Landscape context and nutrients modify the effects of coastal urbanisation

Yabsley, Nicholas A.; Gilby, Ben L.; Schlacher, Thomas A.; Henderson, Christopher; Connolly, Rod M.; Maxwell, Paul; Olds, Andrew D.

doi:10.1016/j.marenvres.2020.104936

Cited by 11 publications

(4 citation statements)

References 185 publications

(103 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Here, we manipulated the condition of a common fisheries species, yellowfin bream ( Acanthopagrus australis , Günther, 1859), via reductions in feed as a proxy for poor habitat quality, and measured a suite of morphometric and biochemical indices through time to interrogate correlations amongst indices. The species is found in coastal habitats such as seagrass (Gaines et al., 2020) and saltmarsh (Jones et al., 2021), and around coastal urban infrastructure (Yabsley et al., 2020). Despite having a generalized diet of benthic invertebrates (Hadwen et al., 2007), its reliance on food webs based on vegetated coastal habitats such as seagrass, saltmarsh and mangroves (Melville & Connolly, 2003) indicates a vulnerability to coastal habitat loss.…”

Section: Introductionmentioning

confidence: 99%

The utility of non‐lethal morphometrics to evaluate fish condition

Newbery,

Connolly,

Melvin

et al. 2024

Austral Ecology

Self Cite

View full text Add to dashboard Cite

The condition of fish relates to their energy reserves, and a suite of proxies exist to approximate condition, including biochemical and morphometric indices. Biochemical indices directly measure energy stores but are expensive and sometimes lethal. Morphometrics offer several advantages, but their utility as condition proxies is debated and largely untested experimentally. Here, we manipulated the condition of yellowfin bream (Acanthopagrus australis, Günther, 1859) via food reduction to simulate the effect of poor habitat quality and calculated a variety of condition indices through time. We measured four non‐lethal morphometrics (Fulton's K, Le Cren's relative condition, width‐to‐length ratio and girth), the hepatosomatic index and a biochemical benchmark (liver lipid content). Girth and width‐to‐length ratio were reasonably well correlated with lipid content (R2 = 0.74 and 0.56, respectively). The hepatosomatic index was only weakly or uncorrelated to other indices, including lipid content (R2 = 0.35). Where precise estimates of body condition are not needed or repeat measures on the same individual are useful, non‐lethal morphometrics provide a fast, cheap and non‐lethal alternative to biochemical and lethal morphometric methods for this species. We finish by outlining how artificial intelligence‐based automation can be combined with morphometrics to further enhance ethical monitoring by eliminating the need to capture and handle fish entirely.

show abstract

Section: Introductionmentioning

confidence: 99%

The utility of non‐lethal morphometrics to evaluate fish condition

Newbery,

Connolly,

Melvin

et al. 2024

Austral Ecology

Self Cite

View full text Add to dashboard Cite

show abstract

“…Surf zone assemblages may also be exposed to multiple stressors linked to human activities, such as urbanization, tourism and fishing (Costa et al, 2017a). However, the identification of these combined effects on surf zone fishes have gone largely unexplored with focus instead on fish communities in other adjacent aquatic environments such as rivers (Tejerina‐Garro et al, 2005), estuaries (Yabsley et al, 2020) and reefs (Taira et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Revealing the drivers of taxonomic and functional diversity of nearshore fish assemblages: Implications for conservation priorities

Esmaeili

Corte

Checon

et al. 2021

Diversity and Distributions

View full text Add to dashboard Cite

Aim: Understanding patterns and drivers of biodiversity are essential towards developing effective conservation strategies for shallow marine habitats broadly. However, little is known about the natural and anthropogenic factors that structure fish biodiversity of sandy beaches, one of the largest and most socio-economically valuable nearshore habitats due to their endemic fauna, economic importance and cultural relevance. Here, we investigated how environmental variables and urbanization affect taxonomic and functional diversity of nearshore fish assemblages to provide general biodiversity patterns that can serve as baseline information for management plans when considering conservation prioritization.Location: Southeast Brazil. Methods:We surveyed fish communities at 77 sites along 150 km of coastline with different natural features and degrees of human influence using a combination of seine nets and surf-BRUVS. We used generalized additive models (GAMs) to investigate the influence of environmental variables and urbanization on taxonomic and functional diversity of resident fish assemblages. Main results:We found that significant breaker wave height was the most important environmental variable in explaining the taxonomic and functional diversity of fish assemblages. The effects of increasing wave height were mostly negative, except for piscivorous fishes, which were most abundant at high energy sites, and for benthic and zoobenthivorous species, which were most abundant at sites with intermediate wave exposure. The latter species were also associated with higher chlorophyll-a contributing to increased taxonomic richness and abundance. Further, anthropogenic impacts generally reduced diversity, with highest diversity only observed at the most pristine sites. Main conclusions:Our results demonstrate that both natural environmental variation and human activities structure the fish assemblages of sandy beach surf zones,

show abstract

“…Therefore, the conservation of these urban-tolerant species is essential to ensure the continued ecological functioning of the system. Although modified estuaries may still maintain ecosystem functioning, poor water quality significantly reduces their resilience (Yabsley et al, 2020). The current study clearly depicted the consequences of excessive nutrient input to the uMgeni Estuary via artificial LULC in the 20 m estuarine functional zone.…”

Section: Contributions and Recommendations For Estuarine Managementmentioning

confidence: 62%

“…Although agriculture does contribute nutrient input to the system, regular flushing and strong tidal mixing remove excess nutrients and detritus. Yabsley et al (2020) showed that estuaries that receive high nutrient loads and simultaneously exhibit largely natural habitats such as mangroves contain high species abundances, characteristics also present in the uMlalazi Estuary.…”

Section: Historic Community Assemblagementioning

confidence: 99%

Decadal changes in land-use, water quality and fish assemblages in a KwaZulu-Natal urban and non-urban estuary.

Van Schoor

View full text Add to dashboard Cite

Globally, estuaries are recognised as highly dynamic environments which support diverse and productive flora and fauna, and provide numerous goods and services for human wellbeing.These systems are under threat from growing coastal populations that demand the transformation of natural land to accommodate urbanisation, agriculture, harbour, and infrastructure developments. Direct and indirect land-use/land-cover (LULC) changes adversely affect estuarine water quality, directly impacting estuarine biota such as fishes.While the short links between these components are known, few studies have attempted to integrate these links, particularly within the South African context. Therefore, this study aimed to integrate different levels of assessment (LULC and estuarine water quality) to describe changes in estuarine fish ecology over space and time. The study compared two permanently open estuaries in KwaZulu-Natal with distinct land-cover types, namely the uMgeni and uMlalazi estuaries. The uMgeni Estuary is surrounded by urban features and is situated in a highly developed catchment, whereas the uMlalazi is near-natural, with some surrounding agricultural areas.Historical land-cover imagery from the estuary to the 20 m topographical contour (inclusive of the Estuary Functional Zone), the estuary catchment land-cover, water quality and ichthyofauna data were collected. Land-cover types were grouped into eight categories and 42 feature classes based on modifications to the South African National Land Cover system, the United States Geological Survey and the Coastal Change Analysis Program. Multivariate statistical analysis identified two distinct groupings of land-cover types, Period 1 (before 1989) and Period 2 (during and after 1989). This period factor was then further used throughout the study to determine associated (temporal) responses in water quality and fish assemblages. Strong negative correlations were observed between dissolved oxygen and artificial land-cover types in the uMgeni Estuary. The results suggested that the uMgeni Estuary receives nutrient inputs from various urban activities, which reduce oxygen levels within the water column. Alterations to the hierarchical ichthyofauna structure in the uMgeni occurred on a year to year basis, relative to these anthropogenic impacts. In contrast, good water quality likely associated with fewer developments within the Estuarine Functional Zone has allowed the hierarchical fish structure in the uMlalazi Estuary to remain the same over time, although minor species level differences have occurred.

show abstract

Landscape context and nutrients modify the effects of coastal urbanisation

Cited by 11 publications

References 185 publications

The utility of non‐lethal morphometrics to evaluate fish condition

The utility of non‐lethal morphometrics to evaluate fish condition

Revealing the drivers of taxonomic and functional diversity of nearshore fish assemblages: Implications for conservation priorities

Decadal changes in land-use, water quality and fish assemblages in a KwaZulu-Natal urban and non-urban estuary.

Contact Info

Product

Resources

About