Heterogeneity of ecological patterns, processes, and funding of marine manipulative field experiments conducted in Southeastern Pacific coastal ecosystems

Abstract

Ecological manipulative experiments conducted in marine coastal ecosystems have substantially improved ecological theory during the last decades and have provided useful knowledge for the management and conservation of coastal ecosystems. Although different studies report global trends in ecological patterns worldwide, Southeastern Pacific coastal ecosystems have been poorly considered. Given that the SE Pacific coast encompasses diverse coastal ecosystems, consideration of studies conducted along this range can shed light on the heterogeneity of processes regulating coastal communities. We reviewed the biotic interactions and habitat type considered, as well as the complexity in terms of spatial and temporal extent of manipulative field experimental studies conducted along the SE Pacific coast from 0°S to 56°S (Ecuador to Chile). We test the effect of funding reported by different studies as a main factor limiting experimental complexity. From field ecological studies published from 1970 to 2016, we found that 81 studies were truly manipulative, in which one or multiple factors were “manipulated.” Around 77% of these studies were located between 21°S and 40°S, and conducted in intertidal rocky habitats. An increase in experimental studies was observed between 2010 and 2015, especially focused on herbivore–alga interactions, although we found that both the temporal extent and spatial extent of these studies have shown a decrease in recent decades. Funding grant amount reported had a positive effect on elapsed time of field experiments, but no effect was observed on spatial extent or in the biotic interactions considered. Elapsed time of experiments was different among the main biotic interactions considered, that is, herbivory, predation, and competition. We suggest that to further progress in applied ecological knowledge, it will be necessary to consider pollution and urbanization processes explicitly using a field experimental framework. This information could improve our understanding of how ecosystems present along the SE Pacific coast respond to climate change and increased levels of human interventions.

A tale of two key species in a subtropical mudflat: four-fold density increases produce minimal ecological response in macrofauna

“…Coastal ecosystems are under intense pressure from anthropogenic activities (Williams et al 1990;MEA 2005;IPCC 2014;McPhee 2017;Newton et al 2020), and an improved understanding of their dynamics is required to anticipate how marine ecosystems, and the services they deliver, might change in the future. In situ experimental density manipulations of organism densities have shown how communities and the associated ecosystem functions respond to change (Wilson 1991;Bertness et al 2014;Ling et al 2015;Aguilera et al 2018;Booty et al 2020). Therefore, we hypothesised that the macrofaunal assemblage structure, their collective biological traits (and, by extension, mudflat functioning), and the abiotic environment would respond to increased densities of the crab Macrophthalmus setosus and the mud whelk Pyrazus ebeninus.…”