Browsing by Author "Gartenstein, Simon"

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    Limited effects of management and ecological subsidies on the size-spectra of kelp forest fish communities
    (2024) Gartenstein, Simon; Perez-Matus, Alejandro; Heather, Freddie J.; Godoy, Natalio; Torres-Canete, Felipe; Catalan, Alexis M.; Valdivia, Nelson
    Animal body size influences key ecological processes across biological hierarchies. For instance, densities (N) and community biomass (B) are allometric functions of body mass (M). Energetic equivalence predicts that density scales with body size as N proportional to M-0.75 and that biomass scales with body size as B proportional to M0.25. However, the way fish size-spectra are influenced by external processes, such as ecological subsidies (e.g. nutrients from upwelling zones) and fisheries management, is not well understood. We investigated the relationship of body size with density and biomass of reef fishes associated with subtidal kelp forests of Lessonia trabeculata that were influenced by the separate and interactive effects of management (Territorial Use Rights for Fisheries [TURF] or open access) and upwelling regimes (upwelling or non-upwelling zones). Fish densities and lengths were recorded using underwater visual censuses. Within each of 4 locations, paired TURF and open-access sites were surveyed. We surveyed 18 fish species, encompassing 1511 individuals ranging between 2 and 6639 g. We observed that fish size-spectra deviated from energetic equivalence, as N proportional to M-0.32 and B proportional to M2.2, indicating that the contribution of large-sized fishes to community density and biomass was greater than that predicted by energetic equivalence. Multi-model inference suggested that TURF and upwelling scenarios had weak effects on fish size-spectra. Results indicated that fish communities may have access to external food sources beyond local kelp forests. In addition, size-spectra may be a spatially persistent attribute of these fish communities.
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    Stability of rocky intertidal communities, in response to species removal, varies across spatial scales
    (2021) Valdivia, Nelson; Lopez, Daniela N.; Fica-Rojas, Eliseo; Catalan, Alexis M.; Aguilera, Moises A.; Araya, Marjorie; Betancourtt, Claudia; Burgos-Andrade, Katherine; Carvajal-Baldeon, Thais; Escares, Valentina; Gartenstein, Simon; Grossmann, Mariana; Gutierrez, Barbara; Kotta, Jonne; Morales-Torres, Diego F.; Riedemann-Saldivia, Barbara; Rodriguez, Sara M.; Velasco-Charpentier, Catalina; Villalobos, Vicente, I; Broitman, Bernardo R.
    Improving our understanding of stability across spatial scales is crucial in the current scenario of biodiversity loss. Still, most empirical studies of stability target small scales. We experimentally removed the local space-dominant species (macroalgae, barnacles, or mussels) at eight sites spanning more than 1000 km of coastline in north- and south-central Chile, and quantified the relationship between area (the number of aggregated sites) and stability in aggregate community variables (total cover) and taxonomic composition. Resistance, recovery, and invariability increased nonlinearly with area in both functional and compositional domains. Yet, the functioning of larger areas achieved a better, albeit still incomplete, recovery than composition. Compared with controls, smaller disturbed areas tended to overcompensate in terms of total cover. These effects were related to enhanced available space for recruitment (resulting from the removal of the dominant species), and to increasing beta diversity and decaying community-level spatial synchrony (resulting from increasing area). This study provides experimental evidence for the pivotal role of spatial scale in the ability of ecosystems to resist and recover from chronic disturbances. This knowledge can inform further ecosystem restoration and conservation policies.
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    The natural diet of Prolatilus jugularis inhabiting Lessonia trabeculata kelp forests of south-central Chile
    (2024) Gartenstein, Simon; Fica-Rojas, Eliseo; Perez-Matus, Alejandro; Godoy, Natalio; Torres-Canete, Felipe; Valdivia, Nelson
    Kelp forests support species-rich food webs that predator-prey interactions may sustain. Here, we analyze prey availability and stomach contents of the predatory fish Prolatilus jugularis in an unexplored subtidal kelp forest of Lessonia trabeculata in south-central Chile. In the kelp forest, 42 invertebrate taxa and 1016 individuals were observed. In the diet of P. jugularis, 21 taxa and 130 individuals were identified. Crustacea, particularly amphipods, were the dominant and more frequent taxa in the kelp forest and stomach contents. Annelida and Mollusca were also present in the kelp forest and diets but were less abundant. We did not find a statistically significant correlation between kelp forest and stomach-content prey abundances and frequencies. Also, dominance structure significantly differed between kelps and stomach contents. Our results indicate that P. jugularis could feed in other habitats outside the survey area. Seven predatory fish were sampled in the kelp forest. Pinguipes chilensis was the dominant fish, with 65% of the total fish biomass, followed by P. jugularis with 20%.