Ceccherelli Giulia, Addis Piero, Atzori Fabrizio, Cadoni Nicoletta, Casu Marco, Coppa Stefania, De Luca Mario, de Lucia Giuseppe Andrea, Farina Simone, Fois Nicola, Frau Francesca, Gazale Vittorio, Grech Daniele, Guala Ivan, Mariani Mariano, Marras Massimo Sg, Navone Augusto, Pansini Arianna, Panzalis Pieraugusto, Pinna Federico, Ruiu Alberto, Scarpa Fabio, Piazzi Luigi
Dipartimento di Chimica e Farmacia, Universitá di Sassari, Via Piandanna, Sassari, Italy.
Dipartimento di Scienze della Vita e dell'Ambiente, Universitá di Cagliari, Via Fiorelli, Cagliari, Italy.
PeerJ. 2022 Mar 7;10:e12971. doi: 10.7717/peerj.12971. eCollection 2022.
Marine protected areas (MPAs) usually have both positive effects of protection for the fisheries' target species and indirect negative effects for sea urchins. Moreover, often in MPAs sea urchin human harvest is restricted, but allowed. This study is aimed at estimating the effect of human harvest of the sea urchin within MPAs, where fish exploitation is restricted and its density is already controlled by a higher natural predation risk. The prediction we formulated was that the lowest densities of commercial sea urchins would be found where human harvest is allowed and where the harvest is restricted, compared to where the harvest is forbidden.
At this aim, a collaborative database gained across five MPAs in Sardinia (Western Mediterranean, Italy) and areas outside was gathered collecting sea urchin abundance and size data in a total of 106 sites at different degrees of sea urchin exploitation: no, restricted and unrestricted harvest sites (NH, RH and UH, respectively). Furthermore, as estimates made in past monitoring efforts (since 2005) were available for 75 of the sampled sites, for each of the different levels of exploitation, the rate of variation in the total sea urchin density was also estimated.
Results have highlighted that the lowest sea urchin total and commercial density was found in RH sites, likely for the cumulative effects of human harvest and natural predation. The overall rate of change in sea urchin density over time indicates that only NH conditions promoted the increase of sea urchin abundance and that current local management of the MPAs has driven towards an important regression of populations, by allowing the harvest. Overall, results suggest that complex mechanisms, including synergistic effects between natural biotic interactions and human pressures, may occur on sea urchin populations and the assessment of MPA effects on populations would be crucial to guide management decisions on regulating harvest permits. Overall, the need to ban sea urchin harvest in the MPAs to avoid extreme reductions is encouraged, as inside the MPAs sea urchin populations are likely under natural predation pressures for the trophic upgrading.
海洋保护区（MPAs）通常对渔业目标物种具有保护的积极作用，而对海胆具有间接的负面影响。此外，在海洋保护区内，海胆的人类捕捞往往受到限制，但仍被允许。本研究旨在评估在鱼类开发受到限制且其密度已因较高的自然捕食风险而得到控制的海洋保护区内，人类捕捞海胆的影响。我们提出的预测是，与禁止捕捞的区域相比，在允许捕捞和捕捞受限的区域，商业海胆的密度将最低。
为此，收集了撒丁岛（意大利西地中海）五个海洋保护区及周边区域的合作数据库，在总共106个不同海胆开发程度的地点收集海胆丰度和大小数据：无捕捞、捕捞受限和捕捞不受限的地点（分别为NH、RH和UH）。此外，由于75个采样地点有过去监测工作（自2005年以来）的估计数据，对于每个不同的开发水平，还估计了海胆总密度的变化率。
结果表明，RH地点的海胆总密度和商业密度最低，这可能是人类捕捞和自然捕食的累积效应所致。海胆密度随时间的总体变化率表明，只有NH条件促进了海胆丰度的增加，而当前海洋保护区的地方管理通过允许捕捞导致了种群数量的显著减少。总体而言，结果表明，包括自然生物相互作用和人类压力之间的协同效应在内的复杂机制可能会影响海胆种群，评估海洋保护区对种群的影响对于指导捕捞许可证管理决策至关重要。总体而言，鼓励在海洋保护区内禁止捕捞海胆以避免数量极端减少，因为在海洋保护区内，海胆种群可能因营养级提升而面临自然捕食压力。
