What's in a tide pool? Just as much food web network complexity as in large open ecosystems

Abstract

Understanding the fundamental laws that govern complex food web networks over large ecosystems presents high costs and oftentimes unsurmountable logistical challenges. This way, it is crucial to find smaller systems that can be used as proxy food webs. Intertidal rock pool environments harbour particularly high biodiversity over small areas. This study aimed to analyse their food web networks to investigate their potential as proxies of larger ecosystems for food web networks research. Highly resolved food webs were compiled for 116 intertidal rock pools from cold, temperate, subtropical and tropical regions, to ensure a wide representation of environmental variability. The network properties of these food webs were compared to that of estuaries, lakes and rivers, as well as marine and terrestrial ecosystems (46 previously published complex food webs). The intertidal rock pool food webs analysed presented properties that were in the same range as the previously published food webs. The niche model predictive success was remarkably high (73–88%) and similar to that previously found for much larger marine and terrestrial food webs. By using a large-scale sampling effort covering 116 intertidal rock pools in several biogeographic regions, this study showed, for the first time, that intertidal rock pools encompass food webs that share fundamental organizational characteristics with food webs from markedly different, larger, open and abiotically stable ecosystems. As small, self-contained habitats, intertidal rock pools are particularly tractable systems and therefore a large number of food webs can be examined with relatively low sampling effort. This study shows, for the first time that they can be useful models for the understanding of universal processes that regulate the complex network organization of food webs, which are harder or impossible to investigate in larger, open ecosystems, due to high costs and logistical difficulties.

Consistent predator-prey biomass scaling in complex food webs

“…Further research would be instructive to understand if these are general patterns across different types of terrestrial and aquatic ecosystems. For instance, whilst rock pool webs display very similar network topology and PPmR scaling as open marine webs 25,26 , we might expect different scaling patterns in pelagic marine webs where trophic interactions take place in three dimensions 21 , where ontogenetic diet shifts are common 27 , and where food chains are long 13 . Adapting our food-web approach to quantify biomass scaling among size classes would likely be informative for tackling these additional complexities.…”

“…We collated available food web datasets from a global database of traits and food-web architecture (GATEWAy v.1.0; 26 ), where biomass and trophic interaction data were available across a large biomass gradient. Datasets for three ecosystem types met these requirements: UK freshwater streams 30,31 , a global compilation from marine intertidal rock pools 25,33 and terrestrial soils of European forests 34,35 (Table S1).…”

Long-term monitoring dataset of fish assemblages in rocky tidepools on the southern coast of Taiwan

“…Fish assemblages in the intertidal zone on the reef coasts of the Pacific Ocean 2 , 5 , 6 , the USA 7 , 8 , Japanese islands 9 , 10 , and Western Europe 11 – 13 have been studied. Many of these reports have investigated seasonal and annual changes in community structures 5 , 8 , 14 , 15 and food web network 16 , and in the context of the resilience and stability of assemblages 5 , 17 . However, relatively few studies have been long-term surveys 7 , 8 , 18 , and there are few reports from tropical and subtropical areas 19 .…”

Patterns of rockpool molluscs in differing shore exposures

“…rockpools, representing mesocosms of marine life (Legrand et al 2018). Compared to the surroundings, the environment inside these rock pools is substantially less harsh due to the lower amplitude of physicochemical uctuations (temperature, salinity, pH, and dissolved O2), offering refuge, feeding areas, and nurseries for several marine species ( Mendonça et al 2018). The study of rockpools is of extreme importance due to their proven vulnerability to climate change, namely global warming, sea level rise, and overall anthropogenic activities that can lead to an abrupt biodiversity loss in these coastal areas (Fairchild et al 2018; González-Murcia et al 2020).…”

“…Whereas intertidal rocky shore platforms have been well studied, intertidal rock pools therein have received relatively less attention, particularly on their community dynamics (Martins et al 2007; Mendonça et al 2018). However, there has been growing interest in determining the biotic (e.g.…”