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Fit of generalized linear models (GLMs) to assess the relationships of trophic niche size (volume) with spatial habitat (a) configuration (fragmentation index) and (b) amount (seascape cover). See Table 2a,b for more details on the GLMs
Source publication
Habitat fragmentation of submerged aquatic vegetation (SAV) transforms the spatial pattern of seascapes by changing both the total area and spatial configuration of the habitat patches. The ecological effects of SAV seascapes are most often assessed using metrics of biological community composition (e.g., species and assemblage changes). We know co...
Citations
... Lower habitat connectivity has also been shown to decrease the conversion of primary production into consumer biomass, lowering overall ecosystem productivity (Cloern et al. 2007). In seagrass sys-tems, pinfish Lagodon rhomboides tend to have larger trophic niches in areas with low seagrass cover (lower productivity) and increased fragmentation, which decrease connectivity between habitat patches (Santos et al. 2022). Thus, decreased seascape connectivity at Dean Creek, resulting from higher marsh edge elevation and lower channel density, could be indicative of lower ecosystem productivity and correspond to larger trophic niches of taxa observed at this site. ...
Across relatively small spatial scales, differences in seascape structure may influence how species transverse adjacent habitats, with effects on trophic relationships and energy flow dynamics. To understand the effects of seascape structure, we used stable isotope analysis to examine variation in resource use by 2 highly abundant estuarine species, mummichogs Fundulus heteroclitus and grass shrimp Palaemon spp., both of which are known to forage in intertidal areas. We compared the percent contribution of basal resources, trophic position, and trophic niches of mummichogs and grass shrimp from 2 tidal creeks with differing seascape structure located ~10 km apart on Sapelo Island, Georgia, USA. Belle Marsh creekbank edge elevation was on average 0.5 m lower and channel density was 5 times greater than Dean Creek, potentially influencing marsh platform access. Although we found no difference in the contribution of marsh-derived energy to grass shrimp among sites, the contribution of marsh-derived energy to mummichogs was on average 1.9 times higher at Belle Marsh. In addition, both species had higher trophic positions and larger trophic niches at Dean Creek, suggesting a less efficient route of energy transfer to consumer production. There was also little overlap in trophic niche among sites for either species. Our results suggest that species traits, site characteristics, and their interaction may influence resource use by intertidal estuarine consumers. By examining how marsh resource use by estuarine consumers varies across multiple marshes with differing morphologies, we can better predict and quantify how seascape structure may affect secondary productivity of estuarine systems.
... E-scapes). IEI values were combined with habitat cover areas within a landscape foraging unit (grid cell with an area that corresponds to the movement range of the consumer; James, Santos, Rehage, et al., 2022) to calculate the HRI. HRI was calculated with the following formula: ...
... Additionally, pink shrimp was the only species with an IEI value >1 for a basal resource that was unaffected by the die-off (algae, , and it is possible that seagrass consumers in Florida Bay had a similar response. Additionally, resource distribution influences variability in resource use and competition between species Santos et al., 2022), as well as consumer movement and distribution (Abrahms et al., 2019(Abrahms et al., , 2021Geary et al., 2020). ...
Natural and anthropogenic disturbances have led to rapid declines in the amount and quality of available habitat in many ecosystems. Many studies have focused on how habitat loss has affected the composition and configuration of habitats, but there have been fewer studies that investigate how this loss affects ecosystem function. We investigated how a large‐scale seagrass die‐off altered the distribution of energetic resources of three seagrass‐associated consumers with varied resource use patterns. Using long‐term benthic habitat monitoring data and resource use data from Bayesian stable isotope mixing models, we generated energetic resource landscapes ( E‐ scapes) annually between 2007 and 2019. E‐ scapes link the resources being used by a consumer to the habitats that produce those resources to calculate a habitat resource index as a measurement of energetic quality of the landscape. Overall, our results revealed that following the die‐off there was a reduction in trophic function across all species in areas affected by the die‐off event, but the response was species‐specific and dependent on resource use and recovery patterns. This study highlights how habitat loss can lead to changes in ecosystem function. Incorporating changes in ecosystem function into models of habitat loss could improve understanding of how species will respond to future change.
... One of the major criticalities concerning the application of landscape ecology to marine and coastal environment has been the clear identification of habitats boundaries and their mapping. Current advances in marine remote sensing technologies are progressively facilitating this task, especially in intertidal and shallow areas Wedding et al., 2011;Bell and Furman, 2017), with the result that most applications are focused on intertidal/benthic habitat types mainly located in coastal areas, such as salt marshes, seagrasses, coral reefs and macroalgae (Wedding et al., 2011;James et al., 2021;Santos et al., 2022), with only very recent studies going beyond this limit (Swanborn et al., 2022b, a). Although the appropriateness of the transposition of terrestrial methodologies to aquatic ecosystems is still debated (Manderson, 2016;Bell and Furman, 2017), the analysis of seascape structure mostly relies on the use of metrics designed for terrestrial ecosystems (Wedding et al., 2011), which are used to describe characteristics of the habitats mosaics. ...
... influencing the faunal assemblages and a variety of marine ecological processes (Sekund and Pittman, 2017;Abadie et al., 2018;Santos et al., 2018Santos et al., , 2022James et al., 2021). The Venice lagoon does not make an exception in this sense: it is poorly studied from a seascape ecology perspective, but first evidences suggest a link between habitats' spatial patterns, fish assemblages and local fisheries (Scapin et al., 2018(Scapin et al., , 2022. ...
The relationships between habitat patterns and ecosystem functioning have been widely explored in terrestrial ecosystems, but less in marine and coastal ecosystems, calling for further research in this direction. This work focuses on the mosaic of submerged habitats in the Venice lagoon, Italy. It aims to describe the habitats’ spatial patterns at multiple spatial scales, and to explore their linkages with the ecological status defined according to the EU Water Framework Directive (WFD, 2000/60/EC). The submerged habitats’ mosaic has been analysed by calculating a set of seascape metrics at different spatial scales. These metrics have been linked with the biological quality elements (BQEs) that are monitored in the lagoon in compliance to the WFD. The results show that the habitats’ spatial patterns differ between the areas of the lagoon with marine-like features and the areas which still retain more lagoon characteristics. The similarity between the pattern found in the whole lagoon and those found in marine-like areas suggests a general loss of lagoon characteristics at the lagoon scale. Regarding the ecological status, every BQE seems to be associated with a different habitat configuration at the water body scale. This does not facilitate the joint improvement of the BQEs, as required by the Directive. If we cannot achieve that, at some point we will probably have to choose what to prioritize. On a broader perspective, this calls for a reflection on what lagoon we want for the future, a vision that should be shared and account for the lagoon’s complexity, current trends and challenges.
... The assessment of widespread and patchy habitat such as CDB requires a seascape approach. It is known that the seascape can directly influence the trophic network and the ecosystem functioning (Boström et al., 2011;Abadie et al., 2018;Santos et al., 2022). In the light of that, a seascape approach should be a potential suitable descriptor to assess the quality of an ecosystem (e.g., marine forests, habitat structure, etc.; Chemineé et al., Thiriet et al., 2014). ...
Introduction
Coastal detrital bottoms (CDB) are one of the most extensive habitats of the continental shelf worldwide, in the upper levels of the circalittoral zone. Hosting a diverse community structured by sediment grain size, trophic interactions and calcified organisms, CDB exhibit important ecological functions. In the Mediterranean Sea, CDB are constituted by recent elements partly provided by adjacent infralittoral and circalittoral ecosystems. Since the 2010s, the offshore extension of many Marine Protected Areas (MPAs) has resulted in the incorporation of vast areas of CDB, raising the issue of their management. The Marine Strategy Framework Directive (MSFD) has embraced the concept of an ecosystem-based approach involving taking into account the functioning of marine habitats and their related ecosystem services. The purpose of this paper is to propose an ecosystem-based quality index (EBQI) tested on CDB from the north-western Mediterranean Sea, focusing mainly on epibenthic assemblages.
Methods
The first step has been to define a conceptual model of the CDB functioning, including the main trophic compartments and their relative weighting, then to identify appropriate assessment methods and potential descriptors. Twenty-nine sites were sampled along the coast of Provence and French Riviera (Southern France). Study sites were chosen with a view to encompassing a wide range of hydrological conditions and human pressures.
Results
Very well-preserved sites were found in Provence in areas without trawling and terrigenous inputs, while impacted and low-ES sites were located in the vicinity of urbanized areas. The cover of rhodoliths characterizes the seascape and might be an indicator of the good ES of CDB and reduced human pressure. However, the absence of rhodoliths may also be induced by natural phenomena.
Discussion
The EBQI designed for CDB proved representative and useful for a functional assessment based on epibenthic assemblages. However, some descriptors have shown their limitations and should be further explored. We highlight here the priority of establishing an index corresponding to a societal demand (e.g., European Directives, Barcelona convention) as a basis for a broad and large-scale assessment, for practical reasons. We stress the need to better apprehend the role of the macro-infauna and to extend this index over a wider geographical scale.
... Blank ('-') minimum and maximum values for anthropogenic disturbances indicate that variables were not included in the analyses at the respective scale The fragmentation metrics used in this study were types of spatial pattern metrics, which are routinely applied to quantify changes in the composition and configuration of patches in both landscape (McGarigal, Cushman & Regan, 2005;Schindler et al., 2013) and seascape ecology (Sleeman et al., 2005;Wedding et al., 2011;Swadling et al., 2019). The fragmentation metrics selected (Table 1) were patch density (PD), landscape division (LD), area-weighted mean perimeter to area ratio (AWMPAR) and mean radius of gyration (2016) and Santos et al. (2022), but was adapted to include the number of holes metric as follows: ...
... GYRATE), which have been recommended by others(Sleeman et al., 2005;Santos, Lirman & Pittman, 2016;Santos et al., 2022).These metrics quantify four different characteristics of habitat fragmentation which include habitat extent, compactness, subdivision and configuration, and are relative across spatial scales, habitat coverage and aggregation(McGarigal, 2001;McGarigal, Cushman & Regan, 2005;Sleeman et al., 2005;Santos, Lirman & Pittman, 2016).All these metrics became larger with increased fragmentation except GYRATE, which decreased with increased fragmentation.Fragmentation metrics were quantified using the landscapemetrics package in the statistical software R(Hesselbarth et al., 2019). For more information on the behaviour of the fragmentation metrics please seeFigure S1and the formulae used to calculate the metrics with the package landscapemetrics can be found at https://rspatialecology.github.io/landscapemetrics/index.html. ...
• Although it is well established that human activities are linked to the loss of seagrasses worldwide, the influence of anthropogenic disturbances on the habitat fragmentation of seagrass meadows is less understood. This information is essential to identify how humans are modifying seascapes and what disturbances pose the greatest risk to seagrasses, which is pertinent given the rapid urbanization occurring in coastal areas.
• This study examined how the habitat fragmentation of an endangered seagrass Posidonia australis varied in relation to several anthropogenic disturbances (i.e. human population, marine infrastructure, terrestrial run-off and catchment land-usage) within 10 estuaries across 620 km of coastline in New South Wales, Australia.
• When comparing between estuaries, the fragmentation of P. australis meadows was significantly greater in estuaries adjacent to highly populated metropolitan centres – generally in the Greater Sydney region. At sites within estuaries, the density of boat moorings was the most important predictor of habitat fragmentation, but there was also evidence of higher fragmentation with increased numbers of jetties and oyster aquaculture leases.
• These results suggest that the fragmentation of seagrass meadows will become more pervasive as the human population continues to grow and estuarine development increases. Strategies to mitigate anthropogenic disturbances on seagrass meadow fragmentation could include prohibiting the construction of boat moorings and other artificial structures in areas where seagrasses are present or promoting environmentally friendly designs for marine infrastructure. This knowledge will support ongoing management actions attempting to balance coastal development and the conservation of seagrasses.
... seagrass) leads to a loss in secondary production unless consumers compensate by altering basal resource use (Deegan and Garritt, 1997;Smith et al., 2008;Lesser et al., 2020). For example, seagrass omnivores increase variation in basal resource use to compensate for lower production (Lesser et al., 2020;Santos et al., 2022). Habitat loss can also alter species interactions by increasing competition for space and resources and changing prey capture efficiency (Hovel and Lipcius, 2001;Fahrig, 2003;Canion and Heck, 2009). ...
... Instead, consumers might concentrate foraging effort into the remnant patches of seagrass, thus increasing competition, with possible negative effects on secondary production (Macreadie et al., 2010). Consumers might also increase movement and home range size or increase variation in resource use in response to lower amounts of basal resources following the die-off in order to meet energetic demands (Schradin et al., 2010;Lesser et al., 2020;Santos et al., 2022). Alternatively, consumers might display shifts in basal resource use immediately following disturbance but display rapid recovery in the timeframe before sampling occurred. ...
... Spatial variation in production, habitat amount, habitat configuration, and environmental factors (e.g. depth, salinity) have all been shown to affect resource use (Livingston, 1984;Deegan and Garritt, 1997;Olin et al., 2012;Nelson et al., 2015;Giraldo et al., 2017;Jankowska et al., 2018;Santos et al., 2022). Our results do not point to these factors influencing basal resource use of seagrass, epiphytes, mangroves, or algae in the wet season as there is little intraspecific spatial variation among the sites sampled, despite broad spatial sampling (Table 3, S1, Figure 4). ...
Macrophyte foundation species provide both habitat structure and primary production, and loss of these habitats can alter species interactions and lead to changes in energy flow in food webs. Extensive seagrass meadows in Florida Bay have recently experienced a widespread loss of seagrass habitat due to a Thalassia testudinum mass mortality event in 2015 associated with prolonged hypersalinity and bottom-water anoxia. Using stable isotope analysis paired with Bayesian mixing models, we investigated the basal resource use of seven species of seagrass-associated consumers across Florida Bay in areas affected by the 2015 seagrass die-off. Three years after the die-off, basal resource use did not differ for species collected inside and outside the die-off affected areas. Instead, consumers showed seasonal patterns in basal resource use with seagrass the most important in the wet season (58%), while epiphytes were the most important in the dry season (44%). Additionally, intraspecific spatial variability in resource use was lower in the wet season compared to the dry season. We were unable to detect a legacy effect of a major disturbance on the basal resource use of the most common seagrass-associated consumers in Florida Bay.
... Environments with predictable pulses in resources would therefore be expected to support a low specialization in space use due to the quantity of resources available for individuals and consequently decreasing the trophic niche size 12,47,[49][50][51] . Conversely, an expansion in the trophic niche can be expected via foraging on different prey resources, which could result from the increase of intra-specific variance in space use or high specialization [52][53][54] . ...
... Snook niches were larger when snook had less specialized space use. This result contradicted our original prediction that higher spatial clustering in space by the consumer (i.e., low space use specialization), due to the concentration of preferable prey resources, would result in smaller trophic niche sizes 50,51,54 . For instance, lower water levels in marshes connected to the SR are associated with a low space use specialization for snook, which rely mostly on freshwater prey subsidies originating from the marshes. ...
... These subsidies increase the amount of energy available 7,57,77 , increasing snook body condition and reproductive output 86 . In other systems, increased production has been shown to lead to decreases in the trophic niche size of consumers 54,101 . Higher availability of prey resources with a high potential of contributing energetically to consumers can reduce species' trophic niche size by buffering intra-and inter-specific competition, and allowing individuals to specialize in common sources of energy 39,46,102 . ...
Variability in space use among conspecifics can emerge from foraging strategies that track available resources, especially in riverscapes that promote high synchrony between prey pulses and consumers. Projected changes in riverscape hydrological regimes due to water management and climate change accentuate the need to understand the natural variability in animal space use and its implications for population dynamics and ecosystem function. Here, we used long-term tracking of Common Snook (Centropomus undecimalis) movement and trophic dynamics in the Shark River, Everglades National Park from 2012 to 2023 to test how specialization in the space use of individuals (i.e., Eadj) changes seasonally, how it is influenced by yearly hydrological conditions, and its relationship to the between individual trophic niche. Snook exhibited seasonal variability in space use, with maximum individual specialization (high dissimilarity) in the wet season. The degree of individual specialization increased over the years in association with greater marsh flooding duration, which produced important subsidies. Also, there were threshold responses of individual space use specialization as a function of floodplain conditions. Greater specialization in space use results in a decrease in snook trophic niche size. These results show how hydrological regimes in riverscapes influence individual specialization of resource use (both space and prey), providing insight into how forecasted hydroclimatic scenarios may shape habitat selection processes and the trophic dynamics of mobile consumers.
The relationships between habitat patterns and ecosystem functioning have been widely explored in terrestrial ecosystems, but less in marine and coastal ecosystems, calling for further research in this direction. This work focuses on the mosaic of submerged habitats in the Venice lagoon, Italy. It aims to describe the habitats’ spatial patterns at multiple spatial scales, and to explore their linkages with the ecological status defined according to the EU Water Framework Directive (2000/60/EC). The submerged habitats’ mosaic has been analysed by calculating a set of seascape metrics at different spatial scales. These metrics have been linked with the biological quality elements (BQEs) that define the ecological status in the lagoon. The results show that the habitats’ spatial patterns differ between the areas of the lagoon with marine-like features and the areas which still retain more lagoon characteristics. The similarity between the pattern found in the whole lagoon and those found in marine-like areas suggests a general loss of lagoon characteristics at the lagoon scale. Regarding the ecological status, every BQE seems to be associated with a different habitat configuration at the water body scale. This does not facilitate the joint improvement of the BQEs, as required by the Directive. If we cannot achieve that, at some point we will probably have to choose what to prioritize. On a broader perspective, this calls for a reflection on what lagoon we want for the future, a vision that should be shared and account for the lagoon’s complexity, current trends and challenges.
Seagrass beds in Florida Bay are home to many ecologically and economically important species. Anthropogenic press perturbation via alterations in hydrology and pulse perturbations such as drought can lead to hypersalinity, hypoxia, and sulfide toxicity, ultimately causing seagrass die-offs. Florida Bay has undergone two large-scale seagrass die-offs, the first in the late 1980s and early 1990s and the second in 2015. Post-die-off events, samples were collected for stable isotope analysis. Using historical (1998–1999) and contemporary (2018) stable isotope data, we examine how food webs in Florida Bay have changed in response to seagrass die-off over time by measuring contributions of basal sources to energy usage and using trophic niche analysis to compare niche size and overlap. We examined three consumer species sampled in both time periods (Orthopristis chrysoptera, Lagodon rhomboides, and Eucinostomus gula) in our study. Seagrass production comprised the majority of source usage in both datasets. However, contemporary consumers had a mean increase of 18% seagrass usage and a mean decrease in epiphyte usage of 7%. The shift in trophic niche from epiphyte usage (green pathway) toward seagrass usage (brown pathway) may indicate that food web browning is occurring in Florida Bay.
