Feeding preference of the sea urchin Lytechinus variegatus (Lamarck, 1816) on seaweeds

Abstract

A B S T R A C TSeaweeds exhibit different strategies to minimize the damage caused by herbivores and also to influence the feeding preference of these consumers. This study evaluated the feeding preference of the sea urchin Lytechinus variegatus through multiple-choice experiments using the seaweeds Caulerpa racemosa, Dictyota menstrualis, Osmundaria obtusiloba, Plocamium brasiliense, Sargassum sp., and Ulva sp. In order to verify the importance of morphological and chemical aspects on this feeding preference, two assay-types were carried out using live and powdered macroalgae, respectively. Two different methods were employed to analyze the results obtained: comparison between biomass losses versus autogenic changes, and inclusion of autogenic values in biomass loss through herbivory. In both experiments a clear differential consumption of certain species of seaweeds by L. variegatus was observed, in the following decreasing order of preference: R E S U M OAs macroalgas apresentam diversos tipos de estratégias para minimizar os danos gerados por herbívoros que influenciam a preferência alimentar dos consumidores. Este estudo avaliou a preferência alimentar do ouriço-do-mar Lytechinus variegatus em experimentos de múltipla escolha utilizando as macroalgas bentônicas Caulerpa racemosa, Dictyota menstrualis, Osmundaria obtusiloba, Plocamium brasiliense, Sargassum sp., e Ulva sp. Para verificar a importância dos aspectos morfológicos e químicos na preferência, os ensaios foram realizados com algas vivas e em pó, respectivamente. Foram utilizados dois métodos distintos de análise de dados: comparação entre a perda de biomassa e as mudanças por autogenia, e a incorporação dos valores de autogenia à perda de biomassa por herbivoria. Em ambos os experimentos observou-se uma clara preferência de L. variegatus por certas espécies de macroalgas em relação a outras, em ordem decrescente de preferência: C. racemosa ≈ Ulva sp. > O. obtusiloba ≈ Sargassum sp. > P. brasiliense > D. menstrualis. Além disso, constatou-se que os dois métodos de análise produziram resultados muito similares. De acordo com os resultados, a preferência alimentar de L. variegatus é provavelmente condicionada pela química defensiva produzida por P. brasiliense e D. menstrualis e aspectos morfológicos presentes em C. racemosa, Ulva sp., O. obtusiloba e Sargassum sp.

Idiosyncratic responses of seagrass phenolic production following sea urchin grazing

“…Because the results of the feeding trials failed to detect evidence of an urchin preference, it appears that this urchin is unaffected by seagrass chemical composition. This contrasts with our expectations based on other urchin feeding preference studies, including some with Lytechinus variegatus, showing that macroalgal and seagrass chemistry, along with structural defenses, can strongly affect urchin feeding preferences (McConnell et al 1982, Verges et al 2007b, Souza et al 2008.…”

Chemical defense in the red seaweed Plocamium brasiliense: spatial variability and differential action on herbivores

“…These results also confirm previous evidence that Brazilian P. brasiliense was one of the last food items preferred by L. variegatus probably due to defensive chemicals produced by this macroalga (Souza et al, 2008). In general, chemicals from Plocamium species are very little explored in the context of its ecological roles, but it is known that crude extract of P. cartilagineum was significantly rejected by fish, sea star and amphipod et al, 2004), and benthic organisms living in close proximity to P. hamatum, including corals and sponges, exhibited several degrees of necrosis due to chemicals of this macroalga (De Nys et al, 1991).…”

Agar-based Biocomposites slow down Progression in the Reproductive Cycle Facilitating Synchronization of the Gonads of Reared Specimens of Paracentrotus lividus

“…In addition to nutrient composition, palatability is also a key concern in the formulation of artificial feed, as it stimulates eating activity and therefore the ingestion rate [40]. Sea urchins have clear feeding preferences both in the field and in confined conditions [14,41,42]. In our experiments Paracentrotus lividus specimens actively grazed on some biocomposites (Agar and Agar-low esterification apple pectin) but were not attracted by others (for example alginic acid and gellan-based biocomposites).…”