Fitness consequences of habitat variability,trophic position,and energy allocation across the depth distribution of a coral-reef fish

Environmental clines such as latitude and depth that limit species’ distributions may be associated with gradients in habitat suitability that can affect the fitness of an organism. With the global loss of shallow-water photosynthetic coral reefs, mesophotic coral ecosystems (~30–150 m) may be buffered from some environmental stressors, thereby serving as refuges for a range of organisms including mobile obligate reef dwellers. Yet habitat suitability may be diminished at the depth boundary of photosynthetic coral reefs. We assessed the suitability of coral-reef habitats across the majority of the depth distribution of a common demersal reef fish (Stegastes partitus) ranging from shallow shelf (SS, <10 m) and deep shelf (DS, 20–30 m) habitats in the Florida Keys to mesophotic depths (MP, 60–70 m) at Pulley Ridge on the west Florida Shelf. Diet, behavior, and potential energetic trade-offs differed across study sites, but did not always have a monotonic relationship with depth, suggesting that some drivers of habitat suitability are decoupled from depth and may be linked with geographic location or the local environment. Feeding and diet composition differed among depths with the highest consumption of annelids, lowest ingestion of appendicularians, and the lowest gut fullness in DS habitats where predator densities were highest and fish exhibited risk-averse behavior that may restrict foraging. Fish in MP environments had a broader diet niche, higher trophic position, and higher muscle C:N ratios compared to shallower environments. High C:N ratios suggest increased tissue lipid content in fish in MP habitats that coincided with higher investment in reproduction based on gonado-somatic index. These results suggest that peripheral MP reefs are suitable habitats for demersal reef fish and may be important refuges for organisms common on declining shallow coral reefs.

     

Size-related shifts in the habitat associations of young-of-the-year winter flounder (Pseudopleuronectes americanus): field observations and laboratory experiments with sediments and prey

Field surveys and laboratory studies were used to determine the role of substrata in habitat selection by young-of-the year winter flounder. A synoptic field survey of winter flounder and sediments in the Navesink River-Sandy Hook Bay estuarine system in New Jersey demonstrated that winter flounder distribution was related to sediment grain size. Analysis using a generalized additive model indicated that the probability of capturing 10-49 mm SL winter flounder was high on sediments with a mean grain diameter of /=40 mm SL) preferred coarse-grained sediments. Burying ability increased with size and all flounders avoided sediments that prevented burial. Subsequent laboratory experiments revealed that the presence of live prey (Mya arenaria) can over-ride sediment choice by winter flounder (50-68 mm SL) indicating the complexity of interrelated factors in habitat choice.     

Effects of a predatory fish (Galaxias olidus) on the structure of intermittent stream pool communities in southeast Australia

Abstract The impact of predation over a 3 week period by the small (mean length 53 mm) salmoniform fish, Galaxias olidus, on the invertebrate communities in the still summer pools of an intermittent stream in southeastern Australia was tested using enclosures that incorporated both deep and shallow habitat areas. Twenty G. olidus, a key generalist predator in the system studied, were enclosed for 3 weeks in 1.5 × 1.7 m enclosures. Galaxias olidus was found to reduce significantly the distribution and abundance of air-breathing nektonic species. In contrast, the abundance of non-air-breathing nektonic species increased in the presence of fish in the deep areas of the enclosures. There was no significant impact offish predation on species richness, total abundance, epibenthic or interstitial species. The most likely reason for the general lack of response to the presence of fish by epibenthic and interstitial species is the availability of abundant spatial refugia from predation within the complex substrate of the stream. In contrast, air-breathing nektonic species are vulnerable to predation by fish due to the lack of refuges in the open water. Increases in the abundance of non-air-breathing nektonic species in the presence of fish may be related to reductions in the abundance of predatory dytiscid beetles. Significant differences between deep and shallow habitats were observed in total abundance and species richness, and in the abundances of air-breathing nektonic and epibenthic species, suggesting that physicochemical factors play a key role in determining invertebrate distribution within stream pools.     

Larval growth history determines juvenile growth and survival in a tropical marine fish

Processes that occur around the transition between larval and juvenile life‐stages can have a major effect on the population dynamics of organisms with complex life cycles. We explore the roles of larval history and selective post‐settlement mortality in determining the growth and survival of newly settled individuals of the damselfish, Pomacentrus amboinensis (Pomacentridae). Specifically, we determine whether the direction and intensity of selection on the recruits differs among various size‐classes of predators. A mark‐recapture study showed that individuals who survived 9 or more days were significantly larger at settlement than those that died within the first day (12.3 vs 11.9 mm SL), when mortality was highest (25% d^?1). Censuses revealed that the species and size composition of piscivores differed markedly between two reef habitats where P. amboinensis was common. A cage experiment, conducted in both habitats, manipulated the sizes of predators that could access newly settled P. amboinensis to determine whether the resulting mortality of the recently settled fish was influenced by larval growth history or size at settlement. Ten days after the start of the experiment individuals that grew slowly in the second half of their larval life had been lost from most of the experimental treatments. Small fish were also selectively lost from the coarse‐mesh cage on the reef base. Significant positive relationships between pre‐ and post‐settlement growth rates were found in both habitats for the fine mesh cages, cage controls and open patch reefs. This relationship was reversed in the coarse mesh cages in both habitats. This growth compensation was facilitated through the action of a particular size range of predators, whose impact was disrupted or masked in the open treatments by the action of a diverse predator pool. The present study underscores the complexity of the processes that influence the early post‐transition growth and survival in organisms with complex life‐histories.     

The effects of seafloor habitat complexity on survival of juvenile fishes: Species-specific interactions with structural refuge

Marine fishes are often associated with structurally complex microhabitats that are believed to provide a refuge from predation. However, the effects of habitat complexity on predator foraging success can be strongly modified by predator and prey behaviors. We conducted a series of laboratory experiments to evaluate the effects of sea floor habitat complexity on juvenile fish survivorship using multiple predator (striped searobin and summer flounder) and prey (winter flounder, scup, and black sea bass) species to identify potentially important species-habitat interactions. Three habitats of varying complexity (bare sand, shell, and sponge) common to coastal marine environments were simulated in large aquaria (2.4 m diameter, 2400 L volume). Prey survivorship increased significantly with greater habitat complexity for each species combination tested. However, examination of multiple prey and predator species across habitats revealed important effects of predator × habitat and prey × habitat interactions on prey survival, which appeared to be related to species-specific predator and prey behavior in complex habitats. Significant species × habitat interactions imply that the impact of reduced seafloor habitat complexity may be more severe for some species than others. Our results indicate that the general effects of seafloor habitat complexity on juvenile fish survivorship may be broadly applicable, but that the interaction of particular habitats with search tactics of predators as well as habitat affinities and avoidance responses of prey can produce differences among species that contribute to variable mortality.     

Small-scale patterns in distribution and feeding of Atlantic mackerel (Scomber scombrus L.) larvae in the Celtic Sea with special regard to intra-cohort cannibalism

Short-term variability in vertical distribution and feeding of Atlantic mackerel (Scomber scombrus L.) larvae was investigated while tracking a larval patch over a 48-h period. The patch was repeatedly sampled and a total of 12,462 mackerel larvae were caught within the upper 100 m of the water column. Physical parameters were monitored at the same time. Larval length distribution showed a mode in the 3.0 mm standard length (SL) class (mean abundance of 3.0 mm larvae =75.34 per 100 m³, s=34.37). Highest densities occurred at 20–40 m depth. Larvae <5.0 mm SL were highly aggregated above the thermocline, while larvae ≥5.0 mm SL were more dispersed and tended to migrate below the thermocline. Gut contents of 1,177 mackerel larvae (2.9–9.7 mm SL) were analyzed. Feeding incidence, mean number (numerical intensity) and mean dry weight (weight-based intensity) of prey items per larval gut were significantly dependent on larval size. However, while weight-based feeding intensities continued to increase with larval length, numerical intensity peaked at 4–4.9 mm SL, indicating a shift in the larval diet. While first-feeding larvae relied most heavily on copepod nauplii and eggs, larvae ≥5.0 mm SL initiated piscivorous feeding. All identifiable fish larvae were Atlantic mackerel. Thus, the piscivory was cannibalism. Larval feeding incidence and numerical feeding intensities peaked during daytime and were reduced at night. Daily ration estimates for first-feeding mackerel larvae <4.0 mm SL were extremely low = 1.43% body dry weight, but increased dramatically at 5.0 mm SL, i.e., at the onset of cannibalism, reaching >50% body dry weight in larva ≥8.0 mm SL. Received in revised form: 31 October 2000 Electronic Publication     

Effects of water depth and hydrodynamics on the growth and distribution of juvenile cyprinids in the littoral zone of a large pre-alpine lake

In enclosure experiments in the littoral zone of Lake Constance, Germany, juvenile cyprinids showed significantly reduced somatic growth in the shallow eulittoral zone (0·5 m depth) compared to the sublittoral zone (1·6 m depth). Growth was especially reduced in larger and more deep-bodied fish groups, providing evidence that this is due to increased hydrodynamic stress, induced by ship and wind waves, in the shallow habitats compared to the deep habitat. Other factors such as water temperature and food availability seemed to be of minor importance for the observed growth differences. Gillnet catches at the experimental site and an adjacent site showed that most juvenile cyprinids, including the species from the enclosure study, bream Abramis brama and dace Leuciscus leuciscus , nonetheless prefer shallow habitats compared to deeper sublittoral habitats. Juvenile cyprinids in Lake Constance may prefer these shallow habitats as refuges against larger piscivorous predators, mainly perch Perca fluviatilis , despite the cost in terms of reduced somatic growth indicating that juvenile cyprinids first of all optimize survival rate instead of somatic growth rate.     

Effects of the toxic dinoflagellate, Alexandrium fundyense on three species of larval fish: a food-chain approach

Sublethal behavioural effects of exposure to paralytic shellfish toxins (PST; saxitoxin and its derivatives) from the toxic dinoflagellate Alexandrium fundyense were investigated in newly settled winter flounder Pseudopleuronectes americanus , larval sheepshead minnow Cyprinodon variegatus and larval mummichog Fundulus heteroclitus through an A. fundyense –copepod–fish food chain. Consumption of as few as six to 12 toxin-containing copepods was lethal to the fishes. After consuming fewer toxin-containing copepods, all three fish species exhibited sublethal effects from vector-mediated exposure. Prey-capture ability of mummichogs was reduced in larvae that had consumed toxic copepods, Coullana canadensis . After consuming toxic C. canadensis or mixed copepods, mummichog larvae had reduced swimming performance. Swimming activity was also significantly reduced in winter flounder after consuming toxic copepods, including time spent in motion and distance travelled. Prey capture and predator avoidance were reduced in first-feeding sheepshead minnow larvae that had consumed toxic dinoflagellate cells. Adverse effects on prey capture or predator avoidance may reduce larval survival and facilitate the transmission of PST through the food web. This study provides baseline information on sublethal effects of PST exposure on fishes using a novel food-chain approach with zooplankton as vectors.     

Intraspecific interactions influence size specific depth distribution in Cottus bairdi

Synopsis We tested depth selection by different sizes of mottled sculpin, Cottus bairdi, in a southern Appalachian stream. Field observations indicated that, during one hour periods, both small (<50 mm SL) and large (≥55 mm SL) individuals move within an area less than 0.50 m². Individuals of both sizes, placed in field enclosures, preferred deep microhabitat. When large fish were placed in cages with small fish, small fish initially spent more time in slope and shallow microhabitats. Average interfish distances were not correlated with their absolute size differences, suggesting C. bairdi interactions may involve both predation and competition. In streams, size-related differences in microhabitat depth may result more from intraspecific interactions than from size-specific depth preferences.     

Vertical distribution of Atlantic salmon (Salmo salar) as a function of illumination

The vertical distribution of cultured Atlantic salmon larger than 1 kg was monitored by hydroacoustics in both a shallow (6 m) and a deep (20 m) cage. Surface light levels and fish distribution were registered for three periods throughout the year. The two fish groups were fed calculated rations twice a day. During the winter and spring (including vernal equinox), the fish were distributed at around 5 m depth in both cages when not feeding. Around summer solstice, the fish preferred deeper waters when not feeding. The light dependency of the vertical migration was pronounced, and indicates clearly that even a 20 m deep cage is not deep enough to meet the depth requirements of large Atlantic salmon during summer.     

The role of deep reefs in shallow reef recovery: an assessment of vertical connectivity in a brooding coral from west and east Australia

Approximately one quarter of zooxanthellate coral species have a depth distribution from shallow waters (<30 m) down to mesophotic depths of 30-60 m. The deeper populations of such species are less likely to be affected by certain environmental perturbations, including high temperature/high irradiance causing coral bleaching. This has led to the hypothesis that deep populations may serve as refuges and a source of recruits for shallow reef habitats. The extent of vertical connectivity of reef coral species, however, is largely unquantified. Using 10 coral host microsatellite loci and sequences of the host mtDNA putative control region, as well as ribosomal DNA (rDNA) ITS2 sequences of the coral's algal endosymbionts (Symbiodinium), we examine population structure, connectivity and symbiont specificity in the brooding coral Seriatopora hystrix across a depth profile in both northwest (Scott Reef) and northeast Australia (Yonge Reef). Strong genetic structuring over depth was observed in both regions based on the microsatellite loci; however, Yonge Reef exhibited an additional partitioning of mtDNA lineages (associated with specific symbiont ITS2 types), whereas Scott Reef was dominated by a single mtDNA lineage (with no apparent host-symbiont specificity). Evidence for recruitment of larvae of deep water origin into shallow habitats was found at Scott Reef, suggesting that recovery of shallow water habitats may be aided by migration from deep water refuges. Conversely, no migration from the genetically divergent deep slope populations into the shallow habitats was evident at Yonge Reef, making recovery of shallow habitats from deeper waters at this location highly unlikely.     

Sinking rates of late-stage fish larvae: Implications for larval ingress into estuarine nursery habitats

Many species spawn in oceanic waters yet their juvenile stages use nearshore and estuarine habits and the bio-physical mechanisms by which late-larvae enter these juvenile habitats may be an important bottleneck in the population dynamics of these species. To provide parameters for the development of larval ingress models, sinking rates were measured of the late-stage larvae of six fish species: Atlantic croaker (Micropogonias undulatus), spot (Leiostomus xanthurus), Atlantic menhaden (Brevoortia tyrannus), summer flounder (Paralichthys dentatus), southern flounder (P. lethostigma), and gulf flounder (P. albigutta). Species-specific differences were found in sinking rates; Atlantic croaker had the slowest sinking rates and Atlantic menhaden and the three flounder species had the fastest sinking rates. Additionally, sinking rates increased for all species as length increased. The total amount of variability explained in sinking rates was low (20–50%), indicating a large amount of variability at the level of the individual. The observed patterns in sinking rates were then combined with previous studies on the mechanisms of larval ingress to present species-specific conceptual models of ingress.     

Shelter selection in juvenile Atlantic salmon,or why do salmon seek shelter in winter?

During winter, juvenile Atlantic salmon Salmo salar become nocturnal and seek refuge during the day in the stream bed gravel interstitial spaces. The function of this behaviour is unclear, but two major types of hypothesis have been proposed. One is that the fish are hiding from something (e.g. a predator) and the other is that the fish are seeking shelter from the water current. These hypotheses were tested by examining the selection of juvenile salmon for refuges that offered different degrees of concealment or shelter. The fish clearly preferred refuges that allowed them to hide (i.e. they were dark and opaque) but offered little shelter from the current. Therefore, it can be assumed that the primary function of this nocturnal behaviour during winter is most likely to hide from diurnal predators.     

Timing and sites of parturition of the viviparous scorpionfish, Sebastiscus marmoratus

Timing and sites of parturition of the viviparous scorpionfish Sebastiscus marmoratus were investigated both in aquaria and natural habitats of a rocky coast in southern Japan. Females released 4 mm TL larvae during the early night in winter. Night spawning may be advantageous in avoiding predators of both larvae and spawners, because most such predators are inactive during the night. Females inhabiting shallow areas (< 6 m depth) moved to deeper sites for parturition, but ones inhabiting deeper areas (6–8 m depth) gave birth within their usual habitats. This migration may be advantageous in effective larval dispersal.     

Predator-prey relations between age-1+ summer flounder (Paralichthys dentatus, Linnaeus) and age-0 winter flounder (Pseudopleuronectes americanus, Walbaum): predator diets, prey selection, and effects of sediments and macrophytes

Laboratory experiments and weekly trammel net surveys in the Navesink River, New Jersey (USA) were used to examine the predator-prey interaction between age-1+ summer flounder (Paralichthys dentatus) and age-0 winter flounder (Pseudopleuronectes americanus). Winter flounder (24-67 mm TL) were the dominant piscine prey of summer flounder (n=95, 252-648 mm TL) collected in trammel nets. We observed a temporal shift in summer flounder diets from sand shrimp (Crangon septemspinosa) and winter flounder, dominant during June and early July, to blue crabs (Callinectes sapidus) and other fishes (primarily Atlantic silversides, Menidia menidia and Atlantic menhaden, Brevortia tyrannus) later in the summer. Variations in prey selection appeared to be related to changes in the spatial distribution of predators and spatio-temporal variation in prey availability. In laboratory experiments, summer flounder (271-345 mm total length, TL) preferred demersal winter flounder to a pelagic fish (Atlantic silversides) and a benthic invertebrate (sand shrimp) prey, and the vulnerability of winter flounder increased with increasing prey body size from 20 to 90 mm TL. Experiments testing habitat effects showed that mortality of winter flounder in three different size classes (20-29, 40-49, 60-69 mm TL) was not influenced by sediment grain sizes permitting differential burial of the prey. However, vegetation enhanced survival, with fish suffering lower mortality in eelgrass (Zostera marina, 15+/-0.04%) than in sea lettuce (Ulva lactuca, 38+/-0.04%) or bare sand (70+/-0.07%) when the macrophytes were planted to produce similar leaf surface areas (5000 cm(2) m(-2)). Prey vulnerability appeared to be related to the role of vision in the predator's attack strategy and prey activity levels.     

Testes Investment along a Vertical Depth Gradient in an Herbivorous Fish

Males are expected to adjust testes investment according to the varying level of sperm competition that they experience. Spatial and temporal variation in population density likely influences sperm competition. In herbivorous aquatic organisms, densities often decrease along a vertical depth gradient, because their food is photosynthetic and thus becomes less abundant in deeper regions where less light penetrates. This decrease should be dramatic on a steep slope, which allows testing of the association between density and testes investment at the within‐population level. We tested the effect in the socially monogamous herbivorous cichlid fish Variabilichromis moorii living on a steep slope in Lake Tanganyika. We examined competitor density and food abundance as ecological factors, territory defense behaviors and phenotypic traits (testes investment and somatic investment), and compared them between shallow (4–6 m depth) and deep habitats (10–13 m depth) separated by several dozen meters. We found that food availability drastically decreased with increasing depth and that V . moorii was much more abundant in shallower habitats. Males in shallower habitats were in better physical condition (based on fat and liver mass) despite experiencing greater costs in terms of territory defense. Testes investment differed in areas with different competitor density and food abundance along a vertical depth gradient, but competitor density was the most explanatory factor of the difference. This suggests that this herbivorous fish would change testes investment in response to population density.     

Intense Habitat-Specific Fisheries-Induced Selection at the Molecular Pan I Locus Predicts Imminent Collapse of a Major Cod Fishery

Predation is a powerful agent in the ecology and evolution of predator and prey. Prey may select multiple habitats whereby different genotypes prefer different habitats. If the predator is also habitat-specific the prey may evolve different habitat occupancy. Drastic changes can occur in the relation of the predator to the evolved prey. Fisheries exert powerful predation and can be a potent evolutionary force. Fisheries-induced selection can lead to phenotypic changes that influence the collapse and recovery of the fishery. However, heritability of the phenotypic traits involved and selection intensities are low suggesting that fisheries-induced evolution occurs at moderate rates at decadal time scales. The Pantophysin I (Pan I) locus in Atlantic cod (Gadus morhua), representing an ancient balanced polymorphism predating the split of cod and its sister species, is under an unusual mix of balancing and directional selection including current selective sweeps. Here we show that Pan I alleles are highly correlated with depth with a gradient of 0.44% allele frequency change per meter. AA fish are shallow-water and BB deep-water adapted in accordance with behavioral studies using data storage tags showing habitat selection by Pan I genotype. AB fish are somewhat intermediate although closer to AA. Furthermore, using a sampling design covering space and time we detect intense habitat-specific fisheries-induced selection against the shallow-water adapted fish with an average 8% allele frequency change per year within year class. Genotypic fitness estimates (0.08, 0.27, 1.00 of AA, AB, and BB respectively) predict rapid disappearance of shallow-water adapted fish. Ecological and evolutionary time scales, therefore, are congruent. We hypothesize a potential collapse of the fishery. We find that probabilistic maturation reaction norms for Atlantic cod at Iceland show declining length and age at maturing comparable to changes that preceded the collapse of northern cod at Newfoundland, further supporting the hypothesis. We speculate that immediate establishment of large no-take reserves may help avert collapse.     

Evidence of artisanal fishing impacts and depth refuge in assemblages of Fijian reef fish

Protection from fishing generally results in an increase in the abundance and biomass of species targeted by fisheries within marine reserve boundaries. Natural refuges such as depth may also protect such species, yet few studies in the Indo Pacific have investigated the effects of depth concomitant with marine reserves. We studied the effects of artisanal fishing and depth on reef fish assemblages in the Kubulau District of Vanua Levu Island, Fiji, using baited remote underwater stereo-video systems. Video samples were collected from shallow (5–8 m) and deep (25–30 m) sites inside and outside of a large old marine reserve (60.6 km², 13 years old) and a small new marine reserve (4.25 km², 4 years old). Species richness tended to be greater in the shallow waters of the large old reserve when compared to fished areas. In the deeper waters, species richness appeared to be comparable. The difference in shallow waters was driven by species targeted by fisheries, indicative of a depth refuge effect. In contrast, differences in the abundance composition of the fish assemblage existed between protected and fished areas for deep sites, but not shallow. Fish species targeted by local fisheries were 89% more abundant inside the large old reserve than surrounding fished areas, while non-targeted species were comparable. We observed no difference in the species richness or abundance of species targeted by fisheries inside and outside of the small new reserve. This study suggests that artisanal fishing impacts on the abundance and species richness of coral reef fish assemblages and effects of protection are more apparent with large reserves that have been established for a long period of time. Observed effects of protection also vary with depth, highlighting the importance of explicitly incorporating multiple depth strata in studies of marine reserves.     

Bathymetric Variation in Recruitment and Relative Importance of Pre- and Post-Settlement Processes in Coral Assemblages at Lyudao (Green Island), Taiwan

Studies on coral communities have typically been conducted in shallow waters (∼5 m). However, in the face of climate change, and as shallow coral communities become degraded, a greater understanding of deeper coral communities is needed as they become the main reef remnants, playing a central role in the future of coral reefs. To understand the dynamics of deeper coral assemblages, the recruitment and taxonomic composition of different life-stages at 5 and 15 m depths were compared at three locations in Lyudao, southeastern Taiwan in 2010. Coral recruits (<1 cm diameter, <4 months old) were examined using settlement plates. Juvenile corals (1–5 cm, several years old) were examined with quadrats, and adult corals (>5 cm, several years to decades old) were examined using transect lines. Pocilloporid and poritid corals had similar and higher numbers of recruits at 5 m compared to 15 m, whereas acroporid recruits were more abundant at 15 m. The primary cause for the former may be larval behavior, such that they position themselves in shallow waters, while that for the latter may be the dominance of brooding acroporid species (Isopora spp.) at 15 m. The taxonomic composition, especially between recruits and juveniles/adults, was more similar at 15 m than at 5 m. These results suggest a change in the relative importance of pre- and post-settlement processes in assemblage determinants with depth; coral assemblages in shallow habitats (more disturbed) are more influenced by post-settlement processes (mortality events), while those in deeper habitats (more protected) are more influenced by pre-settlement processes (larval supply).     

The influence of anthropogenic shoreline changes on the littoral abundance of fish species in German lowland lakes varying in depth as determined by boosted regression trees

Residential development on lake shores is regularly associated with the conversion of natural littoral habitats to riprap, sheet piles, beaches, parks, or marinas. The subsequent loss of littoral vegetation induces a decline of structural diversity and impacts littoral fish communities. These impacts may be shaped by lake morphology. Using boosted regression trees (BRT) to relate fish abundance data from 57 north-east German lowland lakes to various factors characterizing trophic state, lake morphology, and shoreline development, we investigated the response of 11 fish species to shoreline development. The analyses revealed that mean depth followed by trophic level and shoreline length (SL) contributed most in explaining littoral fish abundance. BRT models built for deep and shallow lakes separately confirmed that primarily trophic level and SL influenced fish abundance but that littoral vegetation was relatively more important in deep compared to shallow lakes, indicating that the effects of shoreline development may be more pronounced in deep lakes where the littoral makes up a smaller proportion of the lake area as compared to shallow lakes. The BRT further demonstrated species-specific responses to shoreline degradation, indicating that the reliability of ecological quality assessments of lakes can be improved by applying separate metrics for individual species.