Temporal Variation in the Ecological Functioning of Benthic Communities After 20 Years in the Eastern Mediterranean

Irini Tsikopoulou,Panagiotis D Dimitriou,Nikolaos Lampadariou,Christopher J Smith,Nadia Papadopoulou,Ioannis Karakassis

doi:10.3389/fmars.2021.768051

Irini Tsikopoulou, Panagiotis D Dimitriou + Show 4 more

Open Access

https://doi.org/10.3389/fmars.2021.768051

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Abstract

Marine benthic ecosystems face well-documented changes as a result of human activities. Describing these changes is important for predicting ecosystem functioning. In this context, long-term changes in soft-bottom macrofaunal communities after a quarter of a century were studied in the south Aegean Sea with the purpose of investigating whether temporal changes in taxa diversity are accompanied by changes in functional diversity, and secondly to determine the main mechanisms driving these changes (i.e., deterministic versus stochastic processes). To achieve this, a large data set that included species abundance data collected in 1990 and 2014 from several sampling sites along a transect line was used. A biological trait analysis (BTA) was conducted to determine the species functional roles. The results revealed a decline in taxonomic alpha and beta diversity metrics between 1990 and 2014, a difference that was also reflected in functional richness, partially in functional redundancy, but not in functional composition. The stability of functional composition indicated that replacements of functionally similar taxa may occur, ensuring the resilience of the ecosystem to provide goods and services. Finally, the comparison of co-occurrence and functional networks for 1990 indicated a non-differentiation with the null model and, it was not possible to determine if the benthic community was structured due to stochastic processes (e.g., dispersal, natural phenomena) or an overlap of deterministic processes (e.g., niche-filtering, competition). In contrast, the comparison of networks for 2014 pointed out that environmental conditions have acted as a major filter on species distribution.

Highlights

Human activities are driving rapid changes in the marine environment
Biodiversity change over time has two facets: temporal alpha diversity, which is an expression of change in the abundance and structure of assemblages, and temporal beta diversity which tracks changes attributed to species composition (Legendre, 2019; Magurran et al, 2019)
Changes in the univariate biodiversity and functional diversity indices among the factors, year and depth, and their statistical significance are shown in Figure 2 and Table 3, respectively

Summary

Introduction

Human activities are driving rapid changes in the marine environment. In the current times of global change, marine ecosystems are affected by many anthropogenic activities, and face unique threats such as ocean acidification and climate change (Halpern et al, 2008). Temporal Variation in Ecosystem Functioning in measuring beta diversity is to capture the ongoing temporal changes in a way that reflects the ecological processes, and the ecosystem functions, that are involved (Magurran et al, 2019). In this context, an increasing interest in the predictability in the function of marine ecosystems has been raised (Worm et al, 2006; Gogina et al, 2017). The identity of organisms in terms of their activity and function are known to influence both the magnitude, and the variability of ecosystem processes (Solan et al, 2008)

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