# The Trophic Cascade Effects of Marine Mesozooplankton: Theory, Dynamics, and Responses to Global Change

## TL;DR

This paper reviews how marine mesozooplankton influence ocean ecosystems and how they respond to global changes like warming and acidification.

## Contribution

The paper introduces a new quantitative framework for studying mesozooplankton-driven trophic cascades and their responses to global change.

## Key findings

- A dual-pathway model distinguishes between density- and trait-mediated trophic cascades.
- A new Cascade Strength Index quantifies the intensity of mesozooplankton-driven cascades.
- Global change drivers like warming and acidification significantly impact mesozooplankton and ecosystem services.

## Abstract

Marine mesozooplankton (0.2–20 mm), as a critical trophic link between primary producers and higher trophic levels, are pivotal drivers of trophic cascades regulating pelagic ecosystem structure and function. This review synthesizes recent advances in understanding mesozooplankton-mediated trophic cascades (MMTC), with a focus on selective feeding mechanisms, and presents an original, integrated quantitative framework that fills gaps in quantification and prediction of MMTC. This framework includes the following: a dual-pathway conceptual model distinguishing density-mediated and trait-mediated cascades; a three-level grazing rate correction model addressing long-standing underestimations of mesozooplankton direct grazing rate on phytoplankton; a comprehensive Cascade Strength Index for quantifying cascade intensity; an extended numerical model—NPMZ model (Nutrient–Phytoplankton–Microzooplankton–Mesozooplankton) for simulating MMTC dynamics and their biogeochemical impacts. The review further elucidates the spatiotemporal heterogeneity of MMTC and its implications for plankton community size structure and biological carbon pump efficiency. It also systematically assess the combined impacts of global change drivers (ocean warming, acidification, eutrophication) on MMTC and their ecological consequences. This review advances the theoretical framework of marine trophic cascade research by establishing a unified quantitative paradigm for MMTC and provides mechanistic insights and predictive tools for understanding how climate change modulates pelagic food web dynamics and marine ecosystem services. Moreover, the proposed integrated research paradigm combining molecular tools, multi-factor experiments, and high-resolution numerical modeling offers a critical roadmap for future MMTC research in the Anthropocene. This provides a scientific basis for the conservation and adaptive management of marine ecosystems under global change.