Population dynamics and reproductive biology of the sandhopper Atlantorchestoidea brasiliensis (Amphipoda: Talitridae) of a sandy beach in Southwestern Atlantic Coast

Abstract

ABSTRACT Biodiversity losses can alter ecosystem functioning. In this context, sandy beach macrobenthic species are highly vulnerable due to anthropogenic impacts and global changes. Evaluating and monitoring life history-based biological traits is a key goal for ecologists to investigate biodiversity and ecosystem functioning changes. Due to environmental conditions, however, life-history traits may vary among regions, even for similar taxa. The South Atlantic Coast is highly under-sampled compared with North Atlantic regions. Here, we investigate the life cycle, population dynamics, and reproductive biology of the key species Atlantorchestoidea brasiliensis (Dana, 1853) from a Southwestern Atlantic Coast sandy beach. We followed field time-series data of multiple life-cycle-based biological traits. The body length of A. brasiliensis varied from 1.25 to 11.86 mm. Longevity was estimated at 11.9 months for both males and females. Growth parameters were estimated as L∞ = 12.9 mm, k = 2.3, t0 = −0.10 for males and L∞ = 12.3, k = 2, t0 = −0.13 for females. The population showed continuous reproduction and multiple cohorts without seasonality. The mean sex ratio was female-biased (1.71: 1). Females bear a mean of 4–6 eggs per marsupium, with egg volume between 0.0472 and 0.0501 mm3. Female maturation was estimated at age 3.53 months, with L50% = 7.0 mm. Biological trait evaluations of A. brasiliensis were similar to those found for amphipods in South America and differed from those of similar taxa found in North Atlantic. Monitoring life history based-biological traits is essential to make management decisions, especially in environmental protection areas with vulnerable species whose recovery is challenging, to maintain the biodiversity and ecosystem functioning.