models to evaluate effects of local-scale covariates on stomach contents. The dietary overlap is low and does not decline with predator density. We find that cod feed less on the isopod Saduria entomon at high flounder densities. However, the total prey weight in cod is not affected by flounder densities. This suggests interspecific food competition is not limiting the overall feeding of cod, but affects its diet composition. In addition, we find support for intraspecific food competition in large cod and flounder. Our study illustrates the importance of local-scale processes when inferring competition from stomach content data.

ecology↗

bioRxiv2024

Non-linear growth-temperature relationship leads toopposite responses to warming in cold versus warmpopulations

Body size is a key functional trait that has declined in many biological communities, partly due to changes in individual growth rates in response to climate warming. However, our understanding of growth responses in natural ecosystems is limited by relatively short time series without large temperature contrasts and unknown levels of adaptation to local temperatures across populations. In this study, we collated back-calculated length-at-age data for the fish Eurasian perch (Perca fluviatilis) from 10 populations along the Baltic Sea coast between 1953-2015 (142023 length-at-age measurements). We fitted individual-level growth trajectories using the von Bertalanffy growth equation, and reconstructed local temperature time series using generalized additive models fitted to three data sources. Leveraging a uniquely large temperature contrast due to climate change and artificial heating, we then estimated population-specific and global growth-temperature relationships using Bayesian mixed models, and evaluated if they conformed to local adaption or not. We found little evidence for local adaptation in the temperature-dependence of individual growth curves. Instead, population-specific curves mapped onto a global curve, resulting in body growth increasing with warming in cold populations but decreasing in warm populations. Understanding to which degree the effects of warming on growth and size are population-specific is critical for generalizing predictions of climate impacts on growth, which is a key biological trait affecting multiple levels of biological organisation from individuals to ecosystem functioning.

ecology↗

bioRxiv2023

Assessing the overlap between fishing activities and chondrichthyans distribution exposes high-risk areas for bycatch of threatened species

Sharks, rays, and chimaeras (chondrichthyans) play a crucial role in marine ecosystem functioning but are highly vulnerable to fishing. Hence, understanding the spatial overlap between chondrichthyans and fishing effort is essential for effective conservation and management. Here, we propose an integrated approach that combines Vessel Monitoring System data with geostatistical species distribution models to assess the potential impact of fishing on chondrichthyan populations in the western Adriatic Sea. By mapping the overlap between model-based chondrichthyan distribution, species richness, and the proportion of threathened species with bottom trawl fishing activities, we identify areas at high risk for chondrichthyan bycatch. Our findings show that many of these species are at risk across a large part of their distribution within the study area. Notably, there is a substantial spatial overlap between regions where threatened chondrichthyans are found and species-rich areas with locations of intensive bottom trawl fishing in the northern and central offshore regions of the western Adriatic, emphasizing the vulnerability of these species to fishing pressure. Furthermore, differences in overlap between distinct fishing gears highlight the importance of considering specific fishing practices when formulating management strategies. While our work provides novel insights to potential bycatch hotspots, limitations related to data sources, spatial resolution, and the inability to directly quantify fishing impacts should be considered. Nonetheless, our findings contribute to the development of targeted conservation and spatial management measures, offering a general approach to study model-based spatial hotspots aimed at protecting and sustaining chondrichthyan populations in the heavily exploited Adriatic Sea.

ecology↗

bioRxiv2022

Evaluating drivers of spatiotemporal individual condition of a bottom-associated marine fish

An organisms body condition describes its mass given its length and is often positively associated with fitness. The condition of Atlantic cod (Gadus morhua) in the Baltic Sea has declined dramatically since the early 1990s, possibly due to increased competition, food limitation, and hypoxia. However, the effect of biotic and abiotic variables on body condition have not been evaluated at local scales, which is important given spatial heterogeneity. We evaluate changes in distribution, experienced environmental conditions, and individual-level condition of cod in relation to covariates at different spatial scales using geostatistical models with spatial and spatiotemporal random effects. Oxygen, sprat biomass, and temperature were positively related to condition, and depth negatively associated, but the effect sizes of these variables were small--spatial and spatiotemporal latent variables explained almost five times more variation than fixed effects. We also show that accounting for the heterogenous distribution of cod leads to both lover levels and steeper trends over time in experienced oxygen compared to those in the environment. Understanding the drivers of spatiotemporal variation in body condition is critical for predicting responses to environmental change and to effective fishery management; yet low explanatory power of covariates on individual condition constitutes a major challenge.

ecology↗

bioRxiv2022

Larger but younger fish when growth compensates for higher mortality in heated ecosystem

Ectotherms are predicted to "shrink" with global warming, in line with general growth models and the temperature-size rule (TSR), both predicting smaller adult sizes with warming. However, they also predict faster juvenile growth rates and thus larger size-at-age of young organisms. Hence, the result of warming on the size-structure of a population depends on the interplay between how mortality rate, juvenile- and adult growth rates are affected by warming. Here, we use two-decade long time series of biological samples from a unique enclosed bay heated by cooling water from a nearby nuclear power plant to become 5-10 {degrees}C warmer than its reference area. We used growth-increment biochronologies (12658 reconstructed length-at-age estimates from 2426 individuals) to quantify how >20 years of warming has affected body growth and size-at-age and catch data to quantify mortality rates and population size- and age structure of Eurasian perch (Perca fluviatilis). In the heated area, growth rates were faster for all sizes, and hence size-at-age was larger for all ages, compared to the reference area. While mortality rates were also higher (lowering mean age by 0.4 years), the faster growth rates lead to a 2 cm larger mean size in the heated area. Differences in the size-spectrum exponent (describing the proportion of fish by size) were less clear statistically. Our analyses reveal that mortality, in addition to plastic growth and size-responses, is a key factor determining the size structure of populations exposed to warming. Understanding the mechanisms by which warming affects the size- and age structure of populations is critical for predicting the impacts of climate change on ecological functions, interactions, and dynamics.

ecology↗

bioRxiv2021

Bottom-up and top-down effects of temperature on body growth, population size spectra and yield in a size-structured food web

Resolving the combined effect of climate warming and exploitation in a food web context is key for predicting future biomass production, size-structure, and potential yields of marine fishes. Previous studies based on mechanistic size-based food web models have found that bottom-up processes are important drivers of size-structure and fisheries yield in changing climates. However, we know less about the joint effects of bottom-up and physiological effects of temperature; how do temperature effects propagate from individual-level physiology through food webs and alter the size-structure of exploited species in a community? Here we assess how a species-resolved size-based food web is affected by warming through both these pathways, and by exploitation. We parameterize a dynamic size spectrum food web model inspired by the offshore Baltic Sea food web, and investigate how individual growth rates, size-structure, relative abundances of species and yields are affected by warming. The magnitude of warming is based on projections by the regional coupled model system RCA4-NEMO and the RCP 8.5 emission scenario, and we evaluate different scenarios of temperature dependence on fish physiology and resource productivity. When accounting for temperature-effects on physiology in addition to on basal productivity, projected size-at-age in 2050 increases on average for all fish species, mainly for young fish, compared to scenarios without warming. In contrast, size-at-age decreases when temperature affects resource dynamics only, and the decline is largest for young fish. Faster growth rates due to warming, however, do not always translate to larger yields, as lower resource carrying capacities with increasing temperature tend to result in declines in the abundance of larger fish and hence spawning stock biomass. These results suggest that to understand how global warming affects the size structure of fish communities, both direct metabolic effects and indirect effects of temperature via basal resources must be accounted for.

ecology↗

bioRxiv2021

Optimum growth temperature declines with body size within fish species

According to the temperature-size rule, warming of aquatic ecosystems is generally predicted to increase individual growth rates but reduce asymptotic body sizes of ectotherms. However, we lack a comprehensive understanding of how growth and key processes affecting it, such as consumption and metabolism, depend on both temperature and body mass within species. This limits our ability to inform growth models, link experimental data to observed growth patterns, and advance mechanistic food web models. To examine the combined effects of body size and temperature on individual growth, as well as the link between maximum consumption, metabolism and body growth, we conducted a systematic review and compiled experimental data on fishes from 52 studies that combined body mass and temperature treatments. By fitting hierarchical models accounting for variation between species, we estimated how maximum consumption and metabolic rate scale jointly with temperature and body mass within species. We found that whole-organism maximum consumption increases more slowly with body mass than metabolism, and is unimodal over the full temperature range, which leads to the prediction that optimum growth temperatures decline with body size. Using an independent dataset, we confirmed this negative relationship between optimum growth temperature and body size. Small individuals of a given population may therefore exhibit increased growth with initial warming, whereas larger conspecifics could be the first to experience negative impacts of warming on growth. These findings help advance mechanistic models of individual growth and food web dynamics and improve our understanding of how climate warming affects the growth and size structure of aquatic ectotherms.

ecology↗

bioRxiv2018

Size-based ecological interactions drive food web responses to climate warming

Predicting the impacts of climate change on animal populations and communities requires understanding of feedbacks between direct physiological responses and indirect effects via ecological interactions. Food-dependent body growth and within-species size variation have major effects on dynamics of populations and communities through feedbacks between individual performance and population size structure. Moreover, evidence suggests a link between temperature and population size structure, but we lack an understanding of how this is mediated by species interactions when life history processes are food-dependent. Here, we use a dynamic stage-structured biomass model with food-, size- and temperature-dependent life history processes to assess how temperature affects coexistence, stability and size structure in a tri-trophic food chain. We show that predator biomass densities decline with warming either gradually or in the form of collapses, depending on which consumer life stage they predominantly feed on. Collapses occur when warming destabilizes the community and induces alternative stable states via Allee effects, which emerge when predators promote their own food source through predation. By contrast, warming at low temperatures stabilizes the community as limit cycles turn to fixed point dynamics, unless predators feed only on juveniles. Elevated costs of being large in warmer environments accelerate the decline in predator persistence and mean body size of the community. These results suggest that predator persistence in warmer climates may be lower than previously acknowledged when accounting for size- and food-dependence of life history processes, and that interactions within and between species can mediate the effects of warming on food web stability.\n\nSignificanceClimate warming is altering the dynamics and structure of aquatic ecosystems worldwide. Predicting food web reorganization under rising temperatures requires an understanding of physiological responses and ecological interactions of organisms, both of which depend on body size. We show that size variation within species, food-dependent growth and ecological interactions critically affect how food chains respond to warming. Specifically, warming can stabilize or destabilize food chains and expose predators to increased risk of sudden collapses, resulting in alternative stable food web states. Increasing temperatures can cause abrupt reductions in mean community body size, primarily due to loss of top predators. The potential loss of biodiversity and shifts in ecosystem stability are among the major challenges caused by a warming climate.

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