The density and biomass of mesozooplankton and ichthyoplankton in the Negro and the Amazon Rivers during the rainy season: the ecological importance of the confluence boundary

Author:

Nakajima Ryota1,Rimachi Elvis V.2,Santos-Silva Edinaldo N.2,Calixto Laura S.F.2,Leite Rosseval G.3,Khen Adi1,Yamane Tetsuo4,Mazeroll Anthony I.56,Inuma Jomber C.7,Utumi Erika Y.K.8,Tanaka Akira8

Affiliation:

1. Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA

2. Plankton Laboratory, Biodiversity Coordination, National Institute of Amazonian Research (INPA), Manaus, Amazonas, Brazil

3. National Institute of Amazonian Research (INPA), Manaus, Amazonas, Brazil

4. Biotechnology Laboratory, Amazonas State University (UEA), Manaus, Amazonas, Brazil

5. Soka University of America, Aliso Viejo, CA, USA

6. Amazon Research Center for Ornamental Fishes, Iquitos, Peru

7. Centro de Projetos e Estudos Ambientais do Amazonas (CEPEAM), Manaus, Amazonas, Brazil

8. Instituto Água Floresta e Vida, Manaus, Amazonas, Brazil

Abstract

The boundary zone between two different hydrological regimes is often a biologically enriched environment with distinct planktonic communities. In the center of the Amazon River basin, muddy white water of the Amazon River meets with black water of the Negro River, creating a conspicuous visible boundary spanning over 10 km along the Amazon River. Here, we tested the hypothesis that the confluence boundary between the white and black water rivers concentrates prey and is used as a feeding habitat for consumers by investigating the density, biomass and distribution of mesozooplankton and ichthyoplankton communities across the two rivers during the rainy season. Our results show that mean mesozooplankton density (2,730 inds. m−3) and biomass (4.8 mg m−3) were higher in the black-water river compared to the white-water river (959 inds. m−3; 2.4 mg m−3); however an exceptionally high mesozooplankton density was not observed in the confluence boundary. Nonetheless we found the highest density of ichthyoplankton in the confluence boundary (9.7 inds. m−3), being up to 9-fold higher than in adjacent rivers. The confluence between white and black waters is sandwiched by both environments with low (white water) and high (black water) zooplankton concentrations and by both environments with low (white water) and high (black water) predation pressures for fish larvae, and may function as a boundary layer that offers benefits of both high prey concentrations and low predation risk. This forms a plausible explanation for the high density of ichthyoplankton in the confluence zone of black and white water rivers.

Funder

JSPS Fellowship for Study Abroad

Publisher

PeerJ

Subject

General Agricultural and Biological Sciences,General Biochemistry, Genetics and Molecular Biology,General Medicine,General Neuroscience

同舟云学术

1.学者识别学者识别

2.学术分析学术分析

3.人才评估人才评估

"同舟云学术"是以全球学者为主线,采集、加工和组织学术论文而形成的新型学术文献查询和分析系统,可以对全球学者进行文献检索和人才价值评估。用户可以通过关注某些学科领域的顶尖人物而持续追踪该领域的学科进展和研究前沿。经过近期的数据扩容,当前同舟云学术共收录了国内外主流学术期刊6万余种,收集的期刊论文及会议论文总量共计约1.5亿篇,并以每天添加12000余篇中外论文的速度递增。我们也可以为用户提供个性化、定制化的学者数据。欢迎来电咨询!咨询电话:010-8811{复制后删除}0370

www.globalauthorid.com

TOP

Copyright © 2019-2024 北京同舟云网络信息技术有限公司
京公网安备11010802033243号  京ICP备18003416号-3