Benthic meiofauna with emphasis on nematode assemblage response to environmental variation in the intertidal zone of the Danshuei River estuary, northwest Taiwan

A functional perspective of nematode assemblages as proxy of quality in tropical estuarine tidal flats

Functional aspects of biological communities influence ecosystem processes and it is urgent to understand how human disturbances affect functional diversity and ecosystem functions and services. Our purpose was to address the use of different functional metrics of nematode assemblages to evaluate the ecological status of tropical estuaries subjected to different human activities, aiming to advance and improve the knowledge about the usefulness of functional attributes as indicators of environmental quality. Three approaches were compared: functional diversity indexes, single trait, and multi traits using the Biological Traits Analysis. The RLQ + fourth-corner combined method was used to identify relationships among functional traits, inorganic nutrients, and metals concentrations. Lower values of FDiv, FSpe, and FOri indicate a convergence of functions, characterizing impacted conditions. A dominant set of traits was related to disturbance, mainly inorganic nutrient enrichment. All the approaches allowed for the detection of disturbed conditions, however, multi traits was the most sensitive one.

Free-living marine nematodes community structure in the conservation area (Chaojing Park) and its adjacent area of Keelung, Taiwan

Studies conducted in the same seas or even study sites nearby each other, showed very different community structure, implying the patchiness of free-living marine nematodes which may be related to the sedimentary environment such as sediment type and food availability of the study area. This study was motivated by the concerns about the impacts of high level of anthropogenic activities on Chaojing Park (gazetted as Wanghaixiang’s Chao-Jing Bay Resource Conservation Area (WCJBRA) in 2016). The present study provides baseline knowledge of free-living marine nematode community structure in WCJBRA and identify potential marine nematodes as bioindicators to indicate possible impacts of the anthropogenic activities to the Chaojing Park. A total of 15 stations were selected in the subtidal zones of WCJBRA and its adjacent area. Marine nematode sample collection was carried out on the 13th and 14th of September 2019 using SCUBA diving technique. Results showed positive correlation between nematode density and medium sand (500μm-1.0mm). Presence of certain species such as Daptonema sp., Pomponema sp. and Innocuonema sp. indicates presence of disturbances in S12 and S13. Several species also showed potential to be introduced as indicator for healthy environment subjected to further studies on nematode-pollutants relationship, particularly on autecology as per se. Higher species diversity, H’ index of S1-S8 and S11 was categorised as Good Condition; followed by station with moderate species diversity index (S9, S10, S14 –Moderate Condition) zone; and lastly S12, S13 and S15 (Poor Condition).

Comparison of benthic nematode assemblages in native mangrove forest and exotic mangrove plantations (Sonneratia apetala Buch-Ham) along the South China Coast

The exotic mangrove species Sonneratia apetala has been planted widely in China since 1985. As an exotic mangrove species, it is important to understand the influence of Sonneratia plantations on marine nematode assemblages. We studied the Zhanjiang and Xiatanwei mangrove wetlands on the South China Coast during the four seasons of 2010 and 2019. The results showed that S. apetala plantations increased the number of genera, Shannon-Wiener diversity, richness, evenness, maturity index (MI) and decreased the index of trophic diversity (ITD) values for nematodes compared to those in mudflats, but did not change significantly compared to those of native mangrove forests. In addition, Sonneratia plantations did not significantly change nematode assemblages compared to those of native mangroves, though they did change significantly compared to those in mudflats. Thus, interplanting S. apetala into native mangrove forests may be an effective substitute for using native mangroves in mangrove plantation.