A modeling approach for reposition dynamics of litter composition in coastal areas of the city of Santos, Sao Paulo, Brazil.

Given the complexity of the dynamics in litter reposition, our objective was modeling the possible main and interaction effects of tidal oscillations, seasons of the year and the moon phases over the solid waste in Santos beaches. A total of 80 collections were carried out using quadrat sampling, from which we classified, counted and weighed all residue items. We fitted mixed Hurdle models to the output datasets and performed hypotheses tests based on this framework. We found plastic to be the most abundant residue in all seasons, moon phases and tides, followed by Styrofoam and wood. Our models suggest the strongest effect was due to seasonal variations, which, in turn, may be related to different human activities. Although the dynamics of different components showed independency of all interaction structures, plastics depended on the interaction of tide and season, whose impact over estuarine life and ecosystem services shall be further investigated.

Seasonal, Lunar and Tidal Influences on Habitat Use of Indo-Pacific Humpback Dolphins in Beibu Gulf, China.

Shanshan Li, Huili Gao, Xiuqing Hao, Lin Zhu, Ting Li, Hongke Zhang, Yi Zhou, Xinrong Xu, Guang Yang, and Bingyao Chen (2018) Cetacean habitat use based on different environmental phases varies between species and geographies, and little is known about Pacific humpback dolphin habitat use in the Beibu Gulf. Here we aimed to identify seasonal, lunar and tidal influences on the spatial use of Beibu humpback dolphins based on two parameters: water depth and distance to an estuary. The ANOVA test indicated that habitat use was influenced by seasons and tidal phases, but not lunar phases. The humpback dolphins utilized shallow areas near an estuary throughout the wet season and high tides, and moved toward deeper water during the dry season and low tides. This habitat preference is likely synchronized with prey seasonal and tidal movements. The wet season and high tides bring abundant prey resources and increase accessibility to inshore shallow waters for humpback dolphins. The present study provides new information on regular habitat use by Indo- Pacific humpback dolphins, which is crucial for developing effective conservation strategies.

Model-based analysis of causes for habitat segregation in Idotea species (Crustacea, Isopoda).

On the shore of the rocky island of Helgoland (North Sea) two closely related isopod species, Idotea balthicaPallas, 1772, and Idotea granulosaRathke, 1843, share a similar fundamental niche but inhabit well-separated habitats. Idotea balthica inhabits floating algae at the sea surface and accumulations of decaying algae on the seafloor, whereas I. granulosa primarily occurs in intertidal macroalgal belts. In laboratory experiments on individually reared isopods I. balthica outperformed I. granulosa with regard to growth, reproduction, and mortality in both a fully inundated habitat and in a tidal habitat with 5 h of daily emergence. We hypothesized that habitat segregation in the two isopod species is driven by one or multiple types of biotic interactions: (1) no interaction, (2) cannibalism, (3) intraguild predation, and (4) terrestrial predation. In order to evaluate how habitat segregation can be explained by each of these interaction types we employed a size-structured population model to account for the body-size-dependent predation. Net population growth rates were fitted to the simulations as a measure of population fitness. Experimental results served as database for parameter and process identification. As predation rates were unknown, we performed a sensitivity analysis for these. We found that below 5 h of daily tidal emergence either cannibalism or terrestrial predation sufficed to explain habitat segregation. Intraguild predation, in contrast, advantaged I. balthica in any case. From linear extrapolation of the effects occurring under conditions of 5 h of daily tidal emergence, we predict that contrasting physiological responses in I. balthica and I. granulosa would cause segregation even without any interaction if emergence lasted long enough.