Condition of rocky reef communities around Tasmania: fish surveys

The data is the quantitative abundance of fish derived from underwater visual census methods involving transect counts at rocky reef sites around Tasmania. This data forms part of a larger dataset that also surveyed megafaunal invertebrate abundance and algal cover for the area. The aggregated dataset allows examination of changes in Tasmanian shallow reef floral and faunal communities over a decadal scale - initial surveys were conducted in 1992-1995, and again at the same sites in 2006-2007. There are plans for ongoing surveys.An additional component was added in the latter study - a boat ramp study looking at the proximity of boat ramps and their effects of fishing. We analysed underwater visual census data on fishes and macroinvertebrates (abalone and rock lobsters) at 133 shallow rocky reef sites around Tasmania that ranged from 0.6 - 131 km from the nearest boat ramp. These sites were not all the same as those used for the comparison of 1994 and 2006 reef communities. The subset of 133 sites examined in this component consisted of only those sites that were characterized by the two major algal (kelp) types (laminarian or fucoid dominated). Sites with atypical algal assemblages were omitted from the 196 sites surveyed in 2006. This study aimed to examine reef community data for changes at the community level, changes in species richness and introduced species populations, and changes that may have resulted from ocean warming and fishing.The methods are described in detail in Edgar and Barrett (1997). Primarily the data are derived from transects at 5 m depth and/or 10 m depth at each site surveyed. The underwater visual census (UVC) methodology used to survey rocky reef communities was designed to maximise detection of (i) changes in population numbers and size-structure (ii) cascading ecosystem effects associated with disturbances such as fishing, (iii) long term change and variability in reef assemblages.

本数据集为塔斯马尼亚周边岩礁海域采用样带计数法开展水下视觉普查（underwater visual census, UVC）所得的鱼类定量丰度数据。该数据隶属于一套更大的综合数据集，后者同步针对该海域开展了大型无脊椎动物丰度与藻类覆盖度调查。整合后的数据集可用于分析塔斯马尼亚浅海岩礁动植物群落在十年尺度上的动态变化：首次调查于1992-1995年间开展，后续于2006-2007年在同一站点进行了复测，目前仍有持续推进调查的计划。

在2006-2007年的后续调查中新增了一项子研究：针对船艇坡道（boat ramp）及其对捕捞活动的影响开展邻近性分析。本次研究针对塔斯马尼亚周边133个浅海岩礁站点的鱼类与大型无脊椎动物（鲍鱼abalone、岩龙虾rock lobsters）的水下视觉普查数据进行了分析，这些站点距最近船艇坡道的距离介于0.6至131千米之间。上述站点并非全部与1994年与2006年岩礁群落对比研究所使用的站点重合。本次子研究所分析的133个站点子集，仅包含以两种以大型褐藻（kelp）为代表的主要藻类类型——海带目（laminarian）或墨角藻目（fucoid）主导——占优的站点。2006年共调查了196个站点，其中藻类群落组成异常的站点被排除在本次研究之外。

本研究旨在基于岩礁群落数据集，分析群落层级的动态变化、物种丰富度与外来物种种群的变动，以及可能由海洋变暖和捕捞活动引发的群落变化。详细的调查方法可参见Edgar与Barrett于1997年发表的研究文献。本数据集主要来源于各调查站点在5米水深与/或10米水深处布设的样带采集数据。本次用于岩礁群落调查的水下视觉普查方法，其设计目标为最大化以下三类观测结果的检出率：(i) 种群数量与体型结构的变化；(ii) 捕捞等扰动引发的生态系统级联效应；(iii) 岩礁群落的长期变化与时空变异。