Latitudinal consistency of biomass size spectra - benthic resilience despite environmental, taxonomic and functional trait variability

Abstract

Global warming is expected to cause reductions in organism body size, a fundamental biological unit important in determining biological processes. Possible effects of increasing temperature on biomass size spectra in coastal benthic communities were investigated. We hypothesized higher proportions of smaller size classes in warmer conditions. Soft bottom infauna samples were collected in six norwegian and Svalbard fjords, spanning wide latitudinal (60-81°N) and bottom water temperature gradients (from −2 to 8 °C). Investigated fjords differed in terms of environmental settings (e.g., pigments or organic carbon in sediments). The slopes of normalised biomass size spectra (NBSS) did not differ among the fjords, while the benthic biomass and NBSS intercepts varied and were related to chlorophyll a and δ 13 c in sediments. the size spectra based on both abundance and biomass remained consistent, regardless of the strong variability in macrofauna taxonomic and functional trait composition. Variable relationships between temperature and body size were noted for particular taxa. our results indicate that while benthic biomass depends on the nutritional quality of organic matter, its partitioning among size classes is consistent and independent of environmental and biological variability. the observed size structure remains a persistent feature of studied communities and may be resilient to major climatic changes. Body size is a fundamental biological characteristic that determines basic life-processes of organisms, including metabolic rate, generation time or locomotion speed 1. In multispecies assemblages, size structure can define species interactions, including position in food webs, and pathways and magnitudes of carbon flow through the system components 2,3. In aquatic studies, size spectra, i.e., abundance or biomass distribution among size classes 4,5 , are frequently assessed for communities, since such structural organization may have stronger implications for functionality than commonly reported taxonomic composition, diversity or abundance 6. The knowledge about the size distribution of organisms in the ecosystem may be useful not only as its descriptor but also as a basis for size-based ecosystem modelling to assess eco-evolutionary processes or possible consequences of environmental transformations due to human-induced changes 7. Yool et al. 8 incorporated knowledge of benthic biomass partitioning among size classes in modelling and in predictions concerning possible changes in the shelf and deep-sea ecosystems and forecasted a substantial decline of deep-sea benthic communities biomass (−32%) in future scenario of high greenhouse gas emissions. Size spectra may be powerful indicators of ecosystem functioning (e.g., productivity) and environmental changes (e.g., anthropogenic disturbances) 9,10. Despite their widespread and growing use in pelagic studies, size spectra remain rarely explored in marine benthos, mostly due to methodological difficulties and time consuming laboratory sample processing (measurem...

Will shrinking body size and increasing species diversity of crustaceans follow the warming of the Arctic littoral?

“…That is why the temperature increase due to global warming is likely to cause a change in average individual size, or selection toward smaller species in communities (Atkinson & Sibly, 1997). Such a pattern has already been demonstrated in pelagic Copepoda (Beaugrand, Ibanez, & Reid, 2000), but it is not yet universal in benthic communities (Mazurkiewicz, Górska, Renaud, & Włodarska‐Kowalczuk, 2020). The blurred size pattern among soft‐bottom benthos is due to the dominance of polychaete worms and bivalves—two groups in which linear growth is difficult to assess.…”

Spatiotemporal variability of abundance size-spectra in streams across North America

“…In contrast, Dossena et al (2012) found that slopes declined with temperature, but the effect varied over seasons. Mazurkiewicz et al (2020) found no relationship between marine benthic size spectra and temperatures in arctic systems. These contrasting outcomes, derived from different experimental approaches, generate uncertainty in how size spectra slopes should scale with temperature across large spatial gradients.…”

“…Size spectra are one of the few well documented organizing principles in ecology. A large body of literature has demonstrated the consistency of size-spectra relationships in diverse ecosystems (Jennings & Blanchard 2004;Trebilco et al 2013;Blanchard et al 2017;Mazurkiewicz et al 2019Mazurkiewicz et al , 2020. A strongly negative relationship between the abundance or biomass of individuals for a given body size range has been consistently documented in aquatic communities, to the point that size-spectra parameters have been recommended as a potential "universal" indicator of ecological health (Petchey & Belgrano 2010).…”

A Influência Das Vertentes Na Gestão Urbana

“…A segunda classificação refere-se ao tamanho da malha do aparato amostral em que o organismo ficou retido, logo chamamos de microbentos os organismos menores que 0,63 mm, meio fauna os organismos entre 0,63 e 0,5 mm e macrofauna os organismos maiores que 0,5-1,0 mm (WILSON; FLEEGER, 2012;KENNISH, 2016). Porém esta última classificação vem sendo cautelosamente revista, dadas às variações nos tamanhos corporais de acordo com a qualidade do alimento e latitude (MAZURKIEWICZ et al, 2020;WARWICK;CLARKE, 1984). Outra questão refere-se à mobilidade dos organismos, eles podem ser sésseis ou fixos e errantes ou móveis.…”