WAMSI 2 - Dredging Node - Project 6.3 Defining Thresholds and Indicators of Filter-feeder Response to Dredging Related Pressures - FIELD SURVEYS, Western Australia

Project 6.3 - Field surveys: The objective of this work is to provide in situ community level data (major taxa and species, diversity, dominant growth forms, abundance, density etc.) for local filter feeders at two scales of survey (large scale: underwater video and scoring, small scale: SCUBA, sampling and analyses) and reveal which taxa or growth forms are habitat-forming and should be used for the experimental work (Project 6.4). The main focus will be on sponges, but other filter feeders will also be included at Class level (sponges vs. tunicates vs. cnidarians vs. bryozoans). In addition, this work will identify changes before vs. after the dredging work and therefore validate parts of the tank work. Subject to the consistency of responses across all filter feeders or immediately obvious patterns, we aim to identify of the most vulnerable organisms that may be used as biomonitors, and responses that may act as bioindicators for dredging-related stress. Samples will be collected to determine community attributes such as proportion of heterotrophy vs. phototrophy etc. Fieldwork was conducted during two trips (2013 and 2015) aligned with dredging activities at Chevron's Wheatstone Project to allow a 'before dredging' assessment in comparison to 'after'.. Field surveys were conducted at two scales using different methods and answering different questions. Large-scale surveys: Sampling was conducted using underwater towed video. Some general principles are that (1) sample before any dredging activities have started and afterwards, (2) subject to access and benthic communities found by video work we will sample in nearshore, mid and offshore zones, and (3) where possible sample areas where there are existing baseline data or areas that will be monitored throughout the program in the compliance with the monitoring program (monitoring is thought to be based on quarterly sampling), (4) emphasize sampling in the ZHI where dredging impacts are likely and where sampling is often not conducted during dredging programs (as these areas are effectively sacrificial). Small-scale surveys: Replicated IS x 1m belt transects will be investigated and sampled on SCUBA depending on preliminary findings from the video work and conducted according to WAM protocol.

项目6.3——野外调查：本工作旨在针对本地滤食性生物，从两种调查尺度（大规模：水下视频与评分；小规模：水肺潜水（SCUBA）、采样与分析）提供原位群落水平数据（主要类群与物种、多样性、优势生长型、丰度、密度等），并揭示哪些类群或生长型具有栖息地形成功能，可用于后续实验工作（项目6.4）。研究重点将放在海绵上，但也会纳入纲级别的其他滤食性生物（海绵vs被囊动物vs刺胞动物vs苔藓动物）。此外，本工作将识别疏浚前后的变化，从而验证水槽实验工作的部分内容。根据所有滤食性生物响应的一致性或直接明显的模式，我们旨在识别可作为生物监测指标的最脆弱生物，以及可作为疏浚相关胁迫生物指示剂的响应。将采集样本以测定群落特征，如异养与自养比例等。野外工作于2013年和2015年分两次考察进行，与雪佛龙惠斯通项目的疏浚活动同步，以便开展疏浚前后的对比评估。

大规模调查：采用拖曳式水下视频进行采样。一般原则包括：（1）在疏浚活动开始前及结束后进行采样；（2）根据可达性及视频工作发现的底栖群落，在近岸、中岸及远岸区域开展采样；（3）尽可能在已有基线数据或需全程按监测方案（监测拟基于季度采样）进行监测的区域采样；（4）重点在ZHI区域采样——该区域易受疏浚影响，且疏浚期间通常不进行采样（因这些区域实际上是牺牲性区域）。

小规模调查：根据视频工作的初步结果，通过水肺潜水对重复的1×1米带状样方进行调查与采样，并遵循WAM协议开展。