The effect of landscape composition and configuration on the spatial distribution of temperate demersal fish

Abstract

In contrast to the terrestrial environment, where the use of landscape analyses has been clearly demonstrated, the influence of landscape composition and configuration on the abundance and spatial distribution of marine organisms remains poorly understood. Development of this area of marine research has been limited by the lack of accurate benthic habitat maps, particularly for marine environments deeper than can be penetrated by optical remote sensing (<10 m). However, the recent availability of detailed (1:25 000) and accurate habitat maps derived from hydroacoustic surveys of deeper marine waters has redressed this situation. The aim of this research was to establish the strength and significance of derived landscape composition and configuration indices on the demersal fish assemblage structure and spatial distribution. A combination of depth and 6 landscape measures were found to explain 34.8% of the variation in the fish assemblage. Depth contributed the highest percentage of the variance explained, accounting for 23.7%. Distance to reef was the most important landscape index explaining 7.1% of the variability, followed by total length of edge environment (the interface between different benthic substrates) explaining 1.5%. Species responsible for driving the structure of the fish assemblage were also examined and found to respond not only to the proximity of reef but also to the configuration of the reef. For example, Parika scaber and Pseudolabrus psittaculus characterised more heterogeneous landscapes offering clusters of small interconnected patches of reef with a lot of edge environment, whilst juvenile Trachyurus novaezelandiae and Platycephalus caeruleopunctatus preferred more homogeneous landscapes offering little reef or edge environment. This research demonstrated that a broad scale landscape analysis, employing indices of landscape composition and configuration, is important for understanding demersal fish assemblage structure and spatial distribution.

On a landscape ecology of a harlequin environment: the marine landscape

“…The paradigm of landscape ecology has made some inroads into the study of coastal systems (Bell et al 2008;Hinchey et al 2008;Pittman et al 2011), but is poorly known for marine organisms and processes in pelagic systems (Moore et al 2010). This is true despite that spatial and temporal discontinuities in energy and matter, which are characteristic of this fluid medium, are major drivers of biotic patterning (Legendre and Demers 1984).…”

“…For example, Moore et al (2010) found that depth and six landscape metrics helped predict demersal fish assemblage structure and spatial distribution. Ciannelli and Bailey (2005) used a landscape ecology approach to understand the link between landscape dynamics, climate forcing, and ecological interactions between cod and capelin in the Bering Sea.…”

“…This includes physical features such as seamounts and certain bathymetric features, as well as geographically fixed biological units such as mangroves or salt marshes, or relatively sedentary species such as orange roughy (Hoplostethus atlanticus), flounder (Platichthys flesus L.), and coral reef fishes (Ciannelli and Bailey 2005). Technological advances in remote sensing and GPS are aiding in quantifying seascape structure (Moore et al 2010).…”

“…In essence, while humanscaled studies may reveal emergent properties and general patterns, these properties and patterns happen to manifest themselves at a scale coincident with the human scale. Further, Moore et al (2010), among others, pointed out our perception of ocean is constrained by our ability to measure it, which is much different from terrestrial systems that we can visually see and, therefore, have an intuitive sense of the accuracy of our measurements. Stenseth et al (2005) commented on differences between marine and terrestrial ecology and the role of perception thusly: ''The world is also perceived differently from a ship struggling through the white waves of the Northern Atlantic than from under a spruce tree in the deep forest.''…”

Bait increases the precision in count data from remote underwater video for most subtidal reef fish in the warm-temperate Agulhas bioregion

“…Over the last decade, the BRUV method has gained considerable support with research investigating the effects of fishing and protection on ecosystems and species (Babcock et al 1999, Willis et al 2003, Cappo et al 2007a, Malcolm et al 2007, Watson et al 2007, Goetze et al 2011, McLean et al 2011) and the effect of environmental conditions on fish distribution patterns (Brooks et al 2011, Moore et al 2011, Birt et al 2012, Cheung et al 2012. At the same time, the BRUV method has undergone further development , Watson et al 2005, 2010, Stobart et al 2007, Merritt et al 2011) and rigorous testing against traditional fish monitoring me thods, such as angling, underwater visual census (UCV), traps and trawls , Cappo et al 2004, Watson et al 2005, Colton & Swearer 2010, Pelletier et al 2011.…”