Human and conservation factors affect spatial variation of reef fish assemblages in Colombian Pacific reefs

Human populations and conservation efforts are recognized as influential factors that can impact marine communities, but their impacts are variable and occasionally contradictory. Using an empirical database of fish assemblages compiled from 393 underwater visual censuses along the Colombian Pacific Coast, we assessed spatial variation in these assemblages and investigated whether they are influenced by human and conservation factors which have either negative (i.e., number of fishers and market distance) or positive (i.e., conservation status and Marine Protect Area age) effects on fish communities. Our study reveals that remote locations have a higher fish density and biomass than those near the coast. Additionally, we found that grunts (Haemulidae) were the most species-rich family and contributed the most to fish density and biomass. Piscivores were the trophic group most affected by human factors, showing lower species richness, density, and biomass in coastal locations. In contrast, other trophic groups did not show a negative response to human factors across locations. We did not observe an effect of human and conservation factors on the total species richness of fish assemblages, regardless of whether Malpelo was included in the model or not. However, market distance negatively influenced the average fish density and biomass when all locations were included. Our results provide the first quantitative assessment of fish assemblages across the Colombian Pacific Coast, enabling future comparison and enhancing our understanding of the effects of human and conservation activities on the patterns of species richness, density, and biomass of reef fishes in the Eastern Tropical Pacific.人类活动与海洋保护工作被公认为影响海洋群落的重要因子，但其作用效果存在显著变异，且偶尔会呈现矛盾性。 本研究依托哥伦比亚太平洋沿岸393次水下视觉普查（underwater visual censuses）所构建的鱼类群落实测数据库，评估了该区域鱼类群落的空间变异特征，并探究其是否受人类活动与保护因子的调控——这些因子对鱼类群落的作用可分为负面（如渔民数量、距市场的距离）与正面（如保护等级、海洋保护区（Marine Protected Area）设立时长）两类。 研究结果显示，偏远海域的鱼类密度与生物量均高于近岸海域。 此外，本研究发现石鲈科（Haemulidae）是物种丰富度最高的类群，其对区域鱼类总密度与总生物量的贡献也最大。 食鱼性营养类群是受人类活动影响最显著的类群：在近岸海域，该类群的物种丰富度、密度与生物量均处于较低水平。 与之相对，其余营养类群在不同海域中均未表现出对人类活动的负面响应。 无论模型是否纳入马尔佩洛岛（Malpelo）的数据，我们均未发现人类活动与保护因子对鱼类群落总物种丰富度存在显著影响。 但当纳入所有采样点位时，距市场的距离会对鱼类平均密度与平均生物量产生显著的负面效应。 本研究是首次对哥伦比亚太平洋沿岸鱼类群落开展的系统性定量评估，可为后续相关研究提供参照基准，并有助于深化我们对人类活动与保护工作如何影响东热带太平洋（Eastern Tropical Pacific）海域礁栖鱼类的物种丰富度、密度与生物量分布格局的认知。