The structure of demersal fish assemblages in a cold, highly stratified environment

Abstract Chouinard, P-M., and Dutil, J-D. 2011. The structure of demersal fish assemblages in a cold, highly stratified environment. – ICES Journal of Marine Science, 68: 1896–1908. Fish are a major component of marine ecosystems, with many species co-occuring in the same habitats. Potential interactions among species and with the environment can be studied through the identification of species assemblages. Data from bottom trawl surveys (2004–2008) conducted in the estuary and northern Gulf of St Lawrence were analysed using multivariate methods (cluster, multidimensional scaling, and detrended canonical correspondence analysis) to describe the structure and composition of demersal fish assemblages, including rare and smaller non-commercial species. The spatial variability in environmental conditions that characterizes the study area has a significant impact on the composition of fish assemblages in the region. In all, 35 taxa were classified as key, and 6 main fish assemblages were described, based on catch in numbers. These assemblages had a coherent spatial distribution in the study area, associated with either depth, salinity and temperature, or dissolved oxygen. The analyses showed overall strong correlations between species abundance and prevalent environmental conditions and explained 18.4% of the variance in species abundance data and 79.2% of the variance in the species–environment relationship.

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Demersal Fish Assemblages in NE Atlantic Seagrass and Kelp

Diversity ◽

10.3390/d12100366 ◽

2020 ◽

Vol 12 (10) ◽

pp. 366

Author(s):

Evie Furness ◽

Richard K.F. Unsworth

Keyword(s):

Species Richness ◽

Fish Assemblages ◽

Demersal Fish ◽

Kelp Forests ◽

Evidence Based ◽

Ecological Value ◽

Commercial Fish ◽

Seagrass Meadows ◽

The North ◽

Commercial Species

Global fisheries are in decline, calling for urgent evidence-based action. One such action is the identification and protection of fishery-associated habitats such as seagrass meadows and kelp forests, both of which have suffered long-term loss and degradation in the North Atlantic region. Direct comparisons of the value of seagrass and kelp in supporting demersal fish assemblages are largely absent from the literature. Here, we address this knowledge gap. Demersal fish were sampled using a baited camera to test for differences between habitats in (1) the species composition of the fish assemblages, (2) the total abundance and species richness of fishes, and (3) the abundances of major commercial species. Seagrass and kelp-associated fish assemblages formed two significantly distinct groupings, which were driven by increased whiting (Merlangius merlangus) and dogfish (Scyliorhinus canicula) presence in seagrass and higher abundances of pollock (Pollachius pollachius) and goby (Gobiusculus flavescens) in kelp. The abundance, diversity, and species richness did not change significantly between the two habitats. We conclude that seagrass and kelp do support unique demersal fish assemblages, providing evidence that they have different ecological value through their differing support of commercial fish species. Thus, this study improves the foundation for evidence-based policy changes.

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Changes in the exploited demersal fish assemblages in the Southern Grand Banks (NAFO Divisions 3NO): 2002–2013

ICES Journal of Marine Science ◽

10.1093/icesjms/fsu182 ◽

2014 ◽

Vol 72 (3) ◽

pp. 753-770 ◽

Cited By ~ 4

Author(s):

Adriana Nogueira ◽

Xabier Paz ◽

Diana González-Troncoso

Keyword(s):

Fish Assemblages ◽

Demersal Fish ◽

Fishing Effort ◽

Size Spectra ◽

Grand Banks ◽

Environmental Regimes ◽

Commercial Species ◽

Faunal Diversity ◽

Different Levels ◽

Population Rate

Abstract The Newfoundland Shelf supported one of the world’s greatest fisheries until the main commercial species collapsed more than two decades ago. We calculated three ecological indices for individual populations and five for community from the data obtained in the research surveys conducted by Spain in NAFO Regulatory Area Divisions 3NO between 2002 and 2013. We use data for 24 species to study the dynamics of major demersal fish assemblages (38–300, 301–600, and 601–1460 m depth) and evaluated how they have responded to different levels of exploitation. Trends and changes for individual populations (abundance and biomass, intrinsic population rate of growth, and mean length) and for all the community (ABC curves, indices of faunal diversity, proportion of non-commercial species, mean length in community and size spectra) were used to test ecological trends. Indices showed no homogeneous status and responded to different exploitation patterns, management, and environmental regimes in each assemblage. Our results show an improvement in the shallower and deeper assemblages and that fishing effort does not explain differences among each assemblage.

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Assessing the impact of fisheries on demersal fish assemblages of the Mauritanian continental shelf, 1987–1999, using dominance curves

ICES Journal of Marine Science ◽

10.1016/j.icesjms.2004.11.007 ◽

2005 ◽

Vol 62 (3) ◽

pp. 380-383 ◽

Cited By ~ 14

Author(s):

Didier Jouffre ◽

Cheikh A. Inejih

Keyword(s):

Species Composition ◽

Continental Shelf ◽

Fish Assemblages ◽

Demersal Fish ◽

Octopus Vulgaris ◽

Taxonomic Information ◽

Associated Species ◽

The Impact ◽

Trawl Surveys

Abstract The assemblages of demersal fish and associated species of the Mauritanian continental shelf are characterized on the basis of annual trawl surveys conducted during the period 1987–1999. Species composition is dominated by exploited species (Dentex spp., Pagellus bellottii, and Octopus vulgaris). Dominance curves (Abundance Biomass Comparison plots) were used to evaluate the impact of fisheries, which have increased in magnitude over several decades. The diagnosis of a “stressed” assemblage seems to converge with the results of a similar study conducted off Senegal, but here there was no trend in impact during the period of study. The sensitivity of the present results to the various ways of considering the available taxonomic information is also analysed.

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Analysis of demersal fish assemblages of the Tuscany and Latium coasts (north-western Mediterranean)

Scientia Marina ◽

10.3989/scimar.2002.66s2233 ◽

2002 ◽

Vol 66 (S2) ◽

pp. 233 ◽

Cited By ~ 29

Author(s):

Franco Biagi ◽

Paolo Sartor ◽

Gian Domenico Ardizzone ◽

Paola Belcari ◽

Andrea Belluscio ◽

...

Keyword(s):

Species Composition ◽

Continental Shelf ◽

Fish Assemblages ◽

Demersal Fish ◽

Western Mediterranean ◽

Similar Species ◽

The European Union ◽

The North ◽

North Western ◽

Trawl Surveys

A four-year time series (1994-1997) of groundfish trawl surveys performed within the European Union Project MEDITS (Mediterranean International Trawl Surveys), was analysed to identify and describe the fish assemblages along the continental shelf and slope of Tuscany and Latium (Italy), in the north-western Mediterranean. Cluster analysis was used to group samples with similar species composition in terms of abundance, biomass and frequency of occurrence. Results allowed the identification of four to five broad assemblages along the depth gradient: a strictly coastal group (< 50 m depth), two groups in the upper and lower part of the continental shelf (essentially 50-200 m), an epibathyal group (200-450 m) and a group derived from hauls made at depths greater than 450 m. Each assemblage corresponded to a faunistic association with relatively homogeneous and persistent species composition, biomass and density indices.

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Comparison of fish assemblages between the Sea of Marmara and the Aegean Sea (north-eastern Mediterranean)

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315410002213 ◽

2011 ◽

Vol 91 (6) ◽

pp. 1307-1318 ◽

Cited By ~ 5

Author(s):

Cetin Keskin ◽

Francesc Ordines ◽

Beatriz Guijarro ◽

Enric Massutí

Keyword(s):

Environmental Conditions ◽

Fish Assemblages ◽

Eastern Mediterranean ◽

Aegean Sea ◽

Demersal Fish ◽

Sea Of Marmara ◽

The North ◽

Eastern Aegean ◽

North Eastern ◽

Eastern Aegean Sea

The demersal fish assemblages of the south-western Sea of Marmara and the north-eastern Aegean Sea were examined in relation to their biogeographical and environmental conditions. Sampling was carried out during bottom trawl surveys conducted during five periods between June 2006 and August 2007. A total of 40 hauls were processed, including 16 in the Sea of Marmara (38–74 m deep) and 24 in the north-eastern Aegean Sea (63–401 m deep). A total of 47,940 individuals, from 91 species and 47 families were collected. Cluster analysis of catch data indicated that there were three assemblages, one in the shelf of the Sea of Marmara and two in the Aegean Sea (<100 and >200 m depth). The numerical abundance and biomass of fish, mean fish weight, mean species richness, diversity and evenness were compared between these assemblages. Multivariate analysis was used to test differences in environmental conditions between areas, and relationships between species and environmental variables were explored by using redundancy analysis. In addition to bathymetric differences, differences in both diversity and species composition were observed between shelf assemblages in the two nearby areas. The distinct biogeographical, environmental characteristics (depth, dissolved oxygen and temperature) and fishing pressure are discussed as the main factors which could explain the differences detected.

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Demersal fish assemblages off São Sebastião, southeastern Brazil: structure and environmental conditioning factors (summer 1994)

Revista Brasileira de Oceanografia ◽

10.1590/s1413-77392000000100002 ◽

2000 ◽

Vol 48 (1) ◽

pp. 09-27 ◽

Cited By ~ 14

Author(s):

Elizabeti Y. Muto ◽

Lucy S. H. Soares ◽

Carmen L. D. B. Rossi-Wongtschowski

Keyword(s):

Fish Assemblages ◽

Species Abundance ◽

Demersal Fish ◽

Outer Shelf ◽

Southeastern Brazil ◽

Otter Trawl ◽

Brazilian Coast ◽

Inner Shelf ◽

Bottom Water Temperature ◽

Environmental Conditioning

The demersal fish community of the Channel and shelf of São Sebastião (SP), on the southeastern Brazilian coast, was investigated during the summer of 1994. The sampling was carried out usinga bottom otter trawl at 26 stations located between 8 m and 65 m in depth. Ninety-three species of 40 families were identified in the area. Sciaenids were the most prominent in number of species, abundance, and weight. Ctenosciaena gracilicirrhus, Paralonchurus, brasiliensis, and Cynoscion jamaicensis dominated in the catches. Cluster analysis showed three major groups of species and three groups of sites. The first group was composed of species found in the Channel and shallower areas of the inner shelf, the second of species associated with the inner shelf «50 m depth), and the third group of species fTom the outer shelf (> 50 m depth). Environrnental variables considered in Canonical Correspondence Analysis (CCA) explained 51 % of the variation in the species data. Bottom water temperature was the most important variable selected by CCA, accounting for 21% of the explainable variance. The results revealed that structure of the ichthyofauna was associated with water mass distribution. During the period studied, the area was occupied by the warm Coastal Water (CW), but cold South Atlantic Central Water (SACW) was detected over the bottom or the outer shelf, influencing the distribution and abundance ofthe main species.

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Dissolved oxygen and temperature best predict deep-sea fish community structure in the Gulf of California with climate change implications

Marine Ecology Progress Series ◽

10.3354/meps13240 ◽

2020 ◽

Vol 637 ◽

pp. 159-180

Author(s):

ND Gallo ◽

M Beckwith ◽

CL Wei ◽

LA Levin ◽

L Kuhnz ◽

...

Keyword(s):

Climate Change ◽

Community Structure ◽

Community Composition ◽

Environmental Conditions ◽

Deep Sea ◽

Gulf Of California ◽

Fish Community ◽

Demersal Fish ◽

Fish Community Structure ◽

Explained Variance

Natural gradient systems can be used to examine the vulnerability of deep-sea communities to climate change. The Gulf of California presents an ideal system for examining relationships between faunal patterns and environmental conditions of deep-sea communities because deep-sea conditions change from warm and oxygen-rich in the north to cold and severely hypoxic in the south. The Monterey Bay Aquarium Research Institute (MBARI) remotely operated vehicle (ROV) ‘Doc Ricketts’ was used to conduct seafloor video transects at depths of ~200-1400 m in the northern, central, and southern Gulf. The community composition, density, and diversity of demersal fish assemblages were compared to environmental conditions. We tested the hypothesis that climate-relevant variables (temperature, oxygen, and primary production) have more explanatory power than static variables (latitude, depth, and benthic substrate) in explaining variation in fish community structure. Temperature best explained variance in density, while oxygen best explained variance in diversity and community composition. Both density and diversity declined with decreasing oxygen, but diversity declined at a higher oxygen threshold (~7 µmol kg-1). Remarkably, high-density fish communities were observed living under suboxic conditions (<5 µmol kg-1). Using an Earth systems global climate model forced under an RCP8.5 scenario, we found that by 2081-2100, the entire Gulf of California seafloor is expected to experience a mean temperature increase of 1.08 ± 1.07°C and modest deoxygenation. The projected changes in temperature and oxygen are expected to be accompanied by reduced diversity and related changes in deep-sea demersal fish communities.

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