Constancy and change in macrobenthic abundance, biodiversity and assemblage structure along the axis of a flood-tidal sand delta

IF 2.6 3区地球科学 Q1 MARINE & FRESHWATER BIOLOGY

Estuarine Coastal and Shelf Science Pub Date : 2025-04-30 DOI:10.1016/j.ecss.2025.109326

R.S.K. Barnes

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引用次数: 0

Abstract

Flood-tidal deltas commonly occur along microtidal coasts in the mouths of those inlets kept open by tidal currents, but they have seldom been studied ecologically. Such a delta of fine sand occurs in the Knysna estuarine bay, South Africa, extending for some 2 km upstream. Although macrofaunal assemblage metrics (overall abundance, observed and estimated species density, geometric mean morphospecies abundance, evenness, and patchiness) varied little along the deltaic axis, faunal composition changed markedly though without species replacement except in the paraonid polychaetes. Unusually, the sand was dominated by these paraonids (especially Paradoneis lyra capensis) and, over its proximal half, also by the amphipod Urothoe pulchella, but worms steadily increased in importance upstream whilst crustaceans decreased. Noteworthily, a psammodrilid was present - the first record from Africa. The flood-tidal shore fauna contrasted in composition with that of the facing ebb-channel shore (dominated by Dipolydora) and areas upstream of the mouth.

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大型底栖生物丰度、生物多样性和组合结构沿洪水-潮汐沙三角洲轴线的恒定和变化

潮水三角洲通常发生在潮汐流保持开放的入海口的微潮海岸，但很少对其进行生态学研究。这样一个细沙三角洲出现在南非的克尼斯纳河口湾，向上游延伸约2公里。尽管大型动物组合指标（总体丰度、观察和估计的物种密度、几何平均形态物种丰度、均匀度和斑块度）沿三角洲轴变化不大，但除了副多毛类外，动物组成变化明显，但没有物种替代。不同寻常的是，沙中主要是这些副纲动物（尤其是副纲动物），在其近半部分，也有片脚类动物Urothoe pulchella，但蠕虫在上游的重要性稳步上升，而甲壳类动物却在减少。值得注意的是，这里还发现了一只沙母疟原虫——这是非洲的第一个记录。洪水潮汐海岸动物群的组成与面向退潮海峡海岸（以双朵藻为主）和河口上游地区形成对比。

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来源期刊

Estuarine Coastal and Shelf Science 地学-海洋学

CiteScore

5.60

自引率

7.10%

发文量

374

审稿时长

9 months

期刊介绍： Estuarine, Coastal and Shelf Science is an international multidisciplinary journal devoted to the analysis of saline water phenomena ranging from the outer edge of the continental shelf to the upper limits of the tidal zone. The journal provides a unique forum, unifying the multidisciplinary approaches to the study of the oceanography of estuaries, coastal zones, and continental shelf seas. It features original research papers, review papers and short communications treating such disciplines as zoology, botany, geology, sedimentology, physical oceanography.